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Mangalath A, Thekkuveettil A. Olfactory imprinting enhances associative learning and memory in C. elegans. Biochem Biophys Res Commun 2023; 674:109-116. [PMID: 37419031 DOI: 10.1016/j.bbrc.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/01/2023] [Indexed: 07/09/2023]
Abstract
Learning and memory are fundamental processes for an organism's normal physiological function. Learning can occur at any stage of the organism's physiological development. Imprinted memories formed during the early developmental stage, unlike learning and memory, can last a lifetime. It is not clear whether these two types of memories are interlinked. In this study, we investigated whether imprinted memory influences adult learning and memory in a C. elegans model system. We trained the worms for short-term (STAM) and long-term associated memory (LTAM) towards butanone (BT) after conditioning them for imprinted memory towards isoamyl alcohol (IAA). We observed that these worms had improved learning abilities. However, functional imaging revealed that the worms had a long-term depression in the firing pattern in the AIY interneuron, indicating that there were significant changes in neuronal excitation pattern after imprinting, which could explain the enhanced behavioural alterations in animals after imprinting.
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Affiliation(s)
- Aswathy Mangalath
- Division of Molecular Medicine, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, 695012, India
| | - Anoopkumar Thekkuveettil
- Division of Molecular Medicine, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, 695012, India.
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2
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Jiang Y, Huang M, Qin R, Jiang D, Chang D, Xie Y, Li C, Wang C. Full-Length Transcriptome Analysis of Soybean Cyst Nematode ( Heterodera glycines) Reveals an Association of Behaviors in Response to Attractive pH and Salt Solutions with Activation of Transmembrane Receptors, Ion Channels, and Ca 2+ Transporters. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023. [PMID: 37267587 DOI: 10.1021/acs.jafc.3c00908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Soybean cyst nematode (Heterodera glycines Ichinohe), a devastating pathogen in soybean, was chosen as a model system to investigate nematode behavior and gene expression changes in response to acidic and basic pH and salt signals (pH 4.5, 5.25, 8.6, and 10 and NaCl) through full-length transcriptome sequencing of 18 samples. An average of 4.36 Gbp of clean reads per sample were generated, and 3972 novel genes and 29,529 novel transcripts were identified. Sequence structural variation during or after transcription may be associated with the nematode's behavioral response. The functional analysis of 1817/4962 differentially expressed genes/transcripts showed that signal transduction pathways, including transmembrane receptors, ion channels, and Ca2+ transporters, were activated, but pathways involved in nematode development (e.g., ribosome) and energy production (e.g., oxidative phosphorylation) were inhibited. A corresponding model was established. Our findings suggest that these receptors and ion channels might be potential targets for nematicides or drug discovery.
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Affiliation(s)
- Ye Jiang
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Minghui Huang
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
| | - Ruifeng Qin
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Dan Jiang
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Doudou Chang
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yifan Xie
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Chunjie Li
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
| | - Congli Wang
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081 Heilongjiang, P. R. China
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3
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Park SJ, Ja WW. The basics of base sensing. Nat Metab 2023; 5:364-365. [PMID: 36941449 DOI: 10.1038/s42255-023-00763-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Affiliation(s)
- Scarlet J Park
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL, USA
| | - William W Ja
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL, USA.
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4
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Mi T, Mack JO, Koolmees W, Lyon Q, Yochimowitz L, Teng ZQ, Jiang P, Montell C, Zhang YV. Alkaline taste sensation through the alkaliphile chloride channel in Drosophila. Nat Metab 2023; 5:466-480. [PMID: 36941450 PMCID: PMC10665042 DOI: 10.1038/s42255-023-00765-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 02/09/2023] [Indexed: 03/23/2023]
Abstract
The sense of taste is an important sentinel governing what should or should not be ingested by an animal, with high pH sensation playing a critical role in food selection. Here we explore the molecular identities of taste receptors detecting the basic pH of food using Drosophila melanogaster as a model. We identify a chloride channel named alkaliphile (Alka), which is both necessary and sufficient for aversive taste responses to basic food. Alka forms a high-pH-gated chloride channel and is specifically expressed in a subset of gustatory receptor neurons (GRNs). Optogenetic activation of alka-expressing GRNs is sufficient to suppress attractive feeding responses to sucrose. Conversely, inactivation of these GRNs causes severe impairments in the aversion to high pH. Altogether, our discovery of Alka as an alkaline taste receptor lays the groundwork for future research on alkaline taste sensation in other animals.
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Affiliation(s)
- Tingwei Mi
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | - John O Mack
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | | | - Quinn Lyon
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | | | - Zhao-Qian Teng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, China
| | - Peihua Jiang
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | - Craig Montell
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Yali V Zhang
- Monell Chemical Senses Center, Philadelphia, PA, USA.
- Department of Physiology, The Diabetes Research Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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5
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Khan M, Hartmann AH, O’Donnell MP, Piccione M, Pandey A, Chao PH, Dwyer ND, Bargmann CI, Sengupta P. Context-dependent reversal of odorant preference is driven by inversion of the response in a single sensory neuron type. PLoS Biol 2022; 20:e3001677. [PMID: 35696430 PMCID: PMC9232122 DOI: 10.1371/journal.pbio.3001677] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 06/24/2022] [Accepted: 05/16/2022] [Indexed: 11/18/2022] Open
Abstract
The valence and salience of individual odorants are modulated by an animal’s innate preferences, learned associations, and internal state, as well as by the context of odorant presentation. The mechanisms underlying context-dependent flexibility in odor valence are not fully understood. Here, we show that the behavioral response of Caenorhabditis elegans to bacterially produced medium-chain alcohols switches from attraction to avoidance when presented in the background of a subset of additional attractive chemicals. This context-dependent reversal of odorant preference is driven by cell-autonomous inversion of the response to these alcohols in the single AWC olfactory neuron pair. We find that while medium-chain alcohols inhibit the AWC olfactory neurons to drive attraction, these alcohols instead activate AWC to promote avoidance when presented in the background of a second AWC-sensed odorant. We show that these opposing responses are driven via engagement of distinct odorant-directed signal transduction pathways within AWC. Our results indicate that context-dependent recruitment of alternative intracellular signaling pathways within a single sensory neuron type conveys opposite hedonic valences, thereby providing a robust mechanism for odorant encoding and discrimination at the periphery.
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Affiliation(s)
- Munzareen Khan
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Anna H. Hartmann
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Michael P. O’Donnell
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Madeline Piccione
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Anjali Pandey
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Pin-Hao Chao
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Noelle D. Dwyer
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | | | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
- * E-mail:
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6
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Ferkey DM, Sengupta P, L’Etoile ND. Chemosensory signal transduction in Caenorhabditis elegans. Genetics 2021; 217:iyab004. [PMID: 33693646 PMCID: PMC8045692 DOI: 10.1093/genetics/iyab004] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Chemosensory neurons translate perception of external chemical cues, including odorants, tastants, and pheromones, into information that drives attraction or avoidance motor programs. In the laboratory, robust behavioral assays, coupled with powerful genetic, molecular and optical tools, have made Caenorhabditis elegans an ideal experimental system in which to dissect the contributions of individual genes and neurons to ethologically relevant chemosensory behaviors. Here, we review current knowledge of the neurons, signal transduction molecules and regulatory mechanisms that underlie the response of C. elegans to chemicals, including pheromones. The majority of identified molecules and pathways share remarkable homology with sensory mechanisms in other organisms. With the development of new tools and technologies, we anticipate that continued study of chemosensory signal transduction and processing in C. elegans will yield additional new insights into the mechanisms by which this animal is able to detect and discriminate among thousands of chemical cues with a limited sensory neuron repertoire.
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Affiliation(s)
- Denise M Ferkey
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Noelle D L’Etoile
- Department of Cell and Tissue Biology, University of California, San Francisco, CA 94143, USA
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7
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Neuromedin U signaling regulates retrieval of learned salt avoidance in a C. elegans gustatory circuit. Nat Commun 2020; 11:2076. [PMID: 32350283 PMCID: PMC7190830 DOI: 10.1038/s41467-020-15964-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 04/06/2020] [Indexed: 01/07/2023] Open
Abstract
Learning and memory are regulated by neuromodulatory pathways, but the contribution and temporal requirement of most neuromodulators in a learning circuit are unknown. Here we identify the evolutionarily conserved neuromedin U (NMU) neuropeptide family as a regulator of C. elegans gustatory aversive learning. The NMU homolog CAPA-1 and its receptor NMUR-1 are required for the retrieval of learned salt avoidance. Gustatory aversive learning requires the release of CAPA-1 neuropeptides from sensory ASG neurons that respond to salt stimuli in an experience-dependent manner. Optogenetic silencing of CAPA-1 neurons blocks the expression, but not the acquisition, of learned salt avoidance. CAPA-1 signals through NMUR-1 in AFD sensory neurons to modulate two navigational strategies for salt chemotaxis. Aversive conditioning thus recruits NMU signaling to modulate locomotor programs for expressing learned avoidance behavior. Because NMU signaling is conserved across bilaterian animals, our findings incite further research into its function in other learning circuits.
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8
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Multiple sensory neurons mediate starvation-dependent aversive navigation in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2019; 116:18673-18683. [PMID: 31455735 PMCID: PMC6744849 DOI: 10.1073/pnas.1821716116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Processing and integrating multiple sensory inputs are essential for generating appropriate behavioral output, where sensory information of food is particularly important. The soil nematode Caenorhabditis elegans remembers salt concentrations that they have experienced under starvation conditions and learn to avoid them by monitoring current salt concentrations with the salt-sensory neuron called ASER. Here, we described how a sensory neuron pair that was not previously implicated, called ASG, plays a pivotal role in driving food-related navigation; sensory input to these 2 sensory neurons is required for navigation to avoid salt concentrations associated with starvation. Our results show how integrated sensory information determines the bias of turning behaviors to efficiently navigate toward food in starved worms. Animals demonstrate flexible behaviors through associative learning based on their experiences. Deciphering the neural mechanisms for sensing and integrating multiple types of sensory information is critical for understanding such behavioral controls. The soil nematode Caenorhabditis elegans avoids salt concentrations it has previously experienced under starvation conditions. Here, we identify a pair of sensory neurons, the ASG neuron pair, which in cooperation with the ASER salt-sensing neuron generate starvation-dependent salt avoidance. Animals whose sensory input is restricted to only ASER failed to show learned avoidance due to inappropriately directed navigation behaviors. However, their navigation through a salt concentration gradient was improved by allowing sensory inputs to ASG in addition to ASER. Detailed behavioral analyses of these animals revealed that input from ASG neurons is required not only for controlling the frequency of initiating a set of sharp turns (called pirouettes) based on detected ambient salt concentrations but also adjusting the migration direction during pirouettes. Optogenetic activation of ASER by ChR2 induced turning behaviors in a salt concentration-dependent manner where presence of intact ASG was important for the starvation-dependent responses. Calcium imaging of the activity of ASG neurons in freely moving worms revealed that ASG is activated upon turning behavior. Our results indicate that ASG neurons cooperate with the ASER neuron to generate destination-directed reorientation in starvation-associated salt concentration avoidance.
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9
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Shindou T, Ochi-Shindou M, Murayama T, Saita EI, Momohara Y, Wickens JR, Maruyama IN. Active propagation of dendritic electrical signals in C. elegans. Sci Rep 2019; 9:3430. [PMID: 30837592 PMCID: PMC6401061 DOI: 10.1038/s41598-019-40158-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 02/11/2019] [Indexed: 11/09/2022] Open
Abstract
Active propagation of electrical signals in C. elegans neurons requires ion channels capable of regenerating membrane potentials. Here we report regenerative depolarization of a major gustatory sensory neuron, ASEL. Whole-cell patch-clamp recordings in vivo showed supralinear depolarization of ASEL upon current injection. Furthermore, stimulation of animal's nose with NaCl evoked all-or-none membrane depolarization in ASEL. Mutant analysis showed that EGL-19, the α1 subunit of L-type voltage-gated Ca2+ channels, is essential for regenerative depolarization of ASEL. ASEL-specific knock-down of EGL-19 by RNAi demonstrated that EGL-19 functions in C. elegans chemotaxis along an NaCl gradient. These results demonstrate that a natural substance induces regenerative all-or-none electrical signals in dendrites, and that these signals are essential for activation of sensory neurons for chemotaxis. As in other vertebrate and invertebrate nervous systems, active information processing in dendrites occurs in C. elegans, and is necessary for adaptive behavior.
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Affiliation(s)
- Tomomi Shindou
- Neurobiology Research Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan
| | - Mayumi Ochi-Shindou
- Neurobiology Research Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan
| | - Takashi Murayama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan
| | - Ei-Ichiro Saita
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan
| | - Yuto Momohara
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan
| | - Jeffery R Wickens
- Neurobiology Research Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan
| | - Ichiro N Maruyama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan.
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10
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Nematodes avoid and are killed by Bacillus mycoides-produced styrene. J Invertebr Pathol 2018; 159:129-136. [PMID: 30268676 DOI: 10.1016/j.jip.2018.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/21/2018] [Accepted: 09/26/2018] [Indexed: 01/20/2023]
Abstract
Root-knot nematodes are obligate parasites that feed on plant roots and cause serious crop losses worldwide. Bacillus species (Bacilliaceae) can produce nematicidal metabolites and have shown good potential for biological control of nematodes. In this study, Bacillus mycoides strain R2 isolated from rhizosphere soil of tomato plants exhibited high nematicidal activity against the free-living nematode Caenorhabditis elegans and the root-knot nematode Meloidogyne incognita. In a pot experiment, control efficiency of B. mycoides R2 on M. incognita was as high as 90.94%. The nematicidal compound was isolated and identified as styrene. The median lethal concentration of styrene against M. incognita was 4.55 μg/ml (m/v). The volatile styrene caused avoidance and killed nematodes primarily by the olfactory neuron and G protein signal pathway. C. elegans detected styrene with the AWB neuron; the signal was then transmitted to the downstream G protein coupled receptors CHE-3, DOP-3, and STR-2. Then signal activated G protein GPA-3 and GPA-7. The signal was then transmitted to ion channels (CNGs channel and TRPV channel), causing calcium ion internal flow and a stress response towards the increased concentration of intracellular calcium. Styrene should be registered as a nematode repellent and biocontrol agent for protection of crops against root-knot nematode attack.
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11
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Gong Y, Zhu Y, Zou Y, Ma B, Nussinov R, Zhang Q. Human Neuronal Calcium Sensor-1 Protein Avoids Histidine Residues To Decrease pH Sensitivity. J Phys Chem B 2017; 121:508-517. [PMID: 28030949 PMCID: PMC6413881 DOI: 10.1021/acs.jpcb.6b11094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
pH is highly regulated in mammalian central nervous systems. Neuronal calcium sensor-1 (NCS-1) can interact with numerous target proteins. Compared to that in the NCS-1 protein of Caenorhabditis elegans, evolution has avoided the placement of histidine residues at positions 102 and 83 in the NCS-1 protein of humans and Xenopus laevis, possibly to decrease the conformational sensitivity to pH gradients in synaptic processes. We used all-atom molecular dynamics simulations to investigate the effects of amino acid substitutions between species on human NCS-1 by substituting Arg102 and Ser83 for histidine at neutral (R102H and S83H) and acidic pHs (R102Hp and S83Hp). Our cumulative 5 μs simulations revealed that the R102H mutation slightly increases the structural flexibility of loop L2 and the R102Hp mutation decreases protein stability. Community network analysis illustrates that the R102H and S83H mutations weaken the interdomain and strengthen the intradomain communications. Secondary structure contents in the S83H and S83Hp mutants are similar to those in the wild type, whereas the global structural stabilities and salt-bridge probabilities decrease. This study highlights the conformational dynamics effects of the R102H and S83H mutations on the local structural flexibility and global stability of NCS-1, whereas protonated histidine decreases the stability of NCS-1. Thus, histidines at positions 102 and 83 may not be compatible with the function of NCS-1 whether in the neutral or protonated state.
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Affiliation(s)
- Yehong Gong
- College of Physical Education and Training, Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, China
| | - Yuzhen Zhu
- Shanghai Normal University Physical Education College, 100 Gui Lin Road, Shanghai, 200234, China
| | - Yu Zou
- College of Physical Education and Training, Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, China
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, United States
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, United States
- Department of Human Genetics and Molecular Medicine, Sackler Inst. of Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Qingwen Zhang
- College of Physical Education and Training, Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, China
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12
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Mylenko M, Boland S, Penkov S, Sampaio JL, Lombardot B, Vorkel D, Verbavatz JM, Kurzchalia TV. NAD+ Is a Food Component That Promotes Exit from Dauer Diapause in Caenorhabditis elegans. PLoS One 2016; 11:e0167208. [PMID: 27907064 PMCID: PMC5132307 DOI: 10.1371/journal.pone.0167208] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/10/2016] [Indexed: 01/07/2023] Open
Abstract
The free-living soil nematode Caenorhabditis elegans adapts its development to the availability of food. When food is scarce and population density is high, worms enter a developmentally arrested non-feeding diapause stage specialized for long-term survival called the dauer larva. When food becomes available, they exit from the dauer stage, resume growth and reproduction. It has been postulated that compound(s) present in food, referred to as the “food signal”, promote exit from the dauer stage. In this study, we have identified NAD+ as a component of bacterial extract that promotes dauer exit. NAD+, when dissolved in alkaline medium, causes opening of the mouth and ingestion of food. We also show that to initiate exit from the dauer stage in response to NAD+ worms require production of serotonin. Thus, C. elegans can use redox cofactors produced by dietary organisms to sense food.
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Affiliation(s)
- Mykola Mylenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sebastian Boland
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sider Penkov
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Julio L. Sampaio
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Benoit Lombardot
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Daniela Vorkel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Jean-Marc Verbavatz
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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13
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TMC-1 Mediates Alkaline Sensation in C. elegans through Nociceptive Neurons. Neuron 2016; 91:146-54. [PMID: 27321925 DOI: 10.1016/j.neuron.2016.05.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 04/03/2016] [Accepted: 05/04/2016] [Indexed: 11/22/2022]
Abstract
Noxious pH triggers pungent taste and nocifensive behavior. While the mechanisms underlying acidic pH sensation have been extensively characterized, little is known about how animals sense alkaline pH in the environment. TMC genes encode a family of evolutionarily conserved membrane proteins whose functions are largely unknown. Here, we characterize C. elegans TMC-1, which was suggested to form a Na(+)-sensitive channel mediating salt chemosensation. Interestingly, we find that TMC-1 is required for worms to avoid noxious alkaline environment. Alkaline pH evokes an inward current in nociceptive neurons, which is primarily mediated by TMC-1 and to a lesser extent by the TRP channel OSM-9. However, unlike OSM-9, which is sensitive to both acidic and alkaline pH, TMC-1 is only required for alkali-activated current, revealing a specificity for alkaline sensation. Ectopic expression of TMC-1 confers alkaline sensitivity to alkali-insensitive cells. Our results identify an unexpected role for TMCs in alkaline sensation and nociception.
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14
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Epelboin Y, Quintric L, Guévélou E, Boudry P, Pichereau V, Corporeau C. The Kinome of Pacific Oyster Crassostrea gigas, Its Expression during Development and in Response to Environmental Factors. PLoS One 2016; 11:e0155435. [PMID: 27231950 PMCID: PMC4883820 DOI: 10.1371/journal.pone.0155435] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/28/2016] [Indexed: 01/08/2023] Open
Abstract
Oysters play an important role in estuarine and coastal marine habitats, where the majority of humans live. In these ecosystems, environmental degradation is substantial, and oysters must cope with highly dynamic and stressful environmental constraints during their lives in the intertidal zone. The availability of the genome sequence of the Pacific oyster Crassostrea gigas represents a unique opportunity for a comprehensive assessment of the signal transduction pathways that the species has developed to deal with this unique habitat. We performed an in silico analysis to identify, annotate and classify protein kinases in C. gigas, according to their kinase domain taxonomy classification, and compared with kinome already described in other animal species. The C. gigas kinome consists of 371 protein kinases, making it closely related to the sea urchin kinome, which has 353 protein kinases. The absence of gene redundancy in some groups of the C. gigas kinome may simplify functional studies of protein kinases. Through data mining of transcriptomes in C. gigas, we identified part of the kinome which may be central during development and may play a role in response to various environmental factors. Overall, this work contributes to a better understanding of key sensing pathways that may be central for adaptation to a highly dynamic marine environment.
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Affiliation(s)
- Yanouk Epelboin
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l’Environnement Marin, Plouzané, France
| | - Laure Quintric
- Ifremer, Service Ressources Informatiques et Communications, Plouzané, France
| | - Eric Guévélou
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l’Environnement Marin, Plouzané, France
| | - Pierre Boudry
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l’Environnement Marin, Plouzané, France
| | - Vianney Pichereau
- UBO, UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l’Environnement Marin, Plouzané, France
| | - Charlotte Corporeau
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l’Environnement Marin, Plouzané, France
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15
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Maruyama IN. Receptor Guanylyl Cyclases in Sensory Processing. Front Endocrinol (Lausanne) 2016; 7:173. [PMID: 28123378 PMCID: PMC5225109 DOI: 10.3389/fendo.2016.00173] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 12/28/2016] [Indexed: 11/18/2022] Open
Abstract
Invertebrate models have generated many new insights into transmembrane signaling by cell-surface receptors. This review focuses on receptor guanylyl cyclases (rGCs) and describes recent advances in understanding their roles in sensory processing in the nematode, Caenorhabditis elegans. A complete analysis of the C. elegans genome elucidated 27 rGCs, an unusually large number compared with mammalian genomes, which encode 7 rGCs. Most C. elegans rGCs are expressed in sensory neurons and play roles in sensory processing, including gustation, thermosensation, olfaction, and phototransduction, among others. Recent studies have found that by producing a second messenger, guanosine 3',5'-cyclic monophosphate, some rGCs act as direct sensor molecules for ions and temperatures, while others relay signals from G protein-coupled receptors. Interestingly, genetic and biochemical analyses of rGCs provide the first example of an obligate heterodimeric rGC. Based on recent structural studies of rGCs in mammals and other organisms, molecular mechanisms underlying activation of rGCs are also discussed in this review.
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Affiliation(s)
- Ichiro N. Maruyama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- *Correspondence: Ichiro N. Maruyama,
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16
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The Importance of cGMP Signaling in Sensory Cilia for Body Size Regulation in Caenorhabditis elegans. Genetics 2015; 201:1497-510. [PMID: 26434723 DOI: 10.1534/genetics.115.177543] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 10/01/2015] [Indexed: 01/24/2023] Open
Abstract
The body size of Caenorhabditis elegans is thought to be controlled by sensory inputs because many mutants with sensory cilium structure defects exhibit small body size. The EGL-4 cGMP-dependent protein kinase acts in sensory neurons to reduce body size when animals fail to perceive sensory signals. In addition to body size control, EGL-4 regulates various other behavioral and developmental pathways, including those involved in the regulation of egg laying and chemotaxis behavior. Here we have identified gcy-12, which encodes a receptor-type guanylyl cyclase, as a gene involved in the sensory regulation of body size. Analyses with GFP fusion constructs showed that gcy-12 is expressed in several sensory neurons and localizes to sensory cilia. Genetic analyses indicated that GCY-12 acts upstream of EGL-4 in body size control but does not affect other EGL-4 functions. Our studies indicate that the function of the GCY-12 guanylyl cyclase is to provide cGMP to the EGL-4 cGMP-dependent kinase only for limited tasks including body size regulation. We also found that the PDE-2 cyclic nucleotide phosphodiesterase negatively regulates EGL-4 in controlling body size. Thus, the cGMP level is precisely controlled by GCY-12 and PDE-2 to determine body size through EGL-4, and the defects in the sensory cilium structure may disturb the balanced control of the cGMP level. The large number of guanylyl cyclases encoded in the C. elegans genome suggests that EGL-4 exerts pleiotropic effects by partnering with different guanylyl cyclases for different downstream functions.
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17
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Maruyama IN. Activation of transmembrane cell-surface receptors via a common mechanism? The "rotation model". Bioessays 2015; 37:959-67. [PMID: 26241732 PMCID: PMC5054922 DOI: 10.1002/bies.201500041] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
It has long been thought that transmembrane cell-surface receptors, such as receptor tyrosine kinases and cytokine receptors, among others, are activated by ligand binding through ligand-induced dimerization of the receptors. However, there is growing evidence that prior to ligand binding, various transmembrane receptors have a preformed, yet inactive, dimeric structure on the cell surface. Various studies also demonstrate that during transmembrane signaling, ligand binding to the extracellular domain of receptor dimers induces a rotation of transmembrane domains, followed by rearrangement and/or activation of intracellular domains. The paper here describes transmembrane cell-surface receptors that are known or proposed to exist in dimeric form prior to ligand binding, and discusses how these preformed dimers are activated by ligand binding.
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Affiliation(s)
- Ichiro N Maruyama
- Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
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18
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Murayama T, Maruyama IN. Alkaline pH sensor molecules. J Neurosci Res 2015; 93:1623-30. [PMID: 26154399 DOI: 10.1002/jnr.23621] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/12/2015] [Accepted: 06/26/2015] [Indexed: 12/22/2022]
Abstract
Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range.
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Affiliation(s)
- Takashi Murayama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Ichiro N Maruyama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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19
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Zhang H, Shin PKS, Cheung SG. Physiological responses and scope for growth upon medium-term exposure to the combined effects of ocean acidification and temperature in a subtidal scavenger Nassarius conoidalis. MARINE ENVIRONMENTAL RESEARCH 2015; 106:51-60. [PMID: 25771491 DOI: 10.1016/j.marenvres.2015.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 02/23/2015] [Accepted: 03/01/2015] [Indexed: 06/04/2023]
Abstract
Physiological responses (ingestion rate, absorption rate and efficiency, respiration, rate, excretion rate) and scope for growth of a subtidal scavenging gastropod Nassarius conoidalis under the combined effects of ocean acidification (pCO2 levels: 380, 950, 1250 μatm) and temperature (15, 30 °C) were investigated for 31 days. There was a significant reduction in all the physiological rates and scope for growth following short-term exposure (1-3 days) to elevated pCO2 except absorption efficiency at 15 °C and 30 °C, and respiration rate and excretion rate at 15 °C. The percentage change in the physiological rates ranged from 0% to 90% at 15 °C and from 0% to 73% at 30 °C when pCO2 was increased from 380 μatm to 1250 μatm. The effect of pCO2 on the physiological rates was enhanced at high temperature for ingestion, absorption, respiration and excretion. When the exposure period was extended to 31 days, the effect of pCO2 was significant on the ingestion rate only. All the physiological rates remained unchanged when temperature increased from 24 °C to 30 °C but the rates at 15 °C were significantly lower, irrespective of the duration of exposure. Our data suggested that a medium-term exposure to ocean acidification has no effect on the energetics of N. conoidalis. Nevertheless, the situation may be complicated by a longer term of exposure and/or a reduction in salinity in a warming world.
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Affiliation(s)
- Haoyu Zhang
- Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, China
| | - Paul K S Shin
- Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, China; State Key Laboratory in Marine Pollution, City University of Hong Kong, Hong Kong, China
| | - S G Cheung
- Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, China; State Key Laboratory in Marine Pollution, City University of Hong Kong, Hong Kong, China.
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20
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Aoki I, Mori I. Molecular biology of thermosensory transduction in C. elegans. Curr Opin Neurobiol 2015; 34:117-24. [PMID: 25840145 DOI: 10.1016/j.conb.2015.03.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/07/2015] [Accepted: 03/18/2015] [Indexed: 10/23/2022]
Abstract
As the environmental temperature prominently influences diverse biological aspects of the animals, thermosensation and the subsequent information processing in the nervous system has attracted much attention in biology. Thermotaxis in the nematode Caenorhabditis elegans is an ideal behavioral paradigm by which to address the molecular mechanism underlying thermosensory transduction. Molecular genetic analysis in combination with other physiological and behavioral studies revealed that sensation of ambient temperature is mediated mainly by cyclic guanosine monophosphate (cGMP) signaling in thermosensory neurons. The information of the previously perceived temperature is also stored within the thermosensory neurons, and the consequence of the comparison between the past and the present temperature is conveyed to the downstream interneurons to further regulate the motor-circuits that encode the locomotion.
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Affiliation(s)
- Ichiro Aoki
- Group of Molecular Neurobiology, Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Ikue Mori
- Group of Molecular Neurobiology, Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
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21
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Chao YC, Chen CC, Lin YC, Breer H, Fleischer J, Yang RB. Receptor guanylyl cyclase-G is a novel thermosensory protein activated by cool temperatures. EMBO J 2014; 34:294-306. [PMID: 25452496 DOI: 10.15252/embj.201489652] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Transmembrane guanylyl cyclases (GCs), with activity regulated by peptide ligands and/or calcium-binding proteins, are essential for various physiological and sensory processes. The mode of activation of the GC subtype GC-G, which is expressed in neurons of the Grueneberg ganglion that respond to cool temperatures, has been elusive. In searching for appropriate stimuli to activate GC-G, we found that its enzymatic activity is directly stimulated by cool temperatures. In this context, it was observed that dimerization/oligomerization of GC-G, a process generally considered as critical for enzymatic activity of GCs, is strongly enhanced by coolness. Moreover, heterologous expression of GC-G in cultured cells rendered these cells responsive to coolness; thus, the protein might be a sensor for cool temperatures. This concept is supported by the observation of substantially reduced coolness-induced response of Grueneberg ganglion neurons and coolness-evoked ultrasonic vocalization in GC-G-deficient mouse pups. GC-G may be a novel thermosensory protein with functional implications for the Grueneberg ganglion, a sensory organ responding to cool temperatures.
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Affiliation(s)
- Ying-Chi Chao
- Molecular Medicine Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chih-Cheng Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yuh-Charn Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Heinz Breer
- Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Joerg Fleischer
- Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Ruey-Bing Yang
- Molecular Medicine Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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22
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Pichlo M, Bungert-Plümke S, Weyand I, Seifert R, Bönigk W, Strünker T, Kashikar ND, Goodwin N, Müller A, Pelzer P, Van Q, Enderlein J, Klemm C, Krause E, Trötschel C, Poetsch A, Kremmer E, Kaupp UB, Körschen HG, Collienne U. High density and ligand affinity confer ultrasensitive signal detection by a guanylyl cyclase chemoreceptor. J Cell Biol 2014; 206:541-57. [PMID: 25135936 PMCID: PMC4137060 DOI: 10.1083/jcb.201402027] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 07/15/2014] [Indexed: 12/28/2022] Open
Abstract
Guanylyl cyclases (GCs), which synthesize the messenger cyclic guanosine 3',5'-monophosphate, control several sensory functions, such as phototransduction, chemosensation, and thermosensation, in many species from worms to mammals. The GC chemoreceptor in sea urchin sperm can decode chemoattractant concentrations with single-molecule sensitivity. The molecular and cellular underpinnings of such ultrasensitivity are not known for any eukaryotic chemoreceptor. In this paper, we show that an exquisitely high density of 3 × 10(5) GC chemoreceptors and subnanomolar ligand affinity provide a high ligand-capture efficacy and render sperm perfect absorbers. The GC activity is terminated within 150 ms by dephosphorylation steps of the receptor, which provides a means for precise control of the GC lifetime and which reduces "molecule noise." Compared with other ultrasensitive sensory systems, the 10-fold signal amplification by the GC receptor is surprisingly low. The hallmarks of this signaling mechanism provide a blueprint for chemical sensing in small compartments, such as olfactory cilia, insect antennae, or even synaptic boutons.
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Affiliation(s)
- Magdalena Pichlo
- Center of Advanced European Studies and Research, 53175 Bonn, Germany Marine Biological Laboratory, Woods Hole, MA 02543
| | - Stefanie Bungert-Plümke
- Marine Biological Laboratory, Woods Hole, MA 02543 Institute of Complex Systems (ICS-4), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Ingo Weyand
- Marine Biological Laboratory, Woods Hole, MA 02543 Institute of Complex Systems (ICS-4), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Reinhard Seifert
- Center of Advanced European Studies and Research, 53175 Bonn, Germany Marine Biological Laboratory, Woods Hole, MA 02543
| | - Wolfgang Bönigk
- Center of Advanced European Studies and Research, 53175 Bonn, Germany
| | - Timo Strünker
- Center of Advanced European Studies and Research, 53175 Bonn, Germany Marine Biological Laboratory, Woods Hole, MA 02543
| | - Nachiket Dilip Kashikar
- Center of Advanced European Studies and Research, 53175 Bonn, Germany Marine Biological Laboratory, Woods Hole, MA 02543 Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, England, UK
| | - Normann Goodwin
- Center of Advanced European Studies and Research, 53175 Bonn, Germany Marine Biological Laboratory, Woods Hole, MA 02543 Babraham Institute, Cambridge CB22 3AT, England, UK
| | - Astrid Müller
- Center of Advanced European Studies and Research, 53175 Bonn, Germany
| | - Patric Pelzer
- Marine Biological Laboratory, Woods Hole, MA 02543 Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Qui Van
- III. Physikalisches Institut, Universität Göttingen, 37077 Göttingen, Germany
| | - Jörg Enderlein
- III. Physikalisches Institut, Universität Göttingen, 37077 Göttingen, Germany
| | - Clementine Klemm
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Eberhard Krause
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | | | - Ansgar Poetsch
- Plant Biochemistry, Ruhr University Bochum. 44801 Bochum, Germany
| | - Elisabeth Kremmer
- Institut für Molekulare Immunologie, Helmholtz-Zentrum München, 81377 München, Germany
| | - U Benjamin Kaupp
- Center of Advanced European Studies and Research, 53175 Bonn, Germany Marine Biological Laboratory, Woods Hole, MA 02543
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23
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Hobert O. Development of left/right asymmetry in the Caenorhabditis elegans nervous system: From zygote to postmitotic neuron. Genesis 2014; 52:528-43. [DOI: 10.1002/dvg.22747] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/23/2014] [Accepted: 01/28/2014] [Indexed: 01/23/2023]
Affiliation(s)
- Oliver Hobert
- Department of Biochemistry and Molecular Biophysics; Howard Hughes Medical Institute, Columbia University Medical Center; New York New York
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24
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Sasakura H, Tsukada Y, Takagi S, Mori I. Japanese studies on neural circuits and behavior of Caenorhabditis elegans. Front Neural Circuits 2013; 7:187. [PMID: 24348340 PMCID: PMC3842693 DOI: 10.3389/fncir.2013.00187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 11/03/2013] [Indexed: 01/25/2023] Open
Abstract
The nematode Caenorhabditis elegans is an ideal organism for studying neural plasticity and animal behaviors. A total of 302 neurons of a C. elegans hermaphrodite have been classified into 118 neuronal groups. This simple neural circuit provides a solid basis for understanding the mechanisms of the brains of higher animals, including humans. Recent studies that employ modern imaging and manipulation techniques enable researchers to study the dynamic properties of nervous systems with great precision. Behavioral and molecular genetic analyses of this tiny animal have contributed greatly to the advancement of neural circuit research. Here, we will review the recent studies on the neural circuits of C. elegans that have been conducted in Japan. Several laboratories have established unique and clever methods to study the underlying neuronal substrates of behavioral regulation in C. elegans. The technological advances applied to studies of C. elegans have allowed new approaches for the studies of complex neural systems. Through reviewing the studies on the neuronal circuits of C. elegans in Japan, we will analyze and discuss the directions of neural circuit studies.
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Affiliation(s)
- Hiroyuki Sasakura
- Laboratory of Molecular Neurobiology, Division of Biological Science, Nagoya University Nagoya, Japan
| | - Yuki Tsukada
- Laboratory of Molecular Neurobiology, Division of Biological Science, Nagoya University Nagoya, Japan
| | - Shin Takagi
- Laboratory of Brain Function and Structure, Division of Biological Science, Nagoya University Nagoya, Japan
| | - Ikue Mori
- Laboratory of Molecular Neurobiology, Division of Biological Science, Nagoya University Nagoya, Japan
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25
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Murayama T, Maruyama IN. Decision making in C. elegans chemotaxis to alkaline pH: Competition between two sensory neurons, ASEL and ASH. Commun Integr Biol 2013; 6:e26633. [PMID: 24563708 PMCID: PMC3917959 DOI: 10.4161/cib.26633] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 09/25/2013] [Accepted: 09/26/2013] [Indexed: 11/19/2022] Open
Abstract
Monitoring of environmental and tissue pH is critical for animal survival. The nematode, Caenorhabditis elegans (C. elegans), is attracted to mildly alkaline pH, but avoids strongly alkaline pH. However, little is known about how the behavioral switching or decision making occurs. Genetic dissection and Ca2+ imaging have previously demonstrated that ASEL and ASH are the major sensory neurons responsible for attraction and repulsion, respectively. Here we report that unlike C. elegans wild type, mutants deficient in ASEL or ASH were repelled by mildly alkaline pH, or were attracted to strongly alkaline pH, respectively. These results suggest that signals through ASEL and ASH compete to determine the animal’s alkaline-pH chemotaxis. Furthermore, mutants with 2 ASEL neurons were more efficiently attracted to mildly alkaline pH than the wild type with a single ASEL neuron, indicating that higher activity of ASEL induces stronger attraction to mildly alkaline pH. This stronger attraction was overridden by normal activity of ASH, suggesting that ASH-mediated avoidance dominates ASEL-mediated attraction. Thus, C. elegans chemotactic behaviors to alkaline pH seems to be determined by signal strengths from the sensory neurons ASEL and ASH, and the behavior decision making seems to be the result of competition between the 2 sensory neurons.
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Affiliation(s)
- Takashi Murayama
- Okinawa Institute of Science and Technology Graduate University; Okinawa, Japan
| | - Ichi N Maruyama
- Okinawa Institute of Science and Technology Graduate University; Okinawa, Japan
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26
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Sassa T, Murayama T, Maruyama IN. Strongly alkaline pH avoidance mediated by ASH sensory neurons in C. elegans. Neurosci Lett 2013; 555:248-52. [PMID: 23769685 DOI: 10.1016/j.neulet.2013.06.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 05/31/2013] [Accepted: 06/04/2013] [Indexed: 11/28/2022]
Abstract
High pH is a noxious stimulus to animals, and their ability to avoid dangerously alkaline pH is critical for survival. However, the means by which they sense high pH has not been determined. The nematode Caenorhabditis elegans (C. elegans) avoids environmental pH above 10.5. In contrast, C. elegans mutants with structurally, developmentally, and/or functionally abnormal sensory cilia fail to avoid high pH, suggesting that sensory neurons in the cilia participate in sensing. Genetic rescue of the mutants indicates that ASH polymodal sensory neurons play a vital role in the process. Consistently, specific laser ablation of ASH neurons made animals insensitive to high pH. Furthermore, avoidance assays of other mutants also indicated that transient receptor potential vanilloid type (TRPV) ion channels encoded by osm-9 and ocr-2 are involved in sensing. Indeed, genetic rescue of osm-9 mutants by specifically expressing OSM-9 in ASH showed that TRPV channels play an essential role in sensing of high pH. Ca(2+) imaging in vivo also revealed that ASH neurons were activated by high pH stimulation, but ASH of osm-9 or ocr-2 mutants were not. These results demonstrate that in C. elegans, high pH is sensed by ASH nociceptors through opening of OSM-9/OCR-2 TRPV channels.
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Affiliation(s)
- Toshihiro Sassa
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-0495, Japan
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