Prokaryotic Expression of dsRNA Based on the mapk-like Gene Related to Immune Response of Aedes aegypti and the Changes in Expression Levels After Feeding
Abstract：Mapk-like, the signaling transduction related mitogen-activated protein kinase gene, shares a conserve motif with p38 MAPK that involves in cellular defense of Caenorhabditis elegans against Bacillus thuringiensis(Bt) Cry toxins. Little validation work, however, had been done in its important role for defense response of Aedes aegypti to Cry toxins. Therefore, RNaseⅢ-absent Escherichia coli HT115, with the high-efficiency and low-cost, was applied to establish a convenient and economical method for mass production of dsRNA for RNA silencing. Using specific primers, mapk-like gene (GenBank No. AAEL003728-RA) was amplified. Then 361 bp PCR products were cloned into the cloning vector pMD18-T and subcloned into the expression vector pLitmus28i, which contained 2 T7 promoters located in each side of multiple cloning sites with the digestion of restriction endonuclease XbaⅠ/XhoⅠ. The recombinant plasmid pLitmus28i-mapk-like was transformed into the HT115. dsRNAs of 1.18 μg/mL of bacteria liquid with high quality were obtained after 0.5 mmol/L IPTG induction. In addition, nanoparticles were prepared by mixing resulted dsRNA and chitosan and the supernatant was examined by agarose gel electrophoresis. These results indicated a good coagulation effect for chitosan, by which nanoparticles could protect dsRNA from dissociation from the mixture of feed andagarose and the stability was improved. Finally, the relative expression levels of mapk-like gene after the effective dsRNA feeding decreased to 65%. These results provide potential for use in RNAi, screening for more defense related gene, and basic research for RNA silencing to control mosquito transmitted diseases.
