Evidence for Inorganic Carbon Transport by Intact Chloroplasts of Chlamydomonas reinhardtii

Abstract
Isolated intact chloroplasts from wall-less mutants of Chlamydomonas reinhardtii accumulate inorganic carbon (Ci) from the medium provided the cells had been adapted to low CO2 photoautotrophic growth conditions. Chloroplasts from cultures grown on high (5%) CO2 or photoheterotrophically with acetate did not accumlathe inorganic carbon. Chloroplast Ci accumulation from low CO2 grown cells was light dependent and was inhibited by uncouplers and inhibitors of electron transport. In a model for Ci accumulation by Chlamydomonas, it is proposed that CO2 diffuses into the cell and Ci accumulation occurs in the chloroplast.