title: Cryptochrome 1 in Retinal Cone Photoreceptors Suggests a Novel Functional Role in Mammals.
abstract: Cryptochromes are a ubiquitous group of blue-light absorbing flavoproteins that in the mammalian retina have an important role in the circadian clock. In birds, cryptochrome 1a (Cry1a), localized in the UV/violet-sensitive S1 cone photoreceptors, is proposed to be the retinal receptor molecule of the light-dependent magnetic compass. The retinal localization of mammalian Cry1, homologue to avian Cry1a, is unknown, and it is open whether mammalian Cry1 is also involved in magnetic field sensing. To constrain the possible role of retinal Cry1, we immunohistochemically analysed 90 mammalian species across 48 families in 16 orders, using an antiserum against the Cry1 C-terminus that in birds labels only the photo-activated conformation. In the Carnivora families Canidae, Mustelidae and Ursidae, and in some Primates, Cry1 was consistently labeled in the outer segment of the shortwave-sensitive S1 cones. This finding would be compatible with a magnetoreceptive function of Cry1 in these taxa. In all other taxa, Cry1 was not detected by the antiserum that likely also in mammals labels the photo-activated conformation, although Western blots showed Cry1 in mouse retinal cell nuclei. We speculate that in the mouse and the other negative-tested mammals Cry1 is involved in circadian functions as a non-light-responsive protein.
authors.affiliation: Max Planck Institute for Brain Research, Max-von-Laue-Str. 4, 60438 Frankfurt am Main, Germany.|Department of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich, Theresienstr. 41, 80333 Munich, Germany.|Ernst Strüngmann Insitute for Neuroscience, Deutschordenstr. 46, 60528 Frankfurt am Main, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Nießner
authors.affiliation: Department of Biosciences, Goethe University Frankfurt am Main, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Denzau
authors.affiliation: Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany.|Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, 165 21 Praha 6 - Suchdol, Czech Republic.
authors.forename: Erich Pascal
authors.initials: EP
authors.lastname: Malkemper
authors.affiliation: Department of Hematology/Oncology and Developmental Biochemistry, University Medicine, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
authors.forename: Julia Christina
authors.initials: JC
authors.lastname: Gross
authors.affiliation: Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany.|Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, 165 21 Praha 6 - Suchdol, Czech Republic.
authors.forename: Hynek
authors.initials: H
authors.lastname: Burda
authors.affiliation: Department of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich, Theresienstr. 41, 80333 Munich, Germany.|Institute for Biology and Environmental Sciences IBU, University of Oldenburg, 26111 Oldenburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Winklhofer
authors.affiliation: Max Planck Institute for Brain Research, Max-von-Laue-Str. 4, 60438 Frankfurt am Main, Germany.|Ernst Strüngmann Insitute for Neuroscience, Deutschordenstr. 46, 60528 Frankfurt am Main, Germany.
authors.forename: Leo
authors.initials: L
authors.lastname: Peichl
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology; D046028:Canidae / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects; D055358:Cone Opsins / Q000235:genetics; D056931:Cryptochromes / Q000737:chemistry / Q000235:genetics*; D015870:Gene Expression; D015186:Hominidae / Q000502:physiology; D007106:Immune Sera / Q000737:chemistry; D007150:Immunohistochemistry; D008027:Light; D060526:Magnetic Fields; D008322:Mammals / Q000145:classification / Q000502:physiology*; D045969:Mustelidae / Q000502:physiology; D010802:Phylogeny; D011487:Protein Conformation; D000072417:Protein Domains; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology* / Q000528:radiation effects / Q000648:ultrastructure; D001503:Ursidae / Q000502:physiology
chemical_list: D055358:Cone Opsins; D056931:Cryptochromes; D007106:Immune Sera