Cobalt transport in nickel-resistant strains ofNeurospora crassa |
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Authors: | P. Maruthi Mohan Prof. K. Sivarama Sastry |
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Affiliation: | (1) Department of Biochemistry, Osmania University, 500007 Hyderabad, (A.P.), India;(2) Present address: Department of Biochemistry, Indian Institute of Science, 560012 Bangalore, India |
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Abstract: | Uptake of Co2+ by three nickel-resistant strains (NiR1, NiR2, and NiR3) ofNeurospora crassa that differed in resistance to Co2+ has been studied. Uptake was linear with Co2+ concentration (up to 1 mM), with time (up to 6 h), and with pH between 3 and 6. Uptake rates were in the order NiR2>NiR1>NiR3. In all strains, there was gradual increase in Co2+ uptake between 10° and 28°C, with a much sharper increase between 28° and 40°C. Metabolic inhibitors decreased Co2+ uptake partially in all strains, except for KF in NiR3. About 50–80 g Co2+/100 mg dry weight was surface bound. Ni2+, Zn2+, and Mn2+ competed with Co2+, the effects being strain specific. Mg2+ inhibited Co2+ uptake in all strains with preformed mycelia. In NiR1 and NiR2 only with young mycelia (40 h old) was Mg2+ inhibitory to Co2+ uptake,during growth in the presence of Co2+. The results suggested the presence of two transport systems for Co2+ in NiR1 and NiR2, only one of which was sensitive to Mg2+; in contrast, NiR3 had a single system, which was sensitive to Mg2+. |
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