Citrate gold nanoparticle exposure in the marine clam Ruditapes philippinarum: Uptake, elimination and effect

Trabajo presentado en la SETAC Europe 24th Annual Meeting (Science Across Bridges, Borders and Boundaries), celebrada en Basilea del 11 al 15 de mayo de 2014.Engineered gold nanoparticles (AuNPs) are introduced into a growing number of commercial products. The resulting increase in likelihood of release into various environmental compartments needs to be met by an increased understanding of their effects on the species within. Up to date limited information is available on the ecotoxicological risk for non-target organisms in marine environments, with the majority of research focusing on m agnified expectable environmental concentrations. In our laboratory-based study the bivalve Ruditapes philippinarumwas chosen as a model to evaluate uptake, elimination and sub-cellular effects of citrate -stabilized AuNPs (21.5 ± 2.9 nm) at an environmental relevant concentration (0.75 μg L-1) over 14 days. Tissue (digestive gland and gills) was sampled on days 0,1, 7 and 14 to record changes in the expression of chosen endpoints over time. Gold concentration in tissue and faeces, enzymatic biomarkers of i.) oxidative stress (CAT, GST, SOD, GPx, GPx-Se), ii.) damage (lipid peroxidation, DNA strand breaks) and iii.) exposure (Metallothionein, AChE), as well as gene expression by means of quantitative reverse transcription PCR (qRT-PCR) for selected sets of genes were measured. We observed an uptake of AuNPs in both organs and an effect on the activity of the tested biomarkers, with the digestive gland being the primary target organ. While qRT-PCR expression levels raise some concerns regarding the effects of chronic AuNP exposure, at the tested concentration the particles did not cause significant oxidative damage. Further we could demonstrate a significant elimination of Au from the digestive track within a 7 day purification period, with excretion being an important pathway.N