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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Poole RJ, Flames N, Cochella L. Neurogenesis in Caenorhabditis elegans. Genetics 2024:iyae116. [PMID: 39167071 DOI: 10.1093/genetics/iyae116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Accepted: 06/24/2024] [Indexed: 08/23/2024] Open
Abstract
Animals rely on their nervous systems to process sensory inputs, integrate these with internal signals, and produce behavioral outputs. This is enabled by the highly specialized morphologies and functions of neurons. Neuronal cells share multiple structural and physiological features, but they also come in a large diversity of types or classes that give the nervous system its broad range of functions and plasticity. This diversity, first recognized over a century ago, spurred classification efforts based on morphology, function, and molecular criteria. Caenorhabditis elegans, with its precisely mapped nervous system at the anatomical level, an extensive molecular description of most of its neurons, and its genetic amenability, has been a prime model for understanding how neurons develop and diversify at a mechanistic level. Here, we review the gene regulatory mechanisms driving neurogenesis and the diversification of neuron classes and subclasses in C. elegans. We discuss our current understanding of the specification of neuronal progenitors and their differentiation in terms of the transcription factors involved and ensuing changes in gene expression and chromatin landscape. The central theme that has emerged is that the identity of a neuron is defined by modules of gene batteries that are under control of parallel yet interconnected regulatory mechanisms. We focus on how, to achieve these terminal identities, cells integrate information along their developmental lineages. Moreover, we discuss how neurons are diversified postembryonically in a time-, genetic sex-, and activity-dependent manner. Finally, we discuss how the understanding of neuronal development can provide insights into the evolution of neuronal diversity.
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Affiliation(s)
- Richard J Poole
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Nuria Flames
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia 46012, Spain
| | - Luisa Cochella
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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3
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Lee H, Boor SA, Hilbert ZA, Meisel JD, Park J, Wang Y, McKeown R, Fischer SEJ, Andersen EC, Kim DH. Genetic variants that modify neuroendocrine gene expression and foraging behavior of C. elegans. SCIENCE ADVANCES 2024; 10:eadk9481. [PMID: 38865452 PMCID: PMC11168454 DOI: 10.1126/sciadv.adk9481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 04/30/2024] [Indexed: 06/14/2024]
Abstract
The molecular mechanisms underlying diversity in animal behavior are not well understood. A major experimental challenge is determining the contribution of genetic variants that affect neuronal gene expression to differences in behavioral traits. In Caenorhabditis elegans, the neuroendocrine transforming growth factor-β ligand, DAF-7, regulates diverse behavioral responses to bacterial food and pathogens. The dynamic neuron-specific expression of daf-7 is modulated by environmental and endogenous bacteria-derived cues. Here, we investigated natural variation in the expression of daf-7 from the ASJ pair of chemosensory neurons. We identified common genetic variants in gap-2, encoding a Ras guanosine triphosphatase (GTPase)-activating protein homologous to mammalian synaptic Ras GTPase-activating protein, which modify daf-7 expression cell nonautonomously and promote exploratory foraging behavior in a partially DAF-7-dependent manner. Our data connect natural variation in neuron-specific gene expression to differences in behavior and suggest that genetic variation in neuroendocrine signaling pathways mediating host-microbe interactions may give rise to diversity in animal behavior.
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Affiliation(s)
- Harksun Lee
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Sonia A. Boor
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zoë A. Hilbert
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Joshua D. Meisel
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jaeseok Park
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Ye Wang
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Ryan McKeown
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Sylvia E. J. Fischer
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Harvard Medical School Initiative for RNA Medicine, Boston, MA 02115, USA
| | - Erik C. Andersen
- Department of Biology, Johns Hopkins University, Baltimore, MD 21212, USA
| | - Dennis H. Kim
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
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4
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Rodrigues DT, Padilha HA, Soares ATG, de Souza MEO, Guerra MT, Ávila DS. The Caenorhabditis elegans neuroendocrine system and their modulators: An overview. Mol Cell Endocrinol 2024; 586:112191. [PMID: 38382589 DOI: 10.1016/j.mce.2024.112191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 02/23/2024]
Abstract
In this review we seek to systematically bring what has been published in the literature about the nervous system, endocrine system, neuroendocrine relationships, neuroendocrine modulations and endocrine disruptors in the alternative model Caenorhabditis elegans. The serotonergic, dopaminergic, GABAergic and glutamatergic neurotransmitters are related to the modulation of the neuroendocrine axis, leading to the activation or inhibition of several processes that occur in the worm through distinct and interconnected pathways. Furthermore, this review addresses the gut-neuronal axis as it has been revealed in recent years that gut microbiota impacts on neuronal functions. This review also approaches xenobiotics that can positively or negatively impact the neuroendocrine system in C. elegans as in mammals, which allows the application of this nematode to screen new drugs and to identify toxicants that are endocrine disruptors.
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Affiliation(s)
- Daniela Teixeira Rodrigues
- Graduation Program in Biological Sciences- Toxicological Biochemistry, Federal University of Santa Maria, RS, Brazil
| | | | | | | | | | - Daiana Silva Ávila
- Graduation Program in Biological Sciences- Toxicological Biochemistry, Federal University of Santa Maria, RS, Brazil; Graduation Program in Biochemistry, Federal University of Pampa, Uruguaiana, RS, Brazil.
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5
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Luo J, Bainbridge C, Miller RM, Barrios A, Portman DS. C. elegans males optimize mate-preference decisions via sex-specific responses to multimodal sensory cues. Curr Biol 2024; 34:1309-1323.e4. [PMID: 38471505 PMCID: PMC10965367 DOI: 10.1016/j.cub.2024.02.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 12/07/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024]
Abstract
For sexually reproducing animals, selecting optimal mates is important for maximizing reproductive fitness. In the nematode C. elegans, populations reproduce largely by hermaphrodite self-fertilization, but the cross-fertilization of hermaphrodites by males also occurs. Males' ability to recognize hermaphrodites involves several sensory cues, but an integrated view of the ways males use these cues in their native context to assess characteristics of potential mates has been elusive. Here, we examine the mate-preference behavior of C. elegans males evoked by natively produced cues. We find that males use a combination of volatile sex pheromones (VSPs), ascaroside sex pheromones, surface-associated cues, and other signals to assess multiple features of potential mates. Specific aspects of mate preference are communicated by distinct signals: developmental stage and sex are signaled by ascaroside pheromones and surface cues, whereas the presence of a self-sperm-depleted hermaphrodite is likely signaled by VSPs. Furthermore, males prefer to interact with virgin over mated, and well-fed over food-deprived, hermaphrodites; these preferences are likely adaptive and are also mediated by ascarosides and other cues. Sex-typical mate-preference behavior depends on the sexual state of the nervous system, such that pan-neuronal genetic masculinization in hermaphrodites generates male-typical social behavior. We also identify an unexpected role for the sex-shared ASH sensory neurons in male attraction to ascaroside sex pheromones. Our findings lead to an integrated view in which the distinct physical properties of various mate-preference cues guide a flexible, stepwise behavioral program by which males assess multiple features of potential mates to optimize mate preference.
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Affiliation(s)
- Jintao Luo
- School of Life Sciences, Xiamen University, Xiamen 361102, Fujian, China; Department of Biomedical Genetics and Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY 14642, USA
| | - Chance Bainbridge
- Department of Biomedical Genetics and Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY 14642, USA
| | - Renee M Miller
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY 14620, USA
| | - Arantza Barrios
- Department of Cell and Developmental Biology, University College London, London WC1E 6DE, UK
| | - Douglas S Portman
- Department of Biomedical Genetics and Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY 14642, USA.
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6
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Boor SA, Meisel JD, Kim DH. Neuroendocrine gene expression coupling of interoceptive bacterial food cues to foraging behavior of C. elegans. eLife 2024; 12:RP91120. [PMID: 38231572 PMCID: PMC10945577 DOI: 10.7554/elife.91120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024] Open
Abstract
Animal internal state is modulated by nutrient intake, resulting in behavioral responses to changing food conditions. The neural mechanisms by which internal states are generated and maintained are not well understood. Here, we show that in the nematode Caenorhabditis elegans, distinct cues from bacterial food - interoceptive signals from the ingestion of bacteria and gustatory molecules sensed from nearby bacteria - act antagonistically on the expression of the neuroendocrine TGF-beta ligand DAF-7 from the ASJ pair of sensory neurons to modulate foraging behavior. A positive-feedback loop dependent on the expression of daf-7 from the ASJ neurons acts to promote transitions between roaming and dwelling foraging states and influence the persistence of roaming states. SCD-2, the C. elegans ortholog of mammalian anaplastic lymphoma kinase (ALK), which has been implicated in the central control of metabolism of mammals, functions in the AIA interneurons to regulate foraging behavior and cell-non-autonomously control the expression of DAF-7 from the ASJ neurons. Our data establish how a dynamic neuroendocrine daf-7 expression feedback loop regulated by SCD-2 functions to couple sensing and ingestion of bacterial food to foraging behavior. We further suggest that this neuroendocrine feedback loop underlies previously characterized exploratory behaviors in C. elegans. Our data suggest that the expression of daf-7 from the ASJ neurons contributes to and is correlated with an internal state of 'unmet need' that regulates exploratory foraging behavior in response to bacterial cues in diverse physiological contexts.
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Affiliation(s)
- Sonia A Boor
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Joshua D Meisel
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
| | - Dennis H Kim
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
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7
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Hulsey-Vincent H, Athanasopoulos A, McGehee A, Kowalski JR, Dahlberg C. A Fiji protocol for analyzing puncta is a robust tool for measuring GLR-1::GFP accumulation in the ventral nerve cord of C. elegans. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.001004. [PMID: 38170032 PMCID: PMC10760542 DOI: 10.17912/micropub.biology.001004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 12/03/2023] [Accepted: 12/12/2023] [Indexed: 01/05/2024]
Abstract
In C. elegans, DAF-7/TGF-beta signaling regulates development, metabolism, and behavior. In addition loss of daf-7 leads to an increase of the glutamate receptor GLR-1. In daf-7(e1372) mutants, GLR-1 tagged with GFP (GLR-1::GFP) accumulates in wide puncta along the ventral nerve cord of the animal. Previous automated analyses of GLR-1::GFP accumulation relied on the proprietary software, IgorPro, for measurement of GLR-1::GFP puncta size, intensity, and density. We did a side-by-side comparison of analyses by IgorPro and an open source macro written for Fiji to analyze images from animals expressing GLR-1::GFP in wild type and daf-7(e1372) backgrounds. Analyses by the two programs were in strong agreement and are in accordance with previously published data on the effects of daf-7(e1372) on GLR-1::GFP accumulation. Based on these data, we conclude that the Fiji platform is a robust method for analyzing the accumulation of a fluorescently-tagged neurotransmitter receptor and that the Fiji puncta plugin will be applicable for image analysis for other neural markers.
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Affiliation(s)
| | | | - Annette McGehee
- Biology, Suffolk University, Boston, Massachusetts, United States
| | | | - Caroline Dahlberg
- Biology, Western Washington University, Bellingham, Washington, United States
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8
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Boor SA, Meisel JD, Kim DH. Neuroendocrine Gene Expression Coupling of Interoceptive Bacterial Food Cues to Foraging Behavior of C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.15.549072. [PMID: 37503081 PMCID: PMC10369937 DOI: 10.1101/2023.07.15.549072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Animal internal state is modulated by nutrient intake, resulting in behavioral responses to changing food conditions. The neural mechanisms by which internal states are generated and maintained are not well understood. Here, we show that in the nematode Caenorhabditis elegans, distinct cues from bacterial food - interoceptive signals from the ingestion of bacteria and gustatory molecules sensed from nearby bacteria - act antagonistically on the expression of the neuroendocrine TGF-beta ligand DAF-7 from the ASJ pair of sensory neurons to modulate foraging behavior. A positive-feedback loop dependent on the expression of daf-7 from the ASJ neurons acts to promote transitions between roaming and dwelling foraging states and influence the persistence of roaming states. SCD-2, the C. elegans ortholog of mammalian Anaplastic Lymphoma Kinase (ALK), which has been implicated in the central control of metabolism of mammals, functions in the AIA interneurons to regulate foraging behavior and cell-non-autonomously control the expression of DAF-7 from the ASJ neurons. Our data establish how a dynamic neuroendocrine daf-7 expression feedback loop regulated by SCD-2 functions to couple sensing and ingestion of bacterial food to foraging behavior. We further suggest that this neuroendocrine feedback loop underlies previously characterized exploratory behaviors in C. elegans. Our data suggest that the expression of daf-7 from the ASJ neurons contributes to and is correlated with an internal state of "unmet need" that regulates exploratory foraging behavior in response to bacterial cues in diverse physiological contexts.
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Affiliation(s)
- Sonia A. Boor
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Joshua D. Meisel
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114
| | - Dennis H. Kim
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115
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9
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Sepulveda NB, Chen D, Petrella LN. Moderate heat stress-induced sterility is due to motility defects and reduced mating drive in Caenorhabditis elegans males. J Exp Biol 2023; 226:jeb245546. [PMID: 37724024 DOI: 10.1242/jeb.245546] [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: 01/19/2023] [Accepted: 09/11/2023] [Indexed: 09/20/2023]
Abstract
Moderate heat stress negatively impacts fertility in sexually reproducing organisms at sublethal temperatures. These moderate heat stress effects are typically more pronounced in males. In some species, sperm production, quality and motility are the primary cause of male infertility during moderate heat stress. However, this is not the case in the model nematode Caenorhabditis elegans, where changes in mating behavior are the primary cause of fertility loss. We report that heat-stressed C. elegans males are more motivated to locate and remain on food and less motivated to leave food to find and mate with hermaphrodites than their unstressed counterparts. Heat-stressed males also demonstrate a reduction in motility that likely limits their ability to mate. Collectively these changes result in a dramatic reduction in reproductive success. The reduction in mate-searching behavior may be partially due to increased expression of the chemoreceptor odr-10 in the AWA sensory neurons, which is a marker for starvation in males. These results demonstrate that moderate heat stress may have profound and previously underappreciated effects on reproductive behaviors. As climate change continues to raise global temperatures, it will be imperative to understand how moderate heat stress affects behavioral and motility elements critical to reproduction.
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Affiliation(s)
- Nicholas B Sepulveda
- Department of Biological Sciences, Marquette University, 1428 W Clybourn St., Milwaukee, WI 53217, USA
| | - Donald Chen
- Department of Biological Sciences, Marquette University, 1428 W Clybourn St., Milwaukee, WI 53217, USA
| | - Lisa N Petrella
- Department of Biological Sciences, Marquette University, 1428 W Clybourn St., Milwaukee, WI 53217, USA
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10
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Portman DS, Díaz-Balzac CA. Developmental biology: A hole in the matrix. Curr Biol 2023; 33:R1016-R1018. [PMID: 37816322 DOI: 10.1016/j.cub.2023.08.082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Neurons must access the environment to gather information, but this exposure must be carefully managed. New work finds that glial cells, the non-neuronal component of the nervous system, control environmental access by stage- and sex-specific patterning of the extracellular matrix.
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Affiliation(s)
- Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA; Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA; Department of Biology, University of Rochester, 402 Hutchison Hall, Rochester, NY 14627, USA.
| | - Carlos A Díaz-Balzac
- Department of Biomedical Genetics, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA; Department of Medicine, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
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11
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Lee H, Boor SA, Hilbert ZA, Meisel JD, Park J, Wang Y, McKeown R, Fischer SEJ, Andersen EC, Kim DH. Genetic Variants That Modify the Neuroendocrine Regulation of Foraging Behavior in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.09.556976. [PMID: 37745484 PMCID: PMC10515746 DOI: 10.1101/2023.09.09.556976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The molecular mechanisms underlying diversity in animal behavior are not well understood. A major experimental challenge is determining the contribution of genetic variants that affect neuronal gene expression to differences in behavioral traits. The neuroendocrine TGF-beta ligand, DAF-7, regulates diverse behavioral responses of Caenorhabditis elegans to bacterial food and pathogens. The dynamic neuron-specific expression of daf-7 is modulated by environmental and endogenous bacteria-derived cues. Here, we investigated natural variation in the expression of daf-7 from the ASJ pair of chemosensory neurons and identified common variants in gap-2, encoding a GTPase-Activating Protein homologous to mammalian SynGAP proteins, which modify daf-7 expression cell-non-autonomously and promote exploratory foraging behavior in a DAF-7-dependent manner. Our data connect natural variation in neuron-specific gene expression to differences in behavior and suggest that genetic variation in neuroendocrine signaling pathways mediating host-microbe interactions may give rise to diversity in animal behavior.
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Affiliation(s)
- Harksun Lee
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School; Boston, 02115, USA
| | - Sonia A. Boor
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School; Boston, 02115, USA
- Department of Biology, Massachusetts Institute of Technology; Cambridge, 02139, USA
| | - Zoë A. Hilbert
- Department of Biology, Massachusetts Institute of Technology; Cambridge, 02139, USA
| | - Joshua D. Meisel
- Department of Biology, Massachusetts Institute of Technology; Cambridge, 02139, USA
| | - Jaeseok Park
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School; Boston, 02115, USA
| | - Ye Wang
- Department of Molecular Biosciences, Northwestern University; Evanston, 60208, USA
| | - Ryan McKeown
- Department of Molecular Biosciences, Northwestern University; Evanston, 60208, USA
| | - Sylvia E. J. Fischer
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School; Boston, 02115, USA
| | - Erik C. Andersen
- Department of Molecular Biosciences, Northwestern University; Evanston, 60208, USA
| | - Dennis H. Kim
- Division of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School; Boston, 02115, USA
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12
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Luo J, Barrios A, Portman DS. C. elegans males optimize mate-choice decisions via sex-specific responses to multimodal sensory cues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.08.536021. [PMID: 37066192 PMCID: PMC10104232 DOI: 10.1101/2023.04.08.536021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
For sexually reproducing animals, selecting optimal mates is essential for maximizing reproductive fitness. Because the nematode C. elegans reproduces mostly by self-fertilization, little is known about its mate-choice behaviors. While several sensory cues have been implicated in males' ability to recognize hermaphrodites, achieving an integrated understanding of the ways males use these cues to assess relevant characteristics of potential mates has proven challenging. Here, we use a choice-based social-interaction assay to explore the ability of C. elegans males to make and optimize mate choices. We find that males use a combination of volatile sex pheromones (VSPs), ascaroside pheromones, surface-bound chemical cues, and other signals to robustly assess a variety of features of potential mates. Specific aspects of mate choice are communicated by distinct signals: the presence of a sperm-depleted, receptive hermaphrodite is likely signaled by VSPs, while developmental stage and sex are redundantly specified by ascaroside pheromones and surface-associated cues. Ascarosides also signal nutritional information, allowing males to choose well-fed over starved mates, while both ascarosides and surface-associated cues cause males to prefer virgin over previously mated hermaphrodites. The male-specificity of these behavioral responses is determined by both male-specific neurons and the male state of sex-shared circuits, and we reveal an unexpected role for the sex-shared ASH sensory neurons in male attraction to endogenously produced hermaphrodite ascarosides. Together, our findings lead to an integrated view of the signaling and behavioral mechanisms by which males use diverse sensory cues to assess multiple features of potential mates and optimize mate choice.
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Affiliation(s)
- Jintao Luo
- School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
- Department of Biomedical Genetics and Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY 14642
| | - Arantza Barrios
- Department of Cell and Developmental Biology, University College London, London WC1E 6DE, UK
| | - Douglas S. Portman
- Department of Biomedical Genetics and Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY 14642
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13
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Yu Y, Chen J, An L, Huang T, Wang W, Cheng Z, Wang L, Xu X, Zhao Z, Fu X, Ma J. Knockdown of phosphatases of regenerating liver-1 prolongs the lifespan of Caenorhabditis elegans via activating DAF-16/FOXO. FASEB J 2023; 37:e22844. [PMID: 36906287 DOI: 10.1096/fj.202202003r] [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: 11/29/2022] [Revised: 01/20/2023] [Accepted: 02/15/2023] [Indexed: 03/13/2023]
Abstract
Phosphatases of regenerating liver (PRLs) are dual-specificity protein phosphatases. The aberrant expression of PRLs threatens human health, but their biological functions and pathogenic mechanisms are unclear yet. Herein, the structure and biological functions of PRLs were investigated using the Caenorhabditis elegans (C. elegans). Structurally, this phosphatase in C. elegans, named PRL-1, consisted of a conserved signature sequence WPD loop and a single C(X)5 R domain. Besides, by Western blot, immunohistochemistry and immunofluorescence staining, PRL-1 was proved to mainly express in larval stages and express in intestinal tissues. Afterward, by feeding-based RNA-interference method, knockdown of prl-1 prolonged the lifespan of C. elegans but also improved their healthspan, such as locomotion, pharyngeal pumping frequency, and defecation interval time. Furthermore, the above effects of prl-1 appeared to be taken without acting on germline signaling, diet restriction pathway, insulin/insulin-like growth factor 1 signaling pathway, and SIR-2.1 but through a DAF-16-dependent pathway. Moreover, knockdown of prl-1 induced the nuclear translocation of DAF-16, and upregulated the expression of daf-16, sod-3, mtl-1, and ctl-2. Finally, suppression of prl-1 also reduced the ROS. In conclusion, suppression of prl-1 enhanced the lifespan and survival quality of C. elegans, which provides a theoretical basis for the pathogenesis of PRLs in related human diseases.
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Affiliation(s)
- Yaoru Yu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Jing Chen
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Lu An
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Tianci Huang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Wenbo Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Ziqi Cheng
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Lu Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Xuesong Xu
- Clinical Laboratory of China-Japan Union Hospital, Jilin University, Changchun, China
| | - Zhizhuang Zhao
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Xueqi Fu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Junfeng Ma
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
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14
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Lo WS, Roca M, Dardiry M, Mackie M, Eberhardt G, Witte H, Hong R, Sommer RJ, Lightfoot JW. Evolution and Diversity of TGF-β Pathways are Linked with Novel Developmental and Behavioral Traits. Mol Biol Evol 2022; 39:msac252. [PMID: 36469861 PMCID: PMC9733428 DOI: 10.1093/molbev/msac252] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 10/19/2022] [Accepted: 11/07/2022] [Indexed: 12/12/2022] Open
Abstract
Transforming growth factor-β (TGF-β) signaling is essential for numerous biologic functions. It is a highly conserved pathway found in all metazoans including the nematode Caenorhabditis elegans, which has also been pivotal in identifying many components. Utilizing a comparative evolutionary approach, we explored TGF-β signaling in nine nematode species and revealed striking variability in TGF-β gene frequency across the lineage. Of the species analyzed, gene duplications in the DAF-7 pathway appear common with the greatest disparity observed in Pristionchus pacificus. Specifically, multiple paralogues of daf-3, daf-4 and daf-7 were detected. To investigate this additional diversity, we induced mutations in 22 TGF-β components and generated corresponding double, triple, and quadruple mutants revealing both conservation and diversification in function. Although the DBL-1 pathway regulating body morphology appears highly conserved, the DAF-7 pathway exhibits functional divergence, notably in some aspects of dauer formation. Furthermore, the formation of the phenotypically plastic mouth in P. pacificus is partially influenced through TGF-β with the strongest effect in Ppa-tag-68. This appears important for numerous processes in P. pacificus but has no known function in C. elegans. Finally, we observe behavioral differences in TGF-β mutants including in chemosensation and the establishment of the P. pacificus kin-recognition signal. Thus, TGF-β signaling in nematodes represents a stochastic genetic network capable of generating novel functions through the duplication and deletion of associated genes.
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Affiliation(s)
- Wen-Sui Lo
- Department for Integrative Evolutionary Biology, Max-Planck Institute for Biology Tübingen, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Marianne Roca
- Max Planck Research Group Genetics of Behavior, Max Planck Institute for Neurobiology of Behavior—Caesar, Ludwig-Erhard-Allee 2, 53175, Bonn, Germany
| | - Mohannad Dardiry
- Department for Integrative Evolutionary Biology, Max-Planck Institute for Biology Tübingen, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Marisa Mackie
- Department of Biology, California State University, Northridge, CA
| | - Gabi Eberhardt
- Department for Integrative Evolutionary Biology, Max-Planck Institute for Biology Tübingen, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Hanh Witte
- Department for Integrative Evolutionary Biology, Max-Planck Institute for Biology Tübingen, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Ray Hong
- Department of Biology, California State University, Northridge, CA
| | - Ralf J Sommer
- Department for Integrative Evolutionary Biology, Max-Planck Institute for Biology Tübingen, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - James W Lightfoot
- Max Planck Research Group Genetics of Behavior, Max Planck Institute for Neurobiology of Behavior—Caesar, Ludwig-Erhard-Allee 2, 53175, Bonn, Germany
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15
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Cheng X, Yan Z, Su Z, Liu J. The transforming growth factor beta ligand TIG-2 modulates the function of neuromuscular junction and muscle energy metabolism in Caenorhabditis elegans. Front Mol Neurosci 2022; 15:962974. [PMID: 36385772 PMCID: PMC9650414 DOI: 10.3389/fnmol.2022.962974] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/03/2022] [Indexed: 07/22/2023] Open
Abstract
Deciphering the physiological function of TGF-β (the transforming growth factor beta) family ligands is import for understanding the role of TGF-β in animals' development and aging. Here, we investigate the function of TIG-2, one of the ligands in Caenorhabditis elegans TGF-β family, in animals' behavioral modulation. Our results show that a loss-of-function mutation in tig-2 gene result in slower locomotion speed in the early adulthood and an increased density of cholinergic synapses, but a decreased neurotransmitter release at neuromuscular junctions (NMJs). Further tissue-specific rescue results reveal that neuronal and intestinal TIG-2 are essential for the formation of cholinergic synapses at NMJs. Interestingly, tig-2(ok3416) mutant is characterized with reduced muscle mitochondria content and adenosine triphosphate (ATP) production, although the function of muscle acetylcholine receptors and the morphology muscle fibers in the mutant are comparable to that in wild-type animals. Our result suggests that TIG-2 from different neuron and intestine regulates worm locomotion by modulating synaptogenesis and neurotransmission at NMJs, as well as energy metabolism in postsynaptic muscle cells.
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Affiliation(s)
- Xinran Cheng
- Neuroscience Program, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Zhenzhen Yan
- Neuroscience Program, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Dr. Neher’s Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macao, Macao SAR, China
| | - Zexiong Su
- Neuroscience Program, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Jie Liu
- Neuroscience Program, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
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16
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McLachlan IG, Kramer TS, Dua M, DiLoreto EM, Gomes MA, Dag U, Srinivasan J, Flavell SW. Diverse states and stimuli tune olfactory receptor expression levels to modulate food-seeking behavior. eLife 2022; 11:e79557. [PMID: 36044259 PMCID: PMC9433090 DOI: 10.7554/elife.79557] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 08/19/2022] [Indexed: 12/24/2022] Open
Abstract
Animals must weigh competing needs and states to generate adaptive behavioral responses to the environment. Sensorimotor circuits are thus tasked with integrating diverse external and internal cues relevant to these needs to generate context-appropriate behaviors. However, the mechanisms that underlie this integration are largely unknown. Here, we show that a wide range of states and stimuli converge upon a single Caenorhabditis elegans olfactory neuron to modulate food-seeking behavior. Using an unbiased ribotagging approach, we find that the expression of olfactory receptor genes in the AWA olfactory neuron is influenced by a wide array of states and stimuli, including feeding state, physiological stress, and recent sensory cues. We identify odorants that activate these state-dependent olfactory receptors and show that altered expression of these receptors influences food-seeking and foraging. Further, we dissect the molecular and neural circuit pathways through which external sensory information and internal nutritional state are integrated by AWA. This reveals a modular organization in which sensory and state-related signals arising from different cell types in the body converge on AWA and independently control chemoreceptor expression. The synthesis of these signals by AWA allows animals to generate sensorimotor responses that reflect the animal's overall state. Our findings suggest a general model in which sensory- and state-dependent transcriptional changes at the sensory periphery modulate animals' sensorimotor responses to meet their ongoing needs and states.
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Affiliation(s)
- Ian G McLachlan
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Talya S Kramer
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
- MIT Biology Graduate Program, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Malvika Dua
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Elizabeth M DiLoreto
- Department of Biology and Biotechnology, Worcester Polytechnic InstituteWorcesterUnited States
| | - Matthew A Gomes
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Ugur Dag
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Jagan Srinivasan
- Department of Biology and Biotechnology, Worcester Polytechnic InstituteWorcesterUnited States
| | - Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
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17
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Ramos CD, Bohnert KA, Johnson AE. Reproductive tradeoffs govern sexually dimorphic tubular lysosome induction in Caenorhabditis elegans. J Exp Biol 2022; 225:jeb244282. [PMID: 35620964 PMCID: PMC9250795 DOI: 10.1242/jeb.244282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/23/2022] [Indexed: 11/20/2022]
Abstract
Sex-specific differences in animal behavior commonly reflect unique reproductive interests. In the nematode Caenorhabditis elegans, hermaphrodites can reproduce without a mate and thus prioritize feeding to satisfy the high energetic costs of reproduction. However, males, which must mate to reproduce, sacrifice feeding to prioritize mate-searching behavior. Here, we demonstrate that these behavioral differences influence sexual dimorphism at the organelle level; young males raised on a rich food source show constitutive induction of gut tubular lysosomes, a non-canonical lysosome morphology that forms in the gut of hermaphrodites when food is limited or as animals age. We found that constitutive induction of gut tubular lysosomes in males results from self-imposed dietary restriction through DAF-7/TGFβ, which promotes exploratory behavior. In contrast, age-dependent induction of gut tubular lysosomes in hermaphrodites is stimulated by self-fertilization activity. Thus, separate reproductive tradeoffs influence tubular lysosome induction in each sex, potentially supporting different requirements for reproductive success.
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Affiliation(s)
| | - K. Adam Bohnert
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Alyssa E. Johnson
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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18
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Kim D, Kim B. Anatomical and Functional Differences in the Sex-Shared Neurons of the Nematode C. elegans. Front Neuroanat 2022; 16:906090. [PMID: 35601998 PMCID: PMC9121059 DOI: 10.3389/fnana.2022.906090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/20/2022] [Indexed: 11/13/2022] Open
Abstract
Studies on sexual dimorphism in the structure and function of the nervous system have been pivotal to understanding sex differences in behavior. Such studies, especially on invertebrates, have shown the importance of neurons specific to one sex (sex-specific neurons) in shaping sexually dimorphic neural circuits. Nevertheless, recent studies using the nematode C. elegans have revealed that the common neurons that exist in both sexes (sex-shared neurons) also play significant roles in generating sex differences in the structure and function of neural circuits. Here, we review the anatomical and functional differences in the sex-shared neurons of C. elegans. These sexually dimorphic characteristics include morphological differences in neurite projection or branching patterns with substantial changes in synaptic connectivity, differences in synaptic connections without obvious structural changes, and functional modulation in neural circuits with no or minimal synaptic connectivity changes. We also cover underlying molecular mechanisms whereby these sex-shared neurons contribute to the establishment of sexually dimorphic circuits during development and function differently between the sexes.
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19
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Flavell SW, Gordus A. Dynamic functional connectivity in the static connectome of Caenorhabditis elegans. Curr Opin Neurobiol 2022; 73:102515. [PMID: 35183877 PMCID: PMC9621599 DOI: 10.1016/j.conb.2021.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/16/2021] [Accepted: 12/22/2021] [Indexed: 01/01/2023]
Abstract
A hallmark of adaptive behavior is the ability to flexibly respond to sensory cues. To understand how neural circuits implement this flexibility, it is critical to resolve how a static anatomical connectome can be modulated such that functional connectivity in the network can be dynamically regulated. Here, we review recent work in the roundworm Caenorhabditis elegans on this topic. EM studies have mapped anatomical connectomes of many C. elegans animals, highlighting the level of stereotypy in the anatomical network. Brain-wide calcium imaging and studies of specified neural circuits have uncovered striking flexibility in the functional coupling of neurons. The coupling between neurons is controlled by neuromodulators that act over long timescales. This gives rise to persistent behavioral states that animals switch between, allowing them to generate adaptive behavioral responses across environmental conditions. Thus, the dynamic coupling of neurons enables multiple behavioral states to be encoded in a physically stereotyped connectome.
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Affiliation(s)
- Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Andrew Gordus
- Department of Biology, Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
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20
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Wan ZY, Lin VCL, Hua YG. Pomc Plays an Important Role in Sexual Size Dimorphism in Tilapia. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2021; 23:201-214. [PMID: 33580373 DOI: 10.1007/s10126-020-10015-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 12/27/2020] [Indexed: 06/12/2023]
Abstract
Sexual dimorphism is common across the animal kingdom. Knowledge of the mechanisms of sexual size dimorphism is limited although it is important in biology and aquaculture. Tilapia is the common name for ~ 100 species of cichlid fish. Some are important aquaculture species and males outgrow females. To gain novel insights into the mechanisms underlying sexual size dimorphism, we analyzed the differences of brain transcriptomes between males and females in Mozambique tilapia and studied the function of the pro-opiomelanocortin (Pomc) gene in tilapia and zebrafish. The transcriptome analysis identified 123, 55, and 2706 sex-biased genes at 5, 30, and 90 dph (days post-hatch), respectively, indicating sexual dimorphism of gene expressions in the brain. The expression of Pomc in the tilapia brain was a female-biased at 30, 90, and 120 dph. An analysis of the DNA sequence located upstream of the tilapia Pomc transcriptional start site identified two estrogenic response elements. In vitro luciferase assay of the two elements revealed that β-estradiol significantly enhanced the expression of luciferase activity, suggesting that the expression of Pomc is mediated by estrogen. We knocked out Pomc in zebrafish using Crispr/Cas-9. The Pomc-knockout zebrafish showed faster growth and higher sensitivity to feeding as compared to the wild-type fish. Taken together, our results indicate that Pomc contributes to sexual size dimorphism and suggest that the high estrogen level in females promotes the expression of Pomc and suppresses feeding in female tilapias, which leads to the slower growth of female tilapias.
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Affiliation(s)
- Z Y Wan
- Molecular Population Genetics and Breeding Group, Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, 117604, Singapore
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - V C L Lin
- Molecular Population Genetics and Breeding Group, Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, 117604, Singapore.
| | - Yue Gen Hua
- Molecular Population Genetics and Breeding Group, Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, 117604, Singapore.
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore.
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21
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Molina-García L, Lloret-Fernández C, Cook SJ, Kim B, Bonnington RC, Sammut M, O'Shea JM, Gilbert SPR, Elliott DJ, Hall DH, Emmons SW, Barrios A, Poole RJ. Direct glia-to-neuron transdifferentiation gives rise to a pair of male-specific neurons that ensure nimble male mating. eLife 2020; 9:e48361. [PMID: 33138916 PMCID: PMC7609048 DOI: 10.7554/elife.48361] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/02/2020] [Indexed: 12/20/2022] Open
Abstract
Sexually dimorphic behaviours require underlying differences in the nervous system between males and females. The extent to which nervous systems are sexually dimorphic and the cellular and molecular mechanisms that regulate these differences are only beginning to be understood. We reveal here a novel mechanism by which male-specific neurons are generated in Caenorhabditis elegans through the direct transdifferentiation of sex-shared glial cells. This glia-to-neuron cell fate switch occurs during male sexual maturation under the cell-autonomous control of the sex-determination pathway. We show that the neurons generated are cholinergic, peptidergic, and ciliated putative proprioceptors which integrate into male-specific circuits for copulation. These neurons ensure coordinated backward movement along the mate's body during mating. One step of the mating sequence regulated by these neurons is an alternative readjustment movement performed when intromission becomes difficult to achieve. Our findings reveal programmed transdifferentiation as a developmental mechanism underlying flexibility in innate behaviour.
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Affiliation(s)
- Laura Molina-García
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Carla Lloret-Fernández
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Steven J Cook
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineNew YorkUnited States
| | - Byunghyuk Kim
- Department of Genetics, Albert Einstein College of MedicineNew YorkUnited States
| | - Rachel C Bonnington
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Michele Sammut
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Jack M O'Shea
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Sophie PR Gilbert
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - David J Elliott
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - David H Hall
- Department of Genetics, Albert Einstein College of MedicineNew YorkUnited States
| | - Scott W Emmons
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineNew YorkUnited States
- Department of Genetics, Albert Einstein College of MedicineNew YorkUnited States
| | - Arantza Barrios
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Richard J Poole
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
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22
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Bayer EA, Stecky RC, Neal L, Katsamba PS, Ahlsen G, Balaji V, Hoppe T, Shapiro L, Oren-Suissa M, Hobert O. Ubiquitin-dependent regulation of a conserved DMRT protein controls sexually dimorphic synaptic connectivity and behavior. eLife 2020; 9:59614. [PMID: 33021200 PMCID: PMC7538159 DOI: 10.7554/elife.59614] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/05/2020] [Indexed: 12/20/2022] Open
Abstract
Sex-specific synaptic connectivity is beginning to emerge as a remarkable, but little explored feature of animal brains. We describe here a novel mechanism that promotes sexually dimorphic neuronal function and synaptic connectivity in the nervous system of the nematode Caenorhabditis elegans. We demonstrate that a phylogenetically conserved, but previously uncharacterized Doublesex/Mab-3 related transcription factor (DMRT), dmd-4, is expressed in two classes of sex-shared phasmid neurons specifically in hermaphrodites but not in males. We find dmd-4 to promote hermaphrodite-specific synaptic connectivity and neuronal function of phasmid sensory neurons. Sex-specificity of DMD-4 function is conferred by a novel mode of posttranslational regulation that involves sex-specific protein stabilization through ubiquitin binding to a phylogenetically conserved but previously unstudied protein domain, the DMA domain. A human DMRT homolog of DMD-4 is controlled in a similar manner, indicating that our findings may have implications for the control of sexual differentiation in other animals as well.
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Affiliation(s)
- Emily A Bayer
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Rebecca C Stecky
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Lauren Neal
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Phinikoula S Katsamba
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
| | - Goran Ahlsen
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
| | - Vishnu Balaji
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
| | - Meital Oren-Suissa
- Weizmann Institute of Science, Department of Neurobiology, Rehovot, Israel
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
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23
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Salzberg Y, Gat A, Oren-Suissa M. One template, two outcomes: How does the sex-shared nervous system generate sex-specific behaviors? Curr Top Dev Biol 2020; 144:245-268. [PMID: 33992155 DOI: 10.1016/bs.ctdb.2020.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Sex-specific behaviors are common in nature and are crucial for reproductive fitness and species survival. A key question in the field of sex/gender neurobiology is whether and to what degree the sex-shared nervous system differs between the sexes in the anatomy, connectivity and molecular identity of its components. An equally intriguing issue is how does the same sex-shared neuronal template diverge to mediate distinct behavioral outputs in females and males. This chapter aims to present the most up-to-date understanding of how this task is achieved in C. elegans. The vast majority of neurons in C. elegans are shared among the two sexes in terms of their lineage history, anatomical position and neuronal identity. Yet a substantial amount of evidence points to the hermaphrodite-male counterparts of some neurons expressing different genes and forming different synaptic connections. This, in turn, enables the same cells and circuits to transmit discrete signals in the two sexes and ultimately execute different functions. We review the various sex-shared behavioral paradigms that have been shown to be sexually dimorphic in recent years, discuss the mechanisms that underlie these examples, refer to the developmental regulation of neuronal dimorphism and suggest evolutionary concepts that emerge from the data.
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Affiliation(s)
- Yehuda Salzberg
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Asaf Gat
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Meital Oren-Suissa
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
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24
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Abstract
Microbes are ubiquitous in the natural environment of Caenorhabditis elegans. Bacteria serve as a food source for C. elegans but may also cause infection in the nematode host. The sensory nervous system of C. elegans detects diverse microbial molecules, ranging from metabolites produced by broad classes of bacteria to molecules synthesized by specific strains of bacteria. Innate recognition through chemosensation of bacterial metabolites or mechanosensation of bacteria can induce immediate behavioral responses. The ingestion of nutritive or pathogenic bacteria can modulate internal states that underlie long-lasting behavioral changes. Ingestion of nutritive bacteria leads to learned attraction and exploitation of the bacterial food source. Infection, which is accompanied by activation of innate immunity, stress responses, and host damage, leads to the development of aversive behavior. The integration of a multitude of microbial sensory cues in the environment is shaped by experience and context. Genetic, chemical, and neuronal studies of C. elegans behavior in the presence of bacteria have defined neural circuits and neuromodulatory systems that shape innate and learned behavioral responses to microbial cues. These studies have revealed the profound influence that host-microbe interactions have in governing the behavior of this simple animal host.
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Affiliation(s)
- Dennis H Kim
- Division of Infectious Diseases, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Steven W Flavell
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
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25
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Park J, Meisel JD, Kim DH. Immediate activation of chemosensory neuron gene expression by bacterial metabolites is selectively induced by distinct cyclic GMP-dependent pathways in Caenorhabditis elegans. PLoS Genet 2020; 16:e1008505. [PMID: 32776934 PMCID: PMC7416920 DOI: 10.1371/journal.pgen.1008505] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 06/15/2020] [Indexed: 01/19/2023] Open
Abstract
Dynamic gene expression in neurons shapes fundamental processes in the nervous systems of animals. However, how neuronal activation by different stimuli can lead to distinct transcriptional responses is not well understood. We have been studying how microbial metabolites modulate gene expression in chemosensory neurons of Caenorhabditis elegans. Considering the diverse environmental stimuli that can activate chemosensory neurons of C. elegans, we sought to understand how specific transcriptional responses can be generated in these neurons in response to distinct cues. We have focused on the mechanism of rapid (<6 min) and selective transcriptional induction of daf-7, a gene encoding a TGF-β ligand, in the ASJ chemosensory neurons in response to the pathogenic bacterium Pseudomonas aeruginosa. DAF-7 is required for the protective behavioral avoidance of P. aeruginosa by C. elegans. Here, we define the involvement of two distinct cyclic GMP (cGMP)-dependent pathways that are required for daf-7 expression in the ASJ neuron pair in response to P. aeruginosa. We show that a calcium-independent pathway dependent on the cGMP-dependent protein kinase G (PKG) EGL-4, and a canonical calcium-dependent signaling pathway dependent on the activity of a cyclic nucleotide-gated channel subunit CNG-2, function in parallel to activate rapid, selective transcription of daf-7 in response to P. aeruginosa metabolites. Our data suggest that fast, selective early transcription of neuronal genes require PKG in shaping responses to distinct microbial stimuli in a pair of C. elegans chemosensory neurons.
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Affiliation(s)
- Jaeseok Park
- Division of Infectious Diseases, Boston Children’s Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Joshua D. Meisel
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Dennis H. Kim
- Division of Infectious Diseases, Boston Children’s Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
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26
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Lawson HN, Wexler LR, Wnuk HK, Portman DS. Dynamic, Non-binary Specification of Sexual State in the C. elegans Nervous System. Curr Biol 2020; 30:3617-3623.e3. [PMID: 32707065 DOI: 10.1016/j.cub.2020.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 12/21/2022]
Abstract
Biological sex in animals is often considered a fixed, individual-level characteristic. However, not all sex-specific features are static: for example, C. elegans males (XO) can sometimes exhibit hermaphrodite (XX)-like feeding behavior [1, 2]. (C. elegans hermaphrodites are somatic females that transiently produce self-sperm.) Essentially all somatic sex differences in C. elegans are governed by the master regulator tra-1, whose activity is controlled by chromosomal sex and is necessary and sufficient to specify the hermaphrodite state [3]. One aspect of this state is high expression of the chemoreceptor odr-10. In hermaphrodites, high odr-10 expression promotes feeding, but in males, low odr-10 expression facilitates exploration [4]. However, males suppress this sex difference in two contexts: juvenile males exhibit high odr-10 expression and food deprivation activates odr-10 in adult males [4-6]. Remarkably, we find that both of these phenomena require tra-1. In juvenile (L3) males, tra-1 is expressed in numerous neurons; this expression diminishes as individuals mature into adulthood, a process that requires conserved regulators of sexual maturation. tra-1 remains expressed in a small number of neurons in adult males, where it likely has a permissive role in odr-10 activation. Thus, the neuronal functions of tra-1 are not limited to hermaphrodites; rather, tra-1 also acts in the male nervous system to transiently suppress a sexual dimorphism, developmentally and in response to nutritional stress. Our results show that the molecular and functional representation of sexual state in C. elegans is neither static nor homogeneous, challenging traditional notions about the nature of biological sex.
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Affiliation(s)
- Hannah N Lawson
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Leigh R Wexler
- Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA
| | - Hayley K Wnuk
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Douglas S Portman
- Department of Biology, University of Rochester, Rochester, NY, USA; Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA; Ernest J. Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY, USA.
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C. elegans Males Integrate Food Signals and Biological Sex to Modulate State-Dependent Chemosensation and Behavioral Prioritization. Curr Biol 2020; 30:2695-2706.e4. [PMID: 32531276 DOI: 10.1016/j.cub.2020.05.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 04/15/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022]
Abstract
Dynamic integration of internal and external cues is essential for flexible, adaptive behavior. In C. elegans, biological sex and feeding state regulate expression of the food-associated chemoreceptor odr-10, contributing to plasticity in food detection and the decision between feeding and exploration. In adult hermaphrodites, odr-10 expression is high, but in well-fed adult males, odr-10 expression is low, promoting exploratory mate-searching behavior. Food-deprivation transiently activates male odr-10 expression, heightening food sensitivity and reducing food leaving. Here, we identify a neuroendocrine feedback loop that sex-specifically regulates odr-10 in response to food deprivation. In well-fed males, insulin-like (insulin/IGF-1 signaling [IIS]) and transforming growth factor β (TGF-β) signaling repress odr-10 expression. Upon food deprivation, odr-10 is directly activated by DAF-16/FoxO, the canonical C. elegans IIS effector. The TGF-β ligand DAF-7 likely acts upstream of IIS and links feeding to odr-10 only in males, due in part to the male-specific expression of daf-7 in ASJ. Surprisingly, these responses to food deprivation are not triggered by internal metabolic cues but rather by the loss of sensory signals associated with food. When males are starved in the presence of inedible food, they become nutritionally stressed, but odr-10 expression remains low and exploratory behavior is suppressed less than in starved control males. Food signals are detected by a small number of sensory neurons whose activity non-autonomously regulates daf-7 expression, IIS, and odr-10. Thus, adult C. elegans males employ a neuroendocrine feedback loop that integrates food detection and genetic sex to dynamically modulate chemoreceptor expression and influence the feeding-versus-exploration decision.
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Singh J, Aballay A. Intestinal infection regulates behavior and learning via neuroendocrine signaling. eLife 2019; 8:e50033. [PMID: 31674907 PMCID: PMC6884406 DOI: 10.7554/elife.50033] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/31/2019] [Indexed: 12/14/2022] Open
Abstract
The recognition of pathogens and subsequent activation of defense responses are critical for the survival of organisms. The nematode Caenorhabditis elegans recognizes pathogenic bacteria and elicits defense responses by activating immune pathways and pathogen avoidance. Here we show that chemosensation of phenazines produced by pathogenic Pseudomonas aeruginosa, which leads to rapid activation of DAF-7/TGF-β in ASJ neurons, is insufficient for the elicitation of pathogen avoidance behavior. Instead, intestinal infection and bloating of the lumen, which depend on the virulence of P. aeruginosa, regulates both pathogen avoidance and aversive learning by modulating not only the DAF-7/TGF-β pathway but also the G-protein coupled receptor NPR-1 pathway, which also controls aerotaxis behavior. Modulation of these neuroendocrine pathways by intestinal infection serves as a systemic feedback that enables animals to avoid virulent bacteria. These results reveal how feedback from the intestine during infection can modulate the behavior, learning, and microbial perception of the host.
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Affiliation(s)
- Jogender Singh
- Department of Molecular Microbiology & ImmunologyOregon Health & Science UniversityPortlandUnited States
| | - Alejandro Aballay
- Department of Molecular Microbiology & ImmunologyOregon Health & Science UniversityPortlandUnited States
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29
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Whole-animal connectomes of both Caenorhabditis elegans sexes. Nature 2019; 571:63-71. [PMID: 31270481 DOI: 10.1038/s41586-019-1352-7] [Citation(s) in RCA: 379] [Impact Index Per Article: 75.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/28/2019] [Indexed: 01/08/2023]
Abstract
Knowledge of connectivity in the nervous system is essential to understanding its function. Here we describe connectomes for both adult sexes of the nematode Caenorhabditis elegans, an important model organism for neuroscience research. We present quantitative connectivity matrices that encompass all connections from sensory input to end-organ output across the entire animal, information that is necessary to model behaviour. Serial electron microscopy reconstructions that are based on the analysis of both new and previously published electron micrographs update previous results and include data on the male head. The nervous system differs between sexes at multiple levels. Several sex-shared neurons that function in circuits for sexual behaviour are sexually dimorphic in structure and connectivity. Inputs from sex-specific circuitry to central circuitry reveal points at which sexual and non-sexual pathways converge. In sex-shared central pathways, a substantial number of connections differ in strength between the sexes. Quantitative connectomes that include all connections serve as the basis for understanding how complex, adaptive behavior is generated.
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30
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Lawson H, Vuong E, Miller RM, Kiontke K, Fitch DHA, Portman DS. The Makorin lep-2 and the lncRNA lep-5 regulate lin-28 to schedule sexual maturation of the C. elegans nervous system. eLife 2019; 8:e43660. [PMID: 31264582 PMCID: PMC6606027 DOI: 10.7554/elife.43660] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/10/2019] [Indexed: 12/30/2022] Open
Abstract
Sexual maturation must occur on a controlled developmental schedule. In mammals, Makorin3 (MKRN3) and the miRNA regulators LIN28A/B are key regulators of this process, but how they act is unclear. In C. elegans, sexual maturation of the nervous system includes the functional remodeling of postmitotic neurons and the onset of adult-specific behaviors. Here, we find that the lin-28-let-7 axis (the 'heterochronic pathway') determines the timing of these events. Upstream of lin-28, the Makorin lep-2 and the lncRNA lep-5 regulate maturation cell-autonomously, indicating that distributed clocks, not a central timer, coordinate sexual differentiation of the C. elegans nervous system. Overexpression of human MKRN3 delays aspects of C. elegans sexual maturation, suggesting the conservation of Makorin function. These studies reveal roles for a Makorin and a lncRNA in timing of sexual differentiation; moreover, they demonstrate deep conservation of the lin-28-let-7 system in controlling the functional maturation of the nervous system.
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Affiliation(s)
- Hannah Lawson
- Department of BiologyUniversity of RochesterRochesterUnited States
| | - Edward Vuong
- Department of Biomedical GeneticsUniversity of RochesterRochesterUnited States
| | - Renee M Miller
- Department of Brain and Cognitive SciencesUniversity of RochesterRochesterUnited States
| | - Karin Kiontke
- Center for Developmental Genetics, Department of BiologyNew York UniversityNew YorkUnited States
| | - David HA Fitch
- Center for Developmental Genetics, Department of BiologyNew York UniversityNew YorkUnited States
| | - Douglas S Portman
- Department of BiologyUniversity of RochesterRochesterUnited States
- Department of Biomedical GeneticsUniversity of RochesterRochesterUnited States
- Department of NeuroscienceUniversity of RochesterRochesterUnited States
- DelMonte Institute for NeuroscienceUniversity of RochesterRochesterUnited States
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Moore RS, Kaletsky R, Murphy CT. Piwi/PRG-1 Argonaute and TGF-β Mediate Transgenerational Learned Pathogenic Avoidance. Cell 2019; 177:1827-1841.e12. [PMID: 31178117 DOI: 10.1016/j.cell.2019.05.024] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/04/2019] [Accepted: 05/13/2019] [Indexed: 12/17/2022]
Abstract
The ability to inherit learned information from parents could be evolutionarily beneficial, enabling progeny to better survive dangerous conditions. We discovered that, after C. elegans have learned to avoid the pathogenic bacteria Pseudomonas aeruginosa (PA14), they pass this learned behavior on to their progeny, through either the male or female germline, persisting through the fourth generation. Expression of the TGF-β ligand DAF-7 in the ASI sensory neurons correlates with and is required for this transgenerational avoidance behavior. Additionally, the Piwi Argonaute homolog PRG-1 and its downstream molecular components are required for transgenerational inheritance of both avoidance behavior and ASI daf-7 expression. Animals whose parents have learned to avoid PA14 display a PA14 avoidance-based survival advantage that is also prg-1 dependent, suggesting an adaptive response. Transgenerational epigenetic inheritance of pathogenic learning may optimize progeny decisions to increase survival in fluctuating environmental conditions.
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Affiliation(s)
- Rebecca S Moore
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Rachel Kaletsky
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Coleen T Murphy
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ 08544, USA.
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Sanzo-Machuca Á, Monje Moreno JM, Casado-Navarro R, Karakuzu O, Guerrero-Gómez D, Fierro-González JC, Swoboda P, Muñoz MJ, Garsin DA, Pedrajas JR, Barrios A, Miranda-Vizuete A. Redox-dependent and redox-independent functions of Caenorhabditis elegans thioredoxin 1. Redox Biol 2019; 24:101178. [PMID: 30953965 PMCID: PMC6449771 DOI: 10.1016/j.redox.2019.101178] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 03/15/2019] [Accepted: 03/24/2019] [Indexed: 11/19/2022] Open
Abstract
Thioredoxins (TRX) are traditionally considered as enzymes catalyzing redox reactions. However, redox-independent functions of thioredoxins have been described in different organisms, although the underlying molecular mechanisms are yet unknown. We report here the characterization of the first generated endogenous redox-inactive thioredoxin in an animal model, the TRX-1 in the nematode Caenorhabditis elegans. We find that TRX-1 dually regulates the formation of an endurance larval stage (dauer) by interacting with the insulin pathway in a redox-independent manner and the cGMP pathway in a redox-dependent manner. Moreover, the requirement of TRX-1 for the extended longevity of worms with compromised insulin signalling or under calorie restriction relies on TRX-1 redox activity. In contrast, the nuclear translocation of the SKN-1 transcription factor and increased LIPS-6 protein levels in the intestine upon trx-1 deficiency are strictly redox-independent. Finally, we identify a novel function of C. elegans TRX-1 in male food-leaving behaviour that is redox-dependent. Taken together, our results position C. elegans as an ideal model to gain mechanistic insight into the redox-independent functions of metazoan thioredoxins, overcoming the limitations imposed by the embryonic lethal phenotypes of thioredoxin mutants in higher organisms. C. elegans expressing endogenous “redox-dead” TRX-1 are viable. The extended lifespan extension of worm daf-2 and eat-2 mutants and the food-leaving behaviour of C. elegans males requires a redox-active TRX-1. The SKN-1 nuclear translocation and increased lips-6 expression upon TRX-1 deficiency is redox-independent. TRX-1 regulates dauer formation by both redox-dependent and redox-independent mechanisms. C. elegans is an ideal model to interrogate on the molecular mechanisms underlying the redox-independent functions of metazoan thioredoxins.
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Affiliation(s)
- Ángela Sanzo-Machuca
- Redox Homeostasis Group, Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013, Sevilla, Spain
| | | | - Rafael Casado-Navarro
- Redox Homeostasis Group, Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013, Sevilla, Spain; Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK
| | - Ozgur Karakuzu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - David Guerrero-Gómez
- Redox Homeostasis Group, Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013, Sevilla, Spain
| | | | - Peter Swoboda
- Department of Biosciences and Nutrition, Karolinska Institute, 14183, Huddinge, Sweden
| | - Manuel J Muñoz
- Department of Genetics, Universidad Pablo de Olavide, 41013, Seville, Spain
| | - Danielle A Garsin
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - José Rafael Pedrajas
- Grupo de Bioquímica y Señalización Celular, Departamento de Biología Experimental, Universidad de Jaén, 23071, Jaén, Spain
| | - Arantza Barrios
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK
| | - Antonio Miranda-Vizuete
- Redox Homeostasis Group, Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013, Sevilla, Spain.
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Pereira L, Aeschimann F, Wang C, Lawson H, Serrano-Saiz E, Portman DS, Großhans H, Hobert O. Timing mechanism of sexually dimorphic nervous system differentiation. eLife 2019; 8:e42078. [PMID: 30599092 PMCID: PMC6312707 DOI: 10.7554/elife.42078] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 10/24/2018] [Indexed: 12/16/2022] Open
Abstract
The molecular mechanisms that control the timing of sexual differentiation in the brain are poorly understood. We found that the timing of sexually dimorphic differentiation of postmitotic, sex-shared neurons in the nervous system of the Caenorhabditis elegans male is controlled by the temporally regulated miRNA let-7 and its target lin-41, a translational regulator. lin-41 acts through lin-29a, an isoform of a conserved Zn finger transcription factor, expressed in a subset of sex-shared neurons only in the male. Ectopic lin-29a is sufficient to impose male-specific features at earlier stages of development and in the opposite sex. The temporal, sexual and spatial specificity of lin-29a expression is controlled intersectionally through the lin-28/let-7/lin-41 heterochronic pathway, sex chromosome configuration and neuron-type-specific terminal selector transcription factors. Two Doublesex-like transcription factors represent additional sex- and neuron-type specific targets of LIN-41 and are regulated in a similar intersectional manner.
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Affiliation(s)
- Laura Pereira
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Florian Aeschimann
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
- University of BaselBaselSwitzerland
| | - Chen Wang
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Hannah Lawson
- Department of BiologyUniversity of RochesterRochesterUnited States
| | - Esther Serrano-Saiz
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Douglas S Portman
- Department of BiologyUniversity of RochesterRochesterUnited States
- DelMonte Institute for Neuroscience, Department of Biomedical GeneticsUniversity of RochesterNew YorkUnited States
| | - Helge Großhans
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
- University of BaselBaselSwitzerland
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
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34
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Sex-Specific Response of Caenorhabditis elegans to Methylmercury Toxicity. Neurotox Res 2018; 35:208-216. [DOI: 10.1007/s12640-018-9949-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/10/2018] [Accepted: 08/15/2018] [Indexed: 10/28/2022]
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35
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Hilbert ZA, Kim DH. PDF-1 neuropeptide signaling regulates sexually dimorphic gene expression in shared sensory neurons of C. elegans. eLife 2018; 7:36547. [PMID: 30024377 PMCID: PMC6053303 DOI: 10.7554/elife.36547] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/05/2018] [Indexed: 12/23/2022] Open
Abstract
Sexually dimorphic behaviors are a feature common to species across the animal kingdom, however how such behaviors are generated from mostly sex-shared nervous systems is not well understood. Building on our previous work which described the sexually dimorphic expression of a neuroendocrine ligand, DAF-7, and its role in behavioral decision-making in C. elegans (Hilbert and Kim, 2017), we show here that sex-specific expression of daf-7 is regulated by another neuroendocrine ligand, Pigment Dispersing Factor (PDF-1), which has previously been implicated in regulating male-specific behavior (Barrios et al., 2012). Our analysis revealed that PDF-1 signaling acts sex- and cell-specifically in the ASJ neurons to regulate the expression of daf-7, and we show that differences in PDFR-1 receptor activity account for the sex-specific effects of this pathway. Our data suggest that modulation of the sex-shared nervous system by a cascade of neuroendocrine signals can shape sexually dimorphic behaviors.
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Affiliation(s)
- Zoë A Hilbert
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Dennis H Kim
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
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36
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Abstract
The recently determined connectome of the Caenorhabditis elegans adult male, together with the known connectome of the hermaphrodite, opens up the possibility for a comprehensive description of sexual dimorphism in this species and the identification and study of the neural circuits underlying sexual behaviors. The C. elegans nervous system consists of 294 neurons shared by both sexes plus neurons unique to each sex, 8 in the hermaphrodite and 91 in the male. The sex-specific neurons are well integrated within the remainder of the nervous system; in the male, 16% of the input to the shared component comes from male-specific neurons. Although sex-specific neurons are involved primarily, but not exclusively, in controlling sex-unique behavior—egg-laying in the hermaphrodite and copulation in the male—these neurons act together with shared neurons to make navigational choices that optimize reproductive success. Sex differences in general behaviors are underlain by considerable dimorphism within the shared component of the nervous system itself, including dimorphism in synaptic connectivity.
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Affiliation(s)
- Scott W. Emmons
- Department of Genetics and Dominick Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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37
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Emmons SW. Neural Circuitry That Mediates Behavior Governing the Tradeoffs Between Survival and Reproduction in Caenorhabditis elegans. Integr Comp Biol 2018; 57:1161-1165. [PMID: 28992344 DOI: 10.1093/icb/icx077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In all outcrossing sexual species there is a mechanism that brings two parents together. For animals, this reproductive requirement may at times conflict with other needs, such as foraging for food. This tension has been studied using the tiny (1 mm) nematode worm, Caenorhabditis elegans. In a trade off between certainty of survival and possibility of reproduction, the C. elegans male will abandon a food patch lacking mates and explore its environment to find one where mates are present. A quantitative behavioral assay has been used to study the behavioral mechanism of mate searching and nutritional, sexual, and neurohormonal pathways that influence the underlying drive state. Taking advantage of the known connectivity of the C. elegans nervous system, neural pathways have been identified that influence the male's behavior in the presence of food with and without mates.
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Affiliation(s)
- Scott W Emmons
- Department of Genetics and Dominick Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
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38
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Fagan KA, Luo J, Lagoy RC, Schroeder FC, Albrecht DR, Portman DS. A Single-Neuron Chemosensory Switch Determines the Valence of a Sexually Dimorphic Sensory Behavior. Curr Biol 2018; 28:902-914.e5. [PMID: 29526590 PMCID: PMC5862148 DOI: 10.1016/j.cub.2018.02.029] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/11/2018] [Accepted: 02/14/2018] [Indexed: 01/08/2023]
Abstract
Biological sex, a fundamental dimension of internal state, can modulate neural circuits to generate behavioral variation. Understanding how and why circuits are tuned by sex can provide important insights into neural and behavioral plasticity. Here we find that sexually dimorphic behavioral responses to C. elegans ascaroside sex pheromones are implemented by the functional modulation of shared chemosensory circuitry. In particular, the sexual state of a single sensory neuron pair, ADF, determines the nature of an animal's behavioral response regardless of the sex of the rest of the body. Genetic feminization of ADF causes males to be repelled by, rather than attracted to, ascarosides, whereas masculinization of ADF has the opposite effect in hermaphrodites. When ADF is ablated, both sexes are weakly repelled by ascarosides. Genetic sex modulates ADF function by tuning chemosensation: although ADF is functional in both sexes, it detects the ascaroside ascr#3 only in males, a consequence of cell-autonomous action of the master sexual regulator tra-1. This occurs in part through the conserved DM-domain gene mab-3, which promotes the male state of ADF. The sexual modulation of ADF has a key role in reproductive fitness, as feminization or ablation of ADF renders males unable to use ascarosides to locate mates. Our results reveal an economical mechanism in which sex-specific behavioral valence arises through the cell-autonomous regulation of a chemosensory switch by genetic sex, allowing a social cue with salience for both sexes to elicit navigational responses commensurate with the differing needs of each.
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Affiliation(s)
- Kelli A Fagan
- Neuroscience Graduate Program, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14610, USA
| | - Jintao Luo
- Del Monte Institute for Neuroscience, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14610, USA; Center for Neurotherapeutics Development, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14610, USA
| | - Ross C Lagoy
- Department of Biomedical Engineering, Worcester Polytechnic Institute, 60 Prescott Street, Room 4004, Worcester, MA 01605, USA
| | | | - Dirk R Albrecht
- Department of Biomedical Engineering, Worcester Polytechnic Institute, 60 Prescott Street, Room 4004, Worcester, MA 01605, USA
| | - Douglas S Portman
- Del Monte Institute for Neuroscience, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14610, USA; Center for Neurotherapeutics Development, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14610, USA; Departments of Biomedical Genetics, Neuroscience, and Biology, University of Rochester, 601 Elmwood Avenue, Box 645, Rochester, NY 14610, USA.
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Barr MM, García LR, Portman DS. Sexual Dimorphism and Sex Differences in Caenorhabditis elegans Neuronal Development and Behavior. Genetics 2018; 208:909-935. [PMID: 29487147 PMCID: PMC5844341 DOI: 10.1534/genetics.117.300294] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/05/2018] [Indexed: 01/05/2023] Open
Abstract
As fundamental features of nearly all animal species, sexual dimorphisms and sex differences have particular relevance for the development and function of the nervous system. The unique advantages of the nematode Caenorhabditis elegans have allowed the neurobiology of sex to be studied at unprecedented scale, linking ultrastructure, molecular genetics, cell biology, development, neural circuit function, and behavior. Sex differences in the C. elegans nervous system encompass prominent anatomical dimorphisms as well as differences in physiology and connectivity. The influence of sex on behavior is just as diverse, with biological sex programming innate sex-specific behaviors and modifying many other aspects of neural circuit function. The study of these differences has provided important insights into mechanisms of neurogenesis, cell fate specification, and differentiation; synaptogenesis and connectivity; principles of circuit function, plasticity, and behavior; social communication; and many other areas of modern neurobiology.
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Affiliation(s)
- Maureen M Barr
- Department of Genetics, Rutgers University, Piscataway, New Jersey 08854-8082
| | - L Rene García
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, New York 14642
- Department of Neuroscience, University of Rochester, New York 14642
- Department of Biology, University of Rochester, New York 14642
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40
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O’Donnell MP, Chao PH, Kammenga JE, Sengupta P. Rictor/TORC2 mediates gut-to-brain signaling in the regulation of phenotypic plasticity in C. elegans. PLoS Genet 2018; 14:e1007213. [PMID: 29415022 PMCID: PMC5819832 DOI: 10.1371/journal.pgen.1007213] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 02/20/2018] [Accepted: 01/22/2018] [Indexed: 01/03/2023] Open
Abstract
Animals integrate external cues with information about internal conditions such as metabolic state to execute the appropriate behavioral and developmental decisions. Information about food quality and quantity is assessed by the intestine and transmitted to modulate neuronal functions via mechanisms that are not fully understood. The conserved Target of Rapamycin complex 2 (TORC2) controls multiple processes in response to cellular stressors and growth factors. Here we show that TORC2 coordinates larval development and adult behaviors in response to environmental cues and feeding state in the bacterivorous nematode C. elegans. During development, pheromone, bacterial food, and temperature regulate expression of the daf-7 TGF-β and daf-28 insulin-like peptide in sensory neurons to promote a binary decision between reproductive growth and entry into the alternate dauer larval stage. We find that TORC2 acts in the intestine to regulate neuronal expression of both daf-7 and daf-28, which together reflect bacterial-diet dependent feeding status, thus providing a mechanism for integration of food signals with external cues in the regulation of neuroendocrine gene expression. In the adult, TORC2 similarly acts in the intestine to modulate food-regulated foraging behaviors via a PDF-2/PDFR-1 neuropeptide signaling-dependent pathway. We also demonstrate that genetic variation affects food-dependent larval and adult phenotypes, and identify quantitative trait loci (QTL) associated with these traits. Together, these results suggest that TORC2 acts as a hub for communication of feeding state information from the gut to the brain, thereby contributing to modulation of neuronal function by internal state. Decision-making in all animals, including humans, involves weighing available information about the external environment as well as the animals’ internal conditions. Information about the environment is obtained via the sensory nervous system, whereas internal state can be assessed via cues such as levels of hormones or nutrients. How multiple external and internal inputs are processed in the nervous system to drive behavior or development is not fully understood. In this study, we examine how the nematode C. elegans integrates dietary information received by the gut with environmental signals to alter nervous system function. We have found that a signaling complex, called TORC2, acts in the gut to relay nutrition signals to alter hormonal signaling by the nervous system in C. elegans. Altered neuronal signaling in turn affects a food-dependent binary developmental decision in larvae, as well as food-dependent foraging behaviors in adults. Our results provide a mechanism by which animals prioritize specific signals such as feeding status to appropriately alter their development and/or behavior.
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Affiliation(s)
- Michael P. O’Donnell
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA, United States of America
- * E-mail: (MPO); (PS)
| | - Pin-Hao Chao
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA, United States of America
| | - Jan E. Kammenga
- Laboratory of Nematology, Wageningen University and Research, Wageningen, The Netherlands
| | - Piali Sengupta
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA, United States of America
- * E-mail: (MPO); (PS)
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41
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The role of gap junctions in the C. elegans connectome. Neurosci Lett 2017; 695:12-18. [PMID: 28886984 DOI: 10.1016/j.neulet.2017.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/12/2017] [Accepted: 09/01/2017] [Indexed: 10/18/2022]
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Moshe L, Bekker L, Weller A. A Potential Animal Model of Maladaptive Palatable Food Consumption Followed by Delayed Discomfort. Front Neurosci 2017; 11:377. [PMID: 28725176 PMCID: PMC5496947 DOI: 10.3389/fnins.2017.00377] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/19/2017] [Indexed: 11/13/2022] Open
Abstract
Introduction: Binging is the consumption of larger amounts of food in a briefer period of time than would normally be consumed under similar circumstances. Binging requires palatable food (PF) to trigger abnormal eating, probably reflecting gene × environment interactions. In this study we examined the impact of trait binge eating (BE) and its compulsive nature on the conflict between hedonic eating of PF and anticipation of a delayed aversive effect. We used female rats as an animal model similar to other models of BE. A novel aspect of this model in this paper is the use of a delayed internal aversive effect produced by lactose ingestion. Establishing this model will allow us to better understand the nature of the conflict between immediate reward and its delayed aversive implications. We hypothesized that BE prone (BEP) rats will demonstrate maladaptive decision making, presenting higher motivation toward PF even when this is associated with delayed discomfort. Method: (Phase 1) 52 female adult Wistar rats were divided to two eating profiles: resistant and prone binge eaters (BER/BEP) based on intake of liquid PF (Ensure). Next, all subjects underwent a Lactose Conditioning Protocol (LCP) that included 4 h tests, one baseline and 3 conditioning days (Phase 2), in which solid PF (Oreo cookies) was paired with glucose (control-no internal aversive effect) or lactose, dissolved in liquid PF. Index for PF motivation was PF consumption during the 4 h LCP. To test for memory of lactose conditioning, we performed another LCP with glucose only (anticipation, but no actual lactose-induced discomfort), a week after the last conditioning session. Results: Lactose conditioned BEP showed higher motivation toward PF compared to lactose conditioned BER faced with delayed aversive effects. Only lactose conditioned BER rats devaluated the PF over LCP days, indicating an association between PF and abdominal discomfort. In addition, only lactose conditioned BER presented an adaptive dynamic behavior, by varying PF intake according to consequences. Furthermore, solid PF consumption was predicted by binge size of liquid PF, only for lactose conditioned rats. Conclusions: We established an animal model for a common eating conflict in humans using delayed internal aversive unconditional stimuli.
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Affiliation(s)
- Lital Moshe
- Department of Psychology, Bar-Ilan UniversityRamat-Gan, Israel
- Developmental Psychobiology Lab, Gonda Brain Research Center, Bar-Ilan UniversityRamat-Gan, Israel
| | - Liza Bekker
- Developmental Psychobiology Lab, Gonda Brain Research Center, Bar-Ilan UniversityRamat-Gan, Israel
| | - Aron Weller
- Department of Psychology, Bar-Ilan UniversityRamat-Gan, Israel
- Developmental Psychobiology Lab, Gonda Brain Research Center, Bar-Ilan UniversityRamat-Gan, Israel
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Serrano-Saiz E, Pereira L, Gendrel M, Aghayeva U, Bhattacharya A, Howell K, Garcia LR, Hobert O. A Neurotransmitter Atlas of the Caenorhabditis elegans Male Nervous System Reveals Sexually Dimorphic Neurotransmitter Usage. Genetics 2017; 206:1251-1269. [PMID: 28684604 PMCID: PMC5500128 DOI: 10.1534/genetics.117.202127] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/03/2017] [Indexed: 11/18/2022] Open
Abstract
The nervous system of most animals is sexually dimorphic but such dimorphisms are generally poorly mapped on an anatomical, cellular, and molecular level. The adult nervous system of the nematode Caenorhabditis elegans displays a number of clearly defined anatomical sexual dimorphisms, but molecular features of sexually dimorphic neurons remain sparse. In this resource paper, we provide a comprehensive atlas of neurotransmitters used in the nervous system of the male and compare it to that of the hermaphrodite. Among the three major neurotransmitter systems, acetylcholine (ACh) is the most frequently used, followed by glutamate (Glu), and lastly γ-aminobutyric acid (GABA). Many male-specific neurons utilize multiple neurotransmitter systems. Interestingly, we find that neurons that are present in both sexes alter their neurotransmitter usage depending on the sex of the animal. One neuron scales up its usage of ACh, another becomes serotonergic in males, and another one adds a new neurotransmitter (glutamate) to its nonsex-specific transmitter (ACh). In all these cases, neurotransmitter changes are correlated with substantial changes in synaptic connectivity. We assembled the neurotransmitter maps of the male-specific nervous system into a comprehensive atlas that describes the anatomical position of all the neurons of the male-specific nervous system relative to the sex-shared nervous system. We exemplify the usefulness of the neurotransmitter atlas by using it as a tool to define the expression pattern of a synaptic organizer molecule in the male tail. Taken together, the male neurotransmitter atlas provides an entry point for future functional and developmental analysis of the male nervous system.
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Affiliation(s)
- Esther Serrano-Saiz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York 10027
| | - Laura Pereira
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York 10027
| | - Marie Gendrel
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York 10027
| | - Ulkar Aghayeva
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York 10027
| | - Abhishek Bhattacharya
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York 10027
| | - Kelly Howell
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York 10027
| | - L Rene Garcia
- Department of Biology, Texas A&M University, College Station, Texas 77843
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York 10027
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