Abstract
Increasing utilization of stabilized iron sulfides (FeS) nanoparticles implies an elevated release of the materials into the environment. To understand potential impacts and underlying mechanisms of nanoparticle-induced stress, we used the transcriptome sequencing (RNA-seq) technique to characterize the transcriptomes from adult zebrafish exposed to 10 mg/L carboxymethyl cellulose (CMC) stabilized FeS nanoparticles for 96 h, demonstrating striking differences in the gene expression profiles in liver. The exposure caused significant expression alterations in genes related to immune and inflammatory responses, detoxification, oxidative stress and DNA damage/repair. The complement and coagulation cascades Kyoto encyclopedia of genes and genomes (KEGG) pathway was found significantly up-regulated under nanoparticle exposure. The quantitative real-time polymerase chain reaction using twelve genes confirmed the RNA-seq results. We identified several candidate genes commonly regulated in liver, which may serve as gene indicators when exposed to the nanoparticles. Hepatic inflammation was further confirmed by histological observation of pyknotic nuclei, and vacuole formation upon exposure. Tissue accumulation tests showed a 2.2 times higher iron concentration in the fish tissue upon exposure. This study provides preliminary mechanistic insights into potential toxic effects of organic matter stabilized FeS nanoparticles, which will improve our understanding of the genotoxicity caused by stabilized nanoparticles.
Highlights
To facilitate in situ remediation of contaminated soil and groundwater, stabilized NPs are often employed
At the dosage of 10 mg/L as Fe, the dissolved Fe concentration of carboxymethyl cellulose (CMC)-FeS was 0.20 mg/L, indicating that the nanoparticles remained essentially undissolved throughout the exposure period
The findings were further supported by histological evidence, which may be used as a reference for phenotype-anchoring points for certain classes of genes in future studies
Summary
To facilitate in situ remediation of contaminated soil and groundwater, stabilized NPs are often employed. Compared to the non-stabilized counterparts, stabilized NPs are often much smaller in size, more mobile in the environment, and more reactive[17]. The recently developed transcriptome sequencing (RNA-seq) technique provides a powerful tool for investigating into the genotoxic effects and the molecular mechanisms in organisms after a chemical exposure. It is useful for studying emerging environmental pollutants with limited toxicological information, such as NPs, since it allows for a global examination of biological response through gene expression. Zebrafish (Danio rerio), whose genome has been completely sequenced, is a common model organism for investigating genotoxic effects of chemicals, and it has been used in studying the eco-toxicological effects of engineered NPs25,26
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