タケウチ　マサキ   Takeuchi Masaki   竹内　雅貴    所属   川崎医療福祉大学  医療技術学部 臨床検査学科    職種   准教授
言語種別	英語
発表タイトル	The early embryogenesis of Polypterus (bichirs): Insights into the origin and evolution of vertebrate body plans
会議名	20th CDB Meeting: Molecular Bases for Evolution of Complex Traits
学会区分	国際学会及び海外の学会
発表形式	ポスター掲示
講演区分	一般
発表者・共同発表者	◎Masaki Takeuchi, Maiko Takahashi, Shinichi Aizawa
発表年月日	2011/02/23
開催地 （都市, 国名）	Kobe, Japan
概要	Germ layer patterning and body axis formation are central issues in vertebrate embryology. An intriguing question is how the mechanisms that existed in an ancestral vertebrate have been modified during vertebrate evolution. Here I would like to discuss about insights from bichir (most basal ray-finned fish) embryogenesis into these evolution in vertebrates. Importantly, bichir embryogenesis is similar to amphibian rather than teleost, in many aspects such as holoblastic cleavage. All blastomeres in amphibian develop into the primary germ layers. However, not only in bichir but also in agnathan lamprey, meso-endoderm develop in the marginal zone, and vegetal cell mass is extraembryonic yolk cells. This suggests that the lamprey/bichir holoblastic development is ancestral to extant vertebrates, that their pattern was responsible for the frequent transitions from holoblastic to meroblastic cleavage as a pre-pattern in the vertebrate lineage, and that amphibian holoblastic development was acquired secondarily accompanied by the exploitation of lineage-specific molecular machineries such as maternal VegT. An additional topic is about the existence and significance of a bichir homolog of Xsiamois, which is the head inducible gene previously found only in amphibian. It is suggested that siamois-related protogene was required for the axis formation in the common ancestor of Osteichthyes.