| Pancreatic ribonuclease, encoded by gene RNASE1 is secreted protein, which secreted by pancreas. It only exists in vertebrates and has functions of digestion. Pancreatic ribonuclease, expressing with a high level and duplicating in ruminants indicates that it has a relationship with the digestive system. As it has ability of degrading dsRNA (double strands RNA), the expression in non-ruminants explains that it also related to immune function. But the functions of pancreatic ribonuclease are still not very clear. After gene duplication events, gene RNASE1 in leaf-eating monkeys produced its sister gene RNASE1B. Differentiation of functions of gene RNASEl and RNASE1B gave us a very good example to understand the adaptive evolution of functional genes. Chiroptera, which is also known as bats, is the second biggest mammal group of the world, and the rodents are the biggest. Evolution makes the food habit of bats diversification, and fish-eating bat is a new group which includes only four bats species, Noctilio leporinus, Noctilio albiventris, Myotis vivesi and Myotis ricketti. To see the evolution of gene RNASE1 in bats and the adaptive evolution in fish-eating bats, we cloned and analyzed the full-length encoding region of gene RNASEl from 21 different species of Vespertilionidae. This research showed that the gene duplication event of gene RNASE1 happened in Myotis, Vespertilionidae. It produced three sister gene copies, and we named them A, B and C respectively. Gene copy A undergone an accelerated evolution, and the sequences aligning showed that Gene copy A accumulated considerable amino substitutions comparing to Gene copy B and Gene copy C, which have a potential effect on the function of Gene copy A. These evidences indicate that Gene copy A may emerge novel functions. These three gene copies show accelerated evolution in species of Myotis indicated that gene RNASEl has not at the end of the evolutional procedure, and its functions are not completely stabilized.
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