title: HIOMT-like immunoreactivity in the vertebrate retina: a species comparison.
abstract: Localization of the melatonin-synthesizing enzyme, hydroxyindole-O-methyltransferase (HIOMT)-like immunoreactivity was examined by light and electron microscopic immunocytochemistry, in the retinas of several species that have been used as animal models to study the retinal melatonin system. HIOMT-like immunoreactivity was observed in the retinal photoreceptors of rabbit, pigmented rat, guinea-pig, chick, goldfish. African clawed toad, and leopard frog. Additionally, most species displayed HIOMT immunoreactivity in a population of bipolar cells in the inner nuclear layer. At the ultrastructural level, HIOMT-like immunoreactivity was localized to the cytoplasm of rod and cone photoreceptors, and a population of cone bipolar cells. These observations are identical to earlier observations in the human retina. The similar pattern of HIOMT-like immunoreactivity among species suggests a phylogenetic conservation of the melatonin-synthesizing capability of retinal photoreceptors and some bipolar cells.
authors.affiliation: Department of Neurobiology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27103.
authors.forename: A F
authors.initials: AF
authors.lastname: Wiechmann
authors.forename: J G
authors.initials: JG
authors.lastname: Hollyfield
mesh_terms: D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism*; D000818:Animals; D002645:Chickens; D006054:Goldfish; D006168:Guinea Pigs; D008550:Melatonin / Q000096:biosynthesis; D008780:Methyltransferases / Q000378:metabolism*; D008854:Microscopy, Electron; D011817:Rabbits; D011894:Rana pipiens; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000201:enzymology* / Q000648:ultrastructure; D013045:Species Specificity; D014982:Xenopus laevis
chemical_list: D008780:Methyltransferases; D000121:Acetylserotonin O-Methyltransferase; D008550:Melatonin