• Volume 10, Issue 1

      March 1986,   pages  1-170

    • Mitochondrial RNA metabolism during mitochondriogenesis in yeast

      Nithyakalyani Raghavan J Jayaraman

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      Mitochondrial transcription has been studied as a function of mitochondriogenesis in yeast cells. Two systems have been used: synchronously growing cells and cells subjected to glucose repression followed by derepression. Maximal RNA synthesis has been found in the S phase of the cell cycle and during the ‘repressed’ phase in asynchronous cells. Activities of RNA polymerase, poly A polymerase and incorporation of [32P]-into RNAin vitro are maximal at the same period. Gel analysis reveals the presence of some high molecular weight RNA species which are likely to be precursors. When chase experiments are carried out in the presence of excess glucose, the high molecular weight species remain unaffected, suggesting that RNA processing may be an important site of action of glucose repression

    • Guggulsterone induced changes in the levels of biogenic monoamines and dopamineβ-hydroxylase activity of rat tissues

      Madhulika Srivastava Narinder K Kapoor

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      The effect of lipid lowering agent, guggulsterone, the purified fraction of guggulipid, on biogenic monoamine levels and dopamineβ-hydroxylase activity of rat brain and heart has been studied. Administration of guggulsterone caused inhibition of brain dopamineβ-hydroxylase activity with marked stimulation in heart bothin vivo andin vitro. The levels of catecholamines were similarily affected. The contents of serotonin and histamine were found to be enhanced in brain and decreased in heart. Alterations in biogenic amines and dopamineβ-hydroxylase activity may be one of the possible mechanisms for the antilipaemic effect of the compound

    • Biochemical lesions in liver and kidney after caecal amoebiasis in rats byEntamoeba histolytica and their reversal by antiamoebic drugs

      P Bardhan I Bansal B N K Prasad S K Sharma N K Garg

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      Levels of lipid peroxides in rat caecum, blood, liver and kidney and the capacity of tissue homogenates to form lipid peroxidesin vitro was enhanced after caecal amoebiasis in rats produced byEntamoeba histolytica (IB-1). The activity of hepatic drug-metabolizing enzymes in post-mitochondrial fraction and the cytochrome P450 contents in microsomal fraction decreased significantly, while lysosomal enzymes such as acid phosphatase, acid ribonuclease and cathepsin B showed an increase in the liver homogenates of infected animals. These changes were reversed following treatment with the antiamoebic drug, metronidazole

    • Effect of chronic choline availability on lung and lymph nodes of rat

      Anand P Sahu Raj K Upreti

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      Male albino rats were given intraperitoneal injections of choline chloride (0. 1,0.33 or 0.5 × lethal dose 50) for a total period of one month and then killed at the end of 30,90 and 240 days for the study of pathotoxicokinetics of choline. Chronic choline administration in rats caused a decrease in growth rate, a dose dependent modulating effect on the somatic tissue indices of lung and lymph nodes, as well as cellularity of lymph nodes. In another experiment, the effect of choline on mica induced pulmonary lesions was studied. The combined effect of choline and mica caused adenocarcinoma of bronchiolar epithelium and marked lymphadenopathy with abnormal cells in the lymph nodes at the termination of experiment (330 days). The results of the present investigation suggest that excess choline availability not only produces pulmonary pathological lesions by itself but it also further enhances the lung lesions in altered pulmonary conditions

    • Large scale production and characterisations of dihydrofolate reductase from a methotrexate-resistant human lymphoid cell line

      Aftab Alam

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      Dihydrofolate reductase has been purified from a methotrexate-resistant human lymphoid cell line (CCRF/CEM-R3) and up to 1 mg of enzyme has been obtained from 5 litres of culture. The enzyme has a molecular weight of 22000 ±500 as determined by gel filtration. The pH activity profile shows a single optimum at pH 7.7, where marked activation is observed by addition of 0.2 M NaCl. TheKm for NADPH is 3μM and dihydrofolate 0.7μM. The binding constant for the inhibitor, methotrexate, is 29 pM

    • Influence of starvation, Triton WR-1339 and [131I]-human serum albumin on rat liver lysosomes

      P Harikumar V Ninjoor

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      The response of rat liver lysosomes to starvation and administration of lysosomotropic agentsviz. Triton WR-1339 and [131I]-human serum albumin, was assessed in terms of their distribution pattern after isopycnic sucrose density gradient centrifugation. Starvation induced changes in lysosomes appeared to be similar to that produced by the detergent uptake. Both the treatments caused a distinct decline in the equilibration densities of the organelles. On the other hand, injected labelled protein failed to comigrate with the lysosomal markers in starved as well as Triton treated rats and conspicuously remained in a region of high specific gravity in the gradient. These findings indicate retarded fusion between secondary lysosomes and [131I]-human serum albumin containing phagosomes in the livers of rats subjected to starvation or detergent treatment

    • γ-Protein, a sulphur amino acid rich protein from pigeon pea (Cajanus cajan (L.) Millsp.)

      T G Krishna C R Bhatia

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      A globulin protein comparatively rich in sulphur amino acids has been isolated from the seeds of pigeon pea. This protein termed γ-protein has a sedimentation coefficients of 7S and a molecular weight of about 90,000. Antibodies were raised against pure γ-protein. Using rocket immunoelectrophoresis it was observed that γ-protein was synthesised in the developing seeds, 21 days after flowering

    • The effect of luteinizing hormone releasing hormone and anti-luteinizing hormone releasing hormone antibodies on chorionic gonadotropin and progesterone secretion by human placental villiin vitro

      A Malik S Kaul C Das

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      Gonadotropin releasing hormone has been located and found to be secreted by the human placenta in culture. Addition of the releasing hormone upto 1μg concentration in the placental cultures brings about stimulation of chorionic gonadotropin and progesterone secretion. Higher amounts of the decapeptide has an inhibitory influence on both the gonadotropin and the steroid production. The action of the releasing hormone on the placenta could be blocked by the anti-luteinizing hormone releasing hormone monoclonal antibodies indicating a possible site of action of the antibodies for control of fertility

    • Prostaglandin-synthetase activity in developing toad ovary—I. Detection and properties

      Shyamali Mukharjee Dhruba Maitra Parul Chakrabarti

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      Prostaglandin-synthetase activity has been measured in the microsomal fraction of developing toad (Bufo melanostictus) ovary using arachidonic acid as the substrate. Indomethacin (0.74μM) and aspirin (0.35μM) inhibit this activity. The activity is maximum in immature ovary and its level gradually decreases with maturity of the organ till the breeding season arrives, when it rises again. Time course study shows that the activityin vitro becomes steady after 3 min of incubation in all the cases, except the immature ones in which it sharply declines. Soluble supernatant was found to contain some inhibitory factor(s), which is partially inactivated by heating at 100°C for 5 min (∼ 43%). Intraperitoneal injection of equine luteinizing hormone stimulates this enzyme activity in the mature ovary during non-breeding season. This suggests that similar to mammalians prostaglandin-synthetase, the toad ovary enzyme is also regulated by luteinizing hormone

    • DNA binding proteins of rat thigh muscle: Purification and characterization of an endonuclease

      A R Augustina Rajakumar G Shanmugam

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      Two major DNA binding proteins of molecular weights 34,000 and 38,000 have been identified in the 30,000 g supernatant (S-30) fraction of rat thigh muscle extracts. The presence of 38 KD DNA binding protein in the muscle S-30 could be demonstrated only if Triton X-100 treated extracts were used for Afinity chromatography suggesting that this protein may be a membrane associated DNA binding protein. The 38 KD DNA binding protein differed from the 34 KD DNA binding protein also in its chromatographic behaviour in DE-52 columns in which the 38 KD protein was retained, while the 34 KD protein came out in the flow-through in an electrophoretically pure form. The 34 KD DNA binding protein can also be purified by precipitation with MgCl2. Incubation of 0 15 M NaCl eluates (containing the 38 KD and/or 34 KD DNA binding protein) in the presence of 100 mM Mg2+ resulted in the specific precipitation of the 34 KD protein. Prolonged incubation (30 days) of the 0.15 M NaCl eluates containing the two DNA binding proteins at 4°C led to the preferential degradation of the 34 KD DNA binding protein. Nitrocellulose filter binding assays indicated selective binding of purified 34 KD protein to ss DNA. Purified 34 KD DNA binding protein cleaved pBR 322 supercoiled DNA, and electrophoresis of the cleavage products in agarose gels revealed a major DNA band corresponding to the circular form of DNA.

    • The nature of lectins fromDolichos lablab

      N Siva Kumar D Rajagopal Rao

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      The lectins from the seedsof Dolichos lablab var.lignosus (field bean) andDolichos lablab var.typicus (lablab bean) have been isolated in a homogeneous form by affinity chromatography on D-mannose linked Sepharose. Both the lectins are glycoproteins and have a molecular weight of 60,000 andS20,w value of 5.2 and seem to be made up of 4 similar subunits (apparent molecular weight 15,000). The carbohydrate content ofthe lectins is mostly fucose (2–5 mol per mol of protein), mannose (5–8 mol per mol of protein) and N-acetyl glucosamine (1–2 mol per mol of protein). The amino acid composition of both the lectins was similar and methionine and half cystine could not be detected, Both the lectins have similar tryptic peptide map. Alanine and serine were the only N and C-terminal amino acids for both lectins. The lectins were found to contain low amounts of bound metals such as manganese, magnesium and calcium. The near ultra-violet circular dichroism spectra of the lectins are similar to that of Sainfoin. Circular dichroism data indicate that tyrosine and tryptophan residues are involved in sugar binding.

      The lectins are nonspecific for human blood groups and they agglutinate a variety of other erythrocytes. Among a number of sugars, D-glucose and D-mannose inhibited the haemag-glutinating activity ofthe lectins. The lectins were antigenically similar

    • A new method of measurement of permeability of lipid membranes

      P Radhakrishnamurty S Sheela Santhakumari

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      A new method, based on potential measurements to obtain permeabilities and mobilities of ionic species passing through membranes, under the influence of concentration gradients is proposed. This method is applied to three different lipid membranes in aqueous KCl solutions. The values of permeabilities and mobilities obtained by this simple method is in good agreement with those reported in literature

    • Preformed messengers inMicrosporum canis macroconidia

      N Banumathi B M Jayaram G Ramananda Rao

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      Macroconidia ofMicrosporum canis, when placed in a nutrient medium produce germ tubes within 4–6 h. Precursor incorporation studies showed that protein synthesis occurred prior to RNA synthesis. Sucrose density gradient analysis of wet and dry spore extracts revealed the presence of 16 % and 11 % polysomes respectively. The polysomal content increased to about 50% within 15 min of germination. Synthesis of RNA occurred only after 2 h of germination. Pool equilibration of the radioactive precursors was not limiting to these measurements. Polyadenylated RNA was isolated from macroconidia and was found to comprise 2–2.5 % of the total RNA. The poly(A)+ RNAs were heterodisperse and translatable in a wheat germ cell free translating system. It was concluded that macroconidia ofMicrosporum canis contain pre-formed mRNA which is translated early in germination

    • In vitro tests for screening of immuno-modulating mycobacterial strains in leprosy

      T J Birdi P R Salgama H Bharucha N H Antia

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      There is an urgent need for the development of anin vitro assay for the initial screening of a large number of organisms from which potential candidates as vaccines can be identified. Our previous studies have demonstrated a crucial defect in the lepromatous macrophage. In this study by monitoring this defective macrophage response we have screened various mycobacteria for their ability to reverse the alterations induced byMycobacterium leprae. Among the limited Mycobacteria testedMycobacterium vaccae appears to be the most promising as an immunomodulator. Our results also indicate the need for caution in using the mouse model for this purpose

    • Minimum inhibitory concentration of drugs againstMycobacterium leprae as determined by anin vitro assay

      R Jagannathan P R Mahadevan

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      The observations that liveMycobacterium leprae after entry into cultured peritoneal macrophages from mice, reduced the EA rosetting macrophages, have been exploited to determine the minimum inhibitory concentration of diamino diphenyl sulphone and rifampicin. Diamino diphenyl sulphone showed a minimum inhibitory concentration of 0.028 μg/ml and rifampicin 0.11μg/ml when given externally. However, there was accumulation of diamino diphenyl sulphone inside the macrophages. At an external concentration of 0.028 μg/ml the concentration inside the macrophage was 0.5μg/ml. The minimum inhibitory concentration for diamino diphenyl sulphone in this assay system is higher by several folds and that for rifampicin is slightly lower, than what is reported earlier with mice foot pad experiments. The minimum inhibitory concentration reported in this assay system is quite close to what is observed forin vitro inhibition ofMycobacterium lufu with both the drugs

    • Mechanism of action of aflatoxin B1

      R P Tiwari T C Bhalla S S Saini G Singh D V Vadehra

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      The inhibitory effects of aflatoxin B1 were found to be related to the gram character in procaryotes, used in this study. Ethylene diamine tetra chloroacetic acid (0.05% w/v) or Tween-80 (0.05 % v/v) addition accentuated the aflatoxin B1 growth inhibition inSalmonella typhi andEscherichia coli at different pH values. The inhibition of lipase production was only 5–20 % inPseudomonas fluorescence ca. 25–48% inStaphylococcus aureus andBacillus cereus at different aflatoxin B1 concentrations (4–16μg/ml).However, inhibition of α-amylase induction was complete in1Bacillus megaterium whereas the inhibition was partial inPseudomonas fluorescence (27–40%) at 32μg aflatoxin B1 concentration. An increase in leakage of cell contents and decreased inulin uptake were observed in toxin incubated sheep red blood cell suspension (1 %) with increased aflatoxin B1 concentration

    • Transmission of male recombination, segregation distortion and sex-ratio imbalance inDrosophila melanogaster

      Gurbachan S Miglani Vindhya Mohindra

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      From the first test cross progenies of control (no larval transfers; no ethyl methanesulphonate), physical stress (two larval transfers; no ethyl methanesulphonate) and 0.75% ethyl methanesulphonate (two larval transfers; 0.75% ethyl methanesulphonate)-treated F1 (Oregon K +/dumpy black cinnabar, dp b cn) males ofDrosophila melanogaster, respectively, 6,10 and 52 wild-looking first test cross males were again test crossed to obtain second generation. The overall percentages of male recombination detected in the second test cross progenies, in the three sets of experiments, were statistically the same as those in the first test cross progenies. Thus the enhanced male recombination caused by physical stress (with or without ethyl methanesulphonate) was transmitted to next generation. Non-reciprocal male recombination was observed indp b but not inb cn region in both first and second test cross progenies. Three abnormalities, (i) production of wild-type flies in majority overdp b cn type, (ii) Non-Mendelian segregation atdp b andcn loci and (iii) sex-ratio differences fordp bcn and +b cn types observed in test cross progenies of F1 males ofDrosophila melanogaster were transmitted to next generation when induced with 0.75 % ethyl methanesulphonate but not when these abnormalities were induced with physical stress. The data suggest possible association of non-reciprocal male recombination, segregation distortion and sex-ratio imbalance inDrosophila melanogaster. In fact these may be representing different aspects of the same phenomenon

    • N-[2-Naphthyl]-glycine hydrazide, a potent inhibitor of DNA-dependent RNA polymerase ofMycobacterium tuberculosis H37RV

      Rekha Prabhu G Ramananda Rao M Jamaluddin T Ramakri Shnan

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      N-[2-Naphthyl]-glycine hydrazide has been shown for the first time as a potent inhibitor of the DNA-dependent RNA polymerase (EC 2.7.7.6) ofMycobacterium tuberculosis H37Rv. At a concentration of 10-9 M, the compound shows maximum inhibition of the enzyme, the inhibition being less at higher concentrations. It is suggested that the novel type of inhibition pattern may be due to hydrophobic interactions occurring between the molecules of the compound at higher concentrations. The finding that there is a shift in the λmax of the compound could also account for this phenomenon. The effect of this compound was also tested on DNA-dependent RNA polymerases from an eukaryotic fungus,Microsporum canis. At a concentration of 10−9 M it inhibits RNA polymerase II (32%) but not RNA polymerasesI andIII

    • Antifertility effect of tamoxifen as tested in the female bonnet monkey (Macaca radiata)

      N Ravindranath N R Moudgal

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      The administration of a potent antiestrogen, tamoxifen at a dose of 3 mg/kg body weight/day orally post-coitally to cycling mated bonnet monkeys(Macaca radiata) from days 18–30 of cycle resulted in inhibition of establishment of pregnancy in 9 out of 10 monkeys. Tamoxifen effect was not due to interference with luteal function. The effect was specific to tamoxifen as exogenously administered progesterone could not reverse it. In addition to suggesting a role for estrogen in maintenance of early pregnancy in the primate the present study could be a prelude to the development of an effective post-ovulatory approach for regulation of fertility in the human female

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