RNA-Seq analysis of the effects of metal nanoparticle exposure on the transcriptome of Chlamydomonas reinhardtii

The wide spread use of anoparticles (NPs) raises concern of their potential toxicological effects in humans and ecosystems. Here researchers at the Université de Montréal used RNA-Seq to evaluate the effects of exposure to four different metal-based NPs, nAg, nTiO2, and nZnO and CdTe/CdS quantum dots (QD), in the eukaryotic green alga Chlamydomonas reinhardtii. The transcriptome was characterized before and after exposure to each NP type. Specific toxicological effects were inferred from the functions of genes whose transcripts either increased or decreased. Data analysis resulted in important differences and also similarities among the NPs. Elevated levels of transcripts of several marker genes for stress were observed, suggesting that only nZnO caused non-specific global stress to the cells under environmentally relevant conditions. Genes with photosynthesis-related functions were decreased drastically during exposure to nTiO2 and slightly during exposures to the other NP types. This pattern suggests either toxicological effects in the chloroplast or effects that mimic a transition from low to high light. nAg exposure dramatically elevated the levels of transcripts encoding known or predicted components of the cell wall and the flagella, suggesting it damages structures exposed to the external milieu. Exposures to nTiO2, nZnO, and QD elevated transcripts encoding subunits of the proteasome, suggesting proteasome inhibition, a phenomenon believed to underlie the development and progression of several major diseases, including Alzheimer’s disease, and used in chemotherapy against multiple myeloma.

rna-seq

  • Simon DF, Domingos RF, Hauser C, Hutchins CM, Zerges W, Wilkinson KJ. (2013) RNA-Seq analysis of the effects of metal nanoparticle exposure on the transcriptome of Chlamydomonas reinhardtii. Appl Environ Microbiol [Epub ahead of print]. [abstract]