Commonalities and Differences in the Transcriptional Response of the Model Fungus Saccharomyces cerevisiae to Different Commercial Graphene Oxide Materials

Abstract

Graphene oxide has become a very appealing nanomaterial during the last years for many different applications, but its possible impact in different biological systems remains unclear. Here, an assessment to understand the toxicity of different commercial graphene oxide nanomaterials on the unicellular fungal model organism Saccharomyces cerevisiae was performed. For this task, an RNA purification protocol was optimized to avoid the high nucleic acid absorption capacity of graphene oxide. The developed protocol is based on a sorbitol gradient separation process for the isolation of adequate ribonucleic acid levels (in concentration and purity) from yeast cultures exposed to the carbon derived nanomaterial. To pinpoint potential toxicity mechanisms and pathways, the transcriptome of S. cerevisiae exposed to 160 mg L −1 of monolayer graphene oxide (GO) and graphene oxide nanocolloids (GOC) was studied and compared. Both graphene oxide products induced expression changes in a common group of genes (104), many of them related to iron homeostasis, starvation and stress response, amino acid metabolism and formate catabolism. Also, a high number of genes were only differentially expressed in either GO (236) or GOC (1077) exposures, indicating that different commercial products can induce specific changes in the physiological state of the fungus.

Low Toxicological Impact of Commercial Pristine Multi-Walled Carbon Nanotubes on the Yeast Saccharomyces cerevisiae

“…Colony forming units (CFUs) determination, a standard population quantification method, allowed to measure the potential viability reduction of yeast cells in the presence of NTX1 nanotubes. The exposure conditions were chosen based on those employed in previous research works, allowing a direct comparison of the obtained results with recent studies, were the unicellular fungus was exposed to nanomaterials from different families, such as graphene derivatives, 2D transition metal dichalcogenides (TMDs), or 2D boron nitride [ 19 , 22 , 39 , 40 , 41 , 42 ]. As displayed in Figure 3 , after two hours, CFUs of S. cerevisiae exposed to both concentrations were similar to those shown by non-exposed cells.…”

“…FRE1 produces a cell-surface iron reductase whose overexpression is induced during iron and copper depletion and causes copper sensitivity. Interestingly, the overexpression of iron homeostasis genes in yeast has been reported several times upon exposure to carbon based nanoparticles, such as graphene nanoplatelets and graphene oxide [ 19 , 41 , 49 ], which have been associated to iron scarcity due to the chelating properties of the nanomaterials. In addition, IRC7, which codes for a cysteine desulphydrase, enabling growth on cysteine as a nitrogen source, is induced in nitrogen and copper limiting conditions [ 50 ], while the high-affinity glucose transporter HXT4 has been shown to be overexpressed in low levels of glucose [ 51 ].…”

“…In addition, IRC7, which codes for a cysteine desulphydrase, enabling growth on cysteine as a nitrogen source, is induced in nitrogen and copper limiting conditions [ 50 ], while the high-affinity glucose transporter HXT4 has been shown to be overexpressed in low levels of glucose [ 51 ]. As discussed in previous studies where transcriptional changes in genes associated with low nutrient availability were observed when S. cerevisiae cells were exposed to graphene nanomaterials, their capacity to adsorb biomolecules and ions could lower their availability for biological systems [ 41 ].…”

“…Analysis of RNA sequencing data was done following the protocol previously presented [ 41 ]. Briefly, read pre-processing for quality filtering was done using FastqPuri [ 59 ].…”

Graphene Oxide Exhibits Antifungal Activity against Bipolaris sorokiniana In Vitro and In Vivo

“…Most reports have investigated the antimicrobial effects of graphene in vitro [ 12 , 32 , 54 , 56 , 57 ]. To our knowledge, pathogen pathogenicity experiments on graphene’s antimicrobial effect in vivo have only been performed for Fusarium Head Blight and Plasmopara viticola [ 19 , 27 ].…”