• S K Sarangi

      Articles written in Proceedings – Animal Sciences

    • Studies on the silk gland ofBomhyx mori: A comparative analysis during fifth instar development

      S K Sarangi

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      Middle and posterior parts of the silk gland of fifth instar bivoltine and multivoltine races ofBombyx mori and their hybrid were analysed for the concentration of fibroin, DNA, RNA and total protein. Fibroin content of the silk gland increased rapidly from the beginning of fifth instar upto the spinning stage. Concentration of DNA in the middle silk gland was maximum at 24 hr and decreased thereafter. In the posterior silk gland, the concentration of DNA increased upto 72 hr and then decreased, RNA concentration was maximum at 72 hr and 120 hr, in the middle and posterior silk gland respectively. The total protein content increased gradually upto the spinning stage in the middle silk gland whereas it increased upto 120 hr and decreased sharply thereafter in the posterior silk gland. The difference in the concentration of these constituents in the silk gland was correlated with the differential silk output in both the pure races and their hybrid.

    • Alkaline protease in the midgut of the silkwormBombyx mori L: changes during metamorphosis

      S K Sarangi

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      The protease activity in the midgut of bivoltine and muitivoltine races of the silkworm,Bombyx mori, was studied. The enzyme activity increased during fifth instar reached a peak, and decreased significantly through pre-pupal stage to the lowest level at the pupal stagTouring pharate adult period, the protease activity increased to reach another peak just before emergence of the moth, and decreased thereafter. The enzyme activity m bivoltmes was about 2–3 times higher than multivoltines at the peak levels. Bivoltines showed a sex difference in midgut protease activity while no significant difference was observed in multivoltines. Larvae and pharate adults showed a difference in the pH optima for the enzyme activity. From the results the possible role of midgut protease during the process of metamorphosis is discussed.

    • Sodium coupled nutrient transport in the midgut tissue of the silkworm,Bombyx mori L.

      M V V Subramanyam S K Sarangi

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      Fifth instar larvae ofBombyx mori were administered with additional Na+ ion orally. The concentration of Na+ increased and that of K+ decreased significantly in the haemolymph within 24 h. There was no marked difference in the ionic concentration of the midgut cell while K+ increased in the gut content. The protease activity increased significantly in gut lumen with a resultant increase in amino acid concentration, which showed a decrease in gut tissue and haemolymph. The protein content did not show significant change in gut lumen, while in gut tissue and haemolymph it decreased markedly. The results are discussed in relation to the Na+-linked nutrient transport mechanism in the gut epithelium ofBombyx mori.

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