Is gene transcription in mussel gills altered after exposure to Ag nanoparticles?

Abstract

Nanotechnology is a rapid field of development with the enhancement of the production of different types of nanoparticles (NPs) applied in several industrial and commercial applications which increase the risk of their presence in the aquatic environment. Ag NPs have a wide application in everyday life products. However, there is concern about the exposure effects on aquatic organisms to these NPs. Therefore, this study aims to assess gene transcription alterations in mussels Mytilus galloprovincialis gills exposed for 2 weeks to Ag NPs (42 ± 10 nm, 10 μg.L(-1)). The genes were selected based on previous biomarkers and proteomic results and included superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST), caspase 3/7-1 (CAS), cathepsin L (CATH), heat-shock protein 70 (HSP 70), cytochrome P450 4YA (CYP 4YA), the elongation factor (EF1), actin and α- tubulin. No significant changes in gene transcription profiles were observed after exposure of M. galloprovincialis to Ag NPs for 15 days. The lack of significant gene transcription responses is in light with previous results obtained for mussels exposed to these NPs and may be related to the fact that enzyme kinetics and relative abundance of proteins (increase of antioxidant enzymes and metalllothioneins (MTs) with the time of exposure) do not always directly reflect their relative mRNA levels. Nevertheless, their overall expression maintenance may signify that, at end of the exposure period (15 days), the transcription of the respective genes is no longer required, pointing out to a possible adaptation effect to nanoparticles or due to the levels of Ag NPs accumulated in this tissue at this exposure time. This study highlights that gene transcription application and role as an additional and/or alternative end point approach is important to understand the mode of action of these emergent contaminants in aquatic organisms. However, in future studies, the time window needs to be adjusted, as genes are likely to respond earlier to the nanoparticle exposure.

Effects of nanomaterials on marine invertebrates

“…Although the gills of C. gigas and M. galloprovincialis are susceptible to oxidative stress induced by ZnO and CuO NPs, this was not the case with other metal-based NPs (reviewed in Rocha et al, 2015). Gene transcription profiles were not significantly altered in the gills of M. galloprovincialis exposed to Ag NPs after 15 days, although changes in expression may occur at shorter times of exposure (Bebianno et al, 2015).…”

Building the Bridge From Aquatic Nanotoxicology to Safety by Design Silver Nanoparticles

“…Cytotoxicity on mussel's hemocytes exposed in vitro for 24 h was also observed (Duroudier et al, 2019b). Changes in mussel's gill and digestive gland proteome, but not in gene transcription profile, were previously reported upon exposure to either AgNPs (10 µgL −1 AgNPs for 15 days) or AgNO3, but with different expression signatures, thus suggesting the involvement of different mechanisms in the observed AgNP and Ag ion toxicity (Gomes et al, 2013a, Gomes et al, 2013bBebianno et al, 2015). In a similar study, the same authors showed Ag accumulation in both tissues (gills and digestive glands) and induction of antioxidant enzymes and metollotionein; however, in the digestive glands, only a small fraction of Ag seems to be associated with this protein as well as for lipid peroxidation more marked in the gills than in the digestive glands (Gomes et al, 2014).…”

“…Several contributions have investigated the ecotoxicity of AgNPs in marine benthic filter-feeders as bivalves, as they are recognized among the most suitable marine bioindicators of anthropogenic pollutants including the emerging ENM/Ps ( Matranga and Corsi, 2012 ; Canesi and Corsi, 2016 ). In vivo studies mostly concentrated on the understanding of potential bioaccumulation through waterborne exposure and biological effects through physiological and molecular biomarkers in potential target tissues (e.g., gills, immune circulating cells as hemocytes, and digestive glands) ( Ringwood et al, 2010 ; Buffet et al, 2013 ; Gomes et al, 2013a , Gomes et al, 2013b ; McCarthy et al, 2013 , Gomes et al, 2014 ; Buffet et al, 2014 ; Bebianno et al, 2015 ; Katsumiti et al, 2015 ; Jimeno-Romero et al, 2017 ). Omics studies have also been performed to unravel the mechanism of actions and pathways of exposure by transcriptomics and proteomics coupled with physiological responses.…”

Changes of Gene Expression Patterns from Aquatic Organisms Exposed to Metal Nanoparticles

“…After 28 days of exposure to 1 µg L −1 and 25 µg L −1 silver nanoparticles, the liver of male medaka (Oryzias latipes) showed increased expression of S-glutathione transferase gene for 1 µg L −1 concentration and Hsp70, choriogenin, and vitellogenin genes for 25 µg L −1 concentration, whereas both concentrations of silver NPs induced higher expression of transferrin than in the control group [31]. After mussels Mytilus galloprovincialis had been incubated for two weeks in water containing 10 µg L −1 AgNPs, it was found that CYP4YI (cytochrome) and cathepsin (protease) genes showed increased tran-script levels, whereas GST and caspase genes (protease involved in apoptosis) exhibited down-regulation [32].…”