Reactive oxygen species-producing genes regulate mosquito midgut bacteria colonization, transcriptomic changes and...

The mosquito midgut uses ROS (Reactive Oxygen Species)-producing pathway to control midgut bacteria and maintain cell regeneration. However, it is not clear what are the functional and mechanistic differences between the two components, NOX (NADPH oxidase) and DUOX (Dual Oxidase) enzymes. In this study, we characterize the different roles of Nox and Duox gene in eliminating ECC15 (Erwinia carotovora 15) after oral infection and controlling the microbiome by counting CFU (Colony-forming unit) and 16S rRNA sequencing after RNA interference-mediated knockdown. We also determined the different transcriptomic changes by RNA-sequencing and cell regeneration by immunostaining after knocking down the genes upon ECC15 infection. Here, we report that Nox but not Duox was necessary for eliminating ECC15 and suppressed more rare species in the microbiome. Transcriptionally, we found that Nox controls more gene responses than Duox upon ECC15 infection; the heat shock protein pathway may be the main stress pathway induced by ECC15 that discriminates Nox (highly-related) and Duox. The MAPK pathway was robustly induced in control (LacZ) and Duox-knockdown mosquitoes, but not in Nox-knockdown mosquitoes. AMP gene induction was also suppressed only in Nox-knockdown mosquitoes. We also found that ECC15 infection induced strong cell regeneration, while Nox RNAi suppressed it strongly. Although, Duox was highly related to metalloexopeptidase activity genes comparing to Nox.