Japonica Under Lead Stress Of Digital Expression Profiling

At present, global water pollution is extremely serious. In many factors that cause water pollution, water pollution caused by release and migration of heavy metals is increasing obviously,of which damage is also increasing day by day. The lead (Pb) is one of the most toxic heavy metal, the harm is also obviously. The sources of lead pollution are extremely wide.The lead (Pb) is neurotoxic, and its toxicity is very serious. For humans, the toxicity of lead can affect each of our body systems and organs. Its influence is not only serious on the ultrastructure of cell, but also to nervous system. Therefore, the present research about lead toxicity has become a hot topic of heavy metal pollution in water. Previous research on the lead caused the body to produce "subclinical toxicity".To explore the changes in expression of genes and related metabolic pathways differ are caused by lead toxicity is very important to study toxicological mechanisms and repair mechanisms after lead damage from the molecular level.Dugesia japonica is Platyhelminthes, Turbellaria.Tricladida, which lives in freshwater. As freshwater pollution indication animal,Dugesia japonica play an important role to study environmental water sources of one of heavy metal pollutionThis experiment adopts the Dugesia japonica as the experimental animal. Firstly, we disposed experimental Dugesia Japonica under stree of Pb(80mg·L-1) in48h,used miRNeasy Mini Kit(217084) to extract total RNA and used Agilent2100to gauge the total RNA concentration and OD values.Then we used the Illumina system for RNA-Seq sequencing, obtained clean reads and compared the reads with the reference sequence. At the same time,we analysed gene sequencing expression quantity statistics, screening of differential gene. At last, GO was used for functional annotation of differentially expressed genes and the annotation results were classified by WEGO, KEGG was used for pathway analysis.The main results of this study are the following:1. By high-throughput sequencing, we used Caenorhabditis elegans as the comparison reference species.6,005,572clean reads were obtained in control group, accounting for 98.83%, and5,836,317clean reads in Pb treatment group. accounting for98.94%. Then, Consequently, there are3,259and3,353reads compared into the reference sequence, and that the unique match reads were1563and1544.2. By comparing the two sets of data, we obtained926differentially expressed genes. Compared to the control group, there are451up-regulated genes and475down-regulated genes in Pb treatment group. Through the GO function significant enrichment analysis, we found that there were409terms belong to"cellular component",555terms be part of "molecular function", and "biological process" contains552terms. Through the KEGG Pathway significant enrichment analysis,642genes were mapped to228different metabolic pathways. The metabolic pathway of richest is "Metabolic pathways" metabolic pathway, a total of135difference expression genes. The second is the "Ribosome" metabolic pathway, which has53different genes in total, and the "Oxidative phosphorylation" metabolic pathway has a total of38difference expression genes.3. By analyzing, in protein synthesis places, we found18downregulated expression and11upregulated expression in the large subunit of the ribosome in Pb stress groups,16upregulated expression and8downregulated expression in the small subunit of the ribosome; and15upregulated expression and18downregulated expression were found in the endoplasmic reticulum.The Pb stress-responsive genes may result in the disturbance protein synthesis and degradation.4. In the oxidative phosphorylation pathway, we found differentially expressed genes associated with the electron transfer chain complexes—NADH dehydrogenase (complex Ⅰ), succinate dehydrogenase (complex Ⅱ), cytochrome C reductase (complex Ⅲ), cytochrome C oxidase (complex Ⅳ) and ATP synthase (complex Ⅴ). In the Pb stress conditions, these differences in gene expression up or down is to maintain normal oxidative phosphorylation pathway.5. By the differential expression profile analysis, we found the lead stress major role ribosomes and mitochondria in cells. Affect cell structure and function of gene expression by affecting ribosome and the endoplasmic reticulum protein synthesis. In addition, the major component of the protein expression of mitochondrial oxidative respiratory chain, affecting mitochondrial function and induce apoptosis.