title: H-Y antigen and the evolution of heterogamety.
abstract: In natural populations of platyfish, Xiphophorus maculatus, there are three sex chromosomes--W, X, and Y. Females may have one of three genotypes: WY, WX, or XX, and males may have either XY or YY. The W chromosome can be considered a modified X that blocks the male-determining function of the Y. The platyfish may represent an evolutionary stage at which female heterogamety arises through a single mutation, in the midst of a male heterogametic system. Our serological analysis revealed presence of H-Y antigen in XY and YY males, but not in XX, WX, or WY females, indicating that H-Y antigen may not be associated invariably with the heterogametic-type gonad--especially in transitional systems.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005260:Female; D005399:Fishes / Q000235:genetics* / Q000276:immunology; D006182:H-Y Antigen / Q000235:genetics*; D008297:Male; D012732:Sex Determination Analysis
chemical_list: D006182:H-Y Antigen