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

Long-term cadmium stress influenced the immune response of Pardosa pseudoannulata by modulating its gut microbiota and hemolymph metabolome

Cadmium (Cd) is a common environmental heavy metal pollutant known for its toxic effects on various plants and animals. Cd contamination also poses a threat to Pardosa pseudoannulata, a predator in rice paddies. Results indicate that Cd pollution significantly reduced the levels of Metallothionein, phenoloxidase, and Ca2+. Furthermore, through metabolomics and 16S rDNA sequencing, alterations in the gut microbiota and immune-related metabolites of P. pseudoannulata were identified. The abundance of harmful bacteria such as Staphylococcus increased significantly, while levels of l-Tyrosine, glutathione disulfide, l-Dopa, among others, decreased markedly. Pearson correlation analysis revealed significant associations between various gut microbes and immune-related metabolites, suggesting that Cd may alter the immune system of P. pseudoannulata by modulating its gut microbiota.

Molecular and Proteomic Analyses of Effects of Cadmium Exposure on the Silk Glands of Trichonephila clavata

Cadmium (Cd) is a pervasive heavy metal pollutant released into the environment through industrial activities such as mining, smelting, and agricultural runoff. This study aimed to investigate the molecular and metabolic impacts of Cd exposure on the silk glands of Trichonephila clavata, a species renowned for producing silk with exceptional mechanical properties. Cd accumulation in spider bodies and silk glands was significantly higher in the low- and high-Cd groups compared to controls, with a dose- and time-dependent increase. Oxidative stress markers, including superoxide dismutase, glutathione peroxidase, peroxidase, and malondialdehyde, were significantly elevated, indicating a robust stress response. Proteomic analysis identified 2498 proteins, with 227 differentially expressed between Cd-treated and control groups. Key metabolic pathways, including glutathione metabolism, cysteine and methionine metabolism, and amino acid biosynthesis, were significantly disrupted. Downregulation of enzymes such as glutathione synthase and S-adenosylmethionine synthetase highlighted oxidative imbalance and impaired sulfur metabolism, indicating disruptions in redox homeostasis and energy metabolism critical for silk production. These findings demonstrate that Cd exposure alters oxidative stress responses, disrupts key metabolic pathways, and impairs silk gland functionality at multiple molecular levels. This study advances the understanding of the impact of heavy metal stress on spider physiology and provides a foundation for further research on the ecological implications of Cd contamination.

Glyphosate-based herbicides reduced overwintering population and reproduction of agrobiont spiders

Spiders are important in ecosystem and serve as predators in the biological control of pest insects in agroecosystem, where they encounter various harsh challenges including pesticides and low temperature in winter. Glyphosate-based herbicides (GBH) are widely and frequently applied to diminish weeds, exposing spiders a disturbed habitat, especially to overwintering spiders. We conducted a study combining field surveys and lab assays, to assess the effects of a GBH on the overwintering of the agrobiont wolf spider, Pardosa pseudoannulata. The GBH significantly reduced the overall overwintering spider population by about 69 %, and reduced the number of vulnerable juveniles by about 80 %. The survivors exhibited substantial fitness costs such as reproductive dysfunctions and enhanced oxidative stress responses. We then mimicked the overwinter process in lab. We housed spiders on soil patches with and without weeds to examine whether weeds contributed to the GBH's sublethal effects. Spiders overwintered independent of weeds when GBH was not applied. When GBH was applied before or during overwintering, juvenile spiders overwintered in weedy habitats exhibited reduced survival and fecundity, and increased oxidative stress compared to their counterparts in weed-free habitats. Therefore, GBH-containing weeds contributed to the persistent adverse effects of GBH on overwintering spiders. The findings revealed the cross-talk among weeds, herbicides, low temperature, and non-target organisms. The study provides novel information on the environmental risk assessment of pesticides and rational scheduling of pesticide application.

Transcriptomic and metabolomic profiles of Pirata subpiraticus in response to copper exposure

Copper (Cu) contamination represents a persistent and significant form of heavy metal pollution in agricultural ecosystems, posing serious threats to organisms in current society. Spiders serve as crucial biological indicators for assessing the impact of heavy metals-induced toxicity. However, the specific molecular responses of spiders to Cu exposure and the mechanisms involved are not well understood. In our study, the wolf pond spiders, Pirata subpiraticus, were exposed to Cu for 21 d, resulting in a notable decline in survival rates compared with the control (n = 50, p < 0.05). We observed an increased expression of enzymes like glutathione peroxidase and superoxide dismutase (p < 0.05), signaling a strong oxidative stress response crucial for counteracting the harmful effects of reactive oxygen species. This response was corroborated by a rise in malondialdehyde levels (p < 0.05), a marker of lipid peroxidation and oxidative damage. Transcriptomic and metabolomic analyses revealed 2004 differentially expressed genes (DEGs) and 220 metabolites (DEMs). A significant number of these DEGs were involved in the glutathione biosynthetic process and antioxidant activity. A conjoint analysis revealed that under the Cu stress, several important enzymes and metabolites were altered (e.g., cathepsin A, legumain, and lysosomal acid lipase), affecting the activities of key biological processes and components, such as lysosome and insect hormone biosynthesis. Additionally, the protein interaction network analysis showed an up-regulation of processes like the apoptotic process, glutamate synthase activity, and peroxisome, suggesting that spiders activate cellular protective strategies to cope with stress and maintain homeostasis. This study not only deepens our understanding of spider biology in the context of environmental stress but also makes a significant contribution to the field of environmental stress biology.

Effects of the toxic metal zinc on the growth, development, and reproduction of the wolf spider Pardosa laura through its food Drosophila melanogaster

In recent years, toxic metal pollution has become a serious problem, and its influence on human society and the ecological environment has become a hot topic for people. Toxic metal pollution is ubiquitous in the environment, and it can affect the growth, development, and reproduction of organisms through food chain transmission. In this study, we used ZnSO4 and set three different Zn concentrations [0 mg/mL (CK), 0.25 mg/mL, and 0.50 mg/mL] to study the enrichment of toxic zinc metal in the wolf spider Pardosa laura through the food chain (medium-Drosophila melanogaster-P. laura) and the effects on the growth, development, and reproduction of D. melanogaster and P. laura. The results of the study showed that the Zn content in D. melanogaster and P. laura significantly increased with the increase of Zn concentration in the culture medium, reflecting the obvious food chain enrichment phenomenon. The inhibitory effect of zinc treatment on the growth, development, and reproduction of D. melanogaster was significant and more pronounced with increasing Zn concentration. The transfer of zinc through the food chain also had a significant inhibitory effect on the growth, development, and reproduction of P. laura. The developmental duration and preoviposition period were significantly prolonged. Moreover, the survival rate, body size, and egg laying amount were significantly reduced. This study will enrich and improve the research on the effects of toxic Zn metal pollution on spiders and provide a theoretical basis for monitoring and evaluating the environmental quality using farmland spiders.

Toxic effect of Cd burden on the gut microflora and immune responses of wolf spider Pardosa pseudoannulata

Spiders are dominant predators in the paddy ecosystem, but the immunotoxicity induced by environmental contaminants like heavy metals is still largely unknown. The gut microbiota-host interaction was the basic immune mechanism discovered in the arthropods. Here, we investigated the gut microflora and immune responses of wolf spider Pardosa pseudoannulata under Cd burden. Cd exposure was identified to shape the gut microbial community structure of spiders, with increased levels of Firmicutes and pathogens, and decreased levels of Proteobacteria and Bacteroidota. The alteration of microbiota-derived immune messengers like peptidoglycan (PGN) was also observed. ELISA and hemolymph metabolomic analysis showed that the activities of immune effectors phenoloxidase (PO) and lysozyme (LZM) and the abundance of tyrosine derivates were decreased, which indicated the suppression of Cd on the melanization immune response of spiders. Correlation analysis revealed a close relationship between the impaired immune system and the disordered microbiota. This study provides insight into the underlying mechanisms of the gut microflora-immune system interaction of P. pseudoannulata in response to Cd burden.

Transcriptome Changes Reveal the Toxic Mechanism of Cadmium and Lead Combined Exposure on Silk Production and Web-Weaving Behavior of Spider A. ventricosus

The combined exposure of multiple metals imposes a substantial burden on the ecophysiological functions in organisms; however, the precise mechanism(s) remains largely unknown. Here, adult female A. ventricosus were exposed to single and combined exposure to cadmium (Cd) and lead (Pb) through the food chain. The aim was to explore the combined toxicity of these metals on silk production and web-weaving behavior at physiological, cellular morphological, and transcriptomic levels. The Cd and Pb combined exposure significantly inhibited the ability of silk production and web-weaving, including reduced silk fiber weight and diameter of single strands, lowered weaving position, induced nocturnal weaving, and increased instances of no-web, and showed a dose-response relationship on the Cd and Pb bioaccumulation. Concurrently, severe oxidative stress and degenerative changes in cells were observed. In addition, the combined pollution of Cd and Pb demonstrated synergistic effects, influenced by variations in concentration, on the enrichment of metals, inhibition of silk weight, oxidative damage, and cellular degeneration. At the transcriptome level, the upregulated ampullate spidroin genes and downregulated amino acid anabolic genes, upregulated Far genes and downregulated cytoskeleton-related TUBA genes, and overexpressed AChE and Glu genes may tend to present promising potential as biomarkers for silk protein synthesis, cellular degeneration, and neurotransmitter induction. This study offers an enormous capability for a comprehensive understanding of the eco-toxicological effects and mechanisms of multiheavy metals pollution.

Integrated transcriptome and proteome unveiled distinct toxicological effects of long-term cadmium pollution on the silk glands of Pardosa pseudoannulata

Cadmium (Cd) induces severe soil pollution worldwide and exerts adverse effects on paddy field arthropods. Spiders grant a novel perspective to assess the Cd-induced toxicity, yet the impacts of long-term Cd stress on spider silk glands and its underlying mechanism remain elusive. The study showed that Cd stress enervated the antioxidant system in the spider Pardosa pseudoannulata, manifested as the decreases of glutathione peroxidase and peroxidase, and the increase of malonaldehyde (p < 0.05). In addition, a total of 1459 differentially expressed genes (DEGs) and 404 differentially expressed proteins (DEPs) were obtained from the silk glands' transcriptome and proteome. DEGs and DEPs encoding spidroin (e.g., tubuliform spidroin and ampullate spidroin) and amino acids metabolism (e.g., alanine, proline, and glycine) were distinctively down-regulated. Further enrichment analysis verified that Cd stress could inhibit amino acid metabolism via the down-regulation of several key enzymes, including glutathione synthase, methylthioadenosine phosphorylase, S-adenosylmethionine synthetase, etc. In addition, the hedgehog signaling pathway regulating cellular growth and development was down-regulated under Cd stress. A protein-protein interaction network showed that long-term Cd stress could inhibit some key biological processes in the silk glands, including peptide biosynthetic process and cytoskeleton part. Collectively, this comprehensive study established an effective animal detection model for evaluating Cd-induced toxicity, presented key biomarkers for further validation, and provided novel insights to investigate the molecular mechanisms of spiders to Cd pollution.

Transcriptomic analysis of cadmium toxicity and molecular response in the spiderling of Pirata subpiraticus

Cadmium (Cd) is a kind of toxic heavy metal widely distributed in the environment, posing life-threatening challenges to organisms. The paddy field spider is a natural enemy of pests and an essential component of rice biodiversity. Nonetheless, the effects of Cd stress on the postembryonic development of spiders and its detailed mechanism remain to be investigated. In the present study, we found that Cd stress posed adverse impacts on the growth indicators (e.g., carapace length, development duration, and survival rate) and increased the levels of three antioxidants (i.e., superoxide dismutase, glutathione S-transferase, and glutathione peroxidase) in the spiderlings of Pirata subpiraticus. An in-depth transcriptome analysis was employed in the study, and the results displayed that differentially expressed genes (DEGs) involved in postembryonic morphogenesis, development involved in symbiotic interaction, postembryonic development, and growth were distinctively altered under Cd stress. Further enrichment analysis showed that Cd exposure could activate the apoptosis pathway in the spider via the up-regulation of several key factors, including caspase-10, α-tubulin, actin, etc. In addition, we demonstrated that the increased level of glutathione-related enzymes in spiderlings was caused by the activation of glutathione metabolic pathway. The altered hedgehog signaling pathway might affect cell proliferation, tissue patterning, and development of spiderlings. Further protein interaction network displayed that Cd stress could affect multiple biological processes in spiderlings, particularly cellular response to stimulus and system development. To sum up, this study can provide multi-level perspectives to understand the toxicity of Cd on the growth and development of spiders.

Toxic effects of the combined cadmium and Cry1Ab protein exposure on the protective and transcriptomic responses of Pirata subpiraticus

Cadmium (Cd) pollution poses a serious threat to agricultural production and paddy field fauna. Crystalline proteins (e.g., Cry1Ab and Cry1Ac) are secreted by Bacillus thuringiensis, which can manage pests via a complicated toxic mechanism and have been widely used for pest control due to the commercialization of transgenic crops (e.g., cotton and rice) that expresses Bt insecticidal proteins. Nonetheless, studies on the effects of combined stress of Cd and Cry1Ab protein on field indicator species are limited. In the present study, we showed that spiders, Pirata subpiraticus, fed with Cd-containing flies+Cry1Ab had dramatically higher Cd accumulation than that in the spiders fed with Cd-containing flies (p < 0.05). In addition, the enrichment of Cd led to the activation of the protective mechanism by elevating the concentrations of glutathione peroxidase, glutathione S-transferase, and metallothionein in the spiders (p < 0.05). An in-depth transcriptome analysis revealed that the activities of ion metal binding proteins, transporters, and channels might play essential roles in the Cd accumulation process. More importantly, the higher Cd concentration in the combined Cd+Cry1Ab exposure prolonged developmental duration of P. subpiraticus, due to the down-regulated cuticle proteins (CPs) encoding genes involved in the molting process, which was regulated by a series of putative transcriptional factors such as ZBTB and zf-C2H2. Collectively, this integrated analysis illustrates that the combined Cd+Cry1Ab exposure increases the adverse effects of Cd stress on the growth, antioxidase, and CPs encoding genes of P. subpiraticus, thus providing a research basis and prospect for the rationality of transgenic Cry1Ab crops in the cultivation of heavy metal contaminated soil.

Integrated transcriptomics and proteomics provide new insights into the cadmium-induced ovarian toxicity on Pardosa pseudoannulata

Cadmium (Cd) pollution is intractable heavy metal pollution in the farmland ecosystem, posing a life-threatening challenge to the paddy field organisms. Spiders are riveting animal biomarkers for evaluating Cd-induced toxicity, yet the effects of long-term Cd toxicity on spider reproductive function and its underlying mechanism remain unclear. In the present study, we found that Cd exposure impaired the antioxidant enzyme system in the wolf spider Pardosa pseudoannulata and decreased the concentration of four antioxidant enzymes (catalase, glutathione peroxidase, superoxide dismutase, and peroxidase) (p < 0.05). The content of vitellogenin and the number of hatched spiderlings were also dramatically reduced under Cd stress (p < 0.05), indicating that Cd stress could vitiate the fecundity of P. pseudoannulata. Moreover, a total of 10,511 differentially expressed genes (DEGs) and 391 proteins (DEPs) were yielded from the ovarian transcriptome and proteome, and a mass of genes and proteins involved in protein processing in endoplasmic reticulum (ER) were significantly down-regulated. DEGs and DEPs directly encoding the antioxidant enzyme system and/or vitellogenesis were also distinctively down-regulated. In addition, we illustrated that the PI3K-AKT signaling pathway might play a crucial role in regulating protein synthesis, cell cycle, growth, differentiation and survival in P. pseudoannulata. The effects of protein processing in ER and PI3K-AKT pathways could further trigger transcriptional factor Forkhead shackling the protein synthesis and cell growth process. Collectively, this integrated analysis identified the Cd-induced reproductive toxicity on P. pseudoannulata and provided multifaceted insights to investigate the molecular mechanisms of spiders to Cd pollution.

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.

Transcriptome sequencing reveals the effects of cadmium toxicity on the cold tolerance of the wolf spider Pirata subpiraticus

As the predominant predator of pests in rice fields, spiders have been exposed to cadmium (Cd) pollution for a long time. The livability of spiders during the overwintering period is closely related to population growth in spring, but the effects of Cd on spider's survival of cold hardness and the underlining mechanism remain unclear. In the present study, we found that some growth parameters (body length, width, mass and livability) in the wolf spider Pirata subpiraticus were altered distinctively under Cd stress. To investigate the effects of Cd toxicity on the spider at molecular levels, RNA-sequencing was performed on the spiderlings undergoing ambient temperature alterations. Transcriptome data showed that a total of 807 differentially expressed genes (DEGs) were yielded in the comparison. The obtained DEGs were mainly linked with metabolism-related process, including oxidoreductase activity and lipid transport, and 25 DEGs were associated with the reported cryoprotectants, including glycerol, arginine, cysteine, heat shock protein, glucose and mannose. Growth factors (insulin growth factor, platelet-derived growth factor and transforming growth factor) and cytochrome P450 encoding genes were dramatically expressed in the spider. Furthermore, transcriptional factors (TFs) family were characterized according to the transcriptomic profile, and ZBTB TFs were represented the most distinctive alterations in the characterized genes. Collectively, our study illustrated that Cd poses disadvantageous effects on the growth of P. subpiraticus at cold ambient temperature, and the spiders are capable of responding to the adverse Cd stress by expressing the genes involved in the metabolism of energy substances, cryoprotectants and immune-related components.

Mul-tiomics analysis of cadmium stress on the ovarian function of the wolf spider Pardosa pseudoannulata

Cadmium (Cd) pollution is widespread in paddy filed soil in China. In this study, the toxicity of Cd with regard to the female reproductive system of paddy spider Pardosa pseudoannulata was investigated by means of multi-omics analyses (transcriptome, proteome, and miRNAs). Decreased activities of detoxifying enzymes including peroxidase (POD), Glutathione S-transferases (GST), and superoxide dismutase were detected in the ovary of P. pseudoannulata. Of these, GST and POD were consistently down-regulated at the transcriptional and translational levels. Vitellogenin content and fecundity of the spider were also reduced by Cd burden. Five vitellogenin encodes genes were down-regulated while only vitellogenin-6 protein was up-regulated. But protein lipovitellin-1, the main composition of vitellin, was down-regulated. In addition, the correlation between the mitogen-activated protein kinase (MAPK) signaling pathway and Cd stress was identified. A down-regulated gene that encoding connector of kinase to AP-1 in the MAPK signaling pathway was regulated by the up-regulated miRNA (miRNA id: miRNA dan-miR- 318>der-miR-318>dgr-miR-318>dme-miR-318-3p > dmo-miR-318>dpe-miR-318>dps-miR-318>dse-miR-318>dsi-miR-318>dvi-miR-318>dwi-miR-318>dya-miR-318). In conclusion, Cd stress possesses distinct female reproductive toxicity on P. pseudoannulata through impairing antioxidant system and synthesis of vitellin.

Identification, genomic organization and expression pattern of glutathione transferase in Pardosa pseudoannulata

The pond wolf spider, Pardosa pseudoannulata, is one of the dominant natural enemies in farmlands and plays important roles in controlling a range of insect pests. The spider is less sensitive to many insecticides than the target pests such as the brown planthopper, Nilaparvata lugens. The different sensitivity to a certain insecticide between species is mostly attributed to the differences in both molecular targets and detoxification enzymes. As one of the most important detoxification enzymes, glutathione transferases (GSTs) play a key role as phase II enzyme in the enzymic detoxification in organisms. Until now, there are few studies on spiders' GSTs, limiting the understanding of insecticide selectivity between insect pests and natural enemy spiders. In this study, based on the transcriptome and genome sequencing of P. pseudoannulata, thirteen full-length transcripts encoding GSTs were identified and analyzed. Interestingly, Delta family, which is thought to be specific to the Insecta, was identified in P. pseudoannulata. Further, vertebrate/mammalian-specific Mu family was also identified in P. pseudoannulata. The mRNA expression levels of cytosolic GSTs in different tissues were determined, and most GST genes were abundant in the gut and the fat body. To investigate GST candidates involving in insecticide detoxification, the mRNA levels of cytosolic GSTs were tested after spiders' exposure to either imidacloprid or deltamethrin. The results showed that PpGSTD3 and PpGSTT1 responded to at least one of these two insecticides. The present study helped understand the function of GSTs in P. pseudoannulata and enriched the genetic information of natural enemy spiders.

Combined effects of elevated CO2 concentration and Wolbachia on Hylyphantes graminicola (Araneae: Linyphiidae)

The increasing concentration of carbon dioxide in atmosphere is not only a major cause of global warming, but it also adversely affects the ecological diversity of invertebrates. This study was conducted to evaluate the effect of elevated CO2 concentration (ambient, 400 ppm and high, 800 ppm) and Wolbachia (Wolbachia-infected, W+ and Wolbachia-uninfected, W-) on Hylyphantes graminicola. The total survival rate, developmental duration, carapace width and length, body weight, sex ratio, net reproductive rate, nutrition content, and enzyme activity in H. graminicola were examined under four treatments: W- 400 ppm, W- 800 ppm, W+ 400 ppm, and W+ 800 ppm. Results showed that Wolbachia-infected spiders had significantly decreased the total developmental duration. Different instars showed variations up to some extent, but no obvious effect was found under elevated CO2 concentration. Total survival rate, sex ratio, and net reproductive rate were not affected by elevated CO2 concentration or Wolbachia infection. The carapace width of Wolbachia-uninfected spiders decreased significantly under elevated CO2 concentration, while the width, length and weight were not significantly affected in Wolbachia-infected spiders reared at ambient CO2 concentration. The levels of protein, specific activities of peroxidase, and amylase were significantly increased under elevated CO2 concentration or Wolbachia-infected spiders, while the total amino content was only increased in Wolbachia-infected spiders. Thus, our current finding suggested that elevated CO2 concentration and Wolbachia enhance nutrient contents and enzyme activity of H. graminicola and decrease development duration hence explore the interactive effects of factors which were responsible for reproduction regulation, but it also gives a theoretical direction for spider's protection in such a dynamic environment. Increased activities of enzymes and nutrients caused by Wolbachia infection aids for better survival of H. graminicola under stress.

Transcriptome analysis reveals the molecular response to cadmium toxicity in P. pseudoannulata

Cadmium (Cd) can be transferred and accumulated in spiders, posing a survival risk to them. To analyze potential biological damage caused by Cd accumulation and relevant detoxification strategies employed by spiders in response to Cd exposure, we conducted transcriptome analysis of the 5th instar spider P. pseudoannulata, a common spider species playing a vital role in natural pest control in agricultural fields of southern China. We obtained 92,778 unigenes with an average length of 1104 bp and identified 302, 655, and 424 differentially expressed genes (DEGs) in the spiders fed with Cd-containing fruit flies for 2, 5, and 8 days, respectively. Results showed that the body mass of Cd-containing P. pseudoannulata were reduced when compared with controls, presumably due to delayed maturation of tissues and organs. Meanwhile, functional analysis of DEGs indicated that Cd may have a negative effect on neural signal transduction and molt cycle of the spider. For defense strategies, detoxification enzymes like glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), and P450, and typical proteins like heat shock protein and metallothionein were all differentially expressed in response to Cd stress. Besides, innate immune responses like toll-like receptor signaling pathways were also upregulated. Multiple critical Cd-responsive genes involved in biological damage, detoxification, and immune response were identified, providing referable foundation for further research on Cd toxicity to P. pseudoannulata.

Transcriptome assembly and expression profiling of the molecular responses to cadmium toxicity in cerebral ganglia of wolf spider Pardosa pseudoannulata (Araneae: Lycosidae)

Cadmium (Cd) is a heavy metal that can cause irreversible toxicity to animals, and is an environmental pollutant in farmlands. Spiders are considered to be an excellent model for investigating the impacts of heavy metals on the environment. To date, the changes at the molecular level in the cerebral ganglia of spiders are poorly understood. Cd exposure leads to strong damage in the nervous system, such as apoptosis and necrosis of nerve cells, therefore we conducted a transcriptomic analysis of Pardosa pseudoannulata cerebral ganglia under Cd stress to profile differential gene expression (DGE). We obtained a total of 123,328 assembled unigenes, and 1441 Cd stress-associated DEGs between the Cd-treated and control groups. Expression profile analysis demonstrated that many genes involved in calcium signaling, cGMP-PKG signaling, tyrosine metabolism, phototransduction-fly, melanogenesis and isoquinoline alkaloid biosynthesis were up-regulated under Cd stress, whereas oxidative phosphorylation-related, nervous disease-associated, non-alcoholic fatty liver disease-associated, and ribosomal-associated genes were down-regulated. Here, we provide a comprehensive set of DEGs influenced by Cd stress, and heavy metal stress, and provide new information for elucidating the neurotoxic mechanisms of Cd stress in spiders.

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.