Phenomic and Transcriptomic Profiling of ZnS QD Response in Saccharomyces cerevisiae: A Quantum Model Organism for a...

Quantum dots such as CdS QDs have been extensively studied using human cells, plants, and unicellular eukaryotes such as Saccharomyces cerevisiae, whereas ZnS QDs-considered low-toxicity alternatives to cadmium-based nanomaterials-remain comparatively underexplored. Following preliminary analyses of ZnS QDs' effects on wild-type S. cerevisiae BY4742 growth, the Yeast Knock-Out collection, comprising ~4600 haploid mutants deleted in non-essential genes, was screened in the presence of ZnS QDs. Sensitive mutants were predominantly associated with mitochondrial functions, prompting further characterization of sod1Δ, glr1Δ, and of the hypersensitive mutant pos5Δ. This last mutant, which lacks a mitochondrial NADH kinase, showed hypersensitivity specific to ZnS QDs but not to CdS QDs or zinc sulfate (ZnSO₄). Flow cytometry analysis of the wild-type strain and the pos5Δ mutant detected no significant increase in reactive oxygen species after ZnS QD treatment. RNA-sequencing analyses of the wild-type strain and the pos5Δ mutant exposed to ZnS QDs (or ZnSO₄) revealed that ZnS QD exposure selectively modulated genes encoding mitochondrial proteins, metal-binding factors, and intracellular trafficking components. Comparison with published data on CdS QDs identified specific mechanisms involving protein synthesis and degradation. Saccharomyces cerevisiae once again proved its versatility for studying engineered nanomaterial interactions with biological systems.