Cationic responses of organs and haemolymph of Biomphalaria pfeifferi (Krauss), Biomphalaria glabrata (Say) and Helisoma trivolvis (Say) (Gastropoda: Planorbirdae) to cationic alterations of the medium |
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Authors: | W. K. Nduku A. D. Harrison |
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Affiliation: | (1) Department of Biology, University of Waterloo, Waterloo, Ontario, Canada;(2) Present address: Department of Zoology, University of Rhodesia, Salisbury |
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Abstract: | The cationic responses of haemolymph, mantle collar, headfoot, gut + digestive diverticulum and ovotestis + albumin gland of three planorbids to cationic changes in the media are explored. Body organs exhibited cationic homeostasis, although attained with difficulty under very low Ca : Mg and Ca : Na ratios. Haemolymph imbalances were obtained at very low calcium concentrations and at very low Ca : Mg and Ca : Na ratios in the medium; this may be linked to competition for Ca2+ uptake sites in the epithelium by Mg2+ and possibly Na+ ions.Fecundity and shell growth in relation to calcium concentrations and to Ca : Mg and Ca : Na ratios are examined.Normal internal cationic levels, under optimal conditions, were obtained for each species. Significant interspecific differences for haemolymph sodium were found; magnesium levels were slightly higher in Biomphalaria spp. than in Helisoma trivolvis; potassium levels were all similar. Amounts of tissue calcium decreased as follows: Mantle collar head-foot ovotestis + albumin gland-gut + diverticulum. Tissue magnesium levels in the gut were low. H. trivolvis had highest tissue calcium and sodium; B. glabrata had highest tissue potassium. |
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Keywords: | Mollusca Planorbidae Hydrobiology Cationic variation Haemolymph Body tissues Biomphalaria Helisoma |
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