Transcriptional landscape of Saccharomyces cerevisiae exposed to different concentrations of commercial graphene nanoplatelets

Graphene nanomaterials have attracted a great interest during the last years in different research areas due to their unique electronic, mechanical, thermal and optical properties. In this work, we carried out a toxicity assessment to understand the toxicity of commercial graphene nanoplatelets (GN) on the unicellular eukaryotic organism Saccharomyces cerevisiae. This fungus is one of the most widely used eukaryotic models to understand basic molecular processes in higher eukaryotes, and is increasingly used in toxicity assessment of chemicals and nanomaterials. The obtained results showed that cell proliferation was not negatively affected even in the presence of 800 mg L-1 of the nanomaterial during 24 hours, but oxidative stress was induced by a lower concentration (160 mg L-1) after short exposure periods (2 and 4 hours). The genotoxic potential of GN was evaluated through the comet assay, and no DNA damage was observed under the studied conditions. Additionally, to pinpoint the molecular mechanisms behind the early oxidative damage induced by GN, and to identify possible toxicity pathways, the transcriptional response of S. cerevisiae to 160 and 800 mg L-1 of GN was studied. Both GN concentrations induced expression changes in a common group of genes (327), many of them related to the fungal response to reduce the nanoparticles toxicity and to maintain cell homeostasis. In addition, a high number of genes were only differentially expressed in the GN800 condition (3193), indicating that high GN concentrations are able to induce severe changes in the physiological state of the yeast.