title: Nature's knockout: the Mel1b receptor is not necessary for reproductive and circadian responses to melatonin in Siberian hamsters.
abstract: The pineal hormone melatonin regulates seasonal reproduction and influences the timing of circadian rhythms. The Mel1a and Mel1b receptors are the high-affinity melatonin receptors present in mammals. Unexpectedly, the Mel1b receptor gene of the Siberian hamster, Phodopus sungorus, cannot encode a functional receptor; two nonsense mutations are present within the coding region. Southern blot analysis indicates that this is a single copy gene. The Mel1b receptor gene is nonfunctional in outbred populations of P. sungorus and Phodopus campbelli. Siberian hamsters lacking a functional Mel1b receptor nevertheless show seasonal reproductive and circadian responses to melatonin, indicating that the Mel1b receptor is not necessary for these responses. These data support the hypothesis that the Mel1a receptor, which does encode a functional receptor in this species, mediates reproductive and circadian responses to melatonin.
authors.affiliation: Laboratory of Developmental Chronobiology, Massachusetts General Hospital, Boston, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Weaver
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.forename: S M
authors.initials: SM
authors.lastname: Reppert
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001947:Breeding; D002940:Circadian Rhythm / Q000187:drug effects*; D006224:Cricetinae; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009154:Mutation; D017111:Phodopus / Q000235:genetics / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000502:physiology; D044094:Receptors, Melatonin; D012098:Reproduction / Q000502:physiology*; D012621:Seasons; D017386:Sequence Homology, Amino Acid
chemical_list: D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D044094:Receptors, Melatonin; D008550:Melatonin