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  • 1
    Electronic Resource
    Electronic Resource
    The involvement of gonadotrophin and sex steroids in the control of reproduction in the parr and adults of Atlantic salmon, Salmo salar L. (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 18 (1981), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Early sexual maturity occurred in the majority of male Atlantic salmon parr. Levels of the plasma androgens testosterone and 11-ketotestosterone rose steadily as the male parr matured, and decreased as the testes regressed. No such progressive changes were observed in the plasma gonadotrophin (GTH) levels, although the pituitary GTH levels were much higher in mature than in immature male parr; reasons for this, incluiding the possibility that the GTH radioimmunoassay employed is inadequate, are discussed. All female parr remained immature throughout the year, although the gonadosomatic index did show an annual cycle. Adult salmon had higher GTH and sex steroid levels than parr at the same stage of sexual maturity, the levels corresponding to the degree of sexual development of the adult fish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1981.tb03760.x
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  • 2
    Electronic Resource
    Electronic Resource
    The annual reproductive cycle of the female lesser spotted dogfish, Scyliorhinus canicula L., and its endocrine control (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 15 (1979), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Various aspects of the reproductive physiology of the female lesser spotted dogfish, Scyliorhinus canicula L., demonstrate marked annual cycles. Pituitary ventral lobe gonadotrophin content and plasma oestradiol and testosterone levels rise through the autumn as the ovary recrudesces and the percentage of fish bearing eggs in the oviducts increases. The pituitary gonadotrophin and plasma sex steroid levels remain elevated throughout the winter but decrease during the spring, two months prior to a fall in both the gonadosomatic index (GSI) and the percentage of fish with eggs in their oviducts. The lowest gonadotrophin and sex steroid levels are found in early summer, again preceding the minimum GSI and rate of egg-laying by two or three months. Some of these cycles are pronounced, the pituitary gonadotrophin levels varying by more than 100-fold, and the oestradiol levels by more than 10-fold, throughout the year. It is concluded that the female dogfish has a very extended breeding season, though the peak frequency of egg-laying occurs in the winter and spring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1979.tb03678.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of ovariectomy of the dogfish Scyliorhinus canicula L. on circulating levels of androgen and oestradiol and on pituitary gonadotrophin content (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 21 (1982), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Levels of androgens and oestradiol in dogfish, Scyliorhinus canicula, plasma, measured by radioimmunoassay, decrease markedly after ovariectomy (OVX). The magnitude and latency of these responses varies according to length of captivity preceding the operation and the time of year at which ovariectomy is performed. Androgens are cleared more rapidly than oestradiol from plasma following OVX, and levels of both steroids are reduced after laparotomy (LAP) in November but not in March. An extract of ventral lobes of the dogfish pituitary induces a significant increase in the circulating androgen levels in LAP fish but not in OVX fish, indicating that the ovary is the major site of androgen production in response to stimulation by dogfish gonadotrophin. Intramuscular injections of oestradiol benzoate (2.5 mg per fish) into LAP fish produce a significant reduction in the gonadotrophin content of the pituitary ventral lobe, measured in the quail testicular cell bioassay, when compared to LAP and unoperated controls. However, no significant changes in the gonadotrophin content of the ventral lobe were seen five days after OVX in June.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1982.tb02834.x
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  • 4
    Electronic Resource
    Electronic Resource
    Ciliary Feeding Mechanisms in Anuran Larvæ (1950)
    [s.l.] : Nature Publishing Group
    Nature 165 (1950), S. 283-283 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Recent work here has shown the earlier account of Bles to be correct. In particular, it has not been found possible to demonstrate the presence of cilia on the pharyngo-branchial tract, though rhythmical movements of this area during gulping may serve to direct incoming food particles into the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/165283a0
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  • 5
    Electronic Resource
    Electronic Resource
    Assay of Thyroid-stimulating Hormone, Thyroid and Thyroid-like Substances on Xenopus Tadpoles (1953)
    [s.l.] : Nature Publishing Group
    Nature 172 (1953), S. 121-122 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Onset and progress of metamorphosis depend upon the amount of active iodine ingested by the larva in its food. Different foods vary widely in their content of active iodine; for example, eight batches of commercial liver powder produce emergence of front limb in similar batches of larvae in times ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/172121a0
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  • 6
    Electronic Resource
    Electronic Resource
    Thyroid Gland and Temperature Tolerance Relationships in Cold-blooded Vertebrates (1963)
    [s.l.] : Nature Publishing Group
    Nature 199 (1963), S. 299-299 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] As a preliminary to further work on these aspects of thyroid physiology, and in an attempt to confirm and extend the work of Fortune, one of us (J. M. D.) set out to repeat the work on minnows already described. Fish were obtained from Lake Windermere in September and October and a series of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/199299a0
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  • 7
    Electronic Resource
    Electronic Resource
    A Neurohypophyseal Principle in the Elasmobranch Pituitary (1960)
    [s.l.] : Nature Publishing Group
    Nature 185 (1960), S. 850-851 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Pituitary glands were removed from freshly killed Squalus acanthias, Scyliorhinus caniculus, Raia clavata, R. batis and R. naevus, separated into their constituent lobes, and dried in acetone. The resulting powders were extracted with 0-25 per cent acetic acid by the standard method for ox ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/185850a0
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  • 8
    Electronic Resource
    Electronic Resource
    Force-Feeding Fish under Experimental Conditions (1959)
    [s.l.] : Nature Publishing Group
    Nature 184 (1959), S. 1660-1661 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It is not known whether hypophysectomized fish would accept squid muscle, or whether such a diet would give an acceptable survival time, since squid is not usually available in this Laboratory. But even if it was found to be satisfactory from these points of view, the difficulty still remains that ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/1841660a0
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  • 9
    Electronic Resource
    Electronic Resource
    Maturity and Fecundity of One-Year-Old English Native Oysters, O. edulis (1937)
    [s.l.] : Nature Publishing Group
    Nature 139 (1937), S. 108-109 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] BY the courtesy of Major A. Gardner, one of us (J. H. O.) was able to study the spawning, spatfall and growth of the native oyster, O. edulis, on the Blackwater and Roach oyster beds in 1935 and 1936. The summer of 1935 resembled that of 1921 in being continuously warm, and also in yielding ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/139108a0
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  • 10
    Electronic Resource
    Electronic Resource
    Rate of Growth of Totally Submerged Cardium edule (1937)
    [s.l.] : Nature Publishing Group
    Nature 139 (1937), S. 799-800 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] BY good fortune, data on the growth of Cardium edule have now been collected covering four summers' growth. This bivalve is usually found between tide-marks, but it occurs also below low-water mark in this and other localities. The material for the present study was taken from the bottom ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/139799a0
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