Department of Biological Sciences
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Item Copper uptake by free and immobilized cyanobacterium(OUP, 1989) Verma, Sanjay KumarCopper uptake in free and immobilized cells of the cyanobacterium Nostoc calcicola has been examined. The immobilized cells invariably maintained a higher profile of Cu intake rate (12.7 nmol mg−1 protein min−1) over the free cells (6.0 nmol mg−1 protein min−1). The total Cu uptake in immobilized cells was almost two and a half-times more than their free cell counterpart under identical experimental conditions. Also, the immobilized cells showed a stronger positive correlation between Cu adsorption and uptake. The results have been discussed in terms of improved metabolic efficiency of immobilized cells.Item Genetic transformation of glutamine auxotrophy to prototrophy in the cyanobacterium Nostoc muscorum(Springer, 1990) Verma, Sanjay KumarItem Evidence for energy-dependent copper efflux as a mechanism of Cu2+ resistance in the cyanobacterium Nostoc calcicola(OUP, 1991) Verma, Sanjay KumarWild-type Nostoc calcicola carried out oxygenic photosynthesis extremely sensitive to copper. A Cu(2+)-resistant mutant (Cu-R1) of the cyanobacterium grew normally at high concentrations of Cu2+. Its ability to grow under such conditions was found to be due to mutational acquisition of an energy-dependent efficient system of Cu(2+)-efflux, which rendered Cu(2+)-inhibited oxygenic photosynthesis fully reversible.Item Glutamate inhibition of aerobic N2-fixation and its regulation by nitrate and ammonium in cyanobacterium Nostoc muscorum(NISCAIR, 1992) Verma, Sanjay KumarItem pH regulation of growth, photosynthesis, glutamine synthetase activity and micronutrient transport in the cyanobacterium Hapalosiphon welwitschii(OUP, 1992) Verma, Sanjay KumarOptima for growth, oxygenic photosynthesis and glutamine synthetase activity occurred at pH 10, thus suggesting that the cyanobacterium Hapalosiphon welwitschii is an alkalophile. It produced a Cu-Zn efflux system at pH 9 or 10, but not at pH 7 or 8, to relieve photosynthesis from Cu or Zn inhibition. This finding has a bearing on the ecophysiological competence of the cyanobacterium under natural conditions.Item Copper toxicity and phosphate utilization in the cyanobacterium Nostoc calcicola(Springer, 1993) Verma, Sanjay KumarItem Multiple metal resistance in the cyanobacterium Nostoc muscorum(Springer, 1995) Verma, Sanjay Kumar