High Sucrose Feeding Induces Oxidative Stress And Mitochondrial Dysfunction Of Musca Domestica

There are many reports on metabolic diseases induced by high-sugar diet,but the mechanism of body damage caused by high-sugar intake is still unclear,and this scientific problem is worth to study.In this paper,Musca domestica(housefly)was selected to study the mechanism of body damage caused by high glucose intake.The studies elaborate on changes of growth and development,glycolipid metabolism and oxidative stress in housefly,with emphasis on mitochondrial function.The main contents and results of the studies are listed as follows:1)Cloning and identification of mitochondrial transcription factor A(TFAM)gene MdTFAM in housefly.The cDNA of MdTFAM gene(GenBank access number: MK519375)contains a 762 bp complete ORF(open reading frame),encoding 253 amino acid residues.The MdTFAM protein structure contains two tandem HMG(high mobility group)domains.qRT-PCR(quantitative real-time PCR)was employed to analyze the expression levels of MdTFAM in different developmental stages and tissues of housefly.The results showed that MdTFAM was highly expressed in egg stage and the intestinal and fat bodies of housefly.The gene was significantly up-regulated under ultraviolet(UV),doxorubicin hydrochloride(DOX)and cadmium chloride stress,suggesting that MdTFAM involves in maintaining redox balance in housefly.2)Effects of high-sugar diet on the growth and glycolipid metabolism in housefly.By adding high concentration of sucrose(0.47 M and 2.34 M)to the larval medium of housefly,it was found that the high-sugar diet induced larval weight loss,decreased survival rate and delayed pupation.After feeding a high-sugar diet for 12 h,the contents of glucose and trehalose in the larvae increased,but after resuming culture in normal medium for 24 h,the blood sugar resumed to the normal level.Moreover,high-sugar diet resulted in a significant decrease of glycogen content in housefly larvae,while the content of triglyceride(TAG)wassignificantly increased.We speculated that high-sugar diet induced sugar-lipid metabolism disorder in the housefly larvae.qRT-PCR determination of lipid metabolism related genes,ATGL(Adipose trigtyceride lipase)and FAS(Fatty Acid Synthase),expression levels,the results show that the two genes expression were down-regulated in the high-sugar treatment larvae,which further illustrate that the high-sugar diet can cause sugar larvae glucolipid metabolic disorders in housefly larvae.3)Effects of high-sugar diet on redox level and mitochondrial function of housefly larvae.Dose of 2.34 M sucrose feeding can reduce the movement ability,damaged the intestinal tissues,and caused fatty body DNA damage in the housefly.The content of Malondialdehyde(MDA)and reactive oxygen(ROS)increased significantly in the high-sugar treated larvae,indicating oxidative stress accrued.In addition,the activities of complex I(complex I,CI)and complex II(complex,CII)in the high-sugar treated housefly larvae decreased,and the levels of mitochondrial oxidative phosphorylation also declined,accompanied by abnormal mitochondrial morphology.Furthermore,the expression levels of the following mitochondria-related genes in housefly,MdTFAM,MdNrf2(nuclear factor-erythroid 2-related factor-2),MdSirt4(silent information regulator 4),and MdTPS(trehalose-6-phosphate synthase),were significantly down-regulated.The results further confirmed that mitochondrial dysfunction was induced by high-sugar diet in the housefly.In summary,our studies reveal that high-sugar intake will lead to sugar-lipid metabolism disorder in the housefly larvae,induce oxidative stress,and then damage mitochondrial function,resulting in energy metabolism disorder,which will delay housefly's growth and development,decreased survival rate.