Blood meal-induced changes to antennal transcriptome profiles reveal shifts in odor sensitivities in Anopheles gambiae

Abstract

Olfactory-driven behaviors are central to the lifecycle of the malaria vector mosquito Anopheles gambiae and are initiated by peripheral signaling in the antenna and other olfactory tissues. To continue gaining insight into the relationship between gene expression and olfaction, we have performed cohort comparisons of antennal transcript abundances at five time points after a blood meal, a key event in both reproduction and disease transmission cycles. We found that more than 5,000 transcripts displayed significant abundance differences, many of which were correlated by cluster analysis. Within the chemosensory gene families, we observed a general reduction in the level of chemosensory gene transcripts, although a subset of odorant receptors (AgOrs) was modestly enhanced in post-bloodfed samples. Integration of AgOr transcript abundance data with previously characterized AgOr excitatory odorant response profiles revealed potential changes in antennal odorant receptivity that coincided with the shift from host-seeking to oviposition behaviors in blood-fed female mosquitoes. Behavioral testing of ovipositing females to odorants highlighted by this synthetic analysis identified two unique, unitary oviposition cues for An. gambiae, 2-propylphenol and 4-methylcyclohexanol. We posit that modest, yet cumulative, alterations of AgOr transcript levels modulate peripheral odor coding resulting in biologically relevant behavioral effects. Moreover, these results demonstrate that highly quantitative, RNAseq transcript abundance data can be successfully integrated with functional data to generate testable hypotheses.chemoreceptor | bioinformatics | transcriptomics

CCAP and FMRFamide-like peptides accelerate the contraction rate of the antennal accessory pulsatile organs (auxiliary hearts) of mosquitoes

“…Moreover, antennal receptor neurons located within the sensilla of the flagellum detect odorant and thermal cues, which modulate hostseeking (i.e. blood feeding) and oviposition (Wang et al, 2009;Rinker et al, 2013;Suh et al, 2016). Because of the critical role they play in survival and reproduction, mosquitoes must ensure that molecules required for proper antennal functioning are efficiently transported into and out of these appendages.…”

Hemolymph circulation in insect sensory appendages: functional mechanics of antennal accessory pulsatile organs (auxiliary hearts) in the mosquitoAnopheles gambiae

“…The antennae also mechanically assist during the mating of fleas, and contain the timing elements of the sun compass that drives the autumn migration of monarch butterflies (Hsu and Wu, 2001;Merlin et al, 2009). In mosquitoes, the detection of near-field sound by the antennae's Johnston's organs influences courtship and mating, and the reception of odorant and thermal cues by antennal receptor neurons controls oviposition and host-seeking behaviors (Cator et al, 2009;Wang et al, 2009;Carey et al, 2010;Rinker et al, 2013). Because antennae are intricately involved in essential physiological processes, insects must ensure that molecules required for proper…”

Odorant receptor-mediated sperm activation in disease vector mosquitoes

“…transcriptomics | cell signaling | gamete | chemical ecology | Culicidae T o date, studies of odorant receptor (OR) expression and function in mosquitoes and other insects have been limited to adult and larval appendages where the fundamental properties of insect chemosensation continue to be elucidated (1)(2)(3)(4)(5)(6). Unlike their mammalian counterparts, which function strictly as G protein-coupled receptors (GPCRs), insect ORs generally act as heteromeric ion channels of at least two subunits: a highly conserved coreceptor (Orco) and a ligand-recognizing receptor (ORx) (7)(8)(9)(10)(11), although evidence for second messenger signaling has also been observed (12,13), especially in sex pheromone signaling (14).…”