Typical Organosilicone Stressed Response Of Crayfish (Procambarus Clarkii) In Antioxidant System And Related Gene Expression

Silicone chemicals are widely used in various commercial aspects due to the excellent properties,such as resistance of high and low temperatures.Silicone or silane coupling agents are important for different products and industrial and agricultural materials.Varisous silicone or siloxanes compounds are entering in the environment and ecosystems through human anthropogenic activities.The silicone toxicity to plant,aquatic animal and microbe occurs widely in environment since some of the silicones are hard to be degraded and can persist in the environment for a long time.The integrated rice-crayfish cultures have well developed in the China agricultural system,and the rice and crayfish intensive culture water may contain different types of silicone chemicals in the farmland ecosystem,which may causes stress on aquatic animal and plant.However,few studies are related to the aquatic animals in oxidant stress and its related gene expression.This paper reports the stressed responses of red swamp crayfish（Procambarus clarkii）in antioxidant responses and related gene expression under the exposure of three typical organosilicone（KH560,KH570 and D6）.1.A hydroponic experiment was employed to evaluate the effects of two typical silicone or silane coupling agents（3-Glycidoxypropyltrimethoxysilane（KH-560）and 3-Methacryloxypropyltrimethoxy silane（KH-570））on survival rate,antioxidant response and gene expression in crayfish.The crayfishes were grown in black aquaculture boxes containing different concentrations(0,10,100 and 1000 mg L^-1)of KH-560 and KH-570 for 72h,and then crayfish samples were harvested and separated into tissues of carapace,gill and muscle for analysis.The results showed that silicone significantly increased malondialdehyde（MDA）content in muscle by 17%-38%except for the treatment of 100 mg L^-1 KH-570,and reduced the survival rate of crayfish.Additionally,silicone KH-570 increased the activities of superoxide dismutase（SOD）,catalase（CAT）and peroxidase（POD）by 15%-31%,17%-35%,and 9%-46%,as well as the contents of ascorbate（As A）and glutathione（GSH）by 19%-31%,and 23%-29%respectively,in muscle tissue,and similar results occurred in KH-560.In the carapace,however,SOD activity was significantly decreased at high concentrations level of both silicone treatments.Moreover,silicon（Si）content was higher in the abdominal muscle of crayfish after silicone treatment.Assay of gene expression showed an obvious increasing expression of antioxidant related genes（Sod1,Sod2,Cat1,Cat2,and Pod1,Pod2）under silicone stress.The above results suggested that silicone caused an obvious stress response in crayfish in both biochemical and molecular levels.2.Dodecamethylcyclohexasiloxane（D6）is widely used daily in chemical industry and exists in the environment;however,its eco-toxicity is not well documented.A hydroponic experiment was performed to investigate the effects of D6 exposure(10–1000 mg L^-1)on oxidative stress induction and gene expression changes in crayfish.The results showed that superoxide dismutase（SOD）activity was enhanced by 20%–32%at low D6 exposure(10 mg L^-1)in muscle but reduced in gill tissue at high D6 exposure(1000 mg L^-1).High D6(1000 mg L^-1)also increased catalase（CAT）and peroxidase（POD）activities in muscle tissue by 14%–37%and 14%–45%,respectively,and the same trend was observed in the carapace and gill tissue of crayfish.The Malondialdehyde（MDA）,ascorbate（As A）,and glutathione（GSH）contents were increased by 16%–31%,19%–31%,and 21%–28%in the muscle of crayfish under D6 exposure.Additionally,silicon（Si）contents were increased in three organs（gill,carapace,and muscle）of crayfish.Related genes involved in enzyme and nonenzyme activities were detected,and when crayfish was exposed to D6,genes such as Sod3,Cat3,Pod3,and Gsh3 were up-regulated,while Asa3 and Oxido3 were significantly down-regulated in the muscle.The research results help us to understand the toxicity of D6 in crayfish and provide a basis for further research on the mechanism of D6-induced stress in crayfish and other aquatic organisms.