| 1 | Heavy Metal Toxicity in a N_2-Fixing Cyanobacterium, Anabaena doliolum: Regulation of Toxicity by Certain Environmental Factors显示文摘The toxic effects of chromium and tin salts on growth, 14C uptake, heterocyst differentiation, and nitrate reductase. nitrogenase, and glutamine synthetase activities of Anabaena doliolum and their regulation by pH. salinity, extracellular metabolites (spent), and organic acids have been studied. The toxicity of the test metals was lowered at alkaline pH and increased at acidic pH. NaCl at 20 mM was found to decrease metal toxicity. Extracellular metabolites (spent) in a 1:1 ratio(v/v) with fresh culture medium and organic acids were found to reduce metal toxicity. Among the various organic acids studied, humic acid was the most effective in regulating metal toxicity, apparently due to its multiple binding sites for metal cations. This study demonstrated that environmental factors.such as pH, salinity, extracellular metabolites, and organic acids, can mediate the toxicity of heavy metals to A. doliolum in a laboratory microcosm, (C)1990 Academic Press. Inc. | S.K.DUBEY L.C.RAI | 1990 | Biomedical and Environmental Sciences1990，3，2： | 1 |
| 2 | Metal Induced Inhibition of Photosynthesis,Photosynthetic Electron Transport Chain and ATP Content of Anabaena doliolum and Chlorella vulgaris:Interaction with Exogenous ATP显示文摘This study demonstrates a concentration dependent inhibition of carbon fixation,O2 evolution,photosynthetic electron transport chain and ATP content of A.doliolum and C.vulgaris by Cu,Ni and Fe.Although the mode of inhibition of photosynthetic electron transport chain of both the algae was similar.PS Ⅱdepicted greater sensitivity to the test metals used.The toxicity in both organisms was Cu>Ni>Fe.A.doliolum was,however,more sensitive to Cu and Ni,and C.vulgaris to Fe.Toxicity was generally dependent on metal uptake,which in turn was dependent on their concentrations in the external medium.A partial restoration of nutrient uptake,carbon fixation,and enzyme activities following supplementation of exogenous ATP suggests that ATP regulates toxicity through chelation. | NIRUPA MAMALLICK L.C.RAI | 1992 | Biomedical and Environmental Sciences1992，5，3： | 1 |
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