Meeting Abstract

47-2  Friday, Jan. 6 08:15 – 08:30  Cas9-mediated excision of brachyury in Nematostella vectensis disrupts development of the pharynx, organization of endoderm, and patterning of the oral-aboral axis SERVETNICK, M*; STEINWORTH , B; BABONIS, L; SIMMONS, D; SALINAS-SAAVEDRA, M; MARTINDALE , MQ; University of Washington Bothell ; Whitney Marine Lab, University of Florida ; Whitney Marine Lab, University of Florida ; Whitney Marine Lab, University of Florida ; Whitney Marine Lab, University of Florida ; Whitney Marine Lab, University of Florida mds56@uw.edu

The mesoderm was a key novelty in animal evolution, though we understand little of how mesoderm arose. brachyury, the founding member of the T-box gene family, is a key gene in chordate mesoderm development, though the gene was present in the opisthokont ancestor, long before mesoderm appeared. To examine the role of brachyury in a sister-group to triploblasts, we excised the gene using CRISPR/Cas9 in the diploblastic cnidarian Nematostella vectensis. In these embryos, the pharynx fails to form, endoderm organization is aberrant, ectodermal cell polarity is disrupted, embryos fail to elongate along the oral-aboral axis and patterning along this axis is perturbed. Analysis of gene expression by both qPCR and in situ hybridization shows that many genes both in the same expression domain, as well as outside the domain, of brachyury are affected, including downregulation of most Wnt genes at the oral pole. It is likely that some, though not all, effects of brachyury are mediated by its effect on Wnt gene expression.