Transcriptome Profiling Analysis of Wolf Spider Pardosa pseudoannulata (Araneae: Lycosidae) after Cadmium Exposure.

Pardosa pseudoannulata is one of the most common wandering spiders in agricultural fields and a potentially good bioindicator for heavy metal contamination. However, little is known about the mechanisms by which spiders respond to heavy metals at the molecular level. In the present study, high-throughput transcriptome sequencing was employed to characterize the de novo transcriptome of the spiders and to identify differentially expressed genes (DEGs) after cadmium exposure. We obtained 60,489 assembled unigenes, 18,773 of which were annotated in the public databases. A total of 2939 and 2491 DEGs were detected between the libraries of two Cd-treated groups and the control. Functional enrichment analysis revealed that metabolism processes and digestive system function were predominately enriched in response to Cd stress. At the cellular and molecular levels, significantly enriched pathways in lysosomes and phagosomes as well as replication, recombination and repair demonstrated that oxidative damage resulted from Cd exposure. Based on the selected DEGs, certain critical genes involved in defence and detoxification were analysed. These results may elucidate the molecular mechanisms underlying spiders' responses to heavy metal stress.

The Effects of Cadmium Exposure on Fitness-Related Traits and Antioxidant Responses in the Wolf Spider, Pardosa pseudoannulata.

The objective of the present study was to assess the ecotoxicological responses of Pardosa pseudoannulata to a common environmental pollutant, cadmium. Third-instar spiderlings and adult spiders were exposed to sublethal concentrations of CdCl2 solution in their drinking water. The Cd content in P. pseudoannulata adults increased significantly with the number of days of exposure to a 0.2 mM CdCl2 solution, when exposed to 2 mM CdCl2 solution, the Cd content in the spiders increased sharply in the first two (male) or three (female) weeks, and then no significant changes were recorded following with the next three (male) or two (female) weeks exposure. Exposure of spiders to Cd contaminated drinking water resulted in reduced body mass, delayed development, fewer eggs and increased mortality. Significantly higher activities of superoxide dismutase, catalase and glutathione-S-transferase were recorded in the spiders after 7 day exposure to 0.2 mM CdCl2 solution. However, longer-term exposures or increased Cd concentrations did not result in significantly higher antioxidant enzyme activity relative to control treatment.

Transcriptome responses to elevated CO2 level and Wolbachia-infection stress in Hylyphantes graminicola (Araneae: Linyphiidae).

Hylyphantes graminicola is a resident spider species found in maize and cotton fields and is an important biological control agent of various pests. Previous studies have demonstrated that stress from elevated CO2 and Wolbachia infection can strongly affect spider species. Thus, based on CO2 levels (400 ppm, current atmospheric CO2 concentration and 800 ppm, high CO2 concentration) and Wolbachia status (Wolbachia-infected, W+ and Wolbachia-uninfected, W- ), we divided H. graminicola individuals into four treatment groups: W- 400 ppm, W- 800 ppm, W+ 400 ppm, and W+ 800 ppm. To investigate the effects of elevated CO2 levels (W- 400 vs W- 800), Wolbachia infection (W- 400 vs W+ 400), and the interactions between these two factors (W- 400 vs W+ 800), high-throughput transcriptome sequencing was employed to characterize the de novo transcriptome of the spiders and identify stress-related differentially expressed genes (DEGs). De novo assembly of complementary DNA sequences generated 86 688 unigenes, 23 938 of which were annotated in public databases. A total of 84, 21, and 157 DEGs were found among W- 400 vs W- 800, W- 400 vs W+ 400, and W- 400 vs W+ 800, respectively. Functional enrichment analysis revealed that metabolic processes, signaling, and catalytic activity were significantly affected by elevated CO2 levels and Wolbachia infection. Our findings suggest that the impact of elevated CO2 levels and Wolbachia infection on the H. graminicola transcriptome was, to a large extent, on genes involved in metabolic processes. This study is the first description of transcriptome changes in response to elevated CO2 levels and Wolbachia infection in spiders.