Abstract
Diatoms may contribute about 25% the total primary production on the earth. Carbonic anhydrase(CA) is important factor for carbon assimilation. The regulation of expression of CA by CO2 and light and its intracellular location were studied with P. tricornutum. Both under light and dark, CA expression increased at both mRNA and protein accumulation level upon transferring cells from 5%CO2 to air. The expression level in the light was higher than that in the dark. By prolonged exposure to air for 5 days, the level of mRNA accumulation gradually increased and oscillated at an interval of about 24h. These results predicate that CA expression is triggered by changes in [CO2] in the medium and light helps mRNA accumulation. Also CA expression seems to relate with cell cycles. Chimeric protein which possesses 46 N-terminal sequence of Β-CA precursor joined with GFP was expressed in P. tricorutum and found to locate in chloroplast.
