Sex chromosome evolution: platypus gene mapping suggests that part of the human X chromosome was originally autosomal.
To investigate the evolution of the mammalian sex chromosomes, we have compared the gene content of the X chromosomes in the mammalian groups most distantly related to man (marsupials and monotremes). Previous work established that genes on the long arm of the human X chromosome are conserved on the X chromosomes in all mammals, revealing that this region was part of an ancient mammalian X chromosome. However, we now report that several genes located on the short arm of the human X chromosome are absent from the platypus X chromosome, as well as from the marsupial X chromosome. Because monotremes and marsupials diverged independently from eutherian mammals, this finding implies that the whole human X short arm region is a relatively recent addition to the X chromosome in eutherian mammals.
Watson
J M
JM
Department of Genetics and Human Variation, La Trobe University, Bundoora, Victoria, Australia.
Spencer
J A
JA
Riggs
A D
AD
Graves
J A
JA
D000818:Animals; D005075:Biological Evolution; D015139:Blotting, Southern; D002460:Cell Line; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D015342:DNA Probes; D015186:Hominidae / Q000235:genetics*; D006801:Humans; D008322:Mammals / Q000235:genetics; D010987:Platypus / Q000235:genetics*; D014960:X Chromosome
D015342:DNA Probes; D004247:DNA