The propagation of nearly all animals requires the production of functional male and female gametes. Fertilization of the oocyte by male gametes (sperm) enables the developing egg to produce all of the cell types of the resulting organism. What mechanisms are used to generate functional gametes and to what extent are these mechanisms shared between different organisms? This is a major biological problem that involves development, differentiation, and, to some extent, de-differentiation. This work uses the tools of genomics and the unique biology of the planarian to understand the generation of male gametes (spermatogenesis). Planarians are well-known for their ability to regenerate a complete organism from almost any part of the body; it is less appreciated that they can also regenerate their reproductive organs, using an adult ?stem cell? population as the source of new tissue. The availability of the planarian genome sequence, techniques for studying the expression of tens of thousands of genes simultaneously, and the ability to manipulate gene function in this organism will facilitate the identification of genes required for proper spermatogenesis. This work will identify genes necessary for spermatogenesis that are shared between planarians and other organisms, including mammals. The broader educational impact of this work will be in the training of graduate and undergraduate students in the use of functional genomic approaches to study important problems. Furthermore, the P.I. and the members of his laboratory are actively engaged in outreach activities designed to increase the interest of K-12 students and members of under-represented groups in scientific research.
The successful propagation of sexually reproducing species requires the production of functional gametes: sperm from males and oocytes from females. Upon fertilization, sperm unleash the totipotency of the oocyte, activate the egg, and contribute paternal factors necessary for further development. How is this highly specialized cell type produced? What shared mechanisms are used to produce sperm in widely divergent organisms? What mechanisms generate the species-specific functions of these gametes? This work capitalized on the unique biological properties of the planarian Schmidtea mediterranea and the experimental accessibility of this organism to dissect the molecular mechanisms underlying spermatogenesis. Work enabled by this award identified genes expressed during specific stages of spermatogenesis and characterized the cell types in which these genes are expressed. We found several genes conserved between planarians and mammals that regulate proper progression through spermatogenesis; some of these factors act systemically to control the development and maintenance of the reproductive system. This research has provided an outstanding training opportunity for graduate students and undergraduates to learn functional genomic approaches to study important biological questions. Furthermore, this award has facilitated the engagement of the PI and members of his laboratory in outreach activities that increase the interest of K-12 students in scientific research.
