Selection, trans-species polymorphism, and locus identification of major histocompatibility complex class IIβ alleles of New World ranid frogs.

摘要: Genes encoded by the major histocompatibility complex (MHC) play key roles in vertebrate immune system. However, our understanding of evolutionary processes and underlying genetic mechanisms shaping these genes is limited many taxa, including amphibians, a group currently impacted emerging infectious diseases. To further elucidate evolution MHC frogs (anurans) develop tools for population genetics, we surveyed allelic diversity class II β1 domain both genomic complementary DNA seven New World species genus Rana (Lithobates). assign locus affiliation to alleles, used “gene walking” technique obtain intron 2 sequences that flanked IIβ exon 2. Two distinct were recovered, suggesting presence at least two loci Rana. We designed primer pair successfully amplified an orthologous from all species. In total, recovered 13 alleles documented trans-species polymorphism four alleles. also found quantitative evidence selection acting on amino acid residues are putatively involved peptide binding structural stability anurans. Our results indicated mismatch can result polymerase chain reaction (PCR) bias, which influences number recovered. Using single may minimize PCR bias caused mismatch, gene walking was effective approach generating single-copy markers necessary future studies variation natural amphibian populations.