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  • Immunocytochemistry  (32)
  • Calcium
  • Springer  (50)
  • PANGAEA
  • 1990-1994  (50)
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  • 1
    Electronic Resource
    Electronic Resource
    Calcium plays a central role in phase shifting the ocular circadian pacemaker of Aplysia (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 415-423 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00199249
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  • 2
    Electronic Resource
    Electronic Resource
    Amelioration of subsoil acidity in an Oxisol of the humid tropics (1993)
    Springer
    Biology and fertility of soils 15 (1993), S. 153-159 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336435
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  • 3
    Electronic Resource
    Electronic Resource
    Functional morphology of the light yellow cell and yellow cell (sodium influx-stimulating peptide) neuroendocrine systems of the pond snail Lymnaea stagnalis (1994)
    Springer
    Cell & tissue research 275 (1994), S. 361-368 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319435
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  • 4
    Electronic Resource
    Electronic Resource
    Immunoreactivity to the pancreatic polypeptide family in the nervous system of the adult human blood fluke, Schistosoma mansoni (1990)
    Springer
    Cell & tissue research 261 (1990), S. 573-581 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313537
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  • 5
    Electronic Resource
    Electronic Resource
    Islet amyloid polypeptide (amylin) increases the renal excretion of calcium in the conscious dog (1994)
    Springer
    Calcified tissue international 55 (1994), S. 269-273 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310405
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  • 6
    Electronic Resource
    Electronic Resource
    Combined magnetic fields increased net calcium flux in bone cells (1994)
    Springer
    Calcified tissue international 55 (1994), S. 376-380 
    Details
    ISSN: 1432-0827
    Keywords: Electromagnetic ; Bone ; Calcium ; Osteoblast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Low energy electromagnetic fields (EMF) exhibit a large number of biological effects. A major issue to be determined is “What is the lowest threshold of detection in which cells can respond to an EMF?” In these studies we demonstrate that a low-amplitude combined magnetic field (CMF) which induces a maximum potential gradient of 10-5 V/m is capable of increasing net calcium flux in human osteoblast-like cells. The increase in net calcium flux was frequency dependent, with a peak in the 15.3–16.3 Hz range with an apparent bandwidth of approximately 1 Hz. A model that characterizes the thermal noise limit indicates that nonspherical cell shape, resonant type dynamics, and signal averaging may all play a role in the transduction of lowamplitude EMF effects in biological systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299318
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of liposome-encapsulated and free clodronate on the growth of macrophage-like cellsin vitro: The role of calcium and iron (1993)
    Springer
    Calcified tissue international 53 (1993), S. 139-146 
    Details
    ISSN: 1432-0827
    Keywords: Clodronate ; Liposomes ; Macrophages ; Calcium ; Iron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Clodronate (dichloromethylene bisphosphonate) inhibits the activity of osteoclasts, thereby preventing bone resorption in disorders characterized by excessive bone loss. Intravenously injected clodronate encapsulated in liposomes is also known to inactivate phagocytic cells in spleen and liverin vivo. The macrophage suppressive effect of clodronate is of interest in autoimmune diseases, like rheumatoid arthritis, in which phagocytic cells are involved in inflammatory processes, but knowledge of the interaction of clodronate with phagocytic cells is scarce. We have studied the uptake of clodronate, both free and encapsulated in negatively charged liposomes, by the macrophage-like cell line RAW 264 and by other types of cell lines. The uptake was assessed by a growth inhibition assay. The liposome-encapsulated lodronate was 50 and 350 times more potent than free drug for RAW 264 and CVI-P, respectively. Cell lines with a lower endocytotic capacity were insensitive to liposome-mediated delivery of the drug. The action of free clodronate seemed to be extracellular in all cell lines studied. Calcium and/or iron have been suggested to be involved in the intracellular uptake and action of clodronate in phagocytic cells. We found that the uptake of free clodronate by RAW 264 cells was indeed mediated by calcium and iron, while the uptake of liposomal drugs was only slightly affected by calcium. The increased intracellular calcium concentration in macrophages did not significantly affect the growth-inhibitory properties of clodronate, whereas iron loading of the cells partially restored the cell growth. The data do not support the role of calcium chelation as a mechanism of action of clodronate, but suggest that intracellular iron is, at least partially involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01321893
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  • 8
    Electronic Resource
    Electronic Resource
    The effect of variation in calcium intake on the growth of wood mice and bank voles (1992)
    Springer
    Oecologia 92 (1992), S. 130-137 
    Details
    ISSN: 1432-1939
    Keywords: Wood mouse ; Bank vole ; Calcium ; Growth ; Body weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Calcium intake by wild rodents varies with season and habitat. This may have important ecological consequences; several studies have suggested that calcium availability may limit growth and reproduction. We studied the effect on growth of varying the calcium intake of captive wood mice Apodemus sylvaticus (L.) and bank voles Clethrionomys glareolus (Schreber 1780). To determine whether effects observed in the laboratory could be detected in free-living animals, we also compared the body weights and lengths of free-living animals on calcium-poor gritstone areas with those of rodents on calcium-rich limestone habitats where the dietary calcium concentration was between 2 and 5 times higher. Captive wood mice fed high calcium (0.87%) diet grew at the same rate as mice fed low calcium (0.30%) diet but continued growing for longer, thereby achieving higher asymptotic weights. In contrast, captive bank voles fed the high calcium diet grew more slowly and had lower asymptotic weights than voles fed the low calcium diet. As expected from the laboratory growth study, the higher calcium intake of free-living wood mice on the limestone was associated with greater body size compared with mice on the gritstone. However, bank voles were also larger on the limestone, even though high calcium intake impaired growth in captive animals. The contrast between wood mice and bank voles in the effects of calcium on growth, the reason why impaired growth may not be apparent in bank voles from calcium-rich habitats and the ecological significance of these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317273
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of habitat geology on calcium intake and calcium status of wild rodents (1991)
    Springer
    Oecologia 88 (1991), S. 539-546 
    Details
    ISSN: 1432-1939
    Keywords: Wood mouse ; Bank vole ; Calcium ; Femur ; Ash
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Calcium is essential for normal physiological function, reproduction and growth in mammals but its distribution in the natural environment is heterogeneous. Spatial variation in calcium soil content is especially marked in the Peak District, United Kingdom, where both calcium-rich limestone and calcium-poor gritstone rock types occur. Wood mice Apodemus sylvaticus (L) and bank voles Clethrionomys glareolus (Schreber 1780) from limestone areas had significantly higher calcium concentrations in stomach contents and in faeces compared with their counterparts from gritstone areas. Calcium status was assessed from serum calcium concentration, femur weight, ash content of the body, calcium concentration in the femur and body ash. There was no significant difference in serum calcium concentration, femur calcium concentration and body ash calcium concentration between animals from the limestone and the gritstone. However, on the limestone, bank voles, but not wood mice, had significantly heavier femora and a greater proportion of ash in the body compared with their gritstone counterparts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317717
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  • 10
    Electronic Resource
    Electronic Resource
    Synergid degeneration in Nicotiana: a quantitative, fluorochromatic and chlorotetracycline study (1992)
    Springer
    Sexual plant reproduction 5 (1992), S. 151-155 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194875
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