Brachyury expression in the adult ctenophore, Pleurobrachia bachei.

Abstract

Brachyury is a transcription factor important for mesoderm formation in chordates. Ctenophores are basal metazoans with little known about their germ layer organization. For this reason, brachyury was used as a possible mesodermal marker in the ctenophore Pleurobrachia bachei . The gene was cloned and then used for in situ hybridizations in adults. This revealed distinctive expression patterns in the tentacles and combs of the animal, with banding patterns indicative of possible muscle cells. The Pb brachyury sequence was also used to help validate extant gene models. It was found that these models did not correctly predict the brachyury gene structure. For this reason, the gene models were updated with new training data. The results of this were still pending at the time this paper was completed (June 1, 2012). Further research also needs to be done on brachyury expression in Pleurobrachia bachei embryos to completely understand its role in ctenophore development.