Meeting Abstract

16.6  Monday, Jan. 4  Ascidian neural tube morphogenesis proceeds normally following ablation of the notochord DANAHER, B.*; MUNRO, E.; SHERRARD, K.; ROBIN, F.; University of Washington; University of Washington; University of Washington; University of Washington brooke.danaher@gmail.com

Ascidian neurulation proceeds through concurrent invagination and extension of a monolayer neural plate. The underlying notochord forms simultaneously through invagination and convergent extension of a monolayer plate into a cylindrical rod. The notochord is a likely candidate for effecting neural morphogenesis: it is the substrate for neural tissue throughout neurulation, and its robust convergent extension is a probable source of extensile force in the ascidian tailbud. Here we use laser ablation at the 64-cell stage and time lapse confocal microscopy to examine neural morphogenesis in the absence of a notochord. We show that neural plate organization, invagination, and neural tube closure all continue normally. Neural tube extension is slightly limited, but neural cells retain normal organization and significant elongation. Our results indicate that neural morphogenesis is a robust process, and suggest alternative driving forces for ascidian tailbud elongation.