A HUMAN CANDIDATE SPERMATOGENESIS GENE, RBM1, IS CONSERVED AND AMPLIFIED ON THE MARSUPIAL Y-CHROMOSOME

Three genes, RBM1, DAZ and TSPY, map to a small region of the long arm of the human Y chromosome which is deleted in azoospermic men. RBM1, but not DAZ or TSPY, has a Y-linked homologue in marsupials which is t ranscribed in the testis. This suggests that RBM1 has been retained on the Y chromosome because of a critical male-specific function. Marsup ial RBM1 is closely related to human RBM1, but, like the related autos omal gene hnRNPG, lacks the amplification of an exon. This suggests th at RBM1 evolved from hnRNPG at least 130 million years ago and has und ergone internal amplification in primates, as well as independent ampl ification in several eutherian lineages.