title: Differential sensitivity in embryonic stages of the zebrafish (Danio rerio): The role of toxicokinetics for stage-specific susceptibility for azinphos-methyl lethal effects.
abstract: The occasionally observed differential chemical sensitivity in embryonic life stages of fish is still poorly understood and could represent an important issue for understanding the time course of toxicity and the toxic modes of action of chemicals. In this study we analyzed the toxicity of the acetylcholinesterase inhibitor azinphos-methyl (APM) in different life-stages of zebrafish embryos. To this end, the LC50 of three 48h-exposure windows were determined (12μM for 0-48, no mortality observed for 24-72 and 72-120hpf up to a concentration of 79μM). We hypothesized that the differential sensitivity of the stage-specific embryos may be related to differences in uptake of the compound and/or internal concentrations. Therefore, internal concentrations were determined using HPLC. Similar levels and time courses of internal concentrations for all three exposure windows were observed. Bioconcentration amounted to a factor of about 30. Short-term exposure windows for a concentration 4-fold above the calculated LC50 (47μM) identified the period of 0-4hpf as the most sensitive time window for APM toxicity. Our results indicate that the differential sensitivity of APM in the embryos is not related to differences in internal concentrations but related to a stage specific mechanisms of toxicity.
authors.affiliation: UFZ - Helmholtz Centre for Environmental Research, Department Bioanalytical Ecotoxicology, Permoserstr. 15, 04318 Leipzig, Germany. Electronic address: riccardo.massei@ufz.de.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Massei
authors.affiliation: UFZ - Helmholtz Centre for Environmental Research, Department Bioanalytical Ecotoxicology, Permoserstr. 15, 04318 Leipzig, Germany.
authors.forename: Carolina
authors.initials: C
authors.lastname: Vogs
authors.affiliation: UFZ - Helmholtz Centre for Environmental Research, Department Bioanalytical Ecotoxicology, Permoserstr. 15, 04318 Leipzig, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Renner
authors.affiliation: UFZ - Helmholtz Centre for Environmental Research, Department Bioanalytical Ecotoxicology, Permoserstr. 15, 04318 Leipzig, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Altenburger
authors.affiliation: UFZ - Helmholtz Centre for Environmental Research, Department Bioanalytical Ecotoxicology, Permoserstr. 15, 04318 Leipzig, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Scholz
mesh_terms: D000818:Animals; D001387:Azinphosmethyl / Q000633:toxicity*; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D066007:Toxicokinetics; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000196:embryology*
chemical_list: D014874:Water Pollutants, Chemical; D001387:Azinphosmethyl
keywords: Azinphos-methyl; Risk assessment; Sensitivity windows; Toxicodynamics; Toxicokinetics; Zebrafish