title: Molecular characterization and evolution of X and Y-borne ATRX homologues in American marsupials.
abstract: In eutherians, the sex-reversing ATRX gene on the X has no homologue on the Y chromosome. However, testis-specific and ubiquitously expressed X-borne genes have been identified in Australian marsupials. We studied nucleotide sequence and chromosomal location of ATRX homologues in two American marsupials, the opossums Didelphis virginiana and Monodelphis domestica. A PCR fragment of M. domestica ATRX was used to probe Southern blots and to screen male genomic libraries. Southern analysis demonstrated ATRX homologues on both X and Y in D. virginiana, and two clones were isolated which hybridized to a single position on the Y chromosome in male-derived cells but to multiple sites of the X in female cells. In M. domestica, there was a single clone that mapped to the X but not to the Y, suggesting that it represents the M. domestica ATRX. However a male-specific band was detected in Southern blots probed with the D. virginiana ATRY and with a mouse ATRX clone, which implies that the Y copy in M. domestica has diverged further from other ATRX homologues. Thus there appears to be a Y-borne copy of ATRY in American, as well as Australian marsupials, although it has diverged in sequence, as have other Y genes that are testis-specific in both eutherian and marsupial lineages.
authors.affiliation: Research School of Biological Science, Australian National University, ACT 0200, Canberra, Australia. ds8@sanger.ac.uk
authors.forename: Denise R
authors.initials: DR
authors.lastname: Carvalho-Silva
authors.forename: Rachel J W
authors.initials: RJ
authors.lastname: O'Neill
authors.forename: Judith D
authors.initials: JD
authors.lastname: Brown
authors.forename: Kim
authors.initials: K
authors.lastname: Huynh
authors.forename: Paul D
authors.initials: PD
authors.lastname: Waters
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pask
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Delbridge
authors.forename: Jennifer A Marshall
authors.initials: JA
authors.lastname: Graves
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D004265:DNA Helicases / Q000235:genetics; D048293:Didelphis / Q000235:genetics*; D005260:Female; D015698:Genomic Library; D008297:Male; D008969:Molecular Sequence Data; D048309:Monodelphis / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D014960:X Chromosome / Q000235:genetics*; D000075924:X-linked Nuclear Protein; D014998:Y Chromosome / Q000235:genetics*
chemical_list: D009687:Nuclear Proteins; D004265:DNA Helicases; C092332:ATRX protein, human; D000075924:X-linked Nuclear Protein