Role of Pax Genes in Patterning of the Spiralian Embryo

University Of Texas At Austin, Austin TX

Investigators

Abstract

Animal embryos undergo a process of spatial patterning which insures appropriate organ development at correct body locations. Certain aspects of this process arose early in animal evolution and are widely conserved among living species. Other aspects evolved more recently in particular groups, and account for the diversity of animal body plans. Dr. Shankland's research will investigate the function of Pax genes in the Spiralia, which includes the segmented worms, flatworms, and molluscs. Preliminary evidence from spiralians suggests that the formation of different tissue types is dependent upon the synthesis of specific Pax proteins in particular cells of the early embryo. To test this idea, a combination of molecular and embryological techniques will be employed in embryos of an experimentally amenable spiralian, the leech Helobdella. Individual experiments will examine the function of Pax proteins in the formation and differentiation of (i) muscle tissue and (ii) the central nervous system. Potentially interacting genes will also be characterized, in particular the Meox homeodomain protein that is thought to play a role in spiralian muscle development. Data obtained from these studies will provide a foundation of knowledge for evolutionary comparisons with embryos of other species. One subfamily of Pax genes, Pax-Beta, is unique to spiralians, and evolution of the Pax-Beta genes could therefore have contributed to the unique developmental features of spiralian embryos. Dr. Shankland will employ Gene knockdown studies to test this idea. Successful completion of these studies will elucidate the degree to which embryonic pattern formation and Pax gene function is conserved among different kinds of animals, and may reveal how novel Pax genes have contributed to the evolution of unique animal morphologies. The broader impacts of this proposal will lie primarily in the training of both graduate and undergraduate students.