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Chromosomal mapping of ANTP class homeobox genes in amphioxus: piecing together ancestral genomes
Author(s) -
Castro L. F. C.,
Holland P. W. H.
Publication year - 2003
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 - 10.1046/j.1525-142x.2003.03052.x
Subject(s) - homeobox , hox gene , homeobox a1 , biology , homeobox protein nkx 2.5 , hnf1b , genetics , genome , gene , gene cluster , dlx5 , gene duplication , emx2 , chromosome , evolutionary biology , transcription factor
Summary Homeobox genes encode DNA‐binding proteins, many of which are implicated in the control of embryonic development. Evolutionarily, most homeobox genes fall into two related clades: the ANTP and the PRD classes. Some genes in ANTP class, notably Hox , ParaHox , and NK genes, have an intriguing arrangement into physical clusters. To investigate the evolutionary history of these gene clusters, we examined homeobox gene chromosomal locations in the cephalochordate amphioxus, Branchiostoma floridae . We deduce that 22 amphioxus ANTP class homeobox genes localize in just three chromosomes. One contains the Hox cluster plus AmphiEn , AmphiMnx , and AmphiDll . The ParaHox cluster resides in another chromosome, whereas a third chromosome contains the NK type homeobox genes, including AmphiMsx and AmphiTlx . By comparative analysis we infer that clustering of ANTP class homeobox genes evolved just once, during a series of extensive cis ‐duplication events of genes early in animal evolution. A trans ‐duplication event occurred later to yield the Hox and ParaHox gene clusters on different chromosomes. The results obtained have implications for understanding the origin of homeobox gene clustering, the diversification of the ANTP class of homeobox genes, and the evolution of animal genomes.