Biomaterial Database

Localization and characterization of [125I]iodomelatonin binding sites in duck gonads. 1994

E A Ayre, and Z P Wang, and G M Brown, and S F Pang

Department of Animal Science, Faculty of Agricultural Sciences, University of British Columbia, Vancouver, Canada.

The characterization and localization of [125I]iodomelatonin binding sites in the gonads advances the understanding of possible regulatory sites of melatonin action. With the availability of [125I]iodomelatonin as a biologically active radioligand, our study utilized a combined approach of autoradiography for anatomical resolution together with an established radioligand binding assay to assess mid-light [125I]iodomelatonin binding in the testes and ovaries of ducks. In the autoradiography study, specific [125I]iodomelatonin binding was shown to be homogeneous throughout the testes, while in the ovaries, specific [125I]iodomelatonin binding appeared to be concentrated around the follicle. Radioligand binding assay results indicated a single class of binding sites with the maximum number of [125I]iodomelatonin binding sites measured at 1.91 +/- 0.70 fmol/mg protein in testicular membrane and 4.54 +/- 0.64 fmol/mg protein in ovarian membrane. [125I]Iodomelatonin binding affinity, characterized by equilibrium dissociation constants of 29 +/- 6 pmol/L in testicular membrane and 53 +/- 9 pmol/L in ovarian membrane, was in accordance with circulating melatonin levels, suggesting an appropriate concentration for eliciting a physiological response. [125I]Iodomelatonin binding in duck gonads satisfied all the criteria for a binding site, being rapid, stable, saturable, reversible, specific, and of high affinity, and may indicate a direct pineal-gonadal connection.

UI	MeSH Term	Description	Entries
D007457	Iodine Radioisotopes	Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.	Radioisotopes, Iodine
D008297	Male		Males
D008550	Melatonin	A biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the PINEAL GLAND. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of SLEEP, mood, and REPRODUCTION. Melatonin is also an effective antioxidant.
D010053	Ovary	The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.	Ovaries
D011869	Radioligand Assay	Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).	Protein-Binding Radioassay,Radioreceptor Assay,Assay, Radioligand,Assay, Radioreceptor,Assays, Radioligand,Assays, Radioreceptor,Protein Binding Radioassay,Protein-Binding Radioassays,Radioassay, Protein-Binding,Radioassays, Protein-Binding,Radioligand Assays,Radioreceptor Assays
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D004372	Ducks	A water bird in the order Anseriformes (subfamily Anatinae (true ducks)) with a broad blunt bill, short legs, webbed feet, and a waddling gait.	Duck
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001345	Autoradiography	The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)	Radioautography