Effects Of Feeding Lemon Extract On Longevity,Gene Expression And Metabolism In Drosophila Melanogaster

Lemon extract(LE)is a natural extract of lemon fruit that contains a variety of active substances.Various forms of lemon extract have been shown to play a role in fighting cancer,improving cognitive dysfunction and aging-related ocular lesions.However,studies on the function and molecular mechanism of LE in Drosophila aging have not been reported.In order to investigate the possible mechanism of LE in regulating Drosophila aging,this study examined the effect of feeding different concentrations of LE on the lifespan of Drosophila,and selected the optimal concentration for relevant phenotypic assays and transcriptomic and metabolomic sequencing.Differentially expressed genes(DEGs)and differentially accumulated metabolites(DAMs)were also screened for functional enrichment after feeding LE.In addition,we analyzed the signaling pathway of DEGs and DAMs by combining transcriptomic and metabolomic data,and validated the pathway.The main findings are as follows:(1)0.05 g/L LE significantly prolonged the health span of Drosophila and improved aging-related phenotypes,such as increased resistance to oxidative stress and heat stress;and did not affect the food intake,fecundity,and body weight of Drosophila.(2)In transcriptomic sequencing,a total of 313.64 M raw reads were obtained from six sequencing libraries,resulting in 301.29 M high quality clean reads,with a total of97.19%-97.38% of clean reads being able to be compared to the Drosophila genome,with95.91%-96.21% of sequences having a unique genomic location.(3)Transcriptomics sequencing analysis showed that a total of 13682 protein-coding genes were obtained in 6 sequencing libraries,and 110 DEGs were screened after comparing,including 101 DEGs upregulated and 9 DEGs downregulated after feeding 0.05 g/L LE.Functional enrichment analysis revealed that DEGs were significantly enriched in a total of15 Kyoto Encyclopedia of Genes and Genome(KEGG)signaling pathways,including ascorbate and aldarate metabolism,hippo signaling pathway-fly,retinol metabolism,fatty acid biosynthesis,tyrosine metabolism,drug metabolism-other enzymes,including 12metabolism-related pathways.(4)Metabolomic sequencing analysis revealed that 43 DAMs were identified after feeding 0.05 g/L LE,including 15 up-regulated DAMs and 28 down-regulated DAMs.Functional enrichment analysis revealed that DAMs were significantly enriched to pyrimidine metabolism,folate biosynthesis,tyrosine metabolism,riboflavin metabolism,pantothenate and Co A biosynthesis,aminoacyl-t RNA biosynthesis,2-Oxocarboxylic acid metabolism,cysteine and methionine metabolism,purine metabolism,a total of 9 KEGG signaling pathways.(5)Co-mapping of DEGs and DAMs to the KEGG database revealed that ppo1 is enriched with Levodopa(L-dopa)in the tyrosine metabolism pathway.(6)ppo1 and L-dopa were significantly upregulated in Drosophila fed 0.05 g/L LE,and phenoloxidase activity,the tyrosine enzyme that catalyzes the hydroxylation of tyrosine to produce L-dopa,was significantly upregulated.In addition,direct feeding of L-dopa in vitro also resulted in a significant increase in the lifespan of Drosophila.In this study,we performed phenotypic assay in Drosophila fed 0.05 g/L LE,screened DEGs and DAMs through transcriptomic and metabolomic sequencing,and performed functional enrichment analysis and combined analysis of DEGs and DAMs.The results showed that LE may play a role in regulating aging through tyrosine metabolism pathway.This study provides a new reference for the involvement of natural plant extracts as drugs in the regulation of aging in Drosophila.