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  • phosphorus  (206)
  • Animals
  • Chemical Engineering
  • Rat
  • Springer  (258)
  • 1990-1994  (258)
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  • 1
    Electronic Resource
    Electronic Resource
    Historical changes in sediments of Pyramid Lake, Nevada, USA: consequences of changes in the water balance of a terminal desert lake (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 87-101 
    Details
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678089
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  • 2
    Electronic Resource
    Electronic Resource
    Environmental impact of fertilizing soils by using sewage and animal wastes (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 1-22 
    Details
    ISSN: 1573-0867
    Keywords: animal slurries and manures ; applications to soils ; carbon- ; nitrogen- ; phosphorus ; contamination ; crop production ; dissemination ; hazardous organics ; heavy metals ; inputs ; macro- and micronutrients ; pathogens ; sewage sludges ; survival- ; transfer- ; transport and adsorption rates in soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The European Community is producing annually about 300 × 106 tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM−1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg−1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg−1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha−1 a−1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes. Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750669
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  • 3
    Electronic Resource
    Electronic Resource
    Land application of poultry litter and water quality in Oklahoma, U.S.A. (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    Details
    ISSN: 1573-0867
    Keywords: Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750462
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  • 4
    Electronic Resource
    Electronic Resource
    Response of ensete (Ensete ventricosum W.) to mineral fertilizers in southwest Ethiopia (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
    Details
    ISSN: 1573-0867
    Keywords: Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00748551
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of phosphate on the sorption, desorption and plant-availability of selenium in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 189-197 
    Details
    ISSN: 1573-0867
    Keywords: interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750246
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  • 6
    Electronic Resource
    Electronic Resource
    Renal eicosanoids and blood pressure in genetically hypertensive rats of the lyon strain (1994)
    Springer
    Journal of biomedical science 1 (1994), S. 201-203 
    Details
    ISSN: 1423-0127
    Keywords: Hypertension ; Eicosanoid ; Rat ; Genetics ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present paper reviews the evidence for a possible involvement of renal eicosanoids in the pathophysiology of high blood pressure in genetically hypertensive rats of the Lyon strain. Both in vivo and in vitro experiments suggest that an increased ability to synthesize the vasoconstrictor prostaglandin H2 and/or thromboxane A2 in renal vessels (1) acts as an autocrine amplifier of pressor agents and (2) may contribute to resetting the pressure natriuresis curve which is a prerequisite for the development and maintenance of hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253302
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  • 7
    Electronic Resource
    Electronic Resource
    Phosphorus and nitrogen limitation of algal biomass across trophic gradients (1994)
    Springer
    Aquatic sciences 56 (1994), S. 16-28 
    Details
    ISSN: 1420-9055
    Keywords: Chlorophyll-a ; phosphorus ; nitrogen ; lake ecosystem ; nutrient limitation ; regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regression results based on data from 46 northern temperate lakes show that total phosphorus (TP) is the best predictor for phytoplankton (as chl-a) at lower trophic levels, TP 〈 200 mg · m−3. A regression including both TP and TN as regressors is the best predictor for lakes with TP 〉 200 mg · m−3. However, the good correlation is probably due to a high correlation between lake average chl-a (all years observed) and lake average TP and TN. Within single hypereutrophic lakes, TN alone is the best predictor. It was not possible to identify a medium trophic domain where TN and TP in combination was the best predictor for chl-a. The ratio TN:TP in the water decreases from about 40 to about 5 with increasing trophic level. Optimum TN:TP ratio for algal species with high abundance during late summer and autumn reflects this decreasing ratio, but within a lesser range, i.e., 20 to 5. In contrast, TN:TP ratios for species abundant during the early vernal period showed no, or an inverse, relation to the TN:TP ratio of the water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877432
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  • 8
    Electronic Resource
    Electronic Resource
    Contribution of nitrogen and phosphorus by precipitation in the drainage basin of the Santillana Reservoir (Madrid) (1994)
    Springer
    Environmental geology 23 (1994), S. 99-104 
    Details
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00766982
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  • 9
    Electronic Resource
    Electronic Resource
    Noninvasive loading of the rat ulna in vivo induces a strain-related modeling response uncomplicated by trauma or periostal pressure (1994)
    Springer
    Calcified tissue international 54 (1994), S. 241-247 
    Details
    ISSN: 1432-0827
    Keywords: Loading ; Strain ; Modeling ; Rat ; Ulna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Adaptive changes in bone modeling in response to noninvasive, cyclic axial loading of the rat ulna were compared with those using 4-point bending of the tibia. Twenty cycles daily of 4-point bending for 10 days were applied to rat tibiae through loading points 23 and 11 mm apart. Control bones received nonbending loads through loading points 11 mm apart. As woven bone was produced in both situations, any strain-related response was confounded by the response to direct periosteal pressure. Four-point bending is not, therefore, an ideal mode of loading for the investigation of strain-related adaptive modeling. The ulna's adaptive response to daily axial loading over 9 days was investigated in 30 rats. Groups 1–3 were loaded for 1200 cycles: Group 1 at 10 Hz and 20 N, Group 2 at 10 Hz and 15 N, and Group 3 at 20 Hz and 15 N. Groups 4 and 5 received 12,000 cycles of 20 N and 15 N at 10 Hz. Groups 1 and 4 showed a similar amount of new bone formation. Group 4 showed the same pattern of response but in reduced amount. The responses in Groups 2 and 3 were either small or absent. Strains were measured with single-element, miniature strain gauges bonded around the circumference of dissected bones. The 20 N loading induced peak strains of 3500–4500 μstrain. The width of the periosteal new bone response was proportional to the longitudinal strain at each point around the bone's circumference. It appears that when a bone is loaded in a normal strain distribution, an osteogenic response occurs when peak physiological strains are exceeded. In this situation the amount of new bone formed at each location is proportional to the local surface strain. Cycle numbers between 1200 and 12,000, and cycle frequencies between 10 and 20 Hz have no effect on the bone's adaptive response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301686
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of running exercise on the bone loss induced by orchidectomy in the rat (1994)
    Springer
    Calcified tissue international 55 (1994), S. 33-37 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Rat ; Orchidectomy ; Exercise ; Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effect of exercise on castration-induced osteoporosis in 3-month-old male rats weighing 264±4 g at the beginning of the experiment was studied. A testosterone deficiency was induced by orchidectomy (ORC), and the exercise group ran 10 m/minute for 1 hour a day on a treadmill at 0% grade. There were seven groups of eight rats (n=56) randomized into a control group killed at time 0, and sham, ORC and ORC and exercise groups killed at 4 and 8 weeks. ORC reduced body weight gain (with analysis of variance (ANOVA) P〈0.001), and at 4 weeks the body weight was 343±14 g in ORC group and 301±4 g in the ORC and exercise group (P〈0.01). The increase in femoral length was slower in the ORC+exercise groups. The ash weight of the tibia did not decrease significantly after ORC or ORC+ exercise. ORC did not affect 45Ca incorporation, but exercise slightly increased it in the whole tibia 8 weeks after ORC (with ANOVA P=0.057). ORC had significantly lowered the trabecular bone volume in the secondary spongiosa of the distal femur at 4 and 8 weeks, and exercise did not prevent this. This is an opposite finding to our previous study with ovariectomized female rats [12]. ORC also significantly had reduced the osteoblast-lined trabecular bone surface and the number of osteoclasts by 8 weeks after the operation. Exercise increased the osteoblast-lined surface and the number of osteoclasts. The mechanical strength of the femoral neck also was reduced after ORC and this was not prevented by exercise either. In conclusion, ORC reduces bone growth and turnover which leads to osteopenia in growing rats. Moderate treadmill exercise does not reverse the ORC-induced loss of trabecular bone and the reduced mechanical strength of the femoral neck, although it has a positive effect on the osteoblast and osteoclast indices and on calcium incorporation into bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310166
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  • 11
    Electronic Resource
    Electronic Resource
    The in vivo effect of a new, in vitro, extremely potent vitamin D3 analog KH1060 on the suppression of renal allograft rejection in the rat (1994)
    Springer
    Calcified tissue international 54 (1994), S. 150-154 
    Details
    ISSN: 1432-0827
    Keywords: Vitamin D analog ; KH1060 ; Kidney transplantation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract KH1060 is a new 20-epi-vitamin D3 analog, which has exerted a considerable immunosuppressive potency in vitro. We have tested in vivo the effect of KH1060 on the suppression of renal allograft rejection in the rat. Allogenic kidney transplantation from DA donor rats to Lewis recipient rats treated intraperitoneally with KH1060 in doses from 0.2 to 6 μg/kg/day, or saline (placebo group), or CyA 10 mg/kg/day for 10 days (positive control group), was performed. Median graft survival time in KH1060-treated groups was 7–9 days, in the placebo group 6 days, whereas CyA led to long-term graft survival, 34 days in 50% of rats and 〉100 days in 50% of rats. In vivo, KH1060 failed to prolong renal allograft survival considerably, and led to development of hypercalcemia. Our results stress the existence of a large discrepancy between the in vitro and in vivo immunoregulatory effects of this vitamin D analog.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296066
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  • 12
    Electronic Resource
    Electronic Resource
    Effect of 1α-vitamin D3 on bone strength and composition in growing rats with and without corticosteroid treatment (1994)
    Springer
    Calcified tissue international 55 (1994), S. 443-450 
    Details
    ISSN: 1432-0827
    Keywords: Bone mechanics ; Bone composition ; Vitamin D3 ; Corticosteroid ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of 1α-vitamin D3 were studied for 6 months in 2-month-old male and female rats on a moderately low calcium diet with or without low-dose prednisolone treatment. Both cortical bone mechanical and biochemical properties were examined. Femoral bone specimens were subjected to torsional loading tests. With age, bone strength and stiffness increased in both sexes, accompanied by an increased degree of mineralization (bone ash and calcium concentrations). During growth, strength and stiffness increased more in male than in female rats. When 1α-vitamin D3 (0.5 μg/kg/day) was given alone, bone mechanical competence improved significantly whereas insulin-like growth factor-I (IGF-I) and calcium concentrations in the bone matrix were significantly reduced. Treatment with low-dose prednisolone (0.5 mg/kg/day) alone did not influence bone mechanical properties compared with intact control rats (without prednisolone) although a significant reduction in calcium concentration and an increased phosphorus concentration were measured. A combined therapy with prednisolone and 1α-vitamin D3 significantly increased bone strength, toughness, and stiffness compared with control bones. Both mineralization degree (ash and calcium concentration) and IGF-I concentration were decreased. We conclude that (1) mechanical properties of rat cortical bones improve relatively more in males compared with agematched females during growth which is related to increased bone mass and size, (2) low-dose prednisolone treatment does not change mechanical properties in males, and altered them only nonsignificantly in females despite a change in mineralization degree in both sexes; (3) treatment with 1α-vitamin D3 results in a consistent increase in mechanical competence of the bone accompanied by a significant decrease in IGF-I concentration in the bone matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298558
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  • 13
    Electronic Resource
    Electronic Resource
    Expression of the α-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig (1994)
    Springer
    Cell & tissue research 278 (1994), S. 617-624 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light- and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrophs. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050253
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  • 14
    Electronic Resource
    Electronic Resource
    Expression of the α-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig (1994)
    Springer
    Cell & tissue research 278 (1994), S. 617-624 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light-and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrops. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331382
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  • 15
    Electronic Resource
    Electronic Resource
    The immunolocalization of small nuclear ribonucleoprotein particles in testicular cells during the cycle of the seminiferous epithelium of the adult rat (1994)
    Springer
    Cell & tissue research 278 (1994), S. 363-378 
    Details
    ISSN: 1432-0878
    Keywords: Key words: snRNPs ; Testis ; Spermatocytes ; Spermatids ; Immunocytochemistry ; Chromatoid body ; Intermitochondrial nuage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The objective of this study was to determine the cellular and subcellular distribution of small nuclear ribonucleoprotein particles (snRNPs) in the adult rat testis in relation to the different cell types at the various stages of the cycle of the seminiferous epithelium. The distribution of snRNPs in the nucleus and cytoplasm of germ cells was quantitated in an attempt to correlate RNA processing with morphological and functional changes occurring during the development of these cells. Light-microscopic immunoperoxidase staining of rat testes with polyclonal anti-Sm and monoclonal anti-Y12 antibodies localized spliceosome snRNPs in the nuclei and cytoplasm of germ cells up to step 10 spermatids. Nuclear staining was intense in Sertoli cells, spermatogonia, spermatocytes, and in the early steps of round spermatid development. Although comparatively weaker, cytoplasmic staining for snRNPs was strongest in mid and late pachytene spermatocytes and early round spermatids. Quantitative electron-microscopic immunogold labeling of Lowicryl embedded testicular sections confirmed the light-microscopic observations but additionally showed that the snRNP content peaked in the cytoplasm of mid-pachytene spermatocytes and in the nuclei of late pachytene spermatocytes. The immunogold label tended to aggregate into distinct loci over the nuclear chromatin. The chromatoid body of spermatids and spermatocytes and the finely granular material in the interstices of mitochondrial aggregates of spermatocytes were found to be additional sites of snRNP localization and were intensely labeled. This colocalization suggests that these dense cytoplasmic structures may be functionally related. Anti-U1 snRNP antibodies applied to frozen sections showed the same LM localization pattern as spliceosome snRNPs. Anti-U3 snRNP antibodies applied to frozen sections stained nucleoli of germ cells where pre-rRNA is spliced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414179
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  • 16
    Electronic Resource
    Electronic Resource
    Selective association of nerve fibres immunoreactive for substance P or bombesin with putative cholinergic neurons of the male rat major pelvic ganglion (1994)
    Springer
    Cell & tissue research 278 (1994), S. 589-594 
    Details
    ISSN: 1432-0878
    Keywords: Autonomic ganglia ; Neuropeptides ; Pelvic plexus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The male rat major pelvic ganglion contains both sympathetic and parasympathetic neurons that supply the lower urinary and digestive tracts, and the reproductive organs. The aim of this study was to describe the distribution and identify potential targets of sensory and intestinofugal axons in this ganglion. Two putative markers of these projections were chosen, substance P for primary sensory axons and bombesin for myenteric intestinofugal projections. Varicose substance P-immunoreactive axons were associated only with non-noradrenergic (putative cholinergic) somata, and most commonly with those that contained vasoactive intestinal peptide. Immunoreactivity for substance P was also present in a small group of non-noradrenergic somata, many of which were immunoreactive for enkephalins, neuropeptide Y or vasoactive intestinal peptide. Bombesin immunoreactivity was found only in preterminal and terminal (varicose) axons, the latter of which were exclusively associated with non-noradrenergic somata that contain neuropeptide Y-immunoreactivity. Some varicose axons containing either substance P-or bombesin-immunoreactivity were intermingled with clumps of small, intensely fluorescent cells. These studies indicate that substance P-and bombesin-immunoreactive axons are likely to connect with numerically small, but discrete, populations of pelvic neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331378
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  • 17
    Electronic Resource
    Electronic Resource
    Zona glomerulosa of the adrenal gland in a transgenic strain of rat: a morphologic and functional study (1994)
    Springer
    Cell & tissue research 278 (1994), S. 21-28 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Adrenal cortex ; Renin-angiotensin system ; Steroidogenesis ; Electron microscopy ; Morphometry ; Rat ; transgenic (mRen2) 27
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Transgenic rats for the murine Ren-2 gene display high blood pressure, low circulating levels of angiotensin II, and high renin content in the adrenal glands. Moreover, transgenic rats possess an increased aldosterone secretion (maximal from 6 to 18 weeks of age), paralleling the development of hypertension. To investigate further the cytophysiology of the adrenal glands of this strain of rats, we performed a combined morphometric and functional study of the zona glomerulosa of 10-week-old female transgenic rats. Morphometry did not reveal notable differences between zona glomerulosa cells of transgenic and age- and sex-matched Sprague-Dawley rats, with the exception of a marked accumulation of lipid droplets, in which cholesterol and cholesterol esters are stored. The volume of the lipid-droplet compartment underwent a significant decrease when transgenic rats were previously injected with angiotensin II or ACTH. Dispersed zona glomerulosa cells of transgenic rats showed a significantly higher basal aldosterone secretion, but their response to angiotensin II and ACTH was similar to that of Sprague-Dawley animals. Angiotensin II-receptor number and affinity were not dissimilar in zona glomerulosa cells of transgenic and Sprague-Dawley rats. These data suggest that the sustained stimulation of the adrenal renin-angiotensin system in transgenic animals causes an increase in the accumulation in zona glomerulosa cells of cholesterol available for steroidogenesis, as indicated by the expanded volume of the lipid-droplet compartment and the elevated basal steroidogenesis. However, the basal hyperfunction of the zona glomerulosa in transgenic animals does not appear to be coupled with an enhanced responsivity to its main secretagogues, at least in terms of aldosterone secretion.
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    URL: http://dx.doi.org/10.1007/BF00305774
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    The immunolocalization of small nuclear ribonucleoprotein particles in testicular cells during the cycle of the seminiferous epithelium of the adult rat (1994)
    Springer
    Cell & tissue research 278 (1994), S. 363-378 
    Details
    ISSN: 1432-0878
    Keywords: snRNPs ; Testis ; Spermatocytes ; Spermatids ; Immunocytochemistry ; Chromatoid body ; Intermitochondrial nuage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The objective of this study was to determine the cellular and subcellular distribution of small nuclear ribonucleoprotein particles (snRNPs) in the adult rat testis in relation to the different cell types at the various stages of the cycle of the seminiferous epithelium. The distribution of snRNPs in the nucleus and cytoplasm of germ cells was quantitated in an attempt to correlate RNA processing with morphological and functional changes occurring during the development of these cells. Light-microscopic immunoperoxidase staining of rat testes with polyclonal anti-Sm and monoclonal anti-Y12 antibodies localized spliceosome snRNPs in the nuclei and cytoplasm of germ cells up to step 10 spermatids. Nuclear staining was intense in Sertoli cells, spermatogonia, spermatocytes, and in the early steps of round spermatid development. Although comparatively weaker, cytoplasmic staining for snRNPs was strongest in mid and late pachytene spermatocytes and early round spermatids. Quantitative electron-microscopic immunogold labeling of Lowicryl embedded testicular sections confirmed the light-microscopic observations but additionally showed that the snRNP content peaked in the cytoplasm of midpachytene spermatocytes and in the nuclei of late pachytene spermatocytes. The immunogold label tended to aggregate into distinct loci over the nuclear chromatin. The chromatoid body of spermatids and spermatocytes and the finely granular material in the interstices of mitochondrial aggregates of spermatocytes were found to be additional sites of snRNP localization and were intensely labeled. This colocalization suggests that these dense cytoplasmic structures may be functionally related. Anti-U1 snRNP antibodies applied to frozen sections showed the same LM localization pattern as spliceosome snRNPs. Anti-U3 snRNP antibodies applied to frozen sections stained nucleoli of germ cells where pre-rRNA is spliced.
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    URL: http://dx.doi.org/10.1007/BF00414179
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    The role of suspended matter in the distribution of dissolved inorganic phosphate, iron and aluminium in the Ems estuary (1994)
    Springer
    Aquatic ecology 28 (1994), S. 383-395 
    Details
    ISSN: 1573-5125
    Keywords: Ems estuary ; phosphorus ; iron ; fluorescence ; aluminium ; adsorption ; suspended matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In winter 1992/1993, a persistent local maximum in fluorescence, dissolved iron, dissolved aluminium and dissolved inorganic phosphate was found, upstream of the turbidity maximum in the freshwater zone of the Ems estuary (The Netherlands — Federal Republic Germany; western Europe). Upstream of this local maximum values ranged from 6 to 9 rel. units fluorescence, 0.9 to 2.4 μmol dm−3 iron, 0.5 to 0.7 μmol dm−3 aluminium and 0.6 to 2.3 μmol dm−3 dissolved inorganic phosphate. Within the maximum peak values of 24 rel. units fluorescence, 5.8 μmol dm−3 iron, 1.4 μmol dm−3 aluminium and 8.3 μmol dm−3 dissolved inorganic phosphate were observed. Downstream, fluorescence (indicator of dissolved organic carbon) showed conservative mixing with sea water, whereas dissolved iron, aluminium and dissolved inorganic phosphate did not. Dissolved aluminium and iron were quickly removed from solution to reach values of ∼100 nmol dm−3 aluminium and ∼0.3 μmol·dm−3 Fe at salinities of approximately 7 PSU. Further seaward iron concentrations gradually decreased to levels below 0.04 μmol dm−3. Dissolved aluminium first decreased to ∼20 nmol dm−3 at 29 PSU and increased again to concentrations of 30–44 nmol dm−3 at higher salinities. Dissolved inorganic phosphate, however, first decreased to upstream concentrations before reaching a secondary peak in the mid-estuarine reaches. At salinities 〉25 PSU dissolved inorganic phosphate mixed conservatively with sea water. It is hypothesized that adsorption-desorption equilibria are responsible for the local maximum values of fluorescence (DOC), iron, aluminium and dissolved inorganic phosphate. The similarity between the observed curves suggests a common underlying process, possibly related to the adjustment of new equilibria between suspended matter of marine and riverine origin.
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    URL: http://dx.doi.org/10.1007/BF02334208
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    Determination of orthophosphate in highly saline waters (1994)
    Springer
    International journal of salt lake research 3 (1994), S. 159-173 
    Details
    ISSN: 1573-8590
    Keywords: phosphorus ; orthophosphate ; phosphomolybdenum blue ; salt effect ; hypersaline ; saline ; lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Standard methods for the determination of phosphorus as phosphate ion are now well established for fresh and marine waters. In highly saline waters, however, salt effects due to ionic strength, or to particular ions present, may result in method interferences. Three methods of analysis of phosphate based on the formation of phosphomolybdenum blue complexes have been evaluated here for hypersaline waters. Stannous chloride reduction in aqueous media exhibits a substantial salt effect and its use is not recommended. Stannous chloride reduction following extraction into non aqueous solvents shows a significant salt effect (up to 30 per cent) in solutions of salinity 〉100 g L−1. Dilution of hypersaline waters to below this salinity may overcome the salt effect but the method suffers from other disadvantages involving resource constraints and health and safety considerations. Ascorbic acid reduction, catalysed by antimony (III) ions, appears to offer the most promise for hypersaline waters. Turbidity in samples having high salinity (〉 100 g L−1) and high phosphorus concentrations (〉 500 μg P L−1) changes the spectral characteristics of solutions but linear calibration curves still result for concentrations in the range 400 to 1,000 μg P L−1. The occurrence of turbidity is also affected by the ionic composition of hypersaline waters since solutions made from sea salt give different results to those made from sodium chloride. Dilution of samples, to give salinities less than 100 g L−1 prior to reduction is recommended to avoid turbidity. The salt effect in these lower salinity waters is less than 3 per cent up to 100 g L−1.
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    URL: http://dx.doi.org/10.1007/BF01990492
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    Growth and elemental content of several sagebrush-steppe species in unburned and post-wildfire soil and plant effects on soil attributes (1994)
    Springer
    Plant and soil 164 (1994), S. 35-41 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphorus ; revegetation ; silica ; succession ; shrubland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fire is the principal means of stand renewal in big sagebrush-steppe communities of western North America. Plant growth following fire may be influenced by heat-induced changes in the nutrient status of the soil. Moreover, post-wildfire pioneer plant species may alter soil properties, and thereby, impact subsequent plant recruitment. Our study compared the growth and elemental content of big sagebrush (Artemisia tridentata), squirreltail (Elymus elymoides), cheatgrass (Bromus tectorum), and Indian ricegrass (Achnatherum hymenoides), grown under greenhouse conditions in post-wildfire and similar unburned soil. We also examined soil attributes following plant growth. Cheatgrass and squirreltail, grown in post-wildfire soil, had significantly (p≤0.05) greater aboveground mass than plants grown in unburned soil. As compared with unburned soil, post-wildfire soil engendered the following significant (p≤0.05) differences in leaf elemental content: 1) big sagebrush had higher levels of P and lower levels of Mn; 2) squirreltail accumulated more P and N; and 3) all grass species had higher SiO2 content. Following harvest of plants, post-wildfire soil generally contained significantly (p≤0.05) more KCl-extractable ortho-P, NH inf4 + , and SO 4 − , than unburned soil. Plant growth in both burned and unburned soils fostered a significant (p≤0.05) increase in the bicarbonate-extractable pool of P as compared with unplanted controls. Soil Kjeldahl-N was significantly (p≤0.05) greater after plant growth in burned treatments as compared with the control. This study demonstrates that post-wildfire soil can have a stimulatory effect on plant growth for some species. Squirreltail deserves consideration as a post-wildfire revegetation species. Furthermore, pioneer plant growth following wildfires can attenuate soil properties and therefore influence plant succession.
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    URL: http://dx.doi.org/10.1007/BF00010108
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    Subterranean clover decline in permanent pastures in north-eastern Victoria (1994)
    Springer
    Plant and soil 164 (1994), S. 231-241 
    Details
    ISSN: 1573-5036
    Keywords: phosphorus ; root disease ; soil acidity ; subterranean clover ; yield decline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experimental sites were established at two locations in north-eastern Victoria to define factors limiting the establishment and growth of Trifolium subterranean L. (subterranean clover). Liming the soil, seed inoculation and fungicide application were used in renovating subterranean clover pasture on two acidic soils (Longwood: brown/grey sandy loam DY 3.14 and Seymour: grey brown light clay DY 3.22, Northcote classification) with mean annual rainfall of 650 mm and 600 mm respectively. Soil acidity, low available soil phosphorus and plant disease were identified as factors limiting clover yield on these soils. Significant yield responses to lime (35–140%) were obtained with subterranean clover at both sites, with corresponding decreases in Al in the 0–10 cm soil horizon. Liming the soil, when combined with seed inoculation, increased the number and effectiveness of root nodules at both sites. Soil P available for plant growth was low at both sites (6.1 and 8.4 μg g−1) resulting in sub-optimal P concentrations in the clover herbage (45 mmol kg−1 at Longwood). Levels of root disease were low but Aphanomyces euteiches and Phytophthora clandestina (causal agents of lateral and tap root rot) were detected frequently on roots. Application of fungicide resulted in higher dry matter yields (p=0.05) at both sites. An assessment of the relative contributions of these limiting factors and the benefits to be obtained from better management would provide a clearer picture of the profitability and sustainability of this farming system.
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    URL: http://dx.doi.org/10.1007/BF00010075
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    Phosphorus depletion in the rhizosphere as influenced by soil moisture (1994)
    Springer
    Plant and soil 159 (1994), S. 213-218 
    Details
    ISSN: 1573-5036
    Keywords: concentration gradient ; diffusion ; phosphorus ; rhizosphere ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the influence of soil moisture on phosphorus (P) depletion in the rhizosphere, maize (Zea mays cv. Trak) was pre-grown in vermiculite filled-PVC tubes for 9 days and then the plants with the tubes were transplanted into soil columns maintained at two soil moisture levels (θ) of 0.14 and 0.20 cm3 cm−3 for 10 days. The soil columns were separated at 1 cm depth by a nylon screen of 53 μm inner mesh size, into 1 cm soil layer above and 3 cm soil column below screen. A root mat developed over the screen, but root hairs only could penetrate it. Regardless of the soil moisture level in the columns, and adequate and equal water and nutrients supply was maintained via wicks from an external nutrient solution to the plant roots in vermiculite. After 10 days, the soil columns were separated from the root mats, quickly frozen in liquid nitrogen and sliced into thin layers (0.2mm) using a refrigerated microtome to give soil samples at defined distances from the root mats for analyses. Lower soil moisture (θ=0.14) resulted in narrower and steeper depletion profile of 0.5 M NaHCO3 extractable P (NaHCO3-Pi) as compared to higher soil moisture (θ=0.20). Depletion of P in soil solution in the immediate vicinity of root mats did not differ much but the extension of the depletion zones was 0.10 cm at θ=0.14 and 0.20 cm at θ=0.20. The depletion up to 0.05cm with θ=0.14 and up to 0.07 cm with θ=0.20 was uniform, and may be attributed to the depletion in the root hair zone. Beyond the root hair zones, the theory of diffusion and mass flow was able to explain the observed differences in shape and extent of the P depletion profiles at the two soil moisture levels.
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    URL: http://dx.doi.org/10.1007/BF00009283
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    Effect of elevated CO2 on mycorrhizal colonization of loblolly pine (Pinus taeda L.) seedlings (1994)
    Springer
    Plant and soil 165 (1994), S. 81-88 
    Details
    ISSN: 1573-5036
    Keywords: carbohydrates ; ectomycorrhizae ; elevated CO2 ; phosphorus ; Pinus taeda L. ; Pisolithus tinctorius (Pers.) Coker & Couch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Interactive effects of elevated atmospheric CO2 and phosphorus supply on mycorrhizal colonization rates were investigated using loblolly pine (Pinus taeda L.) seedlings from Florida and coastal North Carolina. Seedlings from both populations were grown in greenhouses maintained at either 35.5 Pa or 71.0 Pa CO2. In both CO2 treatments, seedlings were grown in a full factorial experiment with or without mycorrhizal inoculum and with an adequate or a limiting supply of phosphorus. Seedlings were harvested 60, 90 and 120 days after emergence and at each harvest root subsamples were examined to determine the percent of fine roots that were mycorrhizal. Additionally, root carbohydrate and nutrient levels were measured at each harvest. Root starch, sugar and total non-structural carbohydrate (TNC) concentrations were increased by growth in elevated CO2 and decreased by mycorrhizal colonization. Phosphorus stress decreased root starch concentrations, increased root sugar concentrations and did not significantly affect TNC concentrations. However, despite significant effects on root carbohydrate levels, there were generally no significant treatment effects on mycorrhizal colonization. Additionally, at all harvests, root starch and sugar concentrations were not correlated with percent of fine roots that were mycorrhizal. These results suggest that although elevated CO2 may significantly increase root carbohydrate levels, the increases may not affect the percent of fine roots that are mycorrhizal.
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    URL: http://dx.doi.org/10.1007/BF00009965
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    Enhanced root system C-sink activity, water relations and aspects of nutrient acquisition in mycotrophic Bouteloua gracilis subjected to CO2 enrichment (1994)
    Springer
    Plant and soil 165 (1994), S. 139-146 
    Details
    ISSN: 1573-5036
    Keywords: blue grama ; Bouteloua gracilis ; C4 grass ; CO2 enrichment ; mycorrhizae ; nitrogen ; phosphorus ; VAM ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to better elucidate fixed-C partitioning, nutrient acquisition and water relations of prairie grasses under elevated [CO2], we grew the C4 grass Bouteloua gracilis (H.B.K.) lag ex Steud. from seed in soil-packed, column-lysimeters in two growth chambers maintained at current ambient [CO2] (350 μL L−1) and twice enriched [CO2] (700 μL L−1). Once established, plants were deficit irrigated; growth chamber conditions were maintained at day/night temperatures of 25/16°C, relative humidities of 35%/90% and a 14-hour photoperiod to simulate summer conditions on the shortgrass steppe in eastern Colorado. After 11 weeks of growth, plants grown under CO2 enrichment had produced 35% and 65% greater total and root biomass, respectively, and had twice the level of vesicular-arbuscular mycorrhizal (VAM) infection (19.8% versus 10.8%) as plants grown under current ambient [CO2]. The CO2-enriched plants also exhibited greater leaf water potentials and higher plant water use efficiencies. Plant N uptake was reduced by CO2 enrichment, while P uptake appeared little influenced by CO2 regime. Under the conditions of the experiment, CO2 enrichment increased root biomass and VAM infection via stimulated growth and adjustments in C partitioning below-ground.
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    URL: http://dx.doi.org/10.1007/BF00009970
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    Growth response and phosphorus uptake of rye with long and short root hairs: Interactions with mycorrhizal infection (1994)
    Springer
    Plant and soil 167 (1994), S. 247-254 
    Details
    ISSN: 1573-5036
    Keywords: efficiency ; Glomus intraradices ; phosphorus ; root hair ; rye ; Secale cereale L. ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant growth and phosphorus (P) uptake of two selections of rye (Secale cereale L.) differing in length of root hairs, in response to mycorrhizal infection were investigated. Rye plants with short root hairs (SRH) had a greater length of root infected by Glomus intraradices (up to 32 m pot−1) than those with long root hairs (LRH) (up to 10 m pot−1). Application of P decreased the percentage of root length infected in both selections. In low-P soil, mycorrhizal infection increased shoot and root P concentration, especially in LRH plants. Generally, LRH had higher shoot dry weight than SRH plants. P uptake was increased both by LRH and by mycorrhizal infection. Differences in specific P uptake and P utilization efficiency between SRH and LRH plants were observed in non-mycorrhizal plants. With low P supply, P utilization efficiency (dry matter yield per unit of P taken up) of LRH plants increased with time. However, mycorrhizal infection reduced P utilization efficiency, particularly of SRH plants. SRH plants, which were agronomically less efficient (i.e. low dry matter yield at low P supply) were more responsive to either mycorrhizal infection or P addition than the LRH plants. No interaction was observed between mycorrhizal infection and root hair length.
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    URL: http://dx.doi.org/10.1007/BF00007951
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    Nutrient uptake in eastern deciduous tree seedlings (1994)
    Springer
    Plant and soil 160 (1994), S. 193-199 
    Details
    ISSN: 1573-5036
    Keywords: gaps ; ion uptake ; nitrogen ; nutrient acquisition ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tree seedlings that colonize large treefall gaps are generally shade-intolerant species with high potential relative growth rates. Nutrient availability may be significantly elevated in disturbance-induced gaps, however, little is known about the role of differences in nutrient uptake capacities of different species in structuring the community response to gap openings in eastern North American deciduous forests. Seven tree species were grown from seed under both a high and a low nutrient regime, and uptake kinetics of phosphate, ammonium, and nitrate were studied. Yellow birch, a species with intermediate shade tolerance and relative growth rate, had the highest maximum rates of uptake of all ions, while tulip tree, a gap-colonizing species with high relative growth rate, had the lowest rate of phosphate uptake and intermediate rates of ammonium and nitrate uptake. Beech and hickory, which have low relative growth rates and are not gap-colonizing species, had intermediate levels of nutrient uptake. There was no evidence that species with the highest maximum uptake rates measured at high supply concentrations had relatively low uptake at low nutrient supply concentrations. Although birch increased phosphate absorption capacity when grown under a low nutrient regime, this pattern did not hold for nitrate or ammonium uptake, and other species showed no change in nutrient uptake capacity according to nutrient growth regime. Clearly, factors other than nutrient absorption capacity, such as nutrient use efficiency or allocation to root vs. shoot biomass, underlie differences in species' capacities to colonize and maintain a high relative growth rate in canopy gaps.
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    URL: http://dx.doi.org/10.1007/BF00010145
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    Carbon cost of root systems: an architectural approach (1994)
    Springer
    Plant and soil 165 (1994), S. 161-169 
    Details
    ISSN: 1573-5036
    Keywords: carbon cost ; phosphorus ; Phaseolus vulgaris ; root architecture ; root growth ; root simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root architecture is an important component of nutrient uptake and may be sensitive to carbon allocational changes brought about by rising CO2. We describe a deformable geometric model of root growth, SimRoot, for the dynamic morphological and physiological simulation of root architectures. Using SimRoot, and measurements of root biomass deposition, respiration and exudation, carbon/phosphorus budgets were developed for three contrasting root architectures. Carbon allocation patterns and phosphorus acquisition efficiencies were estimated for Phaseolus vulgaris seedlings with either a dichotomous, herringbone, or empirically determined bean root architecture. Carbon allocation to biomass, respiration, and exudation varied significantly among architectures. Root systems also varied in the relationship between C expenditure and P acquisition, providing evidence for the importance of architecture in nutrient acquisition efficiency.
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    URL: http://dx.doi.org/10.1007/BF00009972
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    Effects of growth period, plant age and changes in solution aluminium concentrations on aluminium toxicity in wheat (1994)
    Springer
    Plant and soil 166 (1994), S. 21-30 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; growth period ; phosphorus ; plant age ; root length ; root width ; solution culture ; techniques ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of growth period (time between transplanting and harvesting), plant age at which aluminium (Al) was added to solution, changes in Al concentration, and solution culture techniques (monitoring and adjusting solution Al concentrations thrice weekly or weekly replacement of the solutions) were investigated using a low ionic strength (2.7×10−3 M) solution culture technique. The wheat (Triticum aestivum L.) cultivars Waalt (Al-tolerant) and Warigal (Al-sensitive), or the near isogenic lines bred from these cultivars (RR for the Al-tolerant line and SS for the Al-sensitive line) were grown. In all experiments and treatments, Al additions were required to maintain the nominal concentration. The decline in solution Al concentrations was partially attributed to formation of an Al-hydroxy-phosphate precipitate with an Al:P molar ratio of 2.8 to 4.0. Increasing the growth period from 14 to 28 days increased Al sensitivity in Warigal but not in Waalt. When plants were exposed to Al for the same time, increasing the age of the plants that Al was added to solution decreased sensitivity to Al. Differential Al tolerance between the two lines was evident when solutions were monitored thrice weekly or replaced weekly. However, the Al concentration required to reduce relative yield by a given amount when the solutions were replaced weekly was about twice that when the solutions were monitored. With a constant growth period of 28 days, increasing solution Al concentrations for 3 or more days resulted in decreased yields at harvest. The exact effect depended on the cultivar, plant part (tops or roots), when solution Al concentrations were increased and the duration of the increase. For example, increasing Al concentrations from 5 μM to 20 μM for 10 days reduced yield in the RR line by approximately 50% in the tops and 30% in the roots beyond the effect of 5 M but had no effect in the SS line due to yields already being low at 5 μM. Adding 10 μM Al to solution for 6 days at the beginning of the experiment reduced yield by 25% in the RR line and 50% in the SS line. In contrast, adding 10 μM Al for 6 days in the middle of the growth cycle had no effect on the RR line but reduced yield by approximately 25% in the SS line. These results show that growth period, the age of the plants at which Al is added and the technique used (monitored or weekly replacement) all need to be considered when comparing results from different experiments. These results also show that the Al concentrations in solution need to be regularly monitored in long term experiments.
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    URL: http://dx.doi.org/10.1007/BF02185477
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    Colonisation of wheat by VA-mycorrhizal fungi was found to be higher on a farm managed in an organic manner than on a conventional neighbour (1994)
    Springer
    Plant and soil 160 (1994), S. 33-40 
    Details
    ISSN: 1573-5036
    Keywords: organic agriculture ; phosphorus ; rock phosphate ; VA-mycorrhizas ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Levels of colonisation by vesicular-arbuscular (VA)-mycorrhizal fungi were compared between adjacent farms, one operated in a conventional manner and the other run according to organic farming principles. Wheat grown on the organic farm was found to have VA-mycorrhizal colonisation levels consistently 2 to 3 times higher than wheat on the conventional farm. Glasshouse and field trials indicated that the lower colonisation levels on the conventional farm were due to continual use of fertiliser containing soluble phosphorus (P). The fertiliser appeared to have an immediate negative effect on the rate of colonisation, and also appeared to have a long term negative effect through maintaining higher levels of soluble P in the soil, and by decreasing inoculum levels. Use of the relatively insoluble reactive rock phosphate fertiliser on the organic farm did not decrease levels of VA-mycorrhizas. Colonisation levels did not vary between wheat varieties, and herbicides and seed dressings were also not found to be having any significant effect on levels of colonisation.
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    URL: http://dx.doi.org/10.1007/BF00150343
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    Nutrient balances and phytoplankton dynamics in two agriculturally loaded shallow lakes (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 359-369 
    Details
    ISSN: 1573-5117
    Keywords: agriculture ; blue-green algae ; eutrophication ; internal loading ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The impact of agriculture was estimated on two shallow, eutrophic lakes, Lake Kotojärvi and Lake Villikkalanjärvi in southern Finland. The main emphasis was on phosphorus and nitrogen budgets and on the phytoplankton dynamics. Special attention was paid to internal P loading and blue-green algal blooms. The mean Tot-P load from agricultural land was 1.2 kg ha-1 a-1 in both basins and Tot-N loads were 19 kg ha-1 a-1 in L. Villikkalanjärvi and 12 kg ha-1 a-1 in L. Kotojärvi. The Tot-P input to L. Kotojärvi was on an average 0.62 g m-2 a-1 (per lake surface area), and the Tot-N input 9.1 g m-2 a-1. The corresponding inputs to L. Villikkalanjärvi were 3.1 and 57 g m-2 a-1, respectively. The annual variation followed the runoff volumes. About half of the Tot-P and one third of the Tot-N load was retained in L. Kotojärvi. In L. Villikkalanjärvi the retention was only 24% for Tot-P and 19% for Tot-N. The difference was very probably due to a longer theoretical retention time in L. Kotojärvi. In L. Villikkalanjärvi the mean concentration of Tot-P was 120 µg 1-1 and that of Tot-N 1700 µg 1-1 and the corresponding figures in L. Kotojärvi 67 and 990 µg 1-1, respectively. The mean chlorophyll a concentration was, however, higher in L. Kotojärvi (26 µg 1-1) than in L. Villikkalanjärvi (20 µg 1-1). This was probably due to an internal P load in L. Kotojärvi: in 1988 the internal load of dissolved P was estimated to be as much as twofold the external load. In L. Villikkalanjärvi the internal dissolved P load was only up to 50% of the external input. In L. Kotojärvi the high internal P load coupled with a low DIN:DIP ratio resulted in a strong blue-green algal bloom in the summer of 1988. In L. Villikkalanjärvi blue-green algae were observed only in small amounts. Even in August 1990, when the DIN:DIP ratio was low enough to favor the occurrence of blue-green algae, they contributed only up to 10–15% of the total phytoplankton biomass.
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    A diatom-phosphorus transfer function for shallow, eutrophic ponds in southeast England (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 391-410 
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    ISSN: 1573-5117
    Keywords: diatoms ; phosphorus ; palaeolimnology ; transfer function ; United Kingdom ; shallow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shallow ponds in southeast England are often eutrophic with high phosphorus concentrations. The aim of this study was to develop a diatom-phosphorus ‘transfer function’ to enable past phosphorus levels in such waters to be inferred from the sediment record. A water chemistry survey of 123 randomly chosen, shallow, artificial ponds in southeast England was carried out. Principal components analysis (PCA) revealed that phosphorus was an important environmental variable. A subset of 31 sites was selected along a total phosphorus (TP) gradient (winter TP range 7–1123 µg 1-1), in order to explore the relationship between the surface-sediment diatom assemblages and the contemporary water chemistry using canonical correspondence analysis (CCA). Annual mean TP was the most significant variable in explaining the variance in the diatom species data. Weighted averaging (WA) regression and calibration techniques were used to generate a transfer function, enabling annual mean TP (range 25–646 µg 1-1) to be inferred from the diatom species TP optima of 102 common taxa in the dataset (r 2 = 0.79; RMSE = 0.161; RMSE(boot) = 0.279; n = 30). The model was applied to fossil diatom assemblages in a sediment core from Marsworth Reservoir, Hertfordshire, a Site of Special Scientific Interest (SSSI), with currently high TP levels of 476 µg 1-1, to reconstruct past epilimnetic annual mean TP concentrations. The study shows that artificial, shallow waters can be suitable for palaeolimnological research and that it is possible to reliably infer lake water TP using the WA technique, across a large range of phosphorus concentrations. This method has the potential to provide limnologists, conservationists and water quality managers with an estimate of pre-enrichment phosphorus concentrations and an indication of the onset and development of eutrophication at a site. This information is essential for lake management strategies and restoration programmes.
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    Nutrient metabolism (C, N, P, and Si) in the trophogenic zone of a meromictic lake (1994)
    Springer
    Hydrobiologia 277 (1994), S. 17-39 
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    ISSN: 1573-5117
    Keywords: carbon ; phosphorus ; nitrogen ; silica ; sedimentation ; mineralization ; meromixis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dynamics of seston and dissolved elements in a meromictic lake with high concentrations of manganese and iron in the monimolimnion were studied through an annual cycle. This publication presents results for assimilation, sedimentation and recovery of nutrients (C, N, P, and Si) in the trophogenic zone. Phosphorus deficiency kept the productivity of the diatom dominated phytoplankton at an oligotrophic level. High concentrations of iron in influent streams and redistribution followed by precipitation of iron during periods of partial turnover removed phosphorus from the water. High concentrations of manganese and sulfate did not have the anticipated fertilizing effect, and recovery of nutrients from the depth of the lake was negligible. Mass balance calculations indicate that liberation of phosphorus from the sediments in the trophogenic zone was most important for the maintenance of primary production. 75% of carbon, 80% of nitrogen and 25% of phosphorus assimilated by the phytoplankton was mineralized in the trophogenic zone. Silica was effectively regenerated from the littoral zone during the decline of diatom blooms. Nitrogen and silica retention was 45% of the external load compared to 66% for phosphorus.
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    The importance of avian-contributed nitrogen (N) and phosphorus (P) to Lake Grand-Lieu, France (1994)
    Springer
    Hydrobiologia 279-280 (1994), S. 133-147 
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    ISSN: 1573-5117
    Keywords: eutrophication ; birds ; lake ; nitrogen ; phosphorus ; eutrophisation ; oiseaux ; lac ; azote ; phosphore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le plus grand lac de plaine français, Grand-Lieu, est actuellement largement eutrophisé. Le but de cette étude est d'estimer l'importation annuelle de N et P par les fientes des oiseaux qui s'alimentent à l'extérieur du lac, et de la comparer avec les apports des rivières alimentant le lac. Deux années sont comparées: 1981–82 et 1990–91. Les populations nicheuses (jusqu'à 956 couples de hérons cendrés et 136 couples de grands cormorans et 30 000 canards) et hivernantes (jusqu'à 17 000 canards, 1100 grands cormorans, 15 000 goélands et 2,4 millions d'étourneaux) ont respectivement importé 5800 kg de N total en 1981–82 et 7640 en 1990–91, soit 0,7% et 0,4% des entrées totales du système, et 2000 à 2530 kg de P total soit 2,4 et 6,6% des entrées. Les étourneaux sont responsables des trois quarts des apports d'azote par les oiseaux, et les canards de l'essentiel du reste, tandis que la part des étourneaux baisse pour le phosphore (36% en 1981–82 et 41% en 1990–91), au profit des Canards et des Hérons (respectivement 35% et 27% en 1981–82, 22% et 24% en 1990–91). Mais pendant la phase de croissance végétale (avril–septembre), la part des oiseaux monte jusqu'à 37% des entrées totales de phosphore. L'action localisée des colonies d'oiseaux piscivores est significative, avec une teneur de phosphore 42 fois plus grande dans l'eau sous la colonie qu'à l'extérieur des colonies. A l'échelle du l'ac, l'action actuelle globalement mineure des oiseaux sur les apports totaux d'azote et de phosphore est largement due à l'augmentation catastrophique des apports d'origine humaine (agriculture intensive et stations d'épuration). La teneur moyenne des rivières atteint désormais 10 mg l−1 de N (jusqu'à 23 mg en crue) et 394 mg m−3 de P (jusqu'à 468 mg en crue). Avant cette pollution généralisée, l'eau des rivières bretonnes ne contenait dans les années 1960 que 0,1 à 1,1 mg l−1 de N et 1 à 5 mg m−3 de P lors des périodes de débits maximum. A cette époque, les oiseaux représentaient probablement jusqu'à 36% des apports de N et 95% des apports de P dans les entrées du système lacustre.
    Notes: Abstract The largest natural lake in France, Grand-Lieu, has suffered eutrophication. The objective of the study was to estimate the annual input of nutrients (N, P) resulting from avian excrement, deposited by birds feeding out of the lake and returning to its waters for breeding or roosting, as compared to the input by the rivers that enter in the lake. Two years are compared: 1981–82 and 1990–91. About 1600–2000 breeding herons and cormorants, 20 000–33 000 wintering ducks, gulls and cormorants and 1–2.4 million starlings deposited about 5800 kg total N in 1981–82 and 7640 kg in 1990–91. Respectively, 2000 and 2530 kg total P were deposited over the same time periods. These represent 0.7% and 0.4% of the total N input of the lake and 2.4 and 6.6% of the total P input in 1981–82 and 1990–91. Starlings account for 74% of the N and mallards most of the rest. P input by starlings (36% in 1981–82, 41% in 1990–91), and by mallards and herons (35% and 27% in 1981–82 and 22% and 24% in 1990–91 respectively) plays an appreciable role among birds. During the plant growing period (April–September), the contribution by birds can increase to 37% of total P input of the lake. Piscivorous bird colonies concentrate Phosphorus 42 times more within the colony than outside the colony. Overall, the role birds play in total N and P input is relatively small due to very high inputs from human sewage and agriculture run off. The monthly mean concentration of the water of the two rivers reaches currently 10 mg l−1 of N (to 23 mg during peak floods) and 394 mg m−3 of P (to 468 mg during peak floods). Earlier, for example in the 1960's, water in Brittany only contained 0.1 to 1.1 mg 1−1 of N and 1 to 5 mg m−3 of P during the maximum flow period. At this time, birds could probably have represented annually up to 37% of the N input and up to 95% of the P input to the lake.
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    Different responses to changes in phosphorus, P, among lakes. A study of slopes in chl-a = f(P) graphs (1994)
    Springer
    Hydrobiologia 286 (1994), S. 27-36 
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    ISSN: 1573-5117
    Keywords: Lake ; eutrophication ; phytoplankton ; phosphorus ; non-linear interpolation ; chlorophyll-a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The least squares estimator of a linear regression coefficient βL will give an overall expression for the change in Δ with Δx. In fresh water ecology, however, subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\], of a parent population may have slopes which differ from the overall slope, βκ ≠ βL. By constructing frequency histograms for the set of angles: Arctang % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\],% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\]= para sa y and x% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiaadM% faliaadMgakiabgkHiTiaadMfaliaadQgakiaacMcacaGGVaGaaiik% aiaadIhaliaadMgakiabgkHiTiaadIhaliaadQgakiaacMcaaaa!42F0!\[(Yi - Yj)/(xi - xj)\], i 〈 j, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEaSGaam% yAaOGaeyiyIKRaamiEaSGaamOAaaaa!3BAB!\[xi \ne xj\], peaks in the distribution may be identified and related to ecological phenomenon. To identify peaks we fit Gaussian distributions to the frequency histograms. For a set consisting of 142 observations of chlorophyll-a and total phosphorus (nutrient) concentrations (TP) from 16 lakes we found four Gaussian peaks corresponding to four subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\]k = 1,4. One group identified a response of chl-a to changes in TP which correspond approximately to the average slope found by least square regression (the slope was 0.49). The second group consisted of steeper response than the average (1.28). A third group showed that there is an enhanced proportion of cases where chl-a does not respond to TP (zero slope, all the three deep lakes 〉 10 m, included in the date set contributed to this group). The size of the last group, spanning a wide range of slopes, suggested that about 30% of the inter annual changes in chl-a is unrelated to TP. The results are compared to result obtained by simple least squares regression and to the Theil non-parametric slope estimator.
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    Chlorophyll-phosphorus relationship in acidified lakes of the High Tatra Mountains (Slovakia) (1994)
    Springer
    Hydrobiologia 274 (1994), S. 171-177 
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    ISSN: 1573-5117
    Keywords: chlorophyll ; phosphorus ; mountain lakes ; acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Concentrations of total phosphorus (TP) and chlorophyll a (CHLA) were measured in 28 lakes in the High Tatra Mountains (Slovakia) from 1983 to 1990. The relationship between log CHLA and log TP in the Tatra lakes is similar to relationships developed for lakes in other regions, but variation is higher. A part of this variation is caused by acidification of the lakes. In the lakes with pH between 4.9 and 6.3 the CHLA concentrations are often extremely low while TP concentrations decreased, but not as drastically.
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    Nutrient cycling in shallow, oligotrophic Lake Kvie, Denmark (1994)
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    Hydrobiologia 275-276 (1994), S. 267-276 
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    ISSN: 1573-5117
    Keywords: phosphorus ; redox potential ; sediment ; rhizosphere ; macrophyte ; lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of isoetids for the exchange of phosphorus between sediment and water was studied in the shallow Lake Kvie, Denmark. Vegetated sediments from the littoral zone (55% of lake area) were compared to unvegetated sediments from the littoral and profundal zone. Porewater concentration of soluble reactive phosphate (SRP) was in general low, however, different distributions were found in the three sediments. The vegetated littoral sediment showed highest conc. of SRP just below the surface and decreasing conc. with sediment depth. The SRP release was low on all stations ( 〈 40 µmol m-2 d-1). The observed release of SRP on the vegetated station was much lower than the calculated diffusional flux probably due to assimilation of P by isoetids and binding of SRP to oxidized Fe. The high redox potential in the rhizosphere was probably caused by oxygen excretion from roots. The annual P release from vegetated sediments were only 5% of the P requirements of the macrophytes. The efficient plant assimilation of SRP from the porewater resulted in a small SRP pool with a very fast turnover of P of 500–900 times per year. Both the effects of isoetids on the P cycle in littoral sediments and on the P budget of the entire lake indicate that this plant group is important for keeping lakes in an oligotrophic state.
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    Can Chara control phosphorus cycling in Lake Łuknajno (Poland)? (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 277-283 
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    ISSN: 1573-5117
    Keywords: phosphorus ; eutrophication ; Chara aspera ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Waters of Lake Łuknajno (623 ha, 3 m max. depth postglacial basin in Masurian Lakeland) are of meso-eutrophic type in spite of an intensive land impact and substantial phosphorus loading. The reason of this peculiarity is an abundance of 4 species of charophytes (Chara aculeolata, C. aspera, C. contraria and C. tomentosa) which dominate the submerged vegetation of the lake and yielded 417 g m-2 dry biomass in summer 1991. The plants have high potential for phosphorus uptake and accumulation as was checked in laboratory experiments. Due to this potential Chara can outcompete planktonic algae in mixed cultures at different mineral P supplies.
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    Phosphorus fluctuation in water and deposition into sediment within an emergent macrophyte stand (1994)
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    Hydrobiologia 275-276 (1994), S. 285-292 
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    ISSN: 1573-5117
    Keywords: phosphorus ; sediment ; lake littoral ; Equisetum fluviatile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seasonal fluctuation of phosphorus in water, and total phosphorus and different inorganic P fractions (extracted by NH4Cl, NH4F, NaOH and H2SO4) and organic P fraction (residual P) in surface sediment, were measured in the littoral of oligotrophic Lake Pääjärvi (southern Finland). After the emergence of Equisetum fluviatile L. shoots in mid June, water exchange between the littoral and pelagial area diminished and phosphorus concentrations in water and in surface sediment increased in the inner and mid littoral zones. Phosphorus pool in flocculent, ‘easily resuspensible’ sediment composed on average 62% of inorganic phosphorus and 38% of organic phosphorus. 63% of the inorganic phosphorus, on the average, was extracted from ‘apatite-P fraction’ 29% from ‘iron-P fraction’ 7% from ‘aluminum-P fraction’ and less than 1% from ‘loosely-bound P fraction’. During the growing season, net accumulation of sediment and phosphorus was measured only in the inner littoral zone whereas the outer littoral zones acted rather as a source of phosphorus for the pelagic area. The results of this study indicated that nutrient dynamics in littoral environment was through changes in flow environment greatly governed by the macrophytes.
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    Recent palaeolimnology of three shallow Danish lakes (1994)
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    Hydrobiologia 275-276 (1994), S. 411-422 
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    ISSN: 1573-5117
    Keywords: diatoms ; phosphorus ; weighted averaging ; lake sediments ; carbonates ; radionuclides ; mixing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent eutrophication histories of three shallow lakes (mean depths 〈3 m) were studied using palaeolimnological methods. Freeze-cores were dated using 210Pb, 137Cs, 134Cs and 241Am. Resultant chronologies were problematical at two sites (Væng Sø and Vesterborg Sø) due to sediment-water interface mixing, indicated by uniform 137Cs profiles over the surface 20–30 cm. Sediments at Langesø and Vesterborg Sø have a high carbonate content, which together with the high mixing rate have resulted in diatom dissolution below 30 cm at Vesterborg Sø. Diatom stratigraphy indicates relatively small biological changes at both Væng Sø and Langesø both lakes have been eutrophic for at least the last 150–200 years. Væng Sø is dominated by planktonic diatoms together with high percentages of benthic Fragilaria spp., and Langesø by planktonic diatoms, especially Cyclostephanos dubius and Stephanodiscus parvus. Epilimnetic phosphorus concentrations were inferred using weighted averaging; at Væng Sø the diatom-inferred TP (DI-TP) concentrations were close to observed values in the early 1980s, but failed to record the post-biomanipulation decrease to 55 μg l-1 after 1988, presumably due to the smoothing of the sediment record by resuspension and mixing. At Langesø two increases in DI-TP suggest a two-phase enrichment of the lake, initial eutrophication ∼ 1880, and hypertrophy after 1950. The recent DI-TP values are lower than the annual observed values, and reasons for this are discussed. Despite problems associated with sediment mixing, the sediment records of these shallow systems can still be used for monitoring and for environmental reconstructions.
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    High resolution measurements of sediment resuspension above an accumulation bottom in a stratified lake (1994)
    Springer
    Hydrobiologia 284 (1994), S. 43-57 
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    ISSN: 1573-5117
    Keywords: sediment ; resuspension ; lakes ; optical measurements ; transmissometer ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A detailed record of suspended particulate matter (SPM) concentrations in the benthic boundary layer (BBL) 1.5 m above an accumulation bottom and 13.5 m below the surface was obtained from frequent (30 min interval) beam attenuation measurements made with a Sea Tech transmissometer in the main basin of Lake Erken, a moderately deep (mean depth 9 m, maximum depth 21 m) dimictic lake in central Sweden. Concentrations of SPM (g m−3) were not as strongly correlated to the beam attenuation coefficient (c, [m−1]), as were concentrations of the inorganic SPM fraction. Apparently, this was caused by large optically inactive organic particles which significantly affected the measurements of SPM, but had little effect on the attenuation of light. When the water column was thermally stratified, SPM concentrations in the BBL showed a seasonal increase which was related to an increase in the thermocline depth. As the epilimnion deepened, there was also a marked increase in the occurrence of rapid and large changes in SPM concentration. After the loss of stratification, the amount of SPM and the temporal variability in its concentration was reduced. Since surface waves could not influence sediment resuspension at the depth of measurement, these data show the importance of internal waves in promoting sediment resuspension in areas of sediment accumulation. The relatively short period in each summer, when the thermocline reaches a sufficient depth to allow for resuspension over accumulation bottoms, can have important consequences for both the redistribution of lake sediments and the internal loading of phosphorus.
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    Bioavailability of phosphorus in agriculturally loaded rivers in southern Finland (1994)
    Springer
    Hydrobiologia 287 (1994), S. 179-194 
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    ISSN: 1573-5117
    Keywords: agriculture ; phosphorus ; bioavailability ; bioassays ; isotherms ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The potential bioavailability of phosphorus in agriculturally loaded rivers of southern Finland was determined by an algal bioassay and the release of the potentially bioavailable particulate P was estimated by sorption studies. According to the bioassay 0 to 13.2 per cent (mean 5.1%) of the particulate P in river water samples was potentially bioavailable. Dissolved reactive P (DRP) in river waters appeared to be totally bioavailable whereas the dissolved unreactive P appeared not to be utilized by algae. In addition to river waters two lake sediment samples were also assayed. In these samples 0 and 2.6% of the P was bioavailable. The potential bioavailability of particulate P in agriculturally loaded rivers obtained in this study was lower than that reported in studies from other countries. The difference was assumed to arise partly from methodological factors and partly from the nature of the Finnish soils. The EPC (equilibrium phosphate concentration) values indicated that during the period when most of the agricultural loading enters the lakes in Finland, potentially bioavailable P is not released from the particles because of the relatively high DRP concentration in the receiving waters. However, during the algal production period the DRP concentration in lakes decreases below the EPC and potentially bioavailable particulate P is desorbed. The increase in pH during this period may further enhance the desorption of P.
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    Scion-rootstock relationships with respect to height growth and foliar concentrations of nitrogen and phosphorus in reciprocal grafts of Pinus caribaea var. hondurensis (1994)
    Springer
    New forests 8 (1994), S. 71-79 
    Details
    ISSN: 1573-5095
    Keywords: foliage ; grafting ; nitrogen ; phosphorus ; Pinus caribaea ; rootstock ; scion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Both scion and rootstock clones significantly influenced scion elongation and concentrations of nitrogen and phosphorus in the scion foliage. Scion clone was the more important determinant. Scion clone × rootstock clone interactions were not significant. The ability of a clone to elongate as a scion was not correlated with its capacity to promote or retard scion elongation when used as a rootstock. Genetic differences in foliar nutrient concentrations appeared to reflect levels of nutrient demand, rather than the ability of roots to absorb nutrients. Nutrient demand of the rootstock can also explain negative correlations between nitrogen levels in rootstock clones and levels of both nitrogen and phosphorus in the scions. There was no significant relationship between scion elongation and foliar nitrogen concentrations of either rootstock or scion. The weak relationship between scion elongation and concentration of phosphorus in the rootstock apparently resulted from tissue dilution.
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    URL: http://dx.doi.org/10.1007/BF00034132
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    Assessment of nutrient availability and limitation using macroalgae (1994)
    Springer
    Journal of aquatic ecosystem stress and recovery 3 (1994), S. 27-34 
    Details
    ISSN: 1573-5141
    Keywords: nutrient limitation ; critical tissue concentrations ; nitrogen ; phosphorus ; macroalgae ; biomonitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Discs of the macroalga,Ulva lactuca L., were transplanted around an ocean outfall and at a reference site in Køge Bay, Denmark, to assess the influence of the outfall on the nutrient availability. At 2-wk intervals, samples were collected and analyzed for growth, nitrogen, and phosphorus content. The tissue concentrations of nitrogen and phosphorus decreased with distance to the outfall, showing that the tissue concentrations are suitable for monitoring nutrient availability in coastal areas and provide a time-integrated measure of the nutrient availability. The lowest tissue concentrations of nitrogen were recorded at the reference station, where the internal concentrations generally were below the critical concentration level, showing that nitrogen limited the growth. At the station located close to the outfall, the flux of nitrogen was sufficient to maintain the maximum growth rate. The tissue concentrations of phosphorus were only below the critical concentration level on one occasion, and the result showed a net uptake throughout the study period. It was concluded that in the Køge Bay, nitrogen was the main limiting factor for macroalgae growth during the summer. The applicability of tissue concentrations for assessment of nutrient availability is discussed and it is considered that the method, when evaluated against established critical concentrations, provides a valuable tool for assessing ecosystem health with regard to eutrophication.
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    URL: http://dx.doi.org/10.1007/BF00045154
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    Variable rates of phosphate uptake by shallow marine carbonate sediments: Mechanisms and ecological significance (1994)
    Springer
    Biogeochemistry 25 (1994), S. 127-146 
    Details
    ISSN: 1573-515X
    Keywords: carbonate sediments ; phosphate adsorption ; phosphorus ; phosphorus limitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We determined phosphate uptake by calcareous sediments at two locations within a shallow lagoon in Bermuda that varied in trophic status, with one site being mesotrophic and the other being more eutrophic. Phosphate adsorption over a six hour period was significantly faster in sediments from the mesotrophic site. Uptake at both sites was significantly less than that reported for a similar experiment on calcareous sediments in an oligotrophic lagoon in the Bahamas. The difference in phosphorus adsorption between our sites did not appear to be related to sediment characteristics often cited as important, such as differences in surface area (as inferred from grain size distributions), total organic matter content, or iron content. However, the sediment total phosphorus contents were inversely related to phosphorus uptake at our sites in Bermuda, and at the previously studied Bahamas site. We hypothesize that phosphate uptake in these calcareous sediments is a multi-step process, as previously described for fluvial sediments or pure calcium carbonate solids, with rapid initial surface chemisorption followed by a slower incorporation into the carbonate solid-phase matrix. Accordingly, sediments already richer in solid phase phosphorus take up additional phosphate more slowly since the slower incorporation of surface-adsorbed phosphate into the carbonate matrix limits the rate of renewal of surface-reactive adsorption sites. Although carbonate sediments are a sink for phosphate, and thereby reduce the availability of phosphorus for benthic macrophytes and phytoplankton in the shallow overlying water, phosphate uptake by these sediments appears to decrease along a gradient from oligotrophic to eutrophic sites. If our result is general, it implies a positive feedback in phosphorus availability, with a proportionately greater percentage of phosphorus loading being biologically available longer as phosphorus loading increases. This pattern is supported by the significantly higher tissue phosphorus content of the seagrass,Thalassia testudinum, collected from the eutrophic inner bay site. Over time, this effect may tend to cause a shift from phosphorus to nitrogen limitation in some calcareous marine environments.
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    URL: http://dx.doi.org/10.1007/BF00000882
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    Mycorrhizal dependency of micropropagated argan tree (Argania spinosa): II. Mineral nutrition (1994)
    Springer
    Agroforestry systems 27 (1994), S. 67-77 
    Details
    ISSN: 1572-9680
    Keywords: Argania spinosa ; micro-elements ; nitrogen ; phosphorus ; V.A. mycorrhization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'influence de la mycorhization V.A. sur la nutrition minérale de 2 clones d'Arganier (Argania spinosa) a été étudiée sur des plantules micropropagées in vitro poussant en conditions contrôlées. L'inoculation (qui augmentait la production de matière sèche d'un facteur 4,5) accroit également la teneur des plantes en phosphore, notamment dans les feuilles, et les plantes mycorhizées mobilisent 15 fois plus de phosphore que les plantes non inoculées. La teneur en azote est légèrement plus faible chez les plantes mycorhizées mais au total ces dernières exportent 3 fois plus d'azote. L'absorption des micro-éléments est aussi affectée par l'inoculation, qui accroit les teneurs des plantes en Fe, Zn et Cu. La nutrition minérale des deux clones étudiés semble affectée par le rapport racines/parties aériennes et d'autres caractéristiques génétiques, comme l'efficacité de translocation du fer. Ces résultats nous permettent de comprendre en quoi son système racinaire profond et mycorhizé permet à l'Arganier non seulement de pousser dans des zones arides aux sols pauvres, mais aussi d'améliorer la fertilité des couches supérieures du sol par l'effet litière.
    Notes: Abstract The influence of V.A. mycorrhization on mineral nutrition of 2 clones ofArgania spinosa was studied with in-vitro micropropagated plantlets grown in confined medium under controlled conditions. Inoculation, which increased dry matter production by a factor of 4.5, also increased P concentration in the plant, especially in the leaves, and the mycorrhizal plants mobilized 15 times more P than control plants. N concentration was slightly lower in mycorrhizal plants, but total N content was 3 times higher. Uptake of micro elements was also affected, inoculation increasing plant Fe, Zn and Cu content. Mineral nutrition in the test clones seemed affected by root/shoot ratio and other genetically-related characteristics, such as Fe translocation efficiency. These results help us to understand how its deep mycorrhizal root system might allowArgania spinosa not only to grow in infertile arid areas but also to improve top-soil fertility by a litter effect.
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    URL: http://dx.doi.org/10.1007/BF00704835
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    Influence of small river conditions on the abundance of Tubificidae (1994)
    Springer
    Hydrobiologia 278 (1994), S. 129-131 
    Details
    ISSN: 1573-5117
    Keywords: small rivers ; water contamination ; Tubificidae ; bacteria ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two small rivers, the Yerik and Nezhegolyok, were studied seasonally in 1979–1980. Increase in concentration of nitrogen and phosphorus compounds in the river water as well as proliferation of enterococci and enterobacilli favoured the abundance of Tubificidae while, at the same time, their numbers were reduced by chironomids and leeches.
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    URL: http://dx.doi.org/10.1007/BF00142320
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    Assessment of eutrophication in Loch Lomond by desk analysis (1994)
    Springer
    Hydrobiologia 290 (1994), S. 51-52 
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    ISSN: 1573-5117
    Keywords: Loch Lomond ; Scotland ; eutrophication ; phosphorus ; loss coefficients ; chlorophyll
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphorus and chlorophyll a levels were predicted for Loch Lomond from desk-derived P loss coefficients and flushing rates related according to existing eutrophication models. These were in close keeping with measured values.
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    URL: http://dx.doi.org/10.1007/BF00008952
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    Nutrient uptake in mycorrhizal symbiosis (1994)
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    Plant and soil 159 (1994), S. 89-102 
    Details
    ISSN: 1573-5036
    Keywords: copper ; ectomycorrhizas ; hyphal uptake ; phosphorus ; vesicular-arbuscular mycorrhizas ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The role of mycorrhizal fungi in acquisition of mineral nutrients by host plants is examined for three groups of mycorrhizas. These are; the ectomycorrhizas (ECM), the ericoid mycorrhizas (EM), and the vesicular-arbuscular mycorrhizas (VAM). Mycorrhizal infection may affect the mineral nutrition of the host plant directly by enhancing plant growth through nutrient acquisition by the fungus, or indirectly by modifying transpiration rates and the composition of rhizosphere microflora. A capacity for the external hyphae to take up and deliver nutrients to the plant has been demonstrated for the following nutrients and mycorrhizas; P (VAM, EM, ECM), NH4 + (VAM, EM, ECM), NO3 - (ECM), K (VAM, ECM), Ca (VAM, EM), SO4 2- (VAM), Cu (VAM), Zn (VAM) and Fe (EM). In experimental chambers, the external hyphae of VAM can deliver up to 80% of plant P, 25% of plant N, 10% of plant K, 25% of plant Zn and 60% of plant Cu. Knowledge of the role of mycorrhiza in the uptake of nutrients other than P and N is limited because definitive studies are few, especially for the ECM. Although further quantification is required, it is feasible that the external hyphae may provide a significant delivery system for N, K, Cu and Zn in addition to P in many soils. Proposals that ECM and VAM fungi contribute substantially to the Mg, B and Fe nutrition of the host plant have not been substantiated. ECM and EM fungi produce ectoenzymes which provide host plants with the potential to access organic N and P forms that are normally unavailable to VAM fungi or to non mycorrhizal roots. The relative contribution of these nutrient sources requires quantification in the field. Further basic research, including the quantification of nutrient uptake and transport by fungal hyphae in soil and regulation at the fungal-plant interface, is essential to support the selection and utilization of mycorrhizal fungi on a commercial scale.
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    URL: http://dx.doi.org/10.1007/BF00000098
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    Desorption and plant-availability of phosphate sorbed by some important minerals (1994)
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    Plant and soil 162 (1994), S. 89-97 
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    ISSN: 1573-5036
    Keywords: desorption ; phosphorus ; rice ; variable-charge mineral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted to study the desorption characteristics and plant-availability of phosphate sorbed by some important variable-charge minerals including kaolinite, goethite and amorphous Al oxide. Phosphate desorption from the complexes of goethite-P, kaolinite-P and Al oxide-P by equilibration with 0.02M KCl, resin or some commonly used chemical extractants was slow compared to desorption from a permanent-charge mineral (montmorillonite). However, rice plants were not observed under P deficiency in a pot trial with a phosphate-mineral complex as the only P source for both the permanent-charge mineral and the variable-charge minerals at either 50% or 100% sorption saturation with the exception of goethite-P at 50% saturation. In the exceptional goethite-P treatment, plant P concentration (1.0 g kg−1) was on the threshold of P deficiency. From 15% to 31% of the applied P was recovered by the plants within a growing period of three months, depending on sorption saturation and mineral type. Both the dry matter yield and P uptake decreased with decreasing sorption saturation for all the tested complexes except for Al oxide-P100 (100% saturation). In the case of Al oxide-P100, Al toxicity may have occurred, for poor root growth and high Al concentration in the plants were observed. The effect of sorption saturation on the yield and P uptake of plant was obvious for kaolinite and goethite but not very significant for montmorillonite. Based on the recovery of applied P, the plant-availability decreased in the following order: kaolinite-P100 〉 goethite-P100 〉 Al oxide-P50 〉 montmorillonite-P100 〉 montmorillonite-P50 〉 kaolinite-P50 〉 goethite-P50. Fractionation of the sorbed P before and after plant uptake showed that most of the P uptake originated from the resin-exchangeable P fraction in montmorillonite-P complex, but came mainly from NaOH-extractable fractions in goethite-P complex, whereas all the resin-P, NaHCO3-P and NaOH-P fractions in kaolinite- and amorphous Al oxide-P complex made a contribution to P uptake.
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    Selection for improved adaptation of white clover to low phosphorus and acid soils (1994)
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    Euphytica 77 (1994), S. 243-250 
    Details
    ISSN: 1573-5060
    Keywords: Acid soils ; phosphorus ; selection ; Trifolium repens ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A total of 490 white clover genotypes were grown in competition withAgrostis tenuis and repeatedly defoliated, in a glasshouse trial. The percentage change in shoot yield from the first to the last harvest (harvest 6) was negatively correlated with the soil-P level from which ecotypes were collected. High- and low-yielding genotypes were selected from this study and compared in a field trial on a low-P soil (12 mg Olsen P/kg soil), in a grazed mixed species sward. Over the first year there was no significant difference in spread into the sward, and over three years no significant difference in persistence. Selection in glasshouses for yield is unlikely to improve edaphic stress tolerance in the field. In a field study in New Zealand, comparison of six ecotype populations showed that after one year the highest-spreading population had been collected from a low-P soil while the lowest spreading population came from a high-P soil, although the correlation between spread and soi-P from which ecotypes were collected was not significant (r=−0.67 p〉0.05). However, in another field trial in England it was shown that populations collected from low-P soils not only outyielded those, collected from high-P soils but that they also responded less to added P. It was concluded that populations collected from low-P soils will be a useful source of germplasm to identify genotypes adapted to low-P soils. Successful identification of such genotypes is most likely to be made in the field rather than in controlled more artificial environments.
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    URL: http://dx.doi.org/10.1007/BF02262637
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    The role of extracellular calcium in pregnancy-induced attenuation of phenylephrine contraction in rat aorta with functional endothelium (1994)
    Springer
    Journal of comparative physiology 164 (1994), S. 81-87 
    Details
    ISSN: 1432-136X
    Keywords: Vascular smooth muscle ; Phenylephrine-induced contraction ; Pregnancy ; Aorta ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effect of pregnancy on the supply of calcium ions for the contractile responses of rat aortic rings to phenylephrine was investigated. The contractility of intact aortic rings from pregnant rats, compared with that of similar rings from non-pregnant rats, to phenylephrine and potassium chloride was significantly decreased. Contractions of rings from non-pregnant rats, pretreated with phenylephrine or potassium chloride, in response to calcium chloride were greater than those of similarly treated rings from pregnant rats. When the concentration of calcium chloride in the medium bathing the rings was reduced to 0.8 mmol·l-1, the contractile response to phenylephrine was significantly (P〈0.005) inhibited in rings from both pregnant and non-pregnant rats but to a greater extent in rings from non-pregnant rats. Contractions of aortic rings from pregnant rats in response to phenylephrine in calcium-free medium were similar to those of rings from non-pregnant rats, suggesting equal dependence on calcium from intracellular stores. The results suggest that pregnancy decreased the response to calcium influx into the aortic smooth muscle cells through both receptor-and voltage-operated calcium entry pathways. Since de-endothelialisation reversed the pregnancy-induced diminished contraction to phenylephrine, it is likely that pregnancy interferred with contractions induced by activation of receptors with phenylephrine through enhanced production of endothelium-derived relaxing factor(s).
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    Postprandial thermogenesis of rats with glutamate induced obesity in relation to energy intake (1993)
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    European journal of nutrition 32 (1993), S. 71-73 
    Details
    ISSN: 1436-6215
    Keywords: Rat ; glutamate-induced obesity ; postprandial thermogenesis ; Ratte ; Glutamat-induzierte Adipositas ; postprandiale Thermogenese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Bei 4 Monate alten Ratten mit Glutamat-induzierter Adipositas wurde die postprandiale Thermogenese über 8 h nach Fütterung von 300, 450 und 600 kJ/kg0,75 einer Pellet-Diät mittels indirekter Kalorimetrie in computergesteuerten Stoffwechselkäfigen mit offenem Kreislauf bestimmt. Bei den adipösen Tieren war die postprandiale Thermogenese nach Aufnahme von 600 kJ/kg0,75 (oberhalb des Energieerhaltungsbedarfs) signifikant auf 40% der Thermogenese der Kontrolltiere reduziert (12,0 gegenüber 31,5 kJ/kg0,75×8 h). Es wird geschlußfolgert, daß die Ratte mit Glutamat-induzierter Adipositas als ein Tiermodell mit beeinträchtigter fakultativer Thermogenese anzusehen ist, die hauptsächlich durch eine Verminderung der sympathischen adrenergen Aktivität verursacht ist.
    Notes: Summary Postprandial thermogenesis was estimated in 4-month-old male rats with glutamate induced obesity after being fed with 300, 450 and 600 kJ/kg0.75 of a pellet diet, respectively by indirect calorimetry in computer-controlled open circuit metabolic cages over 8 h. After an intake of 600 kJ/kg0.75 (above the maintenance energy requirement) postprandial thermogenesis was significantly reduced in the obese animals to about 40% of control rats (12.0 versus 31.5 kJ/kg0.75×8 h). It is concluded that the glutamate obese rat can be accepted as an animal model with impaired facultative thermogenesis, mainly caused by a reduction of sympathetic adrenergic activity.
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    Sustained release of salmon calcitonin in vivo from lactide: Glycolide copolymer depots (1993)
    Springer
    Calcified tissue international 52 (1993), S. 361-364 
    Details
    ISSN: 1432-0827
    Keywords: Calcitonin ; Sustained release ; Copolymer depot ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Studies were carried out to determine whether monolithic depot formulations, prepared using lactide:glycolide copolymers, could be used to administer salmon calcitonin (sCT) to rats in vivo. Formulations containing 2, 5, or 10% (w/w) sCT were administered subcutaneously to female Wistar strain rats. Release of sCT was determined by measurement of peptide in plasma using a specific radioimmunoassay and by measurement of residual sCT in the depots after recovery at postmortem. Plasma calcium concentrations and cumulative weight gain of the animals were used to measure pharmacological effects of the released sCT. Release of sCT from the depots was controlled by the copolymer and was sustained for periods up to 10 days. However, the release of sCT from the depots did not significantly alter plasma calcium concentrations, and effects on cumulative weight gain were small and transient. Peptide loading of the formulations was shown to modify sCT release. Maximal release of sCT from depots containing 10% peptide occurred over a 7 to 14-day period postadministration, with 5% sCT release occurred between days 11 and 14, and with 2% sCT, the period of maximal release was between days 11 and 18. Release of peptide from the depots was essentially complete by 21 days postadministration irrespective of the peptide loading. These data suggest that lactide:glycolide copolymer depots may have application for the convenient clinical administration of sCT in metabolic bone diseases.
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    Mechanical properties, bone mineral content, and bone composition (collagen, osteocalcin, IGF-I) of the rat femur: Influence of ovariectomy and nandrolone decanoate (anabolic steroid) treatment (1993)
    Springer
    Calcified tissue international 53 (1993), S. 269-277 
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    ISSN: 1432-0827
    Keywords: Bone ; Nandrolone decanoate ; Ovariectomy ; Bone mechanics ; IGF-I ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Nandrolone decanoate (ND) is an anabolic steroid with a positive effect on bone mass in osteoporotic patients. The mechanism of action, (i.e., reduction of bone resorption and/or Stimulation of bone formation), the ultimate effect on mechanical properties, and the most effective dosage are not yet clear. To address these issues, dose-related effects of the long-term effect of ND on Serum and bone biochemistry, bone mineral content, and bone mechanical properties in ovariectomized (OVX) rats (12 weeks old at the Start of the experiment) were Studied for 6 months. The results were compared with those obtained in agematched, intact, and OVX rats. OVX caused in the femur a significant increase in net periosteal bone formation and net endosteal bone resorption of bone collagen content and torsional strength, and of Serum alkaline phosphatase, osteocalcin, and insulin-like growth factor-I (IGF-I) levels, whereas cortical bone density and calcium/creatinine and phosphorus/creatinine in 24-hour urine were Significantly reduced. Treatment of OVX rats with 1 mg ND/14 days resulted in a Significant increase in periosteal bone formation, femur length, cortical and trabecular bone mineral content and density, torsion stiffness and Strength, and bone IGF-I content, and a decrease in Serum osteocalcin, urinary calcium/creatinine levels, and bone collagen content compared with OVX controls. The higher ND dosage of 2.5 mg/14 days did not improve the results. ND treatment did not reverse all changes induced by OVX to the level of the intact controls. These results indicate that ND acts as an antiresorptive drug and as a bone formation Stimulating drug. Furthermore, the increased bone mass and bone mineral density is associated with improved bone Strength and stiffness and the presence of an increased amount of IGF-I. IGF-I is a growth factor considered to play a role in the maintenance of normal skeletal balance by a paracrine or autocrine mechanism.
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    URL: http://dx.doi.org/10.1007/BF01320913
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    The effects of the aminobisphosphonate alendronate on thyroid hormone-induced osteopenia in rats (1993)
    Springer
    Calcified tissue international 53 (1993), S. 278-282 
    Details
    ISSN: 1432-0827
    Keywords: Hyperthyroidism ; Osteopenia ; Bisphosphonate ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Hyperthyroidism, either endogenous or iatrogenic, leads to increased bone turnover and osteopenia. This study was conducted to examine (1) whether thyroid hormone excess in rats causes bone changes similar to those seen in patients with hyperthyroidism, and (2) the effects of the aminobisphosphonate alendronate on the thyroid hormone-induced bone changes. Sprague-Dawley male rats, divided into four groups, received L-thyroxine (T4) 250 μg/kg/day (+T4) or vehicle (-T4) subcutaneously six times per week and alendronate 1.75 mg/kg (+ALN) or vehicle (-ALN) orally twice a week. Rats were sacrificed after 3 weeks of treatment, blood samples were analyzed for serum T4, triiodo-L-thyronine (T3), and osteocalcin, and the proximal tibiae were processed for histomorphometric analysis. Serum T4 and T3 levels measured 20–24 hours after the last injection were 2 to 2.5-fold higher in +T4 groups than in-T4 groups. Serum osteocalcin was significantly (P 〈 0.05) higher in +T4/-ALN group than in the other groups, which were not statistically different from each other. T4 treatment (+T4/-ALN) significantly decreased the amount of cancellous bone volume (-45%) and increased osteoid surface (+254%), osteoblast surface (+111%), and osteoclast surface (+176%) relative to control values. Alendronate increased the bone volume above control values in both T4-treated (+ T4/ +ALN) and untreated (-T4/ +ALN) rats, and prevented the T4-induced increase in bone turnover in +T4/+ALN rats. It is concluded that (1) excess thyroid hormone induces cancellous bone loss associated with high bone turnover in the rat, and (2) this bone loss can be prevented by alendronate through the inhibition of osteoclastic activity.
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    An experimental model of ascending pyelonephritis due toCandida albicans in rats (1993)
    Springer
    Mycopathologia 123 (1993), S. 149-154 
    Details
    ISSN: 1573-0832
    Keywords: Ascending pyelonephritis ; Candida albicans ; Experimental model ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We developed a new experimental model of ascendingCandida pyelonephritis in female rats with leukopenia and vesicoureteral reflux. Rats were treated transperitoneally with cyclophosphamide (200 mg/kg) to induce leukopenia 3 days before and transurethrally with diluted acetic acid solution to induce vesicoureteral reflux 1 day before inoculation ofCandida albicans strain, ATCC 10259 (containing 107 cells). Microscopy revealed acute pyelonephritis in whichCandida cells invaded from the fornix and/or papilla into the medulla within 3 days after inoculation. Between 7 and 28 days after inoculation, chronic pyelonephritis reached the cortex. The incidence of pyelonephritis increased gradually and was approximately 80% after 7 days.Candida colony counts of bladder urine specimens obtained by direct puncture were significantly greater in rats with pyelonephritis extending into the parenchyma than in those with pyelonephritis located along the pelvis (p〈0.01). These results suggest that this rat model shows the characteristic feature of ascending pyelonephritis due toC. albicans and that the severity ofCandida pyelonephritis can be estimated fromCandida counts of bladder urine.
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    Hydrology of the Peel-Harvey estuary catchment (1993)
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    Nutrient cycling in agroecosystems 36 (1993), S. 127-133 
    Details
    ISSN: 1573-0867
    Keywords: hydrology ; water balance ; phosphorus ; Streamflow ; Peel-Harvey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper discusses the land types, hydrologic characteristics and processes, and the major modification of these, in relation to mechanisms and magnitude of phosphorus losses to drains and riverine systems which discharge to the Peel-Harvey estuary. About 75% of the coastal plain part of the catchment is cleared of native vegetation and used for dryland, dairy and beef grazing. There are small areas devoted to irrigated pasture and commercial horticulture. Seventy-five percent of the soils of the catchment are sandy surfaced with a poor capacity to retain phosphorus. Though the area is flat, catchment water yields are high because of a large winter rainfall excess and low soil storage capacity. Drainage schemes have been constructed in much of the catchment to remove excess water quickly. This was required initially to allow agricultural expansion and is now important for protecting a growing infrastructure which serves the most populous region of Western Australia.
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    Fertilization of millet cv. Souna III in Senegal: dry matter production and nutrient uptake (1993)
    Springer
    Nutrient cycling in agroecosystems 35 (1993), S. 217-226 
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    ISSN: 1573-0867
    Keywords: calcium ; dry matter distribution ; fertilizer ; harvest index ; magnesium ; manure ; millet ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; Senegal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a fertilizer and manure experiment, millet was grown under four treatments (no fertilizer or manure, farmyard manure, chemical fertilizer, and both). Grain yield and total aboveground biomass production of the unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutrient availability, as amount of rainfall and its distribution were favourable. Results show only small differences in distribution of dry matter among the various plant organs between the best and the non-fertilized treatments. Nutrient supply from natural sources, defined as crop content of N, P, and K at maturity without fertilizer application, amounted to 104, 16 and 103 kg ha−1, respectively, which are very high values. Total uptake of calcium and magnesium is related to that of potassium, as the combined content of these three elements is linearly related to total aboveground biomass production. Minimum removal of nitrogen and phosphorus per ton grain dry matter amounts to 29 and 4kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural biomass and for maintenance of electro-neutrality is discussed.
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    Fertilizers and eutrophication in southwestern Australia: Setting the scene (1993)
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 95-103 
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    ISSN: 1573-0867
    Keywords: eutrophication ; phosphorus ; fertilizer ; Peel-Harvey estuary ; algal blooms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An excess of plant nutrients has caused serious eutrophication in aquatic ecosystems of southwestern Australia manifested by excessive growth and accumulation of green and bluegreen algae. Phosphorus is generally the limiting nutrient for algal growth and phosphatic fertilizers applied to nutrient-deficient, leaching, sandy soils are the main source of P, supplemented by rural industry point sources. Nitrogen is the limiting nutrient in marine embayments with little drainage from the land. Measures to reduce the load of P delivered to drainage include basing fertilizer application rates on soil testing for P and the use of less soluble P fertilizers. Catchment management plans are being implemented with community involvement to reduce P loads and maintain agricultural production. This introductory paper reviews the history of eutrophication in southwestern Australia and of studies into its causes, principally in the large Peel-Harvey estuary. It briefly summarises other papers in this special issue concerned with different aspects of the problem: how to fertilize the land without causing eutrophication.
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    Phosphorus retention and release from sandy soils of the Peel-Harvey catchment (1993)
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 115-122 
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    ISSN: 1573-0867
    Keywords: phosphorus ; retention ; release ; sandy soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to manage phosphorus (P) losses from soils to waterbodies, knowledge of the mechanisms through which P is retained or released from the soil is essential. Sandy soils of the Peel-Harvey catchment (Western Australia) were subjected to a range of environmental and management factors in the laboratory and field in order to gain an understanding of the mechanisms that affect the magnitude of P losses. Sandy soils accumulated P, despite having little sorption capacity, and this accumulation could be monitored by measuring an acid-extractable fraction. The potential, short-term P loss could be estimated by determination of water-soluble soil solution P prior to winter rains. An annual cycle of the change in arbitrarily defined soil-P pools is discussed in relation to environmental and management factors. Laboratory experiments indicated that P rundown and potential annual P loss in the absence of P fertilizers could be estimated using bicarbonate extractable P. Phosphorus losses were decreased by the application of fertilizers with a low content of water-soluble P. The low ability of sandy soils of the Peel-Harvey coastal catchment to retain P, when compared to other Western Australian soils, is because of low contents of clay minerals and iron and aluminium hydrous oxides.
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    What controls levels of dissolved phosphate and ammonium in surface waters? (1993)
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    Aquatic sciences 55 (1993), S. 132-142 
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    ISSN: 1420-9055
    Keywords: nitrogen ; phosphorus ; uptake ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved inorganic nutrient pools are small relative to particulate pools, and dissolved pools turnover rapidly. It has been observed that pools change little from day to day on the sampling scales usually employed. A simple model is presented where uptake and regeneration rates balance to cause a local steady state concentration for dissolved inorganic nutrients. Enrichment and dilution perturbation experiments with lake water support the idea of steady state nutrient concentrations. Although inorganic nutrient concentrations are often controlled by biota, the absolute concentrations present tell little about the activity of that biota.
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    Yeast single copy gene URP1 is a homolog of rat ribosomal protein gene L21 (1993)
    Springer
    Current genetics 23 (1993), S. 15-18 
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    ISSN: 1432-0983
    Keywords: Yeast ; Rat ; Ribosomal protein ; 60S Ribosomal subunit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This communication reports on a single-copy gene of Saccharomyces cerevisiae which is homologous to the rat ribosomal protein gene L21. The yeast and the rat genes show 59% identity in DNA sequences and in the predicted protein sequences. This yeast gene is, therefore, assumed to code for an as yet unassigned ribosomal protein (URP1). The URP1 open reading frame is 480 nucleotides long and can encode a protein of about Mr 18 200. Like most of the other known ribosomal protein genes, URP1 is interrupted by an intron in its 5′ terminal part and it is preceeded by upstream sequence elements which usually regulate transcription of these genes. Northern blot analysis reveals that the URP1 gene is actually expressed in vivo.
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    Neurofilaments in rat and cat spinal cord; a comparative immunocytochemical study of phosphorylated and non-phosphorylated subunits (1993)
    Springer
    Cell & tissue research 272 (1993), S. 249-256 
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    ISSN: 1432-0878
    Keywords: Spinal cord ; Motoneurones ; Dorsal horn ; Neurofilament ; Phosphorylation ; Immunocytochemistry ; Rat ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neurofilament immunoreactivity was examined in spinal cords of rats and cats with antibodies to all three subunits (68 kD, 155 kD and 200 kD) and to different phosphorylation states of 200 kD. NFHP-, an antibody against non-phosphorylated 200 kD, labelled all rat neuronal perikarya but failed to labet cat neurofilaments. In both species, the perikarya and processes of motoneurones were immunoreactive for all three subunits but most dorsal horn neuronal perikarya were not immunoreactive for 68 kD and 155 kD. Motoneuronal perikarya and proximal processes showed filamentous labelling for 68 kD but not for 155 kD in the rat, while in neither species did these show labelling with RT97, an antibody against a highly phosphorylated form of 200 kD; immunoreactivity for 200 kD was present in both filamentous (probably partially phosphorylated) and non-filamentous (non-phosphorylated) forms, but in dorsal horn neurones only the latter was present. Interpretations consistent with this data are: in rat and possibly also cat, motoneuronal neurofilaments consist of a 68 kD backbone with partially phosphorylated 200 kD sidearms, with both 155 kD and 200 kD (non-phosphorylated) subunits in a non-filamentous form; this neurofilament becomes more highly phosphorylated along the proximal processes. The dorsal horn neurones probably contain 200 kD in a non-filamentous form but may lack the other subunits.
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    Immunohistochemical localization of insulin-like growth factor 1 and 2 in the endocrine pancreas of rat, dog, and man, and their coexistence with classical islet hormones (1993)
    Springer
    Cell & tissue research 273 (1993), S. 249-259 
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    ISSN: 1432-0878
    Keywords: Endocrine pancreas ; IGF-1 ; IGF-2 ; Insulin ; Glucagon ; Somatostatin ; Pancreatic polypeptide ; Man ; Dog ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Immunohistochemical techniques were used to study the occurrence and distribution of insulin-like growth factor 1 (IGF-1) and IGF-2 in the pancreas of man, dog, and rat and their possible coexistence with insulin (INS), glucagon (GLUC), somatostatin (SOM) and pancreatic polypeptide (PP). All control experiments, including pre-absorption of the antisera with synthetic peptide hormones, indicated the specificity of the immunoreactions obtained. In all species investigated, IGF-2-immunoreactivity occurred exclusively in INS-immunoreactive cells as was found by the use of consecutive sections and double immunofluorescence on identical sections. In contrast, IGF-1-immunoreactivity co-existed with GLUC-immunoreactivity. In man, singular SOM-immunoreactive cells also contained IGF-1-immunoreactivity. Thus, IGF-1 and IGF-2 can be localized by means of immunohistochemistry in the mammalian pancreas, and can be shown to occur in different islet cell populations. It is presumed that IGF-1 derived from A-cells and/or D-cells acts on the B-cells in a paracrine manner. The co-existence of IGF-2-immunoreactivity and INS-immunoreactivity in the human, rat, and dog endocrine pancreas indicates that mammalian IGF-2 and INS genes are regulated simultaneously.
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    Atrial natriuretic peptide binding in rat placenta, yolk sac, decidua, and materal placental vessels (1993)
    Springer
    Cell & tissue research 272 (1993), S. 391-394 
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    ISSN: 1432-0878
    Keywords: ANP binding ; Yolk sac ; Decidua ; Maternal placental vessels ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Using in vitro autoradiography, binding sites of 125I-ANP (atrial natriuretic peptide) were localized in the rat placenta, visceral yolk sac, and decidua at 16, 18, and 20 days of gestation. There was diffuse binding over the labyrinthine region of the placenta and an intense binding over the decidual gland and visceral yolk sac. In the yolk sac, ANP localized over the cores of the villi where it may be involved with the regulation of transport across the membranes or the flow of blood through the vitelline vessels. Of particular interest was binding over the maternal blood vessels supplying the decidual region and placenta. Receptors were located on the endothelial cells and smooth muscle cells of the arteries and veins, indicating that ANP may be involved with regional regulation of blood flow to the placenta.
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    A monoclonal antibody disrupting cell-cell adhesion of rat ascites hepatoma cells (1993)
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    Cell & tissue research 273 (1993), S. 363-370 
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    ISSN: 1432-0878
    Keywords: Ascites hepatoma ; Adhesive factor ; Monoclonal antibody ; Cell membrane polarity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A cell surface-associated adhesive factor (AF) separated from differentiated rat ascites hepatoma AH136B cells (forming cell islands in vivo) has been highly purified by chromatography. AF is assumed to mediate the cell-cell adhesion essential to island formation of the hepatoma cells. A substance, immunologically crossreactive with AF, is present in the ascites fluid or culture medium of the AH136B cells. Because the substance is almost identical to AF in molecular weight and aggregation-promoting activity, it has been concluded that AF is released into the ascites fluid where it is concentrated. Monoclonal antibodies have been raised against AF purified from ascites fluid of AH136B cells. We have obtained a monoclonal antibody, coded MoAF-6D6, that strongly abolishes the aggregation-promoting activity of AF. When AH136B cell islands are incubated in the presence of Fab fragments of MoAF-6D6, cell detachment from the islands is evident within 24 h. Cell islands following 36-h culture show a distinct dissociation and islands completely lose their organization 48 h after culture. The dissociating effect of MoAF-6D6 is neutralized by the addition of AF. These results suggest that AF plays a significant role in the maintenance of cell islands.
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    Sowing date and phosphorus utilization by wheat (1993)
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    Plant and soil 155-156 (1993), S. 297-300 
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    ISSN: 1573-5036
    Keywords: efficiency ; phosphorus ; sowing time ; vernalization ; winter wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake and utilization of phosphorus (P) by cereal crops is influenced by the growing period of the crop. In this article the effect of sowing date on the utilization of P by wheat crops grown in southern NSW is reviewed. Crops sown early in the accepted sowing period require smaller inputs of P fertilizer to reach the maximum yield but produce grain with a higher concentration of P than crops sown late in the sowing season. For later sowings a higher rate of applied P is required to achieve the yield potential but this is not associated with a high grain P concentration or a high rate of removal of P from the soil. If grain with a high P concentration is required as seed for subsequent crops, then sowing early, even with little or no applied P fertilizer, is preferable, although crops sown early in the season are likely to remove more P from the soil than the amount applied in fertilizer.
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    Mycorrhizal responses of barley cultivars differing in P efficiency (1993)
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    Plant and soil 157 (1993), S. 97-105 
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    ISSN: 1573-5036
    Keywords: barley cultivars ; efficiency ; Glomus etunicatum ; Hordeum vulgare ; low temperature ; phosphorus ; response ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of this study was to investigate how barley cultivars which are different in dry matter yield at low phosphorus (P) supply (i.e. they differ in agronomic P efficiency) respond to mycorrhizal infection. In a preliminary experiment, six mycorrhizal fungi were tested for their ability to colonize barley (Hordeum vulgare L.) roots at a soil temperature of 15°C. Glomus etunicatum was the most effective species and was used in the main experiment. The main experiment was conducted under glasshouse conditions in which soil temperature was maintained at 15°C. Treatments consisted of a factorial arrangement of 8 barley cultivars, 2 mycorrhiza (inoculated and non-inoculated), and 3 rates of P (0, 10 and 20 mg kg-1). P utilization efficiency (dry matter yield per unit of P taken up) and agronomic P efficiency among the barley cultivars was significantly negatively correlated with mycorrhizal responses. However, the response to mycorrhizal infection was positively correlated with response to P application. Poor correlation was observed between P concentration when neither mycorrhiza nor P were supplied and the percentage of root length infected. The extent of mycorrhizal infection among the barley cultivars in soil without P amendment varied from 8.6 to 28.6%. Significant interactions between cultivar and P addition, and between mycorrhiza and P addition were observed for shoot dry weight but not root dry weight.
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    Nuclear magnetic resonance studies of the location and function of plant nutrients in vivo (1993)
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    Plant and soil 155-156 (1993), S. 45-55 
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    ISSN: 1573-5036
    Keywords: compartmentation ; cytoplasm ; 39K NMR ; maize ; nitrogen ; 14N NMR ; 15N NMR ; pea ; phosphorus ; potassium ; 31P NMR ; vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The cytoplasmic and vacuolar pools of ammonium, inorganic phosphate and potassium can be studied non-invasively in plant tissues using high resolution nuclear magnetic resonance spectroscopy. The techniques that allow these pools to be discriminated in vivo are described and their application to plants is reviewed with reference to the phosphorus, nitrogen and potassium nutrition of root tissues.
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    Preparation of iron oxide-impregnated filter paper for use in the Pi test for soil phosphorus (1993)
    Springer
    Plant and soil 151 (1993), S. 143-146 
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    ISSN: 1573-5036
    Keywords: iron oxide-impregnated filter paper ; phosphorus ; Pi soil test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficiency of recovery of P by iron oxide-impregnated filter paper, as used in the new Pi test for soil phosphorus, was found to depend on the method used for impregnating the paper with iron oxide and could range from as little as 28% to more than 98%. The greatest efficiency of recovery was obtained with filter papers which had been washed with deionised water following iron oxide-impregnation. These filter papers were also found to give the most reproducible results. ei]{gnB E}{fnClothier}
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    The effect of phytase on the availability of P from myo-inositol hexaphosphate (phytate) for maize roots (1993)
    Springer
    Plant and soil 154 (1993), S. 189-196 
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    ISSN: 1573-5036
    Keywords: bioavailability ; maize ; myo-inositol ; phosphorus ; phytase ; phytin ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of adding phytase to the root medium of maize plants on the P-availability of added myo-inositol hexaphosphate (phytin) has been studied in pot experiments. When 40 mM phytin-P in nutrient solution was incubated in quartz-sand for 15 days in the absence of plants, 80% of it could be recovered from the solution as soluble organic P. Maize plants growing on this mixture assimilated P from phytin at rates comparable to those from inorganic phosphate (Pi). At a lower addition rate (2 mM phytin-P) only 10% was recovered in the soil solution, and plant growth was severely limited by P. At this low phytin level, the addition of phytase (10 enzyme units per kg sand) increased the plants' dry weight yield by 32%. The relative increases of the Pi concentration in the solution and of the amount of P in the plants were even higher, indicating that the observed growth stimulation was due to an increased rate of phytin hydrolysis. The enzyme-induced growth stimulation was also observed with plants growing in pots filled with soil low in P, when phytin was added. However, on three different soils the addition rates of phytin and phytase necessary for obtaining a significant phytase effect were both about 10 times higher than those required in quartzsand. It is concluded that the P-availability from organic sources can be limited by the rate of their hydrolytic cleavage.
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    Mineral nutrient disorders of root crops of the Pacific: Preliminary observations on sweet potato (Ipomoea batatas) (1993)
    Springer
    Plant and soil 155-156 (1993), S. 263-267 
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    ISSN: 1573-5036
    Keywords: critical concentration ; magnesium ; manganese ; nitrogen ; phosphorus ; potassium ; solution culture ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Solution culture was used to characterise deficiencies or toxicities of several essential elements in Ipomoea batatas cv. Wanmun, and to define the critical concentrations of these elements in young mature leaves during vegetative growth. Tentative critical concentrations for deficiency, expressed on the basis of dry weight of leaf blade, were: nitrogen 3.8%, phosphorus 0.17%, potassium 2.4%, magnesium 0.12%, manganese 20μg/g and zinc 10μg/g. For manganese and zinc toxicities it was possible only to designate the range within which the critical concentration occurred. Visible symptoms are briefly described.
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    Phosphorus allocation in P-efficient and inefficient barley cultivars as affected by mycorrhizal infection (1993)
    Springer
    Plant and soil 155-156 (1993), S. 277-280 
    Details
    ISSN: 1573-5036
    Keywords: allocation ; barley ; efficiency ; Glomus etunicatum ; phosphorus ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was undertaken to investigate the effect of mycorrhizal infection on the allocation of phosphorus (P) in agronomically P-efficient (i.e. high yields at low P supply) and inefficient barley (Hordeum vulgare L.) cultivars. Four barley cultivars differing in agronomic P-efficiency were inoculated or not inoculated with Glomus etunicatum. Cultivars did not differ in percentage of root length infected. The concentration of P in roots of the inefficient cultivars was higher than that of the efficient cultivars. However, because of changes in root to shoot dry weight ratio and below-ground productivity, mycorrhizal infection significantly reduced the percentage of total plant P in roots of the inefficient cultivars. The distribution of P between root and shoot of P-efficient cultivars was not affected by mycorrhizal infection. Root to shoot dry weight ratio of the P-efficient cultivars was lower than that of the inefficient cultivars, and the decrease in the ratio following infection was significant in inefficient but not in P-efficient cultivars. This study indicates that mycorrhizal infection alters the allocation of P in inefficient cultivars and effectively improves the efficiency of P utilization with respect to shoot growth.
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    Root characteristics of native plant species in relation to the benefit of mycorrhizal colonization for phosphorus uptake (1993)
    Springer
    Plant and soil 155-156 (1993), S. 281-284 
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    ISSN: 1573-5036
    Keywords: benefit ; mycorrhizas ; phosphorus ; revegetation ; root characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We aimed to relate the root characteristics of native plants, with their benefit from mycorrhizal colonization, to assist in developing criteria for predicting plant response to mycorrhizal fungi in revegetated soils. The response of four plant species to VA mycorrhizal fungi was measured at increasing applications of phosphorus (P). The benefit of colonization for all species was large at low rates of P, but declined rapidly for some species at moderate P deficiency. Only then were length and fineness of roots and characteristics of root hairs useful in predicting relative benefit.
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    Phosphorus requirement and sources of nitrogen in three soybean (Glycine max) genotypes, Bragg, nts 382 and Chippewa (1993)
    Springer
    Plant and soil 151 (1993), S. 1-9 
    Details
    ISSN: 1573-5036
    Keywords: mutant ; 15N isotope dilution ; nitrogen fixation ; nitrogen (N) use efficiency ; nodules ; phosphorus ; phosphorus (P) use efficiency ; roots ; supernodulator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of different levels of soil phosphorus on nodulation, N2 fixation and growth of supernodulating soybean mutant, nts 382, its parent, Bragg, and soybean cultivar, Chippewa, were compared in a greenhouse study. The P rates were, 0, 30, 60 and 90 mg kg−1 soil (P0, P1, P2 and P3, respectively). The reduced shoot growth of nts 382 (25% at P0 and 17% at P3) could not be attributed to P deficiency, as nts 382 achieved near maximum yield at a lower P rate (P1) than Bragg (P2). The P response of Chippewa that produced the lowest shoot yield, was similar to that of Bragg. Root growth of nts 382 was more retarded than shoot growth (on average 50% that of Bragg), and yet absorbed a similar amount of total P as Bragg. Also, Chippewa that had the lowest root dry matter accumulated the highest P in the shoots. The data indicate that plant growth was influenced by differences in P use efficiency rather than differences in total P. In contrast to plant growth, nts 382 accumulated 26% more N than Bragg, and Chippewa accumulated a similar amount of N as Bragg. Thus again, Bragg used N most efficiently for growth. Soil N uptake was not governed by root biomass, and Chippewa absorbed more N from soil than both Bragg and nts 382 which absorbed similar amounts of soil N. Nodulation in nts 382 was significantly enhanced, being 528 and 892% greater than Bragg at P0 and P3, respectively, and nts 382 was the only cultivar whose nodulation was consistently enhanced by P addition. The percentage of N derived from fixation (% Ndfa) was not affected by supernodulation, but because of a greater accumulation of total N in nts 382, amount of N fixed (Ndfa) was on average 30% higher in nts 382 than Bragg. Also, while % Ndfa in either nts 382 or Bragg was not influenced by P addition, total N and consequently, Ndfa increased. However, for Chippewa which fixed the lowest N, both % Ndfa and Ndfa were increased by P addition. We conclude that although supernodulation had an adverse effect on shoot and root growth, these reductions could not be attributed to a reduced uptake of the two major plant nutrients, N and P, neither was there evidence that the mutation had caused a greater demand for these nutrients, other than for the greater requirement of P for nodulation. ei]{gnR O D}{fnDixon}
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    The ability of 16 ectomycorrhizal fungi to increase growth and phosphorus uptake of Eucalyptus globulus Labill. and E. diversicolor F. Muell. (1993)
    Springer
    Plant and soil 153 (1993), S. 155-164 
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    ISSN: 1573-5036
    Keywords: ectomycorrhizal fungi ; eucalypts ; growth response ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effectiveness of 16 fungal isolates in forming ectomycorrhizas and increasing the growth and phosphorus uptake of Eucalyptus globulus Labill. and E. diversicolor F. Muell. seedlings was examined in the glasshouse. Seedlings were grown in yellow sand at 2 phosphorus levels (4 and 12 mg P kg-1 sand). At the time of harvest (100 days), the non-inoculated seedlings and seedlings inoculated with Paxillus muelleri (Berk.) Sacc. and Cortinarius globuliformis Bougher had a low level of contamination from an unknown mycorrhizal fungi. Seedlings inoculated with Thaxterogaster sp. nov. and Hysterangium inflatum Rodway had developed mycorrhizas of the superficial type whereas Hydnangium carneum Wallr. in Dietr., Hymenogaster viscidus Massee & Rodway, Hymenogaster zeylanicus Petch, Setchelliogaster sp. nov., Laccaria laccata (Scop. ex. Fr.) Berk., Scleroderma verrucosum (Vaillant) Pers., Amanita xanthocephala (Berk.) Reid & Hilton, Descolea maculata Bougher and Malajczuk and Pisolithus tinctorius (Pers.) Coker & Couch formed typical pyramidal ectomycorrhizas. The dry weight of non-inoculated and inoculated E. globulus seedlings at 12 mg P kg-1 sand did not differ, whereas several isolates caused growth depression of E. diversicolor. By contrast, at 4 mg P kg-1 sand growth increases ranged from 0–13 times above that of non-inoculated seedlings. P. tinctorius produced the largest growth increase on both eucalypt species. In general, isolates which developed more extensive mycorrhizas on roots produced the largest growth responses to inoculation. Isolates which increased plant growth also increased phosphorus uptake by the plant. Seedlings inoculated with L. laccata and S. verrucosum retained more phosphorus in their roots than plants inoculated with the other fungal isolates.
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    Mycorrhizal responses of barley cultivars differing in P efficiency (1993)
    Springer
    Plant and soil 157 (1993), S. 97-105 
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    ISSN: 1573-5036
    Keywords: barley cultivars ; efficiency ; Glomus etunicatum ; Hordeum vulgare ; low temperature ; phosphorus ; response ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of this study was to investigate how barley cultivars which are different in dry matter yield at low phosphorus (P) supply (i.e. they differ in agronomic P efficiency) respond to mycorrhizal infection. In a preliminary experiment, six mycorrhizal fungi were tested for their ability to colonize barley (Hordeum vulgare L.) roots at a soil temperature of 15°C.Glomus etunicatum was the most effective species and was used in the main experiment. The main experiment was conducted under glasshouse conditions in which soil temperature was maintained at 15°C. Treatments consisted of a factorial arrangement of 8 barley cultivars, 2 mycorrhiza (inoculated and non-inoculated), and 3 rates of P (0, 10 and 20 mg kg-1). P utilization efficiency (dry matter yield per unit of P taken up) and agronomic P efficiency among the barley cultivars was significantly negatively correlated with mycorrhizal responses. However, the response to mycorrhizal infection was positively correlated with response to P application. Poor correlation was observed between P concentration when neither mycorrhiza nor P were supplied and the percentage of root length infected. The extent of mycorrhizal infection among the barley cultivars in soil without P amendment varied from 8.6 to 28.6%. Significant interactions between cultivar and P addition, and between mycorrhiza and P addition were observed for shoot dry weight but not root dry weight.
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    Genotypic differences in phosphorus efficiency of wheat (1993)
    Springer
    Plant and soil 155-156 (1993), S. 293-296 
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    ISSN: 1573-5036
    Keywords: efficiency ; genotypic differences ; phosphorus ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In an attempt to evaluate whether breeding and selection for high yielding capacity did change the P requirements of modern wheat cultivars, the response of two wheat cultivars to different levels of P supply was investigated. A traditional cultivar ("Peragis") and a modern cultivar ("Cosir") were cultivated in a C-loess low in available P and high in CaCO3 in 120 cm high PVC pots. Shoot and root growth at different developmental stages was compared. The grain yield of the modern cultivar Cosir was higher at limiting and non-limiting P supply and, therefore, this cultivar can be considered as more P-efficient than the traditional cultivar. From the results it can be concluded that the main factors contributing to the higher P efficiency of the modern cultivar are (i) efficient use of assimilates for root growth characteristics which enhance P acquisition: smaller root diameter, and longer root hairs, (ii) efficient remobilization of P from vegetative plant organs to the grains, and (iii) lower P requirement for grain yield formation because of lower ear number per plant but higher grain number per ear.
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    Effect of phosphorus fertilization on water stress in Douglas fir seedlings during soil drying (1993)
    Springer
    Plant and soil 150 (1993), S. 33-39 
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    ISSN: 1573-5036
    Keywords: droguth tolerance ; phosphorus ; photosynthesis ; plant nutrition ; plant water relations ; Pseudotsuga menziesii ; stomatal conductance ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A growth chamber experiment was conducted to determine if P fertilization to enhance the P nutrition of otherwise N and P deficient Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings reduces water stress in the seedlings during drought periods. Seedlings were grown in pasteurized mineral soil under well-watered conditions and fertilized periodically with a small amount of nutrient solution containing P at either of three levels: 0, 20, or 50 mg P L-1. By age 6 mo, leaf nutrient analysis indicated that N and P were deficient in control (0 mg P L-1) seedlings. The highest level of P fertilization, which doubled leaf P concentration, did not affect plant biomass, suggesting that N deficiency was limiting growth. When these seedlings were subjected to drought, there was no effect of P fertilization on leaf water potential or osmotic potential. Furthermore, P fertilized seedlings had lower stomatal conductance and net photosynthesis rate. These results indicate that enhanced P nutrition, in the presence of N deficiency, does not reduce water stress in Douglas fir seedlings during drought periods.
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    Accumulation of cadmium and selected elements in flax seed grown on a calcareous soil (1993)
    Springer
    Plant and soil 150 (1993), S. 61-68 
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    ISSN: 1573-5036
    Keywords: calciaquoll ; FeEDDHA ; iron ; Linum usitatissimum L. ; manganese ; phloem mobility ; phosphorus ; post-flowering N stress ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seed of flax (Linum usitatissimum L.) grown on calcareous and neutral soils sometimes accumulates relatively high concentrations of Cd. The influence of a post-flowering application of NH4NO3 (115 mg N kg-1), CdSO4 (1 mg Cd kg-1), FeEDDHA (2 mg Fe kg-1), NaH2PO4 (120 mg P kg-1) and ZnSO4 (8 mg Zn kg-1) on seed accumulation of Cd, Fe, N, Mn, P and Zn by flax grown on a Calciaquoll was studied in two experiments under greenhouse conditions. Seed yields were increased by the N and Zn treatments, and the N×Zn interaction was positive. Zinc deficiency delayed flowering and boll formation by up to 20 days and reduced seed size. In the absence of added Cd, seed accumulated up to 0.33 mg Cd kg-1. This Cd accumulation was reduced by approximately 50 and 17% by added Zn and Fe, respectively, but was little affected by P fertilizer and post-flowering N stress. In the presence of added Cd, seed Cd exceeded 3.3 mg Cd kg-1, and the antagonistic effects of Fe and Zn on seed Cd were absent. Seed N, P, Fe and Zn concentrations were increased on average by 10, 45, 31 and 97% by the N, P, Fe and Zn fertilizer treatments, respectively. FeEDDHA reduced seed Mn concentration by approximately 58%. However, seed Mn concentration was much less than that found in vegetative tissue at flowering. Soil-applied Zn may reduce seed Cd concentration in flax under field conditions, and may increase marketability of flax for food use.
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    Minimizing the effect of mineral nitrogen on biological nitrogen fixation in common bean by increasing nutrient levels (1993)
    Springer
    Plant and soil 152 (1993), S. 131-138 
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    ISSN: 1573-5036
    Keywords: bean ; 15N isotope ; nitrogen fixation ; N fertilizer ; phosphorus ; potassium ; Rhizobium tropici ; sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although common bean (Phaseolus vulgaris L.) has good potential for N2 fixation, some additional N provided through fertilizer usually is required for a maximum yield. In this study the suppressive effect of N on nodulation and N2 fixation was evaluated in an unfertile soil under greenhouse conditions with different levels of soil fertility (low=no P, K and S additions; medium = 50, 63 and 10 mg kg−1 soil and high = 200, 256 and 40 mg kg−1 soil, respectively) and combined with 5, 15, 60 and 120 mg N kg−1 soil of 15N-labelled urea. The overall average nodule number and weight increased under high fertility levels. At low N applications, nitrogen had a synergistic effect on N2 fixation, by stimulating nodule formation, nitrogenase activity and plant growth. At high fertility and at the highest N rate (120 mg kg−1 soil), the stimulatory effect of N fertilizer on N2 fixation was still observed, increasing the amounts of N2 fixed from 88 up to 375 mg N plant−1. These results indicate that a suitable balance of soil nutrients is essential to obtain high N2 fixation rates and yield in common beans.
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    Phosphorus fractions in soil solution: Influence of soil acidity and fertiliser additions (1993)
    Springer
    Plant and soil 148 (1993), S. 175-183 
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    ISSN: 1573-5036
    Keywords: carbon ; fertiliser ; fractionation ; pH ; phosphorus ; soil ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of soil acidity and phosphorus fertilization on phosphorus fractions and dissolved organic carbon (DOC) in soil solution was quantified experimentally in an iron humus podzol. Soil solution was isolated by centrifugation from top- and sub-soil samples. Total dissolved phosphorus (TDP), dissolved reactive phosphorus (DRP), dissolved organic phosphorus (DOP) and DOC increased as soil pH and P status increased. DOP was the fraction present at the highest concentration (0.080–0.464 mg P L−1) for the majority of samples. DOC and DOP concentrations which remained relatively constant down the soil profile were also highly correlated. Soluble organic P compounds may make a significant contribution to plant available soil P particularly for soils with low fertility levels. The relatively high DOP concentrations (ca 0.227 mg P L−1) found throughout the soil profile have important consequences with regards to P leaching and plant nutrition.
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    The relative importance of biological and chemical processes in the release of phosphorus from a highly organic sediment (1993)
    Springer
    Hydrobiologia 253 (1993), S. 141-150 
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    ISSN: 1573-5117
    Keywords: sediment ; phosphorus ; release ; anaerobiosis ; bacteria ; pH ; dystrophic lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les bactéries peuvent jouer un rôle considérable dans le relargage anaérobiques du phosphore, soit en catalysant la réduction des hydroxydes de fer, soit comme source directe d'orthophosphates. On a étudié leur importance dans la libération de phosphore à partir des sédiments d'un lac du bouclier canadien, très riches en matière organique. Le relargage de phosphore et de fer a été mesuré en condition aérobique et anaérobique, avec ou sans stérilisation, et à différents pH. On a également mesuré l'évolution du nombre et de l'activité des bactéries dans les sédiments. Le relargage de P après stérilisation peut être expliqué par la lyse cellulaire. Comparativement à la stérilisation, les changements dans la concentration en oxygène ou l'acidification ont peu ou pas d'effet sur le relargage du P. Les mouvements du fer et du phosphore se produisent indépendament à partir de ces sédiments. La plus grande partie du fer total dissous semble lié aux acides humiques, ce qui n'est pas le cas du phosphore.
    Notes: Abstract Bacteria can play an important role in the process of anaerobic phosphorus release: they can act as a direct source of orthophosphates, or as a catalyst of iron hydroxyde reduction. We studied their influence on phosphorus release from highly organic sediments of a Canadian shield lake. Phosphorus and iron release were measured under aerobic and anaerobic conditions, with or without sterilization, and at different pH. We measured also the abundance and activity of bacteria in sediments. The increased P release after sterilization can be explained by cell lysis. Compared to sterilization, changing oxygen concentrations or acidification had little or no effect on P release. In these sediments, phosphorus and iron movements were independent. Most of the total dissolved iron seemed to be linked to humic acids, but not phosphorus.
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    Iron content of sediment and phosphate adsorption properties (1993)
    Springer
    Hydrobiologia 253 (1993), S. 311-317 
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    ISSN: 1573-5117
    Keywords: phosphorus ; sediment ; iron ; aluminum ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphorus can occur in sediments in different forms and accordingly its availability varies. The distinction between the phosphorus fractions is made with two chemical extraction methods; an ammonium oxalate-oxalic acid extraction and an extraction according to Hieltjes & Lijklema (1980). The iron and aluminum liberated with the ammonium oxalate-oxalic acid extraction method is linearly correlated (r 2 = 0.73) with the phosphorus liberated in the first two steps of the Hieltjes and Lijklema extraction by: P = 0.035 (Fe + Al) + 0.001 (P, Fe and Al in mmol g−1). The iron and aluminum (hydr)oxides are very important fractions in the sediment adsorption capacity for phosphorus. The phosphorus sorption capacity (PSC) is 0.080 mol P (mol (Fe + Al))−1 and the adsorption constant (k) is 11.9 µmol P l−1. Here it is assumed that iron and aluminum (hydr)oxide have the same affinity for phosphorus.
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    A comparison of sedimentary and diatom-inferred phosphorus profiles: implications for defining pre-disturbance nutrient conditions (1993)
    Springer
    Hydrobiologia 253 (1993), S. 357-366 
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    ISSN: 1573-5117
    Keywords: weighted averaging ; calibration ; phosphorus ; diatoms ; palaeolimnology ; Northern Ireland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interpreting sedimentary phosphorus profiles in terms of changes in the historical P load is difficult due to variable retention and post-depositional diagenesis. An alternative approach is to use diatom assemblages in surface sediments and derive a transfer function for epilimnetic SRP and total P concentrations using weighted average regression and calibration. The obtained relationship can then be applied to down-core changes in sedimentary diatom assemblages and diatom-inferred P (DI-P) used to assess historical changes in epilimnetic P-concentrations. A diatom-phosphorus calibration data set for 43 eutrophic lakes in Northern Ireland has been constructed and applied to two small eutrophic lakes (Lough Mann, White Lough). DI-total P (i.e. predicted) is highly correlated with observed TP (r 2 = 0.75) for the surface-sediment training data-set. The resultant changes in DI-P derived from application of the transfer function to down-core changes in diatom assemblages are compared to sedimentary P concentrations. The latter are highly variable, presumably due to redox-derived effects, while DI-P profiles are more readily interpretable, and agree with other stratigraphic records of lake eutrophication. The method offers a good possibility of defining pre-disturbance (i.e. natural) phosphorus concentrations in lakes with associated implications for lake-restoration programmes.
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    Detritus and nutrient dynamics in the shore zone of lakes: a review (1993)
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    Hydrobiologia 251 (1993), S. 49-58 
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    ISSN: 1573-5117
    Keywords: lake littoral ; detritus ; macrophytes ; decomposition ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of detritus varies greatly among shore zones of lakes, but in a large majority of these regions detrital pathways prevail. Aside from a great spatial and seasonal variability, macrophytes and bottom sediments appear to be dominant stores of nutrients in these habitats. Macrophytes hold a central position in nutrient cycling in the shore-littoral lake zones. They are the main source of autochthonous detritus as they prevail in the total biomass of littoral organisms, and they are only rarely available as direct food of consumers. Various processes and interactions determine the role of macrophytes in nutrients dynamics. These are: the intensity of nutrient uptake and translocation, release of nutrients by healthy plants and from decomposing plants, exchange of elements between macrophytes and their periphyton, as well as interception of seston by macrophyte stands. Particular plant species differ in their time of dying and susceptibility to decomposition. The changes in decomposing material (size structure of particles and nutrient content) mean that detritus in various stages of decomposition differs in its role in trophic dynamics of shore-littoral lake zones. Several types of shore regions as regards detritus sources and retention level are discussed.
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    Frost formation in the ecotonal zone and its role for release of nutrients (1993)
    Springer
    Hydrobiologia 251 (1993), S. 65-72 
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    ISSN: 1573-5117
    Keywords: Frozen littoral ; frost heave ; nutrient release ; nitrogen ; phosphorus ; calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In winter, the littoral substrate of ecotonal zones along north Swedish rivers and lakes freezes. Even if the littoral is flooded at freeze-up, the ice freezes solid to the shore substrate due to low temperature combined with a gradual decrease in water level during winter. Frost conditions were studied during an 8-year period along eight littoral transects in the River Vindelälven and adjacent riverside lagoons. Heavy frost heave with formation of needle ice was observed in several places. Nutrient release was suggested to take place due to the frost process. Sediment was taken to a laboratory experiment where samples with sediment and water were kept under unfrozen and frozen conditions during six months. N (total-N) and Ca were significantly released to the water, while P (total-P) did not show any clear movement from the frozen sediment. The results indicate that frost processes in ecotonal zones are involved in the movement of nutrients between sediment and water.
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    Extracellular phosphatase activity in sediments of the Breitenbach, a Central European mountain stream (1993)
    Springer
    Hydrobiologia 253 (1993), S. 207-216 
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    ISSN: 1573-5117
    Keywords: stream ; sandy sediment ; phosphorus ; extracellular enzymes ; phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Activity of extracellular phosphatases (phosphomonoesterases) was measured in sandy streambed sediments of the Breitenbach, a small unpolluted upland stream in Central Germany. Fluorigenic 4-methylumbelliferyl phosphate served as a model substrate. Experiments were conducted using sediment cores in a laboratory simulation of diffuse groundwater discharge through the stream bed, a natural process occurring in the Breitenbach as well as many other streams. Streambed sediments contained high levels of particulate phosphorus, but concentrations of dissolved phosphorus in the interstitial water were 3 to 4 orders of magnitude lower. These interstitial concentrations were similar to those in the stream and groundwater. Extracellular phosphatase activity was high in the streambed sediments. These enzymes probably contribute significantly to the flux of phosphorus in sediment by hydrolyzing phosphomonoesters, making free phosphate available to the sediment microorganisms. Factors influencing the kinetic parameters V max (maximum activity) and apparent K m (enzyme affinity) of phosphatase were discharge rates of water through the sediment, water quality (ground- or stream water), and substrate (phosphomonoesters) as well as dissolved ortho-phosphate concentrations. Enzymes are supposed to be effective at limiting substrate concentrations, where, in this study, changes in discharge rates had little influence on rates of hydrolysis. Higher V max and lower K m values were found during percolation of groundwater through the sediment cores, compared with stream water. This indicates that rates of hydrolysis were higher with groundwater, both at substrate limitation and at substrate saturation. This was probably a consequence of the lower levels of dissolved ortho-phosphate in the groundwater.
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    The effect of deposition of organic matter on phosphorus dynamics in experimental marine sediment systems (1993)
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    Hydrobiologia 253 (1993), S. 83-98 
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    ISSN: 1573-5117
    Keywords: organic matter ; phosphorus ; sandy marine sediment ; macrofauna ; boxcosms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of deposition of organic matter on phosphorus dynamics in sandy marine sediments was evaluated using an experimental system (boxcosms) and three different strategies: (1) no supply (2) one single addition (3) weekly additions of a suspension of algal cells (Phaeocystis spec.). Macrofauna (3 species, 6 individuals of each) were added to half of the boxes. Both in the case of the single and weekly additions a clear effect of increased organic matter loading on phosphorus dynamics was found. Following the organic matter addition, porewater phosphate concentrations in the upper sediment layer increased, phosphate release rates from the sediment increased by a factor 3–5 and in the boxes to which a single addition was applied NaOH-extractable phosphorus increased substantially. The increase in phosphate release rates from the sediment was attributed to mineralization of the added material and to direct release from the algal cells. No clear effect of the presence of macrofauna on sediment-water exchange of phosphate could be discovered. The macrofauna were very effective at reworking the sediment, however, as illustrated by the organic carbon profiles. It is hypothesized that the sediment-water exchange rates of phosphate were regulated by the layer of algal material which was present on the sediment surface in the fed boxes. In the boxes to which the single addition was applied porewater phosphate concentrations were lower and NaOH-extractable phosphorus was higher in the presence of macrofauna, suggesting that macrofauna can stimulate phosphate binding in the sediment.
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    The role of microorganisms in mobilization and fixation of phosphorus in sediments (1993)
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    Hydrobiologia 253 (1993), S. 103-121 
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    ISSN: 1573-5117
    Keywords: bacteria ; phosphorus ; phosphorus cycling in lakes ; sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cycling of phosphorus (P) at the sediment/water interface is generally considered to be an abiotic process. Sediment bacteria are assumed to play only an indirect role by accelerating the transfer of electron from electron donors to electron acceptors, thus providing the necessary conditions for redox-and pH-dependent, abiotic sorption/desorption or precipitation/dissolution reactions. Results summarized in this review suggest that (1) in eutrophic lakes, sediment bacteria contain as much P as settles with organic detritus during one year (2) in oligotrophic lakes, P incorporated in benthic bacterial biomass may exceed the yearly deposition of bioavailable P several times (3) storage and release of P by sediment bacteria are redox-dependent processes (4) an appreciable amount of P buried in the sediment is associated with the organic fraction (5) sediment bacteria not only regenerate PO4, they also contribute to the production of refractory, organic P compounds, and (6) in oligotrophic lakes, a larger fraction of the P settled with organic detritus is converted to refractory organic compounds by benthic microorganisms than in eutrophic lakes. From this we conclude that benthic bacteria do more than just mineralize organic P compounds. Especially in oligotrophic lakes, they also may regulate the flux of P across the sediment/water interface and contribute to its terminal burial by the production of refractory organic P compounds.
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    Sedimentation of phosphorus in limnetic and estuarine environments in the River Öre system, northern Sweden (1993)
    Springer
    Hydrobiologia 253 (1993), S. 233-248 
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    ISSN: 1573-5117
    Keywords: phosphorus ; iron ; organic carbon ; sedimentation ; estuary ; lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sedimentation of phosphorus was studied during the spring flood in April and May 1991 in Lake Örträsket and the Öre Estuary, northern Sweden. Lake Örträsket has an area of 7.3 km2 and a mean depth of 22 m and is located 100 km from the coast halfways along the course of the River Öre. The river ends in a semi-closed low salinity estuary with an area of ca. 50 km2 and a mean depth of 16 m. Sedimentation of phosphorus, iron and organic carbon were measured with sediment traps in Lake Örträsket and in the Öre Estuary. Characterization of particulate phosphorus in river water, sediment trap material and sediments were performed by the sequential extraction procedure proposed by Hieltjes & Lijklema (1980). Apart from being an efficient trap for suspended particles including particulate phosphorus, Lake Örträsket was shown to serve as a source for particulate material during spring 1991. The Öre Estuary, on the other hand, constitutes an efficient trap for the total supply of river-borne phosphorus during the spring flood period. Phosphorus was shown to be closely related to iron in particulate material in both the lake and the estuary. Adsorption of phosphorus on settling inorganic particles seems to be an important process, which is particularly pronounced in the estuary.
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    Sulfate control of phosphorus availability in lakes (1993)
    Springer
    Hydrobiologia 253 (1993), S. 275-280 
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    ISSN: 1573-5117
    Keywords: phosphorus ; iron ; sulfate ; lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During summer stratification large amounts of phosphorus (P) accumulate in anoxic bottom waters of many lakes due to release of P from underlying sediments. The availability to phytoplankton of this P is inversely related to the Fe:P ratio in bottom waters. Using data from 51 lakes, we tested the hypothesis that sulfate concentration in lake water may be critical in controlling the Fe:P ratio in anoxic bottom waters. Results showed that Fe:P ratios in bottom waters of lakes were significantly (p〈0.001) related to surface water sulfate concentrations. The higher Fe:P ratios in low sulfate systems is due not only to higher iron concentrations in anoxic bottom waters but also to lower P concentrations in anoxic waters. Thus, our results suggest that anthropogenically induced increases in sulfate concentrations of waters (e.g. from fossil fuel burning) may have a double effect on P cycling in lakes. Higher sulfate concentrations can both increase the magnitude of P release from sediments as well as increase the availability of P released from sediments into anoxic bottom waters.
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    Eight years of internal phosphorus loading and changes in the sediment phosphorus profile of Lake Søbygaard, Denmark (1993)
    Springer
    Hydrobiologia 253 (1993), S. 345-356 
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    ISSN: 1573-5117
    Keywords: phosphorus ; retention ; sediment ; release ; fractionation ; iron:phosphorus ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During each of the first 8 years following an 80–90% reduction in external phosphorus loading of shallow, hypertrophic Lake Søbygaard, Denmark in 1982, phosphorus retention was found to be negative. Phosphorus release mainly occurred from April to October, net retention being close to zero during winter. Net internal phosphorus loading was 8 g P m−2 y−1 in 1983 and slowly decreased to 2 g P m−2 y−1 in 1990, mainly because of decreasing sediment phosphorus release during late summer and autumn. The high net release of phosphorus from Lake Søbygaard sediment is attributable to a very high phosphorus concentration and to a high transport rate in the sediment caused by bioturbation and gas ebullition. Sediment phosphorus concentration mainly decreased at a depth of 5 to 20 cm, involving sediment layers down to 23 cm. Maximum sediment phosphorus concentration, which was 11.3 mg P g−1 dw at a depth of 14–16 cm in 1985, decreased to 8.6 mg P g−1 dw at a depth of 16–18 cm in 1991. Phosphorus fractionation revealed that phosphorus release was accompanied by a decrease in NH4Cl-P + NaOH-P and organic phosphorus fractions. HCl-P increased at all sediment depths. The Fe:P ratio in the superficial layer stabilized at approximately 10. Net phosphorus release can be expected to continue for another decade at the present release rate, before an Fe:P ratio of 10 will be reached in the sediment layers from which phosphorus is now being released.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00050760
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  • 95
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    Release rates and biological availability of phosphorus released from sediments receiving aquaculture wastes (1993)
    Springer
    Hydrobiologia 253 (1993), S. 367-372 
    Details
    ISSN: 1573-5117
    Keywords: algae ; aquaculture ; phosphorus ; sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aquaculture is an increasingly significant user of freshwater resources in Scotland. In 1989, the total fish biomass produced in Scottish freshwater amounted to 7000 t. 50% of this total was reared in floating cage systems situated in lochs (lakes). Both solid (mainly in the form of uneaten feeds and faecal matter) and dissolved byproducts of the production cycle enter the limnetic environment untreated. Much solid waste material accumulates directly on the sediments beneath the cage systems. This leads to a localised enrichment in nutrient elements of the sedimentary environment. The experiments served to quantify rates of total phosphorus (TP) and dissolved reactive phosphorus (DRP) release from undercage and control sites, and to relate such releases to the biological availability of the released P. Results indicate significantly higher levels of NH4Cl-extractable P in sediments affected by waste deposition from fish cages. TP and DRP release, and greater growth of Chla are obtained from undercage cores compared with control sites. No link between extractable-P content of sediments, or release rate and Chla production was established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00050762
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  • 96
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    Transport and retention of matter in riparian ecotones (1993)
    Springer
    Hydrobiologia 251 (1993), S. 95-101 
    Details
    ISSN: 1573-5117
    Keywords: Land/stream ecotones ; bank runoff ; aerial drift ; retention ; carbon ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ‘stream’ ecosystem is described as a three-layered system, vertically as well as horizontally. The land/stream ecotone is defined as the area where lotic and edaphic characters overlap at the time of observation. The study site — ‘Oberer Seebach’, near the Biological Station Lunz — and the methods employed are described. Only a surprisingly small fraction (less than 10 %) of total imports is transported across the surface ecotones. The driving variables determining bank runoff and aerial drift are described and discussed. The importance of channel areas which are periodically flooded is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007169
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  • 97
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    The trophic history of Enäjärvi, SW Finland, with special reference to its restoration problems (1993)
    Springer
    Hydrobiologia 268 (1993), S. 147-162 
    Details
    ISSN: 1573-5117
    Keywords: eutrophication ; sediments ; palaeolimnology ; phosphorus ; diatoms ; chironomids ; lake restoration ; Finland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The eutrophicated Enäjärvi was studied by paleolimnological analyses and sediment mapping. The sedimentary record indicates that the lake nutrient balance had deteriorated due to lowering of the lake water level in the year 1928. From that event onwards Chironomus plumosus and Cyclotella astraea characterize the chironomid and diatom communities. The concentrations of sedimentary total and mobile phosphorus show that since then the internal load of phosphorus has controlled the nutrient cycle of the lake. The areal distribution of mobile phosphorus can be explained by dominant wind directions and wind resuspension of the sediment is the key factor in the nutrient cycle. Restoration of Enäjärvi must be based on actions which stabilize the surface sediment and improve its natural phosphorus-binding capacity. They include the regulation of lake water to as high a level as possible and the removal of the majority of roach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014050
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  • 98
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    Influence of nitrogen and phosphorus fertilizers on amount and nutrient content of litterfall in a regrowth eucalypt forest (1993)
    Springer
    New forests 7 (1993), S. 33-47 
    Details
    ISSN: 1573-5095
    Keywords: eucalypt ; regrowth forest ; litter ; litterfall ; fertilizer ; nitrogen ; nutrient cycling ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of fertilizer treatment on nutrient transfers to the forest floor were examined in regrowth Eucalyptus diversicolor F. Muell. forest. Dry weight and nutrient content of leaf litterfall and total litterfall were measured for 3 years in a stand to which two levels of N (0, 200 kg ha-1 year-1) were applied each year at each of three levels of a single initial application of P (0, 30, 200 kg ha-1). Annual accessions of litter to the forest floor were significantly increased by additions of both N (by 17%, 18% and 21% in the 3 years) and 200 kg P ha-1 (by 8%, 8% and 4% in the 3 years) but there was no interaction between effects of N and P treatments. Fertilizer application also had a significant effect on the nutrient content of leaf litterfall and total litterfall. Concentration of N in leaf litterfall was 9% to 23% greater on plots treated with N fertilizer compared to untreated plots. The amounts of N in litterfall were about 30% greater on N-treated compared to untreated plots. On plots treated with 200 kg P ha-1, P concentrations in leaf litter were 50% to 100% greater than in litter from plots receiving no P. Application of 200 kg P ha-1 increased the amounts of P in annual litterfall by 32% to 87%. The greatest increase in P accessions occurred soon after fertilizer treatment. The amounts of Ca, K, and Na in litterfall were also significantly increased by fertilizer application. For Ca and K this was due partly to increases in element concentrations in litterfall following application of treatments. The effect of fertilizers on internal recycling of plant nutrients and on litter accumulation and nutrient dynamics in forest floor litter is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037470
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  • 99
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    Transport of groundwater-borne phosphorus to Lake Bysjön, South Sweden (1993)
    Springer
    Hydrobiologia 251 (1993), S. 211-216 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus ; ecotone ; groundwater ; lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lake Bysjön is a hypertrophic seepage lake, with groundwater as a main external source of phosphorus. Twelve groundwater samples from the vicinity of the lake were high in phosphate (0.4 to 11 mg l−1, mean value 2.57 mg l−1 PO4-P), both within the riparian zone and in two shallow wells located upstreams the lake in the nearby village. Phosphorus sorption capacity of four sand samples measured with the Langmuir isotherm method was low (7.3 to 121,1 mg kg−1 PO4-P), with the lowest values found within the riparian zone. It is suggested that the phosphorus originates from garden fertilizers and other human sources, and that the low absorption capacity of the soils is caused by the leaching of calcium from the watershed, a process which started some 3000 years ago. Riparian zone itself has almost no retention capacity, and processes within it (e.g., redox-related) have only secondary importance for the transport of phosphorus to the lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007180
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  • 100
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    The effect of herbivorous crustacean zooplankton on epilimnetic carbon and phosphorus cycling (1993)
    Springer
    Hydrobiologia 254 (1993), S. 21-34 
    Details
    ISSN: 1573-5117
    Keywords: biomanipulation ; microcosms ; carbon cycle ; phosphorus ; primary production ; sedimentation ; plankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plastic limnocorrals (LCs; volume 70 m3) in oligo-mesotrophic Lake Lucerne, Switzerland were used to manipulate planktonic communities by (1) removing large zooplankton at the start of the experiment, and (2) adding phosphate during experiments of two weeks duration. Primary production (14C-assimilation), chlorophyll, standing crops and sedimentation of particulate organic carbon (POC) and of particulate phosphorus, as well as plankton composition were assessed simultaneously in two to four differently treated LCs. Carbon and phosphorus mass balances were calculated from assimilation, temporal change in standing crop of particulate matter, and sedimentation. A quick elimination of crustaceans by screening hardly increased primary production, but decreased sedimentation and mineralisation of particulate organic carbon, and thus significantly enhanced the standing crop of POC, but decreased POC turnover. The exclusion of crustaceans increased the mean residence time of total phosphorus by a reduced P loss by sedimentation. Increased grazing pressure during the experiment showed little grazing induced effect on plankton composition and primary production except at the very end. We conclude that in an oligo-mesotrophic lake, buffering mechanisms attenuate the impact of changing grazing pressures on primary production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007762
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