title: Characterisation of ATRX, DMRT1, DMRT7 and WT1 in the platypus (Ornithorhynchus anatinus).
abstract: One of the most puzzling aspects of monotreme reproductive biology is how they determine sex in the absence of the SRY gene that triggers testis development in most other mammals. Although monotremes share a XX female/XY male sex chromosome system with other mammals, their sex chromosomes show homology to the chicken Z chromosome, including the DMRT1 gene, which is a dosage-dependent sex determination gene in birds. In addition, monotremes feature an extraordinary multiple sex chromosome system. However, no sex determination gene has been identified as yet on any of the five X or five Y chromosomes and there is very little knowledge about the conservation and function of other known genes in the monotreme sex determination and differentiation pathway. We have analysed the expression pattern of four evolutionarily conserved genes that are important at different stages of sexual development in therian mammals. DMRT1 is a conserved sex-determination gene that is upregulated in the male developing gonad in vertebrates, while DMRT7 is a mammal-specific spermatogenesis gene. ATRX, a chromatin remodelling protein, lies on the therian X but there is a testis-expressed Y-copy in marsupials. However, in monotremes, the ATRX orthologue is autosomal. WT1 is an evolutionarily conserved gene essential for early gonadal formation in both sexes and later in testis development. We show that these four genes in the adult platypus have the same expression pattern as in other mammals, suggesting that they have a conserved role in sexual development independent of genomic location.
authors.affiliation: Discipline of Genetics, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.
authors.forename: Enkhjargal
authors.initials: E
authors.lastname: Tsend-Ayush
authors.forename: Shu Ly
authors.initials: SL
authors.lastname: Lim
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pask
authors.forename: Diana Demiyah Mohd
authors.initials: DD
authors.lastname: Hamdan
authors.forename: Marilyn B
authors.initials: MB
authors.lastname: Renfree
authors.forename: Frank
authors.initials: F
authors.lastname: Grützner
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000032:analysis / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D008297:Male; D010987:Platypus / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D025721:WT1 Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C110547:DMRT1 protein; D014157:Transcription Factors; D025721:WT1 Proteins; D004265:DNA Helicases