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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. [ABSTRACT FROM AUTHOR]

The effects of elevated CO2 concentration on spiders were studied using third-instar spiderlings of the wolf spider Pardosa astrigera L. Koch 1878 in CO2 climate chambers with two different concentrations of CO2 (low, 370 ppm and high, 750 ppm). The food intake and total developmental period of spiderlings reared at high CO2 concentration increased significantly, and the body length and weight of adult spiders decreased compared to those in the low-CO2 group. The oviposition rate of female P. astrigera and the hatching rate of eggs did not differ between the high- and low-CO2 groups, but the number of egg sacs and the total number of eggs produced by females from the high-CO2 group decreased. These results suggest that elevated CO2 concentrations are harmful to the growth, development, and reproduction of P. astrigera. [ABSTRACT FROM AUTHOR]

Only a few studies have examined the presence of endosymbionts in spiders (Araneae). We used PCR methods to assay for the presence of Wolbachia, Cardinium and Spiroplasma in 1000 spider individuals from China (including 16 families and 37 species). Of the species, 41.4% (15/37) contained one or more endosymbionts, Nephila clavata tested positive for all three endo symbionts, indicating that hereditary symbioses are extremely widespread in spiders. Align ment of the sequences obtained here with previously published alignments allowed us to establish phylogenetic trees for three symbiotic bacteria. The results showed that the Wolbachia found in infected spiders all belong to group A or B. The maximum parsimony(MP) tree showed that all Cardinium and Spiroplasma infecting spiders formed the same branch, indicating a very close genetic relationship between the two genera of symbiotic bacteria that exist in the spiders from different countries. However, the sequences of Spiroplasma from Chinese spiders showed a closer phylogenetic relationship and greater similarity to each other. [ABSTRACT FROM AUTHOR]