Abstract
The green alga Chlamydomonas reinhardtii has over ten phosphate transporters including PTA types and PTB types.
C. reinhardtii strain AR3 is a mutant that is defective in one of the phosphate transporter genes, PTB1, and exhibits resistance to arsenate. A photosynthetic mutant CC981 also shows arsenate-resistance. It was showed that both mutants took up more phosphate but less arsenate than the wild type strain CC125 in the presence of equivalent concentrations of phosphate and arsenate.
We investigated the expression of phosphate transporter genes in these mutants and the wild type CC125 in the presence of various concentration of phosphate and arsenate. When 1mM arsenate was added in the presence of the same concentration of phosphate, transcription of PTA1 and PTA2 decreased in the wild type and expression of PTB2 increased in AR3. These results suggest that there are some genes whose expression is inhibited or promoted by the presence of arsenate.
