title: The MC1R and ASIP Coat Color Loci May Impact Behavior in the Horse.
abstract: Shared signaling pathways utilized by melanocytes and neurons result in pleiotropic traits of coat color and behavior in many mammalian species. For example, in humans polymorphisms at MC1R cause red hair, increased heat sensitivity, and lower pain tolerance. In deer mice, rats, and foxes, ASIP polymorphisms causing black coat color lead to more docile demeanors and reduced activity. Horse (Equus caballus) base coat color is primarily determined by polymorphisms at the Melanocortin-1 Receptor (MC1R) and Agouti Signaling Protein (ASIP) loci, creating a black, bay, or chestnut coat. Our goal was to investigate correlations between genetic loci for coat color and temperament traits in the horse. We genotyped a total of 215 North American Tennessee Walking Horses for the 2 most common alleles at the MC1R (E/e) and ASIP (A/a) loci using previously published PCR and RFLP methods. The horses had a mean age of 10.5 years and comprised 83 geldings, 25 stallions, and 107 mares. To assess behavior, we adapted a previously published survey for handlers to score horses from 1 to 9 on 20 questions related to specific aspects of temperament. We utilized principle component analysis to combine the individual survey scores into 4 factors of variation in temperament phenotype. A factor component detailing self-reliance correlated with genotypes at the ASIP locus; black mares (aa) were more independent than bay mares (A_) (P = 0.0063). These findings illuminate a promising and novel animal model for future study of neuroendocrine mechanisms in complex behavioral phenotypes.
authors.affiliation: From the Department of Animal Science, Cornell University, Morrison Hall, Ithaca, NY 14853 (Jacobs and Staiger); Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, Knoxville, TN 37996 (Albright); Department of Animal Science, University of Florida, PO Box 110910, Gainesville, FL 32611 (Brooks).
authors.forename: Lauren N
authors.initials: LN
authors.lastname: Jacobs
authors.affiliation: From the Department of Animal Science, Cornell University, Morrison Hall, Ithaca, NY 14853 (Jacobs and Staiger); Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, Knoxville, TN 37996 (Albright); Department of Animal Science, University of Florida, PO Box 110910, Gainesville, FL 32611 (Brooks).
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Staiger
authors.affiliation: From the Department of Animal Science, Cornell University, Morrison Hall, Ithaca, NY 14853 (Jacobs and Staiger); Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, Knoxville, TN 37996 (Albright); Department of Animal Science, University of Florida, PO Box 110910, Gainesville, FL 32611 (Brooks).
authors.forename: Julia D
authors.initials: JD
authors.lastname: Albright
authors.affiliation: From the Department of Animal Science, Cornell University, Morrison Hall, Ithaca, NY 14853 (Jacobs and Staiger); Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, Knoxville, TN 37996 (Albright); Department of Animal Science, University of Florida, PO Box 110910, Gainesville, FL 32611 (Brooks). samantha.brooks@ufl.edu.
authors.forename: Samantha A
authors.initials: SA
authors.lastname: Brooks
mesh_terms: D054366:Agouti Signaling Protein / Q000235:genetics*; D000483:Alleles; D000818:Animals; D001522:Behavior, Animal; D001947:Breeding; D005260:Female; D005787:Gene Frequency; D056426:Genetic Loci; D005838:Genotype; D006200:Hair Color / Q000235:genetics*; D006736:Horses / Q000235:genetics* / Q000502:physiology; D008297:Male; D025341:Principal Component Analysis; D044102:Receptor, Melanocortin, Type 1 / Q000235:genetics*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D013694:Temperament
chemical_list: D054366:Agouti Signaling Protein; D044102:Receptor, Melanocortin, Type 1
keywords: ASIP; MC1R; equine; pigmentation; temperament