Date of Award
Doctor of Philosophy
Genetics, Development and Cell Biology
Martin H. Spalding
The green algae species Chlamydomonas reinhardtii can acclimate to varied environmental CO2 concentration through an inducible CO2 concentration mechanism (CCM). The chloroplast stroma protein gene LCIB mutant strains exhibits an "air dier" phenotype, which demonstrated the acclimations are different in these conditions. This project first used RNA-Seq to query the Chlamydomonas reinhardtii transcriptome for regulation by CO2 and by the transcription regulator CIA5 (CCM1). Massive impacts of CIA5 and CO2 on the transcriptome were observed, and genes with distinctive expression patterns presented a rich source of candidates for new CCM components.
Two second-site mutant suppressor strains of the "air dier" phenotype suppressor were studied by the high through-put genome sequencing method, and a candidate list of possible locations of the suppressor mutations in these 2 strains were generated. The transcript levels of 5 major CCM genes LCIA, LCIB, LCI1, CAH1, and HLA3 were also portrait in 12 hour time courses and a variety of limiting CO2 conditions by quantitative real time PCR. In addition to the CCM, the effect of the nitrogen starvation (N-starvation) stress and the key starch biosynthesis enzyme ADP-glucose pyrophosphorylase mutation were described for photoautotrophic grown cells. General down regulations of photosynthetic genes and up-regulations of the nitrogen assimilation genes were similar to the other previous mixotrophic studies; on the other hand, several de novo fatty acid synthesis genes were negatively regulated, and many dark reaction genes maintained their expression levels better in contrast to the general down regulations triggered by the N-starvation for the mixotrophic cultures. Also, the up-regulations of many glyoxylate cycle genes in the starchless mutant were very similar between photoautotrophic and mixotrophic cultures, even without external acetate source.
Fang, Wei, "The CO2 concentrating mechanism and nitrogen starvation effects under photoautotrophic culture conditions of Chlamydomonas reinhardtii studied by high throughput DNA sequencing technology" (2015). Graduate Theses and Dissertations. Paper 14314.