Project description:Past studies have shown that the photosynthetic apparatus of a psychrophilic alga C. sp. UWO241 is remodeled to support high rates of Photosystem I (PSI)-associated cyclic electron flow (CEF). Iron levels in ELB are in the nanomolar range; therefore, we hypothesized that PSI restructuring in C. sp. UWO241 may reflect a strategy to survive long-term Fe-deficiency. We studied the effect of Fe availability in C. sp. UWO241, a mesophile, C. reinhardtii, and a second ELB psychrophile, Chlamydomonas sp. ICE-MDV. Under Fe-deficient conditions (2 µM Fe), abundance of the PSI reaction center protein, PsaA, as well as levels of photooxidizable P700 (ΔA820/A820) were significantly reduced in both psychrophiles relative to C. reinhardtii. In response to increased Fe, C. sp. ICE-MDV exhibited increases in PSI 77K Chl a fluorescence and ΔA820/A820 which matched that of C. reinhardtii, while C. sp. UWO241 exhibited moderate restoration of PSI function. Our results indicate that PSI functional organization in C. sp. UWO241 is unique. The unique physiological traits in PSI photochemistry exhibited by the psychrophiles may reflect adaptation to the stratified physicochemical conditions present the shallow vs. deep photic zones of a chemically Antarctic lake.
Project description:We investigated the functional gene expression changes associated with temperature stress in two psychrophilic sea ice bacteria, Polaribacter sp. ALD9 and Shewanella sp. ALD11.
Project description:We combined a highly synchronous photobioreactor culture system with frequent temporal sampling to characterize genome-wide periodic gene expression in Chlamydomonas.
Project description:High throughput sequencing was used to investigate the production of small RNAs from in Chlamydomonas in different strains and different stages of the life cycle. The association between these and methylation was assessed using genomic sequencing, comparing a sequenced genome with one enriched for methylated DNA sequence by immuno-precipitation.
