title: Overdominance effect of the bovine ghrelin receptor (GHSR1a)-DelR242 locus on growth in Japanese Shorthorn weaner bulls: heterozygote advantage in bull selection and molecular mechanisms.
abstract: Ghrelin and the ghrelin receptor (GHSR1a) are involved in growth hormone secretion, food intake, and several other important functions. Ghrelin acts on GHSR1a and induces signal transduction via the Gαq subunit. In our previous study, we identified the DelR242 (3R) allele, a truncated 3-arginine residue (3R) [major type: 4 arginine residues (4R)] of the third intracellular loop of GHSR1a, with a high frequency in Japanese Shorthorn bulls (0.43) but with a low frequency in other cattle breeds (0.00-0.09). To further investigate the reasons for the higher frequency of the 3R allele, we performed several experiments. In this study, we found a significant sex difference in the frequency of the 3R allele. Statistical analysis revealed a significant overdominance effect of the DelR242 locus on growth in Japanese Shorthorn weaner bulls. However, additive/dominance/overdominance effects of the 3R allele on carcass traits in adult steers and dams were not significant. The mode of the overdominance effect was estimated to be solely controlled by the single DelR242 locus without any other linked loci using linkage disequilibrium analysis in GHSR1a. These results indicated that 4R/3R heterozygotes had a selective advantage in weaner bulls because of their higher average daily gain than homozygotes. We discussed possible molecular mechanisms involved in the overdominance effect of the DelR242 locus on these traits in weaner bulls using a structural model of the complex consisting of a GHSR1a dimer and Gαq.
authors.affiliation: Animal Breeding Research Group, NARO Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0901, Japan mkomatsu@affrc.go.jp.
authors.forename: Masanori
authors.identifier: http://orcid.org/0000-0002-8545-193X
authors.initials: M
authors.lastname: Komatsu
authors.affiliation: Animal Industry Research Institute, Iwate Agricultural Research Center (IARC), Takizawa, Iwate 020-0173, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Negami
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan Agricultural Bioinformatics Research Unit, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Terada
authors.affiliation: Animal Breeding Research Group, NARO Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0901, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Sasaki
authors.affiliation: Animal Industry Research Institute, Iwate Agricultural Research Center (IARC), Takizawa, Iwate 020-0173, Japan.
authors.forename: Jumpei
authors.initials: J
authors.lastname: Yasuda
authors.affiliation: Animal Research Group, National Institute of Agrobiological Sciences, Ikenodai 2, Tsukuba, Ibaraki 305-0901, Japan.
authors.forename: Aisaku
authors.initials: A
authors.lastname: Arakawa
authors.affiliation: Animal Industry Research Institute, Iwate Agricultural Research Center (IARC), Takizawa, Iwate 020-0173, Japan.
authors.forename: Chikara
authors.initials: C
authors.lastname: Yoshida
authors.affiliation: Animal Breeding Research Group, NARO Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0901, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Animal Science and Genetics, Tasmanian Institute of Agriculture, School of Land & Food, Faculty of Science, Engineering and Technology, University of Tasmania, Hobart, Tasmania TAS 7001, Australia Veterinary and Biomedical Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland QLD 4811, Australia.
authors.forename: Aduli E O
authors.initials: AE
authors.lastname: Malau-Aduli
authors.affiliation: Graduate School of Agriculture, Tohoku University, Sendai, Miyagi 981-8555, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan Agricultural Bioinformatics Research Unit, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D002417:Cattle / Q000235:genetics* / Q000254:growth & development; D005260:Female; D005787:Gene Frequency; D006239:Haplotypes; D006579:Heterozygote; D015810:Linkage Disequilibrium; D008297:Male; D009154:Mutation; D054440:Receptors, Ghrelin / Q000235:genetics*; D012727:Sex Characteristics
chemical_list: D054440:Receptors, Ghrelin
keywords: DelR242; cattle; ghrelin receptor (GHSR1a); growth; overdominance