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Neural crest and evolution of the vertebrate body plan
Author(s) -
Kuratani Shigeru
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a88-c
Subject(s) - lamprey , neural crest , biology , vertebrate , hagfish , hox gene , anatomy , evolutionary biology , body plan , neuroscience , genetics , embryo , gene , paleontology , transcription factor
The neural crest is regarded as a defining character of vertebrates, and understanding of its evolution is a prerequisite for understanding the origin of vertebrates. The lamprey is a sister group of gnathostomes, and has served as a model for comparative embryology. By observing morphological distribution and gene expression patterns of the lamprey neural crest cells, it has become clear that the neural crest already had distinct spatial properties in the head and trunk of the embryonic body in the vertebrate common ancestor, as seen in the shared Hox code. As another shared genetic program, the molecules involved in epithelial‐mesenchymal interactions for the craniofacial patterning of the vertebrate ectomesenchyme are also homologous between gnathostomes and the lamprey. Especially, the aquisition of the jaw in gnathostomes appears to have been based primarily on the heterotopic shift of the shared tissue interaction, involving FGF/BMP signaling, not necessarily by an addition of a novel developmental program specific to gnathostomes. This signaling, however, does not result, in the lamprey, in the so called Dlx code, the gnathostome synapomorphy, although the lamprey has the same number of Dlx cognates as in non‐teleost gnathosotmes. This may explain a dorsoventrally symmetrical branchial arch morphology of the lamprey. The neural crest development in the hagfish embryo will also be discussed.