title: Metallothionein modulation in relation to cadmium bioaccumulation and age-dependent sensitivity of Chironomus riparius larvae.
abstract: The goal of this study was to contribute to understanding of the mechanisms behind sensitivity differences between early and late instar larvae of Chironomus riparius and to address the influence of the differences in standard testing approaches on the toxicity evaluation. A 10-day contact sediment toxicity test was carried out to assess sensitivity to cadmium exposure in relation to different age and laboratory culture line origin of test organisms. Chironomid larvae of early (OECD 218 method) and late instar (US-EPA600/R-99/064 method) differed substantially in sensitivity of traditional endpoints (OECD: LOEC 50 and 10 μg Cd/g dry weight (dw); US-EPA: LOEC > 1000 and 100 μg Cd/g dw for survival and growth, respectively). Bioaccumulated cadmium and metallothioneins (MTs) concentrations were analyzed to investigate the role of MTs in reduced sensitivity to cadmium in late instar larvae. Metallothioneins were induced after treatment to greater Cd concentrations, but their levels in relation to cadmium body burdens did not fully explain low sensitivity of late instars to cadmium, which indicates some other effective way of detoxification in late instars. This study brings new information related to the role of MTs in age-dependent toxicant sensitivity and discusses the implications of divergence in data generated by chironomid sediment toxicity tests by standardized methods using different instars.
authors.affiliation: Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Toušová
authors.affiliation: Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Kuta
authors.affiliation: Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00, Brno, Czech Republic.
authors.forename: David
authors.initials: D
authors.lastname: Hynek
authors.affiliation: Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00, Brno, Czech Republic.
authors.forename: Vojtěch
authors.initials: V
authors.lastname: Adam
authors.affiliation: Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00, Brno, Czech Republic.
authors.forename: René
authors.initials: R
authors.lastname: Kizek
authors.affiliation: Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
authors.forename: Luděk
authors.initials: L
authors.lastname: Bláha
authors.affiliation: Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic. hilscherova@recetox.muni.cz.
authors.forename: Klára
authors.initials: K
authors.lastname: Hilscherová
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D002683:Chironomidae / Q000187:drug effects*; D004781:Environmental Exposure; D007814:Larva / Q000187:drug effects; D008668:Metallothionein / Q000032:analysis / Q000378:metabolism*; D018675:Toxicity Tests
chemical_list: D002104:Cadmium; D008668:Metallothionein
keywords: Artificial sediment; Bioaccumulation; Cadmium; Chironomus; Metallothionein