title: Uptake, metabolism, and effects on detoxication enzymes of isoproturon in spawn and tadpoles of amphibians.
abstract: Using ring-(14)C-labeled isoproturon (1 microg/L), the uptake into spawn and tadpoles of Bombina bombina and Bombina variegata was investigated. Two percent of the applied radioactivity was found per gram fresh weight in the embryo after 24h. Results indicate that the jelly mass of the spawn does not act as a sufficient physical barrier for protection against the uptake and influence of isoproturon (IPU) on the embryo. In vivo metabolism of ring-14C-labeled IPU by the cytochrome P-450 system was analyzed in tadpoles. Different metabolites of IPU, such as N-demethylated and C-hydroxylated derivatives, and the olefinic metabolite were detected. In tadpoles of B. variegata, the activity of microsomal and soluble glutathione-S-transferase (sGSTs) toward different model substrates was measured after treatment with IPU. Activities of sGST increased corresponding to elevated stress by IPU dependent on exposure time and dose. Compared to the pure active ingredient IPU, the commercial phenyl-urea herbicide Tolkan Flo, consisting of IPU and an emulsifier, also caused significantly elevated enzymatic response.
authors.affiliation: Institute of Freshwater Ecology and Inland Fisheries, 12587, Berlin, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Greulich
authors.forename: Enamul
authors.initials: E
authors.lastname: Hoque
authors.forename: Stephan
authors.initials: S
authors.lastname: Pflugmacher
mesh_terms: D000818:Animals; D001001:Anura / Q000502:physiology*; D002250:Carbon Radioisotopes; D004305:Dose-Response Relationship, Drug; D005982:Glutathione Transferase / Q000494:pharmacology*; D006540:Herbicides / Q000009:adverse effects / Q000378:metabolism / Q000493:pharmacokinetics*; D007700:Kinetics; D007814:Larva / Q000502:physiology; D008782:Methylurea Compounds / Q000009:adverse effects / Q000378:metabolism / Q000493:pharmacokinetics*; D008861:Microsomes; D010671:Phenylurea Compounds; D014018:Tissue Distribution
chemical_list: D002250:Carbon Radioisotopes; D006540:Herbicides; D008782:Methylurea Compounds; D010671:Phenylurea Compounds; C028904:isoproturon; D005982:Glutathione Transferase