Determining the molecular basis of Holospora infection on closely related susceptible and resistant strains of Paramecia

Abstract

Paramecium caudatum is a single-celled pond-dwelling ciliate that can be infected by its endosymbiotic partner, bacterium Holospora undulata. Multiple strains of P. caudatum can have varying levels of susceptibility to infection by H. undulata, indicating there are factors that contribute to susceptibility such as environmental and genetic factors. Previous research in the Bright laboratory has determined 38 genes are highly upregulated in P. caudatum during H. undulata infection. Further investigation of these genes is presented in this study to determine their involvement in infection response. We performed various bioinformatic analyses, such as z-tests, to determine if any type of selection (i.e., positive, purifying, or neutral selection) is occurring on these genes. In this research paper, we want to determine the molecular basis for these changes in susceptibility to infection, and to detect any evolutionary constraints on genes involved in infection.