Transcriptional responses in the hepatopancreas of Eriocheir sinensis exposed to deltamethrin

Abstract

Deltamethrin is an important pesticide widely used against ectoparasites. Deltamethrin contamination has resulted in a threat to the healthy breeding of the Chinese mitten crab, Eriocheir sinensis. In this study, we investigated transcriptional responses in the hepatopancreas of E. sinensis exposed to deltamethrin. We obtained 99,087,448, 89,086,478, and 100,117,958 raw sequence reads from control 1, control 2, and control 3 groups, and 92,094,972, 92,883,894, and 92,500,828 raw sequence reads from test 1, test 2, and test 3 groups, respectively. After filtering and quality checking of the raw sequence reads, our analysis yielded 79,228,354, 72,336,470, 81,859,826, 77,649,400, 77,194,276, and 75,697,016 clean reads with a mean length of 150 bp from the control and test groups. After deltamethrin treatment, a total of 160 and 167 genes were significantly upregulated and downregulated, respectively. Gene ontology terms "biological process," "cellular component," and "molecular function" were enriched with respect to cell killing, cellular process, other organism part, cell part, binding, and catalytic. Pathway analysis using the Kyoto Encyclopedia of Genes and Genomes showed that the metabolic pathways were significantly enriched. We found that the CYP450 enzyme system, carboxylesterase, glutathione-S-transferase, and material (including carbohydrate, lipid, protein, and other substances) metabolism played important roles in the metabolism of deltamethrin in the hepatopancreas of E. sinensis. This study revealed differentially expressed genes related to insecticide metabolism and detoxification in E. sinensis for the first time and will help in understanding the toxicity and molecular metabolic mechanisms of deltamethrin in E. sinensis.

Fig 1. Effects of deltamethrin treatment on the gene expression profile of E. sinensis.

Volcanic plot of the degree of differences in the expression profile of E. sinensis. X-axis, log₂ (fold change); Y-axis, -log₂ (p-value). Red, significantly upregulated genes; green, significantly downregulated genes. Each dot represents one gene.

Fig 2. Effects of deltamethrin treatment on the gene expression profile using pattern clustering.

Red, upregulated genes; green, downregulated genes. Each line represents one gene.

Fig 3. Histogram of the enriched subcategories after gene ontology (GO) annotation of the differentially expressed genes (DEGs) in E. sinensis specimens that received deltamethrin treatment.

The GO terms (X-axis) were grouped into 3 main ontologies: biological process (BP), cellular component (CC), and molecular function (MF). The Y-axis indicates the number of DEGs.

Fig 4. Histogram of the top 20 most-enriched KEGG pathways of DEGs in E. sinensis after deltamethrin treatment.

Y-axis, KEGG pathway categories; X-axis, statistical significance of the enrichment.

Fig 5. Comparison of 15 gene expression levels by using RNA-Seq and RT-PCR.

Negative values indicate that the gene expression in E. sinensis was downregulated after deltamethrin treatment; positive values indicate that the gene expression was upregulated.