title: Cone visual pigments in two species of South American marsupials.
abstract: Marsupials are largely confined to Australasia and to Central and South America. The visual pigments that underlie the photosensitivity of the retina have been examined in a number of species from the former group where evidence for trichromatic colour vision has been found, but none from the latter. In this paper, we report the cone opsin sequences from two nocturnal South American marsupial species, the gray short-tailed opossum, Monodelphis domestica, and the big-eared opossum, Didelphis aurita. Both are members of the Order Didelphimorphia (American opossums). For both species, only two classes of cone opsin were found, an SWS1 and an LWS sequence, and in vitro expression showed that the peak sensitivity of the SWS1 pigment is in the UV. Analysis of the Monodelphis genome confirms the absence of other classes of cone visual pigment genes. The SWS1 and LWS genes with 4 and 5 introns respectively, show the same exon-intron structure as found for these genes in all other vertebrates. The SWS1 gene shows a conserved synteny with flanking genes. The LWS gene is X-linked, as in all therian mammals so far examined, with a locus control region 1.54 kb upstream.
authors.affiliation: UCL Institute of Ophthalmology, London, UK. d.hunt@ucl.ac.uk
authors.forename: David M
authors.initials: DM
authors.lastname: Hunt
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Chan
authors.forename: Livia S
authors.initials: LS
authors.lastname: Carvalho
authors.forename: Jan N
authors.initials: JN
authors.lastname: Hokoc
authors.forename: Margo C
authors.initials: MC
authors.lastname: Ferguson
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Arrese
authors.forename: Lyn D
authors.initials: LD
authors.lastname: Beazley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D019901:Locus Control Region; D008394:Marsupialia; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics; D017949:Retinal Cone Photoreceptor Cells / Q000737:chemistry*; D012168:Retinal Pigments / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014466:Ultraviolet Rays
chemical_list: D017931:DNA Primers; D012168:Retinal Pigments; D012313:RNA