Jon P. Boyle
University of Pittsburgh

Title: “Moving up and down the ladder: does locus expansion and diversification define species-specific phenotypes in the Apicomplexa? Toxoplasma gondii as a working example.”

Abstract: The phylum Apicomplexa is composed of parasites that have an enormous impact on human and animal health. This includes the causative agents of malaria, cryptosporidiosis, and toxoplasmosis. In my lab we use the human parasite Toxoplasma gondii to understand the evolution of virulence and host range in eukaryotic pathogens. While most parasites have highly restricted and specialized life cycles involving only a limited number of host species, Toxoplasma gondii boasts an intermediate host range that includes both birds and all mammals studied to date. In order to understand the genetic basis for these distinct phenotypes, we are using comparative genomics to identify loci that distinguish T. gondii from its nearest relatives. While gene content across our query species is remarkably well conserved overall, we have found that tandemly expanded loci are by far the most distinguishing genomic feature. We are now investigating the role of select Toxoplasma-specific expanded loci in parasite biology, and have determined that one of these loci is responsible for a species-specific cellular phenotype in T. gondii, specifically the manipulation of host mitochondria. We are now using genetic tools to determine how this phenotype uniquely evolved in Toxoplasma gondii.