| Connexin30, encoded by gene GJB6 is member of the family of gap junction proteins, which facilitate a process called gap junctional communication in vertebrates. Connexin30 plays a crucial role in hearing. Mutations in GJB6 are related to hearing loss and skin disease, such as Keratitis-ichthyosis-deafness (KID), nonsyndromic autosomal dominant deafness and hidrotic ectodermal dysplasia (HED). Chiroptera, which is also known as bats, is the only group with true flight capabilities and use ultrasonic echolocation for orientation and preying. It is also the second biggest mammal group of the world, and the rodents are the biggest. To investigate the evolution of GJB6 in mammals and test if this gene contributes to hearing in bats, we cloned the full-length coding region of GJB6 from 16 species of bats and 4 other mammal species and compared them to 11 orthologous sequences of mammals. We analyzed the evolution of GJB6 in mammals and the bat lineage using the maximum likelihood method. We also constructed gene trees using Bayesian and maximum likelihood methods. The results show purifying selection on GJB6 in mammals, as well as in the bat lineage, which indicates the important role of GJB6 in mammal hearing. However, compared with one unique amino acid substitution shared by 16 species of bats, we found ten unique amino acids substitutions shared by two species of artiodactyls which positioned the artiodactyls at an abnormal location in the gene tree. In addition, the cytoplasmic loop and carboxy terminus were more variable than other domains in all the mammals.
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