Cadmium-induced oxidative stress and transcriptome changes in the wolf spider Pirata subpiraticus

Spiders are believed to have enormous potential for indicating heavy metal pollution in ecosystems. The diversity of influencing factors caused significant differences in the toxicities of cadmium (Cd) on spiders. There is limited understanding of the underlying mechanism and response to acute Cd exposure at different concentrations and different poisoning times. We exposed adult female P. subpiraticus to 0.2 mM and 2 mM Cd for 6 and 12 h, respectively, to explore acute Cd toxicities by RNA-seq. We measured the bioaccumulation levels in P. subpiraticus and tested the activities of superoxide dismutase (SOD) and glutathione S-transferase (GST). There were 187, 292, 101 and 155 differentially expressed genes (DEGs) after exposure to 0.2 mM and 2 mM Cd for 6 and 12 h, respectively. The results revealed that Cd accumulated in P. subpiraticus, changed the SOD and GST activities, and caused significant adverse effects at the molecular level on metabolism and immune and oxidative stress, with time- and concentration-dependent differences. Transcriptome analysis showed that acute Cd exposure depressed lipid metabolism and induced protein metabolism, especially serine metabolism. Genes encoding lipoproteins were depressed when exposed to 0.2 mM Cd, while fatty acid-related genes were downregulated under 2 mM Cd stress. In total, 46 cuticle-related genes were upregulated, and 6 cytoskeleton-related genes changed notably in the immune process. Peroxidase-related genes were further upregulated significantly. Meanwhile, the pathways related to metabolism, immunity and oxidative stress were significantly enriched. This report illustrated that acute Cd exposure exerts toxicities on P. subpiraticus and the spiders against acute Cd toxicities by selective differential expression of the genes associated with the physiological process of metabolism and immune and antioxidant stress. This study provides a comprehensive transcriptional basis for understanding the response of the P. sublimations to heavy metals at different concentrations and different treatment times.