Molecular characterization and evolution of X and Y-borne ATRX homologues in American marsupials.

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.

SOX9 has both conserved and novel roles in marsupial sexual differentiation.

In addition to an essential role in chondrogenesis, SOX9 is a highly conserved and integral part of the testis determining pathway in human and mouse. To determine whether SOX9 is involved in sex determination in noneutherian mammals we cloned a marsupial orthologue and studied its expression. The tammar wallaby SOX9 gene proved to be highly conserved, and maps to a region of the tammar genome syntenic to human chromosome 17.