Study On The Effect Of Cadmium On Pardosa Pseudoannulata

As an important predator of rice pests,rice spiders play a key roles in controlling rice pests,such as rice planthopper and leafhopper.Cadmium(Cd)can be transferred and accumulated in spiders and affect their physiological and ecological traits,thus affecting its ecological regulation function to pests.However,the mechanism of toxic effects of Cd on spiders is not clear.This paper investigated the effects of cadmium on Pardosa pseudoannulata which is a perennial dominant species of rice spiders in rice fields in southern China,via an indoors simulated food chain,that is,Cd-medium – Drosophila – P.pseudoannulata.The spider venom gland is an important organ involved in immune,cerebral ganglion is the central nervous system of the spider and participates in the regulation of activities.The intestines is main organs for digestion and absorption of spider,where intestinal microorganisms is vital to digestion,absorption and immune function of spiders.The main detoxification enzymes and metallothionein are important bioactive substances for spiders to resist and alleviate the toxic effects of Cd and other heavy metals.Therefore,in this paper,we explored the effects of Cd stress on gene expression and function of differential expression gene(DEG)of spider venom gland and cerebral ganglion by transcriptome sequencing technology.We investigated the effects of Cd stress on community structure and function of intestinal microorganisms in spider through metatranscriptome technique.Meanwhile,the content of main detoxification enzymes and the metallothionein in spider were studied under Cd stress.Through those three aspects of systematic researches,this paper finally reveals the effects of Cd on P.pseudoannulata.The results are as follows:1.The short-term Cd stress induced the increase of bioactive substances including PO,GSH-PX,AchE,protease,and MT in P.pseudoannulata,while long-term Cd stress reduced the content of various bioactive substances.The bioactive substances distributed differently in spider body.Cadmium stress did not change the distribution of AchE,GSH-PX,PO and protease in different parts of P.pseudoannulata,while the MT's was changed.In subcellular compartments of P.pseudoannulata,Cd mainly affects the content of bioactive substances in cell mitochondria,microsomes,and cytoplasm.Cadmium stress induced the transformation of AchE,GSH-PX and PO from soluble proteins into membrane-bound proteins,and resulting in the transformation of protease and MT from membrane-bound proteins into soluble proteins.2.The results showed that the gene expression involving in oxidative phosphorylation pathway that associated with energy supply,Cytochrome P450 metabolism pathway which related to xenobiotic metabolism,glutathione metabolism pathway that associated with antioxidant and detoxification,cGMP-PKG signaling pathway and calcium signaling pathway which related to signal transduction,arginine metabolism pathway and ribosome pathways that related to neurotransmitter,and neurological diseases,were changed in cerebral ganglion transcriptome,under Cd stress.The DEGs in transcriptome of venom gland were significantly annotated to 11 GO terms and 7 KEGG pathways which associated with the immune function.Cadmium stress significantly changed the gene expression involving in epithelial cell maturation,mesenchyme migration,plasminogen activation,apoptosis,Rap1 signaling pathway and PPAR signaling pathway,all of which related to humoral immunity,cellular immunity and physical defense in P.pseudoannulata.3.The intestinal microorganisms of P.pseudoannulata was composed of 4 kingdoms,namely bacteria,viruses,eukaryotes and bacteria,including 46 phyla,97 classes,184 orders,339 families,470 genera,598 species.Among those,there were 281 species in bacteria,221 species in eukaryotes,81 species in viruses and 15 species in archaea.Proteobacteria and firmicutes were the main bacteria.Wolbachia endosymbiont of drosophila ananassae and wolbachia endosymbiont of callosobruchus were firstly found parasitic in intestines of P.pseudoannulata.Ascomycota was the dominant gates in eukaryotic microorganisms.Poxviridae was the dominant family virus.Euryarchaeota was a dominant gates in archaea.Under Cd stress,the relative abundance expression of eukaryotic,bacteria and viruses were decreased by 0.14%,1.22% and 2.52% respectively,while the archaea's was increased by 99.16%.The rmoplasmatales archaeon SCGC AB-540-F20 and archaeon GW2011_AR20 were two archaeas which were newly grown under Cd stress.The results showed that Cd significantly changed the community structure of intestinal microorganisms in P.pseudoannulata.4.From metatranscriptome of intestinal microorganisms in P.pseudoannulata,a total of 41153 unigenes were annotated to 25 major categories in the eggNOG database,including protein turnover,lipid transport and metabolism,and energy generation.A total of 1519 DEGs were obtained,including 770 up-regulated genes and 749 down-regulated genes.The KEGG annotation results showed that the expression of genes in patyways were significantly changed by Cd,which including involving in metabolism and synthesis of nutrients pathways,such as carbon,sugar,and proteins,including carbon metabolism,biosynthesis of amino acids,purine metabolism,ditrate cycle(TCA cycle),pyruvate metabolism and glycolysis/gluconeogenesis,and so on,oxidative phosphorylation pathway related to energy supply,glutathione metabolism pathway associated with antioxidant detoxification.In conclusion,cadmium affect the content of GSH-PX and MT in P.pseudoannulata colud by affecting the expression of genes in glutathione metabolism patyway which related anti-oxidation and detoxification function;Cadmium affect the content of AchE and PO in P.pseudoannulata colud through affecting the expression of genes related to the nerve regulation and immune function,respectively.Cadmium affects the content of protease in P.pseudoannulata colud by affecting the gene expression related to the metabolic function of intestinal microorganism.We comprehensively analyzed the effect of cadmium that transmitted through food chain on P.pseudoannulata which is the dominant spider in the paddy field.