Abstract
Arsenic is a toxic element that is widely distributed in the soil and fresh water environments. Although arsenate has been used for screening of photosynthetic mutants in Chlamydomonas reinhardtiiby Prof. Togasaki, it is still unclear why photosynthetic mutants exhibit arsenate-resistance. In this study, we observed that cells incubated in the dark are more resistant to arsenate than in light. In the dark, the inhibition of photosynthetic activity by arsenate and the arsenate uptake were both about a half of those in light. Furthermore, in the presence of both phosphate and arsenate (1mM each), inhibition of phosphate uptake by arsenate and that of arsenate uptake by phosphate in the dark were larger than in light. This is considered to be the cause of the lower inhibition rate of photosynthetic activity in the dark than in light, suggesting photosynthesis has a positive effect on arsenate uptake.
