Heme-Peroxidase 2, a Peroxinectin-Like Gene, Regulates Bacterial Homeostasis in Anopheles stephensi Midgut.

Parik Kakani,Sanjeev Kumar,Lalita Gupta

doi:10.3389/fphys.2020.572340

Abstract

The dynamic nature of mosquito gut microbiome is associated with different stages of development and feeding behaviors. Therefore, mosquito gut harbors a wide range of endogenous microbes that promote numerous life processes such as, nutrition, reproduction and immunity. In addition, gut microbiota also play an important role in the regulation of Plasmodium (malaria parasite) development. Thus, understanding the mechanism of microbial homeostasis in mosquito gut might be one of the strategies to manipulate malaria parasite development. In the present study, we characterized a 692 amino acids long secreted midgut heme-peroxidase 2 (AsHPX2) in Anopheles stephensi, the major Indian malaria vector. The presence of putative integrin binding motifs, LDV (Leu–Asp–Val), indicated its peroxinectin-like nature. Our phylogenetic analysis revealed that AsHPX2 is a Culicinae lineage-specific gene. RNA interference (RNAi)-mediated silencing of AsHPX2 gene significantly enhanced the growth of midgut bacteria in sugar-fed mosquitoes against sham-treated controls. Interestingly, blood-feeding drastically reduced AsHPX2 gene expression and enhanced the growth of midgut bacteria. These results revealed a negative correlation between the expression of AsHPX2 gene and gut bacterial growth. We proposed that AsHPX2, being a mosquito-specific gene, might serve as a “potent target” to manipulate midgut microbiota and vector competence.

Highlights

Emerged mosquitoes are born with a limited energy reserve and they start feeding the nectar to replenish energy in order to power the flight for swarming, mating and blood-seeking activities
Putative acids long secreted midgut heme-peroxidase 2 (AsHPX2) gene was identified in contig 7,145 of unannotated An. stephensi genome as described in the Materials and Methods
The 5 upstream region of AsHPX2 gene was analyzed by JASPAR and MatInspector software to identify putative transcription factor binding motifs (TFBM) in its promoter region

Summary

Introduction

Emerged mosquitoes are born with a limited energy reserve and they start feeding the nectar to replenish energy in order to power the flight for swarming, mating and blood-seeking activities. The initial feeding behavior contributes to the establishment of the microbial community in the mosquito midgut. The midgut microbes facilitate food digestion, metabolism, detoxification and the development of immunity (Gusmão et al, 2007; Minard et al, 2013; Kajla et al, 2015). The dynamic nature of gut microbiota is associated with different stages of mosquito development as well as their nutritional conditions. AsHPX2 Maintains Midgut Bacterial Homeostasis midguts cellulose degrading bacteria predominate, the bacteria facilitating blood digestion are more common in blood-fed midguts (de Gaio et al, 2011; Wang et al, 2011; Minard et al, 2013). The microbial interaction with mosquito midgut immunity plays a pivotal role in the biological outcome of this symbiotic association. Microbial homeostasis is managed by numerous immune mechanisms such as the production of lysozyme, reactive oxygen species (ROS), reactive nitrogen species (RNS), and antimicrobial peptides (AMPs) (Luckhart et al, 1998; Graca-Souza et al, 2006; Peterson and Luckhart, 2006; Brennan et al, 2008; Nishikori et al, 2009; Login et al, 2011; Wang et al, 2011)

Methods

Results

Conclusion