• S K Roy

      Articles written in Journal of Biosciences

    • Uterine RNA synthesis during protein deficiency and steroidmaintained pregnancy in rats

      R K Singh S K Roy

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      Some aspects of uterine RNA synthesis including [3H]-uridine incorpo ration into RNA, activities of RNA polymerases and ribonucleases were studied. It was observed that both normal and pregnant animals, kept on protein-free diet for 15 and 20 days, showed a significant increase inin vivo uptake of [3H]-uridine into total RNA. Activities of RNA polymerase I and polymerase III increased two-fold in animals kept on a protein-free diet; however, RNA polymerase II activity was unaffected by protein restriction. In animals kept on protein-free diet where pregnancy was maintained by exogenous estrogen and progesterone, specific activity of nuclear RNA was further increased and the activities of RNA polymerases I, II and III markedly increased. Levels of RNase were also increased significantly during protein deficiency, thus showing a rapid turn-over of uterine RNA. These observations indicate that during protein restriction, uterine RNA synthesis is regulated at transcriptional level by a selective stimulation of RNA polymerase and RNase also plays an important role.

    • The binding of progesterone in different parts of the rabbit uterus during implantation

      Raj K Puri S K Roy

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      Progesterone receptors, both nuclear and cytosolic, were determined in the embryonic and inter-embryonic segments of the rabbit uterus at 6, 7 and 8 daypost-coitum. At day6 postcoitum a higher concentration of nuclear receptor in the embryonic segment was observed compared with that in the inter-embryonic segment. A reverse situation was observed in the case of cytoplasmic receptors. On the 7th daypost-coitum, no significant alteration in the concentration of either kind of the receptors was observed. However, on day 8, a higher concentration of both nuclear and cytosolic receptors at the embryonic site was observed compared to that in inter-embryonic segment. Since receptors are influenced only in the immediate vicinity of the blastocyst, it can be suggested that the blastocyst plays a role in the induction of its own implantation. Further, at day 8 increase in receptor concentration at the embryonic site may be related to the presence of decidual tissue at this site.

    • The cytosol receptors for progesterone in the different parts of rabbit fallopian tube and uterus during ovum transport

      Raj K Puri S K Roy

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      Progesterone receptors were determined in the cytosol from the ampulla, ampullaryisthmic junction and isthmus of rabbit fallopian tube and uterus of estrus and pregnant rabbits. The receptor levels when compared among its various anatomical segments, were the same in ampulla, isthums and uterus but maximum in ampullary-isthmic junction. Significant differences were observed in mated animals at 14, 24, 34, 48, 70 and 144 h after coitus. The receptor concentrations in portions of the fallopian tube showed no significant change between 14 and 24 h after coitus, except for a decrease in ampullary-isthmic junction at 24 h. At 34 h the concentration of receptor further decreased in all parts of the tube. At 48 and 70 h after coitus, receptor concentrations decreased gradually in ampulla and ampullary-isthmic junction, while isthmus showed a gradual increase. At 144 h, the receptor concentration showed no further change in ampulla and ampullary-isthmic junction; however, isthmus showed a decline. The uterine receptor concentration declined steadily from estrus till 70 h after coitus, however, it was increased at 144 h. The dissociation constant (Kd) of cytosol receptor in all the tissues at estrus and during early pregnancy was found similar. The implications of these changes in relation to the normal ovum transport have been correlated in this paper.

    • Effect of Centchroman (67/20) and 78/224 on nucleic acid and protein biosynthesis during implantation in rats

      A D Srivastava Sanjeev Ratna S K Roy

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      The biosynthesis of nucleic acids and proteins was studied in rat uterus by following the incorporation of [3H]-thymidine, [3H]-uridineand[14C]-leucinein control and pregnant rats in the presence and absence of two anti-implantation drugs. One of the drugs, 78/224 caused a significant increase in incorporation whereas the other drug, Centchroman, caused an inhibition in incorporation of all the three precursors. The implications of these changes in the light of estrogenicity, agonist and antagonist actions of anti-estrogens have been analysed. The importance of homeostatic mechanisms involved in nucleic acids and proteins for the maintenance of constant internal milieu for blastocyst attachment has been discussed.

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