1
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Zhang Y, Iino Y, Schafer WR. Behavioral plasticity. Genetics 2024; 228:iyae105. [PMID: 39158469 DOI: 10.1093/genetics/iyae105] [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: 02/01/2024] [Accepted: 06/10/2024] [Indexed: 08/20/2024] Open
Abstract
Behavioral plasticity allows animals to modulate their behavior based on experience and environmental conditions. Caenorhabditis elegans exhibits experience-dependent changes in its behavioral responses to various modalities of sensory cues, including odorants, salts, temperature, and mechanical stimulations. Most of these forms of behavioral plasticity, such as adaptation, habituation, associative learning, and imprinting, are shared with other animals. The C. elegans nervous system is considerably tractable for experimental studies-its function can be characterized and manipulated with molecular genetic methods, its activity can be visualized and analyzed with imaging approaches, and the connectivity of its relatively small number of neurons are well described. Therefore, C. elegans provides an opportunity to study molecular, neuronal, and circuit mechanisms underlying behavioral plasticity that are either conserved in other animals or unique to this species. These findings reveal insights into how the nervous system interacts with the environmental cues to generate behavioral changes with adaptive values.
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Affiliation(s)
- Yun Zhang
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Yuichi Iino
- Department of Biological Sciences, University of Tokyo, Tokyo 113-0032, Japan
| | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire CB2 0QH, UK
- Department of Biology, KU Leuven, 3000 Leuven, Belgium
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2
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Zhan C, Chen L, Guo D, Sun J, Duan Y, Zhang P, Li P, Ma L, Xu M, Wang Y, Bao H, Gao G, Liu L, Zhang K. An Intestinal Symbiotic Bacterial Strain of Oscheius chongmingensis Modulates Host Viability at Both Global and Post-Transcriptional Levels. Int J Mol Sci 2022; 23:ijms232314692. [PMID: 36499019 PMCID: PMC9739912 DOI: 10.3390/ijms232314692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/08/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
A rhabditid entomopathogenic nematode (EPN), Oscheius chongmingensis, has a stable symbiotic relationship with the bacterial strain Serratia nematodiphila S1 harbored in its intestines and drastically reduced viability when associated with a non-native strain (186) of the same bacterial species. This nematode is thus a good model for understanding the molecular mechanisms and interactions involved between a nematode host and a member of its intestinal microbiome. Transcriptome analysis and RNA-seq data indicated that expression levels of the majority (8797, 87.59%) of mRNAs in the non-native combination of O. chongmingensis and S. nematodiphila 186 were downregulated compared with the native combination, including strain S1. Accordingly, 88.84% of the total uniq-sRNAs mapped in the O. chongmingensis transcriptome were specific between the two combinations. Six DEGs, including two transcription factors (oc-daf-16 and oc-goa-1) and four kinases (oc-pdk-1, oc-akt-1, oc-rtk, and oc-fak), as well as an up-regulated micro-RNA, oc-miR-71, were found to demonstrate the regulatory mechanisms underlying diminished host viability induced by a non-native bacterial strain. Oc-rtk and oc-fak play key roles in the viability regulation of O. chongmingensis by positively mediating the expression of oc-daf-16 to indirectly impact its longevity and stress tolerances and by negatively regulating the expression of oc-goa-1 to affect the olfactory chemotaxis and fecundity. In response to the stress of invasion by the non-native strain, the expression of oc-miR-71 in the non-native combination was upregulated to downregulate the expression of its targeting oc-pdk-1, which might improve the localization and activation of the transcription factor DAF-16 in the nucleus to induce longevity extension and stress resistance enhancement to some extent. Our findings provide novel insight into comprehension of how nematodes deal with the stress of encountering novel potential bacterial symbionts at the physiological and molecular genetic levels and contribute to improved understanding of host-symbiont relationships generally.
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Affiliation(s)
- Chengxiu Zhan
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Long Chen
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Dandan Guo
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jing Sun
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yunbin Duan
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Panjie Zhang
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Pengpeng Li
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Lijun Ma
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Man Xu
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Ying Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Haoran Bao
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Guofu Gao
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Liwang Liu
- National Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crop (East China), Ministry of Agriculture and Rural Affairs, College of Horiticulture, Nanjing Agricultural University, Nanjing 210095, China
- Correspondence: (L.L.); (K.Z.)
| | - Keyun Zhang
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Correspondence: (L.L.); (K.Z.)
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Wang Y, Guo K, Wang Q, Zhong G, Zhang W, Jiang Y, Mao X, Li X, Huang Z. Caenorhabditis elegans as an emerging model in food and nutrition research: importance of standardizing base diet. Crit Rev Food Sci Nutr 2022; 64:3167-3185. [PMID: 36200941 DOI: 10.1080/10408398.2022.2130875] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
As a model organism that has helped revolutionize life sciences, Caenorhabditis elegans has been increasingly used in nutrition research. Here we explore the tradeoffs between pros and cons of its use as a dietary model based primarily on literature review from the past decade. We first provide an overview of its experimental strengths as an animal model, focusing on lifespan and healthspan, behavioral and physiological phenotypes, and conservation of key nutritional pathways. We then summarize recent advances of its use in nutritional studies, e.g. food preference and feeding behavior, sugar status and metabolic reprogramming, lifetime and transgenerational nutrition tracking, and diet-microbiota-host interactions, highlighting cutting-edge technologies originated from or developed in C. elegans. We further review current challenges of using C. elegans as a nutritional model, followed by in-depth discussions on potential solutions. In particular, growth scales and throughputs, food uptake mode, and axenic culture of C. elegans are appraised in the context of food research. We also provide perspectives for future development of chemically defined nematode food ("NemaFood") for C. elegans, which is now widely accepted as a versatile and affordable in vivo model and has begun to show transformative potential to pioneer nutrition science.
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Affiliation(s)
- Yuqing Wang
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
| | - Kaixin Guo
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Qiangqiang Wang
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
| | - Guohuan Zhong
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Center for Bioresources and Drug Discovery, School of Biosciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Wenjun Zhang
- Center for Bioresources and Drug Discovery, School of Biosciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yiyi Jiang
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Perfect Life & Health Institute, Zhongshan, Guangdong, China
| | - Xinliang Mao
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Perfect Life & Health Institute, Zhongshan, Guangdong, China
| | - Xiaomin Li
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Perfect Life & Health Institute, Zhongshan, Guangdong, China
| | - Zebo Huang
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Center for Bioresources and Drug Discovery, School of Biosciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
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4
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Asai A, Konno M, Ozaki M, Kawamoto K, Chijimatsu R, Kondo N, Hirotsu T, Ishii H. Scent test using Caenorhabditis elegans to screen for early-stage pancreatic cancer. Oncotarget 2021; 12:1687-1696. [PMID: 34434497 PMCID: PMC8378769 DOI: 10.18632/oncotarget.28035] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/13/2021] [Indexed: 12/12/2022] Open
Abstract
Although early detection and diagnosis are indispensable for improving the prognosis of patients with pancreatic cancer, both have yet to be achieved. Except for pancreatic cancer, other cancers have already been screened through scent tests using animals or microorganisms, including Caenorhabditis elegans. While such a method may greatly improve the prognosis of pancreatic cancer, no studies have investigated the same, mainly given the difficulty of collecting suitable samples from patients with early-stage pancreatic cancer. In this study, we organized a nationwide study group comprising high-volume centers throughout Japan to collect patients with very-early-stage pancreatic cancer (stage 0 or IA). We initially performed an open-label study involving 83 cases (stage 0–IV), with subsequent results showing significant differences after surgical removal in stage 0–IA (×10 dilution: p < 0.001; ×100 dilution: p < 0.001). Thereafter, a blinded study on 28 cases (11 patients with stage 0 or IA disease and 17 healthy volunteers) was conducted by comparing very-early-stage pancreatic cancer patients with healthy volunteers to determine whether C. elegans could detect the scent of cancer for the diagnosis of early-stage pancreatic cancer. Preoperative urine samples had a significantly higher chemotaxis index compared to postoperative samples in patients with pancreatic cancer [×10 dilution: p < 0.001, area under the receiver operating characteristic curve (AUC) = 0.845; ×100 dilution: p < 0.001, AUC = 0.820] and healthy volunteers (×10 dilution: p = 0.034; ×100 dilution: p = 0.088). Moreover, using the changes in preoperative and postoperative chemotaxis index, this method had a higher sensitivity for detecting early pancreatic cancer compared to existing diagnostic markers. The clinical application C. elegans for the early diagnosis of cancer can certainly be expected in the near future.
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Affiliation(s)
- Ayumu Asai
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Artificial Intelligence Research Center, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan
| | - Masamitsu Konno
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Present address: Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba, Japan
| | - Miyuki Ozaki
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Koichi Kawamoto
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Present address: Kinnki Regional Bureau of Health and Welfare, Osaka, Japan
| | - Ryota Chijimatsu
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Nobuaki Kondo
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Hirotsu Bio Science Inc., Chiyoda-Ku, Tokyo 102-0094, Japan
| | - Takaaki Hirotsu
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Hirotsu Bio Science Inc., Chiyoda-Ku, Tokyo 102-0094, Japan
| | - Hideshi Ishii
- Center of Medical Innovation and Translational Research (CoMIT), Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
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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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6
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Duan D, Zhang H, Yue X, Fan Y, Xue Y, Shao J, Ding G, Chen D, Li S, Cheng H, Zhang X, Zou W, Liu J, Zhao J, Wang L, Zhao B, Wang Z, Xu S, Wen Q, Liu J, Duan S, Kang L. Sensory Glia Detect Repulsive Odorants and Drive Olfactory Adaptation. Neuron 2020; 108:707-721.e8. [PMID: 32970991 DOI: 10.1016/j.neuron.2020.08.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 07/25/2020] [Accepted: 08/26/2020] [Indexed: 12/18/2022]
Abstract
Glia are typically considered as supporting cells for neural development and synaptic transmission. Here, we report an active role of a glia in olfactory transduction. As a polymodal sensory neuron in C. elegans, the ASH neuron is previously known to detect multiple aversive odorants. We reveal that the AMsh glia, a sheath for multiple sensory neurons including ASH, cell-autonomously respond to aversive odorants via G-protein-coupled receptors (GPCRs) distinct from those in ASH. Upon activation, the AMsh glia suppress aversive odorant-triggered avoidance and promote olfactory adaptation by inhibiting the ASH neuron via GABA signaling. Thus, we propose a novel two-receptor model where the glia and sensory neuron jointly mediate adaptive olfaction. Our study reveals a non-canonical function of glial cells in olfactory transduction, which may provide new insights into the glia-like supporting cells in mammalian sensory procession.
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Affiliation(s)
- Duo Duan
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310053, China; Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Hu Zhang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310053, China
| | - Xiaomin Yue
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310053, China
| | - Yuedan Fan
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310053, China
| | - Yadan Xue
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Jiajie Shao
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Gang Ding
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Du Chen
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Shitian Li
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Hankui Cheng
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Xiaoyan Zhang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Wenjuan Zou
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Jia Liu
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Jian Zhao
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Linmei Wang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Bingzhen Zhao
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhiping Wang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China
| | - Suhong Xu
- Center for Stem Cell and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Quan Wen
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jie Liu
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia
| | - Shumin Duan
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310053, China; Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China.
| | - Lijun Kang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang 310053, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310053, China.
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Kumar A, Baruah A, Tomioka M, Iino Y, Kalita MC, Khan M. Caenorhabditis elegans: a model to understand host-microbe interactions. Cell Mol Life Sci 2020; 77:1229-1249. [PMID: 31584128 PMCID: PMC11104810 DOI: 10.1007/s00018-019-03319-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/18/2019] [Accepted: 09/23/2019] [Indexed: 12/11/2022]
Abstract
Host-microbe interactions within the gut are fundamental to all higher organisms. Caenorhabditis elegans has been in use as a surrogate model to understand the conserved mechanisms in host-microbe interactions. Morphological and functional similarities of C. elegans gut with the human have allowed the mechanistic investigation of gut microbes and their effects on metabolism, development, reproduction, behavior, pathogenesis, immune responses and lifespan. Recent reports suggest their suitability for functional investigations of human gut bacteria, such as gut microbiota of healthy and diseased individuals. Our knowledge on the gut microbial diversity of C. elegans in their natural environment and the effect of host genetics on their core gut microbiota is important. Caenorhabditis elegans, as a model, is continuously bridging the gap in our understanding the role of genetics, environment, and dietary factors on physiology of the host.
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Affiliation(s)
- Arun Kumar
- Molecular Biology and Microbial Biotechnology Laboratory, Division of Life Sciences, Institute of Advanced Study in Science and Technology (IASST), Guwahati, Assam, 781035, India
| | - Aiswarya Baruah
- Department of Agricultural Biotechnology, Assam Agricultural University, Jorhat, Assam, 785013, India
| | - Masahiro Tomioka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Yuichi Iino
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan
- JST, CREST, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Mohan C Kalita
- Department of Biotechnology, Gauhati University, Guwahati, Assam, 781014, India
| | - Mojibur Khan
- Molecular Biology and Microbial Biotechnology Laboratory, Division of Life Sciences, Institute of Advanced Study in Science and Technology (IASST), Guwahati, Assam, 781035, India.
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8
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Ashida K, Shidara H, Hotta K, Oka K. Optical Dissection of Synaptic Plasticity for Early Adaptation in Caenorhabditis elegans. Neuroscience 2020; 428:112-121. [PMID: 31917348 DOI: 10.1016/j.neuroscience.2019.12.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 10/25/2022]
Abstract
To understand neuronal information processing, it is essential to investigate the input-output relationship and its modulation via detailed dissections of synaptic transmission between pre- and postsynaptic neurons. In Caenorhabditis elegans, pre-exposure to an odorant for five minutes reduces chemotaxis (early adaptation). AWC sensory neurons and AIY interneurons are crucial for this adaptation; AWC neurons sense volatile odors, and AIY interneurons receive glutamatergic inputs from AWC neurons. However, modulations via early adaptation of the input-output relationship between AWC and AIY are not well characterized. Here we use a variety of fluorescent imaging techniques to show that reduced synaptic-vesicle release without Ca2+ modulation in AWC neurons suppresses the Ca2+ response in AIY neurons via early adaptation. First, early adaptation modulates the Ca2+ response in AIY but not AWC neurons. Adaptation in the Ca2+ signal measured in AIY neurons is caused by adaptation in glutamate release from AWC neurons. Further, we found that a G protein γ-subunit, GPC-1, is related to modulation of glutamate input to AIY. Our results dissect the modulation of the pre- and postsynaptic relationship in vivo based on optical methods, and demonstrate the importance of neurotransmitter-release modulation in presynaptic neurons without Ca2+ modulation.
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Affiliation(s)
- Keita Ashida
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
| | - Hisashi Shidara
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
| | - Kohji Hotta
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
| | - Kotaro Oka
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan; Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City 80708, Taiwan; Waseda Research Institute for Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku, Tokyo 162-8480, Japan.
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9
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Coleman B, Topalidou I, Ailion M. Modulation of Gq-Rho Signaling by the ERK MAPK Pathway Controls Locomotion in Caenorhabditis elegans. Genetics 2018; 209:523-535. [PMID: 29615470 PMCID: PMC5972424 DOI: 10.1534/genetics.118.300977] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/29/2018] [Indexed: 12/17/2022] Open
Abstract
The heterotrimeric G protein Gq regulates neuronal activity through distinct downstream effector pathways. In addition to the canonical Gq effector phospholipase Cβ, the small GTPase Rho was recently identified as a conserved effector of Gq. To identify additional molecules important for Gq signaling in neurons, we performed a forward genetic screen in the nematode Caenorhabditis elegans for suppressors of the hyperactivity and exaggerated waveform of an activated Gq mutant. We isolated two mutations affecting the MAP kinase scaffold protein KSR-1 and found that KSR-1 modulates locomotion downstream of, or in parallel to, the Gq-Rho pathway. Through epistasis experiments, we found that the core ERK MAPK cascade is required for Gq-Rho regulation of locomotion, but that the canonical ERK activator LET-60/Ras may not be required. Through neuron-specific rescue experiments, we found that the ERK pathway functions in head acetylcholine neurons to control Gq-dependent locomotion. Additionally, expression of activated LIN-45/Raf in head acetylcholine neurons is sufficient to cause an exaggerated waveform phenotype and hypersensitivity to the acetylcholinesterase inhibitor aldicarb, similar to an activated Gq mutant. Taken together, our results suggest that the ERK MAPK pathway modulates the output of Gq-Rho signaling to control locomotion behavior in C. elegans.
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Affiliation(s)
- Brantley Coleman
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
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10
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de la Cova C, Townley R, Regot S, Greenwald I. A Real-Time Biosensor for ERK Activity Reveals Signaling Dynamics during C. elegans Cell Fate Specification. Dev Cell 2017; 42:542-553.e4. [PMID: 28826819 PMCID: PMC5595649 DOI: 10.1016/j.devcel.2017.07.014] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/19/2017] [Accepted: 07/20/2017] [Indexed: 01/06/2023]
Abstract
Kinase translocation reporters (KTRs) are genetically encoded fluorescent activity sensors that convert kinase activity into a nucleocytoplasmic shuttling equilibrium for visualizing single-cell signaling dynamics. Here, we adapt the first-generation KTR for extracellular signal-regulated kinase (ERK) to allow easy implementation in vivo. This sensor, "ERK-nKTR," allows quantitative and qualitative assessment of ERK activity by analysis of individual nuclei and faithfully reports ERK activity during development and neural function in diverse cell contexts in Caenorhabditis elegans. Analysis of ERK activity over time in the vulval precursor cells, a well-characterized paradigm of epidermal growth factor receptor (EGFR)-Ras-ERK signaling, has identified dynamic features not evident from analysis of developmental endpoints alone, including pulsatile frequency-modulated signaling associated with proximity to the EGF source. The toolkit described here will facilitate studies of ERK signaling in other C. elegans contexts, and the design features will enable implementation of this technology in other multicellular organisms.
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Affiliation(s)
- Claire de la Cova
- Department of Biological Sciences, Columbia University, New York, NY, USA; Department of Biochemistry & Molecular Biophysics, Columbia University Medical Center, New York, NY, USA
| | - Robert Townley
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Sergi Regot
- Department of Molecular Biology & Genetics, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Iva Greenwald
- Department of Biological Sciences, Columbia University, New York, NY, USA; Department of Biochemistry & Molecular Biophysics, Columbia University Medical Center, New York, NY, USA.
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11
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Uozumi T, Hamakawa M, Deno YK, Nakajo N, Hirotsu T. Voltage-dependent anion channel (VDAC-1) is required for olfactory sensing in Caenorhabditis elegans. Genes Cells 2015. [PMID: 26223767 DOI: 10.1111/gtc.12269] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Ras-MAP kinase signaling pathway plays important roles for the olfactory reception in olfactory neurons in Caenorhabditis elegans. However, given the absence of phosphorylation targets of MAPK in the olfactory neurons, the mechanism by which this pathway regulates olfactory function is unknown. Here, we used proteomic screening to identify the mitochondrial voltage-dependent anion channel VDAC-1 as a candidate target molecule of MAPK in the olfactory system of C. elegans. We found that Amphid Wing "C" (AWC) olfactory neuron-specific knockdown of vdac-1 caused severe defects in chemotaxis toward AWC-sensed odorants. We generated a new vdac-1 mutant using the CRISPR-Cas9 system, with this mutant also showing decreased chemotaxis toward odorants. This defect was rescued by AWC-specific expression of vdac-1, indicating that functions of VDAC-1 in AWC neurons are essential for normal olfactory reception in C. elegans. We observed that AWC-specific RNAi of vdac-1 reduced AWC calcium responses to odorant stimuli and caused a decrease in the quantity of mitochondria in the sensory cilia. Behavioral abnormalities in vdac-1 knockdown animals might therefore be due to reduction of AWC response, which might be caused by loss of mitochondria in the cilia. Here, we showed that the function of VDAC-1 is regulated by phosphorylation and identified Thr175 as the potential phosphorylation site of MAP kinase.
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Affiliation(s)
- Takayuki Uozumi
- Graduate School of Systems Life Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Masayuki Hamakawa
- Graduate School of Systems Life Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Yu-Ki Deno
- Graduate School of Systems Life Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Nobushige Nakajo
- Graduate School of Systems Life Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.,Department of Biology, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Takaaki Hirotsu
- Graduate School of Systems Life Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.,Department of Biology, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.,Division of Applied Medical Sensing, Research and Development Center for Taste and Odor Sensing, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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12
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Hirotsu T, Sonoda H, Uozumi T, Shinden Y, Mimori K, Maehara Y, Ueda N, Hamakawa M. A highly accurate inclusive cancer screening test using Caenorhabditis elegans scent detection. PLoS One 2015; 10:e0118699. [PMID: 25760772 PMCID: PMC4356513 DOI: 10.1371/journal.pone.0118699] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 01/22/2015] [Indexed: 01/12/2023] Open
Abstract
Early detection and treatment are of vital importance to the successful eradication of various cancers, and development of economical and non-invasive novel cancer screening systems is critical. Previous reports using canine scent detection demonstrated the existence of cancer-specific odours. However, it is difficult to introduce canine scent recognition into clinical practice because of the need to maintain accuracy. In this study, we developed a Nematode Scent Detection Test (NSDT) using Caenorhabditis elegans to provide a novel highly accurate cancer detection system that is economical, painless, rapid and convenient. We demonstrated wild-type C. elegans displayed attractive chemotaxis towards human cancer cell secretions, cancer tissues and urine from cancer patients but avoided control urine; in parallel, the response of the olfactory neurons of C. elegans to the urine from cancer patients was significantly stronger than to control urine. In contrast, G protein α mutants and olfactory neurons-ablated animals were not attracted to cancer patient urine, suggesting that C. elegans senses odours in urine. We tested 242 samples to measure the performance of the NSDT, and found the sensitivity was 95.8%; this is markedly higher than that of other existing tumour markers. Furthermore, the specificity was 95.0%. Importantly, this test was able to diagnose various cancer types tested at the early stage (stage 0 or 1). To conclude, C. elegans scent-based analyses might provide a new strategy to detect and study disease-associated scents.
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Affiliation(s)
- Takaaki Hirotsu
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan
- Department of Biology, Graduate School of Sciences, Kyushu University, Fukuoka, Japan
- Division of Applied Medical Sensing, Research and Development Center for Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
- * E-mail: (TH); (HS)
| | - Hideto Sonoda
- Division of Applied Medical Sensing, Research and Development Center for Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
- Department of General Surgery, Imari-Arita Kyoritsu Hospital, Saga, Japan
- Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
- * E-mail: (TH); (HS)
| | - Takayuki Uozumi
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan
| | - Yoshiaki Shinden
- Department of Surgery, Kyushu University Beppu Hospital, Oita, Japan
| | - Koshi Mimori
- Department of Surgery, Kyushu University Beppu Hospital, Oita, Japan
| | - Yoshihiko Maehara
- Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Naoko Ueda
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
| | - Masayuki Hamakawa
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan
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13
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Hamakawa M, Uozumi T, Ueda N, Iino Y, Hirotsu T. A role for Ras in inhibiting circular foraging behavior as revealed by a new method for time and cell-specific RNAi. BMC Biol 2015; 13:6. [PMID: 25603799 PMCID: PMC4321700 DOI: 10.1186/s12915-015-0114-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 01/09/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The nematode worm Caenorhabditis elegans, in which loss-of-function mutants and RNA interference (RNAi) models are available, is a model organism useful for analyzing effects of genes on various life phenomena, including behavior. In particular, RNAi is a powerful tool that enables time- or cell-specific knockdown via heat shock-inducible RNAi or cell-specific RNAi. However, conventional RNAi is insufficient for investigating pleiotropic genes with various sites of action and life stage-dependent functions. RESULTS Here, we investigated the Ras gene for its role in exploratory behavior in C. elegans. We found that, under poor environmental conditions, mutations in the Ras-MAPK signaling pathway lead to circular locomotion instead of normal exploratory foraging. Spontaneous foraging is regulated by a neural circuit composed of three classes of neurons: IL1, OLQ, and RMD, and we found that Ras functions in this neural circuit to modulate the direction of locomotion. We further observed that Ras plays an essential role in the regulation of GLR-1 glutamate receptor localization in RMD neurons. To investigate the temporal- and cell-specific profiles of the functions of Ras, we developed a new RNAi method that enables simultaneous time- and cell-specific knockdown. In this method, one RNA strand is expressed by a cell-specific promoter and the other by a heat shock promoter, resulting in only expression of double-stranded RNA in the target cell when heat shock is induced. This technique revealed that control of GLR-1 localization in RMD neurons requires Ras at the adult stage. Further, we demonstrated the application of this method to other genes. CONCLUSIONS We have established a new RNAi method that performs simultaneous time- and cell-specific knockdown and have applied this to reveal temporal profiles of the Ras-MAPK pathway in the control of exploratory behavior under poor environmental conditions.
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Affiliation(s)
- Masayuki Hamakawa
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, 812-8581, Japan.
| | - Takayuki Uozumi
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, 812-8581, Japan.
| | - Naoko Ueda
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, 812-8581, Japan.
| | - Yuichi Iino
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
| | - Takaaki Hirotsu
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, 812-8581, Japan. .,Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, 812-8581, Japan. .,Department of Biology, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan. .,Division of Applied Medical Sensing, Research and Development Center for Taste and Odor Sensing, Kyushu University, Fukuoka, 819-0395, Japan.
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14
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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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15
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Matsuura T, Izumi J, Hioki M, Nagaya H, Kobayashi Y. Sensory interaction between attractant diacetyl and repellent 2-nonanone in the nematode Caenorhabditis elegans. ACTA ACUST UNITED AC 2013; 319:285-95. [PMID: 23580469 DOI: 10.1002/jez.1795] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 11/12/2012] [Accepted: 03/01/2013] [Indexed: 11/08/2022]
Abstract
In the nematode Caenorhabditis elegans, the odorant diacetyl is sensed by AWA sensory neurons in the amphid sensory organ and elicits an attractive response, whereas 2-nonanone is sensed by AWB amphid sensory neurons and elicits an avoidance response. In the present study, we report that nematodes exhibit a sensory interaction between the attractant diacetyl and repellent 2-nonanone. In the presence of food, the chemotactic response to 0.01% diacetyl in nematodes preexposed to 0.1% diacetyl was greater than that in nonexposed naive nematodes (P < 0.05). The response to diacetyl was also greater in nematodes preexposed to 3% 2-nonanone in the presence of food than that in naive nematodes (P < 0.01). In the absence of food, the response to diacetyl in nematodes preexposed to diacetyl or 2-nonanone was significantly lower than that in nonexposed control nematodes (P < 0.01). The avoidance response to 10% 2-nonanone in nematodes preexposed to each odorant in the presence or absence of food was lower than that in nonexposed nematodes (P < 0.05). To confirm the validity of our results, the chemotactic responses to diacetyl and 2-nonanone were observed using che-3, odr-4, and odr-10 mutants, which exhibited defective sensitivity to diacetyl or 2-nonanone. From the results of our experiments, we conclude that nematodes exhibit a sensory interaction between diacetyl and 2-nonanone and speculate that this interaction is driven by higher-level neuronal circuits that underlie sensory integration.
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Affiliation(s)
- Tetsuya Matsuura
- Laboratory of Behavioral Physiology, Faculty of Engineering, Iwate University, Morioka, Japan. matsuura@iwate‐u.ac.jp
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16
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Temporally-regulated quick activation and inactivation of Ras is important for olfactory behaviour. Sci Rep 2012; 2:500. [PMID: 22787558 PMCID: PMC3391662 DOI: 10.1038/srep00500] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 06/22/2012] [Indexed: 12/30/2022] Open
Abstract
Responses to environmental stimuli are mediated by the activation and inactivation of various signalling proteins. However, the temporal dynamics of these events in living animals are not well understood. Here we show real-time imaging of the activity of the key regulator of the MAP kinase pathway, Ras, in living Caenorhabditis elegans and that Ras is transiently activated within a few seconds in olfactory neurons in response to increase in the concentration of odorants. This fast activation of Ras is dependent on the olfactory signalling pathway and Ras guanyl nucleotide-releasing protein (RasGRP). A negative feedback loop then quickly leads to Ras inactivation despite the continued presence of the odorant. Phenotypes of Ras mutants suggest this rapid activation and inactivation of Ras is important for regulation of interneuron activities and olfactory behaviours. Our results reveal novel kinetics and biological implication of transient activation of Ras in olfactory systems.
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17
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Yoshida K, Hirotsu T, Tagawa T, Oda S, Wakabayashi T, Iino Y, Ishihara T. Odour concentration-dependent olfactory preference change in C. elegans. Nat Commun 2012; 3:739. [PMID: 22415830 DOI: 10.1038/ncomms1750] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/14/2012] [Indexed: 01/28/2023] Open
Abstract
The same odorant can induce attractive or repulsive responses depending on its concentration in various animals including humans. However, little is understood about the neuronal basis of this behavioural phenomenon. Here we show that Caenorhabditis elegans avoids high concentrations of odorants that are attractive at low concentrations. Behavioural analyses and computer simulation reveal that the odour concentration-dependent behaviour is primarily generated by klinokinesis, a behavioural strategy in C. elegans. Genetic analyses and lesion experiments show that distinct combinations of sensory neurons function at different concentrations of the odorant; AWC and ASH sensory neurons have critical roles for attraction to or avoidance of the odorant, respectively. Moreover, we found that AWC neurons respond to only lower concentrations of the odorant, whereas ASH neurons respond to only higher concentrations of odorant. Hence, our study suggests that odour concentration coding in C. elegans mostly conforms to the labelled-line principle where distinct neurons respond to distinct stimuli.
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Affiliation(s)
- Kazushi Yoshida
- Department of Biophysics and Biochemistry, Graduate School of Sciences, The University of Tokyo, 113-0032, Japan
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18
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Hyde R, Corkins ME, Somers GA, Hart AC. PKC-1 acts with the ERK MAPK signaling pathway to regulate Caenorhabditis elegans mechanosensory response. GENES BRAIN AND BEHAVIOR 2011; 10:286-98. [PMID: 21143768 DOI: 10.1111/j.1601-183x.2010.00667.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In most animals, multiple genes encode protein kinase C (PKC) proteins. Pharmacological studies have revealed numerous roles for this protein family, yet the in vivo roles of specific PKC proteins and the functional targets of PKC activation are poorly understood. We find that in Caenorhabditis elegans, two PKC genes, pkc-1 and tpa-1, are required for mechanosensory response; the role of the nPKCε/η ortholog, pkc-1, was examined in detail. pkc-1 function is required for response to nose touch in adult C. elegans and pkc-1 likely acts in the interneurons that regulate locomotion which are direct synaptic targets of mechanosensory neurons. Previous studies have suggested numerous possible targets of pkc-1; our analysis indicates that pkc-1 may act via the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway. We find that ERK/MAPK pathway function is required for mechanosensory response in C. elegans and that at least one component of this pathway, lin-45 Raf, acts in interneurons of the mechanosensory circuit. Genetic analysis indicates that lin-45 and pkc-1 act together to regulate nose touch response. Thus, these results functionally link two conserved signaling pathways in adult C. elegans neurons and define distinct roles for PKC genes in vivo.
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Affiliation(s)
- R Hyde
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, MA, USA
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19
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Receptor-type guanylate cyclase is required for carbon dioxide sensation by Caenorhabditis elegans. Proc Natl Acad Sci U S A 2010; 108:254-9. [PMID: 21173231 DOI: 10.1073/pnas.1017354108] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
CO(2) is both a critical regulator of animal physiology and an important sensory cue for many animals for host detection, food location, and mate finding. The free-living soil nematode Caenorhabditis elegans shows CO(2) avoidance behavior, which requires a pair of ciliated sensory neurons, the BAG neurons. Using in vivo calcium imaging, we show that CO(2) specifically activates the BAG neurons and that the CO(2)-sensing function of BAG neurons requires TAX-2/TAX-4 cyclic nucleotide-gated ion channels and the receptor-type guanylate cyclase GCY-9. Our results delineate a molecular pathway for CO(2) sensing and suggest that activation of a receptor-type guanylate cyclase is an evolutionarily conserved mechanism by which animals detect environmental CO(2).
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20
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Yamada K, Hirotsu T, Matsuki M, Butcher RA, Tomioka M, Ishihara T, Clardy J, Kunitomo H, Iino Y. Olfactory plasticity is regulated by pheromonal signaling in Caenorhabditis elegans. Science 2010; 329:1647-50. [PMID: 20929849 PMCID: PMC3021133 DOI: 10.1126/science.1192020] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Population density-dependent dispersal is a well-characterized strategy of animal behavior in which dispersal rate increases when population density is higher. Caenorhabditis elegans shows positive chemotaxis to a set of odorants, but the chemotaxis switches from attraction to dispersal after prolonged exposure to the odorants. We show here that this plasticity of olfactory behavior is dependent on population density and that this regulation is mediated by pheromonal signaling. We show that a peptide, suppressor of NEP-2 (SNET-1), negatively regulates olfactory plasticity and that its expression is down-regulated by the pheromone. NEP-2, a homolog of the extracellular peptidase neprilysin, antagonizes SNET-1, and this function is essential for olfactory plasticity. These results suggest that population density information is transmitted through the external pheromone and endogenous peptide signaling to modulate chemotactic behavior.
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Affiliation(s)
- Koji Yamada
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Takaaki Hirotsu
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Department of Biology, Graduate School of Science, Kyushu University, Fukuoka, Japan
| | - Masahiro Matsuki
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Rebecca A Butcher
- Department of Biological Chemistry and Molecular Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Masahiro Tomioka
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Takeshi Ishihara
- Department of Biology, Graduate School of Science, Kyushu University, Fukuoka, Japan
| | - Jon Clardy
- Department of Biological Chemistry and Molecular Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Hirofumi Kunitomo
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Yuichi Iino
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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21
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Ardiel EL, Rankin CH. An elegant mind: Learning and memory in Caenorhabditis elegans. Learn Mem 2010; 17:191-201. [DOI: 10.1101/lm.960510] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Nuclear entry of a cGMP-dependent kinase converts transient into long-lasting olfactory adaptation. Proc Natl Acad Sci U S A 2010; 107:6016-21. [PMID: 20220099 DOI: 10.1073/pnas.1000866107] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To navigate a complex and changing environment, an animal's sensory neurons must continually adapt to persistent cues while remaining responsive to novel stimuli. Long-term exposure to an inherently attractive odor causes Caenorhabditis elegans to ignore that odor, a process termed odor adaptation. Odor adaptation is likely to begin within the sensory neuron, because it requires factors that act within these cells at the time of odor exposure. The process by which an olfactory sensory neuron makes a decisive shift over time from a receptive state to a lasting unresponsive one remains obscure. In C. elegans, adaptation to odors sensed by the AWC pair of olfactory neurons requires the cGMP-dependent protein kinase EGL-4. Using a fully functional, GFP-tagged EGL-4, we show here that prolonged odor exposure sends EGL-4 into the nucleus of the stimulated AWC neuron. This odor-induced nuclear translocation correlates temporally with the stable dampening of chemotaxis that is indicative of long-term adaptation. Long-term adaptation requires cGMP binding residues as well as an active EGL-4 kinase. We show here that EGL-4 nuclear accumulation is both necessary and sufficient to induce long-lasting odor adaptation. After it is in the AWC nucleus, EGL-4 decreases the animal's responsiveness to AWC-sensed odors by acting downstream of the primary sensory transduction. Thus, the EGL-4 protein kinase acts as a sensor that integrates odor signaling over time, and its nuclear translocation is an instructive switch that allows the animal to ignore persistent odors.
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O'Halloran DM, Altshuler-Keylin S, Lee JI, L'Etoile ND. Regulators of AWC-mediated olfactory plasticity in Caenorhabditis elegans. PLoS Genet 2009; 5:e1000761. [PMID: 20011101 PMCID: PMC2780698 DOI: 10.1371/journal.pgen.1000761] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 11/09/2009] [Indexed: 01/29/2023] Open
Abstract
While most sensory neurons will adapt to prolonged stimulation by down-regulating their responsiveness to the signal, it is not clear which events initiate long-lasting sensory adaptation. Likewise, we are just beginning to understand how the physiology of the adapted cell is altered. Caenorhabditis elegans is inherently attracted to specific odors that are sensed by the paired AWC olfactory sensory neurons. The attraction diminishes if the animal experiences these odors for a prolonged period of time in the absence of food. The AWC neuron responds acutely to odor-exposure by closing calcium channels. While odortaxis requires a Gα subunit protein, cGMP-gated channels, and guanylyl cyclases, adaptation to prolonged odor exposure requires nuclear entry of the cGMP-dependent protein kinase, EGL-4. We asked which candidate members of the olfactory signal transduction pathway promote nuclear entry of EGL-4 and which molecules might induce long-term adaptation downstream of EGL-4 nuclear entry. We found that initiation of long-term adaptation, as assessed by nuclear entry of EGL-4, is dependent on G-protein mediated signaling but is independent of fluxes in calcium levels. We show that long-term adaptation requires polyunsaturated fatty acids (PUFAs) that may act on the transient receptor potential (TRP) channel type V OSM-9 downstream of EGL-4 nuclear entry. We also present evidence that high diacylglycerol (DAG) levels block long-term adaptation without affecting EGL-4 nuclear entry. Our analysis provides a model for the process of long-term adaptation that occurs within the AWC neuron of C. elegans: G-protein signaling initiates long-lasting olfactory adaptation by promoting the nuclear entry of EGL-4, and once EGL-4 has entered the nucleus, processes such as PUFA activation of the TRP channel OSM-9 may dampen the output of the AWC neuron. Caenorhabditis elegans is capable of sensing a variety of attractive volatile compounds. These odors are the worm's “best guesses” as to how to track down food. Employing calculated approximations underlies a foraging strategy that is open to failure. When C. elegans track an odor which proves unrewarding, they must modify their behavior based on this experience. They also need to prevent over-stimulating their neurons. To accomplish this, C. elegans olfactory sensory neurons adapt to odors after a sustained exposure to odor in the absence of food. Within the pair of primary odor-sensory neurons, termed the AWCs, adaptation requires the cGMP-dependent protein kinase G (PKG), EGL-4. Exposing animals to AWC–sensed odors for approximately 60 minutes results in a long-lasting (∼3 hour) adaptation that requires the nuclear translocation of EGL-4. To understand how sensory transduction and desensitization machinery converge to achieve olfactory adaptation, we asked whether odor-induced EGL-4 nuclear accumulation was affected by gene mutations that abrogate either odor sensation of or adaptation to AWC–sensed odors. We find that G-protein signaling represents the integration point where primary odor sensation and odor adaptation pathways diverge. PUFA signaling, calcium, and decreased diacylglycerol all dampen the response of the AWC neuron to odor downstream of this divergence.
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Affiliation(s)
- Damien M. O'Halloran
- Center for Neuroscience, University of California Davis, Davis, California, United States of America
| | - Svetlana Altshuler-Keylin
- Center for Neuroscience, University of California Davis, Davis, California, United States of America
| | - Jin I. Lee
- Center for Neuroscience, University of California Davis, Davis, California, United States of America
| | - Noelle D. L'Etoile
- Center for Neuroscience, University of California Davis, Davis, California, United States of America
- Department of Psychiatry and Behavioral Sciences University of California Davis, Davis, California, United States of America
- * E-mail:
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24
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A trophic role for Wnt-Ror kinase signaling during developmental pruning in Caenorhabditis elegans. Nat Neurosci 2009; 12:981-7. [PMID: 19561603 DOI: 10.1038/nn.2347] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 05/05/2009] [Indexed: 11/09/2022]
Abstract
The molecular mechanism by which neurites are selected for elimination or incorporation into the mature circuit during developmental pruning remains unknown. The trophic theory postulates that local cues provided by target or surrounding cells act to inhibit neurite elimination. However, no widely conserved factor mediating this trophic function has been identified. We found that the developmental survival of specific neurites in Caenorhabditis elegans largely depends on detection of the morphogen Wnt by the Ror kinase CAM-1, which is a transmembrane tyrosine kinase with a Frizzled domain. Mutations in Wnt genes or in cam-1 enhanced neurite elimination, whereas overexpression of cam-1 inhibited neurite elimination in a Wnt-dependent manner. Moreover, mutations in these genes counteracted the effect of a mutation in mbr-1, which encodes a transcription factor that promotes neurite elimination. These results reveal the trophic role of an atypical Wnt pathway and reinforce the classical model of developmental pruning.
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25
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GPC-1, a G protein gamma-subunit, regulates olfactory adaptation in Caenorhabditis elegans. Genetics 2009; 181:1347-57. [PMID: 19189947 DOI: 10.1534/genetics.108.099002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Caenorhabditis elegans genome carries two Ggamma genes, gpc-1 and gpc-2, and two Gbeta genes, gpb-1 and gpb-2. Of these, gpc-2 and gpb-1 are expressed ubiquitously and are essential for viability. Through a genetic screen, we identified gpc-1 as essential for olfactory adaptation. While wild-type animals show decreased chemotaxis to the odorant benzaldehyde after a short preexposure to the odorant, gpc-1 mutants are still attracted to the odorant after the same preexposure. Cell-specific rescue experiments show that gpc-1 acts in the AWC olfactory neurons. Coexpression of GPC-1 and GPB-1, but not GPB-2, caused enhanced adaptation, indicating that GPC-1 may act with GPB-1. On the other hand, knock down of gpc-2 by cell-targeted RNAi caused reduced chemotaxis to the odorant in unadapted animals, indicating that GPC-2 mainly act for olfactory sensation and the two Ggamma's have differential functions. Nonetheless, overexpression of gpc-2 in AWC neurons rescued the adaptation defects of gpc-1 mutants, suggesting partially overlapping functions of the two Ggamma's. We further tested genetic interaction of gpc-1 with several other genes involved in olfactory adaptation. Our analyses place goa-1 Goalpha and let-60 Ras in parallel to gpc-1. In contrast, a gain-of-function mutation in egl-30 Gqalpha was epistatic to gpc-1, suggesting the possibility that gpc-1 Ggamma may act upstream of egl-30 Gqalpha.
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26
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Tsui D, van der Kooy D. Serotonin mediates a learned increase in attraction to high concentrations of benzaldehyde in aged C. elegans. Learn Mem 2008; 15:844-55. [PMID: 18984566 DOI: 10.1101/lm.1188208] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We utilized olfactory-mediated chemotaxis in Caenorhabditis elegans to examine the effect of aging on information processing and animal behavior. Wild-type (N2) young adults (day 4) initially approach and eventually avoid a point source of benzaldehyde. Aged adult animals (day 7) showed a stronger initial approach and a delayed avoidance to benzaldehyde compared with young adults. This delayed avoidance is due to an increased attraction rather than a decreased avoidance to benzaldehyde because (1) aged odr-3 mutants that are defective in odor attraction showed no delayed benzaldehyde avoidance, and (2) the delay in avoidance was also observed with another attractant diacetyl, but not the repellent octanol. Interestingly, the stronger expression of attractive behavior was only observed at benzaldehyde concentrations of 1% or higher. When worms were grown on nonbacterial growth media instead of Escherichia coli, thus removing the contingency between odors released from the food and the food itself, the increase in attraction to benzaldehyde disappeared. The increased attraction recovered after reinitiating the odor-food contingency by returning animals to E. coli food or supplementing axenic media with benzaldehyde. Moreover, serotonin-deficient mutants showed a deficit in the age-enhanced attraction. These results suggest that the increased attraction to benzaldehyde in aged worms is (1) serotonin mediated, (2) specific to high concentration of odorants, and (3) dependent on a learned association of odor metabolites with the presence of food. We propose that associative learning may selectively modify pathways at or downstream from a low-affinity olfactory receptor.
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Affiliation(s)
- David Tsui
- Department of Medical Genetics and Microbiology, University of Toronto, Toronto, Ontario, Canada.
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27
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Sengupta P. Generation and modulation of chemosensory behaviors in C. elegans. Pflugers Arch 2007; 454:721-34. [PMID: 17206445 DOI: 10.1007/s00424-006-0196-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 11/21/2006] [Accepted: 11/27/2006] [Indexed: 10/23/2022]
Abstract
C. elegans recognizes and discriminates among hundreds of chemical cues using a relatively compact chemosensory nervous system. Chemosensory behaviors are also modulated by prior experience and contextual cues. Because of the facile genetics and genomics possible in this organism, C. elegans provides an excellent system in which to explore the generation of chemosensory behaviors from the level of a single gene to the motor output. This review summarizes the current knowledge on the molecular and neuronal substrates of chemosensory behaviors and chemosensory behavioral plasticity in C. elegans.
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Affiliation(s)
- Piali Sengupta
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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28
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Kuhara A, Mori I. Molecular physiology of the neural circuit for calcineurin-dependent associative learning in Caenorhabditis elegans. J Neurosci 2006; 26:9355-64. [PMID: 16971519 PMCID: PMC6674598 DOI: 10.1523/jneurosci.0517-06.2006] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
How learning and memory is controlled at the neural circuit level is a fundamental question in neuroscience. However, molecular and cellular dissection of the neural circuits underlying learning and memory is extremely complicated in higher animals. Here, we report a simple neural circuit for learning behavior in Caenorhabditis elegans, where the calcium-activated phosphatase, calcineurin, acts as an essential modulator. The calcineurin mutant tax-6 showed defective feeding state-dependent learning behavior for temperature and salt. Surprisingly, defective associative learning between temperature and feeding state was caused by malfunctions of two pairs of directly connected interneurons, AIZ and RIA, in the mature nervous system. Monitoring temperature-evoked Ca2+ concentration changes in the AIZ-RIA neural pathway revealed that starvation, a conditioning factor, downregulated AIZ activity through calcineurin during associative learning between temperature and feeding state. Our results demonstrate the molecular and physiological mechanisms of a simple neural circuit for calcineurin-mediated associative learning behavior.
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Affiliation(s)
- Atsushi Kuhara
- Division of Biological Science, Graduate School of Science and Institute for Advanced Research, Nagoya University, Nagoya 464-8602, Japan
| | - Ikue Mori
- Division of Biological Science, Graduate School of Science and Institute for Advanced Research, Nagoya University, Nagoya 464-8602, Japan
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29
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Cortese MR, Di Vito M, De Giorgi C. The expression of the homologue of the Caenorhabditis elegans lin-45 raf is regulated in the motile stages of the plant parasitic nematode Meloidogyne artiellia. Mol Biochem Parasitol 2006; 149:38-47. [PMID: 16737746 DOI: 10.1016/j.molbiopara.2006.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 03/30/2006] [Accepted: 04/07/2006] [Indexed: 10/24/2022]
Abstract
The Ras-MAPK signal transduction pathway controls multiple developmental events and is involved in the processing of olfactory information in the free living nematode Caenorhabditis elegans. We have studied the Ras-MAPK pathway in the plant parasitic nematode Meloidogyne artiellia. The genes Mt-let-60, Mt-lin-45, Mt-mek-2 and Mt-mpk-1 have been isolated and sequenced. Each of them shows a high level of sequence similarity to its presumed ortholog in C. elegans and key functional domains are structurally conserved. Furthermore, we show that the M. artiellia recombinant MEK-2 protein can phosphorylate and activate the M. artiellia recombinant MPK-1 and the recombinant MEK-2 itself can be phosphorylated and activated by immunoprecipitated mammalian Raf. Surprisingly, the Mt-lin-45 message is not detectable in freshly emerged juveniles or in male specimens, suggesting that it may be quickly degraded in these life stages.
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30
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Faumont S, Boulin T, Hobert O, Lockery SR. Developmental regulation of whole cell capacitance and membrane current in identified interneurons in C. elegans. J Neurophysiol 2006; 95:3665-73. [PMID: 16554520 DOI: 10.1152/jn.00052.2006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Postembryonic developmental changes in electrophysiological properties of the AIY interneuron class were investigated using whole cell voltage clamp. AIY interneurons displayed an increase in cell capacitance during larval development, whereas steady-state current amplitude did not increase. The time course of the outward membrane current, carried at least in part by K+ ions, matured, from a slowly activating, sustained current to a rapidly activating, decaying current. We also investigated how the development of capacitance and outward current was altered by loss-of-function mutations in genes expressed in AIY. One such gene, the LIM homeobox gene ttx-3, is known to be involved in the specification of the AIY neuronal subtype. In ttx-3 mutants, capacitance and outward current matured precociously. In mutants of the gene wrk-1, an immunoglobulin superfamily (IgSF) member whose expression is regulated by ttx-3, capacitance matured normally, whereas outward current matured precociously. We conclude that AIY interneurons contain distinct pathways for regulating capacitance and membrane current.
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Affiliation(s)
- Serge Faumont
- Institute of Neuroscience, University of Oregon, Eugene, USA
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Matsuki M, Kunitomo H, Iino Y. Goalpha regulates olfactory adaptation by antagonizing Gqalpha-DAG signaling in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2006; 103:1112-7. [PMID: 16418272 PMCID: PMC1347976 DOI: 10.1073/pnas.0506954103] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The heterotrimeric G protein G(o) is abundantly expressed in the mammalian nervous system and modulates neural activities in response to various ligands. However, G(o)'s functions in living animals are less well understood. Here, we demonstrate that GOA-1 G(o)alpha has a fundamental role in olfactory adaptation in Caenorhabditis elegans. Impairment of GOA-1 G(o)alpha function and excessive activation of EGL-30 G(q)alpha cause a defect in adaptation to AWC-sensed odorants. These pathways antagonistically modulate olfactory adaptation in AWC chemosensory neurons. Wild-type animals treated with phorbol esters and double-mutant animals of diacylglycerol (DAG) kinases, dgk-3; dgk-1, also have a defect in adaptation, suggesting that elevated DAG signals disrupt normal adaptation. Constitutively active GOA-1 can suppress the adaptation defect of dgk-3; dgk-1 double mutants, whereas it fails to suppress the adaptation defect of animals with constitutively active EGL-30, implying that GOA-1 acts upstream of EGL-30 in olfactory adaptation. Our results suggest that down-regulation of EGL-30-DAG signaling by GOA-1 underlies olfactory adaptation and plasticity of chemotaxis.
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Affiliation(s)
- Masahiro Matsuki
- Molecular Genetics Research Laboratory and Graduate Program in Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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