1
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Alkan C, Brésard G, Frézal L, Richaud A, Ruaud A, Zhang G, Félix MA. Natural variation in infection specificity of Caenorhabditis briggsae isolates by two RNA viruses. PLoS Pathog 2024; 20:e1012259. [PMID: 38861582 PMCID: PMC11195985 DOI: 10.1371/journal.ppat.1012259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/24/2024] [Accepted: 05/14/2024] [Indexed: 06/13/2024] Open
Abstract
Antagonistic relationships such as host-virus interactions potentially lead to rapid evolution and specificity in interactions. The Orsay virus is so far the only horizontal virus naturally infecting the nematode C. elegans. In contrast, several related RNA viruses infect its congener C. briggsae, including Santeuil (SANTV) and Le Blanc (LEBV) viruses. Here we focus on the host's intraspecific variation in sensitivity to these two intestinal viruses. Many temperate-origin C. briggsae strains, including JU1264 and JU1498, are sensitive to both, while many tropical strains, such as AF16, are resistant to both. Interestingly, some C. briggsae strains exhibit a specific resistance, such as the HK104 strain, specifically resistant to LEBV. The viral sensitivity pattern matches the strains' geographic and genomic relationships. The heavily infected strains mount a seemingly normal small RNA response that is insufficient to suppress viral infection, while the resistant strains show no small RNA response, suggesting an early block in viral entry or replication. We use a genetic approach from the host side to map genomic regions participating in viral resistance polymorphisms. Using Advanced Intercrossed Recombinant Inbred Lines (RILs) between virus-resistant AF16 and SANTV-sensitive HK104, we detect Quantitative Trait Loci (QTLs) on chromosomes IV and III. Building RILs between virus-sensitive JU1498 and LEBV-resistant HK104 followed by bulk segregant analysis, we identify a chromosome II QTL. In both cases, further introgressions of the regions confirmed the QTLs. This diversity provides an avenue for studying virus entry, replication, and exit mechanisms, as well as host-virus specificity and the host response to a specific virus infection.
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Affiliation(s)
- Cigdem Alkan
- IBENS, Department of Biology, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Gautier Brésard
- IBENS, Department of Biology, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Lise Frézal
- IBENS, Department of Biology, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
- Institut Pasteur, Université Paris Cité, Unité des Bactéries pathogènes entériques Paris, Paris, France
| | - Aurélien Richaud
- IBENS, Department of Biology, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Albane Ruaud
- IBENS, Department of Biology, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Gaotian Zhang
- IBENS, Department of Biology, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Marie-Anne Félix
- IBENS, Department of Biology, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
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2
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Bedet C, Quarato P, Palladino F, Cecere G, Robert VJ. The C. elegans SET1 histone methyltransferase SET-2 is not required for transgenerational memory of silencing. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001143. [PMID: 38808193 PMCID: PMC11130714 DOI: 10.17912/micropub.biology.001143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/22/2024] [Accepted: 05/09/2024] [Indexed: 05/30/2024]
Abstract
The SET-2 /SET1 histone H3K4 methyltransferase and RNAi pathway components are required to maintain fertility across generations in C. elegans . SET-2 preserves the germline transcriptional program transgenerationally, and RNAi pathways rely on small RNAs to establish and maintain transgenerational gene silencing. We investigated whether the functionality of RNAi-induced transgenerational silencing and the composition of pools of endogenous small RNA are affected by the absence of SET-2 . Our results suggest that defects in RNAi pathways are not responsible for the transcriptional misregulation observed in the absence of SET-2 .
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Affiliation(s)
- Cécile Bedet
- Ecole Normale Supérieure de Lyon, Laboratory of Biology and Modeling of the Cell, CNRS UMR5239, Inserm U1293, University Claude Bernard Lyon 1, 69007 Lyon, France Auvergne-Rhône-Alpes, France
| | - Piergiuseppe Quarato
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, CNRS UMR3738, Paris, France
- Current address: San Raffaele Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Francesca Palladino
- Ecole Normale Supérieure de Lyon, Laboratory of Biology and Modeling of the Cell, CNRS UMR5239, Inserm U1293, University Claude Bernard Lyon 1, 69007 Lyon, France Auvergne-Rhône-Alpes, France
| | - Germano Cecere
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, CNRS UMR3738, Paris, France
| | - Valérie J Robert
- Ecole Normale Supérieure de Lyon, Laboratory of Biology and Modeling of the Cell, CNRS UMR5239, Inserm U1293, University Claude Bernard Lyon 1, 69007 Lyon, France Auvergne-Rhône-Alpes, France
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3
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Chou HT, Valencia F, Alexander JC, Bell AD, Deb D, Pollard DA, Paaby AB. Diversification of small RNA pathways underlies germline RNA interference incompetence in wild Caenorhabditis elegans strains. Genetics 2024; 226:iyad191. [PMID: 37865119 PMCID: PMC10763538 DOI: 10.1093/genetics/iyad191] [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: 07/09/2023] [Revised: 07/09/2023] [Accepted: 08/12/2023] [Indexed: 10/23/2023] Open
Abstract
The discovery that experimental delivery of dsRNA can induce gene silencing at target genes revolutionized genetics research, by both uncovering essential biological processes and creating new tools for developmental geneticists. However, the efficacy of exogenous RNA interference (RNAi) varies dramatically within the Caenorhabditis elegans natural population, raising questions about our understanding of RNAi in the lab relative to its activity and significance in nature. Here, we investigate why some wild strains fail to mount a robust RNAi response to germline targets. We observe diversity in mechanism: in some strains, the response is stochastic, either on or off among individuals, while in others, the response is consistent but delayed. Increased activity of the Argonaute PPW-1, which is required for germline RNAi in the laboratory strain N2, rescues the response in some strains but dampens it further in others. Among wild strains, genes known to mediate RNAi exhibited very high expression variation relative to other genes in the genome as well as allelic divergence and strain-specific instances of pseudogenization at the sequence level. Our results demonstrate functional diversification in the small RNA pathways in C. elegans and suggest that RNAi processes are evolving rapidly and dynamically in nature.
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Affiliation(s)
- Han Ting Chou
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Francisco Valencia
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Jacqueline C Alexander
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Department of Microbiology, University of Washington, Seattle, WA 98109, USA
| | - Avery Davis Bell
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Diptodip Deb
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Janelia Research Campus, Ashburn, VA 20147, USA
| | - Daniel A Pollard
- Department of Biology, Western Washington University, Bellingham, WA 98225, USA
| | - Annalise B Paaby
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
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4
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Frézal L, Saglio M, Zhang G, Noble L, Richaud A, Félix MA. Genome-wide association and environmental suppression of the mortal germline phenotype of wild C. elegans. EMBO Rep 2023; 24:e58116. [PMID: 37983674 DOI: 10.15252/embr.202358116] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/19/2023] [Accepted: 10/27/2023] [Indexed: 11/22/2023] Open
Abstract
The animal germline lineage needs to be maintained along generations. However, some Caenorhabditis elegans wild isolates display a mortal germline phenotype, leading to sterility after several generations at 25°C. Using a genome-wide association approach, we detect a significant peak on chromosome III around 5 Mb, confirmed by introgressions. Thus, a seemingly deleterious genotype is maintained at intermediate frequency in the species. Environmental rescue is a likely explanation, and indeed associated bacteria and microsporidia suppress the phenotype of wild isolates as well as mutants in small RNA inheritance (nrde-2) and histone modifications (set-2). Escherichia coli strains of the K-12 lineage suppress the phenotype compared to B strains. By shifting a wild strain from E. coli K-12 to E. coli B, we find that memory of the suppressing condition is maintained over several generations. Thus, the mortal germline phenotype of wild C. elegans is in part revealed by laboratory conditions and may represent variation in epigenetic inheritance and environmental interactions. This study also points to the importance of non-genetic memory in the face of environmental variation.
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Affiliation(s)
- Lise Frézal
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France
| | - Marie Saglio
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France
| | - Gaotian Zhang
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France
| | - Luke Noble
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France
| | - Aurélien Richaud
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France
| | - Marie-Anne Félix
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France
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5
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Ewe CK, Rechavi O. Natural probiotics improve heritable sterility. EMBO Rep 2023; 24:e58318. [PMID: 37983676 DOI: 10.15252/embr.202358318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 10/18/2023] [Indexed: 11/22/2023] Open
Abstract
Disrupting the small RNA pathway and chromatin-modifying enzymes in C. elegans often leads to a mortal germline (Mrt) phenotype, characterized by progressive sterility observed over multiple generations at elevated temperature. This phenotype arises from the inheritance of aberrant epigenetic memory across generations. In this issue of EMBO Reports, Frézal and colleagues reported that, while in standard laboratory environment C. elegans wild isolates exhibit the Mrt phenotype, sterility does not occur when the worms are exposed to naturally associated bacteria and microsporidia. Excitingly, diet-induced epigenetic memory may persist for multiple generations. This suggests intriguing diet-gene interactions in modulating nongenetic inheritance, potentially shaping the evolutionary trajectory of the animals.
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Affiliation(s)
- Chee Kiang Ewe
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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6
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Earley TS, Feiner N, Alvarez MF, Coolon JD, Sultan SE. The relative impact of parental and current environment on plant transcriptomes depends on type of stress and genotype. Proc Biol Sci 2023; 290:20230824. [PMID: 37752834 PMCID: PMC10523085 DOI: 10.1098/rspb.2023.0824] [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: 04/06/2023] [Accepted: 08/30/2023] [Indexed: 09/28/2023] Open
Abstract
Through developmental plasticity, an individual organism integrates influences from its immediate environment with those due to the environment of its parents. While both effects on phenotypes are well documented, their relative impact has been little studied in natural systems, especially at the level of gene expression. We examined this issue in four genotypes of the annual plant Persicaria maculosa by varying two key resources-light and soil moisture-in both generations. Transcriptomic analyses showed that the relative effects of parent and offspring environment on gene expression (i.e. the number of differentially expressed transcripts, DETs) varied both for the two types of resource stress and among genotypes. For light, immediate environment induced more DETs than parental environment for all genotypes, although the precise proportion of parental versus immediate DETs varied among genotypes. By contrast, the relative effect of soil moisture varied dramatically among genotypes, from 8-fold more DETs due to parental than immediate conditions to 10-fold fewer. These findings provide evidence at the transcriptomic level that the relative impacts of parental and immediate environment on the developing organism may depend on the environmental factor and vary strongly among genotypes, providing potential for the interplay of these developmental influences to evolve.
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Affiliation(s)
- Timothy S. Earley
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | | | - Mariano F. Alvarez
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Joseph D. Coolon
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Sonia E. Sultan
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
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7
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Bell AD, Chou HT, Valencia F, Paaby AB. Beyond the reference: gene expression variation and transcriptional response to RNA interference in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2023; 13:jkad112. [PMID: 37221008 PMCID: PMC10411595 DOI: 10.1093/g3journal/jkad112] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/11/2023] [Accepted: 05/15/2023] [Indexed: 05/25/2023]
Abstract
Though natural systems harbor genetic and phenotypic variation, research in model organisms is often restricted to a reference strain. Focusing on a reference strain yields a great depth of knowledge but potentially at the cost of breadth of understanding. Furthermore, tools developed in the reference context may introduce bias when applied to other strains, posing challenges to defining the scope of variation within model systems. Here, we evaluate how genetic differences among 5 wild Caenorhabditis elegans strains affect gene expression and its quantification, in general and after induction of the RNA interference (RNAi) response. Across strains, 34% of genes were differentially expressed in the control condition, including 411 genes that were not expressed at all in at least 1 strain; 49 of these were unexpressed in reference strain N2. Reference genome mapping bias caused limited concern: despite hyperdiverse hotspots throughout the genome, 92% of variably expressed genes were robust to mapping issues. The transcriptional response to RNAi was highly strain- and target-gene-specific and did not correlate with RNAi efficiency, as the 2 RNAi-insensitive strains showed more differentially expressed genes following RNAi treatment than the RNAi-sensitive reference strain. We conclude that gene expression, generally and in response to RNAi, differs across C. elegans strains such that the choice of strain may meaningfully influence scientific inferences. Finally, we introduce a resource for querying gene expression variation in this dataset at https://wildworm.biosci.gatech.edu/rnai/.
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Affiliation(s)
- Avery Davis Bell
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Dr NW, EBB Building, Atlanta, GA 30332, USA
| | - Han Ting Chou
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Dr NW, EBB Building, Atlanta, GA 30332, USA
| | - Francisco Valencia
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Dr NW, EBB Building, Atlanta, GA 30332, USA
| | - Annalise B Paaby
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Dr NW, EBB Building, Atlanta, GA 30332, USA
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8
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Li Z, Fouad AD, Bowlin PD, Fan Y, He S, Chang MC, Du A, Teng C, Kassouni A, Ji H, Raizen DM, Fang-Yen C. A robotic system for automated genetic manipulation and analysis of Caenorhabditis elegans. PNAS NEXUS 2023; 2:pgad197. [PMID: 37416871 PMCID: PMC10321491 DOI: 10.1093/pnasnexus/pgad197] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/04/2023] [Accepted: 06/06/2023] [Indexed: 07/08/2023]
Abstract
The nematode Caenorhabditis elegans is one of the most widely studied organisms in biology due to its small size, rapid life cycle, and manipulable genetics. Research with C. elegans depends on labor-intensive and time-consuming manual procedures, imposing a major bottleneck for many studies, especially for those involving large numbers of animals. Here, we describe a general-purpose tool, WormPicker, a robotic system capable of performing complex genetic manipulations and other tasks by imaging, phenotyping, and transferring C. elegans on standard agar media. Our system uses a motorized stage to move an imaging system and a robotic arm over an array of agar plates. Machine vision tools identify animals and assay developmental stage, morphology, sex, expression of fluorescent reporters, and other phenotypes. Based on the results of these assays, the robotic arm selectively transfers individual animals using an electrically self-sterilized wire loop, with the aid of machine vision and electrical capacitance sensing. Automated C. elegans manipulation shows reliability and throughput comparable with standard manual methods. We developed software to enable the system to autonomously carry out complex protocols. To validate the effectiveness and versatility of our methods, we used the system to perform a collection of common C. elegans procedures, including genetic crossing, genetic mapping, and genomic integration of a transgene. Our robotic system will accelerate C. elegans research and open possibilities for performing genetic and pharmacological screens that would be impractical using manual methods.
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Affiliation(s)
- Zihao Li
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anthony D Fouad
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Peter D Bowlin
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yuying Fan
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Siming He
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Meng-Chuan Chang
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Angelica Du
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christopher Teng
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alexander Kassouni
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hongfei Ji
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - David M Raizen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christopher Fang-Yen
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH 43210, USA
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9
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Dubois C, Félix MA. A QTL on chromosome IV explains a natural variation of QR.pap final position in Caenorhabditis elegans. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000836. [PMID: 37273577 PMCID: PMC10238922 DOI: 10.17912/micropub.biology.000836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/04/2023] [Accepted: 05/12/2023] [Indexed: 06/06/2023]
Abstract
In Caenorhabditis elegans , the QR neuroblast and its progeny migrate from the posterior to the anterior part of the animal during the L1 stage. We previously showed that the final position of QR.pa daughters varies among C. elegans wild isolates, with CB4932 displaying a particularly anterior QR.pap position (Dubois et al., 2021). Here, we study the genetic basis of the variation between isolates CB4932 and JU1242. We show that JU1242 alleles behave in a mostly dominant fashion. Using a Bulk Segregant Analysis, we detect a quantitative trait locus (QTL) region on chromosome IV. This QTL was confirmed using reciprocal chromosome IV introgressions.
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Affiliation(s)
- Clément Dubois
- Institut de Biologie de l'École Normale Supérieure, Paris, Île-de-France, France
| | - Marie-Anne Félix
- Institut de Biologie de l'École Normale Supérieure, Paris, Île-de-France, France
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10
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Bell AD, Chou HT, Paaby AB. Beyond the reference: gene expression variation and transcriptional response to RNAi in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.24.533964. [PMID: 36993640 PMCID: PMC10055391 DOI: 10.1101/2023.03.24.533964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A universal feature of living systems is that natural variation in genotype underpins variation in phenotype. Yet, research in model organisms is often constrained to a single genetic background, the reference strain. Further, genomic studies that do evaluate wild strains typically rely on the reference strain genome for read alignment, leading to the possibility of biased inferences based on incomplete or inaccurate mapping; the extent of reference bias can be difficult to quantify. As an intermediary between genome and organismal traits, gene expression is well positioned to describe natural variability across genotypes generally and in the context of environmental responses, which can represent complex adaptive phenotypes. C. elegans sits at the forefront of investigation into small-RNA gene regulatory mechanisms, or RNA interference (RNAi), and wild strains exhibit natural variation in RNAi competency following environmental triggers. Here, we examine how genetic differences among five wild strains affect the C. elegans transcriptome in general and after inducing RNAi responses to two germline target genes. Approximately 34% of genes were differentially expressed across strains; 411 genes were not expressed at all in at least one strain despite robust expression in others, including 49 genes not expressed in reference strain N2. Despite the presence of hyper-diverse hotspots throughout the C. elegans genome, reference mapping bias was of limited concern: over 92% of variably expressed genes were robust to mapping issues. Overall, the transcriptional response to RNAi was strongly strain-specific and highly specific to the target gene, and the laboratory strain N2 was not representative of the other strains. Moreover, the transcriptional response to RNAi was not correlated with RNAi phenotypic penetrance; the two germline RNAi incompetent strains exhibited substantial differential gene expression following RNAi treatment, indicating an RNAi response despite failure to reduce expression of the target gene. We conclude that gene expression, both generally and in response to RNAi, differs across C. elegans strains such that choice of strain may meaningfully influence scientific conclusions. To provide a public, easily accessible resource for querying gene expression variation in this dataset, we introduce an interactive website at https://wildworm.biosci.gatech.edu/rnai/ .
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Affiliation(s)
- Avery Davis Bell
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA
| | - Han Ting Chou
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA
| | - Annalise B. Paaby
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA
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11
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Wang W, Flury AG, Rodriguez AT, Garrison JL, Brem RB. A role for worm cutl-24 in background- and parent-of-origin-dependent ER stress resistance. BMC Genomics 2022; 23:842. [PMID: 36539699 PMCID: PMC9764823 DOI: 10.1186/s12864-022-09063-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 12/03/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Organisms in the wild can acquire disease- and stress-resistance traits that outstrip the programs endogenous to humans. Finding the molecular basis of such natural resistance characters is a key goal of evolutionary genetics. Standard statistical-genetic methods toward this end can perform poorly in organismal systems that lack high rates of meiotic recombination, like Caenorhabditis worms. RESULTS Here we discovered unique ER stress resistance in a wild Kenyan C. elegans isolate, which in inter-strain crosses was passed by hermaphrodite mothers to hybrid offspring. We developed an unbiased version of the reciprocal hemizygosity test, RH-seq, to explore the genetics of this parent-of-origin-dependent phenotype. Among top-scoring gene candidates from a partial-coverage RH-seq screen, we focused on the neuronally-expressed, cuticlin-like gene cutl-24 for validation. In gene-disruption and controlled crossing experiments, we found that cutl-24 was required in Kenyan hermaphrodite mothers for ER stress tolerance in their inter-strain hybrid offspring; cutl-24 was also a contributor to the trait in purebred backgrounds. CONCLUSIONS These data establish the Kenyan strain allele of cutl-24 as a determinant of a natural stress-resistant state, and they set a precedent for the dissection of natural trait diversity in invertebrate animals without the need for a panel of meiotic recombinants.
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Affiliation(s)
- Wenke Wang
- Buck Institute for Research on Aging, Novato, CA, United States
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, United States
| | - Anna G Flury
- Buck Institute for Research on Aging, Novato, CA, United States
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, United States
| | - Andrew T Rodriguez
- Buck Institute for Research on Aging, Novato, CA, United States
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, United States
| | - Jennifer L Garrison
- Buck Institute for Research on Aging, Novato, CA, United States.
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, United States.
- Department of Cellular and Molecular Pharmacology, UC San Francisco, San Francisco, CA, United States.
- Global Consortium for Reproductive Longevity & Equality, Novato, CA, United States.
| | - Rachel B Brem
- Buck Institute for Research on Aging, Novato, CA, United States.
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, United States.
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, United States.
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12
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Saber S, Snyder M, Rajaei M, Baer CF. Mutation, selection, and the prevalence of the Caenorhabditis elegans heat-sensitive mortal germline phenotype. G3 (BETHESDA, MD.) 2022; 12:jkac063. [PMID: 35311992 PMCID: PMC9073675 DOI: 10.1093/g3journal/jkac063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/10/2022] [Indexed: 11/17/2022]
Abstract
Caenorhabditis elegans strains with the heat-sensitive mortal germline phenotype become progressively sterile over the course of a few tens of generations when maintained at temperatures near the upper range of C. elegans' tolerance. Mortal germline is transgenerationally heritable, and proximately under epigenetic control. Previous studies have suggested that mortal germline presents a relatively large mutational target and that mortal germline is not uncommon in natural populations of C. elegans. The mortal germline phenotype is not monolithic. Some strains exhibit a strong mortal germline phenotype, in which individuals invariably become sterile over a few generations, whereas other strains show a weaker (less penetrant) phenotype in which the onset of sterility is slower and more stochastic. We present results in which we (1) quantify the rate of mutation to the mortal germline phenotype and (2) quantify the frequency of mortal germline in a collection of 95 wild isolates. Over the course of ∼16,000 meioses, we detected one mutation to a strong mortal germline phenotype, resulting in a point estimate of the mutation rate UMrt≈ 6×10-5/genome/generation. We detected no mutations to a weak mortal germline phenotype. Six out of 95 wild isolates have a strong mortal germline phenotype, and although quantification of the weak mortal germline phenotype is inexact, the weak mortal germline phenotype is not rare in nature. We estimate a strength of selection against mutations conferring the strong mortal germline phenotype s¯≈0.1%, similar to selection against mutations affecting competitive fitness. The appreciable frequency of weak mortal germline variants in nature combined with the low mutation rate suggests that mortal germline may be maintained by balancing selection.
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Affiliation(s)
- Sayran Saber
- Department of Biology, University of Florida, Gainesville, FL 32611-8525, USA
| | - Michael Snyder
- Department of Biology, University of Florida, Gainesville, FL 32611-8525, USA
| | - Moein Rajaei
- Department of Biology, University of Florida, Gainesville, FL 32611-8525, USA
| | - Charles F Baer
- Department of Biology, University of Florida, Gainesville, FL 32611-8525, USA
- University of Florida Genetics Institute, Gainesville, FL 32610, USA
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13
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Toker IA, Lev I, Mor Y, Gurevich Y, Fisher D, Houri-Zeevi L, Antonova O, Doron H, Anava S, Gingold H, Hadany L, Shaham S, Rechavi O. Transgenerational inheritance of sexual attractiveness via small RNAs enhances evolvability in C. elegans. Dev Cell 2022; 57:298-309.e9. [PMID: 35134343 PMCID: PMC8826646 DOI: 10.1016/j.devcel.2022.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 09/12/2021] [Accepted: 01/05/2022] [Indexed: 11/16/2022]
Abstract
It is unknown whether transient transgenerational epigenetic responses to environmental challenges affect the process of evolution, which typically unfolds over many generations. Here, we show that in C. elegans, inherited small RNAs control genetic variation by regulating the crucial decision of whether to self-fertilize or outcross. We found that under stressful temperatures, younger hermaphrodites secrete a male-attracting pheromone. Attractiveness transmits transgenerationally to unstressed progeny via heritable small RNAs and the Argonaute Heritable RNAi Deficient-1 (HRDE-1). We identified an endogenous small interfering RNA pathway, enriched in endo-siRNAs that target sperm genes, that transgenerationally regulates sexual attraction, male prevalence, and outcrossing rates. Multigenerational mating competition experiments and mathematical simulations revealed that over generations, animals that inherit attractiveness mate more and their alleles spread in the population. We propose that the sperm serves as a "stress-sensor" that, via small RNA inheritance, promotes outcrossing in challenging environments when increasing genetic variation is advantageous.
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Affiliation(s)
- Itai Antoine Toker
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | - Itamar Lev
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | - Yael Mor
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | - Yael Gurevich
- School of Plant Sciences and Food Security, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Doron Fisher
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Leah Houri-Zeevi
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Olga Antonova
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Hila Doron
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Sarit Anava
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Hila Gingold
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Lilach Hadany
- School of Plant Sciences and Food Security, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA
| | - Oded Rechavi
- Department of Neurobiology, Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
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14
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Andersen EC, Rockman MV. Natural genetic variation as a tool for discovery in Caenorhabditis nematodes. Genetics 2022; 220:iyab156. [PMID: 35134197 PMCID: PMC8733454 DOI: 10.1093/genetics/iyab156] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 09/11/2021] [Indexed: 11/12/2022] Open
Abstract
Over the last 20 years, studies of Caenorhabditis elegans natural diversity have demonstrated the power of quantitative genetic approaches to reveal the evolutionary, ecological, and genetic factors that shape traits. These studies complement the use of the laboratory-adapted strain N2 and enable additional discoveries not possible using only one genetic background. In this chapter, we describe how to perform quantitative genetic studies in Caenorhabditis, with an emphasis on C. elegans. These approaches use correlations between genotype and phenotype across populations of genetically diverse individuals to discover the genetic causes of phenotypic variation. We present methods that use linkage, near-isogenic lines, association, and bulk-segregant mapping, and we describe the advantages and disadvantages of each approach. The power of C. elegans quantitative genetic mapping is best shown in the ability to connect phenotypic differences to specific genes and variants. We will present methods to narrow genomic regions to candidate genes and then tests to identify the gene or variant involved in a quantitative trait. The same features that make C. elegans a preeminent experimental model animal contribute to its exceptional value as a tool to understand natural phenotypic variation.
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Affiliation(s)
- Erik C Andersen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60201, USA
| | - Matthew V Rockman
- Department of Biology and Center for Genomics & Systems Biology, New York University, New York, NY 10003, USA
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15
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Abstract
Wild populations of the model organism C. elegans represent a valuable resource, allowing for genetic characterization underlying natural phenotypic variation. Here we provide a simple protocol on how to sample and rapidly identify C. elegans wild isolates. We outline how to find suitable habitats and organic substrates, followed by describing isolation and identification of C. elegans live cultures based on easily recognizable morphological characteristics, molecular barcodes, and mating tests. This protocol uses standard laboratory equipment and requires little prior knowledge of C. elegans biology.
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Affiliation(s)
| | - Nausicaa Poullet
- Université Côte d'Azur, CNRS, Inserm, IBV, Nice, France
- URZ, INRAE, Petit-Bourg (Guadeloupe), France
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16
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Özdemir I, Steiner FA. Transmission of chromatin states across generations in C. elegans. Semin Cell Dev Biol 2021; 127:133-141. [PMID: 34823984 DOI: 10.1016/j.semcdb.2021.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 11/18/2022]
Abstract
Epigenetic inheritance refers to the transmission of phenotypes across generations without affecting the genomic DNA sequence. Even though it has been documented in many species in fungi, animals and plants, the mechanisms underlying epigenetic inheritance are not fully uncovered. Epialleles, the heritable units of epigenetic information, can take the form of several biomolecules, including histones and their post-translational modifications (PTMs). Here, we review the recent advances in the understanding of the transmission of histone variants and histone PTM patterns across generations in C. elegans. We provide a general overview of the intergenerational and transgenerational inheritance of histone PTMs and their modifiers and discuss the interplay among different histone PTMs. We also evaluate soma-germ line communication and its impact on the inheritance of epigenetic traits.
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Affiliation(s)
- Isa Özdemir
- Department of Molecular Biology and Institute of Genetics and Genomics in Geneva, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva, Switzerland
| | - Florian A Steiner
- Department of Molecular Biology and Institute of Genetics and Genomics in Geneva, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva, Switzerland.
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17
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Cecere G. Small RNAs in epigenetic inheritance: from mechanisms to trait transmission. FEBS Lett 2021; 595:2953-2977. [PMID: 34671979 PMCID: PMC9298081 DOI: 10.1002/1873-3468.14210] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/08/2021] [Accepted: 10/18/2021] [Indexed: 01/02/2023]
Abstract
Inherited information is transmitted to progeny primarily by the genome through the gametes. However, in recent years, epigenetic inheritance has been demonstrated in several organisms, including animals. Although it is clear that certain post‐translational histone modifications, DNA methylation, and noncoding RNAs regulate epigenetic inheritance, the molecular mechanisms responsible for epigenetic inheritance are incompletely understood. This review focuses on the role of small RNAs in transmitting epigenetic information across generations in animals. Examples of documented cases of transgenerational epigenetic inheritance are discussed, from the silencing of transgenes to the inheritance of complex traits, such as fertility, stress responses, infections, and behavior. Experimental evidence supporting the idea that small RNAs are epigenetic molecules capable of transmitting traits across generations is highlighted, focusing on the mechanisms by which small RNAs achieve such a function. Just as the role of small RNAs in epigenetic processes is redefining the concept of inheritance, so too our understanding of the molecular pathways and mechanisms that govern epigenetic inheritance in animals is radically changing.
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Affiliation(s)
- Germano Cecere
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France
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18
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Evans KS, van Wijk MH, McGrath PT, Andersen EC, Sterken MG. From QTL to gene: C. elegans facilitates discoveries of the genetic mechanisms underlying natural variation. Trends Genet 2021; 37:933-947. [PMID: 34229867 DOI: 10.1016/j.tig.2021.06.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/01/2021] [Accepted: 06/03/2021] [Indexed: 11/15/2022]
Abstract
Although many studies have examined quantitative trait variation across many species, only a small number of genes and thereby molecular mechanisms have been discovered. Without these data, we can only speculate about evolutionary processes that underlie trait variation. Here, we review how quantitative and molecular genetics in the nematode Caenorhabditis elegans led to the discovery and validation of 37 quantitative trait genes over the past 15 years. Using these data, we can start to make inferences about evolution from these quantitative trait genes, including the roles that coding versus noncoding variation, gene family expansion, common versus rare variants, pleiotropy, and epistasis play in trait variation across this species.
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Affiliation(s)
- Kathryn S Evans
- Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL 60208, USA
| | - Marijke H van Wijk
- Laboratory of Nematology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Patrick T McGrath
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Erik C Andersen
- Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Mark G Sterken
- Laboratory of Nematology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands.
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19
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Koneru SL, Hintze M, Katsanos D, Barkoulas M. Cryptic genetic variation in a heat shock protein modifies the outcome of a mutation affecting epidermal stem cell development in C. elegans. Nat Commun 2021; 12:3263. [PMID: 34059684 PMCID: PMC8166903 DOI: 10.1038/s41467-021-23567-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 04/29/2021] [Indexed: 12/13/2022] Open
Abstract
A fundamental question in medical genetics is how the genetic background modifies the phenotypic outcome of mutations. We address this question by focusing on the seam cells, which display stem cell properties in the epidermis of Caenorhabditis elegans. We demonstrate that a putative null mutation in the GATA transcription factor egl-18, which is involved in seam cell fate maintenance, is more tolerated in the CB4856 isolate from Hawaii than the lab reference strain N2 from Bristol. We identify multiple quantitative trait loci (QTLs) underlying the difference in phenotype expressivity between the two isolates. These QTLs reveal cryptic genetic variation that reinforces seam cell fate through potentiating Wnt signalling. Within one QTL region, a single amino acid deletion in the heat shock protein HSP-110 in CB4856 is sufficient to modify Wnt signalling and seam cell development, highlighting that natural variation in conserved heat shock proteins can shape phenotype expressivity. How the genetic background modifies the expression of mutations is a key question that is addressed in this study in the context of seam cell development in Caenorhabditis elegans isolates. One amino acid deletion in a conserved heat shock protein is sufficient to shape phenotype expressivity upon mutation of a GATA transcription factor.
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Affiliation(s)
- Sneha L Koneru
- Department of Life Sciences, Imperial College, London, United Kingdom
| | - Mark Hintze
- Department of Life Sciences, Imperial College, London, United Kingdom
| | - Dimitris Katsanos
- Department of Life Sciences, Imperial College, London, United Kingdom
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20
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Willis AR, Sukhdeo R, Reinke AW. Remembering your enemies: mechanisms of within-generation and multigenerational immune priming in Caenorhabditis elegans. FEBS J 2020; 288:1759-1770. [PMID: 32767821 DOI: 10.1111/febs.15509] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/17/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022]
Abstract
Pathogens are abundant and drive evolution of host immunity. Whilst immune memory is classically associated with adaptive immunity, studies in diverse species now show that priming of innate immune defences can also protect against secondary infection. Remarkably, priming may also be passed on to progeny to enhance pathogen resistance and promote survival in future generations. Phenotypic changes that occur independent of DNA sequence underlie both 'within-generation' priming and 'multigenerational' priming. However, the molecular mechanisms responsible for these phenomena are still poorly understood. Caenorhabditis elegans is a simple and genetically tractable model organism that has enabled key advances in immunity and environmental epigenetics. Using both natural and human pathogens, researchers have uncovered numerous examples of innate immune priming in this animal. Viral infection models have provided key evidence for a conserved antiviral RNA silencing mechanism that is inherited in progeny. Bacterial infection models have explored mechanisms of within-generation and multigenerational priming that span chromatin modification and transcriptional changes, small RNA pathways, maternal provisioning and pathogen avoidance strategies. Together, these studies are providing novel insight into the immune reactivity of the genome and have important consequences for our understanding of health and evolution. In this review, we present the current evidence for learned protection against pathogens in C. elegans, discuss the significance and limitations of these findings and highlight important avenues of future investigation.
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Affiliation(s)
| | - Ronesh Sukhdeo
- Department of Molecular Genetics, University of Toronto, ON, Canada
| | - Aaron W Reinke
- Department of Molecular Genetics, University of Toronto, ON, Canada
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21
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Baugh LR, Day T. Nongenetic inheritance and multigenerational plasticity in the nematode C. elegans. eLife 2020; 9:e58498. [PMID: 32840479 PMCID: PMC7447421 DOI: 10.7554/elife.58498] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/13/2020] [Indexed: 02/07/2023] Open
Abstract
A rapidly growing body of literature in several organisms suggests that environmentally-induced adaptive changes in phenotype can be transmitted across multiple generations. Although within-generation plasticity has been well documented, multigenerational plasticity represents a significant departure from conventional evolutionary thought. Studies of C. elegans have been particularly influential because this species exhibits extensive phenotypic plasticity, it is often essentially isogenic, and it has well-documented molecular and cellular mechanisms through which nongenetic inheritance occurs. However, while experimentalists are eager to claim that nongenetic modes of inheritance characterized in this and other model systems enhance fitness, many biologists remain skeptical given the extraordinary nature of this claim. We establish three criteria to evaluate how compelling the evidence for adaptive multigenerational plasticity is, and we use these criteria to critically examine putative cases of it in C. elegans. We conclude by suggesting potentially fruitful avenues for future research.
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Affiliation(s)
- L Ryan Baugh
- Department of Biology, Center for Genomics and Computational Biology, Duke UniversityDurhamUnited States
| | - Troy Day
- Departments of Mathematics and Statistics, Department of Biology, Queens UniversityKingstonCanada
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22
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Godinho DP, Cruz MA, Charlery de la Masselière M, Teodoro‐Paulo J, Eira C, Fragata I, Rodrigues LR, Zélé F, Magalhães S. Creating outbred and inbred populations in haplodiploids to measure adaptive responses in the laboratory. Ecol Evol 2020; 10:7291-7305. [PMID: 32760529 PMCID: PMC7391545 DOI: 10.1002/ece3.6454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 05/05/2020] [Indexed: 12/15/2022] Open
Abstract
Laboratory studies are often criticized for not being representative of processes occurring in natural populations. One reason for this is the fact that laboratory populations generally do not capture enough of the genetic variation of natural populations. This can be mitigated by mixing the genetic background of several field populations when creating laboratory populations. From these outbred populations, it is possible to generate inbred lines, thereby freezing and partitioning part of their variability, allowing each genotype to be characterized independently. Many studies addressing adaptation of organisms to their environment, such as those involving quantitative genetics or experimental evolution, rely on inbred or outbred populations, but the methodology underlying the generation of such biological resources is usually not explicitly documented. Here, we developed different procedures to circumvent common pitfalls of laboratory studies, and illustrate their application using two haplodiploid species, the spider mites Tetranychus urticae and Tetranychus evansi. First, we present a method that increases the chance of capturing high amounts of variability when creating outbred populations, by performing controlled crosses between individuals from different field-collected populations. Second, we depict the creation of inbred lines derived from such outbred populations, by performing several generations of sib-mating. Third, we outline an experimental evolution protocol that allows the maintenance of a constant population size at the beginning of each generation, thereby preventing bottlenecks and diminishing extinction risks. Finally, we discuss the advantages of these procedures and emphasize that sharing such biological resources and combining them with available genetic tools will allow consistent and comparable studies that greatly contribute to our understanding of ecological and evolutionary processes.
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Affiliation(s)
- Diogo P. Godinho
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Miguel A. Cruz
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Maud Charlery de la Masselière
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Jéssica Teodoro‐Paulo
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Cátia Eira
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Inês Fragata
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Leonor R. Rodrigues
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Flore Zélé
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
| | - Sara Magalhães
- Centre for Ecology, Evolution and Environmental Changes – cE3cFaculdade de Ciências da Universidade de LisboaLisboaPortugal
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23
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Natural cryptic variation in epigenetic modulation of an embryonic gene regulatory network. Proc Natl Acad Sci U S A 2020; 117:13637-13646. [PMID: 32482879 DOI: 10.1073/pnas.1920343117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Gene regulatory networks (GRNs) that direct animal embryogenesis must respond to varying environmental and physiological conditions to ensure robust construction of organ systems. While GRNs are evolutionarily modified by natural genomic variation, the roles of epigenetic processes in shaping plasticity of GRN architecture are not well understood. The endoderm GRN in Caenorhabditis elegans is initiated by the maternally supplied SKN-1/Nrf2 bZIP transcription factor; however, the requirement for SKN-1 in endoderm specification varies widely among distinct C. elegans wild isotypes, owing to rapid developmental system drift driven by accumulation of cryptic genetic variants. We report here that heritable epigenetic factors that are stimulated by transient developmental diapause also underlie cryptic variation in the requirement for SKN-1 in endoderm development. This epigenetic memory is inherited from the maternal germline, apparently through a nuclear, rather than cytoplasmic, signal, resulting in a parent-of-origin effect (POE), in which the phenotype of the progeny resembles that of the maternal founder. The occurrence and persistence of POE varies between different parental pairs, perduring for at least 10 generations in one pair. This long-perduring POE requires piwi-interacting RNA (piRNA) function and the germline nuclear RNA interference (RNAi) pathway, as well as MET-2 and SET-32, which direct histone H3K9 trimethylation and drive heritable epigenetic modification. Such nongenetic cryptic variation may provide a resource of additional phenotypic diversity through which adaptation may facilitate evolutionary changes and shape developmental regulatory systems.
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24
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Ewe CK, Torres Cleuren YN, Rothman JH. Evolution and Developmental System Drift in the Endoderm Gene Regulatory Network of Caenorhabditis and Other Nematodes. Front Cell Dev Biol 2020; 8:170. [PMID: 32258041 PMCID: PMC7093329 DOI: 10.3389/fcell.2020.00170] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/02/2020] [Indexed: 01/17/2023] Open
Abstract
Developmental gene regulatory networks (GRNs) underpin metazoan embryogenesis and have undergone substantial modification to generate the tremendous variety of animal forms present on Earth today. The nematode Caenorhabditis elegans has been a central model for advancing many important discoveries in fundamental mechanistic biology and, more recently, has provided a strong base from which to explore the evolutionary diversification of GRN architecture and developmental processes in other species. In this short review, we will focus on evolutionary diversification of the GRN for the most ancient of the embryonic germ layers, the endoderm. Early embryogenesis diverges considerably across the phylum Nematoda. Notably, while some species deploy regulative development, more derived species, such as C. elegans, exhibit largely mosaic modes of embryogenesis. Despite the relatively similar morphology of the nematode gut across species, widespread variation has been observed in the signaling inputs that initiate the endoderm GRN, an exemplar of developmental system drift (DSD). We will explore how genetic variation in the endoderm GRN helps to drive DSD at both inter- and intraspecies levels, thereby resulting in a robust developmental system. Comparative studies using divergent nematodes promise to unveil the genetic mechanisms controlling developmental plasticity and provide a paradigm for the principles governing evolutionary modification of an embryonic GRN.
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Affiliation(s)
- Chee Kiang Ewe
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
| | | | - Joel H. Rothman
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
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25
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Irvine SQ. Embryonic canalization and its limits-A view from temperature. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2020; 334:128-144. [PMID: 32011096 DOI: 10.1002/jez.b.22930] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 01/17/2020] [Accepted: 01/21/2020] [Indexed: 02/06/2023]
Abstract
Many animals are able to produce similar offspring over a range of environmental conditions. This property of the developmental process has been termed canalization-the channeling of developmental pathways to generate a stable outcome despite varying conditions. Temperature is one environmental parameter that has fundamental effects on cell physiology and biochemistry, yet developmental programs generally result in a stable phenotype under a range of temperatures. On the other hand, there are typically upper and lower temperature limits beyond which the developmental program is unable to produce normal offspring. This review summarizes data on how development is affected by temperature, particularly high temperature, in various animal species. It also brings together information on potential cell biological and developmental genetic factors that may be responsible for developmental stability in varying temperatures, and likely critical mechanisms that break down at high temperature. Also reviewed are possible means for studying temperature effects on embryogenesis and how to determine which factors are most critical at the high-temperature limits for normal development. Increased knowledge of these critical factors will point to the targets of selection under climate change, and more generally, how developmental robustness in varying environments is maintained.
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Affiliation(s)
- Steven Q Irvine
- Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island
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26
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Barucci G, Cornes E, Singh M, Li B, Ugolini M, Samolygo A, Didier C, Dingli F, Loew D, Quarato P, Cecere G. Small-RNA-mediated transgenerational silencing of histone genes impairs fertility in piRNA mutants. Nat Cell Biol 2020; 22:235-245. [PMID: 32015436 PMCID: PMC7272227 DOI: 10.1038/s41556-020-0462-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 01/05/2020] [Indexed: 11/09/2022]
Abstract
PIWI-interacting RNAs (piRNAs) promote fertility in many animals. However, whether this is due to their conserved role in repressing repetitive elements (REs) remains unclear. Here, we show that the progressive loss of fertility in Caenorhabditis elegans lacking piRNAs is not caused by derepression of REs or other piRNA targets but, rather, is mediated by epigenetic silencing of all of the replicative histone genes. In the absence of piRNAs, downstream components of the piRNA pathway relocalize from germ granules and piRNA targets to histone mRNAs to synthesize antisense small RNAs (sRNAs) and induce transgenerational silencing. Removal of the downstream components of the piRNA pathway restores histone mRNA expression and fertility in piRNA mutants, and the inheritance of histone sRNAs in wild-type worms adversely affects their fertility for multiple generations. We conclude that sRNA-mediated silencing of histone genes impairs the fertility of piRNA mutants and may serve to maintain piRNAs across evolution.
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Affiliation(s)
- Giorgia Barucci
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Sorbonne Université, Collège doctoral, Paris, France
| | - Eric Cornes
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
| | - Meetali Singh
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
| | - Blaise Li
- Bioinformatics and Biostatistics Hub, C3BI, Institut Pasteur, USR 3756, CNRS, Paris, France
| | - Martino Ugolini
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Scuola Normale Superiore, Pisa, Italy
| | - Aleksei Samolygo
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Moscow Institute of Physics and Technology, Moscow, Russia
| | - Celine Didier
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
| | - Florent Dingli
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Damarys Loew
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Piergiuseppe Quarato
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Sorbonne Université, Collège doctoral, Paris, France
| | - Germano Cecere
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France.
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27
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Beets I, Zhang G, Fenk LA, Chen C, Nelson GM, Félix MA, de Bono M. Natural Variation in a Dendritic Scaffold Protein Remodels Experience-Dependent Plasticity by Altering Neuropeptide Expression. Neuron 2019; 105:106-121.e10. [PMID: 31757604 PMCID: PMC6953435 DOI: 10.1016/j.neuron.2019.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 08/18/2019] [Accepted: 09/28/2019] [Indexed: 12/13/2022]
Abstract
The extent to which behavior is shaped by experience varies between individuals. Genetic differences contribute to this variation, but the neural mechanisms are not understood. Here, we dissect natural variation in the behavioral flexibility of two Caenorhabditis elegans wild strains. In one strain, a memory of exposure to 21% O2 suppresses CO2-evoked locomotory arousal; in the other, CO2 evokes arousal regardless of previous O2 experience. We map that variation to a polymorphic dendritic scaffold protein, ARCP-1, expressed in sensory neurons. ARCP-1 binds the Ca2+-dependent phosphodiesterase PDE-1 and co-localizes PDE-1 with molecular sensors for CO2 at dendritic ends. Reducing ARCP-1 or PDE-1 activity promotes CO2 escape by altering neuropeptide expression in the BAG CO2 sensors. Variation in ARCP-1 alters behavioral plasticity in multiple paradigms. Our findings are reminiscent of genetic accommodation, an evolutionary process by which phenotypic flexibility in response to environmental variation is reset by genetic change. Behavioral flexibility varies across Caenorhabditis and C. elegans wild isolates A natural polymorphism in ARCP-1 underpins inter-individual variation in plasticity ARCP-1 is a dendritic scaffold protein localizing cGMP signaling machinery to cilia Disrupting ARCP-1 alters behavioral plasticity by changing neuropeptide expression
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Affiliation(s)
- Isabel Beets
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Gaotian Zhang
- Institut de Biologie de l'École Normale Supérieure, CNRS, Inserm, PSL Research University, Paris 75005, France
| | - Lorenz A Fenk
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Changchun Chen
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Geoffrey M Nelson
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Marie-Anne Félix
- Institut de Biologie de l'École Normale Supérieure, CNRS, Inserm, PSL Research University, Paris 75005, France.
| | - Mario de Bono
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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28
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Proulx SR, Dey S, Guzella T, Teotónio H. How differing modes of non-genetic inheritance affect population viability in fluctuating environments. Ecol Lett 2019; 22:1767-1775. [PMID: 31436016 DOI: 10.1111/ele.13355] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/30/2019] [Accepted: 07/01/2019] [Indexed: 12/28/2022]
Abstract
Different modes of non-genetic inheritance are expected to affect population persistence in fluctuating environments. We here analyse Caenorhabditis elegans density-independent per capita growth rate time series on 36 populations experiencing six controlled sequences of challenging oxygen level fluctuations across 60 generations, and parameterise competing models of non-genetic inheritance in order to explain observed dynamics. Our analysis shows that phenotypic plasticity and anticipatory maternal effects are sufficient to explain growth rate dynamics, but that a carryover model where 'epigenetic' memory is imperfectly transmitted and might be reset at each generation is a better fit to the data. We further find that this epigenetic memory is asymmetric since it is kept for longer when populations are exposed to the more challenging environment. Our analysis suggests that population persistence in fluctuating environments depends on the non-genetic inheritance of phenotypes whose expression is regulated across multiple generations.
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Affiliation(s)
- Stephen R Proulx
- Department of Ecology, Evolution, and Marine Biology, UC Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Snigdhadip Dey
- Institut de Biologie de L'École Normale Suṕerieure, CNRS, Inserm, PSL Research University, F-75005, Paris, France
| | - Thiago Guzella
- Institut de Biologie de L'École Normale Suṕerieure, CNRS, Inserm, PSL Research University, F-75005, Paris, France
| | - Henrique Teotónio
- Institut de Biologie de L'École Normale Suṕerieure, CNRS, Inserm, PSL Research University, F-75005, Paris, France
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29
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Snoek BL, Volkers RJM, Nijveen H, Petersen C, Dirksen P, Sterken MG, Nakad R, Riksen JAG, Rosenstiel P, Stastna JJ, Braeckman BP, Harvey SC, Schulenburg H, Kammenga JE. A multi-parent recombinant inbred line population of C. elegans allows identification of novel QTLs for complex life history traits. BMC Biol 2019; 17:24. [PMID: 30866929 PMCID: PMC6417139 DOI: 10.1186/s12915-019-0642-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 02/26/2019] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND The nematode Caenorhabditis elegans has been extensively used to explore the relationships between complex traits, genotypes, and environments. Complex traits can vary across different genotypes of a species, and the genetic regulators of trait variation can be mapped on the genome using quantitative trait locus (QTL) analysis of recombinant inbred lines (RILs) derived from genetically and phenotypically divergent parents. Most RILs have been derived from crossing two parents from globally distant locations. However, the genetic diversity between local C. elegans populations can be as diverse as between global populations and could thus provide means of identifying genetic variation associated with complex traits relevant on a broader scale. RESULTS To investigate the effect of local genetic variation on heritable traits, we developed a new RIL population derived from 4 parental wild isolates collected from 2 closely located sites in France: Orsay and Santeuil. We crossed these 4 genetically diverse parental isolates to generate a population of 200 multi-parental RILs and used RNA-seq to obtain sequence polymorphisms identifying almost 9000 SNPs variable between the 4 genotypes with an average spacing of 11 kb, doubling the mapping resolution relative to currently available RIL panels for many loci. The SNPs were used to construct a genetic map to facilitate QTL analysis. We measured life history traits such as lifespan, stress resistance, developmental speed, and population growth in different environments, and found substantial variation for most traits. We detected multiple QTLs for most traits, including novel QTLs not found in previous QTL analysis, including those for lifespan and pathogen responses. This shows that recombining genetic variation across C. elegans populations that are in geographical close proximity provides ample variation for QTL mapping. CONCLUSION Taken together, we show that using more parents than the classical two parental genotypes to construct a RIL population facilitates the detection of QTLs and that the use of wild isolates facilitates the detection of QTLs. The use of multi-parent RIL populations can further enhance our understanding of local adaptation and life history trade-offs.
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Affiliation(s)
- Basten L Snoek
- Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, NL-6708 PB, Wageningen, The Netherlands. .,Theoretical Biology and Bioinformatics, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
| | - Rita J M Volkers
- Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, NL-6708 PB, Wageningen, The Netherlands
| | - Harm Nijveen
- Bioinformatics Group, Wageningen University, Droevendaalsesteeg 1, NL-6708 PB, Wageningen, The Netherlands
| | - Carola Petersen
- Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Philipp Dirksen
- Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Mark G Sterken
- Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, NL-6708 PB, Wageningen, The Netherlands
| | - Rania Nakad
- Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Joost A G Riksen
- Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, NL-6708 PB, Wageningen, The Netherlands
| | - Philip Rosenstiel
- Institute for Clinical Molecular Biology, University of Kiel, 24098, Kiel, Germany
| | - Jana J Stastna
- Biomolecular Research Group, School of Human and Life Sciences, Canterbury Christ Church University, North Holmes Road, Canterbury, CT1 1QU, UK
| | - Bart P Braeckman
- Department of Biology, Ghent University, K. L. Ledeganckstraat 35, B-9000, Ghent, Belgium
| | - Simon C Harvey
- Biomolecular Research Group, School of Human and Life Sciences, Canterbury Christ Church University, North Holmes Road, Canterbury, CT1 1QU, UK
| | - Hinrich Schulenburg
- Zoological Institute, University of Kiel, 24098, Kiel, Germany. .,Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306, Plön, Germany.
| | - Jan E Kammenga
- Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, NL-6708 PB, Wageningen, The Netherlands.
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30
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Perez MF, Lehner B. Intergenerational and transgenerational epigenetic inheritance in animals. Nat Cell Biol 2019; 21:143-151. [PMID: 30602724 DOI: 10.1038/s41556-018-0242-9] [Citation(s) in RCA: 291] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/29/2018] [Indexed: 12/12/2022]
Abstract
Animals transmit not only DNA but also other molecules, such as RNA, proteins and metabolites, to their progeny via gametes. It is currently unclear to what extent these molecules convey information between generations and whether this information changes according to their physiological state and environment. Here, we review recent work on the molecular mechanisms by which 'epigenetic' information is transmitted between generations over different timescales, and the importance of this information for development and physiology.
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Affiliation(s)
- Marcos Francisco Perez
- Systems Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Ben Lehner
- Systems Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain. .,Universitat Pompeu Fabra (UPF), Barcelona, Spain. .,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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