Rainbow trout exposed to environmental free CO2 concentrations ranging from 12-60 mg/1 for a minimum of 275 days developed nephrocalcinosis. Gross, histopathological and chemical examinations demonstrated that prevalence and severity of nephrocalcinosis increased with increasing CO2 concentrations. The condition was characterized by calcification and granuloma formation in kidney and stomach. Diet, but not water, PO4-P concentration appeared to modify the prevalence and severity at each CO2 concentration tested.
Summary. The These results indicate that photoperiod is the major environmental factor in the control of the sequence of endocrine and other physiological changes which ultimately lead to spawning in salmonids and suggest that photoperiod may act by modifying an inherent reproductive rhythm.Introduction.
We examined the basic pharmacology of abalone gut tissues for adrenergic and peptide receptors using ligand binding and by determining the pharmacological effectors of abalone gut motility in a number of gut regions. Contractile responses could not be elicited, even though we could show the existence of a-adrenergic and peptide receptors. Responses to any muscle contractile agents, including carbachol and potassium chloride, could not be found in blacklip abalone, Haliotis rubra (Leach). Histology confirmed the relative absence of muscular layers in all the tissues of the gut, indicating that previous literature reports of muscular involvement in contractile movement of gut contents did not appear to apply to this species.
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