A Chemoreceptor That Detects Molecular Carbon Dioxide

Smith, Ewan St. John; Martínez-Velázquez, Luis A.; Ringstad, Niels

doi:10.1074/jbc.m113.517367

Cited by 51 publications

(62 citation statements)

References 43 publications

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“…We did not find any differences between the animals in different growth mediums, both under normal air conditions and after exposure to 10% CO 2 , which suggests that the effect on the pumping is probably not mediated by changes in pH (Figure S1B). This conclusion is supported by a recent finding that activation of CO 2 -responsive neurons can occur independently of changes in extracellular or intracellular acidosis [25]. In addition, mutations in the carbonic anhydrase genes ( cah-2 , cah-5 , and cah-6 ), which catalyze the conversion of CO 2 into bicarbonate, had no effect on the pumping rate (Figure S1C).…”

Section: Resultssupporting

confidence: 76%

The Response to High CO2 Levels Requires the Neuropeptide Secretion Component HID-1 to Promote Pumping Inhibition

et al. 2014

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Carbon dioxide (CO2) is a key molecule in many biological processes; however, mechanisms by which organisms sense and respond to high CO2 levels remain largely unknown. Here we report that acute CO2 exposure leads to a rapid cessation in the contraction of the pharynx muscles in Caenorhabditis elegans. To uncover the molecular mechanisms underlying this response, we performed a forward genetic screen and found that hid-1, a key component in neuropeptide signaling, regulates this inhibition in muscle contraction. Surprisingly, we found that this hid-1-mediated pathway is independent of any previously known pathways controlling CO2 avoidance and oxygen sensing. In addition, animals with mutations in unc-31 and egl-21 (neuropeptide secretion and maturation components) show impaired inhibition of muscle contraction following acute exposure to high CO2 levels, in further support of our findings. Interestingly, the observed response in the pharynx muscle requires the BAG neurons, which also mediate CO2 avoidance. This novel hid-1-mediated pathway sheds new light on the physiological effects of high CO2 levels on animals at the organism-wide level.

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Section: Resultssupporting

confidence: 76%

The Response to High CO2 Levels Requires the Neuropeptide Secretion Component HID-1 to Promote Pumping Inhibition

et al. 2014

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“…Odorants and pheromones are detected by large families of seven-transmembrane domain G protein-coupled receptors (GPCRs) [68, 72], while the gustatory response requires receptor guanylate cyclases (rGCs) [73]. CO 2 detection is mediated in part by the rGC GCY-9 [74–76]; however, GCY-9-independent mechanisms of CO 2 detection appear to operate in some sensory neurons but have not yet been characterized [77, 78]. O 2 detection is mediated by soluble guanylate cyclases and globins [79–81].…”

Section: The Neural Basis Of Host-seeking Behaviormentioning

confidence: 99%

Mechanisms of host seeking by parasitic nematodes

Gang

Hallem

2016

Molecular and Biochemical Parasitology

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The phylum Nematoda comprises a diverse group of roundworms that includes parasites of vertebrates, invertebrates, and plants. Human-parasitic nematodes infect approximately one billion people worldwide and cause some of the most common neglected tropical diseases, particularly in low-resource countries [1]. Parasitic nematodes of livestock and crops result in billions of dollars in losses each year [1]. Many nematode infections are treatable with low-cost anthelmintic drugs, but repeated infections are common in endemic areas and drug resistance is a growing concern with increasing therapeutic and agricultural administration [1]. Many parasitic nematodes have an environmental infective larval stage that engages in host seeking, a process whereby the infective larvae use sensory cues to search for hosts. Host seeking is a complex behavior that involves multiple sensory modalities, including olfaction, gustation, thermosensation, and humidity sensation. As the initial step of the parasite-host interaction, host seeking could be a powerful target for preventative intervention. However, host-seeking behavior remains poorly understood. Here we review what is currently known about the host-seeking behaviors of different parasitic nematodes, including insect-parasitic nematodes, mammalian-parasitic nematodes, and plant-parasitic nematodes. We also discuss the neural bases of these behaviors.

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“…To do so, we scored the expression of functionally relevant terminal markers of these neurons in animals with or without mir-791. The candidate CO 2 sensor in the BAGs is a receptor guanylate cyclase encoded by gcy-9 (Hallem et al 2011;Smith et al 2013). Upon CO 2 increase, GCY-9 is thought to generate cGMP, opening a cGMP-gated channel formed by the products of tax-2 and tax-4.…”

Section: Resultsmentioning

confidence: 99%

“…Together, it seems that BAGs do not require high levels of CA activity to fulfill their function. This might reflect the fact that while other systems likely sense HCO 3 − or H + , BAGs sense CO 2 directly (Smith et al 2013).…”

Section: Sequences In Thementioning

confidence: 99%

Neuron type-specific miRNA represses two broadly expressed genes to modulate an avoidance behavior in C. elegans

et al. 2016

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Two broad gene classes are distinguished within multicellular organisms: cell type-specific genes, which confer particular cellular properties, and ubiquitous genes that support general cellular functions. However, certain socalled ubiquitous genes show functionally relevant cell type-specific repression. How such repression is achieved is poorly understood. MicroRNAs (miRNAs) are repressors, many of which are expressed with high cell type specificity. Here we show that mir-791, expressed exclusively in the CO 2 -sensing neurons in Caenorhabditis elegans, represses two otherwise broadly expressed genes. This repression is necessary for normal neuronal function and behavior of the animals toward CO 2 . miRNA-mediated repression of broadly transcribed genes is a previously unappreciated strategy for cellular specialization.

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A Chemoreceptor That Detects Molecular Carbon Dioxide

Cited by 51 publications

References 43 publications

The Response to High CO2 Levels Requires the Neuropeptide Secretion Component HID-1 to Promote Pumping Inhibition

The Response to High CO2 Levels Requires the Neuropeptide Secretion Component HID-1 to Promote Pumping Inhibition

Mechanisms of host seeking by parasitic nematodes

Neuron type-specific miRNA represses two broadly expressed genes to modulate an avoidance behavior in C. elegans

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