Odor response adaptation in Drosophila—a continuous individualization process

Garg

et al. 2022

Preprint

Maxillary palps, in addition to the antennae, are major olfactory organs in mosquitoes and play an important role in the detection of human hosts. The sensory neurons of the maxillary palps reside in the capitate peg sensilla, each of which contains three neurons. In Aedes aegypti, the neuron with the largest spike amplitude in the sensillum is known to detect carbon dioxide. However, the responses of the other two neurons and the functional consequences of the grouping of these neurons within sensilla are not well understood. Here we identify odorants that activate the other two neurons. We detect a short-term plasticity in the odor-evoked local field potential of the sensillum and show that it originates in the spiking responses of the smallest-amplitude neuron, even though all three neurons contribute to the local field potential. We also detect inhibitory interactions among these neurons within the sensillum. We further show that the plasticity and the lateral interactions are functionally important as they affect the responses of the downstream projection neurons in the antennal lobe.

Section: Discussionmentioning

confidence: 56%

Plasticity and interactions in the odor responses of maxillary palps neurons in Aedes aegypti

Garg

et al. 2022

Preprint

“…Furthermore, the important sensory and perceptual properties of neuronal sensitization and de-sensitization (adaptation) in the context of repeated odor stimulation are thought to be underpinned by metabotropic activity within OSNs (Murmu et al, 2011 ; Guo et al, 2017 ; Jafari and Alenius, 2021 ). For instance, repeated sub-detection threshold of odor stimulations produces stronger responses in the antennal sensilla of live flies (Getahun et al, 2013 ), as well as in a CHO cell line expressing D. melanogaster ORs (Mukunda et al, 2016 ).…”

Section: Introductionmentioning

confidence: 99%

Modulation of the NO-cGMP pathway has no effect on olfactory responses in the Drosophila antenna

Prelic

Getahun

Kaltofen

et al. 2023

Front. Cell. Neurosci.

Olfaction is a crucial sensory modality in insects and is underpinned by odor-sensitive sensory neurons expressing odorant receptors that function in the dendrites as odorant-gated ion channels. Along with expression, trafficking, and receptor complexing, the regulation of odorant receptor function is paramount to ensure the extraordinary sensory abilities of insects. However, the full extent of regulation of sensory neuron activity remains to be elucidated. For instance, our understanding of the intracellular effectors that mediate signaling pathways within antennal cells is incomplete within the context of olfaction in vivo. Here, with the use of optical and electrophysiological techniques in live antennal tissue, we investigate whether nitric oxide signaling occurs in the sensory periphery of Drosophila. To answer this, we first query antennal transcriptomic datasets to demonstrate the presence of nitric oxide signaling machinery in antennal tissue. Next, by applying various modulators of the NO-cGMP pathway in open antennal preparations, we show that olfactory responses are unaffected by a wide panel of NO-cGMP pathway inhibitors and activators over short and long timescales. We further examine the action of cAMP and cGMP, cyclic nucleotides previously linked to olfactory processes as intracellular potentiators of receptor functioning, and find that both long-term and short-term applications or microinjections of cGMP have no effect on olfactory responses in vivo as measured by calcium imaging and single sensillum recording. The absence of the effect of cGMP is shown in contrast to cAMP, which elicits increased responses when perfused shortly before olfactory responses in OSNs. Taken together, the apparent absence of nitric oxide signaling in olfactory neurons indicates that this gaseous messenger may play no role as a regulator of olfactory transduction in insects, though may play other physiological roles at the sensory periphery of the antenna.

“…The mechanism driving this mRNA modulation caused by prolonged odor exposure is not well understood; it has been suggested to be a form of olfactory sensory adaptation and likely a ubiquitous feature of ORNs [ 16 , 17 ]. Since neurons need to respond to changes in chemosensory cues by reducing noise while remaining dynamically responsive to new and salient cues, modulation at the transcription level could potentially be an evolutionary response to sustained noise [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Odor-evoked transcriptomics of Aedes aegypti mosquitoes

Mappin,

Bellantuono,

Ebrahimi

et al. 2023

PLoS ONE

Modulation of odorant receptors mRNA induced by prolonged odor exposure is highly correlated with ligand-receptor interactions in Drosophila as well as mammals of the Muridae family. If this response feature is conserved in other organisms, this presents an intriguing initial screening tool when searching for novel receptor-ligand interactions in species with predominantly orphan olfactory receptors. We demonstrate that mRNA modulation in response to 1-octen-3-ol odor exposure occurs in a time- and concentration-dependent manner in Aedes aegypti mosquitoes. To investigate gene expression patterns at a global level, we generated an odor-evoked transcriptome associated with 1-octen-3-ol odor exposure. Transcriptomic data revealed that ORs and OBPs were transcriptionally responsive whereas other chemosensory gene families showed little to no differential expression. Alongside chemosensory gene expression changes, transcriptomic analysis found that prolonged exposure to 1-octen-3-ol modulated xenobiotic response genes, primarily members of the cytochrome P450, insect cuticle proteins, and glucuronosyltransferases families. Together, these findings suggest that mRNA transcriptional modulation of olfactory receptors caused by prolonged odor exposure is pervasive across taxa and can be accompanied by the activation of xenobiotic responses.