title: The role of glutathion conjugation in the regulation of early toad embryos' tolerance to pesticides.
abstract: Reduced glutathion (GSH) content and glutathione S-transferase (GSH S-transferase) activity were investigated in developing toad embryos exposed to parathion, malathion, lindane and dieldrin. The embryonic GSH content was reduced after 96 h of incubation with 20.00 ppm malathion and 2.00 ppm lindane. Parathion and dieldrin did not produce any change. A similar effect was obtained in advanced stages of development (6-days larvae), but only with malathion. No correlation between the decrease in GSH level and mortality or morphologic abnormalities was observed. The four pesticides increased the activity of GSH S-transferase indicating that the enzyme is susceptible to induction during early development. The higher effect depicted by malathion may be related with an enhanced conjugation of the pesticide. Both GSH decrease and GSHS-transferase induction modifies the cell redox status and may indirectly influence transcription and translation. The early expression of GST genes provides the embryo with a useful mechanism for the regulation of tolerance against chemical stress.
authors.affiliation: LIBIQUIMA, Department of Chemistry, National University of Comahue, Buenos Aires 1400, 8300 Neuquen, Argentina.
authors.forename: O L
authors.initials: OL
authors.lastname: Anguiano
authors.forename: A
authors.initials: A
authors.lastname: Caballero de Castro
authors.forename: A M
authors.initials: AM
authors.lastname: Pechen de D'Angelo
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects; D002022:Bufo arenarum / Q000196:embryology / Q000502:physiology*; D004026:Dieldrin / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000502:physiology*; D004790:Enzyme Induction / Q000187:drug effects; D005775:Gastrula / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism*; D001556:Hexachlorocyclohexane / Q000633:toxicity; D007814:Larva; D008294:Malathion / Q000633:toxicity; D010278:Parathion / Q000633:toxicity; D010575:Pesticides / Q000633:toxicity*; D012880:Skin Pigmentation / Q000187:drug effects
chemical_list: D010575:Pesticides; D001556:Hexachlorocyclohexane; D010278:Parathion; D005982:Glutathione Transferase; D005978:Glutathione; D004026:Dieldrin; D008294:Malathion