Neuroligin dependence of social behaviour in Caenorhabditis elegans provides a model to investigate an autism-associated gene

Abstract Autism spectrum disorder (ASD) is characterized by a triad of behavioural impairments including social behaviour. Neuroligin, a trans-synaptic adhesion molecule, has emerged as a penetrant genetic determinant of behavioural traits that signature the neuroatypical behaviours of autism. However, the function of neuroligin in social circuitry and the impact of genetic variation to this gene is not fully understood. Indeed, in animal studies designed to model autism, there remains controversy regarding the role of neuroligin dysfunction in the expression of disrupted social behaviours. The model organism, Caenorhabditis elegans, offers an informative experimental platform to investigate the impact of genetic variants on social behaviour. In a number of paradigms, it has been shown that inter-organismal communication by chemical cues regulates C. elegans social behaviour. We utilize this social behaviour to investigate the effect of autism-associated genetic variants within the social domain of the research domain criteria. We have identified neuroligin as an important regulator of social behaviour and segregate the importance of this gene to the recognition and/or processing of social cues. We also use CRISPR/Cas9 to edit an R-C mutation that mimics a highly penetrant human mutation associated with autism. C. elegans carrying this mutation phenocopy the behavioural dysfunction of a C. elegans neuroligin null mutant, thus confirming its significance in the regulation of animal social biology. This highlights that quantitative behaviour and precision genetic intervention can be used to manipulate discrete social circuits of the worm to provide further insight into complex social behaviour.

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Neuroligin dependence of social behaviour in C. elegans provides a model to investigate an autism associated gene

10.1101/2020.02.03.931592 ◽

2020 ◽

Cited By ~ 2

Author(s):

Helena Rawsthorne ◽

Fernando Calahorro ◽

Emily Feist ◽

Lindy Holden-Dye ◽

Vincent O’Connor ◽

...

Keyword(s):

Genetic Variants ◽

Social Behaviour ◽

Animal Studies ◽

Model Organism ◽

Autism Spectrum ◽

C Elegans ◽

Genetic Intervention ◽

Important Regulator ◽

Human Mutation ◽

The Impact

AbstractAutism spectrum disorder (ASD) is characterised by a triad of behavioural impairments including social behaviour. Neuroligin, a trans-synaptic adhesion molecule, has emerged as a penetrant genetic determinant of behavioural traits that signature the neuroatypical behaviours of autism. However, the function of neuroligin in social circuitry and the impact of genetic variation to this gene is not fully understood. Indeed, in animal studies designed to model autism there remains controversy regarding the role of neuroligin dysfunction in the expression of disrupted social behaviours. The model organism, C. elegans, offers an informative experimental platform to investigate the impact of genetic variants on social behaviour. In a number of paradigms it has been shown that inter-organismal communication by chemical cues regulates C. elegans social behaviour. We utilise this social behaviour to investigate the effect of autism associated genetic variants within the social domain of the research domain criteria. We have identified neuroligin as an important regulator of social behaviour and segregate the importance of this gene to the recognition and/or processing of social cues. We also use CRISPR/Cas9 to edit an R-C mutation that mimics a highly penetrant human mutation associated with autism. C. elegans carrying this mutation phenocopy the behavioural dysfunction of a C. elegans neuroligin null mutant, thus confirming its significance in the regulation of animal social biology. This highlights that quantitative behaviour and precision genetic intervention can be used to manipulate discrete social circuits of the worm to provide further insight to complex social behaviour.

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The Anthelmintic Quassinoids Ailanthone and Bruceine a Induce Infertility in the Model Organism Caenorhabditis elegans by an Apoptosis-like Mechanism Induced in Gonadal and Spermathecal Tissues

Molecules ◽

10.3390/molecules26237354 ◽

2021 ◽

Vol 26 (23) ◽

pp. 7354

Author(s):

Nicola Knetzger ◽

Viktoria Bachtin ◽

Susanne Lehmann ◽

Andreas Hensel ◽

Eva Liebau ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Model Organism ◽

Epifluorescence Microscopy ◽

Acridine Orange Staining ◽

C Elegans ◽

Reproductive Tissues ◽

Tissue Identification ◽

Membrane Morphology ◽

The Impact ◽

First Time

In continuation of the search for new anthelmintic natural products, the study at hand investigated the nematicidal effects of the two naturally occurring quassinoids ailanthone and bruceine A against the reproductive system of the model nematode Caenorhabditis elegans to pinpoint their anthelmintic mode of action by the application of various microscopic techniques. Differential Interference Contrast (DIC) and the epifluorescence microscopy experiments used in the presented study indicated the genotoxic effects of the tested quassinoids (c ailanthone = 50 µM, c bruceine A = 100 µM) against the nuclei of the investigated gonadal and spermathecal tissues, leaving other morphological key features such as enterocytes or body wall muscle cells unimpaired. In order to gain nanoscopic insight into the morphology of the gonads as well as the considerably smaller spermathecae of C. elegans, an innovative protocol of polyethylene glycol embedding, ultra-sectioning, acridine orange staining, tissue identification by epifluorescence, and subsequent AFM-based ultrastructural data acquisition was applied. This sequence allowed the facile and fast assessment of the impact of quassinoid treatment not only on the gonadal but also on the considerably smaller spermathecal tissues of C. elegans. These first-time ultrastructural investigations on C. elegans gonads and spermathecae by AFM led to the identification of specific quassinoid-induced alterations to the nuclei of the reproductive tissues (e.g., highly condensed chromatin, impaired nuclear membrane morphology, as well as altered nucleolus morphology), altogether implying an apoptosis-like effect of ailanthone and bruceine A on the reproductive tissues of C. elegans.

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Investigating autism associated genes in C. elegans reveals candidates with a role in social behaviour

10.1101/2020.10.02.311506 ◽

2020 ◽

Author(s):

Helena Rawsthorne ◽

Fernando Calahorro ◽

Lindy Holden-Dye ◽

Vincent O’ Connor ◽

James Dillon

Keyword(s):

Social Behaviour ◽

Neurodevelopmental Disorder ◽

Cell Signalling ◽

Model Organism ◽

Phospholipid Metabolism ◽

Autism Spectrum ◽

Genetic Determinants ◽

C Elegans ◽

Gene Database ◽

Experimental Approaches

AbstractAutism spectrum disorder (ASD) is a neurodevelopmental disorder characterised by a triad of behavioural impairments and includes disruption in social behaviour. ASD has a clear genetic underpinning and hundreds of genes are implicated in its aetiology. However, how single penetrant genes disrupt activity of neural circuits which lead to affected behaviours is only beginning to be understood and less is known about how low penetrant genes interact to disrupt emergent behaviours. Investigations are well served by experimental approaches that allow tractable investigation of the underpinning genetic basis of circuits that control behaviours that operate in the biological domains that are neuro-atypical in autism. The model organism C. elegans provides an experimental platform to investigate the effect of genetic mutations on behavioural outputs including those that impact social biology. Here we use progeny-derived social cues that modulate C. elegans food leaving to assay genetic determinants of social behaviour. We used the SAFRI Gene database to identify C. elegans orthologues of human ASD associated genes. We identified a number of mutants that displayed selective deficits in response to progeny. The genetic determinants of this complex social behaviour highlight the important contribution of synaptopathy and implicates genes within cell signalling, epigenetics and phospholipid metabolism functional domains. The approach overlaps with a growing number of studies that investigate potential molecular determinants of autism in C. elegans. However, our use of a complex, sensory integrative, emergent behaviour provides routes to enrich new or underexplored biology with the identification of novel candidate genes with a definable role in social behaviour.

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Investigating autism associated genes in C. elegans reveals candidates with a role in social behaviour

PLoS ONE ◽

10.1371/journal.pone.0243121 ◽

2021 ◽

Vol 16 (5) ◽

pp. e0243121

Author(s):

Helena Rawsthorne ◽

Fernando Calahorro ◽

Lindy Holden-Dye ◽

Vincent O’ Connor ◽

James Dillon

Keyword(s):

Social Behaviour ◽

Neurodevelopmental Disorder ◽

Cell Signalling ◽

Model Organism ◽

Phospholipid Metabolism ◽

Autism Spectrum ◽

Genetic Determinants ◽

C Elegans ◽

Gene Database ◽

Experimental Approaches

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterised by a triad of behavioural impairments and includes disruption in social behaviour. ASD has a clear genetic underpinning and hundreds of genes are implicated in its aetiology. However, how single penetrant genes disrupt activity of neural circuits which lead to affected behaviours is only beginning to be understood and less is known about how low penetrant genes interact to disrupt emergent behaviours. Investigations are well served by experimental approaches that allow tractable investigation of the underpinning genetic basis of circuits that control behaviours that operate in the biological domains that are neuro-atypical in autism. The model organism C. elegans provides an experimental platform to investigate the effect of genetic mutations on behavioural outputs including those that impact social biology. Here we use progeny-derived social cues that modulate C. elegans food leaving to assay genetic determinants of social behaviour. We used the SAFRI Gene database to identify C. elegans orthologues of human ASD associated genes. We identified a number of mutants that displayed selective deficits in response to progeny. The genetic determinants of this complex social behaviour highlight the important contribution of synaptopathy and implicates genes within cell signalling, epigenetics and phospholipid metabolism functional domains. The approach overlaps with a growing number of studies that investigate potential molecular determinants of autism in C. elegans. However, our use of a complex, sensory integrative, emergent behaviour provides routes to enrich new or underexplored biology with the identification of novel candidate genes with a definable role in social behaviour.

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Behavioral Effects of Volatile Anesthetics in Caenorhabditis elegans

Anesthesiology ◽

10.1097/00000542-199610000-00027 ◽

1996 ◽

Vol 85 (4) ◽

pp. 901-912 ◽

Cited By ~ 38

Author(s):

Michael C. Crowder ◽

Laynie D. Shebester ◽

Tim Schedl

Keyword(s):

Nervous System ◽

Caenorhabditis Elegans ◽

Time Course ◽

Model Organism ◽

Volatile Anesthetic ◽

Volatile Anesthetics ◽

Effective Concentration ◽

Forward Genetics ◽

C Elegans ◽

Median Effective Concentration

Background The nematode Caenorhabditis elegans offers many advantages as a model organism for studying volatile anesthetic actions. It has a simple, well-understood nervous system; it allows the researcher to do forward genetics; and its genome will soon be completely sequenced. C. elegans is immobilized by volatile anesthetics only at high concentrations and with an unusually slow time course. Here other behavioral dysfunctions are considered as anesthetic endpoints in C. elegans. Methods The potency of halothane for disrupting eight different behaviors was determined by logistic regression of concentration and response data. Other volatile anesthetics were also tested for some behaviors. Established protocols were used for behavioral endpoints that, except for pharyngeal pumping, were set as complete disruption of the behavior. Time courses were measured for rapid behaviors. Recovery from exposure to 1 or 4 vol% halothane was determined for mating, chemotaxis, and gross movement. All experiments were performed at 20 to 22 degrees C. Results The median effective concentration values for halothane inhibition of mating (0.30 vol%-0.21 mM), chemotaxis (0.34 vol%-0.24 mM), and coordinated movement (0.32 vol% - 0.23 mM) were similar to the human minimum alveolar concentration (MAC; 0.21 mM). In contrast, halothane produced immobility with a median effective concentration of 3.65 vol% (2.6 mM). Other behaviors had intermediate sensitivities. Halothane's effects reached steady-state in 10 min for all behaviors tested except immobility, which required 2 h. Recovery was complete after exposure to 1 vol% halothane but was significantly reduced after exposure to immobilizing concentrations. Conclusions Volatile anesthetics selectively disrupt C. elegans behavior. The potency, time course, and recovery characteristics of halothane's effects on three behaviors are similar to its anesthetic properties in vertebrates. The affected nervous system molecules may express structural motifs similar to those on vertebrate anesthetic targets.

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Stochastic left–right neuronal asymmetry in Caenorhabditis elegans

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2015.0407 ◽

2016 ◽

Vol 371 (1710) ◽

pp. 20150407 ◽

Cited By ~ 16

Author(s):

Amel Alqadah ◽

Yi-Wen Hsieh ◽

Rui Xiong ◽

Chiou-Fen Chuang

Keyword(s):

Caenorhabditis Elegans ◽

Molecular Mechanisms ◽

Neurological Diseases ◽

Calcium Signalling ◽

Model Organism ◽

Brain Asymmetry ◽

C Elegans ◽

Left And Right ◽

Left Right Asymmetry ◽

Neuronal Asymmetry

Left–right asymmetry in the nervous system is observed across species. Defects in left–right cerebral asymmetry are linked to several neurological diseases, but the molecular mechanisms underlying brain asymmetry in vertebrates are still not very well understood. The Caenorhabditis elegans left and right amphid wing ‘C’ (AWC) olfactory neurons communicate through intercellular calcium signalling in a transient embryonic gap junction neural network to specify two asymmetric subtypes, AWC OFF (default) and AWC ON (induced), in a stochastic manner. Here, we highlight the molecular mechanisms that establish and maintain stochastic AWC asymmetry. As the components of the AWC asymmetry pathway are highly conserved, insights from the model organism C. elegans may provide a window onto how brain asymmetry develops in humans. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’.

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An Evolutionarily Conserved Pathway Essential for Orsay Virus Infection of Caenorhabditis elegans

mBio ◽

10.1128/mbio.00940-17 ◽

2017 ◽

Vol 8 (5) ◽

Cited By ~ 13

Author(s):

Hongbing Jiang ◽

Kevin Chen ◽

Luis E. Sandoval ◽

Christian Leung ◽

David Wang

Keyword(s):

Caenorhabditis Elegans ◽

Virus Infection ◽

Tyrosine Kinase ◽

Model Organism ◽

Wiskott Aldrich Syndrome ◽

C Elegans ◽

Evolutionarily Conserved ◽

Conserved Genes ◽

Orsay Virus ◽

Syndrome Protein

ABSTRACT Many fundamental biological discoveries have been made in Caenorhabditis elegans. The discovery of Orsay virus has enabled studies of host-virus interactions in this model organism. To identify host factors critical for Orsay virus infection, we designed a forward genetic screen that utilizes a virally induced green fluorescent protein (GFP) reporter. Following chemical mutagenesis, two Viro (virus induced reporter off) mutants that failed to express GFP were mapped to sid-3, a nonreceptor tyrosine kinase, and B0280.13 (renamed viro-2), an ortholog of human Wiskott-Aldrich syndrome protein (WASP). Both mutants yielded Orsay virus RNA levels comparable to that of the residual input virus, suggesting that they are not permissive for Orsay virus replication. In addition, we demonstrated that both genes affect an early prereplication stage of Orsay virus infection. Furthermore, it is known that the human ortholog of SID-3, activated CDC42-associated kinase (ACK1/TNK2), is capable of phosphorylating human WASP, suggesting that VIRO-2 may be a substrate for SID-3 in C. elegans. A targeted RNA interference (RNAi) knockdown screen further identified the C. elegans gene nck-1, which has a human ortholog that interacts with TNK2 and WASP, as required for Orsay virus infection. Thus, genetic screening in C. elegans identified critical roles in virus infection for evolutionarily conserved genes in a known human pathway. IMPORTANCE Orsay virus is the only known virus capable of naturally infecting the model organism Caenorhabditis elegans, which shares many evolutionarily conserved genes with humans. We exploited the robust genetic tractability of C. elegans to identify three host genes, sid-3, viro-2, and nck-1, which are essential for Orsay virus infection. Mutant animals that lack these three genes are highly defective in viral replication. Strikingly, the human orthologs of these three genes, activated CDC42-associated kinase (TNK2), Wiskott-Aldrich syndrome protein (WASP), and noncatalytic region of tyrosine kinase adaptor protein 1 (NCK1) are part of a known signaling pathway in mammals. These results suggest that TNK2, WASP, and NCK1 may play important roles in mammalian virus infection. IMPORTANCE Orsay virus is the only known virus capable of naturally infecting the model organism Caenorhabditis elegans, which shares many evolutionarily conserved genes with humans. We exploited the robust genetic tractability of C. elegans to identify three host genes, sid-3, viro-2, and nck-1, which are essential for Orsay virus infection. Mutant animals that lack these three genes are highly defective in viral replication. Strikingly, the human orthologs of these three genes, activated CDC42-associated kinase (TNK2), Wiskott-Aldrich syndrome protein (WASP), and noncatalytic region of tyrosine kinase adaptor protein 1 (NCK1) are part of a known signaling pathway in mammals. These results suggest that TNK2, WASP, and NCK1 may play important roles in mammalian virus infection.

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Caenorhabditis elegans as a Model Organism to Evaluate the Antioxidant Effects of Phytochemicals

Molecules ◽

10.3390/molecules25143194 ◽

2020 ◽

Vol 25 (14) ◽

pp. 3194

Author(s):

Begoña Ayuda-Durán ◽

Susana González-Manzano ◽

Ana M. González-Paramás ◽

Celestino Santos-Buelga

Keyword(s):

Oxidative Stress ◽

Caenorhabditis Elegans ◽

Model Organism ◽

Lipid Peroxides ◽

Biological Research ◽

Loss Of Function ◽

Fluorescent Reporters ◽

C Elegans ◽

High Degree

The nematode Caenorhabditis elegans was introduced as a model organism in biological research by Sydney Brenner in the 1970s. Since then, it has been increasingly used for investigating processes such as ageing, oxidative stress, neurodegeneration, or inflammation, for which there is a high degree of homology between C. elegans and human pathways, so that the worm offers promising possibilities to study mechanisms of action and effects of phytochemicals of foods and plants. In this paper, the genes and pathways regulating oxidative stress in C. elegans are discussed, as well as the methodological approaches used for their evaluation in the worm. In particular, the following aspects are reviewed: the use of stress assays, determination of chemical and biochemical markers (e.g., ROS, carbonylated proteins, lipid peroxides or altered DNA), influence on gene expression and the employment of mutant worm strains, either carrying loss-of-function mutations or fluorescent reporters, such as the GFP.

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Caenorhabditis elegans as an Emerging Model for Virus-Host Interactions

Journal of Virology ◽

10.1128/jvi.00509-17 ◽

2017 ◽

Vol 91 (23) ◽

Cited By ~ 10

Author(s):

Don B. Gammon

Keyword(s):

Caenorhabditis Elegans ◽

Virus Infection ◽

Fungal Pathogens ◽

Model Organism ◽

Artificial Infection ◽

Viral Pathogen ◽

Content Type ◽

Host Interactions ◽

C Elegans ◽

Infection Models

ABSTRACT Since 1999, Caenorhabditis elegans has been extensively used to study microbe-host interactions due to its simple culture, genetic tractability, and susceptibility to numerous bacterial and fungal pathogens. In contrast, virus studies have been hampered by a lack of convenient virus infection models in nematodes. The recent discovery of a natural viral pathogen of C. elegans and development of diverse artificial infection models are providing new opportunities to explore virus-host interplay in this powerful model organism.

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Hydrogen Peroxide-Mediated Killing of Caenorhabditis elegans by Streptococcus pyogenes

Infection and Immunity ◽

10.1128/iai.70.9.5202-5207.2002 ◽

2002 ◽

Vol 70 (9) ◽

pp. 5202-5207 ◽

Cited By ~ 65

Author(s):

W. T. M. Jansen ◽

M. Bolm ◽

R. Balling ◽

G. S. Chhatwal ◽

R. Schnabel

Keyword(s):

Hydrogen Peroxide ◽

Caenorhabditis Elegans ◽

Streptococcus Pyogenes ◽

Wide Spectrum ◽

Model Organism ◽

Common Mechanism ◽

Gram Positive ◽

C Elegans ◽

Gram Positive Bacteria ◽

Serovar Typhimurium

ABSTRACT Caenorhabditis elegans is currently introduced as a new, facile, and cheap model organism to study the pathogenesis of gram-negative bacteria such as Pseudomonas aeruginosa and Salmonella enterica serovar Typhimurium. The mechanisms of killing involve either diffusible exotoxins or infection-like processes. Recently, it was shown that also some gram-positive bacteria kill C. elegans, although the precise mechanisms of killing remained open. We examined C. elegans as a pathogenesis model for the gram-positive bacterium Streptococcus pyogenes, a major human pathogen capable of causing a wide spectrum of diseases. We demonstrate that S. pyogenes kills C. elegans, both on solid and in liquid medium. Unlike P. aeruginosa and S. enterica serovar Typhimurium, the killing by S. pyogenes is solely mediated by hydrogen peroxide. Killing required live streptococci; the killing capacity depends on the amount of hydrogen peroxide produced, and killing can be inhibited by catalase. Major exotoxins of S. pyogenes are not involved in the killing process as confirmed by using specific toxin inhibitors and knockout mutants. Moreover, no accumulation of S. pyogenes in C. elegans is observed, which excludes the involvement of infection-like processes. Preliminary results show that S. pneumoniae can also kill C. elegans by hydrogen peroxide production. Hydrogen peroxide-mediated killing might represent a common mechanism by which gram-positive, catalase-negative pathogens kill C. elegans.

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