Saccharomyces cerevisiae exposure to Multi-Walled Carbon Nanotubes for 2h at 160 mg/L (CN160) and 800 mg/L (CN800)

Carbon nanotubes (CNTs) have attracted the attention of academy and industry due to their potential applications, being currently produced and commercialized at mass scale, but their possible impact on different biological systems remains unclear. In the present work, an assessment to understand the toxicity of commercial MWCNTs (NTX1, provided by the company Nanothinx) on the unicellular fungal model Saccharomyces cerevisiae was performed. Firstly, the nanomaterial was physico-chemically characterized, to obtain insights about its morphological features and trace elements composition. Afterwards, a toxicology assessment was done, where it could be observed that cell proliferation was negatively affected in the presence of 800 mg L-1 of the nanomaterial for 24 hours, while oxidative stress was induced at a lower concentration (160 mg L-1) after short exposure periods (2 and 4 hours). Finally, to pinpoint molecular mechanisms behind the early damage induced by NTX1 CNTs and to identify possible toxicity pathways, the transcriptome of S. cerevisiae exposed to 160 and 800 mg L-1 of the selected nanomaterial was studied. Surprisingly, only a small number of genes showed significant transcriptional changes in the presence of the higher concentration employed (130), most of them found downregulated, indicating a limited biological response of the yeast cells exposed to NTX1. Nevertheless, many of the genes with expression levels changes in the presence of MWCNTs were involved in molecular mechanisms previously described to be altered in the presence of other toxicants and carbon derived nanomaterials, with functions related metal ion homeostasis, nutrients utilization, stress response, RNA metabolic processes and ribosome biogenesis.