Chlamydomonas CHT7 Represses DNA Replication and Mitotic Genes Counteracting CDK-Stimulated Cell Division

The transcriptome of a Chlamydomonas mutant, cht7, was compared with those of the two control strains. The CHT7 protein has been shown to play a role in regulating the transition into and out of a nitrogen-induced cell-cycle resting state, quiescence. To further clarify the role of CHT7 in cell cyle regulation, we performed RNA-seq to investigate the transcriptomic dynamics of photoautotrophically grown, synchronized cells of cht7 and the two controls at different stages of the cell cycle. The three strains, 6145c/Wild type (Control 1), CHT7-HA::cht7 (Control 2), and cht7, were grown photoautotrophically (12h: 12h Light: Dark) to synchronize them. Samples for RNA-seq were harvested at different timepoints representing different stages of the cell cycle. There are three major sets of samples: ZT samples represent cells undergoing a normal cell division cycle (ZT0: G0, ZT6: G1, ZT10 and 12: S/M). ND samples represent cells in the quiescence state. NR samples represent cells after resupply of nitrogen, resuming the cell division cycle.