The growth hormone gene has evolved independently in African Pygmy Mouse Mus minutoides

Mus minutoides (the African pygmy mouse) is one of the smallest mammals. We determined the nucleotide sequence of the growth hormone (Gh) gene and the sequence of the putative coding region in M. minutoides, where is predicted to be distinct in the functional and transcriptional regulatory regions between M. minutoides and Mus musculus (the House mouse). To investigate the evolutionary characteristics of Gh in M. minutoides, we constructed a phylogenetic tree based on the putative amino acid sequences of Gh in M. musculus and mammals by neighbor-joining method, suggesting that Gh diverged relatively earlier than other Mus genus and may have evolved independently in M. minutoides. Furthermore, analysis of Gh gene expression levels showed a tendency to be higher in M. minutoides than in M. musculus. Our results suggest that Gh may have evolved independently in M. minutoides and may have different functions and signaling in Mus genus.