Contrasting fates of the paraquat monocation radical in Escherichia coli B and in Dunaliella salina.
Anaerobic cultures of Escherichia coli exposed to paraquat (PQ2+) accumulated the corresponding monocation radical PQ+., both within the cells and in the suspending medium. The green alga, Dunaliella salina, which is susceptible to a light- and O2-dependent toxicity of PQ2+, was nevertheless unable to cause accumulation of PQ+. when illuminated anaerobically and could, moreover, discharge the ESR signal and the blue color of PQ+. accumulated by E. coli. Spin trapping allowed demonstration of the photoproduction of O2- within D. salina and of the augmentation of that O-2 production by PQ2+. D. salina appears to contain an electron sink and a heat-labile mechanism for transferring electrons from PQ+. to that sink. This mechanism was demonstrable anaerobically but did not prevent PQ+.-mediated O2- production under aerobic conditions.
Rabinowitch
H D
HD
Department of Field and Vegetable Crops, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel.
Rosen
G M
GM
Fridovich
I
I
D000693:Anaerobiosis; D002412:Cations / Q000378:metabolism; D000460:Chlorophyta / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000378:metabolism*; D005609:Free Radicals; D008027:Light; D010269:Paraquat / Q000378:metabolism*; D013045:Species Specificity
D002412:Cations; D005609:Free Radicals; D010269:Paraquat