Takeuchi Masaki    Department   Kawasaki University of Medical Welfare  ,    Position   Associate Professor
Article types	原著
Language	English
Peer review	Non peer reviewed
Title	The Genus Polypterus (Bichirs): A Fish Group Diverged at the Stem of Ray-Finned Fishes (Actinopterygii)
Journal	Formal name：Cold Spring Harbor Protocols ISSN code：19403402/15596095
Volume, Issue, Page	2009(5)
Author and coauthor	Takeuchi M, Okabe M, Aizawa S
Publication date	2009/05
Summary	Axis and germ-layer formations are central issues in vertebrate embryology that can be examined in the zebrafish, Xenopus, chick, and mouse. An intriguing question is how the mechanisms that existed in an ancestral vertebrate have been modified during vertebrate evolution. A major stream of vertebrates (Osteichthyes) evolved in two monophyletic lineages: the Sarcopterygii and Actinopterygii. The zebrafish is a well-known and well-studied teleost fish highly derived in the actinopterygian lineage, ray-finned fishes. The early cleavage pattern of teleosts is meroblastic, in contrast to the holoblastic cleavage seen in amphibians, which diverged early in the sarcopterygian lineage. There are many differences in the molecular and cellular mechanisms of embryogenesis between teleosts and amphibians or actinopterygians and sarcopterygians, including the differences in bauplan (body plan). However, the lineage leading to the teleost fishes has undergone a whole-genome duplication before their radiation, which may have also caused changes in molecular usage independent of the teleost bauplan. Polypterus diverged from all other actinopterygians ~400 million years ago (Mya) during the Devonian period, soon after the divarication of an ancestral bony fish into Actinopterygii and Sarcopterygii. Polypterus is thus uniquely well suited for studies assessing the ancestral state or bauplan of Osteichthyes and Actinopterygii, as well as the divergence of embryogenetic processes in teleosts and amphibians.
DOI	doi:10.1101/pdb.emo117
Document No.	PMID: 20147149