CAREER: Functional Genomic Analysis of Germ Cell Development and Regeneration in Planarians

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

0237825 Newmark The specification of primordial germ cells is the first step required for the successful propagation of sexually reproducing species. In spite of the biomedical and evolutionary implications of understanding how the germline is formed and how totipotency is established and maintained in germ cells, we are far from understanding these processes in detail. In the best-studied invertebrates and many vertebrates, germ cells are specified by maternally supplied, cytoplasmic determinants. In mammals, however, germ cell specification proceeds epigenetically, requiring inductive interactions. The mechanisms linking these different modes of specification remain unclear. The research outlined here will investigate the epigenetic specification of germ cells using planarians- classic subjects of regeneration studies- as a model. Planarians can regenerate complete organisms from tiny body fragments; their germ cell lineage displays similar plasticity. Planarian germ cells form from adult stem cells only when the flatworm attains the appropriate size. This research will utilize genetic differences between wild-type sexual planarians and an asexual strain that lacks all reproductive structures and reproduces by transverse fission. Expressed sequence tags will be generated from the sexual planarians, and microarray analyses will identify genes expressed preferentially during sexual reproduction. The cell types in which these genes are expressed will be defined by automated in situ hybridization. Functional assays using double-stranded RNA will be used to identify genes required for germ cell specification and differentiation. These experiments will provide insight into the mechanisms by which germ cells are specified via inductive interactions and the extent to which these mechanisms have been conserved evolutionarily. The educational component of this proposal includes science outreach to local elementary school students. Planarians will be used in demonstrations that will reinforce many of the key biological concepts that elementary school students are expected to master. The demonstrations should also provide students with a sense of the curiosity and wonder that drive scientific research. A new graduate core course in cell biology will be developed; this course will be taught from an experimental perspective, highlighting readings from the primary literature and emphasizing critical thinking skills. Finally, to increase the scientific literacy of students from the humanities and social sciences, a new course will be developed, using news media coverage of biotechnology as a framework for teaching basic concepts of biology.