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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 9 (1976), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hypophysectomy resulted in a loss of ability of the euryhaline salmonid, Salmo trutta to survive in fresh water. The mean survival time was 4–5 days. Maintenance in a medium containing 5 mM calcium increased the mean survival time to 8 days while 10 mM decreased it. Injection of 0–21.U./gm prolactin enabled hypophysectomized fish to survive the 2-week duration of the experiment.High environmental calcium, or pre-adaptation to a medium of high calcium, increased salinity tolerance of the brown trout probably by promoting a quick return of plasma electrolyte concentration to normal after transfer to sea water.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 25 (1984), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of short-term, experimentally-induced stress on the branchial water permeability of Oreochromis niloticus was studied. Both handling and thermal stress increased water permeability but apparently by different mechanisms. The enhancement of water permeability by acclimation temperatures and acute temperature changes had Q10 of 3.52 and 2.24 respectively. Environmental sodium concentration and acute hypoxia had no effect while hypercapnia and mild anaesthesia decreased water permeability. Both hypercapnia and mild anaesthesia probably elevated arterial pCO2 with a concomitant reduction of metabolism.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Higher education 14 (1985), S. 17-40 
    ISSN: 1573-174X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract The decline in Nigerian universities has been perceived conservatively by university administrators as a transient “phase of negative growth” entirely attributable to external rather than internal factors. Since a condition of decline has not been apprehended, per se, it has not been possible to take appropriate management policy actions to contain it. The pattern of management of Nigerian universities has remained largely unchanged for more than three decades despite major changes in the environment. While inadequate funding is perceived as the major factor in the present decline, this study highlights those aspects of management which may also have contributed to it - thus suggesting the need for major structural changes in management. Evidence is presented to show that expenditure per student is very low in comparison with British universities and that this will be even more so if corrections are made for the social welfare burdens of Nigerian universities which do not normally form a component of university function. Although the present study is preliminary in nature, a follow-up will focus on strategic management proposals to arrest the present decline.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 119 (1977), S. 127-139 
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Simultaneous measurements have been made of the efflux rates of tritiated water and radiosodium from the lung-fishProtopterus annectens under conditions in which the fish can either use its gills, its lungs or both for respiration. Tritiated water efflux rate was similar (43–44% h−1) when the fish was in oxygenated water with or without access to air but decreased slightly in deoxygenated water. An efflux rate constant of 44% h−1 obtained in oxygenated water is similar to those of other inactive fish in fresh water. The efflux rate constant for sodium was 0.84% h−1 and total sodium flux was comparable to that of fresh-water fish. The decrease in both tritiated water and sodium efflux rates in deoxygenated water are explained in terms of diversion of blood flow away from the functional gills to the lungs. Oxygen consumption was highest (38.7 ml kg−1 h−1) in deoxygenated water and lowest when the fish was out of water. Despite the reduced functional significance of the gill for respiration, it is still as permeable to water and electrolytes as that of fresh-water teleosts.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 149 (1982), S. 107-113 
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The isolated head preparation of the toadfish,Opsanus beta, perfused at constant flow rate was used to investigate the branchial vasoactive responses of the fish to adrenergic and cholinergic agonists. The perfused head maintained a relatively consistent and near in vivo branchial vascular resistance for periods of at least 8 h. Adrenergic stimulation of the isolated head produced a vasodilatory response acting via alpha and beta adrenergic receptor sites. However, the alpha adrenoceptor-mediated (vasoconstrictory) response was not observed before the dominant beta adrenoceptor-mediated (vasodilatory) response. Carbachol caused an increase in perfusion pressure which was inhibited by atrophine; thus indicating that the carbachol effect was via muscarinic receptors. The vasoconstrictory response to carbachol, unlike that of acetylcholine persisted even after withdrawal of the drug apparently due to its strong binding to receptor sites and relatively low susceptibility to attack by acetylcholinesterase. Carbachol and adrenaline influenced each other's individual vasoactive effects thus indicating a possible interaction between sympathetic and parasympathetic neurotransmitters in the regulation of branchial vasomotor tone and, consequently, branchial vascular haemodynamics.
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