Comparative cytogenetic and molecular studies of DM domain genes in pig and cattle

Despite great differences in the biology of sex determination, the DM domain genes are thought to regulate sexual development in both invertebrates and vertebrates. Although they seem to represent the first known example of the conservation of metazoan sexual pathways, the structure-function relationships of this gene family have not yet been clearly determined. Our previous and current studies on the DMRT (Doublesex and mab-3 related transcription factor) gene cluster, DMRT1, DMRT2, DMRT3, in pig and cattle, have revealed conserved linkage to bovine (BTA8q17) and swine (SSC1q21) autosomes. However, the DMRT cluster seems to harbour the genes in different orders in both cattle (Entrez database) and pig (IMpRH map), compared to other vertebrates investigated so far. Moreover, we found that expression of DMRT1 (considered as the testicular regulator so far) is not restricted to gonads in adult animals. Beside ovary and testis, DMRT1 expression was detectable in swine kidney and bovine liver, heart, skeletal muscle, kidney, lung, spleen and showed no differences between the sexes. Swine and bovine DMRT3 expression was strongly restricted to the adult testis, while DMRT2 homologues have a wider expression pattern, as occurs in other mammals. The significance of this expression pattern of DMRT genes in adult pig and cattle remains unclear. It might shed new light on mammalian DM domain genes evolution and livestock intersexuality.