title: A DNA fragment from the human X chromosome short arm which detects a partially homologous sequence on the Y chromosomes long arm.
abstract: An X linked human DNA fragment (named DXS31 ) which detects partially homologous sequences on the Y chromosome has been isolated. Regional localisation of the two sex linked sequences was determined using a panel of rodent-human somatic cell hybrids. The X specific sequence is located at the tip of the short arm ( Xp22 .3-pter), i.e. within or close to the region which pairs with the Y chromosome short arm at meiosis. However the Y specific sequence is located in the heterochromatic region of the long arm ( Yq11 -qter) and lies outside from the pairing region. DNAs from several XX male subjects were probed with DXS31 and in all cases a double dose of the X linked fragment was found, and the Y specific fragment was absent. DXS31 detects in chimpanzee a male-female differential pattern identical to that found in man. However results obtained in a more distantly related species, the brown lemur, suggest that the sequences detected by DXS31 in this species might be autosomally coded. The features observed with these X-Y related sequences do not fit with that expected from current hypotheses of homology between the pairing regions of the two sex chromosomes, nor with the pattern observed with other X-Y homologous sequences recently characterized. Our results suggest also that the rule of conservation of X linkage in mammals might not apply to sequences present on the tip of the X chromosome short arm, in bearing with the controversial issue of steroid sulfatase localisation in mouse.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics*; D012734:Disorders of Sex Development; D005260:Female; D006801:Humans; D006822:Hybrid Cells / Q000502:physiology; D007621:Karyotyping; D008297:Male; D051379:Mice; D009693:Nucleic Acid Hybridization; D011110:Polymorphism, Genetic; D012729:Sex Chromosome Aberrations; D014960:X Chromosome / Q000032:analysis*; D014998:Y Chromosome / Q000032:analysis*
chemical_list: D004247:DNA