Breed Differences in Dopamine Receptor D4 Gene (DRD4) in Horses.
Abstract: Genetic polymorphisms in genes related to neurotransmitters or hormones affect personality or behavioral traits in many animal species including humans. In domestic animals, the allele frequency of such genes has been reported to be different among breeds and it may account for breed differences in behavior. In this study, we investigated breed differences in horses in the dopamine receptor D4 gene (DRD4), which has been reported to affect horse personality. We collected samples from seven horse breeds including those native to Japan and Korea, and compared the sequence of the DRD4 exon3 region among these breeds. We found that there were two types of polymorphisms (VNTR and SNPs) in the exon3 region, and some of them seemed to be breed-specific. In addition, we found that the allele frequency of G292A, reported to be associated with horse personality, differed greatly between native Japanese horses and Thoroughbred horses. The frequency of the A allele which is associated with low curiosity and high vigilance, was much lower in native Japanese horses (Hokkaido, 0.03; Taishu, 0.08) than in Thoroughbreds (0.62). This difference may account for breed differences in personality or behavioral traits. Further studies of the function of these polymorphisms and their effect on behavior are indicated.
Publication Date: 2013-09-30 PubMed ID: 24833999PubMed Central: PMC4013985DOI: 10.1294/jes.24.31Google Scholar: Lookup
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- Journal Article
Summary
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This study scrutinizes the differences in the dopamine receptor D4 gene (DRD4) across various horse breeds. Significant variations in the gene, which has been associated with equine behavior, were discovered among different breeds, possibly explaining distinct behavioral traits.
Investigation Overview
- The research focused on the breed variances seen in horses in the dopamine receptor D4 gene, recognized for its influence on horse behavior, looking especially at native Japanese and Korean breeds and Thoroughbreds.
- The scientists collected genetic material from seven different horse breeds
- They then compared the sequence of the DRD4 exon3, an important region of this gene, across all these breeds
Findings and Discoveries
- The researchers identified two kinds of polymorphisms (variations in a genetic sequence that exist among individuals) in the exon3 region of the DRD4 gene. Polymorphism types identified are Variable Number Tandem Repeat (VNTR) and Single Nucleotide Polymorphisms (SNPs).
- Some of these variations appeared to be breed-specific, occurring only in certain breeds and leading to potential breed-specific behavioral traits.
- Specifically, the scientists discovered significant allele frequency differences for the G292A polymorphism, connected with equine behavior, between the native Japanese breeds and Thoroughbred horses.
Significance of Allele Frequency in Horse Personality
- Alleles are multiple forms of the same gene that occur in the same place on a chromosome.
- G292A is a mutation in the DRD4 gene that changes the base (building block of DNA) from a G (Guanine) to an A (Adenine).
- The “A” allele of this mutation is linked to low curiosity and high vigilance in horse behavior.
- Thoroughbred horses exhibited a higher frequency (0.62) of the “A” allele compared to the much lower frequencies seen in native Japanese horses: Hokkaido’s 0.03 and Taishu’s 0.08.
- These frequency differences suggest that DRD4 gene polymorphisms could underlie breed-specific behavioral traits.
Implications and Future Work
- The research indicates a correlation between the breed of the horse and specific alleles present in the DRD4 gene, providing a genetic basis for different behavioral patterns observed across horse breeds.
- The work suggests scope for further research into how these particular polymorphisms affect behavior, enabling better understanding and potential manipulation of animal behavior for various benefits including breeding, training, and animal welfare.
Cite This Article
APA
Hori Y, Ozaki T, Yamada Y, Tozaki T, Kim HS, Takimoto A, Endo M, Manabe N, Inoue-Murayama M, Fujita K.
(2013).
Breed Differences in Dopamine Receptor D4 Gene (DRD4) in Horses.
J Equine Sci, 24(3), 31-36.
https://doi.org/10.1294/jes.24.31 Publication
Researcher Affiliations
- Department of Psychology, Graduate School of Letters, Kyoto University, Sakyo, Kyoto 606-8501, Japan ; Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo 102-0083, Japan.
- Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan.
- Hokusho Agricultural High School, Hirado, Nagasaki 859-4824, Japan.
- Laboratory of Racing Chemistry, Utsunomiya, Tochigi 320-0851, Japan.
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Pusan 609-735, Korea.
- Department of Psychology, Graduate School of Letters, Kyoto University, Sakyo, Kyoto 606-8501, Japan ; Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo 102-0083, Japan.
- Animal Resource Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Kasama, Ibaraki 319-0206, Japan.
- Animal Resource Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Kasama, Ibaraki 319-0206, Japan.
- Wildlife Research Center, Kyoto University, Sakyo, Kyoto 606-8203, Japan.
- Department of Psychology, Graduate School of Letters, Kyoto University, Sakyo, Kyoto 606-8501, Japan.
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Citations
This article has been cited 4 times.- Kim J, Jung H, Choi JY, Lee JW, Yoon M. Plasma concentration of dopamine varies depending on breed, sex, and the genotype of DRD4 in horses. J Anim Sci Technol 2022 Jul;64(4):792-799.
- Schrimpf A, Single MS, Nawroth C. Social Referencing in the Domestic Horse. Animals (Basel) 2020 Jan 18;10(1).
- Hannan MA, Haneda S, Itami Y, Wachi S, Saitoh T, Cheong SH, Nambo Y. Successful embryo transfer from Hokkaido native pony after artificial insemination with frozen semen. J Vet Med Sci 2019 Feb 19;81(2):241-244.
- Valente TS, Baldi F, Sant'Anna AC, Albuquerque LG, Paranhos da Costa MJ. Genome-Wide Association Study between Single Nucleotide Polymorphisms and Flight Speed in Nellore Cattle. PLoS One 2016;11(6):e0156956.
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