Revealing Single-Cell Heterogeneity of Labile Cu(I) Accumulation and Metabolism in Microalgae by Image-Enabled Flow...

Area of Science:

• Environmental toxicology
• Cellular biology
• Microalgal research

Background:

• Single-cell heterogeneity in metal uptake and toxicity is poorly understood.
• Living organisms exhibit intrinsic heterogeneity, but its role in metal metabolism is unclear.

Purpose of the Study:

• Investigate single-cell heterogeneity of labile copper(I) [Cu(I)] metabolism in *Chlamydomonas reinhardtii*.
• Understand differential cellular sensitivity and labile Cu(I) accumulation under chronic copper stress.

Main Methods:

• Utilized an image-enabled flow cytometer platform for single-cell analysis.
• Performed multiomics analyses and confocal imaging.
• Applied Gene Set Enrichment Analysis (GSEA).

Main Results:

• Identified two subpopulations: low Cu(I) (LCu(I)) and high Cu(I) (HCu(I)) cells, with distinct labile Cu(I) bioaccumulation.
• Observed a shift from LCu(I) to HCu(I) cells under increased Cu stress.
• Identified Ctr3p as a potential regulator of Cu(I) homeostasis and aberrant glutathione (GSH) compartmentalization in HCu(I) cells.

Conclusions:

• Single-cell heterogeneity in labile Cu(I) metabolism is evident in microalgae.
• Hyperaccumulated Cu(I) in HCu(I) cells leads to cytotoxicity and photosynthesis inhibition.
• Accounting for subpopulation-specific responses is crucial for accurate metal toxicity assessments.