Meeting Abstract

S9.1  Wednesday, Jan. 6  The complete cell lineage of the polychaete annelid Capitella teleta MEYER, N. P.; BOYLE, M. J.; MARTINDALE, M. Q.; SEAVER, E. C.*; University of Hawaii; University of Hawaii; University of Hawaii; University of Hawaii seaver@hawaii.edu

The polychaete annelid Capitella teleta (formerly Capitella sp. I) exhibits a spiral cleavage program, and has been the recent focus of several developmental studies aided by a fully sequenced genome. The life history of C. teleta includes formation of a lecithotrophic, metatrochophore larva with a simple metamorphic transition to the juvenile worm. Fate mapping in polychaetes has lagged behind maps generated for other spiralian taxa due to technical limitations. Using diI and confocal microscopy, we injected individual blastomeres through the formation of the fourth quartet of micromeres. Subsequent development was followed to characterize ultimate blastomere fates with single cell resolution during larval stages. Our results corroborate previous observations from classical studies and show a number of similarities with fate maps of other spiralians including: unique and stereotypic fates for individual blastomeres, presence of four discrete body domains arising from the A, B, C and D cell quadrants, and both ecto- and endo- origins of mesoderm. However, several features of C. teleta development show modifications of the typical spiralian fate map. For example, although 2d generates trunk and pygidial ectoderm, our analysis of the 2d sublineage reveals separate origins of the larval neurotroch and telotroch versus the definitive adult trunk ectoderm. In addition, we have identified at least five distinct cellular origins of mesoderm in C. teleta, including cells of the second quartet. The significance of these observations will be discussed by comparison with other annelid and spiralian fate maps.