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Hox expression in the direct‐type developing sand dollar Peronella japonica
Author(s) -
Tsuchimoto Jun,
Yamaguchi Masaaki
Publication year - 2014
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/dvdy.24135
Subject(s) - hox gene , biology , strongylocentrotus purpuratus , sea urchin , coelom , body plan , deuterostome , bilateria , annelid , echinoderm , evolutionary biology , mesoderm , homeobox , genetics , anatomy , gene , vertebrate , microbiology and biotechnology , gene expression , phylogenetics , ecology , embryonic stem cell
Background: Echinoderms are a curious group of deuterostomes that forms a clade with hemichordates but has a pentameral body plan. Hox complex plays a pivotal role in axial patterning in bilaterians and often occurs in a cluster on the chromosome. In contrast to hemichordates with an organized Hox cluster, the sea urchin Strongylocentrotus purpuratus has a Hox cluster with an atypical organization. However, the current data on hox expression in sea urchin rudiments are fragmentary. Results: We report a comprehensive examination of hox expression in a sand dollar echinoid. Nine hox genes are expressed in the adult rudiment, which are classified into two groups, but hox11/13b belongs to both: one with linear expression in the coelomic mesoderm and another with radial expression around the adult mouth. The linear genes may endow the coelom/mesentery with axial information to direct postmetamorphic transformation of the digestive tract, whereas the radial genes developmentally correlate with the morphological novelties of echinoderms and/or sea urchins. Recruitment of the radial genes except hox11/13b appears to be accompanied by the loss of ancestral/axial roles. Conclusions: This in toto co‐option of the hox genes provides insight into the molecular mechanisms underlying the evolution of echinoderms from a bilateral ancestor. Developmental Dynamics 243:1020–1029, 2014 . © 2014 Wiley Periodicals, Inc.