DISSERTATION RESEARCH: The evolutionary recruitment of effector genes into a novel sensory system

University Of California-Davis, Davis CA

Investigators

Abstract

The fruit fly Drosophila prolongata exhibits a unique set of sensory organs on the front legs. This study examines the genomics of their cells to learn how a group of genes is recruited to form a new specialized cell type. Distinct types of tissues and cells are differentiated by which genes are expressed. Cells produce their varied functions by turning the genes necessary for these roles on, while keeping other genes off. Errors in the expression of genes is one cause of developmental disorders and other diseases, yet the mechanisms of expression control are still not well understood. Observing the patterns of the recruitment process will illustrate how a new cell type evolves, how gene expression is controlled in different types of cells and tissue, and why expression control breaks down. This research will expand the training of a graduate student, who also leads public outreach activities at his university and provides research experiences for high school students and undergraduates. To study the gene recruitment process, the evolutionary history of genes expressed in the novel sensory organs of Drosophila prolongata will be inferred. The mRNA from forelegs of this and several closely related species will be sequenced. The gene sequences present in the mRNA reflect which genes are expressed. These will be filtered based on similarity to sequences of known sensory genes; those present only in D. prolongata samples represent genes that have acquired new tissue specificity. These genes will be compared to related genes in other fly species, including the well-studied D. melanogaster, to determine what characteristics make genes more malleable to expression shifts. The evolutionary patterns reflect naturally occurring variation and suggest mechanisms of creating expression control, factors relevant to gene regulation in other organisms.