Proteomic Analysis of Heavy Metal-Induced Toxicity Using the Cellular Slime Mould Dictyostelium discoideum: Effects of Copper Exposure on Aggregation and Protein Expression

The cellular slime mold Dictyostelium discoideum is a soil-dwelling eukaryotic organism that undergoes distinctive morphological changes during starvation, making it a promising candidate for bioassay development. In this study, we evaluated the impact of copper exposure on the morphological transformation of D. discoideum and performed a comparative proteomic analysis. Copper exposure on agar media delayed aggregate formation by 3.5 hours compared to controls. Using immobilized pH gradient two-dimensional gel electrophoresis followed by silver staining, approximately 280 protein spots were detected. Three spots were found to disappear upon copper exposure. Based on isoelectric point and molecular weight analyses, the proteins were predicted to be formin-1, cytoplasmic regulator of adenylyl cyclase (CRAC), and a tetratricopeptide repeat (TPR)-containing protein. Formin-1 and CRAC are known to be involved in aggregation processes. These findings suggest copper disrupts aggregation-related protein expression in D. discoideum　and highlight the potential of D. discoideum-based bioassays using proteomic biomarkers for environmental monitoring.