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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 13 (1982), S. 1-21 
    ISSN: 0066-4162
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Water and sediment samples from ten unpolluted sandy beaches have been analysed for various chemical parameters and meiofauna. The results have indicated that, within the range of grain sizes found, (196–337 μm), short term fluctuations in the natural levels of the various chemical constituents do not significantly influence the densities of meiofauna populations. These are, however, governed largely by the median grain size of the sediments. The relationships between median grain size and the population densities of nematodes and harpacticoid copepods have been established. The optimum grain size for the populations studied was 284 μm, and as the sediment size deviated from this, the population density decreased. Thus knowledge of the median grain size of sediments should indicate the approximate meiofaunal density which can be expected in the absence of any other external influence. Deviations from this can then be attributed to perturbation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Since 1975, pollution surveys have been carried out along the South African south and west coasts as part of a monitoring program of unpolluted areas and known and anticipated impact areas. To evaluate these data a reference or baseline level was needed. In unpolluted beaches a close relationship between meiofauna and sediment grain size was found and granulometric analysis was found to be important. This relationship was used to evaluated perturbation effects. It was found that contamination by chemical effluent depressed numbers of the nematodes and harpacticoids drastically. Mechanical perturbation increased the number of harpacticoid copepods but did not affect nematode densities. Oil in beaches decreased the number of harpacticoids, while normal nematode densities were found. Organic enrichment increased the number of nematodes, harpacticoid numbers remained normal while the perturbation effect due to sewage increased the number of both taxa. Explanations for these effects are given, together with related chemical analyses. The application of these results to other sandy beaches elsewhere is discussed briefly.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 1-8 
    ISSN: 1040-452X
    Keywords: Activin ; Expression ; Fecundity gene ; FecB ; Primer extension ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The 5′ untranslated region (UTR) of βA inhibin mRNA was compared in a variety of sheep tissues, using primer extension. Considerable variation in the length and number of 5′ extended products were noted between tissues. Specific bands were noted in ovarian follicular RNA, which were also present in samples from corpora lutea, stroma, and placental cotyledon RNA. Other extended products were observed in RNA from corpora lutea, stroma, cotyledon, pituitary, bone marrow, frontal cortex, medial basal hypothalamus, adrenal, liver, and kidney, which were not present or weakly represented in follicular RNA, Additional tissue-specific bands were noted in testis and bone marrow RNA. No specific differences in the lengths of the 5′ UTR of the βA inhibin mRNA were observed in sheep homozygous for the Booroola fecundity gene FecB, in any tissue studied. The coding region of ovine βA inhibin cDNA was sequenced and a genetic polymorphism confirmed within or close to the ovine βA inhibin gene.We conclude that the βA inhibin gene is expressed widely in the sheep. Furthermore there is variation in the length of the 5′ UTR of βA inhibin mRNA between male and female gonads and other tissues, implying that expression of this gene is differentially controlled. However, the FecB mutation does not affect mRNA splicing events or the initiation site used in ovarian transcription. The mechanism by which the FecB mutation influences the amounts of βA inhibin mRNA, follicle-stimulating hormone (FSH) secretion and ovulation rate has still to be elucidated. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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