Live calcium imaging ofAedes aegyptineuronal tissues reveals differential importance of chemosensory systems for life-history-specific foraging strategies

Abstract

Aedes aegypti have a wide variety of sensory pathways that have supported success as a species as well as a highly competent vector of numerous debilitating infectious pathogens. Investigations into mosquito sensory systems and their effects on behavior are valuable resources for the advancement of mosquito control strategies. Numerous studies have elucidated key 1 . CC-BY-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/345389 doi: bioRxiv preprint first posted online Jun. 12, 2018; aspects of mosquito sensory systems, however there remains critical gaps within the field. In particular, compared to that of the adult form, there has been a lack of studies directed towards the immature life stages. Additionally, although numerous studies have pinpointed specific sensory receptors as well as relevant response behaviors, there has been a lack of studies able to monitor both concurrently. To begin filling aforementioned gaps, here we engineered Ae. aegypti to ubiquitously express a genetically encoded calcium indicator, GCaMP6s. Using this strain, combined with advanced confocal microscopy, we were able to simultaneously measure live stimulus-evoked calcium responses in both neuronal and muscle cells with a wide spatial range and resolution. Moreover, by coupling in vivo calcium imaging with behavioral assays we were able to gain functional insights into how stimulus-evoked neural and muscle activities are represented, modulated, and transformed in mosquito larvae enabling us to elucidate mosquito sensorimotor properties important for life-history-specific foraging strategies. Significance StatementUnderstanding mosquito sensory systems and resulting behavior has been a major factor in the advancement of mosquito control innovations. Aedes aegypti larvae offer an effective life stage for further elucidating information on mosquito sensory systems. Due to their relatively simplified nervous system, mosquito larvae are ideal for studying neural signal transduction, coding, and behavior. Moreover, a better understanding of the larval sensory system may enable the development of novel control methodologies able to target mosquitoes before they reach a vector-competent stage. Here we engineer Ae. aegypti to ubiquitously express a genetically encoded calcium indicator, GCaMP6s and use this tool to observe links between sensorimotor responses and behavior by exploiting live calcium imaging as well as live tracking based behavioral assays. Main Text IntroductionThe yellow fever mosquito, Aedes aegypti , is a global vector of numerous debilitating arboviruses including Chikungunya, Dengue, Yellow Fever, and Zika [1] . Due to its ability to transmit copious pathogens, adaptability to diverse climates, flexibility in oviposition sites, and desiccation-tolerant eggs, Ae. aegypti are significant worldwide epidemiological...

The ion channel ppk301 controls freshwater egg-laying in the mosquito Aedes aegypti

“…ppk301-T2A-QF2 was generated through CRISPR-mediated homologous recombination into the endogenous locus. We initially attempted to use constructs with gene-specific promoter fragments to drive transgenic constructs, including the broadly expressed polyubitiquin promoter (Anderson et al, 2010), but these either did not express at all or were expressed sporadically and mostly in non-neuronal cells (Bui et al, 2018). We also had no success with the Gal4/UAS (Brand and Perrimon, 1993) system in Ae.…”

Geosmin attractsAedes aegyptimosquitoes to oviposition sites

“…To address this issue, we next turned to functional imaging, using an Ae. aegypti knock-in strain (PUb-GCaMP6s) carrying pan-neural expression of the calcium sensitive reporter GCaMP6s from the ubiquitin locus [Bui et al, 2018]. PUb-GCaMP6s mosquitoes were glued to holders that permitted two-photon imaging of calcium responses in the antennal lobe (AL) [Vinauger et al, 2018] (Figure 3B, C).…”