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

Immunogenetics

By:
, , ,
DOI: 10.1007/s00251-010-0476-6

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Abstract

Genes encoded by the major histocompatibility complex (MHC) play key roles in the vertebrate immune system. However, our understanding of the evolutionary processes and underlying genetic mechanisms shaping these genes is limited in many taxa, including amphibians, a group currently impacted by emerging infectious diseases. To further elucidate the evolution of the MHC in frogs (anurans) and develop tools for population genetics, we surveyed allelic diversity of the MHC class II ??1 domain in both genomic and complementary DNA of seven New World species in the genus Rana (Lithobates). To assign locus affiliation to our alleles, we used a "gene walking" technique to obtain intron 2 sequences that flanked MHC class II?? exon 2. Two distinct intron sequences were recovered, suggesting the presence of at least two class II?? loci in Rana. We designed a primer pair that successfully amplified an orthologous locus from all seven Rana species. In total, we recovered 13 alleles and documented trans-species polymorphism for four of the alleles. We also found quantitative evidence of selection acting on amino acid residues that are putatively involved in peptide binding and structural stability of the ??1 domain of anurans. Our results indicated that primer mismatch can result in polymerase chain reaction (PCR) bias, which influences the number of alleles that are recovered. Using a single locus may minimize PCR bias caused by primer mismatch, and the gene walking technique was an effective approach for generating single-copy orthologous markers necessary for future studies of MHC allelic variation in natural amphibian populations. ?? 2010 Springer-Verlag.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Selection, trans-species polymorphism, and locus identification of major histocompatibility complex class II?? alleles of New World ranid frogs
Series title:
Immunogenetics
DOI:
10.1007/s00251-010-0476-6
Volume
62
Issue:
11-12
Year Published:
2010
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Immunogenetics
First page:
741
Last page:
751
Number of Pages:
11