No differences in the Sry gene between males and XY females in Akodon (Rodentia, Cricetidae).

Several species of the South American genus Akodon present fully fertile XY females besides XX ones. To analyze the possibility of a Sry mutation as the cause of sex reversal in A. azarae and A. boliviensis, we determined the sequence of the Sry gene in 2 males and 3 XY females from each of these species. The Sry gene sequence was also studied in A. dolores, a species that does not have XY females. In inter-specific comparisons, the percentage identities with respect to the region analyzed varied between 96.8% and 97.9%. An ORF of 543 nucleotides was identified, and the predicted Sry proteins comprised 180 amino acids, with an HMG domain of 83 amino acids. Our results indicate that female sex reversal in A. azarae and A. boliviensis cannot be explained by sequence differences in the Sry region analyzed here, which includes the complete ORF and, together with previous results concerning the inheritance of the XY condition, show that Sry mutation is not the basis of sex reversal.