• P Shahul Hameed

      Articles written in Proceedings – Animal Sciences

    • pH and dissolution of crystalline style in some bivalve molluscs of Porto Novo coastal waters

      P Shahul Hameed

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      A comparative study of the pH of crystalline style, digestive diverticula and stomach fluid in six bivalve species,Anadara rhombea, Crassostrea madrasensis, Meretrix meretrix, M. casta, Katelysia opima andDonax cuneatus revealed that the digestive diverticula are more acidic while crystalline style is either slightly acidic or nearly neutral. The significance of this finding is discussed. In vitro dissolution of crystalline style of all the six species in buffer solutions of varying pH from 3·6 to 9·0 was observed and the study indicated that the optimum pH for style dissolution is around 8·0 in all species exceptingDonax cuneatus where some dissolution was recorded only at pH 9·0. Based on the physical changes observed in the style, a mechanism of style dissolution has been put forward.

    • Quantitative analysis of carbohydrases in the crystalline style of some intertidal bivalve molluscs

      P Shahul Hameed A L Paulpandian

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      Amylase activity in different pH ranging from 3·6 to 8·0 and activity of sucrose, maltose, trehalase, raffinase, lactase, glycogenase, pectinase, chitinase, carboxy methyl cellulase and cellulase at their respective optimum pH were quantitatively estimated in the crystalline style of intertidal bivalves,Crassostrea madrasensis, Meretrix meretrix, Meretrix casta, Katelysia opima andDonax cuneatus. Amylase was the most active among all enzymes tested. A maximum activity of 137·5 μg/mg/h was recorded in the style ofKatelysia opima while the activity was minimal inDonax cuneatus (39·3 μg/mg/h). Two pH optima were recorded for style amylase ofCrassostrea madrasensis (6·0 and 6·8) andKatelysia opima (5·6 and 6·8). But the activity was higher at higher optimum pH. The enzymes hydrolysing oligosaccharides were weak in most cases or absent. The enzymes acting on reserve polysaccharides such as amylase and glycogenase showed maximum activity in the species tested. However the activity of enzymes degrading structural polysaccharides such as cellulase, carboxy methyl cellulase, pectinase and chitinase was either at a low level or absent. The role of the style enzymes in the extracellular digestion of bivalves is discussed.

    • Feeding and extracellular digestive rhythms in some intertidal bivalve molluscs

      P Shahul Hameed A L Paulpandian

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      The tidal rhythms for changes in morphology, length, dry weight and protein content of the crystalline style are studied in two venerid clams,Meretrix meretrix andKatelysia opima and in a donacid clam,Donax cuneatus. In the two venerid clams the style is housed in a sac conjoined with midgut and there is a tidal rhythm of feeding and extracellular digestion involving a partial dissolution of the style in the ebb tide and reformation in flood tide. But in the donacid clam where the style sac is completely separated from midgut, no detectable changes in the style parameters are recorded during a tidal cycle. However, the rhythmicity in feeding activity is indicated, by the presence of ‘mudcap’ and food particles in the style during flood tide and their subsequent absence during ebb tide. Hence the tidal rhythm of feeding and digestion inDonax cuneatus may be without corresponding changes in the crystalline style. Also this study throws light on the mode of style dissolution.

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