ISOLATION OF CDNA CLONES OF GENES INDUCED UPON TRANSFER OF CHLAMYDOMONAS-REINHARDTII CELLS TO LOW CO2

Unicellular algae grow well under limiting CO, conditions, aided by a carbon concentrating mechanism (CCM). In C. reinhardtii, this mechanis m as inducible and is present only in cells grown under low CO2 condit ions. We constructed a cDNA library from cells adapting to low CO2, an d screened the library for cDNAs specific to low CO2-adapting cells. S ix classes of low CO2-inducible clones were identified. One class of c lone, reported here, represents a novel gene associated with adaptatio n of cells to air. A second class of clones corresponds to the air-ind ucible periplasmic carbonic anhydrase I (CAH1). These clones represent genes that respond to the level of CO2 in the environment.