title: A mammalian neural tissue opsin (Opsin 5) is a deep brain photoreceptor in birds.
abstract: It has been known for many decades that nonmammalian vertebrates detect light by deep brain photoreceptors that lie outside the retina and pineal organ to regulate seasonal cycle of reproduction. However, the identity of these photoreceptors has so far remained unclear. Here we report that Opsin 5 is a deep brain photoreceptive molecule in the quail brain. Expression analysis of members of the opsin superfamily identified as Opsin 5 (OPN5; also known as Gpr136, Neuropsin, PGR12, and TMEM13) mRNA in the paraventricular organ (PVO), an area long believed to be capable of phototransduction. Immunohistochemistry identified Opsin 5 in neurons that contact the cerebrospinal fluid in the PVO, as well as fibers extending to the external zone of the median eminence adjacent to the pars tuberalis of the pituitary gland, which translates photoperiodic information into neuroendocrine responses. Heterologous expression of Opsin 5 in Xenopus oocytes resulted in light-dependent activation of membrane currents, the action spectrum of which showed peak sensitivity (lambda(max)) at approximately 420 nm. We also found that short-wavelength light, i.e., between UV-B and blue light, induced photoperiodic responses in eye-patched, pinealectomized quail. Thus, Opsin 5 appears to be one of the deep brain photoreceptive molecules that regulates seasonal reproduction in birds.
authors.affiliation: Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakane
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ikegami
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ono
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Shosei
authors.initials: S
authors.lastname: Yoshida
authors.forename: Kanjun
authors.initials: K
authors.lastname: Hirunagi
authors.forename: Shizufumi
authors.initials: S
authors.lastname: Ebihara
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kubo
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D003370:Coturnix / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008473:Median Eminence / Q000033:anatomy & histology / Q000502:physiology; D008959:Models, Neurological; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D009865:Oocytes / Q000378:metabolism; D055355:Opsins / Q000235:genetics / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000033:anatomy & histology / Q000502:physiology; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000254:growth & development; D014982:Xenopus laevis
chemical_list: D030161:Avian Proteins; D009419:Nerve Tissue Proteins; D055355:Opsins; D011994:Recombinant Proteins