Takeuchi Masaki    Department   Kawasaki University of Medical Welfare  ,    Position   Associate Professor
Language	English
Title	Developmental Roles of siamois-related Gene in a Basal Actinopterygian: Functional and Evolutionary Implications
Conference	The 46th Annual Meeting for the Japanese Society of Developmental Biologists (cosponsor: the Asia-Pacific Developmental Biology Network)
Conference Type	Nationwide Conferences
Presentation Type	Speech
Lecture Type	General
Publisher and common publisher	◎Masaki Takeuchi, Shinichi Aizawa
Date	2013/05/29
Venue (city and name of the country)	Kunibiki Messe (Matsue, Japan)
Summary	In Xenopus, siamois is essential to the formation of the Spemann’s organizer and mediates dorsal Wnt signaling. No siamois-related genes have been found yet in other taxa, but we found it in our bichir EST database. We named the bichir gene “dioskouroi (dios)” after the twin gods that became the symbol for Gemini. As well as siamois, dios has a strong axis-inducing activity in Xenopus embryos and acts as the transcriptional activator for secondary axis induction. Importantly, dios can also rescue the headless phenotype of siamois/twin double-knockdown embryos. Therefore, we identified bichir dios and Xenopus siamois as homologs. To confirm endogenous roles of dios in bichir embryogenesis, we performed depletion of dios by morpholino antisense microinjection. As results, bichir embryos were prevented gastrulation and form no embryonic axis and structures by dios-knockdown. These dios-knockdown phenotype of bichir embryos is much more severe than the headless phenotype by siamois/twin-knockdown in Xenopus embryos. In addition, it is revealed by the marker analysis that the endoderm differentiation also inhibited by dios-knockdown. Thus dios plays roles not only in organizer formation but also in endoderm differentiation in bichir, distinct from siamois in Xenopus. Based on these data, we will discuss about the evolution of siamois-related genes and their usage for early embryogenesis.