Isolation of cDNA clones of genes induced upon transfer of Chlamydomonas reinhardtii cells to low CO2.

Unicellular algae grow well under limiting CO2 conditions, aided by a carbon concentrating mechanism (CCM). In C. reinhardtii, this mechanism is inducible and is present only in cells grown under low CO2 conditions. We constructed a cDNA library from cells adapting to low CO2, and screened the library for cDNAs specific to low CO2-adapting cells. Six classes of low CO2-inducible clones were identified. One class of clone, reported here, represents a novel gene associated with adaptation of cells to air. A second class of clones corresponds to the air-inducible periplasmic carbonic anhydrase I (CAH1). These clones represent genes that respond to the level of CO2 in the environment.