Meeting Abstract

66.9  Friday, Jan. 6  Molgulid ascidians show an early heterochronic shift in the expression of genes critical for metamorphosis in other ascidians MALISKA, M.E.*; PIERCE, T.; HAUSCH, P.; BROWN, C.T.; SWALLA, B.J.; Department of Biology, University of Washington; Department of Biology, University of Washington; Department of Biology, Ripon College; Department of Computer Science and Engineering and the Department of Microbiology and Molecular Genetics, Michigan State University; Department of Biology, University of Washington mem24@uw.edu

Ascidian species (Tunicata: Ascidiacea) in the Molgulidae are found to have urodele, tailed, chordate larvae with notochord and muscle as well as closely related species with anural, tailless larvae that completely lack larval structures, including the sensory otolith and muscle and notochord in the tail. This loss of a tailed larva is likely to have happened at least four times evolutionarily and is tractable at the molecular level. To examine how this development has affected the expression of genes critical for tail and notochord resorption and metamorphosis in developing embryos, the transcriptomes of closely related tailed and tailless species, Molgula oculata and M. occulta, were sequenced throughout embryogenesis and counts were accumulated using an RNASEQ approach. Preliminary findings show that gene expression of several genes critical for metamorphosis, are heterochronically shifted in expression for both the tailed and tailless species when compared to other non-molgulid ascidian species. These results suggest that it will be critical to understand the similarities and differences of metamorphosis in the molgulid ascidians before further studies can be addressed into the evolution of taillessness.