MOLECULAR ANALYSIS OF NEURO-OLFACTORY SYSTEM OF INDIAN MALARIAL VECTOR ANOPHELES CULICIFACIES

Abstract

Mosquitoes are the deadliest animals in the world and responsible for transmitting a variety of infectious disease such as malaria, dengue fever, chikungunya, zika fever. Among them, malaria which is transmitted by Anopheles mosquitoes is one of the major vector-borne diseases that cause millions of mortality and morbidity worldwide. Continuous climate change, global warming, and other environmental factors are the facilitators of mosquito population growth and thus worse the situation of mosquitoborne diseases. Current tools to control and manage malaria face challenges due to the emergence of parasite resistance to antimalarial drugs and insecticide resistance of mosquitoes. Thus, alternative approaches are needed for the global elimination of malaria. Evolution and adaptation of blood feeding behavior of adult female mosquitoes not only favored their reproductive success but also make them an important disease vectors. Mosquitoes rely extensively on their sense of smell (olfaction) for the majority of their lifecycle stages and the well-developed nasal system plays an essential role in the facilitation of olfactory guided behavior. Thus, decoding the genetic relationship of the neuro-olfactory system managing host seeking and blood feeding behavioral responses of adult female mosquitoes, may provide an opportunity to design new molecular strategy to disrupt human-mosquito interactions. Our RNA-Seq analysis of the neuro-olfactory system of Anopheles culicifacies mosquito, which transmit more than 65% malaria cases in rural India, unravelled that a tight coordination of the olfactory and the central nervous system is necessary to regulate the ‘pre and post’ blood meal associated with complex behavioral responses such as host-seeking, blood feeding, and oviposition. A comprehensive molecular cataloging and comparative gene expression analysis of the olfactory tissue transcriptome data indicated that synergetic actions of the olfactory encoded molecular factors (Odorants Binding Proteins and Olfactory receptors) facilitate and manage the complex host-seeking behavioral events. Next, transcriptional profiling of the selected olfactory transcripts in two consecutive blood feeding experiment highlighted that adult female mosquitoes might learn and memorize from the priming effect of the first blood meal exposure, which further facilitates host selection and rapid blood meal uptake during second blood feeding event. Furthermore, species-specific transcriptional profiling and an in-silico analysis of novel ‘sensory appendages proteins’ revealed their potential role in host-seeking and blood feeding behavior, possibly a unique target for functional characterization and designing of molecular strategy for the control of An. culicifacies mosquitoes. Our comparative vi

RNA-Seq analysis of naïve and blood fed adult female mosquitoes brain unraveled that a gradual modulation of brain transcripts expression is crucial to regulate the complex events linked to metabolic switch activities such as blood meal digestion, egg maturation, oviposition etc. Finally, the characterization of two olfactory-specific proteins Quick-to-Court and Attractin provide a new knowledge that how mosquitoes manage the conflicting demand of mating vs. blood feeding.