Unicellular algae acquire the ability to raise their internal CO2 concentrations under low-CO2 conditions because of the presence of a CO2 concentrating mechanism (CCM). In Chlamydomonas reinhardtii, this mechanism is induced when cells grown in high-CO2 conditions are switched to low-CO2 conditions. To elucidate the genes and proteins involved in this mechanism, we constructed a cDNA library from low CO2 adapted cells and differentially screened the library for cDNAs upregulated under low-CO2 conditions. Earlier studies identified six classes of clones specific to low CO2 adapting cells. To identify other genes and proteins playing a role in this mechanism, we have systematically characterized the cDNA clones that appear to be upregulated by low-CO2 adaptation but do not cross-hybridize with the six previously identified classes. We identified seven new classes of clones that are distinctly upregulated in low-CO2 conditions. These clones were checked by Northern analyses, sequencing, and homology studies. One class of clone represents a novel gene, lci 3. We report on the seven classes of clones and the characterization of lci 3.Key words: Chlamydomonas, CO2 concentrating mechanism, gene regulation, inducible genes, gene expression.
Changes in lipid and carotenoid metabolism in Chlamydomonas reinhardtii during induction of CO2-concentrating mechanism: Cellular response to low CO2 stress
