Effects Of Cadmium Stress On Physiological Characteristics,Antioxidant Capacity And DNA Methylation Of Drosophila Melanogaster

Cadmium is a common heavy metal that has been identified as the first carcinogen by the International Association for the Study of Cancer.When the human body ingests trace amounts of cadmium,cadmium can accumulate in many organs such as kidney,liver,lung,etc.,as well as in the reproductive system,cardiovascular system,and nervous system due to its long half-life,thereby interfering with normal biological functions.Excessive metal stress can cause various diseases such as lung inflammation,cancer,and cardiovascular disease.At present,the mechanism of the toxic effects of heavy metal cadmium on the body mainly involves its induction of ROS production,resulting in oxidative damage,interference with intracellular ion balance,and causing epigenetic variation.Drosophila melanogaster is often used for genetic research in the biological sciences,and it has been one of the best organisms for human disease and toxicology research in the past few decades.There is a wide range of conserved genes and developmental mechanisms between D.melanogaster and humans.When comparing D.melanogaster with human genomes,it is found that two-thirds of genes(including cancer-related genes)in humans cause human diseases.All can find similar genes in Drosophila.In this study,Canton-S strain of Drosophila melanogaster was selected as the experimental material,and 0,13,26,and 52 mg/L cadmium were used to treat F0 fruit fly with different treatments(male,male,and male).F1 generation After destressing,the changes in climbing power,anti-starvation,body weight,number of eclosion and sex ratio of F0 generation and F1 generation fruit fly and the T-AOC of F0 generation and F1 generation fruit fly were examined after cadmium stress.The activity changes of GSH-Px were investigated to investigate the effects of heavy metal cadmium on physiological characteristics and antioxidant capacity of D.melanogaster and its toxic effects.On this basis,D.melanogaster genomic DNA was extracted and the whole genome bisulfite methylation sequencing method was used to analyze the effect of cadmium on the whole genome DNA methylation level of D.melanogaster.Experimental results show:(1)In terms of physiological characteristics,the climbing power,hunger resistance,and body weight of F0 fruit fly flies under different concentrations(0,13,26,52 mg/L)of cadmium were significantly reduced as the treatment concentration increased(P<0.05).Compared to the control group,cadmium treatment significantly reduced the climbing power of the F1 fly(P<0.05).In the cadmium-treated group(13,26,52 mg/L),after the treatment with 26 mg/L cadmium,the climbing power of F1 males in the female and male-female treatment groups increased significantly(P<0.05).This shows that the effect of cadmium stress on the climbing power of D.melanogaster can extend to F1 generation at least;compared with the control group,the hunger resistance of females in the male,male and male-male-treated groups are not significantly different.The results showed that the effect of cadmium stress on the hunger resistance of D.melanogaster was eliminated in the F1 generation.In the female and male treatment groups(26 mg/L),the body weight of male flies significantly increased(P<0.05).In the treatment group(26 mg/L),body weights of male and female fruit flies significantly decreased(P<0.05),indicating that the effect of cadmium stress on the body weight of D.melanogaster can continue to the F1 generation;the eclosion rate of D.melanogaster under cadmium stress Decline and concentration-dependent.In summary,the cadmium stress can reduce the climbing power,anti-fighting force,body weight,and number of feathers of D.melanogaster.At the same time,it induces the male and female sex ratio imbalance.(2)In terms of antioxidant capacity,T-AOC activity of F0 fruit fly induced by cadmium stress was significantly decreased(P<0.05),and T-AOC activity of F1 female flies was observed in female treatment group(13,26 mg/L).Significantly increased(P<0.05),the T-AOC activity of male flies was not significantly different from that of the control group,indicating that the effect of cadmium stress on Drosophila melanogaster was gender-differentiated;the GSH-Px activity of F0 generation flies increased first and then decreased.The trend was that both GSH-Px in F1 generation flies decreased,and GSH-Px in male and female flies increased significantly in males and females(52 mg/L)after cadmium treatment(13,26,52 mg/L).It shows that the cadmium stress breaks the balance of antioxidant defense system of Drosophila melanogaster,leading to the decline of antioxidant function.(3)In terms of methylation of whole genome DNA,the sequencing results showed that the degree of methylation of D.melanogaster was very low,ranging from 0.10 to 0.14%.After cadmiums stress on female flies,the average degree of methylation in the whole genome decreased.The analysis of the degree of methylation under different sequences(CG,CHG,CHH)showed that the number and proportion of methylated Drosophila melanogaster in CHH sequence environment were the most,followed byCHH sequence environment,and the level of CHG sequence environment was the least.At the same time,796 DMGs(Differentially methylated gene)were identified by tDMR analysis,of which 238 were up-regulated and 558 were down-regulated,DMGs were identified by GO,involving three aspects of biological processes,molecular functions and cell components.After further screening for DMR,six resistance-associated DMGs were identified,namely Cyp4dl4,Cyp6ul,Cype,GstSl,GstT4,and ABCB7,belonging to cytochrome P450(CYP)and glutathione S transferase(GST),respectively.The ATP-binding cassette(ABC),which belong to the three major superbugs involved in the detoxification of insects.This study examined the effects of heavy metal cadmium on related physiological characteristics and antioxidant capacity of D.melanogaster through the detection of the effects of cadmium stress on the climbing power,anti-fighting force,body weight,number of eclosion,sex ratio and related antioxidative enzyme activity.To investigate the toxic effects and toxicological mechanisms of heavy metal cadmium on D.melanogaster,and to use the whole genome bisulfite methylation sequencing method to study the differences in DNA methylation levels and pattern changes at the level of cadmium stress.A more in-depth study of the toxicological effects of cadmium stress on D.melanogaster and its mechanism of action provided experimental evidence,and laid the experimental foundation for further investigation of the whole genome DNA methylation system of D.melanogaster and the epigenetic variation induced by environmental factors.