Chromosomal distribution of two multigene families and the unusual occurrence of an X1X1X2X2/X1X2Y sex chromosome system in the dolphinfish (Coryphaenidae): an evolutionary perspective.
Dolphinfishes (Coryphaenidae) are pelagic predators distributed throughout all tropical and subtropical oceans and are very important for commercial, traditional, and sport fishing. This small family contains the Coryphaena hippurus and Coryphaena equiselis species whose chromosomal aspects remain unknown, despite recent advances in cytogenetic data assimilation for Perciformes. In this study, both species were cytogenetically analyzed using different staining techniques (C-, Ag-, and CMA3 banding) and fluorescence in situ hybridization, to detect 18S rDNA and 5S rDNA. C. hippurus females exhibit 2n = 48 chromosomes, with 2m+4sm+42a (NF = 54). In C. equiselis, where both sexes could be analyzed, females displayed 2n = 48 chromosomes (2m+6sm+40a) and males exhibited 2n = 47 chromosomes (3m+6sm+38a) (NF = 56), indicating the presence of X1X1X2X2/X1X2Y multiple sex chromosomes. Sex-chromosome systems are rare in Perciformes, with this study demonstrating the first occurrence in a marine pelagic species. It remains unknown as to whether this system extends to other populations; however, these data are important with respect to evolutionary, phylogenetic, and speciation issues, as well as for elucidating the genesis of this unique sex system.
Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
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Soares
Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brasil.
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Bertollo
Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brasil.
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MB
Cioffi
Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
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GW
Costa
Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
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W
F Molina
D000818:Animals; D005075:Biological Evolution; D002874:Chromosome Mapping; D005260:Female; D005399:Fishes / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D005810:Multigene Family; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012730:Sex Chromosomes / Q000235:genetics*
D012337:RNA, Ribosomal, 18S