title: The hypothalamic photoreceptors regulating seasonal reproduction in birds: a prime role for VA opsin.
abstract: Extraretinal photoreceptors located within the medio-basal hypothalamus regulate the photoperiodic control of seasonal reproduction in birds. An action spectrum for this response describes an opsin photopigment with a λmax of ∼ 492 nm. Beyond this however, the specific identity of the photopigment remains unresolved. Several candidates have emerged including rod-opsin; melanopsin (OPN4); neuropsin (OPN5); and vertebrate ancient (VA) opsin. These contenders are evaluated against key criteria used routinely in photobiology to link orphan photopigments to specific biological responses. To date, only VA opsin can easily satisfy all criteria and we propose that this photopigment represents the prime candidate for encoding daylength and driving seasonal breeding in birds. We also show that VA opsin is co-expressed with both gonadotropin-releasing hormone (GnRH) and arginine-vasotocin (AVT) neurons. These new data suggest that GnRH and AVT neurosecretory pathways are endogenously photosensitive and that our current understanding of how these systems are regulated will require substantial revision.
authors.affiliation: Departamento de Morfología y Biología Celular, Universidad de Oviedo, INEUROPA (Instituto de Neurociencias del Principado de Asturias), Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: García-Fernández
authors.affiliation: Departamento de Morfología y Biología Celular, Universidad de Oviedo, INEUROPA (Instituto de Neurociencias del Principado de Asturias), Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Cernuda-Cernuda
authors.affiliation: School of Animal Biology and University of Western Australia Oceans Institute, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Wayne I L
authors.initials: WI
authors.lastname: Davies
authors.affiliation: Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
authors.forename: Jessica
authors.initials: J
authors.lastname: Rodgers
authors.affiliation: Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Turton
authors.affiliation: Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
authors.forename: Stuart N
authors.initials: SN
authors.lastname: Peirson
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.eNuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Follett
authors.affiliation: Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Halford
authors.affiliation: Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
authors.forename: Steven
authors.initials: S
authors.lastname: Hughes
authors.affiliation: Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Hankins
authors.affiliation: Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom. Electronic address: russell.foster@eye.ox.ac.uk.
authors.forename: Russell G
authors.initials: RG
authors.lastname: Foster
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000502:physiology*; D001717:Birds / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis; D007031:Hypothalamus / Q000502:physiology*; D055355:Opsins / Q000502:physiology*; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D012621:Seasons; D012726:Sexual Behavior, Animal / Q000502:physiology*; D014668:Vasotocin / Q000096:biosynthesis
chemical_list: D030161:Avian Proteins; D055355:Opsins; D007987:Gonadotropin-Releasing Hormone; D014668:Vasotocin
keywords: Arginine-vasotocin (AVT); Birds; Gonadotropin-releasing hormone (GnRH); Hypothalamus; Neurosecretory; Opsin; Photoperiodism; Photopigment; Seasonal reproduction; VA opsin