Derek Ou, 2015, Mathematics

Diatoms are responsible for 20% of carbon fixation via photosynthesis globally,and are therefore an important contributor to the carbon cycle. However, their physiology, unlike that of plants, is not well understood. This summer, I worked at the Morel Laboratory to investigate diel cycles in carbon fixation and Ribulose 1,5 bisphosphate carboxylase oxygenase (Rubisco) abundance in the marine diatom Thalassiosira weissflogii (Tw). Rubisco is the enzyme that catalyzes CO2 fixation in the first step of the Calvin Cycle and is widely recognized as the rate limiting step for photosynthesis, making it attractive for study when investigating carbon fixation. I cultured Tw in sterile seawater amended with Aquil nutrients, trace metals, and vitamins, acclimated my cultures to a 12:12 day:night cycle, harvested the cells, and measured short-term rates of carbon fixation and protein abundance using radioactive C-14 and Western Blotting, respectively. I also used flow cytometry to investigate patterns in the rate of cell division and measured photosynthetic efficiency using a Fluorescence Induction and Relaxation system. During my experiments, I observed clear diel patterns in carbon fixation, protein abundance, Rubisco abundance, cell division, and photosynthetic efficiency. As a mathematics student who hopes to conduct more research in the biosciences in the future, I was able to gain valuable research experience from this internship, and matured as a scientist.