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  • 1
    Electronic Resource
    Electronic Resource
    Content, absorption quantities and intracellular storage sites of heavy metals in Diplopoda (Arthropoda) (1995)
    Springer
    BioMetals 8 (1995), S. 37-46 
    Details
    ISSN: 1572-8773
    Keywords: Diplopoda ; EELS ; ESI ; heavy metals ; midgut ; spherites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract By means of atomic absorption spectrophotometry, concentrations of more than 2500 mg kg−1 Pb, 150 mg kg−1 Zn, and 320 mg kg−1 Cd could be detected in the intestine tissues of diplopods from a lead and silver smelter's spoil bank. While only small portions of the ingested lead and cadmium are absorbed in the midgut of these diplopods, the zinc uptake into the midgut epithelium reaches 33.8–37.5% of the zinc content in the food pulp when the animals were contaminated acutely. However, after long-term contamination with zinc, absorption and excretion of this metal balanced one another. Absorbed lead and cadmium are predominantly stored in the midgut cells of the diplopods; unspecific precipitation of heavy metal showed the spherites of the resorptive epithelial cells to be the main accumulation sites. Zinc is for the most part localized in or near the cuticle; electron energy loss spectroscopy and ESI electron spectroscopic imaging, however, showed this metal to be present also in the spherites of the midgut's resorption cells. These spherites are assigned to belong to the ‘type A granule’ group since (i) they are concentrically structured, (ii) they are shown to contain great amounts of calcium and (iii) copper, a class B metal, could not be detected in these deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156156
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  • 2
    Electronic Resource
    Electronic Resource
    Calcium localization in the shell-forming tissue of the freshwater snail,Biomphalaria glabrata: a comparative study of various methods for localizing calcium (1992)
    Springer
    Journal of molecular histology 24 (1992), S. 927-938 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The routes calcium might take across the mantle to the shell have been investigated with various electron-microscopical techniques in the freshwater snailBiomphalaria glabrata (Planorbidae, Basommatophora). In chemically-fixed tissue, calcium was precipitated with a tannic acid-antimonate technique in predominantly the intercellular spaces of the outer mantle epithelium and the interstitium below it. Some vacuoles of the outer mantle epithelium and one type of mucus cell in the inner mantle epithelium also contained precipitate. The presence of calcium in the precipitates was proved by electron energy loss spectroscopy combined with electron spectroscopic imaging. Incubation with lead acetate and uranyl acetate revealed binding-sites for calcium in the intercellular spaces of the epithelia interstitium and the mucus cells of the inner mantle epithelium. Precipitates were also seen after all incubations in the calcium spherites of the connective tissue. The concentrations of calcium and other elements were analysed in freeze-dried ultrathin sections of cryofixed mantle tissue by means of energy-dispersive X-ray microanalysis. Only in mitochondria of the musculature could high amounts of calcium and phosphorous be detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046498
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  • 3
    Electronic Resource
    Electronic Resource
    Comparative methodological investigations on the cytochemical localization of calcium in brain and inner ear of cichlid fish (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 31 (1995), S. 317-325 
    Details
    ISSN: 1059-910X
    Keywords: Cytochemistry ; Quantification ; EFTEM ; Teleost ; Tectum opticum ; Hair cell ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Four different methods for calcium precipitation are compared in the optic tectum and the inner ear of the cichlid fish, Oreochromis mossambicus. Several parameters are investigated concerning their influences on the reaction product. Three procedures (bichromate, fluoride, and oxalate-pyroantimonate) produce fine-grained deposits, often flocculent in the latter method. The fourth method (potassium-pyroantimonate) generates predominantly coarse-grained reaction product. The calcium content of the deposits is always proven with energy-filtering transmission electron microscopy (EFTEM). In both tissues fine-grained reaction product is found in endoplasmic reticulum and synaptic vesicles, and in addition in some mitochondria and at the cytoskeleton. The coarse-grained deposits of the potassium-pyroantimonate method have a more unspecific distribution. This is the only method which produces extracellular deposits in the inner ear, whereas in the optic tectum extracellular precipitates are always present except with the oxalate-pyroantimonate procedure. Two factors have an influence on the reaction product: the duration of fixation and the type of resin. The prolongation of the fixation time up to 24 hours leads to an increase of the reaction product, which also becomes coarse-grained. These observations are corroborated by quantification with image analysis. Furthermore the use of an epoxy resin compared to acrylic resins decreases the amount of reaction product produced. We show that the application of several methods is meaningful in order to understand the calcium properties of the investigated tissue, but it is necessary to optimize a certain method for a given tissue. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070310410
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    Paper (German National Licenses)
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