Department of Biological Sciences
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Item Molecular Databases(EMI, 2001) Verma, Sanjay KumarItem Bioremediation of cadmium by metal resistant strain of Cyanobacteria(Scientific Publisher, 2002) Verma, Sanjay KumarItem Secondary metabolite production of cyanobacteria(IK Books, 2009) Verma, Sanjay KumarItem Impact of heavy metals on glutamine synthetase and nitrogenase activity in Nostoc calcicola.(J-Stage, 1987) Verma, Sanjay KumarItem Heavy metal Uptake in the Cynobacterium Nostoc calcicola.(IBS, 1988) Verma, Sanjay KumarThe literature on the inhibitory effect of copper on growth (Les &Walker, 1984), photosynthesis (Shiol et al, 1978) and nitrogen fixation (Rai & Raizada, 1985) in algae and higher plants is impressive. Heavy metals inhibit the uptake and assimilation of nutrients (Singh & Yadava, 1983, 1984). Mechanisms governing the metal uptake process in microorganisms (Bhattacharjee, 1986) and in cyanobacteria (Singh & Yadava, 1985) are investigated. The possibility of involvement of carrier (s) and energy in the metal transport across the cell membranes has been suggested (Veltrup, 1977). The toxicity of heavy metal to algae (Hargreaves & Whitton, 1976 a,b; Singh & were diluted to S hli with triple glass distilled water. A furher Pandey 1981) is influenced by environmental factors like pH, light and complexans. However, there have been only a few studies on the effect of environmental factors on copper uptake in cyanobacteria. The present investigation reports on the copper uptake kinetics and the role of various factors on Nostoc calcicola.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 Factors regulating copper uptake in a cyanobacterium(Springer, 1990) Verma, Sanjay KumarCopper uptake in the diazotrophic cyanobacteriumNostoc calcicola was found to be typically biphasic, comprising rapid binding of the cations to the cell wall (during the first 10 min) followed by the subsequent metabolism-dependent intracellular uptake for at least 1 h, with a curvilinear kinetics saturating at 40 µM (Km 25.0 µM, Vmax 3.0 nmol Cu mg−1 protein min−1). The cellular Cu uptake was light- and ATP-dependent, and the addition of 3(3,4-dichlorophenyl)-1,1-dimethylurea or exogenous ATP proved that the energy to drive Cu transport was derived mainly through PS II reactions. The application of metabolic inhibitors and uncouplers like carbonylcyanidep-nitrofluoromethoxylphenyl hydrazone, N,N′-dicyclohexycarbodiimide, azide, and p-chloromercuribenzoate revealed that -SH group(s), proton gradient across the cell membrane, and ATP hydrolysis were involved in the transmembrane movement of Cu inN. calcicola. While monothiol (2-mercaptoethanol) caused a twofold reduction in Cu uptake rate, dithiol (dithiothreitol) contributed towards a further drop in the cation uptake rate.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 Kumar
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