title: Response of biochemical biomarkers in the aquatic crustacean Daphnia magna exposed to silver nanoparticles.
abstract: The proliferation of silver nanoparticle (AgNP) production and use owing to their antimicrobial properties justifies the need to examine the resulting environmental impacts. The discharge of biocidal nanoparticles to water bodies may pose a threat to aquatic species. This study evaluated the effects of citrate-coated AgNPs on the standardized test organism Daphnia magna Straus clone MBP996 by means of biochemical biomarker response. AgNP toxicity was compared against the toxic effect of Ag(+). The toxicity endpoints were calculated based upon measured Ag concentrations in exposure media. For AgNPs, the NOAEC and LOAEC values at 48 h were 5 and 7 μg Ag/L, respectively, while these values were 0.5 and 1 μg Ag/L, respectively, for Ag(+). The EC50 at 48 h was computed to be 12.4 ± 0.6 and 2.6 ± 0.1 μg Ag/L for AgNPs and Ag(+), respectively, with 95 % confidence intervals of 12.1-12.8 and 2.3-2.8 μg Ag/L, respectively. These results indicate significant less toxicity of AgNP compared to free Ag(+) ions. Five biomarkers were evaluated in Daphnia magna neonates after acute exposure to Ag(+) or AgNPs, including glutathione (GSH) level, reactive oxygen species (ROS) content, and catalase (CAT), acetylcholinesterase (AChE), and superoxide dismutase (SOD) activity. AgNPs induced toxicity and oxidative stress responses in D. magna neonates at tenfold higher concentrations than Ag. Biochemical methods revealed a clear increase in AChE activity, decreased ROS level, increased GSH level and CAT activity, but no significant changes in SOD activity. As Ag(+) may dissolve from AgNPs, these two types of Ag could act synergistically and produce a greater toxic response. The observed remarkably high toxicity of AgNPs (in the parts-per-billion range) to crustaceans indicates that these organisms are a vulnerable link in the aquatic food chain with regard to contamination by nanosilver. Graphical Abstract ᅟ.
authors: Andrija Štampar Teaching Institute of Public Health, Mirogojska 16, 10 000, Zagreb, Croatia.
authors: Lea
authors: L
authors: Ulm
authors: Andrija Štampar Teaching Institute of Public Health, Mirogojska 16, 10 000, Zagreb, Croatia.
authors: Adela
authors: A
authors: Krivohlavek
authors: Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia.
authors: Darija
authors: D
authors: Jurašin
authors: Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10 000, Zagreb, Croatia.
authors: Marija
authors: M
authors: Ljubojević
authors: Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10 000, Zagreb, Croatia.
authors: Goran
authors: G
authors: Šinko
authors: Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovačića 1, 10 000, Zagreb, Croatia.
authors: Tea
authors: T
authors: Crnković
authors: Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovačića 1, 10 000, Zagreb, Croatia.
authors: Irena
authors: I
authors: Žuntar
authors: Andrija Štampar Teaching Institute of Public Health, Mirogojska 16, 10 000, Zagreb, Croatia.
authors: Sandra
authors: S
authors: Šikić
authors: Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10 000, Zagreb, Croatia. ivinkovic@imi.hr.
authors: Ivana
authors: I
authors: Vinković Vrček
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D019343:Citric Acid / Q000737:chemistry; D003621:Daphnia / Q000187:drug effects* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D019055:No-Observed-Adverse-Effect Level; D017382:Reactive Oxygen Species / Q000378:metabolism; D012834:Silver / Q000737:chemistry / Q000633:toxicity*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D015415:Biomarkers; D017382:Reactive Oxygen Species; D019343:Citric Acid; D012834:Silver; D002374:Catalase; D013482:Superoxide Dismutase; D000110:Acetylcholinesterase; D005978:Glutathione
keywords: Biomarkers; Daphnia magna; Oxidative stress; Silver nanoparticles; Toxicity