• Volume 2, Issue 2

      June 1980,   pages  87-162

    • Adaptation to salinity by fish: Alterations in energy transducing status of muscle mitochondria

      Indu Bashyam Suresh Narayan J Jayaraman

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      The functional status of fish muscle mitochondria during exposure of the organism to salinity stress was studied. No alterations were observed in the substrate oxidation capacity. However, the mitochondria appear to be in an uncoupled state during the first few days of exposure and recover thereafter. This could be correlated to high endogenous Ca2+ levels in the mitochondria in the early period. A Na+-Ca2+ antiport in these mitochondria is shown. Evidence is also presented to show that the mitochondria isolated during the early stages of stress are in a swollen state and are unable to contract on addition of ATP and Mg2+ Continued exposure to the stress, however, reverses the situation.

    • The role of free amino groups of peptides and proteins in the Folin-Lowry and biuret methods

      B R Srinivasa L K Ramachandran

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      On an equal weight basis polymyxin B and EM 49 which do not contain tyrosine or tryptophan yielded the same colour intensity as proteins in the Folin-Lowry and biuret methods. But, in the absence of reagent C (alkaline copper reagent) polymyxin B and EM 49 yielded no colour in the Folin-Lowry method. Mono-, di- and tri-formyl polymyxins B formed identical amounts of coloured complexes as polymyxin B in the two methods. However, the tetra- and penta-formyl polymyxins B yielded only one-fifth and one-sixth, respectively, of the expected colour in the Folin-Lowry method. Similarly, 40% and 30%, respectively, of the anticipated amount of colour is formed in the biuret method. Formylated and methylated lysozyme and bovine serum albumins form only 70–75% of the expected colour in the Folin-Lowry method. Since formation of colour by reduction of Folin reagent, in the Folin-Lowry method, is at least partly due to complexes of copper, it was inferred that polymyxin B as well as its mono-, di- and tri-formyl derivatives on the one hand and the tetra- and penta-formyl derivatives on the other differ in their ability to complex Cu(II) The former group of compounds was indeed found to complex as many as three Cu(II) ions whereas the tetra- and penta-formyl polymyxins B complexed only one equivalent, under conditions of excess Cu(II). Under conditions of low Cu(II), polymyxin B and all its derivatives complexed only one Cu(II). In proteins, sites other than amino groups which complex Cu(II) probably play a major role in the reduction of the Folin reagent, since methylated lysozyme and bovine serum albumin yield 70–75% of the colour formed by the unmodified proteins in the Folin-Lowry reaction.

    • On the regulation of L-hydroxyproline dissimilatory pathway inPseudomonas aeruginosa PAO

      T Herbert Manoharan

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      The enzymes involved in the regulation of L-hydroxyproline degradation inPseudomonas aeruginosa PAO were investigated. L-hydroxyproline when present in the growth medium induces all the four enzymes in the pathway. Growth of the cells in L-proline also weakly induced the enzymes. The organism failed to utilize D-allo-hydroxyproline due to permeability factors. Mutants blocked in the oxidative pathway of L-hydroxyproline were isolated and enzymatically characterized. In all the mutants lacking any one of enzymes of the metabolic pathway, L-hydroxyproline is still active in inducing the remaining enzymes of the pathway suggesting that L-hydroxyproline has intrinsic inducer activity.

    • Synthesisin vitro of cholesterol by mitochondria in the shrimpPenaeus aztecus (Ives)

      R V Krishnamoorthy G J Lakshmi A Venkataramiah

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      The incorporation of [14C]-acetate, [14C]-mevalonate and [14C]-desmosterol into cholesterol in the muscle mitochondria of the brown shrimpPenaeus aztecus (Ives) is more as compared to that in hepatopancreas. [14C]-Desmosterol is more efficiently incorporated into cholesterol in comparison with [14C]-acetate. The muscle mitochondria from males incorporated more [14C]-mevalonate into cholesterol than those from females, while the converse is true in the hepatopancreatic mitochondria.

    • In vitro hemolytic activity ofPlasmodium berghei on red blood cells

      Sudhir Gupta K C Saxena

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      A suspension ofPlasmodium berghei obtained by lysis with saponin of red blood cells from an infected rat showed high hemolytic activity, when incubatedin vitro with normal rat red blood cells. The hemolysis was a temperature-dependent process and was dependent on the concentration of the parasite. Plasma ofPlasmodium berghei infected albino rats also possessed lytic activity.

    • Effect of sciatectomy and induced ammonia stress on Mg2+_adenosine triphosphatase activity in frog tissues

      C Sreeramulu Chetty R Chandramohan Naidu K S Swami

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      Mg2 + dependent —adenosine triphosphatase activity has been studied in the muscle, brain, kidney and liver tissues of frog,Rana hexadactyla (Lesson) after sciatectomy and induced chronic ammonia stress. The enzyme activity decreased in the tissues of the denervated frog. The activity of the enzyme increased in all the tissues of the normal and denervated frogs except in the denervated muscle when ammonium lactate was infused intraperitoneally.

    • Effects of dynamic impacts on human bones

      Meera Ramrakhiani D Pal T S Murthy

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      Flat bones of human skeleton were subjected to dynamic indentation with ball indenters. The impacted surface was studied under high magnification and also by using the technique of multiple beam interferometry. The impulse caused the pile up of material at a little distance from the edge of the indent. The diameter of indent is found to increase as fourth root of the energy of impact. Bone structure also has the tendency to minimize the damage caused by external forces. There was about 90% recovery in deformation in the depth of indents due to internal stresses created inside the bone by the impact.

    • Proteins of the brain and body wall in larvae ofDrosophila melanogaster

      Sheela U Donde Obaid Siddiqi

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      Proteins of the brain and body wall cells of third instar larvae ofDrosophila melano-gaster have been examined by two-dimensional gel electrophoresis. Out of over 600 [35 S ]-labelled peptide spots seen in brain or body wall extracts, 517 were common to both; 61 spots were unique to brain and 66 unique to muscle. Glycoproteins were identified by soaking the gels in radioactive iodinated Concanavalin-A. Forty four Con-A binding glycoproteins were identifiable in the brain and 41 in the muscle extracts. Out of these, 8 glycoproteins of the brain and 8 of muscles appear to be tissue-specific.

    • Effect of copper intrauterine contraceptive device on carbohydrate metabolism in rat endometrium

      Rakesh K Johri P R Dasgupta

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      Activities of Phosphorylase, glyceraldehyde-3 -phosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase and succinate dehydrogenase in the rat endometrial tissue are significantly inhibited by an intrauterine copper device, while it stimulated glucose-6-phosphate dehydrogenase activity. The copper device decreased the lactate/pyruvate ratio in the tissue; pyruvate utilizationin vitro by the rat endometrium is also blocked by copper. These findings suggested that the normal carbohydrate metabolism of the tissue may be affected in presence of copper, thus resulting in a change of the endometrial function, which may be one of the factors responsible for the contraceptive and pharmacological action of an intrauterine copper device.

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