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
論文種別	原著
言語種別	英語
査読の有無	査読あり
表題	Germ layer patterning in bichir and lamprey; an insight into its evolution in vertebrates
掲載誌名	正式名：Developmental biology 略　 称：Dev Biol ISSNコード：00121606/1095564X
巻・号・頁	332(1),pp.90-102
著者・共著者	Masaki Takeuchi, Maiko Takahashi, Masataka Okabe, Shinichi Aizawa
担当区分	筆頭著者
発行年月	2009/08
概要	Amphibian holoblastic cleavage in which all blastomeres contribute to any one of the three primary germ layers has been widely thought to be a developmental pattern in the stem lineage of vertebrates, and meroblastic cleavage to have evolved independently in each vertebrate lineage. In extant primitive vertebrates, agnathan lamprey and basal bony !shes also undergo holoblastic cleavage, and their vegetal blastomeres have been generally thought to contribute to embryonic endoderm. However, the present marker analyses in basal ray-!nned !sh bichir and agnathan lamprey embryos indicated that their mesoderm and endoderm develop in the equatorial marginal zone, and their vegetal cell mass is extraembryonic nutritive yolk cells, having non-cell autonomous meso-endoderm inducing activity. Eomesodermin (eomes), but not VegT, orthologs are expressed maternally in these animals, suggesting that VegT is a maternal factor for endoderm differentiation only in amphibian. The study raises the viewpoint that the lamprey/bichir type holoblastic development would have been ancestral to extant vertebrates and retained in their stem lineage; amphibian-type holoblastic development would have been acquired secondarily, accompanied by the exploitation of new molecular machinery such as maternal VegT.
DOI	doi:10.1016/j.ydbio.2009.05.543
文献番号	19433081