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  • nitrogen  (54)
  • Rat  (48)
  • Nicotiana
  • phosphorus
  • Springer  (171)
  • Blackwell Publishing Ltd
  • National Academy of Sciences
  • 1990-1994  (102)
  • 1980-1984  (69)
  • 1925-1929
  • 1992  (102)
  • 1980  (69)
Collection
Keywords
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  • Springer  (171)
  • Blackwell Publishing Ltd
  • National Academy of Sciences
  • Wiley-Blackwell  (2)
Years
  • 1990-1994  (102)
  • 1980-1984  (69)
  • 1925-1929
Year
  • 1
    Electronic Resource
    Electronic Resource
    Diet-switching by gypsy moth: effects of diet nitrogen history vs. switching on growth, consumption, and food utilization (1992)
    Springer
    Entomologia experimentalis et applicata 64 (1992), S. 225-238 
    Details
    ISSN: 1570-7458
    Keywords: Lymantria dispar (L.) ; diet switching ; nitrogen ; specialization ; plant-animal interactions ; insect behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gypsy moth (Lymantria dispar (L.) (Lepidoptera: Lymantriidae)) larvae were reared from hatch on 1.25% N or 3.5% N artificial diet (previous diet) and switched reciprocally to the other diet (current diet) after molting into the second, third, fourth, or fifth instar. The nitrogen concentration of food consumed during previous instars had a strong residual effect on the growth rate in subsequent instars when a diet switch was made during instars two through four, but did not affect growth rate of fifth-instar larvae despite effects on food consumption and utilization. In early instars, larvae reared on 1.25% N artificial diet and then switched to 3.75% N diet had lower mass-adjusted growth rates than larvae continuously reared on 3.75% N diet. Conversely, larvae reared on 3.75% N diet and switched to 1.25% N had higher mass-adjusted growth rates than larvae reared continuously on 1.25% N diet. Relative to larvae previously reared on 1.25% N diet, fifth-instar male larvae previously reared on 3.75% N diet had slightly lower consumption rates, higher net growth efficiency (ECD), and higher gross growth efficiency (ECI). Larvae previously reared on 3.75% N diet tended to have lower food assimilation efficiency (AD) and lower nitrogen assimilation efficiency (AD(N)). Although both previous and current diet nitrogen concentration strongly affected larval growth and food utilization, the interaction term between these was not significant for any response variables except ECD and ECI. Because the interaction term reflects the effect of switching per se, the results indicate that there was a metabolic cost associated with switching, but no inherent net cost or benefit of diet-switching to growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341086
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  • 2
    Electronic Resource
    Electronic Resource
    On the rate-determining step and the role of potassium in the catalytic synthesis of ammonia (1992)
    Springer
    Catalysis letters 13 (1992), S. 45-53 
    Details
    ISSN: 1572-879X
    Keywords: Ammonia ; synthesis ; nitrogen ; rate-determining step ; potassium promotion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The simple concept of a single rate-determining step, the dissociation of N2(a), in ammonia synthesis is inconsistent with experimental results. It is proposed that three reaction steps, N2(a) → 2N(a) (1) N(a) + H(a)→NH(a) (2) NH3(a)→NH3(g) (3) are dominant in determining the rate of synthesis. Under industrial conditions reactions (2) and (3) are more important than (1). The role of K+ as promoter in these reactions is discussed, especially as an “anchor” for adsorbed oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00770946
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  • 3
    Electronic Resource
    Electronic Resource
    A study of nitrogen and carbon dioxide chemisorption on platinum black (1992)
    Springer
    Catalysis letters 16 (1992), S. 159-164 
    Details
    ISSN: 1572-879X
    Keywords: Chemisorption ; nitrogen ; carbon dioxide ; platinum ; water gas shift reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relationship between sites responsible for nitrogen chemisorption and sites responsible for stronger adsorption of carbon dioxide on platinum black is reported. A 2 to 1 ratio has been found between molecules of more strongly adsorbed carbon dioxide and molecules of nitrogen chemisorbed on individual samples. This relationship has allowed us to deduce the structure of chemisorbed carbon dioxide. Carbon dioxide is relatively weakly chemisorbed on platinum. Reasons for the weakness of this chemisorption are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00764366
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  • 4
    Electronic Resource
    Electronic Resource
    Measurement of total dissolved phosphorus in small volumes of iron rich interstitial water (1992)
    Springer
    Aquatic sciences 54 (1992), S. 1-9 
    Details
    ISSN: 1420-9055
    Keywords: Sediment ; interstitial water ; phosphorus ; iron ; persulfate digestion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is shown that sorption of orthophosphate to iron compounds, formed during persulfate digestion, can cause a significant underestimation of total dissolved phosphorus in interstitial waters rich in iron and poor in phosphorus. Labelling the samples with carrier free32PO4 before digestion allows to correct for these losses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877261
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  • 5
    Electronic Resource
    Electronic Resource
    The influence of nutritional and genetic factors on larval performance of the cinnabar moth, Tyria jacobaeae (1992)
    Springer
    Entomologia experimentalis et applicata 62 (1992), S. 29-36 
    Details
    ISSN: 1570-7458
    Keywords: Alkaloids ; cinnabar moth ; insect genetics ; larval performance ; Lepidoptera ; nutritional ecology ; nitrogen ; sugar ; Tyria jacobaeae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a laboratory experiment using full-sibs, 60% of the variation in pupal weight of the monophage Tyria jacobaeae L. (Lepidoptera, Arctiidae) could be explained by variation in the nitrogen concentration of the food plant, Senecio jacobaea L. and only 4% by variation in sugar concentration. Larval weight and growth rates of young and old larvae were also positively correlated with nitrogen and sugar concentration. Developmental time was negatively correlated with nitrogen concentration. In a second experiment full-sib families differed significantly in larval weight at day 7, mortality, growth rate and developmental time. Pupal weight did not differ significantly among families, but was positively correlated with nitrogen concentration of Senecio. Larval performance was not significantly influenced by concentrations of sugars or alkaloids. We conclude that larval performance of Tyria during most of the larval period is mainly determined by genetic factors, but pupal weights are primarily determined by nitrogen concentration of the food plant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185638
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  • 6
    Electronic Resource
    Electronic Resource
    Verapamil induces increased bone volume and osteopenia in female rats but has the opposite effect in male rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 524-526 
    Details
    ISSN: 1432-0827
    Keywords: Verapamil ; Bone ; Osteopenia ; Rat ; Female ; Intestinal calcium absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Verapamil inhibits the intestinal absorption of calcium (Ca) and increases serum parathyroid hormone in rats. The effects of verapamil on bone tissue after long-term treatment is, however, not well described. Adult female and male Sprague-Dawley rats received verapamil in their drinking water at a dosage of 0.075 mg/ml (low dose) or 0.75 mg/ml (high dose) for 12 weeks; control rats received only drinking water. All rats were fed a diet containing 0.1% Ca and 0.5% P. In female rats, the amount of bone ash per volume was significantly reduced from 0.742 g/ml in controls to 0.713 g/ml after low-dose treatment of verapamil, and to 0.667 g/ml following high-dose treatment (P〈0.01). The tibial length was increased from 39.7 mm in controls to 40.3 mm or to 40.7 mm after low or high doses (P〈0.01). The tibial volume increased from 0.385 ml in controls to 0.397 ml after low doses and to 0.429 ml after high doses (P〈0.01). In contrast, in male rats the amount of bone ash per volume was significantly increased from 0.578 g/ml in controls to 0.580 g/ml after low doses and to 0.620 g/ml after high doses of verapamil (P〈0.01). The tibial bone volume in males as decreased from 0.633 ml in controls to 0.641 ml after low doses and to 0.583 ml after high doses (P〈0.05). The tibial length in the males was not changed by verapamil. The intestinal absorption of Ca was reduced in male rats from 5.28 in controls to 4.03 (serosa/mucosa) after low-dose treatment and to 2.46 after high-dose treatment with verapamil (P〈0.05). In female rats, the intestinal absorption of Ca did not change after verapamil treatment. Thus, chronic treatment with verapamil in female rats induced osteopenia whereas in male rats bone growth was inhibited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582167
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  • 7
    Electronic Resource
    Electronic Resource
    Bone blood flow and In vitro proliferation of bone marrow and trabecular bone osteoblast-like cells in ovariectomized rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 336-341 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Osteoblast-like culture ; Ovariectomy ; Estrogens ; Bone blood supply
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Ovariectomy in the rat induces a rapid osteopenia associated with an elevated bone turnover. One hundred and twenty-day-old rats were ovariectomized (OVX) or sham-operated (n=6–8 per group and per time period studied). 45Ca accretion rate and bone blood flow (microspheres trapping technique) in the femurs were determined at 28, 42, 84, and 119 days after ovariectomy. Both parameters were markedly increased by 84 days and subsided thereafter. At the 42nd day, when bone turnover was maximal, bone marrow and trabecular bone cultures were obtained from shamoperated and ovariectomized animals (n=10/group). Proliferation rate of bone marrow cells and trabecular osteoblast-like cells estimated by fibroblast colony-forming units (FCFU) efficiency and cell counting was markedly increased in primary and secondary cultures in ovariectomy. These data fitted well with the enhanced number of osteoblasts observed in situ in the long bone metaphyses of estrogen-depleted animals. As estrogens were shown in the literature to inhibit proliferation of the red cell line and of other hemopoietic lines, it is possible that estrogens, through a general mechanism, inhibit hemopoietic and stromal lines and also the proliferation of bone marrow-derived trabecular bone cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301631
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  • 8
    Electronic Resource
    Electronic Resource
    The influence of tactile stimulation of nipples on the milk ejection reflex in the rat (1992)
    Springer
    Journal of comparative physiology 170 (1992), S. 645-650 
    Details
    ISSN: 1432-1351
    Keywords: Milk ejection reflex ; Positive pressure oscillations ; Motor activity of pups ; Tactile stimulation of nipples ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes of positive pressure exerted by pups on nipples during sucking were investigated using anesthetized, lactating dams. It was found that, every 50–60 s, individual pups performed bouts of pressure oscillations (3/s) of high amplitude which lasted about 10–12 s and coincided with periods of increased motor activity. During the intervals, when pups were quiet, series of low-amplitude oscillations (3/s) were also observed. Using a strain measuring method to record the activity of sucking pups, synchronization of activity of two or more pups was found to occur periodically every 25–30 s and, most frequently, 10–30 s before the reflex increase of milk pressure. In further experiments, artificial tactile stimulation was applied to the dam's nipples using the joint action of suction and positive pressure. Following a short-term (10–20 s) increase in frequency and amplitude of artificial nipple stimulation, 60%–80% of all reflexive peaks of milk pressure were elicited with a latency of 19 ± 5 s. This suggests that there are specific conditions under which the stimulation of nipples by pups may trigger the formation of the milk ejection reflex in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199340
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  • 9
    Electronic Resource
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    Effects of lesion of the inferior olivary complex by 3-acetylpyridine on learning and memory in the rat (1992)
    Springer
    Journal of comparative physiology 171 (1992), S. 657-664 
    Details
    ISSN: 1432-1351
    Keywords: Inferior olivary complex ; Cerebellum ; 3-acetylpyridine ; Harmaline ; Learning ; Memory ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary DA/HAN-strained male rats (pigmented rats) were submitted to two experimental tasks consisting of spatial learning (water-escape) and a passive avoidance conditioning. Both these tasks were performed by different animals. In order to destroy the inferior olivary complex, the animals were injected with 3-acetylpyridine either 9 days prior to the initial learning session or 24 h after completion of the learning task. They were retested (retrieval test) 10 days after the initial learning was achieved. Learning and retention were compared to those noted in control rats. Administration of 3-acetylpyridine before the initial learning did not prevent the spatial learning but the scores were greatly altered and the number of trials needed to reach the fixed learning criterion was much greater than in controls. However, 10 days later the animals had memorized their initial experience. Injection of 3-acetylpyridine after the initial learning session impaired memory: the animals had completely forgotten their initial learning. It can therefore be concluded that lesion of the afferent climbing fibres to the cerebellar cortex alters learning and retention of a spatial task. Such a lesion does not interfere with learning and retention of a passive avoidance conditioning, since in this condition the experimental animals injected with 3-acetylpyridine either before or after the initial learning behave similarly to controls. The effects of the inferior olivary complex lesion are obviously different according to the task to be learnt, suggesting that these two tasks do not require the integrity of the same nervous structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194113
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  • 10
    Electronic Resource
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    The determination of phosphonate base scale inhibitors in brines by plasma spectrometry (1992)
    Springer
    Microchimica acta 109 (1992), S. 201-209 
    Details
    ISSN: 1436-5073
    Keywords: phosphonate base scale inhibitor ; brine ; direct current plasma ; inductively coupled plasma atomic emission spectrometry ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The determination of phosphonate base scale inhibitors in brines by direct current plasma (DCP) and inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. The first method is based on a direct nebulization of the brine samples and plasma using the phosphorus line at 213.618 nm. The second method involves extraction of phosphorus as phospho-antimonyl molybdate complex into methylisobutyl ketone (MIBK) phase and analysis of the extract for molybdenum using the Mo 313.260 nm line. Comparison between the proposed methods and an established recommended method [1] shows excellent agreement between the results in addition to the sensitivity and ease of automation provided by AES.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242475
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  • 11
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    Fertilizer regime and changes in the phosphate and potash status of a silty marine clay soil during 25 years (1980)
    Springer
    Nutrient cycling in agroecosystems 1 (1980), S. 95-101 
    Details
    ISSN: 1573-0867
    Keywords: soil fertility ; phosphorus ; potassium ; green manure ; crop rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Changes in the soil phosphorus and potassium status on three farming systems in the Northeast Polder during 25 years are related to the fertilizer regime over this period. The changes in the nutrient status of the soil are reflected in fertilizer policy. High rates of phosphate dressings markedly increased the phosphate status of the soil and built up a reserve of phosphate. In contrast, the potassium status decreased by about half, because only potatoes in the rotation were dressed with potassium. Methods of fertilization are discussed and suggestions are made with regard to possible improvements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01073181
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  • 12
    Electronic Resource
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    Effect of foliar sprayings of urea during or after anthesis on dry matter and nitrogen accumulation in the grain of two wheat cultivars ofT. aestivum L. (1992)
    Springer
    Nutrient cycling in agroecosystems 31 (1992), S. 79-84 
    Details
    ISSN: 1573-0867
    Keywords: Wheat ; nitrogen ; grain protein content ; grain filling ; urea spraying
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this work was to determine the effect of foliar urea spraying during or after anthesis, on dry matter and nitrogen accumulation in the wheat grain of two cultivars, differing in grain protein content. The experiment was carried out in the field, and 20 kg N ha−1 as urea (46-0-0) was sprayed at anthesis, 7 or 14 days after anthesis. Dry weight, N content and N percentage of the grain were determined at several stages of its development. Neither the rate nor the duration of dry matter accumulation in the grain was significantly modified by N sprayings at anthesis or later and, consequently, not its final weight. Nitrogen sprayings at anthesis or later increased the grain N content and N percentage at ripeness in both cultivars, but to a greater extent in the low grain protein cultivar. Greater N content in the grain was attributed to a rapid uptake of the N applied and not to a longer duration of the period of N accumulation. The different responses of the cultivars to N sprayings can be related to differences in N demand, and is probably associated, also, to a genetic ability to accumulate N in the grain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01064230
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  • 13
    Electronic Resource
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    Influence of delaying flood and preflood nitrogen application on dry-seeded rice (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 55-59 
    Details
    ISSN: 1573-0867
    Keywords: 15N ; nitrogen ; rice ; soil N ; N fertilizer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the southern U.S. rice belt it is recommended that rice (Oryza sativa L.) grown in the dry-seeded, delayed flood cultural system have the preflood N fertilizer applied and the field flooded at the fourth to fifth leaf stage of plant development. The objective of this field study was to determine if delaying the flood and preflood N application past the fifth leaf stage was detrimental to rice total N and fertilizer15N uptake, total dry matter, and grain yield. This study was conducted on a Crowley silt loam (Typic Albaqualfs) and a Perry clay (Vertic Haplaquepts). The preflood N fertilizer and flood were delayed 0, 7, 14, or 21 d past the fourth to fifth leaf stage, after which time a permanent flood was established and maintained until maturity. All treatments received 20.5 g N m−2 as15N-labeled urea in three topdress applications. All plant and soil samples were taken at maturity. Harvest index increased as the preflood N and flood were delayed past the 4 to 5 leaf stage. Total N in the grain + straw either decreased or showed a decreasing trend as the N and flood were delayed. Similarly, uptake of native soil N decreased as flood was delayed. Conversely, percent recovery of fertilizer N in the rice plant and the plant-soil system increased as the preflood N and flood were delayed. Rice grain yield was not significantly affected by delaying the preflood N and flood up to 21 d.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054394
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  • 14
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    The interpretation of Olsen extractable P values in relation to recommendations for the fertilizer requirements of crops (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 223-227 
    Details
    ISSN: 1573-0867
    Keywords: Soil testing ; phosphorus ; relative yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment, with Okra (Abelmoschus esculentus L.) as the test crop, was conducted on twenty-one soils ranging in Olsen's extractable phosphorus from 1.8 to 15.5µg Pg−1 soil. The experiment was conducted at Punjab Agricultural University, Ludhiana, India. The soils were nonsaline with pH ranging from 7.7 to 8.6. A critical level of 2.55µg Pg−1 soil was predicted by Cate and Nelson's (1971) statistical procedure. Because of a wide range in relative yields, this value did not accurately predict response to applied P. An approach to compute minimum response to applied fertilizer, which is likely to be obtained at a particular Olsen P level, has been presented. It involves calculation of lower 60 percent confidence limits for relative yield and fitting loge-linear regression to the transformed data. The regression was tested on a published data set and was found to hold well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048784
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  • 15
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    Two post thinning fertilizer trials inPinus radiata in New South Wales, Australia (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 259-267 
    Details
    ISSN: 1573-0867
    Keywords: Nitrogen ; phosphorus ; timber increment ; fertilization ; Pinus radiata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two trials inPinus radiata growing on different sites in N.S.W. allowed consideration of fertilizer applications after 2nd or 3rd thinning. The trials included factorial applications of N and P at a single thinning intensity plus a further treatment which allowed assessment of different thinning intensities. The most significant growth responses were obtained by application of N and P in combination. The largest response (additional productivity compared with the unfertilized control) occurred 4 years after application and after 7 years there was no additional absolute response for either of the two sites. The largest fertilizer response was 70 m3 ha−1 over 7 years on one site and 36 m3 ha−1 on the other, indicating differences in absolute responses between sites. It was concluded that in planning treatments the most responsive sites near the end of the rotation should be selected to maximise economic returns. Foliage analyses indicated differences between sites at the commencement of the study. It was concluded that either a single year of foliage analyses at study commencement is of value, or sampling every year of the study should be used to analyse responses, but a single year of analysis during or at the end of the study would not be of value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01050363
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  • 16
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    Nutrient-chlorophyll trajectories across trophic gradients (1992)
    Springer
    Aquatic sciences 54 (1992), S. 58-76 
    Details
    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; nitrogen ; chlorophyll-a ; slope estimator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We estimate the response of chl-a (mg · m−3) to changes in concentrations of total phosphorus (TP) by calculating the slopeS = Δchl-a/ΔTP in chl-a =f(TP) graphs. Results show that in years where algae are P-limited oligotrophic lakes respond less (median slope 0.21) to changes in nutrient concentrations than eutrophic lakes, (median slope 0.31) and these again less than hypereutrophic lakes, (median slope 1.02). We find no saturation value for the slope within the TP range considered (6–480 mg · m−3). Chl-a in eutrophic lakes responds more frequently to non-nutrient factors than oligotrophic and hypereutrophic lakes. Results obtained by replacing TP with a new nutrient parameter, TP′ = 0.056 · TP · IN0.226, in which inorganic nitrogen, IN, is factored in, suggest that nitrogen has an influence on chl-a in oligotrophic lakes. Blue-green algae respond less to changes in TP than other algal species, e.g., diatoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877264
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  • 17
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    Possibilities and limitations of lake restoration: Conclusions for Lake Lugano (1992)
    Springer
    Aquatic sciences 54 (1992), S. 381-390 
    Details
    ISSN: 1420-9055
    Keywords: Eutrophication ; phosphorus ; lake restoration ; internal restoration measures for lakes ; Swiss lakes ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In most lakes eutrophication is linked to an excessive input of phosphorus. Lake restoration by reduction of P-input (external measure) has led to a considerable drop of the P-concentration in all major Swiss lakes as well as in many other lakes. Internal restoration measures such as artificial mixing, drainage of hypolimnetic water, flushing, aeration, biomanipulation and others serve to improve and accelerate the response of a lake to external measures. For the case of Lago di Lugano, a simple two-box model is employed to demonstrate that a reduction of the P-input to about 25% of the present values is necessary to reach the “P-criterion” (P-concentration below 30 µg/l). Internal measures could possibly accelerate the extremely slow response of the northern basin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878149
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  • 18
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    Fine structure of fetal rat calvarium; provisional identification of preosteoclasts (1980)
    Springer
    Calcified tissue international 31 (1980), S. 21-28 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Calvarium ; Electron microscopy ; Preosteoclasts ; Osteoclasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary This is a study of the fine structure of cells of the 20-day fetal rat calvarium. Special attention is given to identifying and characterizing preosteoclasts. These cells are relatively common and located largely, but not exclusively, at the endocranial bone surface. The preosteoclasts are characterized by abundant mitochondria, an incomplete perinuclear Golgi apparatus, and variable-shaped dense granules. The dense granules are unique in appearance in that they contain an internal dense matrix surrounded by a clear halo. Most granules are circular in shape but some are elongate or tubular in form. Granules with identical appearance are observed in osteoclasts. The preosteoclasts are mononucleate, or occasionally binucleate. It is suggested that because preosteoclasts are morphologically distinctive and relatively abundant, it should be feasible to separate these cells from a heterogeneous cell isolate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02407163
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  • 19
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    Effect of a five-week swimming program on rat bone: A histomorphometric study (1992)
    Springer
    Calcified tissue international 51 (1992), S. 137-142 
    Details
    ISSN: 1432-0827
    Keywords: Swimming exercise ; Bone histomorphometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To specify the exercise-induced changes on different skeletal sites, the effect of a 5-week endurance swin training was studied in rats. Eighteen Lyon strain (Sprague-Dawley) 5-week old female rats were divided into nine sedentary and nine swimming rats. Each swim training session was increased by 15 minutes from 2–6 hours per day. A histomorphometric study was performed at the primary and secondary spongiosa of the distal femur and at the secondary spongiosa of lumbar and thoracic vertebral bodies. After training, bone loss was observed in the secondary spongiosa of lumbar vertebral bodies (24.7%) and in the primary spongiosa of distal femur (15.2%). A tendency to bone loss was also detected in the secondary spongiosa of distal femur (10.8%), whereas no change was detected in thoracic vertebral bodies. In secondary spongiosa, bone loss was accompanied with a thinning of trabeculae. Total eroded surfaces and osteoid surfaces were significantly decreased in the three studied skeletal sites, suggesting a decreased bone turnover. The decreased thickness of osteoid seams in both lumbar vertebrae and distal femur could mean that the osteoblastic activity has also been altered at the cell level, leading to thinning of trabeculae. Five-week swim training with such duration and intensity of exercise appears unable to increase bone volume in rats and, therefore, causes adverse effects. The three studied bones seemed to adapt differently to experimental conditions. The lack of ground reaction forces induced by water immersion might have contributed to the observed bone loss. “Normal” gravity would be an important cofactor in the osteogenic effects of exercise.
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    URL: http://dx.doi.org/10.1007/BF00298502
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    An automatic microspectrophotometric scanning method for the measurement of bone formation rates in vivo (1980)
    Springer
    Calcified tissue international 32 (1980), S. 63-68 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Bone formation ; Fluorochrome ; Microphotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A method for quantitative studies of the formation rate of bone has been developed. After vital staining with calcein, the fluorescence of a bone section was measured with a microphotometer controlled by a mini computer. After staining the bone structure with alizarin red S in a second step, the section was measured in transmitted light. The two data sets were combined and the shortest distances between the bone surface and the fluorescence lines were computed. With this information the distance distribution and the bone area between the label and the surface could be calculated in two different ways: with the single labeling and the continuous labeling techniques. The advantages and disadvantages of the two methods are discussed and compared with those of other techniques.
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    URL: http://dx.doi.org/10.1007/BF02408522
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  • 21
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    A quantitative histologic analysis of the growing long bone metaphysis (1980)
    Springer
    Calcified tissue international 32 (1980), S. 113-122 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Bone ; Metaphysis ; Quantitative ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The purpose of this work was to analyze the proximal tibial metaphysis of the 170 g rat in a quantitative histologic fashion which would allow some relation to tissue age to be established. Stained 3 µm thick tissue sections were analyzed with the aid of a Merz grid on an eyepiece reticule and a light microscope. Tissue mass and cell distribution were studied in all areas. The rate of change in tissue mass during aging of the metaphysis was calculated. Two regions of the metaphysis were identified. One, corresponding to the primary spongiosa, less than 4.45 days of age, is a region of high turnover of hard tissue and high numbers of osteoblasts and osteoprogenitor cells. The other, corresponding to the secondary spongiosa, is a region of relatively low net tissue turnover and low numbers of osteoblasts and osteoprogenitor cells. Osteoclasts were found relatively more uniformly distributed through the metaphysis than were osteoblasts and osteoprogenitor cells. The rate of bone formation in the primary spongiosa is 50 times that found in the Haversian bone of the rib of 5-year-old humans and about 500 times that found at the cortical-endosteal surface of ribs of 5-year-old humans. It is argued that both cell distribution and tissue distribution in the metaphysis support the concept that osteoblasts and osteoclasts, rather than osteocytes, are responsible for the maturation of the metaphysis. The inhomogeneous distribution of both cells and tissue in the metaphysis has definite meaning for the interpretation of findings concerning the incorporation of radionuclides into the skeleton.
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    URL: http://dx.doi.org/10.1007/BF02408530
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  • 22
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    Role of growth hormone in experimental phosphorus deprivation in the rat (1980)
    Springer
    Calcified tissue international 32 (1980), S. 105-112 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Hypophysectomy ; Dietary phosphorus deprivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The demands of growth are known to exacerbate the effect of phosphorus deprivation (PD). We examined whether changes associated with PD could be prevented in young rats in which growth and growth hormone (GH) were eliminated by hypophysectomy (HPX) and whether PD in normal intact rats (INT) was associated with increased secretion of GH. INT or thyroxine- and ACTH-replaced HPX rats were fed one of the three diets: 0.31% P (NP); 0.027% P (LP), and 0.31% P, pair-fed with LP-mates (NP-PF). The results indicate that HPX did not qualitatively alter several physiologic responses to PD: (a) serum and urinary phosphorus (P) decreased and urinary calcium (Ca) increased; (b) net intestinal Ca retention fell and duodenal sac uptake of45Ca rose; and (c) external P balance was restored and duodenal sac uptake of32P-phosphate increased. Only the hypercalcemia seen in INT, LP rats was prevented by HPX. In INT rats serum immunoassayable GH levels, measured in single samples, were not different between different dietary groups while pituitary bioassayable GH was reduced in both LP and NP-PF rats when compared to the NP rats. Thus, except for hypercalcemia, the physiologic responses associated with PD are not prevented by the elimination of growth and GH, and the development of these responses in INT rats was not associated with a consistent or specific alteration in GH secretion.
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    URL: http://dx.doi.org/10.1007/BF02408529
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  • 23
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    Biphasic dose-response curves of cortisol effects on rat diaphyseal bone biomechanics (1992)
    Springer
    Calcified tissue international 50 (1992), S. 49-54 
    Details
    ISSN: 1432-0827
    Keywords: Cortisol ; Cortical bone ; Bone biomechanics ; Rat ; Femur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Doses of 8, 16 (low), 32, 48, 64 (medium), and 150 (high) mg/kg/day of cortisol were administered to groups of 8 growing rats each during 16 days, and their femurs were then submitted to 3-point bending tests at low strain rate. Low doses had no effect. Medium doses, previously shown to improve calcium (Ca) balance and weight gain in the species, augmented diaphyseal elastic and ultimate strength, stiffness, and plastic-to-elastic deformation ratio with respect to untreated controls. This effect was achieved either by enhancing bone mass (volume, sectional moment of inertia, wall/lumen ratio) without changes in material quality parameters (32 mg/kg/day) or, conversely, by increasing bone tissue mechanical properties (stress, modulus of elasticity) not affecting bone geometry (48 and 64 mg/kg/day). The highest dose, known to depress Ca balance and weight gain, impaired diaphyseal mechanical performance in controls by substantially reducing bone mass without major variation in bone material properties, that is, developing a true osteopenic state in mechanical terms. The energy elastically absorbed per unit volume (proportional to the risk of comminute fractures) was greater with the highest dose because of enhanced deformability and diminished bone mass. The biphasic dose-response curves obtained, grossly parallel to those previously demonstrated for metabolic actions of cortisol in the same species, showed that biomechanical repercussion of this treatment on bone depends on different, dose-dependent effects which vary independently in temporal course, intensity, and sign.
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    URL: http://dx.doi.org/10.1007/BF00297297
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    Different forms of alkaline phosphatase in adult rat femur. Effect of a Vitamin D3-deficient diet and of a sorbitol-enriched diet (1992)
    Springer
    Calcified tissue international 50 (1992), S. 433-438 
    Details
    ISSN: 1432-0827
    Keywords: Bone alkaline phosphatase ; Rat ; Vitamin D ; Sorbitol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In the femoral extremities of the adult rat containing the metaphysis, the epiphyseal cartilage, and the epiphysis, four alkaline phosphatase (AP) forms were distinguished on polyacrylamide gel electrophoresis. Two soluble forms were present in the 160,000 g supernatant: one of Mr 165 kDa and another of Mr 110–115 kDa, which exhibited a strong catalytical activity. Moreover, from the pellet, three membrane-bound forms of Mr 130, 110–115, and 100 kDa could be extacted with sodium deoxycholate. When denaturated AP was visualized by postelectrophoretic autoradiography of the phosphorylated intermediates, subunits always appeared as three monomers of Mr 75–80, 60–70, and 50–60 kDa. As four native forms but only three types of subunits were found to be present in the femur, it seems that, apart from homodimers, some heterodimers could also occur. Three types of diets were administered to three groups of rats for 5 weeks. Two are known to disturb bone mineralization: (1) a vitamin D3-deficient diet, and (2) the same as (1) but enriched with 12% sorbitol. The third was a normal diet containing vitamin D3. Concerning the effects on AP of dietary sorbitol and the vitamin D3-deficient diet, it was found that rats receiving the diet supplemented with sorbitol showed a substantial rise in the activity of the Mr 165 kDa form with the concomitant appearance of a new monomer of Mr 100 kDa. In contrast, rats fed the vitamin D3-deficient diet always displayed an increase in enzyme activity, principally of the Mr 100 and 110 kDa forms. In conclusion, the femur extracts of normal rats contained different forms of AP: either soluble 110–115 and 165 kDa forms or membrane-bound 130, 110–115, and 100 kDa forms. The administration of sorbitol-enriched diet induced a marked increase of the 165 kDa form whereas the administration of vitamin D3-deficient diet increased the 100 and 110 kDa forms.
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    URL: http://dx.doi.org/10.1007/BF00296774
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    Synthetic parathyroid hormone-like protein (1–74) is anabolic for bone in vivo (1992)
    Springer
    Calcified tissue international 51 (1992), S. 30-34 
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    ISSN: 1432-0827
    Keywords: PTHRP ; Anabolic ; Rat ; Bone ; Potency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parathyroid hormone-related protein (PTHRP) has recently been purified from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The gene encoding PTHRP has been cloned, and based on predicted amino acid sequence, polypeptides comprising the first 36 [36Tyr(1–36) PTHRP amide] and 74 [(1–74)PTHRP] amino acids have been synthesized. Human (h) PTHRP (1–36) and (1–74) are potent bone-resorbing agents, and are catabolic for bone in vivo when given continuously at high doses. Bovine parathyroid hormone (bPTH) (1–34) is also catabolic for bone at high dose levels, but when given in low doses for weeks to months, it is anabolic. Although PTHRP possess several PTH-like properties in bone, hPTHRP (1–34) is reported to be only weakly anabolic in vivo. As polypeptide length influences PTHRP action, we evaluated hPTHRP(1–74) as an anabolic agent for bone in vivo. Twenty-four 4-week-old male Sprague-Dawley rats were given daily subcutaneous injections of hPTHRP(1–74) (1 and 2 nmol/100 g body weight, bw), bPTH(1–34) (4 nmol/100 g bw) or vehicle. Rats were sacrificed on day 12, and serum calcium, phosphorus, and 1,25 dihydroxyvitamin D and femoral bone dry weight, calcium content, and hydroxyproline content were measured. Serum calcium and phosphorus were equivalent in all groups. A significant increase in dry bone weight was observed in both PTHRP-treated groups compared with controls. PTHRP also caused a significant, dose-dependent increase in bone calcium and hydroxypro-line content. Results of these studies indicate that PTHRP (1–74) is anabolic for bone in vivo when administered at low-dosage levels for a prolonged period.
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    URL: http://dx.doi.org/10.1007/BF00296214
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    Comparison of proteins synthesized in vivo and in vitro by mRNA from isolated protoplasts (1980)
    Springer
    Planta 148 (1980), S. 453-454 
    Details
    ISSN: 1432-2048
    Keywords: mRNA ; Protein synthesis ; Protoplasts ; Nicotiana ; Translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies of proteins synthesized in vitro by messenger RNA (mRNA) extracted from tobacco protoplasts showed that the changes in protein synthesis and especially the lack of certain proteins observed previously in isolated protoplasts did not result from a failure of translation.
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    URL: http://dx.doi.org/10.1007/BF02395314
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    Influence of leaves and roots on meristem development inNicotiana tabacum L. cv. Wisconsin 38 (1980)
    Springer
    Planta 148 (1980), S. 462-467 
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    ISSN: 1432-2048
    Keywords: Flower formation ; Leaves (in flower formation) ; Meristem (shoot) ; Nicotiana ; Roots (and flower formation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The terminal, apical shoot meristem ofN. tabacum cv. Wisconsin 38 normally differentiates into a flower after producing 30 to 40 nodes. The influence of leaves and roots on the regulation of flowering was evaluated by counting the number of nodes produced after removal of leaves or the induction of adventitious roots. Leaf removal has no effect on the number of nodes produced before flower formation. Root induction significantly increases the number of nodes produced before flower formation. The plant behaves as if it were measuring the number of nodes between the meristem and the roots as a means of regulating meristem conversion from vegetative to floral differentiation.
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    URL: http://dx.doi.org/10.1007/BF02395316
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    Polysomes from expanded tobacco leaves (1980)
    Springer
    Planta 148 (1980), S. 491-497 
    Details
    ISSN: 1432-2048
    Keywords: Leaves (polysomes) ; Nicotiana ; Polysomes ; Poly(A)+ RNA ; Protein synthesis ; RNA (polysomal, polyA+)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation of intact polysomes from leaves of tobacco (Nicotiana tabacum L.) is dependent on the age and state of development of leaves. Undegraded polysomes from young leaves in the early stages of expansion can be isolated easily by extracting the leaves in ice-cold extraction buffer (200 mM tris(hydroxymethyl)aminomethylmethane(Tris)-HCl, pH 9.0; 400 mM KCl; 200 mM sucrose; 35 mM MgCl2). Medium-size leaves give best yields of undegraded polysomes when extractions are carried out in the above buffer and in the presence of ethyleneglycol-bis-(β-amino-ethyl ether)-N,N′-tetracetic acid (EGTA) and mercaptoethanol. Isolation of polysomes from large, nearly fully expanded (mature) leaves requires all of the above plus diethyldithiocarbamate (DIECA) in the extraction medium. An extraction medium consisting of 25 mM EGTA, 0.01 M mercaptoethanol, 25 mM DIECA and 0.5% of the nonionic detergent, Nonidet-P40 (NP 40) was found to be very suitable for extraction of polysomes from all developmental stages of leaves. The polysomes extracted in the above medium showed active translation of protein in the wheat-germ in-vitro protein-synthesizing system. The translational products were similar when translations were carried out directly with polysomes or polysomal RNA, or polysomal poly(A)+ RNA from tobacco leaves. Poly(A)− polysomal RNA was a poor template in the in-vitro wheat-germ system.
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    URL: http://dx.doi.org/10.1007/BF02395320
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    Nutritional requirements of protoplast-derived, haploid tobacco cells grown at low cell densities in liquid medium (1980)
    Springer
    Planta 149 (1980), S. 7-18 
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    ISSN: 1432-2048
    Keywords: Auxin metabolism ; Cell suspensions (low density) ; Medium conditioning ; Nicotiana ; Nitrogen metabolism ; Protoplasts ; Vitamin requirements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Preliminary attempts to define a completely synthetic medium able to support divisions of haploid tobacco mesophyll protoplasts at low initial densities have failed. High protoplast concentrations together with large amounts of naphtaleneacetic acid in the medium (3 mg l-1 NAA) were required for maximal induction of protoplast division. However, cell suspensions derived from haploid protoplasts after four days of preculture at high initial cell densities could be diluted to densities as low as 1–4 cells ml-1, provided the concentration of NAA in the medium was lowered to below 0.3 mg l-1. The optimal NAA supply for low cell density growth was affected by the nature of the nitrogen source. A simple minimal medium which supports the growth of these haploid cells with a plating efficiency of 30–40%, independent of the cell density in the range of 1–4 to 3·104 cells ml-1, has been established. In this medium inositol was the only vitamin stringently required for growth. Growth of cells at low densities was also possible in a medium initially containing 3 mg l-1 NAA, provided it was conditioned by the growth of protoplasts at high densities. Preliminary experiments with [14C]NAA showed that the amount of free NAA remaining in the medium after preincubation at high densities was drastically reduced. Simultaneously, NAA conjugates accumulated in the medium. The implications of these results are discussed.
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    URL: http://dx.doi.org/10.1007/BF00386221
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    Characterization of a cytoplasmic auxin receptor from tobacco-pith callus (1980)
    Springer
    Planta 149 (1980), S. 44-47 
    Details
    ISSN: 1432-2048
    Keywords: Auxin receptor ; Callus ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultured tobacco-pith tissue contains a cytoplasmic receptor for indoleacetic acid (IAA). The concentration of binding sites is very low in comparison to that of several auxin receptors found by other investigators. A few obvious possible causes (degradation or inactivation) were investigated. From the results we conclude that the low number of binding sites is real. The receptor binds IAA optimally at pH 7.5–7.8 and at a temperature of 24–30°C, when incubated for 25–30 min. The binding is very specific, as is shown by competition experiments. The concentration of the receptor in the callus tissue changes dramatically during each culture period, which suggests a possible role in development. The receptor was partly purified by gel filtration on Sepharose 6B followed by ion-exchange chromatography on DEAE-cellulose.
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    URL: http://dx.doi.org/10.1007/BF00386225
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    The effect of light on the production of ethylene from 1-aminocyclopropane-1-carboxylic acid by leaves (1980)
    Springer
    Planta 149 (1980), S. 196-199 
    Details
    ISSN: 1432-2048
    Keywords: 1-Aminocyclopropane-1-carboxylic acid ; Avena ; Ethylene ; Etiolation ; Light (ethylene production) ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract White light inhibits the conversion of 1-amino-cyclopropane-1-carboxylic acid (ACC) in discs of green leaves of tobacco (Nicotiana tabacum L.) and segments of oat (Avena sativa L.) leaves by from 60 to 90%. Etiolated oat leaves do not show this effect. The general nature of the effect is shown by its presence in both a mono- and a dicotyledon. Since the leaves have been grown and pre-incubated in light, yet can produce from 2 to 9 times as much ethylene in the dark as in the light, it follows that the light inhibition is fully reversible. The inhibition by light is about equal to that exerted in the dark by CoCl2; it can be partly reversed by dithiothreitol and completely by mercaptoethanol. Thus the light is probably acting, via the photosynthetic system, on the SH group(s) of the enzyme system converting ACC to ethylene.
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    Correlation between the nicotine content of tobacco plants and callus cultures (1980)
    Springer
    Planta 149 (1980), S. 205-206 
    Details
    ISSN: 1432-2048
    Keywords: Callus cultures ; Nicotiana ; Nicotine ; Tissue cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Callus cultures of two low-alkaloid lines of Nicotiana tabacum L. had considerably lower nicotine contents than cultures from the respective highalkaloid cultivars which were isogenic except for the two loci for alkaloid accumulation. Thus, there was a strong correlation between the nicotine content of callus cultures and the plants from which they were derived.
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    URL: http://dx.doi.org/10.1007/BF00380884
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    Auxin-binding by particulate fractions from tobacco leaf protoplasts (1980)
    Springer
    Planta 150 (1980), S. 9-12 
    Details
    ISSN: 1432-2048
    Keywords: Auxin binding ; Nicotiana ; Plasma membrane ; Protoplast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro binding of 1-naphthaleneacetic acid (NAA) to particulate fractions from tobacco leaf protoplasts was studied. In freshly isolated protoplasts no specific binding could be detected, whereas it was present in particulate fractions from tobacco leaves. It is concluded that the NAA-binding-sites are probably located at the external face of the plasma membrane; they are destroyed during protoplast isolation by proteolytic enzymes in the cellulase and macerozyme preparations. After culturing the protoplasts for 3–4 d, the first cell divisions were observed and at the same time specific NAA-binding became detectable. The affinity constant for NAA was approx. 2·106 mol-1 and the number of binding sites increased during further culture.
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    URL: http://dx.doi.org/10.1007/BF00385607
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    Factors influencing the incidence of habituation for cytokinin of tobacco pith tissue in culture (1980)
    Springer
    Planta 150 (1980), S. 264-268 
    Details
    ISSN: 1432-2048
    Keywords: Cytokinin habituation ; Habituation, cytokinin ; Nicotiana ; Position effects (habituation) ; Size effects (habituation) ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pith tissue of Nicotiana tabacum L. cv. “Havana 425” exhibits a gradient in its tendency to habituate for cytokinin on an auxin-containing medium at 35° C, about 10° C above the standard culture temperature. Explants of pith from below the 8th to 11th internode, counting from the bottom of the plant, rarely habituate for cytokinin; explants from above this threshold habituate rapidly. The explants must also be above a critical size, about 20–30 mg, to habituate. There was a pronounced interaction between size and position effects; the threshold position for cytokinin habituation shifted upward with decreasing explant size.
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    URL: http://dx.doi.org/10.1007/BF00390836
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    Stimulation by abscisic acid of RNA synthesis in discs from healthy and tobacco mosaic virus-infected tobacco leaves (1980)
    Springer
    Planta 150 (1980), S. 349-353 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid ; Nicotiana ; Ribonucleic acid synthesis ; Tobacco mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Uptake of abscisic acid from the culture medium by discs of healthy and tobacco mosaic virus-infected tobacco leaves was measured. Small (two to five-fold) increases in abscisic acid concentration in discs caused increases in rates of [3H]uridine and [3H]adenine incorporation into total nucleic acid, virus RNA and host ribosomal RNA. Net accumulation of virus RNA was also enhanced by abscisic acid. This evidence for stimulation of RNA synthesis is compared with previous reports showing inhibition of RNA synthesis in other tissues. It is suggested that the increase in endogenous abscisic acid caused by tobacco mosaic virus infection may be at least partly responsible for observed increases in rates of RNA synthesis after infection.
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    URL: http://dx.doi.org/10.1007/BF00390168
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    Periodic deposition of arabinogalactan epitopes in the cell wall of pollen tubes of Nicotiana tabacum L. (1992)
    Springer
    Planta 188 (1992), S. 532-538 
    Details
    ISSN: 1432-2048
    Keywords: Arabinogalactan epitope (immunofluores-cence localization) ; Cell wall ; Monoclonal antibody (JIM 8, MAC 207) ; Nicotiana ; Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The monoclonal antibodies MAC 207 and JIM 8, recognizing arabinogalactan epitopes, were used to localize the corresponding antigenic sites in pollen tubes of Nicotiana tabacum L. grown in vitro or semi in vivo. The analysis of the immunofluorescence labelling was performed by means of confocal laser scanning microscopy. Most pollen tubes were labelled along their length, with the exception of the tip region, in a ring-like pattern with remarkable periodicity. The diameter of the rings was approx. 12 μm and the distance between two rings was about 6 μm. No labelling of the cytoplasm, the vegetative nucleus or the generative cell was observed. The presence of labelling in the non-apical tube wall after pectinase and cellulase digestion indicates that the epitopes for MAC 207 and JIM 8 are located in the inner callosic sheath of the pollen-tube wall.
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    URL: http://dx.doi.org/10.1007/BF00197045
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    The role of peroxidase isoenzyme groups of Nicotiana tabacum in hydrogen peroxide formation (1980)
    Springer
    Planta 147 (1980), S. 467-470 
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    ISSN: 1432-2048
    Keywords: Hydrogenperoxide ; Lignification ; Nicotiana ; Peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three peroxidase isoenzyme-groups found in cell walls of tobacco were tested for their capacity to form H2O2. Isoenzyme-group GI, located only in cell walls (GII and GIII are also found in protoplasts) showed the highest Kapp-value for H2O2-formation. The lowest Kapp-value, i.e., maximal H2O2-formation was received for group GIII which is ionically bound to the cell wall. As shown before, GI yields maximal polymerization rates for coniferyl- and p-coumarylalcohol. These facts indicate that each of the peroxidase isoenzyme groups of the cell wall is involved with different catalytic functions within the same pathways of H2O2-formation and succeeding lignification. H2O2-formation catalyzed by all 3 groups was increased by very low concentrations of Mn2+-ions. The required amount of Mn2+ leading to maximal stimulation was in each case dependent on the basic rate of H2O2-formation. Maximal stimulation of H2O2-formation by phenolic compounds was achieved by coniferylalcohol at a concentration of 10-4M for all groups. Stimulation by p-coumaryl-and by sinapylalcohol was not as significant.
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    The induction of cytokinin habituation in primary pith explants of tobacco (1980)
    Springer
    Planta 149 (1980), S. 402-407 
    Details
    ISSN: 1432-2048
    Keywords: Cytokinin ; Habituation rates ; Nicotiana ; Temperature and habituation ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pith parenchyma tissue ofNicotiana tabacum L. cv. “Havana 425” becomes cytokinin habituated when incubated at 35°C on an auxin-containing medium. Under these conditions, habituated, hyperplastic nodules appear on the tissues. We used these nodules to estimate the incidence of habituation by a statistical method. The rate of habituation varied with the season. Tissue isolated from plants in the spring habituated approx. 7 times faster than did tissue isolated from plants in winter. The fact that the average rate, 〉4×10−3 per cell generation, was 100–1,000 times faster than the rate of somatic mutation inNicotiana species and depended on the physiological state of the tissue provides further evidence that habituation involves epigenetic changes rather than rare, random genetic mutations. We also found that kinetin (6-furfurylaminopurine) induced habituation and that the concentration required depended on the duration of cytokinin treatment. For long incubation times, approx. 6×10−10 M kinetin, which is about 1,000-fold lower than the concentration optimal for growth of cytokinin-requiring pith tissue, was sufficient to induce habituation. These results support the hypothesis that the habituated state is maintained by a positive feedback loop in which cytokinins either induce their own synthesis or inhibit their own degradation.
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    Fatty-acid composition and biosynthesis in cell suspension cultures of Glycine max (L.) Merr., Catharanthus roseus G. Don and Nicotiana tabacum L. (1980)
    Springer
    Planta 147 (1980), S. 384-388 
    Details
    ISSN: 1432-2048
    Keywords: Acetate incorporation ; Catharanthus ; Cell suspension cultures ; Fatty acids ; Glycihe ; Nicotiana ; Temperature and fatty-acid synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fatty-acid composition of C. roseus and N. tabacum cell suspension cultures was unaffected by subculture on Wood and Braun, Murashige and Skoog, or Gamborg B5C media. However, placing the cultures — which were normally grown at 25° C — at 15° C reduced growth but resulted in enhanced formation of oleic and linolenic acids in C. roseus cultures and increased levels of linoleic and linolenic acids in cultures of G. max and N. tabacum, respectively. The incorporation of [14C]acetate into [14C]linoleic acid was more rapid in N. tabacum cells than in G. max cells, but was very poor in C. roseus where the [14C] label was distributed mainly between palmitic and oleic acids.
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    URL: http://dx.doi.org/10.1007/BF00380177
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    Expression of nuclear and chloroplastic genes coding for fraction-1 protein in somatic hybrids of Nicotiana tabacum + rustica (1980)
    Springer
    Planta 147 (1980), S. 414-417 
    Details
    ISSN: 1432-2048
    Keywords: Fraction-1 protein ; Hybrid, somatic ; Nicotiana ; Protein (Fraction 1) ; Ribulose-1,5-bisphosphate carboxylase ; Somatic hybrid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the sexual interspecific cross, Nicotiana rustica L.xN. tabacum L., N. rustica can serve as the female but not as the male parent. By fusion of protoplasts, the barrier to fertilization was overcome and somatic hybrids containing N. tabacum cytoplasm were produced as shown by isoelectric focusing of the Fraction-1 protein (F-1-protein). All somatic hybrids displayed polypeptides of the large subunit of F-1 protein (which is coded by the chloroplast genome) characteristic of only one or the other parental species. Two hybrids had large subunits of the N. tabacum type and two hybrids had those of the N. rustica type. Three hybrids contained three smallsubunit polypeptides (coded by the nuclear genome), one being characteristic of N. rustica, one characteristic of N. tabacum, and one with an isoelectric point common to both species. A fourth hybrid contained only two small-subunit polypeptides of the N. tabacum type but in a F-1 protein macromolecule whose large subunits were of the N. rustica type. One somatic hybrid was self-fertile and its F2 progeny contained large- and small-subunit polypeptides indistinguishable in their isoelectric points from those in the parent F1 hybrid. All somatic hybrids showed an aneuploid chromosome number and morphological characteristics intermediate between those of N. rustica and N. tabacum.
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    URL: http://dx.doi.org/10.1007/BF00380181
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    The effect of different temperatures on fatty-acid synthesis and polyunsaturation in cell suspension cultures (1980)
    Springer
    Planta 147 (1980), S. 389-395 
    Details
    ISSN: 1432-2048
    Keywords: Catharanthus ; Cell suspension cultures ; Glycine ; Fatty acids (synthesis, desaturation) ; Nicotiana ; Linoleic, linolenic, oleic, acids ; Temperature and fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell suspension cultures of Catharanthus roseus G. Don, Glycine max (L.) Merr. and Nicotiana tabacum L. were incubated with [14C]acetate, [14C]oleic acid and [14C]linoleic acid at five different temperatures ranging from 15 to 35° C. When the incubation temperature was increased, [14C]acetate was incorporated preferentially into [14C]palmitate, with a concomitant drop in [14C]oleate formation. Between 15 and 20° C, [14C]oleic acid accumulated in C. roseus cells. In all cultures, optimum desaturation of [14C]oleic acid to [14C]linoleic acid occurred between 20 and 25° C, and in G. max this was also the optimal range for desaturation of [14C]linoleic acid to [14C]linolenic acid. Elongation of [14C]palmitic acid was inhibited when cultures grown at 15° C for 25 h were subsequently incubated with [14C]acetate at 25° C. [14C]oleic acid accumulated in G. max and C. roseus cultures grown at 35° C for 25 h and subsequently incubated at 25° C. Desaturation of [14C]oleic acid increased up to 25° C, but then decreased or leveled off depending on the cell line and on the temperature prior to incubation.
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    Polysomes from expanded tobacco leaves (1980)
    Springer
    Planta 148 (1980), S. 491-497 
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    ISSN: 1432-2048
    Keywords: Leaves (polysomes) ; Nicotiana ; Polysomes ; Poly(A)+ RNA ; Protein synthesis ; RNA (polysomal, polyA+)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation of intact polysomes from leaves of tobacco (Nicotiana tabacum L.) is dependent on the age and state of development of leaves. Undegraded polysomes from young leaves in the early stages of expansion can be isolated easily by extracting the leaves in ice-cold extraction buffer (200 mM tris(hydroxymethyl)aminomethylmethane(Tris)-HCl, pH 9.0; 400 mM KCl; 200 mM sucrose; 35 mM MgCl2). Medium-size leaves give best yields of undegraded polysomes when extractions are carried out in the above buffer and in the presence of ethyleneglycol-bis-(β-amino-ethyl ether)-N,N′-tetracetic acid (EGTA) and mercaptoethanol. Isolation of polysomes from large, nearly fully expanded (mature) leaves requires all of the above plus diethyldithiocarbamate (DIECA) in the extraction medium. An extraction medium consisting of 25 mM EGTA, 0.01 M mercaptoethanol, 25 mM DIECA and 0.5% of the nonionic detergent, Nonidet-P40 (NP 40) was found to be very suitable for extraction of polysomes from all developmental stages of leaves. The polysomes extracted in the above medium showed active translation of protein in the wheat-germ in-vitro protein-synthesizing system. The translational products were similar when translations were carried out directly with polysomes or polysomal RNA, or polysomal poly(A)+ RNA from tobacco leaves. Poly(A)− polysomal RNA was a poor template in the in-vitro wheat-germ system.
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    URL: http://dx.doi.org/10.1007/BF00552665
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    Suitable conditions for characterization, identification, and isolation of the mRNA of the small subunit of ribulose-1,5-bisphosphate carboxylase from Nicotiana sylvestris (1980)
    Springer
    Planta 148 (1980), S. 211-216 
    Details
    ISSN: 1432-2048
    Keywords: mRNA ; Nicotiana ; Protein synthesis ; Ribulose-1,5-bisphosphate carboxylase ; RNA (messenger) ; Translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The products synthesized in vitro by messenger RNA (mRNA) extracted from Nicotiana sylvestris were analyzed by electrophoresis on polyacrylamide slab gels. Only three of the major polypeptides synthesized are considered here: P55, P32, and P20. P55 and P32 were translated from chloroplast mRNA. P55 corresponds to the large subunit of ribulose-1,5-bisphosphate (RuP2) carboxylase; P32 is probably a chloroplast membrane protein. P20, the polypeptide synthesized from cytoplasmic poly(A)+ RNA, is the precursor of the small subunit of RuP2 carboxylase. The balance between P20 and P32, in which their relative proportions varied inversely, was regulated by the age of the leaves and the time of illumination; we took advantage of this phenomenon to isolate the mRNA from the small subunit in relatively large amounts. This mRNA has a molecular weight of 350,000.
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    Properties and regulation of adenosine 5′-phosphosulfate sulfotransferase from suspension cultures ofNicotiana sylvestris (1980)
    Springer
    Planta 150 (1980), S. 140-143 
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    ISSN: 1432-2048
    Keywords: Adenosine 5′-phosphosulfate sulfotransferase ; Cell suspension culture ; Cysteine ; Enzyme regulation ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The properties and the regulation of adenosine 5′-phosphosulfate sulfotransferase extracted from cell suspension cultures ofNicotiana sylvestris was investigated. Optimal adenosine 5′-phosphosulfate sulfotransferase activity was obtained from the cells by extraction with 0.1 M tris-HCl, pH8.0, containing 2 M MgSO4 and 10 mM dithioerythritol. The K m for adenosine 5′-phosphosulfate in the sulfotransferase reaction was about 11 μM. Adenosine 5′-phosphosulfate in concentrations above 50 μM were inhibitory. The extratable adenosine 5′-phosphosulfate sulfotransferase activity decreased during cultivation with sulfate as the sole sulfur source, but after about 3 days it reached a constant level (50 to 100 nmol activated sulfate transferred h-1 mg-1 protein) which was maintained for at least 24 h. Addition of 0.5 mM cysteine to the culture medium decreased the extractable adenosine 5′-phosphosulfate sulfotransferase activity and blocked growth completely. With 0.1 mM cysteine an enzyme level of about 10% of the initial value was reached within 6 to 12 h without significant inhibition of growth. The added cysteine was absorbed rapidly and after 24 h cysteine could no longer be detected in the medium. Before the cysteine was completely depleted, the activity of adenosine 5′-phosphosulfate sulfotransferase started to increase, reaching ultimately a level which was comparable to the initial value.
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    Ribosylzeatin and zeatin in tobacco crown gall tissue (1980)
    Springer
    Planta 147 (1980), S. 269-273 
    Details
    ISSN: 1432-2048
    Keywords: Crown gall ; Cytokinins ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytokinins were extracted from two cultures of tobacco crown gall tumor tissue: an unorganized tissue and a teratoma which produced leafy shoots. On Sephadex LH-20 column chromatography, extracts of both types of tissue yielded two peaks of cytokinin activity with elution volumes similar to ribosylzeatin and zeatin. Ribosylzeatin and zeatin were detected and quantified by coupled gas chromatography — mass spectrometry selected ion monitoring (GC/MS SIM), comparable quantities being found in the two extracts. Full mass spectral evidence for the presence of ribosylzeatin in both tissues was obtained. No evidence was found for the presence of N6-(Δ2-isopentenyl)adenosine (i6Ade) or N6-(Δ2-isopentenyl)adenine (i6Ade) although these compounds have been reported to occur in cytokinin-habituated tobacco callus tissues.
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    Multistage disruption of protoplasts by dikegulac (1980)
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    Planta 147 (1980), S. 274-276 
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    ISSN: 1432-2048
    Keywords: Cell division ; Dikegulac ; Lysis ; Nicotiana ; Plasmalemma ; Protoplasts ; Tonoplast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dikegulac (2,3:4,6 di-o-isopropylidine-2-keto-I-gulonate) is a growth regulator used to differentially kill terminal apices, and it analogously inhibits basic metabolic functions in dividing cells, but not stationary cells, in suspension culture. This report demonstrates an analogous situation in isolated tobacco protoplasts. At the lowest concentrations, dikegulac partially suppresses division of the protoplasts. Higher concentrations are required to produce visual cytoplasmic damage to the protoplasts, which probably first occurs at the level of the plasmalemma, as the vacuoles can be released intact. Later, tonoplast disruption occurs.
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    Isolation of abscisic acid-resistant variants from tobacco cell cultures (1980)
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    Planta 148 (1980), S. 97-102 
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    ISSN: 1432-2048
    Keywords: Abscisic acid ; Cell cultures ; Nicotiana ; Variants, resistant ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The goal of this work was to begin a genetic study of the molecular mode of action of abscisic acid (ABA), by isolating variant cultured cells resistant to the hormone, or to a factor which induces ABA synthesis, namely water stress. Cell cultures of Nicotiana tabacum L. cv. Wisconsin 38 and N. silvestris Speg. and Comes were chosen as the experimental materials. Studies of the effects of the two stresses on the growth of the cultures demonstrated that ABA or water stress imposed by mannitol could completely inhibit growth. These effects arose in both cases from a constant reduction of the growth rate of the cells throughout the culture period. Mannitol also induced an increase in ABA content of the cells and media of suspension cultures, although not to the concentrations required to achieve the same degree of growth inhibition when the hormone was applied exogenously.
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    Isolation of abscisic acid-resistant variants from tobacco cell cultures (1980)
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    Planta 148 (1980), S. 103-107 
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    ISSN: 1432-2048
    Keywords: Abscisic acid ; Cell cultures ; Nicotiana ; Variants, resistant ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variant clones were isolated from Nicotiana silvestris Speg. et Comes cell cultures at low frequencies following severe abscisic-acid (ABA) or mannitol-induced water-stress treatments of plated cells. N. tabacum L. variants were not recovered. Variants from the ABA selection experiments exhibited a 10-fold increase in resistance to the hormone. This trait was stable in non-selective conditions for as long as was tested (200 days), but did not alter the response of the cells to water stress. Cell lines from the waterstress selection were not more resistant to mannitol than the parent line, and had a wide range of response to ABA.
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    Comparison of proteins synthesized in vivo and in vitro by mRNA from isolated protoplasts (1980)
    Springer
    Planta 148 (1980), S. 453-454 
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    ISSN: 1432-2048
    Keywords: mRNA ; Protein synthesis ; Protoplasts ; Nicotiana ; Translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies of proteins synthesized in vitro by messenger RNA (mRNA) extracted from tobacco protoplasts showed that the changes in protein synthesis and especially the lack of certain proteins observed previously in isolated protoplasts did not result from a failure of translation.
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    Influence of leaves and roots on meristem development inNicotiana tabacum L. cv. Wisconsin 38 (1980)
    Springer
    Planta 148 (1980), S. 462-467 
    Details
    ISSN: 1432-2048
    Keywords: Flower formation ; Leaves (in flower formation) ; Meristem (shoot) ; Nicotiana ; Roots (and flower formation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The terminal, apical shoot meristem ofN. tabacum cv. Wisconsin 38 normally differentiates into a flower after producing 30 to 40 nodes. The influence of leaves and roots on the regulation of flowering was evaluated by counting the number of nodes produced after removal of leaves or the induction of adventitious roots. Leaf removal has no effect on the number of nodes produced before flower formation. Root induction significantly increases the number of nodes produced before flower formation. The plant behaves as if it were measuring the number of nodes between the meristem and the roots as a means of regulating meristem conversion from vegetative to floral differentiation.
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    CMS system inNicotiana: flower development, patterns of mitochondrial DNA and mitochondrial gene expression (1992)
    Springer
    Sexual plant reproduction 5 (1992), S. 13-26 
    Details
    ISSN: 1432-2145
    Keywords: Nicotiana ; Cytoplasmic male sterility ; Flower morphogenesis ; mtDNA organization ; In organello protein synthesis ; Mitochondrial transcripts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A detailed description of in planta floral ontogeny based on scanning electron microscopy, developmental histology and morphology is presented for three different alloplasmic gene-cytoplasmic male-sterile (CMS)Nicotiana tabacum isonuclear lines with cytoplasms ofN. bigelovii, N. debneyi and N. suaveolens and compared to the corresponding nuclear donorN. tabacum genotype. This allowed the precise determination of the developmental stages affected in the mutant forms as well as a thorough phenotypic characterization of them. The organization of the mitochondrial genome and expression of mitochondrial DNA (mtDNA) was investigated in the three different alloplasmic CMS tobacco analogs and compared to the corresponding malefertile parentalNicotiana species. Southern hybridizations of total cellular DNA and mtDNA from the different sets of lines with probes specific for mitochondrial genes coding for cytochrome oxidase subunits I, II and III, apocytochrome b, ATPase subunits α and 9 as well as 18S-5S ribosomal RNA indicated that: (a) mtDNA organization is different between mitochondrial genomes of fertile and sterile lines but identical in two different fertile tobacco lines; however genetic similarity among different mitochondrial genome types can be revealed by restriction fragment patterns; (b) although several differences were detected between the male-sterile and male-fertile plants, most of these were related to the origin of the mitochondria (cytoplasm donorNicotiana species); (c) identical mtDNA rearrangements — distinct to the cytoplasm donor — occur in cytoplasmic malesterile tobacco analogs bearing cytoplasm fromN. bigelovii in two differentN. tabacum nuclear backgrounds, indicating that mitochondrial genome structure inNicotiana is altered by substitution of the nuclear back-ground, since (d) inter- and intraspecific mitochondrial genome diversity among differentNicotiana species and the corresponding alloplasmic CMS tobacco analogs can be determined by hybridization with mtDNA specific probes. Analysis of in organello translation products in the three CMS-systems described confirmed the presence of variant proteins synthesized by mitochondria from CMS and male-fertileNicotiana isonuclear lines. In addition, differences due to the origin of both the nucleus and the cytoplasm, which involve changes in the presence or size of particular polypeptides, are apparent. A common feature of all three systems — including two different nuclear backgrounds — is the enhanced synthesis of a 31-kDa polypeptide in the strictly isonuclear CMS lines compared to the male-fertile tobacco. In addition, organellar gene expression was studied by Northern blot analysis of transcripts homologous to mitochondrial gene probes, revealing variant mtRNA species associated with some CMS lines.
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    Synergid degeneration in Nicotiana: a quantitative, fluorochromatic and chlorotetracycline study (1992)
    Springer
    Sexual plant reproduction 5 (1992), S. 151-155 
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    ISSN: 1432-2145
    Keywords: Calcium ; Chlorotetracycline ; Fertilization ; Nicotiana ; Synergid degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Synergid degeneration was examined in the isolated embryo sac and egg apparatus of Nicotiana tabacum using quantitative cytology, fluorochromatic reaction (FCR) and chlorotetracycline (CTC). Most synergid degeneration occurs after pollen tubes (PT) arrive in the ovarian chamber between 42 and 48 h after pollination; synergid degeneration was precluded when PT were prevented from entering the ovary by stylar excision indicating that the signal that triggers synergid degeneration travels only relatively short distances in this plant. There was no evidence for any preferentiality between right or left synergids with regard to cell size or degeneration pattern. FCR staining confirms that synergid degeneration involves the loss of membrane integrity and is a reliable indicator of the onset of degeneration. CTC labeling of the degenerated synergid reveals that a concentrated reserve of membrane-bound calcium is present in the receptive synergid, possibly aiding in the attraction, arrest and discharge of the PT, releasing the sperms into the receptive ES.
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    Video microscopic observations of living, isolated embryo sacs of Nicotiana and their component cells (1992)
    Springer
    Sexual plant reproduction 5 (1992), S. 156-162 
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    ISSN: 1432-2145
    Keywords: Female germ unit ; Nicotiana ; Megagametophyte ; Organelle movement ; Video microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Living embryo sacs and megagametophytic cells of Nicotiana alata and Nicotiana tabacum were obtained using enzymatic maceration and microdissection. The yields of isolated embryo sacs, egg apparatus and central cells were up to 35%, 40% and 35%, respectively. Vectorial movement of organelles and undulations of tubular structures, presumably endoplasmic reticulum, were observed in eggs, synergids and central cells using video-enhanced microscopy. Despite evident viability using the fluorochromatic reaction, the egg displays much less organelle movement and therefore appears to be quiescent. The large vacuole of the central cell is traversed by mobile strands of cytoplasm through which organelles migrate. A polygonal network is located at the periphery of the central cell, which may contribute to anchorage of the cell with the embryo-sac wall. The observation of organelle movement provides direct evidence of the condition of the cell and may be a useful approach for assessing cell vigor.
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    The tRNATyr multigene family of Nicotiana rustica: genome organization, sequence analyses and expression in vitro (1992)
    Springer
    Plant molecular biology 20 (1992), S. 869-878 
    Details
    ISSN: 1573-5028
    Keywords: genome organization ; in vitro transcription ; in vitro splicing ; Nicotiana ; tyrosine tRNA genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tobacco tRNATyr genes are mainly organized as a dispersed multigene family as shown by hybridization with a tRNATyr-specific probe to Southern blots of Eco RI-digested DNA. A Nicotiana genomic library was prepared by Eco RI digestion of nuclear DNA, ligation of the fragments into the vector λgtWES·λB and in vitro packaging. The phage library was screened with a 5′-labelled synthetic oligonucleotide complementary to nucleotides 18 to 37 of cytoplasmic tobacco tRNATyr. Eleven hybridizing Eco RI fragments ranging in size from 1.7 to 7.5 kb were isolated from recombinant lambda phage and subcloned into pUC19 plasmid. Four of the sequenced tRNATyr genes code for the known tobacco tRNA1 Tyr (GψA) and seven code for tRNA2 Tyr (GψA). The two tRNA species differ in one nucleotide pair at the basis of the TψC stem. Only one tRNATyr gene (pNtY5) contains a point mutation (T54→A54). Comparison of the intervening sequences reveals that they differ considerably in length and sequence. Maturation of intron-containing pre-tRNAs was studied in HeLa and wheat germ extracts. All pre-tRNAsTyr-with one exception-are processed and spliced in both extracts. The tRNATyr gene encoded by pNtY5 is transcribed efficiently in HeLa extract but processing of the pre-tRNA is impaired.
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    The xylanase introns from Cryptococcus albidus are accurately spliced in transgenic tobacco plants (1992)
    Springer
    Plant molecular biology 18 (1992), S. 447-451 
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    ISSN: 1573-5028
    Keywords: mRNA processing ; Nicotiana ; polymerase chain reaction ; sequencing ; transcription ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The xylanase gene from Cryptococcus albidus contains seven introns. Genomic and cDNA clones under the control of the CaMV 35S promoter were transferred into tobacco plants using Agrobacterium-mediated cell transformation. The genes were transcribed and the mRNAs were amplified by the polymerase chain reaction using primers on each side of the intron region. About 90% of the amplification products from plants transformed with the genomic clone corresponded to the size of the pre-mRNA (1.2 kb) and 10% represented the spliced product (0.85 kb). The 0.85 kb fragment was cloned and sequenced and the result indicated that the introns from the xylanase gene were accurately spliced by the plant cells.
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    URL: http://dx.doi.org/10.1007/BF00040660
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    Photosystem II 23 kDa polypeptide of oxygen-evolving complex is encoded by a multigene family in tobacco (1992)
    Springer
    Plant molecular biology 18 (1992), S. 997-999 
    Details
    ISSN: 1573-5028
    Keywords: gene family ; Nicotiana ; oxygen evolution ; photosystem ; polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00019217
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    Inorganic pyrophosphate content and metabolites in potato and tobacco plants expressing E. coli pyrophosphatase in their cytosol (1992)
    Springer
    Planta 188 (1992), S. 238-244 
    Details
    ISSN: 1432-2048
    Keywords: Inorganic pyrophosphate ; Nicotiana ; Sinksource ; Solanum ; Sucrose metabolism ; Transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Metabolite levels and carbohydrates were investigated in the leaves of tobacco (Nicotiana tabacum L.) and leaves and tubers of potato (Solanum tuberosum L.) plants which had been transformed with pyrophosphatase from Escherichia coli. In tobacco the leaves contained two- to threefold less pyrophosphate than controls and showed a large increase in UDP-glucose, relative to hexose phosphate. There was a large accumulation of sucrose, hexoses and starch, but the soluble sugars increased more than starch. Growth of the stem and roots was inhibited and starch, sucrose and hexoses accumulated. In potato, the leaves contained two- to threefold less pyrophosphate and an increased UDP-glucose/ hexose-phosphate ratio. Sucrose increased and starch decreased. The plants produced a larger number of smaller tubers which contained more sucrose and less starch. The tubers contained threefold higher UDP-glucose, threefold lower hexose-phosphates, glycerate-3-phosphate and phosphoenolpyruvate, and up to sixfold more fructose-2,6-bisphosphatase than the wild-type tubers. It is concluded that removal of pyrophosphate from the cytosol inhibits plant growth. It is discussed how these results provide evidence that sucrose mobilisation via sucrose synthase provides one key site at which pyrophosphate is needed for plant growth, but is certainly not the only site at which pyrophosphate plays a crucial role.
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    URL: http://dx.doi.org/10.1007/BF00216819
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    Intracellular transport and processing of a tobacco vacuolar β-1,3-glucanase (1992)
    Springer
    Planta 188 (1992), S. 559-565 
    Details
    ISSN: 1432-2048
    Keywords: Chitinase ; C-terminal processing ; β-1,3-glucanase ; Glycosylation ; Nicotiana ; Pathogenesis-related proteins ; Vacuole (targeting)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The class I β-1,3-glucanases are basic, vacuolar enzymes implicated in the defense of plants against pathogen infection. The tobacco (Nicotiana tabacum L.) enzyme is synthesized as a preproprotein with an N-terminal signal peptide for targeting to the lumen of the endoplasmic reticulum and an N-glycosylated C-terminal extension which is lost during protein maturation. The transport and processing of β-1,3-glucanase in cellsuspension cultures of the tobacco cultivar Havana 425 was investigated by pulse-chase labelling and cell fractionation. We verified that mature β-1,3-glucanase is localized in the vacuole of the suspension-cultured cells. Comparison of the time course of processing in homogenates, the soluble fraction, and membrane fractions indicates that proglucanase is transported from the endoplasmic reticulum via the Golgi compartment to the vacuole. Processing to the mature form occurs in the vacuole. Treatment of cells with tunicamycin, which inhibits N-glycosylation, and digestion of the 35S-labelled processing intermediates with endoglycosidase H indicate that β-1,3-glucanase has a single N-glycan attached to the C-terminal extension. Glycosylation is not required for proteolytic processing or correct targeting to the vacuole.
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    URL: http://dx.doi.org/10.1007/BF00197049
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    Physical maps of Nicotiana chloroplast DNA constructed by an efficient procedure (1992)
    Springer
    Theoretical and applied genetics 83 (1992), S. 515-527 
    Details
    ISSN: 1432-2242
    Keywords: Nicotiana ; Chloroplast DNA ; Restriction patterns ; Physical mapping ; Restriction site variations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The restriction profiles of chloroplast DNA (cpDNA) from Nicotiana tabacum, N. sylvestris, N. plumbaginifolia, and N. otophora were obtained with respect to AvaI, BamHI, BglI, HindIII, PstI, PvuII, SalI, and XhoI. An efficient mapping method for the construction of cpDNA physical maps in Nicotiana was established via a computer-aided analysis of the complete cpDNA sequence of N. tabacum for probe selection. The efficiency of this approach is demonstrated by the determination of cpDNA maps from N. sylvestris, N. plumbaginifolia, and N. otophora with respect to all of the above restriction endonucleases. The size and basic structure of the cpDNA from the three species are almost identical, with an addition of approximately 80 bp in N. plumbaginifolia. The restriction patterns and hence the physical maps between N. tabacum and N. sylvestris cpDNA are identical and there is no difference in the Pvull digests of cpDNA from all four species. Restriction site variations in cpDNA from different species probably result from point mutations, which create or eliminate a particular cutting site, and they were observed spanning the whole chloroplast molecule but highly concentrated in both ends of the large, single-copy region. The results presented here will be used for the forthcoming characterization of chloroplast genomes in the interspecies somatic hybrids of Nicotiana, and will be of great value in completing the exploration of the phylogenetic relationships within this already extensively studied genus.
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    URL: http://dx.doi.org/10.1007/BF00226542
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    Spontaneous extensive chromosome elimination in somatic hybrids between somatically congruent species Nicotiana tabacum L. and Atropa belladonna L. (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 87-91 
    Details
    ISSN: 1432-2242
    Keywords: Somatic cell fusion ; Asymmetric hybrids ; Atropa ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mesophyll protoplasts of the kanamycin-resistant nightshade, Atropa belladonna, were fused with mesophyll protoplasts of the phosphinothricin resistant-tobacco, Nicotiana tabacum. A total of 447 colonies resistant to both inhibitors was selected. Most of them regenerated shoots with morphology similar to one of the earlier obtained and described symmetric somatic hybrids Nicotiana + Atropa. However, three colonies (0.2%) regenerated vigorously growing tobacco-like shoots; they readily rooted, and after transfer to soil, developed into normal, fertile plants. Unlike their tobacco parental line, BarD, the obtained plants are resistant to kanamycin [they root normally in the presence of kanamycin (200 mg/1)] and possess activity of neomycin phosphotransferase (NPT II) with the same electrophoretic mobility as the one of the nightshade line. According to Southern blot hybridization analysis carried out with the use of radioactively labeled cloned fragments of the Citrus lemon ribosomal DNA repeat, as well as with Nicotiana plumbaginifolia genus-specific, interspersed repeat Inp, the kanamycin-resistant plants under investigation have only species-specific hybridizing bands from tobacco. Cytological analysis of the chromosome sets shows that plants of all three lines possess 48 large chromosomes similar to Nicotiana tabacum ones (2n = 48), and one small extra chromosome (chromosome fragment) similar to Atropa belladonna ones (2n = 72). Available data allow the conclusion that highly asymmetric, normal fertile somatic hybrids with a whole diploid Nicotiana tabacum genome and only part (not more than 2.8%) of an Atropa belladonna genome have been obtained without any pretreatment of a donor genome, although both these species are somatically congruent.
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    URL: http://dx.doi.org/10.1007/BF00223985
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    Impact of the stringency of cell selection on plastid segregation in protoplast fusion-derived Nicotiana regenerates (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 866-873 
    Details
    ISSN: 1432-2242
    Keywords: Nicotiana ; Plastid genetic markers ; Plastid segregation ; Plastid selection ; Protoplast fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Vegetative segregation of a mixed plastid population in protoplast fusion-derived cell lines can be directed by a selection favouring the multiplication of one of the parental plastid types. This report defines some of the critical conditions leading to a homogeneous plastid population in cybrid plants generated by protoplast fusion between Nicotiana plumbaginifolia and an albino and streptomycin-resistant N. tabacum plastid mutant. Light (1,500 lx) conferred a strong selective advantage to chloroplasts versus albino plastids, while the lack of this effect in dim light (300 lx) indicated that a sufficient light intensity is essential to the phenomenon. Selection on streptomycin-containing medium in the dark, however, led to the preferential multiplication of resistant plastids. Streptomycin selection of resistant chloroplasts in the light, consequently, results in a plastid selection of doubled stringency. In another experiment a definite, but leaky, selection for chloroplast recombination (selection for greening on streptomycin-containing medium in dim light) was used to reveal various recombination products. Protoplast fusion in fact resulted in cybrid plants showing only simple chimeric segregation of unchanged parental plastids. These results demonstrate the essential requirement for stringent plastid selection, as defined by cell culture conditions, to precede the formation of shoots expected to possess the desired plastid genetic composition.
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    URL: http://dx.doi.org/10.1007/BF00227398
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    Restoration of fertility in cytoplasmic male sterile (CMS) Nicotiana Sylvestris by fusion with X-irradiated N. tabacum protoplasts (1980)
    Springer
    Theoretical and applied genetics 58 (1980), S. 121-127 
    Details
    ISSN: 1432-2242
    Keywords: Nicotiana ; Cytoplasmic-male-sterility ; Somatic hybridization ; Plastid segregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restoration of male fertility was achieved by fusing protoplasts from male sterile (CMS) Nicotiana sylvestris plants with X-irradiated protoplasts derived from fertile N. tabacum plants. The CMS N. sylvestris plants were derived from a previous somatic hybridization experiment and contained alien (Line 92) cytoplasm. About one quarter of the regenerated plants were found to be cybrids. i.e. they consisted of N. sylvestris nuclei combined with all or some components of N. tabacum cytoplasm. In one half of these cybrids male fertility was restored to different levels. The chloroplasts of the two parental donors differ in respect to tentoxin sensitivity: chloroplasts of CMS N. sylvestris are sensitive while those of N. tabacum are insensitive. It could therefore be demonstrated that there was an independent segregation of chloroplast type and male fertility/sterility: several somatic cybrids were male fertile but tentoxin sensitive and others were tentoxin insensitive yet they were male sterile. Only in about one half of the somatic cybrids was male fertility restored together with restoration to tentoxin insensitivity.
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    URL: http://dx.doi.org/10.1007/BF00263102
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    The gene for the α-subunit of ATPase: a site of homologous recombination in plant mitochondrial DNA also functions in somatic hybrid cells (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 33-38 
    Details
    ISSN: 1432-2242
    Keywords: Homologous recombination ; ATPase α-subunit ; Protoplast fusion ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Segments of mitochondrial DNA (mtDNA) carrying the gene for the α-subunit of F1-ATPase (atpA) were detected by Southern hybridization with atpA from pea as probe. In the case of Nicotiana langsdorffii, we identified four fragments that are derived from combinations of two different 5′ and two different 3′ flanking regions of atpA. All four types share the coding region, suggesting that they result from homologous recombination in the coding region of atpA. By contrast, N. glauca generated only one analogous fragment, which indicated the existence of only a single type of atpA in N. glauca. In the case of somatic hybrids obtained by fusion between protoplasts from N. langsdorffii and N. glauca, analysis with EcoRI or HindIII detected three new fragments in addition to the parental fragments. These new fragments can be explained by homologous recombination within the coding region of atpA. Our results show that the coding region of atpA is involved not only in intragenomic homologous recombination but can also be involved in homologous recombination between two parental mitochondrial genomes of somatic hybrids.
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    URL: http://dx.doi.org/10.1007/BF00223978
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    Vasopressin- and oxytocin-containing fibres in the pineal gland and subcommissural organ of the rat (1980)
    Springer
    Cell & tissue research 205 (1980), S. 11-17 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Subcommissural organ ; Vasopressin ; Oxytocin ; Vasotocin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vasopressin and oxytocin were specifically demonstrated in the rat brain using the unlabelled antibody-enzyme method and purification of the first antiserum. Vasopressin and oxytocin fibres extend via the subcommissural organ or habenular commissure into the pineal stalk and terminate in the anterior part of the pineal organ. In addition, immediately adjacent to the subsommissural organ many vasopressin-containing fibres run caudally toward the central grey. These results are discussed in relation to the proposed presence of vasotocin in the pineal gland.
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    URL: http://dx.doi.org/10.1007/BF00234438
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    VIP (Vasoactive Intestinal Polypeptide)-immunoreactive neurons in the retina of the rat (1980)
    Springer
    Cell & tissue research 210 (1980), S. 167-170 
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    ISSN: 1432-0878
    Keywords: Neuropeptides ; VIP-immunoreactive neurons ; Retina ; Amacrine cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunoreactive vasoactive intestinal polypeptide (VIP) was detected in a population of amacrine cells in the retina of the rat. Processes of these cells reach both the inner and outer half of the inner plexiform layer where they form sublayers. The VIP neurons are different from previously known amacrine cell types.
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    URL: http://dx.doi.org/10.1007/BF00232152
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    Simultaneous monoamine histofluorescence and neuropeptide immunocytochemistry (1980)
    Springer
    Cell & tissue research 210 (1980), S. 181-189 
    Details
    ISSN: 1432-0878
    Keywords: Catecholamines ; Neurophysin ; Simultaneous demonstration ; Functional interaction ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A method was developed that allows the analysis of neuropeptides and monoamines in a single tissue section by the application of the unlabeled antibody method for peptide staining to tissue sections freeze-dried for formaldehyde-induced monoamine histofluorescence. The hypothalamic magnocellular system of male albino rats served as a model for this study; neurons were stained with anti-neurophysin sera, which mark the vasopressin- and oxytocin-associated proteins. Neurophysin-containing perikarya appeared to be surrounded by catecholamine-containing varicosities. This phenomenon was seen to varying degrees within the supraoptic and paraventricular nuclei. The juxtaposition of varicosities and peptidergic neurons suggests an afferent fiber-target neuron relationship that might favor a functional interaction between monoamines and neuropeptides.
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    URL: http://dx.doi.org/10.1007/BF00237608
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    Ultrastructural alterations associated with the initiation of follicular atresia (1980)
    Springer
    Cell & tissue research 211 (1980), S. 105-115 
    Details
    ISSN: 1432-0878
    Keywords: Rat ; Preovulatory follicle ; Ultrastructure ; Degeneration ; Atresia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To identify and describe ovarian follicles committed to undergo follicular degeneration (atresia), immature rats were primed with pregnant mare serum gonadotropin (PMSG). After PMSG treatment, preovulatory follicles develop but subsequently degenerate. Prior to the appearance of pyknotic nuclei (Stage I of atresia), degenerative changes were observed in focal areas of the granulosa cell layer. These changes include “blebbing” of the cytoplasm and alterations in the shape of the granulosa cells. The appearance of these degenerative changes coincides with a decrease in ovarian concentrations of estradiol and testosterone. Since estrogens and androgens maintain the follicle, the decline in estradiol and testosterone could be responsible for the further degenerative alterations that lead to complete deterioration of the preovulatory follicle. In Stage I atretic follicles, lysosome-derived autophagic vacuoles develop and macrophages invade both the thecal and granulosa cell layers. The combined actions of the autophagic vacuoles and macrophages could destroy both the granulosa-cell and thecal layers and thereby transform the preovulatory follicle into an ovarian cyst.
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    Depletion of macrophages and disappearance of postcapillary high endothelial venules in lymph nodes deprived of afferent lymphatic vessels (1980)
    Springer
    Cell & tissue research 211 (1980), S. 375-389 
    Details
    ISSN: 1432-0878
    Keywords: Lymph node ; Macrophages ; Postcapillary high endothelial venules ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The afferent lymphatic vessels of rat popliteal lymph nodes were interrupted, and the histological alterations in the lymph nodes occurring 1 to 14 weeks after operation were studied. One week after operation the number of macrophages was considerably reduced and continued to decrease during the subsequent time periods studied. A 6 weeks most macrophages had disappeared. Simultaneously the immunological activity diminished and had completely disappeared 8 weeks after operation. Three weeks after operation the endothelial cells of the postcapillary high endothelial venules had flattened, and the number of immigrating lymphocytes was greatly reduced. Subsequently the lymph nodes became depleted of both macrophages and lymphocytes, leaving only the reticuloendothelial framework.
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    A scanning electron microscope study of myoepithelial cells in exocrine glands (1980)
    Springer
    Cell & tissue research 209 (1980), S. 1-10 
    Details
    ISSN: 1432-0878
    Keywords: Myoepithelial cell ; Exocrine gland ; Scanning electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By removing connective tissue components with enzymatic digestion followed by HCl-hydrolysis, myoepithelial cells (MECs) of the terminal portion in a variety of exocrine glands of the rat were examined with the scanning electron microscope. The profile of MECs varied considerably from gland to gland; MECs in the lactating mammary gland have a few long cytoplasmic processes in close contact with those of adjacent cells forming a continuous network around the terminal portion. Those of the exorbital lacrimal gland are stellate with many thin radiating processes with tapered ends that terminate freely. MECs in the sublingual gland are characterized by a number of broad and extensive cellular processes. MECs in the submandibular gland are similar in appearance to those of the exorbital lacrimal gland, but with more extensive cellular processes that form a more or less continuous network with those of the adjacent cells. No MECs were observed on the terminal portion of the parotid gland where the cells appear to be lodged on the intercalated duct. The relative surface area covered by MECs per terminal portion was also found to vary significantly, being 24% in the lactating mammary, 17% in the exorbital lacrimal, 48% in the sublingual, and 25% in the submandibular glands. The findings are discussed in relation to the physical properties of secretions in different glands.
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    URL: http://dx.doi.org/10.1007/BF00219918
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    Nongranular vasopressin synthesis and transport in early stages of rehydration (1980)
    Springer
    Cell & tissue research 207 (1980), S. 89-107 
    Details
    ISSN: 1432-0878
    Keywords: Rehydration ; Nongranular vasopressin ; Intercellular clefts ; Axoplasmic reticulum ; Ultrastructural immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The vasopressin system of the rat was examined in the course of the first 12 h of rehydration after prolonged thirst at light and electron microscopic levels and by use of the peroxidase anti-peroxidase (PAP) method. Light microscopically, the median eminence was the only part of the system that not only displayed distinct differences between animals of different rehydration times but also showed a characteristic pattern of immunohistochemical reactivity in its rostro-caudal distribution. Ultrastructurally, in the perikarya a maximal labeling of the rough endoplasmic reticulum was observed after 2 h of rehydration, whereas an extensive labeling of the enlarged Golgi zones was attained after 4 h of resupplying water. A labeling of the intercellular clefts in the basal glial labyrinth of the supraoptic nucleus (and to a lesser degree in the subependymal neuropil adjacent to the paraventricular nucleus) was increased 30 min after the onset of drinking, as compared with water-deprived animals; it decreased slightly after 12 h of rehydration. The filling of the swollen fibers by increasing amounts of labeled axoplasmic reticulum, evident in the nuclear areas already after 30 min of water supply, begins in the median eminence after 2 h of rehydration and is fully developed after 4 and 8 h. Corresponding results hold true for the neural lobe but are somewhat delayed in comparison to the findings in the median eminence. The discussion considers (i) synthesis and transport of nongranular vasopressin within the axoplasmic reticulum, and (ii) release not only from the neural lobe but also from the nuclear areas and from the fibers of the median eminence.
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    Receptor-mediated and adsorptive endocytosis by male germ cells of different mammalian species (1992)
    Springer
    Cell & tissue research 268 (1992), S. 471-478 
    Details
    ISSN: 1432-0878
    Keywords: Testis ; Endocytosis ; Spermatogenesis ; Spermatogonia ; Spermatocytes ; Spermatids ; Transferrin ; Ferritin ; Sertoli cells ; Mouse ; Rat ; Monkey, Macaca fascicularis (Primates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The routes for adsorptive and receptor-mediated endocytosis were studied in vivo after microinjection of tracers into the lumen of the seminiferous tubules, and in vitro in isolated germ cells of different mammals. Cationic ferritin was located on the plasma membrane, in vesicles, in tubules, in multivesicular bodies and in lysosome-like granules of mouse spermatocytes. In these cells the number of multivesicular bodies varied during spermatogenesis. Spermatids and to a lesser extent residual bodies also performed adsorptive endocytosis. In the rat and monkey (Macaca fascicularis) diferric transferrin was specifically taken up by germ cells via receptor-mediated endocytosis. The labelling was observed subsequently in membrane pits, vesicles, endosome-like bodies and pale multivesicular bodies. A progressive decrease in the frequency of the labelling of the germ cells by transferrin-gold particles was observed from spermatogonia to spermatocytes and to early spermatids, which could indicate that iron is particularly required by germ cells during the mitotic and meiotic processes. Adsorptive and receptor-mediated endocytosis therefore occurs in all classes of germ cells. These endocytic processes are most probably required for germ cell division, differentiation and metabolism.
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    Functional reinnervation of the neostriatum in the adult rat by use of intraparenchymal grafting of dissociated cell suspensions from the substantia nigra (1980)
    Springer
    Cell & tissue research 212 (1980), S. 39-45 
    Details
    ISSN: 1432-0878
    Keywords: Neuronal grafting ; Dopamine ; Nigrostriatal system ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Dissociated cell suspensions were prepared from the substantia nigra of 15–17 day-old rat embryos and grafted via an intraparenchymal injection into the depth of the neostriatum of adult recipient rats. The survival and fibre outgrowth of the dopamine-containing neurones in the implants were studied by fluorescence histochemistry, and the functional capacity of the grafts was monitored by repeated testing of the amphetamine-induced turning behaviour of the implanted rats. Before transplantation the target neostriatum of the recipient rats was denervated of its normal dopaminergic innervation by an injection of 6-hydroxydopamine into the ipsilateral nigrostriatal dopamine pathway. The completeness of the denervation was ascertained by measurement of the intensity of the amphetamine-induced turning response. After injection of the dissociated cells large numbers of dopamine-containing neurones were found in clusters at the site of injection as well as scattered in the apparently intact neostriatal tissue up to a distance of about 0.5 mm from the site of injection. Extensive dopamine-containing fibre networks had developed around the implant. These newly formed fibres, which were most abundant around the cell clusters at the injection site, extended in a loose network into large areas of the initially denervated caudate-putamen. In all animals with surviving dopamine neurones the amphetamine-induced turning response was reduced, and in the most extensively reinnervated cases even reversed, within 3–5 weeks after transplantation. This strongly suggests that the implanted dopamine neurones are capable of restoring dopaminergic neurotransmission in the denervated neostriatum, probably via reinnervation of the denervated neostriatal tissue. The use of dissociated brain tissue preparations thus permits reliable intraparenchymal grafting of neurones to plausibly any desired site within the central nervous system, and should open entirely new possibilities for investigation of neuronal growth dynamics and functional reconstruction of damaged brain circuits, perhaps even in brains of larger mammals.
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    A peculiar fibrillar pattern in the myocardial cells of trabeculae carneae in the right ventricle of the rat, mouse, and rabbit (1980)
    Springer
    Cell & tissue research 208 (1980), S. 165-168 
    Details
    ISSN: 1432-0878
    Keywords: Cardiac muscle cells ; Trabeculae carneae ; Fibrillar pattern ; Mouse ; Rat ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cardiac muscle fibers in the trabeculae carneae of mice, rats, and rabbits show a special arrangement of densely interwoven myofibrils. They cross at various angles; however, a preferred orientation of the fibrils cannot be discerned. It is suggested that due to this arrangement the myocytes of trabeculae are not able to contract to the same extent as ventricular myocytes, but thereby gain a high rigidity during contraction. Hence, they may play a principal role as “guiding ridges” for the flow of blood, thereby improving hemodynamics.
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    The influence of high pressure freezing on mammalian nerve tissue (1980)
    Springer
    Cell & tissue research 209 (1980), S. 201-216 
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    ISSN: 1432-0878
    Keywords: High pressure (2,100 bars) freezing ; Freeze-etching ; Nerve tissue ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vitrification of biological specimens in liquid nitrogen can be achieved under high pressure (2,100 bars). This procedure obviates the use of aldehyde fixation and cryoprotection (glycerol). The present work demonstrates its applicability to the freeze-etching of mammalian brain tissue. Freeze-fracture replicas from rat cerebellar cortex and subfornical organ prepared by this method are compared to conventionally processed material using aldehyde fixation, glycerination and freezing with Freon. The formation of large ice crystals is prevented in tissue blocks up to 0.5 mm thick; deep etching is markedly enhanced. Cytoplasmic microstructures such as mitochondrial cristae, microtubules and microfilaments, are readily observable against a finely granulated cytosol matrix. An additional advantage is the combined application with freeze-substitution.
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    The structure of cleft material in spine synapses of rat cerebral and cerebellar cortices (1980)
    Springer
    Cell & tissue research 206 (1980), S. 477-486 
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    ISSN: 1432-0878
    Keywords: Synapse ; Synaptic cleft ; Aldehyde ; PTA technique ; Densitometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptic clefts of rat cerebral and cerebellar axodendritic spine synapses were studied after aldehyde-perfusion and subsequent immersion into osmic acid or after processing by the aldehyde-PTA technique. The threedimensional examination of aldehyde-perfused, osmic acid postfixed synapses revealed a double-layered intracleft lamina comparable in dimensions and position to the cleft density of non-osmicated, PTA-stained synapses. The relationship of this lamina to perisynaptic astroglial processes was pointed out. Densitometric analysis of the cleft area suggested the identity of the intracleft lamina of osmicated synapses with the cleft density of non-osmicated, PTA-stained synapses.
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    URL: http://dx.doi.org/10.1007/BF00237976
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    Studies on the juxtaglomerular apparatus VI. Sympathetic innervation, catecholamines and the renin-angiotensin-system in rats and tree-shrews (Tupaia belangeri) (1980)
    Springer
    Cell & tissue research 212 (1980), S. 375-382 
    Details
    ISSN: 1432-0878
    Keywords: Juxtaglomerular apparatus ; Sympathetic innervation ; Renin-angiotensin system ; Electron microscopy ; Fluorescence microscopy ; Tupaia belangeri ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It has previously been reported that the primitive primate Tupaia belangeri develops a renal failure when exposed to psychosocial stress. In order to learn if this high susceptibility to stress of the Tupaia kidney can be correlated with morphological and functional parameters of the Juxtaglomerular apparatus (JGA) and the renin-angiotensin system, comparative experiments were performed on Tupaia and rat. Our results reveal an outstandingly high potency of the JGA and the renin-angiotensin system in Tupaia as evident from the following findings: The Tupaia JGA contains a great number of epithelioid cells abounding in renin granules (electron microscopy). The renin content of the Tupaia kidney is considerably higher than in the rat (radio-immunoassay). The sympathetic innervation of the kidney and especially of the JGA is abundant in Tupaia (fluorescence and electron microscopy). Catecholamine contents of the kidney and other organs are significantly higher in Tupaia than in rats (spectrophotofluorometry). Our results support the previously developed concept of a potent intrarenal neuroendocrine interaction at the JGA level favouring, under certain conditions of social stress, the development of acute renal failure in Tupaia belangeri.
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    URL: http://dx.doi.org/10.1007/BF00236504
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    Ultrastructural alterations in the initial segments and in the recurrent collateral terminals of Purkinje cells following axotomy (1980)
    Springer
    Cell & tissue research 212 (1980), S. 415-427 
    Details
    ISSN: 1432-0878
    Keywords: Cerebellum ; Purkinje axon ; Ultrastructure ; Axotomy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transection of Purkinje cell axons in adult male rats made 1.5 mm or further from the cell body does not lead to the death of the neuron and results in compensatory structural alterations of the surviving axonal portions of the nerve cell. Near to, and at the emergence of recurrent collaterals of Purkinje cell axons, huge varicosities filled with filaments, granular material, lysosomes and mitochondria develop. Terminals of recurrent axon collaterals also exhibit different degrees of structural changes. Most striking of the morphological alterations is the regular presence of nematosomes in the hypertrophic axonal branches, especially in synaptic terminals. Since nematosomes were shown to contain RNA in other types of neurons, their presence in recurrent collaterals may indicate an enhanced synthetic activity in Purkinje axonal processes and endings after axotomy.
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    URL: http://dx.doi.org/10.1007/BF00236507
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    Interlamellar tight junctions of central myelin (1980)
    Springer
    Cell & tissue research 213 (1980), S. 81-94 
    Details
    ISSN: 1432-0878
    Keywords: Interlamellar tight junctions ; Central myelin ; Myelogenesis ; Optic nerve ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The process of myelination in the central nervous system (CNS) of the rat (optic nerve) was studied with the freeze-fracturing technique and ultrathin sectioning to obtain information on the developmental mechanisms of interlamellar tight junctions. Using a tilting cartridge for analysis of thin sections, it could be demonstrated that during the initial phase of wrapping a tight junction formation develops between the joining tips of the oligodendrocytic process. In tannic acid-stained samples these junctions appear as typical quintuple-layered membrane fusions, while in potassium permanganate-stained material membrane thickenings between the apposing glial tips are prevalent. The latter configuration represents the characteristic feature of the so-called radial component of central myelin. Using the freeze-fracturing technique, a biphasic mode of the myelinic tight junction assembly was detected. It is suggested that tight junctions represent a prerequisite of the myelination process.
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    URL: http://dx.doi.org/10.1007/BF00236922
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    Relation between growth conditions and dormancy of seed potatoes. 1. Effects of nitrogen (1992)
    Springer
    Potato research 35 (1992), S. 355-364 
    Details
    ISSN: 1871-4528
    Keywords: cultivar ; nitrate ; nitrogen ; Solanum tuberosum L. ; tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The duration of dormancy of seed potatoes varies between years and between origins. Therefore, the effects of conditions during crop growth on dormancy of progeny tubers were studied. The effect of nitrogen during tuber bulking on the duration of dormancy was investigated in three field experiments with two cultivars. In addition to an application of 125 kg N/ha at planting, top dressings of 0–150 kg N/ha were given about 2 weeks after tuber initiation. Haulm was pulled about 4 weeks later. The effect of nitrogen rate at planting was also examined in one experiment. Nitrogen top dressings shortened dormancy in all experiments by 5–8 days. An increased nitrogen rate at planting resulted in a shorter dormancy when the duration of dormancy was expressed in days after tuber initiation, but not when it was expressed in days after haulm pulling, probably because extra nitrogen also delayed tuber initiation.
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    URL: http://dx.doi.org/10.1007/BF02357592
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    Relation between growth conditions and dormancy of seed potatoes. 2. Effects of temperature (1992)
    Springer
    Potato research 35 (1992), S. 365-375 
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    ISSN: 1871-4528
    Keywords: cultivar ; heat sprouting ; nitrogen ; second growth ; Solanum tuberosum L. ; sprout ; tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In two indoor experiments under short day conditions, the effect of temperature during tuber bulking on dormancy of tubers was investigated for cvs Diamant and Désirée. Temperature treatments started after tuber initiation and lasted for 4 weeks, after which the haulm was removed. In Experiment 1, the day/night temperature regimes 18/12, 22/22, 26/18 and 32/12 °C (T18/12 etc.) were compared. In Experiment 2, three day temperatures (18, 24 and 30 °C) were combined with three night temperatures (12, 18 and 24 °C), resulting in nine treatments. The dormancy of cv. Diamant was shortest after very high day temperatures (30–32 °C), but intermediate day temperatures (22–26 °C) had no shortening effect compared to T18/12. Dormancy of cv. Désirée was not shortened, but rather tended to be prolonged by high temperatures (22–32 °C) during growth. High temperatures during growth resulted in more sprouts per tuber after dormancy had ended.
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    URL: http://dx.doi.org/10.1007/BF02357593
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    Dry matter content and mineral composition of potatoes grown in Cyprus (1980)
    Springer
    Potato research 23 (1980), S. 371-375 
    Details
    ISSN: 1871-4528
    Keywords: nitrogen ; phosphorus ; potassium ; calcium ; sodium ; nitrate ; sulphate ; micronutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The specific gravity and dry matter content of 193 tuber samples (cultivars: Arran Banner, Spunta, Up-to-Date, Cara) from crops grown at Kokkinochoria, the major potato growing area of Cyprus, were related to each other as follows: Dry matter (%)=−269.59+268.24×specific gravity. This regression accounted for 82.4% of the variation; the fiducial limits (P〈0.05) for single determinations of specific gravity were±1.54 percentage units. The mineral contents of the tubers were similar to those reported in other countries.
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    URL: http://dx.doi.org/10.1007/BF02360677
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    An EPR and molecular mechanics study of radical adducts of phosphonyl radicals with 2-hydroperfluoro-4-methyl-and 4,4-dimethyl-2-pentene (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 2008-2011 
    Details
    ISSN: 1573-9171
    Keywords: EPR ; radical ; fluorine ; conformation ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract EPR spectra of radical adducts of phosphonyl radicals with 2-hydroperfluoro-4-methyl- and 4,4-dimethyl-2-pentene have been studied. The molecular mechanics method has been used to determine the preferred conformation of the (CF3)2CF-CF-HCF3P(O)(OMe)2 radical. The eclipsed conformation of the C–P bond and 2p z -orbital of an unpaired electron is stabilized due to steric factor and hyperconjugation.
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    URL: http://dx.doi.org/10.1007/BF00863364
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    Sperm cells in pollen tubes ofNicotians tabacum L.: three-dimensional reconstruction, cytoplasmic diminution, and quantitative cytology (1992)
    Springer
    Protoplasma 168 (1992), S. 172-183 
    Details
    ISSN: 1615-6102
    Keywords: Cytoplasmic inheritance ; Male cytoplasmic diminution ; Male gamete (angiosperm) ; Male germ unit ; Nicotiana ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of the sperm cells and vegetative nucleus (male germ unit) ofNicotiana tabacum was examined 18 h after semivivo pollination using transmission electron microscopy, computerassisted serial section reconstruction and quantitative cytology. Based on a measurement of 11 cellular parameters in nine reconstructed sperm cell pairs, there are no statistically significant differences between the two cells. The Svn is characterized by a strapshaped cytoplasmic extension that is physically associated with the surface of the vegetative nucleus. The nucleus is located adjacent to the sperm crosswall, with sperm organelles being distributed between the nucleus and the extension. The Sua is a tapered cell with cytoplasmic areas at both poles and deep axial invaginations near the crosswall. This cell has a centrally-located nucleus and a largely polar distribution of organelles. Three mechanisms for cytoplasmic diminution were observed that appear to contribute actively to the loss of cytoplasmic volume and organelles: (1) enucleated cytoplasmic body production in the Sua; (2) vesiculation at the tip of the cytoplasmic projection of the Svn; and (3) vesicle-containing body accumulation in the periplasm of both the Svn and Sua.
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    URL: http://dx.doi.org/10.1007/BF01666263
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    Selection of embryogenic pollen from cold-treated buds ofNicotiana tabacum var. badischer burley and their development into embryos in cultures (1980)
    Springer
    Protoplasma 105 (1980), S. 161-167 
    Details
    ISSN: 1615-6102
    Keywords: Embryogenic pollen ; Nicotiana ; Pollen culture ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary By using density gradient centrifugation, employing 55% percoll and 4% sucrose as suspension medium, it is possible to select embryogenic pollen from buds after cold treatment at 10 °C for 8 or more days. These buds at the uninucleate stage of pollen were collected from plants grown in 8 hours photocycles at 18 °C and supplied with mineral salts. The embryogenic pollen are small, starch-free with a clear cytoplasm whereas large starch-filled ones are nonembryogenic. The embryogenic pollen regularly form embryos at a frequency of 2% on a mineral medium supplemented with glutamine, asparagine and sucrose at pH 6.5. These results demonstrate, for the first time, that it is possible to have embryos in appreciable frequencies in “ab initio” pollen cultures raised from cold treated anthers.
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    URL: http://dx.doi.org/10.1007/BF01279858
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    Changes in fatty acids, amino acids and carbon/nitrogen biomass during nitrogen starvation of ammonium- and nitrate-grownIsochrysis galbana (1992)
    Springer
    Journal of applied phycology 4 (1992), S. 95-104 
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    ISSN: 1573-5176
    Keywords: amino acids ; biomass ; fatty acids ; Isochrysis ; nitrogen ; starvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth of cells ofIsochrysis galbana with either nitrate or ammonium as the N-source, and the effects of subsequent N-starvation of these cells, were compared. During exponential N-sufficient growth nitrate-grown cells had double the fatty acid content of the ammonium-grown cells but lower concentrations of a few amino acids. Following resuspension in N-free medium the fatty acid content of the ammonium-grown cells increased to that of the nitrate-grown cells, but there was no further increase in fatty acid content on a C-biomass or cellular basis during the following 4 days for either culture. Fatty acid synthesis was continuous during N-starvation, while it occurred during the light-phase only in exponential growth. The proportion of 18:1n9 fatty acid increased from 10 to 25% total fatty acids during N-starvation. Intracellular free amino acid content decreased in a similar manner in both cultures on N-starvation, the ratio of intracellular free amino-N/cell-C falling more rapidly than overall cellular N/C. It was concluded that optimal amino acid and fatty acid content would be attained by growth in the presence of excess nitrate. Measurements of chlorophyll and carotenoid content and ofin vivo fluorescence indicated that these parameters had potential for monitoring the C and N biomass in cultures grown under relatively constant (not necessarily continuous) illumination.
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    URL: http://dx.doi.org/10.1007/BF02442457
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    Growth and mineral nutrition of six rapid-cycling Brassica species in response to seawater salinity (1992)
    Springer
    Plant and soil 139 (1992), S. 285-294 
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    ISSN: 1573-5036
    Keywords: Brassica ; B. campestris ; B. carinata ; B. juncea ; B. naptus ; B. nigra ; B. oleracea ; calcium ; chloride ; potassium ; magnesium ; nitrogen ; sodium ; nutrients ; salinity ; salt-tolerance ; seawater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The growth of six rapid-cycling lines of Brassica species, B. napus, B. campestris, B. nigra, B. juncea, B. oleracea and B. carinata was inhibited by seawater salinity. Based on the change in dry matter reduction relative to the control at varying concentrations of salts (4, 8 and 12 dS m-1), the relative salt tolerance of these species was evaluated. B. napus and B. carinata were the most tolerant and most sensitive species, respectively, while the other four species were moderately tolerant. The influence of seawater on the concentrations of 12 elements including macronutrients and micronutrients in the shoots of these Brassica plants was characterized to determine the relationship between nutritional disturbance and relative salt tolerance. It was found that seawater salinity had a significant effect on the concentrations of Ca, Mg, K, Cl, Na and total N in the shoots of these plants but only the change in Ca concentration was significantly related to the relative salt tolerance of these six rapid-cycling Brassica species according to a rank analysis of the data. This finding indicates that Ca may play a regulatory role in the responses of Brassica species to saline conditions.
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    URL: http://dx.doi.org/10.1007/BF00009320
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    Nitrogen and phosphorus cycling in relation to stand age of Ecucalyptus regnans F. Muell (1992)
    Springer
    Plant and soil 142 (1992), S. 157-166 
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    ISSN: 1573-5036
    Keywords: Acacia ; Eucalyptus regnans ; decomposition ; litterfall ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The N and P contents of the litter layer and the return of these nutrients in litterfall were measured in seven stands of Mountain Ash (Eucalyptus regnans) ranging in age from 5 years to about 250 years. Both annual litterfall and nutrient return were correlated with stand basal area and were high compared with other productive eucalypt forests. In contrast, the fall of dead eucalypt leaves was constant with stand age, demonstrating that sites are fully occupied at an early age. Similarly, amounts of N and P in total leaf fall (overstorey plus understorey) were constant with stand age, except for low amounts in the stand aged 40 years where Acacia spp., important fixers of atmospheric N, were not prevalent. The decomposition constant (k) of organic matter in the litter layer decreased with stand age, from 0.31 year-1 at age 5 years to 0.23 year-1 at age 250 years. These constants also applied to N and P, indicating a tight coupling between organic matter decomposition and release of these nutrients from litter. The litter layer released about 30 kg ha-1 of N at age 5 years, and about 70 kg ha-1 at age 80 years. These results are discussed in relation to growth of Mountain Ash following fire, and the subsequent retention and accumulation of N during stand development.
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    Nitrogen and phosphorus cycling in relation to stand age of Eucalypus regnans F. Muell. (1992)
    Springer
    Plant and soil 142 (1992), S. 167-176 
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    ISSN: 1573-5036
    Keywords: Eucalyptus regnans ; mineralization ; nitrification ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory and in situ rates of N mineralization in soils from Mountain Ash (Eucalyptus regnans) forests were measured fortnightly for two years in stands aged 9, 40, 80 and about 250 years (overmature), and for one year in stands aged 5 and 46 years. Rates of anaerobic mineralization (the laboratory test) showed little seasonal or annual variation. In contrast, rates of in situ mineralization varied markedly with season, being highest in spring and summer. Anaerobic mineralization was highly correlated with stand age to 80 years, but decreased between ages 80 and 250 years. In situ mineralization also decreased between these two ages, but otherwise was not related to stand age. Hence, the correlation between anaerobic and in situ mineralization along the age sequence was weak, suggesting that the anaerobic test is of maximum utility when this pool is in balance with inputs from decomposing litter (‘steady-state’ ecosystems). Nitrification was strong in stands aged 9, 46, 80 and 250 years and weak in stands aged 5 and 40 years. Within stands, the rate of nitrification during each period of in situ containment was highly dependent on the supply of NH4 ions. Between stands, annual rates of nitrification appear to be related to the balance between the N capital of the site, its rate of turnover, and the demand for N by heterotrophs and vegetation so that if NH4 supply is depleted, little is left for autotrophic nitrifiers.
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    Soil phosphorus status, pH and the manganese nutrition of wheat (1992)
    Springer
    Plant and soil 145 (1992), S. 45-50 
    Details
    ISSN: 1573-5036
    Keywords: acidity ; manganese ; pH ; phosphorus ; soil solution wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A pot experiment was carried out in order to test the hypothesis that manganese nutrition of wheat was dependent on the phosphorus status of soil as well as on its pH and manganese status. An arable mineral soil whose lime and phosphorus status had been massively adjusted more than 18 years previously was compared with identical soil not so adjusted. Wheat plants were grown to maturity in these soils. Analyses were carried out on both soil and plant samples at intervals. Data for soil pH, soil solution concentrations of manganese and phosphorus, plant dry weight and tissue concentrations of manganese and phosphorus are presented. Concentrations of manganese were depressed in leaf tissue of plants from limed soils and also in high phosphorus soils. The depressed values for limed treatments were explained in terms of depressed soil solution manganese concentrations resulting from elevated pH. The results for high phosphorus soils could not be related to soil solution composition. It was suggested that high soil phosphorus resulted in elevated plant phosphorus which interfered in the uptake and/or translocation of manganese.
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    A review of phosphorus efficiency in wheat (1992)
    Springer
    Plant and soil 146 (1992), S. 163-168 
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    ISSN: 1573-5036
    Keywords: genetic variability ; NIR ; ploidy ; phosphorus ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract More efficient utilization of phosphorus by wheat plants is needed to extend the useful life of the phosphate reserves in the world, to reduce the cost of producing crops, and to improve the value of the grain and the straw produced. In this paper definitions of efficient use of phosphorus by wheat are reviewed, genotypic variation in phosphorus efficiency is reported, some consequences of breeding for greater efficiency are discussed, and ways to select more efficient genotypes are suggested.
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    The influence of nitrogen concentration and ammonium/nitrate ratio on N-uptake, mineral composition and yield of citrus (1992)
    Springer
    Plant and soil 147 (1992), S. 13-23 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; citrus ; nitrate ; NO3 −/NH4 + ratio ; nitrogen ; nutrient solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In short-term water culture experiments with different 15N labeled ammonium or nitrate concentrations, citrus seedlings absorbed NH4 + at a higher rate than NO3 −. Maximum NO3 − uptake by the whole plant occurred at 120 mg L−1 NO3 −-N, whereas NH4 + absorption was saturated at 240 mg L−1 NH4 +-N. 15NH4 + accumulated in roots and to a lesser degree in both leaves and stems. However, 15NO3 − was mostly partitioned between leaves and roots. Adding increasing amounts of unlabeled NH4 + (15–60 mg L−1 N) to nutrient solutions containing 120 mg L−1 N as 15N labeled nitrate reduced 15NO3 − uptake. Maximum inhibition of 15NO3 − uptake was about 55% at 2.14 mM NH4 + (30 mg L−1 NH4 +-N) and it did not increase any further at higher NH4 + proportions. In a long-term experiment, the effects of concentration and source of added N (NO3 − or NH4 +) on nutrient concentrations in leaves from plants grown in sand were evaluated. Leaf concentration of N, P, Mg, Fe and Cu were increased by NH4 + versus NO3 − nutrition, whereas the reverse was true for Ca, K, Zn and Mn. The effects of different NO3 −-N:NH4 +-N ratios (100:0, 75:25, 50:50, 25:75 and 0:100) at 120 mg L−1 total N on leaf nutrient concentrations, fruit yield and fruit characteristics were investigated in another long-term experiment with plants grown in sand cultures. Nitrogen concentrations in leaves were highest when plants were provided with either NO3 − or NH4 + as a sole source of N. Lowest N concentration in leaves was found with a 75:25 NO3 −-N/NH4 +-N ratio. With increasing proportions of NH4 + in the N supply, leaf nutrients such as P, Mg, Fe and Cu increased, whereas Ca, K, Mn and Zn decreased. Yield in number of fruits per tree was increased significantly by supplying all N as NH4 +, although fruit weight was reduced. The number of fruits per tree was lowest with the 75:25 NO3 −-N:NH4 +-N ratio, but in this treatment fruits reached their highest weight. Rind thickness, juice acidity, and colour index of fruits decreased with increasing NH4 + in the N supply, whereas the % pulp and maturity index increased. Percent of juice in fruits and total soluble solids were only slightly affected by NO3 −:NH4 + ratio.
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    Carbohydrate and nitrogen sources affect respectively in vitro germination of immature ovules and early seedling growth of Impatiens platypetala Lindl. (1992)
    Springer
    Plant cell, tissue and organ culture 31 (1992), S. 211-214 
    Details
    ISSN: 1573-5044
    Keywords: carbohydrate ; germination ; Impatiens L. ; Impatiens platypetala L. ; nitrogen ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro germination of 20-day old immature ovules of Impatiens platypetala Lindl. was inhibited at concentrations as low as 50 mM sucrose or mannitol and 100 mM glucose. Younger ovules (12, 14, and 16 days old) were similarly inhibited at 100 mM sucrose. Inorganic nitrogen concentration did not affect germination regardless of ovule age, but seedling fresh weight was significantly less and abnormal development of seedlings was significantly increased by total inorganic nitrogen concentrations higher or lower than 30 mM (at a ratio of 20: 10 mM NO3 -: NH4 +) in the culture medium.
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    Nitrate and ammonium as nitrogen sources for lupins prior to nodulation (1992)
    Springer
    Plant and soil 139 (1992), S. 247-251 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; lupins ; nitrate ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two cultivars of Lupinus angustifolius L. were grown in a glasshouse in solutions containing NO3 -, NH4 + or NH4NO3 with a total nitrogen concentration of 2.8 M m-3 in each treatment. One cultivar chosen (75A-258) was relatively tolerant to alkaline soils whereas the other (Yandee) was intolerant to alkalinity. Controlled experiments were used to assess the impact of cationic vs. anionic forms of nitrogen on the relative performance of these cultivars. Relative growth rates (dry weight basis) were not significantly different between the two cultivars when grown in the presence of NO3 -, NH4 + or NH4NO3. However, when NO3 - was supplied, there was a modest decline in relative growth rates in both cultivars over time. When plants grown on the three sources of nitrogen for 9 days were subsequently supplied with 15NH4NO3 or NH4 15NO3 for 30 h, NH4 + uptake was generally twice as fast as NO3 - uptake, even for plants grown in the presence of NO3 -. Low rates of NO3 - uptake accounted for the decrease in growth rates over time when plants were grown in the presence of NO3 -. It is concluded that the more rapid growth of 75A-258 than Yandee in alkaline conditions was not due to preferential uptake of NH4 + and acidification of the external medium. In support of this view, acidification of the root medium was not significantly different between cultivars when NH4 + was the sole nitrogen source.
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    Influence of plant nutrient concentration on growth rate: Use of a nutrient interruption technique to determine critical concentrations of N, P and K in young plants (1992)
    Springer
    Plant and soil 142 (1992), S. 221-233 
    Details
    ISSN: 1573-5036
    Keywords: critical concentration ; deficiency ; diagnosis ; growth rate ; lettuce ; luxury consumption ; nitrogen ; nitrate ; nutrient requirement ; petiole sap ; phosphorus ; phosphate ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A method is described for determining the way in which growth rate varies with plant nutrient concentration using a simple nutrient interruption technique incorporating only 2 treatments. The method involves measuring the changes in growth and nutrient composition of otherwise well-nourished plants after the supply of one particular nutrient has been withheld. Critical concentrations are estimated from the relationship between the growth rate (expressed as a fraction of that for control plants of the same size which remained well-nourished throughout) and the concentration of the growth-limiting nutrient in the plants as deficiency developed. Trials of the method using young lettuce plants showed that shoot growth rate was directly proportional to total N (nitrate plus organic N) concentration, and linearly or near-linearly related to K and P concentration over a wide range; the corresponding relationship for nitrate was strongly curvi-linear. Critical concentrations (corresponding to a 10% reduction in growth rate) determined from these results were similar to critical values calculated from models derived from field data, but were generally higher than published estimates of critical concentration (based on reductions in shoot weight) for plants of a similar size. Reasons for these discrepancies are discussed. Nitrate, phosphate or potassium concentrations in sap from individual leaf petioles were highly sensitive to changes in shoot growth rate as deficiency developed, with the slope of the relationships varying with leaf position, due to differences both in their initial concentration and in the rates at which they were utilized in individual leaves. Each nutrient was always depleted more quickly in younger leaves than in older ones, providing earlier evidence of deficiency for diagnostic purposes. Although the plants were capable of accumulating nitrate, phosphate and potassium well in excess of that needed for optimum dry matter production during periods of adequate supply, the rate of mobilization of these reserves was insufficient to prevent reductions in growth rate as the plants became deficient. This brings into question the validity of the conventional concept that luxury consumption provides a store of nutrients which are freely available for use in times of shortage. The implications of these results for the use of plant analysis for assessing plant nutrient status are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010968
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  • 95
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    The effect of nitrogen fertilizer and irrigation on black point incidence in soft white spring wheat (1992)
    Springer
    Plant and soil 140 (1992), S. 41-47 
    Details
    ISSN: 1573-5036
    Keywords: Alternaria alternata ; black point ; fertilization ; irrigation ; nitrogen ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agronomic studies were conducted to examine the effect of fertilizer N on black point incidence in Fielder soft white spring wheat (Triticum aestivum L. em Thell.). Black point incidence rose with increases in the amount of N supplied either as fertilizer applied during the growing season in irrigation water or as soil N, specifically nitrate, from fertilizer N application in previous years. A comparison of four different irrigation regimes demonstrated that black point incidence was highest under frequent irrigation (irrigate to field capacity at 75% available moisture) and lowest under conventional irrigation (irrigate to field capacity at 50% available soil moisture). In each irrigation regime, disease incidence increased as N rates were raised from 0 to 120 kg ha-1. A residual fertilizer-N study demonstrated in 1985 and 1986 that black point incidence generally rose with increasing levels of nitrogen from either preplant applications in the spring or soil nitrate from the previous year. However, additions of fertilizer N were shown to slightly reduce black point incidence at soil nitrate levels above 150 kg ha-1. A two-year fertilizer N study demonstrated that in treatments receiving the same amount (90 kg ha-1) of fertilizer N, the amount broadcast as a preplant treatment versus the amount applied in irrigation water in a fertigation treatment had no effect on black point incidence, but all fertilized treatments had significantly higher levels of disease than the unfertilized check.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012805
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  • 96
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    Barley response to nitrogen and non-nutritional benefits of legume green manure (1992)
    Springer
    Plant and soil 142 (1992), S. 19-30 
    Details
    ISSN: 1573-5036
    Keywords: barley ; fertilizer ; green manure ; legume ; lentil ; nitrogen ; non-nutritional response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Green manure application may benefit subsequent crops not only by improving nitrogen (N) fertility but also via non-nutritional mechanisms. The quantification of the latter effect, however, is complicated by the confounding effect of N fertility. Two experiments were conducted in controlled environments to partition the yield response of barley to green manure between N and non-nutritional effects. Each experiment included a factorial of fertilizer N application rates and green manure application rates. The fertilizer was labelled with 15N to facilitate discrimination between N sources. Approximately 24% of the N applied in green manure was assimilated by barley after 45 days (Experiment 1) and 32% was recovered by barley grown to maturity (Experiment 2). Apparent recovery of green manure-N by barley was not appreciably affected by fertilizer application. Regression analysis of the relationship between dry matter yield and plant N uptake demonstrated that yield responses to green manure application were not entirely attributable to improved N fertility. For a given amount of N assimilated by the crop, yields were higher in green manure-amended treatments than in those receiving no green manure. In barley grown to maturity, barley response to N and non-nutritional effects were estimated to be 5.3 and 2.2g pot−1, respectively. The relationship between dry matter yield and N uptake is suggested as a method for distinguishing nutritional and non-nutritional yield responses. This approach assumes that no other nutrient is limiting growth. The presence of non-nutritional benefits observed in this study demonstrates that the agronomic value of green manure is not limited to N release and casts doubt on the assumptions inherent to calculation of fertilizer equivalents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010171
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  • 97
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    Nitrogen mineralization and its controlling factors in various kinds of temperate humid-zone soils (1992)
    Springer
    Plant and soil 144 (1992), S. 31-44 
    Details
    ISSN: 1573-5036
    Keywords: mineralization capacity ; nitrogen ; principal components analysis ; soil incubation ; temperate humid zone ; soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The N mineralization capacity of 41 temperate humid-zone soils of NW Spain was measured by aerobic incubation for 15 days at 28°C and 75% of field capacity. The main soil factors affecting organic N dynamics were identified by principal components analysis. Ammonification predominated over nitrification in almost all soils. The mean net N mineralization rate was 1.63% of the organic N content, and varied according to soil parent materials as follows: soils on basic and ultrabasic rocks 〈 soils over acid metamorphic rocks 〈 soils developed over sediments 〈 soils over acid igneous rocks 〈 soils on limestone. The N mineralization capacity was lower in natural soils than in cropped soils or pastures. The accumulation of organic matter (C and N) seems to be due to poor mineralization which was caused, in decreasing order of importance, by high exchangeable H-ion levels, high Al and Fe gel contents and, to a lesser extent (though more markedly in cropped soils), by silty clay texture and exchangeable Al ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018842
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  • 98
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    Inability to solubilize phosphate in limestone soils—key factor controlling calcifuge habit of plants (1992)
    Springer
    Plant and soil 145 (1992), S. 65-70 
    Details
    ISSN: 1573-5036
    Keywords: calcifuge plants ; phosphorus ; deficient absorption ; Deschampsia flexuosa ; Jasione montana ; Rumex acetosella ; Silene rupestris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Germination, seedling establishment and growth of calcifuge plants in Swedish limestone soils of Archean and Ordovician age were studied. As previously demonstrated for Viscaria vulgaris, establishment of Rumex acetosella and Silene rupestris did not succeed unless CaHPO4 (at the rate of 10 mmol dm-3 of soil) was supplied. Growth of Deschampsia flexuosa was enhanced by phosphate addition, whereas establishment success of Jasione montana was poor, regardless of phosphate treatment. Establishment and growth in an acidic gneiss soil, used as a reference for the species studied, was good. Total, total inorganic, exchangeable, and soil solution P were considered in all soils and treatments. It is proposed that the calcifuge behaviour of plants is quite often caused by inability to solubilize the native phosphate of limestone soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009542
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  • 99
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    Effect of aluminium on the growth of 34 plant species: A summary of results obtained in low ionic strength solution culture (1992)
    Springer
    Plant and soil 146 (1992), S. 61-66 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; asparagus ; Arabidopsis ; bean ; cereals ; grass ; legume ; Nicotiana ; petunia ; relative tolerance ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The results from many experiments conducted over 5 years to determine the tolerance of 34 plant species (87 cultivars) to aluminium (Al) are summarised. All experiments were conducted in a temperature-controlled glasshouse using a low-ionic-strength solution culture technique. The activity of Al3+ (μM) at which top yields were reduced by 50% (AlRY50) was determined for each cultivar. The species Bromus wildenowii, Cynosurus cristatus, Hordeum vulgare, Triticum aestivum (cvs Warigal, Scout, Sonora-63), Avena byzantina, Arabidopsis thaliana, Lycopersicon esculentum and Nicotiana plumbaginifolia were all very sensitive to Al (AlRY50〈1). The species Poa pratense, Lolium perenne (NZ-derived cultivars), Lotus corniculatus, Avena sativa (cvs West, Carbeen, Camellia and Coolabah), Triticum aestivum (cvs Cardinal and Waalt), Allium cepa and Asparagus officinalis were sensitive to Al (AlRY50 1–2). The pasture grass species Lolium perenne (Australian and European and derived cultivars), Lolium hybridum and Lolium multiflorum, Dactylis glomerata (Apanui and Kara), Phalaris aquatica, Festuca arundinacea and the pasture legumes species Trifolium pratense, Trifolium repens and Trifolium subterraneum were all moderately sensitive to Al (AlRY50 2–5). Other species that were also moderately sensitive included Triticum aestivum (cvs Atlas-66, BH146, and Carazinho), Avena sativa (cvs Swan and Blackbutt), Avena Strigosa, Petunia x and Phaseolus vulgaris (cvs Red Kidney, Black Turtle and Haricot). The most tolerant species (AlRY50〉5) were (in order of increasing tolerance) Phaseolus vulgaris (cvs Tendergreen, The Prince and Yatescrop), Cucurbita maxima, Dactylis glomerata (cv Wana), Paspalum dilatatum, Lotus pedunculatus, Ehrharta calycina, Medicago sativa, Holcus lanatus, Festuca rubra, Phaseolus lunatus and Agrostis tenuis. Agrostis tenuis was at least twice as tolerant as the next most tolerant species (AlRY50〉30 compared to 15.6).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011996
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  • 100
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    Can maize cultivars with low mineral nutrient concentrations in the grains help to reduce the need for fertilizers in third world countries? (1992)
    Springer
    Plant and soil 146 (1992), S. 227-231 
    Details
    ISSN: 1573-5036
    Keywords: cultivars ; grains ; maize ; nitrogen ; phosphorus ; potassium ; tropical climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An earlier study revealed considerable genotypic variation in grain N, P and K concentrations (GNC, GPC and GKC, respectively) in tropical maize. The expression of varietal differences in GNC, GPC and GKC, however, may depend on environmental conditions such as the N status of the soil. Two tropical maize hybrids (Suwan 2301 and CP 1) with comparable yielding capacity, but contrasting GNCs, GPCs and GKCs, were therefore grown at four levels of N in a field experiment at Farm Suwan (Thailand, latitude 14.5°N). Suwan 2301 exhibited a higher GNC than did CP 1 at all rates of N, but large differences in GPC and GKC were found only at high N fertilization. This was obviously due to individual grain yield responses of the cultivars to increasing rates of N fertilizer, demonstrating that grain nutrient concentrations are, at least in part, functions of the amount of grain carbohydrates which dilute a genetically and environmentally fixed amount of grain P and K. As compared to Suwan 2301, CP 1 accumulated less N, P and K in the grains at almost all levels of N fertilization, confirming our hypothesis that the cultivation of maize genotypes with low grain mineral nutrient concentrations may help third-world cash-crop farmers to reduce the need for scarce and costly mineral fertilizers. This finding has to be verified at reduced availability of soil −P, −K, and water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012016
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