Meeting Abstract

S3.2-3  Saturday, Jan. 4 11:30  Epithelium establishment and tentacle development in Nematostella vectensis GIBSON, Matt*; IKMI, Aissam; FRITZ, Ashleigh; RAGKOUSI, Katerina; Stowers Institute for Medical Research mg2@stowers.org

Evolution of the capacity to form secondary epithelial outgrowths from the principal embryonic axes was a crucial innovation that potentiated the diversification of animal body plans. Nevertheless, the mechanisms regulating embryonic appendage development remain largely unexplored in early-branching metazoans. Here, I will describe our efforts to approach this problem from both cellular and developmental perspectives using Nematostella tentacle morphogenesis as a model system. We find that three fundamental processes contribute to the initial stage of embryonic tentacle development. First, a pseudostratified ectodermal placode forms at the oral pole of developing larvae and is transcriptionally patterned into four tentacle buds. Subsequently, Notch signaling-dependent changes in apicobasal epithelial thickness drive elongation of these primordia. In parallel, oriented cell rearrangements revealed by clonal analysis correlate with shaping of the elongating tentacles. While these events outline the cellular basis for morphogenesis of the first quartet of tentacles, a determinate and surprisingly complex spatio-temporal pattern of tentacle addition unfolds during subsequent developmental stages. Combined, our results suggest that spatial control over relatively simple transformations of epithelial architecture could have played a central role in body plan evolution.