MEASURING PHOTOSYNTHETIC HEALTH IN CULTURES OF THE HAPTOPHYTE CHRYSOCHROMULINA PARVA

Simultaneous analysis of carbon assimilation and chlorophyll fluorescence provides insights into algal photosynthetic health and primary productivity. Chrysochromulina parva is a widely distributed freshwater haptophyte that can be infected with multiple viruses isolated from Lake Ontario. The goal of our research is to determine if viruses have an impact on C. parva’s photosynthetic performance and carbon fixation. Recently we isolated C. parva cells that recovered after infection with the virus CpV-BQ1. These virus-resistant cells continue to divide while also producing viruses raising questions about their physiological status and photosynthetic efficiency. Initially, a LI-COR® 6800 was used to generate light response curves (i.e., photosynthesis vs. irradiance) and measure the fluorescence parameters Fv/Fm and PhiPS2 for both resistant C. Parva and naïve C. parva that hadn’t been exposed to viruses. When normalized to cell abundance, and across irradiances ranging from 100 to 1000 micromole m^-2 s^-1, carbon assimilation was consistently ~1.5x higher for naïve C. parva cells compared to resistant cells. Further, PhiPS2 values, which indicate photosynthetic efficiency, were between 1.15-1.3x higher for naïve cells at irradiances ranging from 300 to 900 micromole m^-2 s^-1. Following this pilot experiment which revealed differences in photosynthetic performance between naïve and BQ1-resistant cells, additional growth experiments will be conducted to determine if this pattern is robust and directly demonstrate a virus’s influence on C. parva’s photosynthetic efficiency. 

Primary Presenter: Sophie Anderson, University of Toronto (sophie.anderson@mail.utoronto.ca)

Authors:

Sophie Anderson, University of Toronto  (sophie.anderson@mail.utoronto.ca)

Steven Short, University of Toronto  (steven.short@utoronto.ca)