Molecular basis of odor coding in the malaria vector mosquito Anopheles gambiae

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251

293

In insects, odor cues are discriminated through a divergent family of odorant receptors (ORs). A functional OR complex consists of both a conventional odorant-binding OR and a nonconventional coreceptor (Orco) that is highly conserved across insect taxa. Recent reports have characterized insect ORs as ion channels, but the precise mechanism of signaling remains unclear. We report the identification and characterization of an Orco family agonist, VUAA1, using the Anopheles gambiae coreceptor (AgOrco) and other orthologues. These studies reveal that the Orco family can form functional ion channels in the absence of an odor-binding OR, and in addition, demonstrate a first-in-class agonist to further research in insect OR signaling. In light of the extraordinary conservation and widespread expression of the Orco family, VUAA1 represents a powerful new family of compounds that can be used to disrupt the destructive behaviors of nuisance insects, agricultural pests, and disease vectors alike.

Section: Functional Agonism Of Insect Odorant Receptor Ion Channelsmentioning

confidence: 99%

Functional agonism of insect odorant receptor ion channels

Jones

Pask

Rinker

et al. 2011

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251

293

“…Currently, more than 50 insect odorant receptors have been analyzed using Xenopus oocytes (29), and engineered olfactory receptors for chemical sensing systems are widely studied (10). These receptors can be essentially applied to our proposed device to detect various chemicals.…”

Section: Fig 3 (A)mentioning

confidence: 99%

Highly sensitive and selective odorant sensor using living cells expressing insect olfactory receptors

Misawa

Mitsuno

Kanzaki

et al. 2010

110

This paper describes a highly sensitive and selective chemical sensor using living cells (Xenopus laevis oocytes) within a portable fluidic device. We constructed an odorant sensor whose sensitivity is a few parts per billion in solution and can simultaneously distinguish different types of chemicals that have only a slight difference in double bond isomerism or functional group such as ─OH, ─CHO and ─Cð═OÞ─. We developed a semiautomatic method to install cells to the fluidic device and achieved stable and reproducible odorant sensing. In addition, we found that the sensor worked for multiple-target chemicals and can be integrated with a robotic system without any noise reduction systems. Our developed sensor is compact and easy to replace in the system. We believe that the sensor can potentially be incorporated into a portable system for monitoring environmental and physical conditions. fluidic channel | odorant receptor | robot | Xenopus oocyte

“…We therefore speculated that a subset of the known AgOr ligands (15,16) would also activate flagella, mimicking the effect of Orco agonists. To examine this, we used a panel of odorant ligands in the spermatozoa flagella bioassay, revealing that fenchone, which can activate several AgOrs, including the testes-expressed AgOr11 (15,16), induced significant spermatozoa movements in a concentration-dependent manner (Fig. 3C).…”

Section: Significancementioning

confidence: 99%

“…Although their exact stoichiometry remains unresolved, OR channels serve as nonspecific channels of monovalent and divalent cations, including calcium, whose relative permeabilities depend upon ORx (9). Within this paradigm, ligands for numerous members of the Anopheles gambiae OR family (AgOrs) have been identified (4,(15)(16)(17). Although AgOrs are expressed in tissues beyond adult head appendages, studies regarding AgOr function in nonolfactory tissues have not, until now, been conducted.…”

mentioning

confidence: 99%

Odorant receptor-mediated sperm activation in disease vector mosquitoes

Pitts

Liu

Zhou

et al. 2014

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Insects, such as the malaria vector mosquito, Anopheles gambiae, depend upon chemoreceptors to respond to volatiles emitted from a range of environmental sources, most notably blood meal hosts and oviposition sites. A subset of peripheral signaling pathways involved in these insect chemosensory-dependent behaviors requires the activity of heteromeric odorant receptor (OR) ion channel complexes and ligands for numerous A. gambiae ORs (AgOrs) have been identified. Although AgOrs are expressed in nonhead appendages, studies characterizing potential AgOr function in nonolfactory tissues have not been conducted. In the present study, we explore the possibility that AgOrs mediate responses of spermatozoa to endogenous signaling molecules in A. gambiae. In addition to finding AgOr transcript expression in testes, we show that the OR coreceptor, AgOrco, is localized to the flagella of A. gambiae spermatozoa where Orco-specific agonists, antagonists, and other odorant ligands robustly activate flagella beating in an Orco-dependent process. We also demonstrate Orco expression and Orco-mediated activation of spermatozoa in the yellow fever mosquito, Aedes aegypti. Moreover, we find Orco localization in testes across distinct insect taxa and posit that OR-mediated responses in spermatozoa may represent a general characteristic of insect reproduction and an example of convergent evolution.transcriptomics | cell signaling | gamete | chemical ecology | Culicidae