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

Lau, Quintin, Igawa, Takeshi, Minei, Ryuhei, Kosch, Tiffany A., and Satta, Yoko (2017) Transcriptome analyses of immune tissues from three Japanese frogs (genus Rana) reveals their utility in characterizing major histocompatibility complex class II. BMC Genomics, 18.

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Background: In 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.

Results: We 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 stagespecific 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.

Conclusions: This 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.

Item ID: 52145
Item Type: Article (Research - C1)
ISSN: 1471-2164
Keywords: Ranidae, Chytridiomycosis, MHC supertypes, RNA-Seq, Rana japonica, Rana ornativentris, Rana tagoi, antimicrobial peptides
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This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Funders: Japan Society for Promotion of Science (JSPS), Australian Academy of Science (AAS)
Projects and Grants: JSPS (AAS) postdoctoral research fellowship
Date Deposited: 24 Jan 2018 07:31
FoR Codes: 31 BIOLOGICAL SCIENCES > 3109 Zoology > 310902 Animal cell and molecular biology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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