Transcriptomics-Based Toxicological Study of Nickel on Caenorhabditis elegans

Nickel (Ni), a heavy metal with extensive industrial applications, poses significant ecological impacts and health risks due to its persistence and bioaccumulation. Although toxicological data in mammals and plants are well established, its effects on invertebrate models remain insufficiently explored, especially at environmentally relevant concentrations. This study systematically evaluated the toxicity of Ni²⁺ on Caenorhabditis elegans, integrating phenotypic assays with transcriptomic profiling to assess impacts on growth, reproduction, neuromuscular function, lifespan, and aging. Ni exposure induced dose-dependent developmental delays. After exposure to 80 μg/L Ni²⁺ for 72 h, the proportion of L1-stage nematodes increased 3.8-fold compared to the control group. Similarly, exposure to 80 µg/L Ni²⁺ reduced the reproductive capacity of nematodes to 88.5% of that in the control group. Transcriptomic analysis identified 2235 differentially expressed genes (DEGs) after 8 μg/L of Ni²⁺ exposure, while the worms exposed to 0.8 μg/L of Ni²⁺ exhibited a total of 249 DEGs. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses highlighted collagen metabolism defects, fatty acid-related metabolism, amino acid-related biosynthesis disruption, and lysosomal dysfunction, correlating with cuticle integrity loss, energy metabolism abnormality, and feeding behavior change, and indirectly lead to delayed growth development and lipofuscin accumulation. The latter is usually regarded as a reliable indicator of aging, suggesting that exposure to Ni poses a risk of accelerating aging in nematodes. This study provides critical insights into the ecological risks of Ni pollution.