LAUSR

ABSTRACT Amphibians, as the first terrestrial vertebrates, offer a window into early major histocompatibility complex (MHC) evolution. We characterized the MHC class I of two Korean amphibians, the Asiatic toad (Bufo gargarizans) and the Japanese tree frog (Hyla japonica). We found at least four transcribed MHC class I (MHC I) loci, the highest number confirmed in any anuran to date. Furthermore, we identified MHC I transcripts in terrestrial adults, and possibly in aquatic larvae, of both species. We conducted a phylogenetic analysis based on MHC I sequence data and found that B. gargarizans and H. japonica cluster together in the superfamily Nobleobatrachia. We further identified three supertypes shared by the two species. Our results reveal substantial variation in the number of MHC I loci in anurans and suggest that certain supertypes have particular physiochemical properties that may confer pathogen resistance. HIGHLIGHTSWe describe, for the first time, sequences of MHC class I from the Asian frogs Bufo gargarizans and Hyla japonica.We found at least four transcribed MHC class I loci in each species.MHC I transcription was found in larvae as well as adults.The two species shared supertypes based on their MHC I sequences.