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Expression of the cCdx‐B homeobox gene in chick embryo suggests its participation in rostrocaudal axial patterning
Author(s) -
Morales Aixa V.,
de la Rosa Enrique J.,
de Pablo Flora
Publication year - 1996
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/(sici)1097-0177(199608)206:4<343::aid-aja1>3.0.co;2-i
Subject(s) - biology , homeobox , homeobox a1 , embryo , dlx5 , microbiology and biotechnology , gene , cdx2 , genetics , emx2 , hnf1b , gene expression
cCdx‐B (formerly cHox‐cad 2 ) is a chick homeobox‐containing gene related to the Drosophila caudal. Compared with other caudal homologues, its similarity is highest with the murine Cdx‐4. In the present study, we characterize the localization of cCdx‐B transcripts to the caudal region of the embryo by using reverse transcription‐polymerase chain reaction (RT‐PCR) and, in detail, by using in situ hybridization. Chick embryos from gastrulation to early organogenesis were hybridized with digoxigenin‐labeled riboprobes, and the pattern of expression of cCdx‐B mRNA was analyzed in wholemount embryos and in tissue sections. In the early gastrula, transcripts were localized in a gradient through the caudal half of the embryo, in the epiblast and the mesoderm cells, but not including Hensen's node. During neurulation, cCdx‐B transcripts were found more rostrally, with high levels localized in Hensen's node and the posterior neural plate. Expression was also high in paraxial mesoderm, with a rostral limit in the most recently formed somite. There was no expression in definitive endoderm. During late neurulation and tail bud formation, cCdx‐B mRNA expression regressed posteriorly and was finally confined to the tail bud region. This pattern of expression of cCdx‐B, regulated in time and space, is different from that of the other known chick caudal homologue, cCdx‐A. Both genes may play a coordinated role in the posterior axial patterning of the chick embryo, whereas cCdx‐B may specify further the identity of the tail region. © 1996 Wiley‐Liss, Inc.