Li HUANG,Mian ZHAO,Zhenhua LUO and Hua WU.Allelic Polymorphism, Gene Duplication and Balancing Selection of MHC Class IIB Genes in the Omei Treefrog (Rhacophorus omeimontis)[J].Asian Herpetological Research(AHR),2016,7(1):1-11.[doi:10.16373/j.cnki.ahr.150053]
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Allelic Polymorphism, Gene Duplication and Balancing Selection of MHC Class IIB Genes in the Omei Treefrog (Rhacophorus omeimontis)
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Asian Herpetological Research[ISSN:2095-0357/CN:51-1735/Q]

2016 VoI.7 No.1
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Allelic Polymorphism, Gene Duplication and Balancing Selection of MHC Class IIB Genes in the Omei Treefrog (Rhacophorus omeimontis)
Li HUANG# Mian ZHAO# Zhenhua LUO and Hua WU*
Institute of Evolution and Ecology, International Research Centre of Ecology and Environment, School of Life Sciences, Central China Normal University, 152 Luoyulu, Hongshan District, Wuhan 430079, China
MHC class IIB polymorphism gene duplication balancing selection Rhacophorus omeimontis
The worldwide declines in amphibian populations have largely been caused by infectious fungi and bacteria. Given that vertebrate immunity against these extracellular pathogens is primarily functioned by the major histocompatibility complex (MHC) class II molecules, the characterization and the evolution of amphibian MHC class II genes have attracted increasing attention. The polymorphism of MHC class II genes was found to be correlated with susceptibility to fungal pathogens in many amphibian species, suggesting the importance of studies on MHC class II genes for amphibians. However, such studies on MHC class II gene evolution have rarely been conducted on amphibians in China. In this study, we chose Omei treefrog (Rhacophorus omeimontis), which lived moist environments easy for breeding bacteria, to study the polymorphism of its MHC class II genes and the underlying evolutionary mechanisms. We amplified the entire MHC class IIB exon 2 sequence in the R. omeimontis using newly designed primers. We detected 102 putative alleles in 146 individuals. The number of alleles per individual ranged from one to seven, indicating that there are at least four loci containing MHC class IIB genes in R. omeimontis. The allelic polymorphism estimated from the 102 alleles in R. omeimontis was not high compared to that estimated in other anuran species. No significant gene recombination was detected in the 102 MHC class IIB exon 2 sequences. In contrast, both gene duplication and balancing selection greatly contributed to the variability in MHC class IIB exon 2 sequences of R. omeimontis. This study lays the groundwork for the future researches to comprehensively analyze the evolution of amphibian MHC genes and to assess the role of MHC gene polymorphisms in resistance against extracellular pathogens for amphibians in China.


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Last Update: 2016-03-30