Meeting Abstract

S2-1.7  Thursday, Jan. 3  Neural Crest Segments in Zebrafish SCHILLING, T.F.; Univ. of California, Irvine tschilli@uci.edu

In the vertebrate head, cranial neural crest (NC) cells migrate from specific segmental levels of the hindbrain to form skeletal elements of the pharyngeal arches, as well as segmentally organized neurons and glia of the peripheral nervous system. Our lab has been studying how hindbrain and pharyngeal segmentation are coordinated in embryos of the zebrafish, Danio rerio, by analyzing mutants in genes required for NC development and imaging living NC cells as they migrate. Most recently, we have been using transgenic zebrafish in which we have targeted a membrane-tethered version of GFP to NC cells with a sox10 promoter (sox10:egfp), to follow migrating NC cells with confocal time-lapse microscopy from their origins in the hindbrain into the arches. We demonstrate that although early pharyngeal arch formation is NC-independent, many of the segment-specific migration and proliferation patterns of NC cells are intrinsic to the NC cells themselves. One intrinsic determinant is the transcription factor, Tfap2a, mutations in which disrupt hoxa2 expression in NC cells and skeletal development in the second pharyngeal arch. Genome-wide screens for downstream targets of Tfap2a have identified several cytoskeletal regulators (e.g. unconventional myosins, actin-binding proteins), expressed specifically in NC cells, that control filopodial dynamics during migration. Experiments using sox10:egfp are now underway to determine requirements for these genes in NC morphogenesis, and in restricting NC movements within segmental compartments.