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  • Immunocytochemistry  (32)
  • phosphorus  (28)
  • Calcium
  • Springer  (78)
  • PANGAEA
  • 1990-1994  (78)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 175 (1994), S. 415-423 
    ISSN: 1432-1351
    Keywords: Aplysia ; Calcium ; Circadian ; Light ; Serotonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The eye of the marine mollusk Aplysia californica contains an oscillator that drives a circadian rhythm of spontaneous compound action potentials in the optic nerve. Both light and serotonin are known to influence the phase of this ocular rhythm. The aim of the present study was to evaluate the role of extracellular calcium in both light and serotonin-mediated phase shifts. Low calcium treatments were found to cause phase shifts which resembled those produced by the transmitter serotonin. However, unlike serotonin, low calcium neither increased ocular cAMP levels nor could these phase shifts be prevented by increasing extracellular potassium concentration. Low calcium-induced phase shifts were prevented by the simultaneous application of the translational inhibitor anisomycin and low calcium treatment resulted in changes in [35S]methionine incorporation into several proteins as measured by a two-dimensional electrophoresis gel analysis. Finally, light treatments failed to produce phase shifts in the presence of low calcium or the calcium channel antagonist nickel chloride. These results are consistent with a model in which serotonin phase shifts the ocular pacemaker by decreasing a transmembrane calcium flux through membrane hyperpolarization while light-induced phase shifts are mediated by an increase in calcium flux.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 15 (1993), S. 153-159 
    ISSN: 1432-0789
    Keywords: Calcium ; Maize ; Nitrogen ; Brazilian Amazon ; Cation leaching ; Canavalia ensiformes ; Mucuna aterrima
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This work investigated the effectsof amendments of fertilizer N and lime on subsoil acidity and maize rooting depth in an acid soil of the central Amazon basin. A split-plot designed field experiment was conducted on a clayey Oxisol (Typic Acrudox) during a 16-month period. Main plots received 0 or 4 Mt ha-1 of lime. Subplots were four crop sequences: (1) Maize-green manure (Canavalia ensiformes); (2) maize-green manure (Mucuna aterrima); (3) maize-bare fallow, with the maize receiving 300 kg ha-1 of urea-N; and (4) bare fallow, with an application of 300 kg ha-1 of urea-N at the same time as sequence 3. Plots were periodically sampled to 1.2 m. The experimental site received 4265 mm of precipitation during 16 months; approximately 60%–90% of this rain percolated through the profile. Substantial amounts of Ca were leached from the 0–30 cm horizon during the experimental period, but only limited amounts accumulated in the subsoil. Base saturation below 45 cm was less than 50% at the end of the experiment regardless of lime treatment. Roots of maize were concentrated in the 0–30 cm layers in limed plots and the 0–20 cm layers in unlimed plots. In all treatments less than 5% of the roots was found below 50 cm. An acidity balance indicated that considerable acidity was leached below the plow layer and out of the profile.
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  • 3
    ISSN: 1432-0878
    Keywords: Sodium influx-stimulating peptide, mollusc ; Neuroendocrine cells, mollusc ; Light yellow cells ; Yellow cells ; In situ hybridization ; Immunocytochemistry ; Osmoregulation ; Lymnaea stagnalis (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neuroendocrine light yellow cells of the pond snail Lymnaea stagnalis express a neuropeptide gene encoding three different peptides. The morphology of the cell system has been studied by in situ hybridization, using two synthetic oligonucleotides encoding parts of light yellow cell peptides I and III, and by immunocytochemistry with antisera to synthetic light yellow cell peptide II and to two fragments of light yellow cell peptide I. One large cluster of light yellow cells was observed in the ventro-lateral protrusion of the right parietal ganglion, smaller clusters lying in the posterior dorsal part of this ganglion and in the visceral ganglion. The cells had an extended central neurohaemal area. Immunopositive axons projected into all nerves of the ganglia of the visceral complex, into the superior cervical and the nuchal nerves, and into the connective tissue surrounding the central nervous system. Axon tracts ramified between the muscle cells of the walls of the anterior aorta and of smaller blood vessels. Peripheral innervation by the light yellow cell system was only found in muscular tissue of the ureter papilla. The antisera to the two peptide fragments of light yellow cell peptide I not only stained the light yellow cells, but also the identified yellow cells, which have previously been shown to produce the sodium influx-stimulating neuropeptide. The latter cells were negative to the in situ hybridization probes and antisera specific to the light yellow cell system. It is therefore unlikely that the yellow cells express the light yellow cell neuropeptide gene. Nevertheless, the cells contain a neuropeptide sharing antigenic determinants with light yellow cell peptide I. Our observations support the hypothesis that light yellow cells are involved in maintaining the shape of the animal via the regulation of ion- and waterbalance processes and blood pressure.
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  • 4
    ISSN: 1432-0878
    Keywords: Neuropeptides (pancreatic polypeptide, peptide YY, neuropeptide Y) ; Immunocytochemistry ; Confocal scanning laser microscopy ; Schistosoma mansoni (Scolecida, Trematoda)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The presence and distribution of neuropeptides belonging to the pancreatic polypeptide family have been demonstrated by an indirect immunofluorescence technique in the nervous systems of adult male and female Schistosoma mansoni. Seven antisera of differing regional specificity to pancreatic polypeptide (PP), peptide YY (PYY) and neuropeptide Y (NPY) were employed on both whole-mount and cryostat-sectioned material. Positive immunoreactivity (IR) was obtained with all antisera except an N-terminally-directed antiserum to NPY. In the CNS, immunoreactivity was restricted to cell bodies and nerve fibres in the anterior ganglia, central commissure and dorsal and ventral nerve cords of both sexes, whereas, in the PNS, positive-IR was present in the plexuses innervating the subtegumental musculature and the oral and ventral suckers. Intense immunoreactivity was observed in a plexus of nerve fibres and cell bodies in the lining of the gynaecophoric canal and in fine nerve fibres innervating the dorsal tubercles of the male. In contrast, in the female, strong immunoreactivity was evident in nerve plexuses innervating the lining of the ovovitelline duct and in the wall of the ootype, but most notably in a cluster of cells in the region of Mehlis' gland. Results suggest that molecules with C-terminal homology to the PP-family are present in S. mansoni. These peptides would appear to be important regulatory molecules in the parasite's nervous system and may play a role in the control of egg production.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 145 (1992), S. 45-50 
    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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  • 6
    ISSN: 1573-5117
    Keywords: urbanisation ; heavy metals ; phosphorus ; macrofossils ; lake and fluvial sediments ; lake rehabilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chemical and palaeoecological analysis of lake and fluvial sediments reveals a range of human impact on the sediment chemistry of four reservoirs in the English Midlands. Atmospheric pollution is recorded in both inner city and rural sites over the last 150 years. Catchment derived heavy metals at one urban site reveals high contamination factors for Pb, Cu, Ni, Zn and Cd. From the phosphorus record and from reconstructions based on macrofossil remains, eutrophication is recorded at all sites. Recent attempts to evaluate rehabilitation programmes for the inner city sites have proved problematical owing to two major problems. First, their shallow nature results in a high cost of desilting and, secondly, heavy metal contamination makes treatment and disposal of the sediment expensive.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 115-122 
    ISSN: 1573-0867
    Keywords: phosphorus ; retention ; release ; sandy soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to manage phosphorus (P) losses from soils to waterbodies, knowledge of the mechanisms through which P is retained or released from the soil is essential. Sandy soils of the Peel-Harvey catchment (Western Australia) were subjected to a range of environmental and management factors in the laboratory and field in order to gain an understanding of the mechanisms that affect the magnitude of P losses. Sandy soils accumulated P, despite having little sorption capacity, and this accumulation could be monitored by measuring an acid-extractable fraction. The potential, short-term P loss could be estimated by determination of water-soluble soil solution P prior to winter rains. An annual cycle of the change in arbitrarily defined soil-P pools is discussed in relation to environmental and management factors. Laboratory experiments indicated that P rundown and potential annual P loss in the absence of P fertilizers could be estimated using bicarbonate extractable P. Phosphorus losses were decreased by the application of fertilizers with a low content of water-soluble P. The low ability of sandy soils of the Peel-Harvey coastal catchment to retain P, when compared to other Western Australian soils, is because of low contents of clay minerals and iron and aluminium hydrous oxides.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 223-227 
    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.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 54 (1992), S. 381-390 
    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.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 55 (1994), S. 269-273 
    ISSN: 1432-0827
    Keywords: Islet amyloid polypeptide ; Amylin ; Calcium ; Urine ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Islet amyloid polypeptide (IAPP) is a member of the calcitonin/CGRP family and has been isolated from the β-cell of pancreatic islets. Recent evidence suggests that this peptide may be involved in calcium metabolism in that its administration resulted in lowering of serum calcium levels. To determine the mechanism of IAPP-induced hypocalcemia, the peptide was infused at 50 pmol/min/kg for 90 minutes in conscious male mongrel dogs. Infusion of the peptide resulted in a modest decline in the total serum calcium concentration (10.4±0.2 to 9.4±0.2 mg/dl; P〈0.05) and a concomitant increase in urinary calcium excretion (3.6±0.6 to 6.9±2.0 mg/dl; P〈0.01). Based on an extracellular volume of 7 liter in a 28 kg dog, the total decrement in calcium due to IAPP was 41.3±2.4 mg, whereas the total increase in urinary calcium was 3.2±0.7 mg. There were no detectable changes in calcitonin. We conclude that IAPP lowers serum calcium and increases the renal excretion of calcium independently of calcitonin. However, the calciuria can only account for a small component of the hypocalcemic effect and therefore, an additional calcium lowering effect of IAPP exits.
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