title: An essential role of the arginine vasotocin system in mate-guarding behaviors in triadic relationships of medaka fish (Oryzias latipes).
abstract: To increase individual male fitness, males of various species remain near a (potential) mating partner and repel their rivals (mate-guarding). Mate-guarding is assumed to be mediated by two different types of motivation: sexual motivation toward the opposite sex and competitive motivation toward the same sex. The genetic/molecular mechanisms underlying how mate presence affects male competitive motivation in a triadic relationship has remained largely unknown. Here we showed that male medaka fish prominently exhibit mate-guarding behavior. The presence of a female robustly triggers male-male competition for the female in a triadic relationship (2 males and 1 female). The male-male competition resulted in one male occupying a dominant position near the female while interfering with the other male's approach of the female. Paternity testing revealed that the dominant male had a significantly higher mating success rate than the other male in a triadic relationship. We next generated medaka mutants of arginine-vasotocin (avt) and its receptors (V1a1, V1a2) and revealed that two genes, avt and V1a2, are required for normal mate-guarding behavior. In addition, behavioral analysis of courtship behaviors in a dyadic relationship and aggressive behaviors within a male group revealed that avt mutant males displayed decreased sexual motivation but showed normal aggression. In contrast, heterozygote V1a2 mutant males displayed decreased aggression, but normal mate-guarding and courtship behavior. Thus, impaired mate-guarding in avt and V1a2 homozygote mutants may be due to the loss of sexual motivation toward the opposite sex, and not to the loss of competitive motivation toward rival males. The different behavioral phenotypes between avt, V1a2 heterozygote, and V1a2 homozygote mutants suggest that there are redundant systems to activate V1a2 and that endogenous ligands activating the receptor may differ according to the social context.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Yokoi
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan; Laboratory of Bioresources, National Institute for Basic Biology, Okazaki, Aichi, Japan.
authors.forename: Teruhiro
authors.initials: T
authors.lastname: Okuyama
authors.affiliation: Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan; The Spectrography and Bioimaging Facility, National Institute for Basic Biology, Okazaki, Aichi, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kamei
authors.affiliation: Laboratory of Bioresources, National Institute for Basic Biology, Okazaki, Aichi, Japan; Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan; NIBB Center of the Interuniversity Bio-Backup Project, National Institute for Basic Biology, Okazaki, Aichi, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Naruse
authors.affiliation: Department of Public Health and Preventive Medicine, Kyorin University, School of Medicine, Mitaka, Tokyo, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Taniguchi
authors.affiliation: Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ansai
authors.affiliation: Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Center for Translational Social Neuroscience, Department of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Young
authors.affiliation: Proteo-Science Center, Division of Proteomics Research, Ehime University, Toon City, Ehime, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Takemori
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Kubo
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Takeuchi
mesh_terms: D000374:Aggression / Q000502:physiology; D000818:Animals; D003307:Copulation / Q000502:physiology; D005260:Female; D008297:Male; D008393:Marriage; D009042:Motivation / Q000502:physiology; D009990:Oryzias / Q000235:genetics* / Q000502:physiology; D012098:Reproduction / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology*; D014668:Vasotocin / Q000235:genetics* / Q000378:metabolism
chemical_list: D014668:Vasotocin