title: Rainbow trout eyed-stage embryos demonstrate melatonin rhythms under light-dark conditions as measured by a newly developed time-resolved fluoroimmunoassay.
abstract: Melatonin contents in eyed-stage embryos of rainbow trout (Oncorhynchus mykiss) were measured by a newly developed, highly sensitive, and nonisotopic immunoassay method: time-resolved fluoroimmunoassay (TR-FIA). The melatonin-bovine serum albumin (BSA) conjugate was immobilized by physical adsorption to the wells of microtiter plates. A competitive assay using two antibodies was performed among melatonin-BSA in the solid phase, samples, melatonin antibodies, and europium-labeled secondary antibodies. The system showed a sensitivity of 0.6 pg/well. The embryos showed clear melatonin rhythms under a 12L:12D photo cycle. Although the melatonin was detected in the egg yolk, the quantities were the same in both the light and dark phases. These results indicate that the melatonin secretion system has already functioned at least from the eyed-stage embryo in rainbow trout.
authors.affiliation: School of Fisheries Sciences, Kitasato University, Sanriku, Iwate 022-0101, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yamada
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Chiba
authors.forename: Masafumi
authors.initials: M
authors.lastname: Amano
authors.forename: Masayuki
authors.initials: M
authors.lastname: Iigo
authors.forename: Munehico
authors.initials: M
authors.lastname: Iwata
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D003624:Darkness; D004530:Egg Yolk / Q000737:chemistry; D004625:Embryo, Nonmammalian / Q000378:metabolism* / Q000502:physiology; D005123:Eye / Q000196:embryology*; D005260:Female; D015200:Fluoroimmunoassay; D007202:Indicators and Reagents; D008027:Light; D008550:Melatonin / Q000032:analysis / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000196:embryology*
chemical_list: D007202:Indicators and Reagents; D008550:Melatonin