New exon and accelerated evolution of placental gene Nrk occurred in the ancestral lineage of placental mammals

The chorioallantoic placenta is a specific organ for placental mammals. However, the adaptive events during its emergence are still poorly investigated.We scanned the chromosome X to detect the accelerated evolution in the ancestral lineage of placental mammals, and constructed 3D protein structure models of a candidate by homology modeling.Eight branch-specific accelerated regions were identified. Five of these regions (P=5.61×10-11 ~...