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Yang-Tsung Lin (Benning lab)

Date & Location: October 13, 2020, at 12p; Virtual talk

Subject: Mis-regulation of the transcriptome in a Chlamydomonas mutant during cell division cycle and nitrogen-starvation induced quiescence

Abstract: Control of the cell cycle is directly linked to cell differentiation in multicellular organisms, but in unicellular organisms like microalgae, the progression through the appropriate stages of the cell cycle is critical for survival in a changing environment. Depending on the surrounding environmental factors such as light and nutrients, an algal cell needs to decide whether to undergo cell division or enter a resting (quiescent) state. In the model organism Chlamydomonas, most cell cycle studies have focused on the regulatory mechanism of the cell division cycle and metabolic remodeling during nutrient deprivation-induced quiescence. However, the link between the two states, especially how Chlamydomonas programs the expression of cell cycle genes to transition between cell division and quiescence, is largely unknown.

Recently, a regulator of quiescence transition in Chlamydomonas, Compromised Hydrolysis of TAG 7 (CHT7), was identified in the Benning lab. Subsequent work has shown that CHT7 is required for cells to survive during quiescence. To further investigate the cell cycle control mechanism of CHT7 in Chlamydomonas, we performed an RNA-Sequencing experiment to investigate the transcriptomic dynamics of synchronized cht7 cells at different stages of the cell cycle. The preliminary data indicate that cell cycle-related genes involved in DNA replication, DNA repair, and chromosome organization are derepressed in the cht7 mutant during both the cell division cycle and during quiescence, suggesting CHT7 is a negative regulator of these genes. FACS analysis also revealed that cht7 mutant generally have a higher DNA content than the control strains throughout the cell cycle. These results imply the possible role of CHT7 in modulating the S-phase of Chlamydomonas. A further characterization of these potential CHT7-targeted genes will provide more insight into the regulation of life cycle transitions in microalgae.

Speaker Lab: Dr. Christoph Benning