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Surprisingly complex T‐box gene complement in diploblastic metazoans
Author(s) -
Yamada Atsuko,
Pang Kevin,
Martindale Mark Q.,
Tochinai Shin
Publication year - 2007
Publication title -
evolution and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 78
eISSN - 1525-142X
pISSN - 1520-541X
DOI - 10.1111/j.1525-142x.2007.00154.x
Subject(s) - biology , brachyury , bilateria , phylogenetic tree , sea anemone , gene , evolutionary biology , phylogenetics , cnidaria , most recent common ancestor , gastrulation , genome , genetics , mesoderm , embryogenesis , embryonic stem cell , ecology , coral
SUMMARY Ctenophores and cnidarians are two metazoan groups that evolved at least 600 Ma, predating the Cambrian explosion. Although both groups are commonly categorized as diploblastic animals without derivatives of the mesodermal germ layer, ctenophores possess definitive contractile “muscle” cells. T‐box family transcription factors are an evolutionarily ancient gene family, arising in the common ancestor of metazoans, and have been divided into eight groups in five distinct subfamilies, many of which are involved in the specification of mesodermal as well as ectodermally and endodermally derived structures. Here, we report the cloning and expression of five T‐box genes from a ctenophore, Mnemiopsis leidyi . Phylogenetic analyses demonstrated that ctenophores possess members of at least three of the five T‐box subfamilies, and expression studies suggested distinct roles of each T‐box genes during gastrulation and early organogenesis. Moreover, genome searches of the sea anemone, Nematostella vectensis (anthozoan cnidarian), showed at least 13 T‐box genes in Nematostella , which are divided into at least six distinct groups in the same three subfamilies found in ctenophores. Our results from two diploblastic animals indicate that the common ancestor of eumetazoans had a complex set of T‐box genes and that two distinct subfamilies might have appeared during triploblastic evolution.