• Volume 12, Issue 2

      June 1987,   pages  87-164

    • Amino acid sequence of the fetal chain of yak haemoglobin

      R Lalthantluanga G Braunitzer

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      The amino acid sequence of the fetal chain of yak haemoglobin was determined. The sequence is the same as that of the fetal chain of bovine haemoglobin. Phenylalanine is present at position 12 of the helix A in the fetal chain while tryptophan is the amino acid at this position in theβ-chain of yak adult haemoglobin. This amino acid replacement may be responsible for the higher oxygen affinity of yak fetal haemoglobin than yak adult haemoglobin.

    • Estimation of daily sperm production in rats and monkeys

      K Gopalkrishnan S Kholkute T C Anand Kumar

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      Daily sperm production in rats and monkeys were estimated by extended histometric method. Individual seminiferous tubules were separated, fixed, processed and embedded. Semi-thin sections were stained with toluidine blue and the different cell types quantitated with Chalkley’s eye piece. The daily sperm production estimated was compared with that obtained by the homogenization method. The results indicate that daily sperm production obtained by both the methods were comparable. The present histometric method has an added advantage of requiring very small amount of biopsy material to give precise daily sperm production estimations.

    • Ontogeny of the enzymes related to γ-glutamyl cycle in the human fetal system

      Kathakali De (Addya) Chhabi Dutta Diptis Sengupta

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      Measurements have been made of the enzymes associated with γ-glutamyl cycleviz, γ-glutamyl transpeptidase, γ-glutamyl cysteine synthetase, and 5-oxoprolinase in human fetal brain, liver and kidney over 12–36 weeks of gestation. γ-Glutamyl transpeptidase activity increases gradually with age. γ-Glutamyl cysteine synthetase and 5-oxoprolinase show biphasic pattern of development in human fetal brain. The data presented in this communication may indicate a relationship between γ-glutamyl cycle and amino acid transport.

    • Rhizobium strains expressing uptake hydrogenase in different host species of cowpea miscellany

      K R Dadarwal S S Sindhu H R Sharma

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      Uptake hydrogenase activity in nodules of green gram (Vigna radiata (L.) (Wilczek)), black gram (Vigna mungo (L.) (Hepper)), cowpea (Vigna unguiculata (L.) and cluster bean (Cyamopsis tetragonoloba (L.) (Taub.)), formed with two Hup+ (S24 and CT2014) and one Hup (M11)Rhizobium strains, was determined at different levels of external H2 in air atmosphere. Nodules of all the 4 host species formed by inoculation with strains S24 and CT2014, showed H2 uptake but not those formed with strain M11. H2 uptake rates were higher in 1 and 2% H2 in air atmosphere (v/v) than at 5 or 10% levels in all the host species. Variations in the relative rates of H2 uptake were observed both, due to host species as well as due toRhizobium strains. However, no host dependent complete repression of the expression of H2 uptake activity was observed in nodules of any of the host species formed with Hup+ strains.

    • Mechanism of hypocholesterolemic action of glucagon

      P Jaya P A Kurup

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      The mechanism of hypocholesterolemic action of glucagon was studied in rats. A single injection of glucagon resulted in decreased synthesis of hepatic cholesterol, decreased release of lipoproteins into the circulation and increased degradation of cholesterol to bile acids in the liver. Lipoprotein lipase activity of the extrahepatic tissues was not affected.

    • Cloning and characterization of a DNA repair gene inHaemophilus influenzae

      Rohinee P Kanade N K Notani

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      Using a high-efficiency DNA cloning vector pJ1–8, a DNA repair geneuvr1 has been self-cloned in bacteriumHaemophilus influenzae. Chimeric plasmid pKuvrl, carrying wild type allele ofuvr1 gene and flanking DNA sequences, specifically complements auvr1 gene mutation in the bacterial chromosome. Auvr1} mutation could be transferred from chromosome byin vivo recombination to pKuvr1 and isolated and designated as plasmid pKuvrl. Plasmid pKuvrl carries a 11.3 kb chromosomal DNA insert which was scanned for the presence of any other DNA repair genes by a novel method of directed mutagenesis. Preliminary analysis of the 3 new mutants isolated by this method supports the notion that the insert contains more than one gene concerned with ultraviolet radiation-sensitivity.

    • An enzymic method for the determination of chitin and chitosan in fungal cell walls

      C Subramanyam S L N Rao

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      The free and N-acetyl glucosamine contents, serving as a measure of the amounts of chitosan and chitin respectively, were determined in the chitinase hydrolysates of the cell wall of a wild strain ofNeurospora crassa. Chitinase, obtained from cultures ofSerratia marcescens, could hydrolyse the cell wall completely apart from being capable of hydrolysing preparations of chitin and chitosan. The free and N-acetyl glucosamines, released by chitinase hydrolysis, were determined by a modified Morgan-Elson reaction carried out in the presence and absence of acetic anhydride. The method is capable of estimating chitin and chitosan contents in as little as 100 μg of cell wall material.

    • Use of the plasmid pRK 2013 as a vehicle for transposition inAzotobacter vinelandii

      S H Phadnis H K Das

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      Plasmid stability inAzotobacter vinelandii has been determined and a way to introduce transposon into these cells using the plasmid pRK 2013 has been devised. Transposition of both Tn3 and Tn10 has been attained.

    • Investigations on the mechanism of hypercholesterolemia observed in copper deficiency in rats

      P Valsala P A Kurup

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      The mechanism of hypercholesterolemia effect of Cu2+ deficiency was studied in rats. There was increased activity of hepatic hydroxymethylglutaryl-coenzyme A reductase and increased incorporation of labelled acetate into free cholesterol of liver in the Cu2+ deficient rats. Incorporation of label into ester cholesterol was however decreased in the liver. Concentration of bile acids in the liver was not significantly altered. Increase in the incorporation of labelled acetate into serum cholesterol and increase in the concentration of cholesterol and apo B in the low density lipoproteins + very low density lipoproteins fractions were observed. Activity of lipoprotein lipase of the extrahepatic tissues decreased in the Cu2+ deficient rats.

    • Influence of capsaicin, curcumin and ferulic acid in rats fed high fat diets

      M R Srinivasan M N Satyanarayana

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      Three compounds capsaicin, curcumin and ferulic acid showing hypolipidemic activity have been tested in adult Wistar rats fed high fat diets. Capsaicin (0.20 mg%) fed to female rats along with a 30% saturated fat diet lowered the rate of weight gain, liver and serum triglycerides. In male rats it lowered only the liver and serum total and very low density and low density lipoprotein triglycerides whether fed continuously for 13 or 8 weeks after interchanging the control and test diets from the 5th week onwards. Capsaicin fed to female rats in 30% mixed fat diet increased the rate of weight gain, lowered liver and serum triglycerides, lowered adipose tissue lipoprotein lipase, elevated the hormone sensitive lipase and serum free fatty acids. Capsaicin in 30% saturated fat diet lowered both the enzyme activities to a much lesser extent. Curcumin and ferulic acid (both at 25 mg%) in 30% saturated fat diet tended to lower the rate of weight gain, liver total lipids and serum triglycerides. It is of significance that a common dietary compound ‘capsaicin’ in the range of human intake triggers lipid lowering action in rats fed high fat diets.

    • Mathematical models for optimizing tumour radiotherapy. I: A simple two compartment cell-kinetic model for the unperturbed growth of transplantable tumours

      K Bhaumik V K Jain

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      Tumour growth kinetics has been analysed on the basis of interactions between two compartments comprising the proliferating and non-proliferating cells. Starting from the differential equations of growth of the cell-populations in the two compartments and assuming the process of intercompartmental cell transfers to be linear, an analytic expression on the variation of growth-fraction with the age of the tumour is obtained. The restricted conditions on the cell-cycle time and cell-loss-rate, under which these differential equations lead to a Gompertzian growth of the tumour, are critically analysed. The formalism permits the estimation of some important cell-kinetic parameters, like growth-fraction or cell-loss-factor, from a knowledge of the tumour-growth curve, cell-cycle-time and a single measurement of the cell-loss-rate of the matured tumour, provided the tumour follows a Gompertzian growth. The validity of the model has been verified with the experimental data on 4 different transplantable murine tumour systems. Usefulness of the model has been demonstrated by making some interesting predictions regarding the radiation response of the tumours from the cell-kinetic parameters.

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