Chromium toxicity in Neurospora crassa.
Chromium toxicity in Neurospora crassa.
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DOI：
10.1016/0162-0134(94)85040-2
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发表时间：
1994-11
影响因子：
3.9
通讯作者：
V. Ramana;K. Sastry
中科院分区：
文献类型：
--
作者：
V. Ramana;K. Sastry
A comparative study has been made on the mechanisms of toxicities of trivalent and hexavalent forms of chromium inNeurospora crassa. Of the two forms, Cr6+is more toxic than Cr3+. The toxicity of Cr3+was found to be due to its specific antagonism with iron uptake. Fe3+was found to be very effective in reversing the toxicity of Cr3+by concomitantly suppressing its uptake. That the Cr3+toxicity caused a conditional intracellular iron deficiency was indicated by the decrease in the activities of catalase and uricase and a progressive increase in the excretion of iron binding compound into the medium.The toxicity of Cr6+(as Cr2O72−) was found to be due to its specific antagonism of sulfate uptake. Methionine was found to be more effective in reversing dichromate toxicity than sulfate, probably by repressing the synthesis of sulfate permeases responsible for dichromate (Cr6+) uptake. Maximal uptake of Cr6+was nearly tenfold lower and Vmaxmuch higher than that of Cr3+. Evidence has been adduced to show that Cr6+and Cr3+were toxic by themselves and that interconversion between the tri- and hexavalent forms of chromium did not occur to any detectable extent.
