| Xanthotoxin(xanthotoxin,XAT)is a natural photosensitive toxin.Early studies found that XAT activated by long-wave ultraviolet can effectively inhibit the growth and development of pests so that they can not complete their life cycle,thus controlling the number of its population and reducing the harm to agriculture.At present,nematodes do great harm to agriculture and are difficult to control because of their short life cycle and large number of offspring.Therefore,on the basis of relevant literature,we selected Caenorhabditis elegans as a model organism,to evaluate the toxic effect of XAT on Caenorhabditis elegans.(1)Study on the toxicity of XAT to Caenorhabditis elegans eggs.In the early stage,two groups of experiments were set up in the light group and the dark group.The results of the dark group showed that all the eggs hatched and XAT had no inhibitory effect on the hatching of the eggs,so the dark group was abandoned.Based on the calculation of the results of the light group,three groups of concentrations were set: 60(75% egg hatching),80% egg hatching(50% egg hatching)and 100 μg/m L(25% egg hatching).The effect of XAT exposure for 48 hours on Caenorhabditis elegans was observed.(2)Study on the physiological indexes of Caenorhabditis elegans which continue to develop from eggs to adults.The results showed that XAT at 60,80 and 100 μg/m L could cause significant changes in head swing,body bending,offspring number,body length and body width of Caenorhabditis elegans.However,significant maldevelopment was observed only when the concentration of XAT was 80 and 100 μg/m L.(3)Study on the chronic toxicity of Caenorhabditis elegans induced by XAT.The results showed that 80 μg/m L and 100 μg/m L XAT could significantly up-regulate the level of ROS in Caenorhabditis elegans,and then lead to a significant increase in the contents of MDA,protein carbonyl and lipofuscin in Caenorhabditis elegans.60 μg/m L XAT could significantly increase the activities of SOD and CAT,while 80 μg/m L and 100 μg/m L XAT significantly inhibited the activities of SOD and CAT.(4)Study on the apoptosis of Caenorhabditis elegans induced by XAT.The results showed that only 60 μg/m L XAT could induce a significant increase in complex Ⅲ activity.However,XAT at 80 and 100 μg/m L could induce a significant decrease in complex Ⅰ andⅢ activity and mitochondrial membrane potential,while 80 and 100 μg/m L XAT could significantly increase the level of apoptosis.In addition,we also detected the effect of 80μg/m L XAT on apoptosis-related genes.The results showed that the pro-apoptotic genes ced-3 and ced-4 genes were significantly up-regulated compared with the control group.(5)Study on the effect of XAT on the intestinal tract of Caenorhabditis elegans.The results showed that 60,80,100 μg/m L XAT had no significant effect on intestinal permeability.XAT at 80 and 100 μg/m L caused significant damage to intestinal microvilli and intestinal epithelial cells.In addition,we also detected the effect of 80 μg/m L XAT on intestinal flora.The results showed that compared with the control group,80 μg/m L XAT could inhibit the number of intestinal bacteria and destroy the composition of intestinal bacteria.(6)Study on the effect of 80 μg/m L XAT on the whole RNA expression level of Caenorhabditis elegans.The results showed that compared with the control group,604 genes were up-regulated and 1214 genes were down-regulated after nematode treatment with 80 μg/m L XAT.To sum up,in the face of the current situation that there is little research on Caenorhabditis elegans by XAT,this study expounds the photoactivated toxic effect of XAT on Caenorhabditis elegans through transcriptome,which lays a foundation for future generations to carry out research. |
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