Olfactory circuits and behaviors of nematodes

Rengarajan, Sophie; Hallem, Elissa A.

doi:10.1016/j.conb.2016.09.002

Cited by 53 publications

(52 citation statements)

References 95 publications

(218 reference statements)

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“…This nematode is adapted to a life feeding on bacteria in rotting fruit (17). It has sensory receptors for odors, tastants, pheromones, and respiratory gases, as well as temperature, mechanical, and noxious cues (18)(19)(20)(21). Despite this simplicity, the mechanisms by which its nervous system marshals information about past and present sensory experience to shape behavioral priorities remain largely mysterious.…”

mentioning

confidence: 99%

Memory of recent oxygen experience switches pheromone valence in Caenorhabditis elegans

Fenk

Bono

2017

Proc. Natl. Acad. Sci. U.S.A.

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Animals adjust their behavioral priorities according to momentary needs and prior experience. We show that Caenorhabditis elegans changes how it processes sensory information according to the oxygen environment it experienced recently. C. elegans acclimated to 7% O 2 are aroused by CO 2 and repelled by pheromones that attract animals acclimated to 21% O 2 . This behavioral plasticity arises from prolonged activity differences in a circuit that continuously signals O 2 levels. A sustained change in the activity of O 2 -sensing neurons reprograms the properties of their postsynaptic partners, the RMG hub interneurons. RMG is gap-junctionally coupled to the ASK and ADL pheromone sensors that respectively drive pheromone attraction and repulsion. Prior O 2 experience has opposite effects on the pheromone responsiveness of these neurons. These circuit changes provide a physiological correlate of altered pheromone valence. Our results suggest C. elegans stores a memory of recent O 2 experience in the RMG circuit and illustrate how a circuit is flexibly sculpted to guide behavioral decisions in a context-dependent manner.neural circuit | experience-dependent plasticity | tonic circuit | oxygen sensing | acclimation T he body comprises multiple highly integrated subsystems working together to sustain life from moment to moment and over long time scales (1). Much of this coordination involves dynamically interacting neural circuits that optimize responses to current circumstances by taking into account sensory input, organismal state, and previous experience (2-8). Circuit cross-talk enables animals to adjust their behavioral priorities to changing environments, e.g., variation in temperature, humidity, day length, or oxygen (O 2 ) levels (9-13). Whereas some behavioral adjustments can be rapid (14, 15), others develop over time, as animals adapt to changed conditions. How animals store information about their recent environment, and use this information to modify behavioral choices, is poorly understood.The compact nervous system of Caenorhabditis elegans, which comprises only 302 uniquely identifiable neurons (wormwiring.org) (16), provides an opportunity to study the links between prior environmental experience, circuit plasticity, and behavioral change. This nematode is adapted to a life feeding on bacteria in rotting fruit (17). It has sensory receptors for odors, tastants, pheromones, and respiratory gases, as well as temperature, mechanical, and noxious cues (18-21). Despite this simplicity, the mechanisms by which its nervous system marshals information about past and present sensory experience to shape behavioral priorities remain largely mysterious. The anatomical connectome, while valuable (22), is insufficient to explain or predict neuronal network function (23, 24), partly because neuromodulators can dynamically reconfigure and specify functional circuits (25-27).When ambient O 2 approaches 21%, C. elegans wild isolates become persistently aroused and burrow to escape the surface (28)(29)(30). This state swi...

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confidence: 99%

Memory of recent oxygen experience switches pheromone valence in Caenorhabditis elegans

Fenk

Bono

2017

Proc. Natl. Acad. Sci. U.S.A.

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“…However, because sensory neuroanatomy is generally conserved across nematode species, the positional analogs of the C. elegans AWA, AWB, and AWC olfactory neurons are likely to mediate olfactory behaviors in parasitic nematodes (Gang and Hallem 2016; Rengarajan and Hallem 2016). Differences in olfactory behavior across species may arise from species-specific differences in the functional properties of olfactory microcircuit neurons and/or the wiring of these neurons.…”

Section: Discussionmentioning

confidence: 99%

Olfactory Preferences of the Parasitic Nematode Howardula aoronymphium and its Insect Host Drosophila falleni

et al. 2017

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Many parasitic nematodes have an environmental infective stage that searches for hosts. Olfaction plays an important role in this process, with nematodes navigating their environment using host-emitted and environmental olfactory cues. The interactions between parasitic nematodes and their hosts are also influenced by the olfactory behaviors of the host, since host olfactory preferences drive behaviors that may facilitate or impede parasitic infection. However, how olfaction shapes parasite-host interactions is poorly understood. Here we investigated this question using the insect-parasitic nematode Howardula aoronymphium and its host, the mushroom fly Drosophila falleni. We found that both H. aoronymphium and D. falleni are attracted to mushroom odor and a subset of mushroom-derived odorants, but they have divergent olfactory preferences that are tuned to different mushroom odorants despite their shared mushroom environment. H. aoronymphium and D. falleni respond more narrowly to odorants than Caenorhabditis elegans and Drosophila melanogaster, consistent with their more specialized niches. Infection of D. falleni with H. aoronymphium alters its olfactory preferences, rendering it more narrowly tuned to mushroom odor. Our results establish H. aoronymphium-D. falleni as a model system for studying olfaction in the context of parasite-host interactions.

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“…化学感受器是PPNs非常重要的感觉器官, 它参与了PPNs在土壤中的迁移、响应宿主发出的化学信号以及在宿主中寻找合适的摄食点等多个过程 [8] . PPNs 与模式线虫秀丽隐杆线虫(Caenorhabditis elegans)共享保守的神经解剖学位置 [9] , C. elegans通过化学感应神经元感知化学物质, 化学感应神经元主要包括头部感受器(amphid)、尾部感受器(phasmid)和内阴唇神经元. 它们穿透角质层以将其感觉纤毛暴露于环境中 [10] .…”

Section: 化感神经元种类、结构与定位unclassified