Dimethylsulfoniopropionate, a cryoprotectant in marine ciliates?

Friday, February 12, 2016
Sophia AuDuong, Plymouth North High School, Plymouth, MA
Dimethylsulfoniopropionate (DMSP) is a tertiary sulfur-containing compound found in many Arctic and Antarctic marine phytoplankton and bacteria. Involved in both biological and environmental pathways, DMSP’s applications remain largely undiscovered. Although its primary function and purpose is not confirmed, DMSP has been speculated to play a role as a cryoprotectant. A cryoprotectant is a chemical that enables intracellular functions to continue in below freezing temperatures. In this experiment, the role of DMSP as a potential cryoprotectant in marine ciliates is investigated. The hypothesis was if polar marine ciliates Mesodinium rubrum (M.rubrum) and Geminigera cryophila (G. cryophila) were cultured in a 4°C environment, then the DMSP concentration of those would be higher than the temperate M.rubrum and G.cryophila ciliates cultured in an 18°C environment. Some of the data collected through experimentation supported the hypothesis but not all.  The polar ciliates M. rubrum samples did not exhibit levels of DMSP above the minimum concentration capable of being detected by the gas chromatograph (0.1 nM per 5 mL) thereby not allowing for a comparison of  DMSP levels with the temperate M. rubrum ciliates. However, the polar ciliates G. cryophila measured to have on average ten times more DMSP when compared to the G. cryophila temperate ciliates, supporting the initial hypothesis. To remedy the low DMSP levels in the polar M. rubrum, a larger concentration of ciliates should be tested. Further alterations to this experiment would include shock and assimilation trials and more precise testing of DMSP levels in the G. cryophila cultured at sub-zero temperatures.