Meeting Abstract

34.1  Friday, Jan. 4  Neural development in the polychaete annelid Capitella sp. I SEAVER, Elaine C.*; MEYER, Neva P.; University of Hawaii; University of Hawaii seaver@hawaii.edu

A key step during early central nervous system development is fate specification of neural precursor cells, which generate the entire brain and nerve cord. To date, the basic mechanisms of neural precursor cell fate specification are best understood in ecdysozoans and deuterstomes and are only now beginning to be explored in lophotrochozoans. In this study we provide an overview of brain development, including neural precursor cell characterization, in a lophotrochozoan annelid, Capitella sp. I. Using lineage tracing techniques, we determined that Capitella brain neural precursor cells originate locally from anterior ectoderm and do not appear to migrate long distances to form ventral nerve cord ganglia as is seen in some mollusks. However, in a manner similar to that seen in mollusks, chelicerates and myriapods, these precursor cells proliferate in the surface ectoderm prior to internalization. In addition, Capitella brain neural precursor cells are primarily internalized by ingression rather than by delamination or invagination. This is similar to chelicerates and myriapod neural precursor cells which ingress to form the central nervous system, although they ingress in groups rather than as single cells. We have also begun to characterize putative neurogenic genes and report how their expression patterns correlate with specific neurogenic events such as neural precursor cell internalization, exit from a proliferative region, and acquisition of a differentiated phenotype. Characterization of Capitella brain neural precursors allows for interesting evolutionary comparisons at the cellular level as well providing a basis for future efforts to understand the molecular mechanisms of neural precursor fate specification in a lophotrochozoan.