Transcriptome analyses of immune tissues from three Japanese frogs (genus Rana) reveals their utility in characterizing major histocompatibility complex class II

BMC Genomics

Research Article

Takeshi Igawa¹  Ryuhei Minei²  Yoko Satta³  Quintin Lau³  Tiffany A. Kosch⁴ 

[1]Amphibian Research Center, Hiroshima University, 1-3-1, Higashi-Hiroshima, 739-8526, Hiroshima, Japan

[2]Department of Bioscience, Nagahama Institute of Bio-Science and Technology, Tamura-cho 1266, 526-0829, Nagahama, Shiga, Japan

[3]Department of Evolutionary Studies of Biosystems, Sokendai, The Graduate University for Advanced Studies, Kamiyamaguchi 1560-35, 240-0193, Hayama, Kanagawa, Japan

[4]One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, 4811, Townsville, QLD, Australia

关键词: Ranidae;    Chytridiomycosis;    MHC supertypes;    RNA-Seq;    Rana japonica;    Rana ornativentris;    Rana tagoi;    Antimicrobial peptides;   

DOI  :  10.1186/s12864-017-4404-0

 received in 2017-08-01, accepted in 2017-12-19,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundIn Japan and East Asia, endemic frogs appear to be tolerant or not susceptible to chytridiomycosis, a deadly amphibian disease caused by the chytrid fungus Batrachochytridium dendrobatidis (Bd). Japanese frogs may have evolved mechanisms of immune resistance to pathogens such as Bd. This study characterizes immune genes expressed in various tissues of healthy Japanese Rana frogs.ResultsWe generated transcriptome data sets of skin, spleen and blood from three adult Japanese Ranidae frogs (Japanese brown frog Rana japonica, the montane brown frog Rana ornativentris, and Tago’s brown frog Rana tagoi tagoi) as well as whole body of R. japonica and R. ornativentris tadpoles. From this, we identified tissue- and stage-specific differentially expressed genes; in particular, the spleen was most enriched for immune-related genes. A specific immune gene, major histocompatibility complex class IIB (MHC-IIB), was further characterized due to its role in pathogen recognition. We identified a total of 33 MHC-IIB variants from the three focal species (n = 7 individuals each), which displayed evolutionary signatures related to increased MHC variation, including balancing selection. Our supertyping analyses of MHC-IIB variants from Japanese frogs and previously studied frog species identified potential physiochemical properties of MHC-II that may be important for recognizing and binding chytrid-related antigens.ConclusionsThis is one of the first studies to generate transcriptomic resources for Japanese frogs, and contributes to further understanding the immunogenetic factors associated with resistance to infectious diseases in amphibians such as chytridiomycosis. Notably, MHC-IIB supertyping analyses identified unique functional properties of specific MHC-IIB alleles that may partially contribute to Bd resistance, and such properties provide a springboard for future experimental validation.

【 授权许可】

CC BY   
© The Author(s). 2017