1
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Piñeiro López C, Rodrigues Neves AR, Čavka I, Gros OJ, Köhler S. Segmentation of C. elegans germline nuclei. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.001062. [PMID: 38148986 PMCID: PMC10750166 DOI: 10.17912/micropub.biology.001062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 12/28/2023]
Abstract
Immunofluorescence microscopy is a widely adopted method for studying meiotic prophase in the nematode model organism, Caenorhabditis elegans . An in-depth examination of specific meiotic processes requires the quantitative analysis of immunofluorescence images, which often involves the segmentation of individual cells or nuclei. Here, we introduce our image analysis pipeline to automate significant portions of this task. This pipeline relies on the powerful deep learning model Cellpose 2.0 to segment cellular structures. To further improve the segmentation accuracy for germline nuclei stained for chromatin or synaptonemal complexes, we retrained the generalist Cellpose model and integrated our data processing pipeline into the easy-to-use Cell-ACDC image analysis software. Our pipeline thus makes deep learning-based segmentation of nuclei in the distal germline of C. elegans accessible for users without coding experience.
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Affiliation(s)
- Cristina Piñeiro López
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
| | - Ana Rita Rodrigues Neves
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Ivana Čavka
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Oane Jan Gros
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
| | - Simone Köhler
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
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2
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Huang YC, Luo J, Huang W, Baker CM, Gomes MA, Byrne AB, Flavell SW. A single neuron in C. elegans orchestrates multiple motor outputs through parallel modes of transmission. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.02.532814. [PMID: 37034579 PMCID: PMC10081309 DOI: 10.1101/2023.04.02.532814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Animals generate a wide range of highly coordinated motor outputs, which allows them to execute purposeful behaviors. Individual neuron classes in the circuits that generate behavior have a remarkable capacity for flexibility, as they exhibit multiple axonal projections, transmitter systems, and modes of neural activity. How these multi-functional properties of neurons enable the generation of highly coordinated behaviors remains unknown. Here we show that the HSN neuron in C. elegans evokes multiple motor programs over different timescales to enable a suite of behavioral changes during egg-laying. Using HSN activity perturbations and in vivo calcium imaging, we show that HSN acutely increases egg-laying and locomotion while also biasing the animals towards low-speed dwelling behavior over longer timescales. The acute effects of HSN on egg-laying and high-speed locomotion are mediated by separate sets of HSN transmitters and different HSN axonal projections. The long-lasting effects on dwelling are mediated by HSN release of serotonin that is taken up and re-released by NSM, another serotonergic neuron class that directly evokes dwelling. Our results show how the multi-functional properties of a single neuron allow it to induce a coordinated suite of behaviors and also reveal for the first time that neurons can borrow serotonin from one another to control behavior.
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Affiliation(s)
- Yung-Chi Huang
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jinyue Luo
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Wenjia Huang
- Department of Neurobiology, UMass Chan Medical School, Worcester, MA, USA
| | - Casey M. Baker
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew A. Gomes
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Alexandra B. Byrne
- Department of Neurobiology, UMass Chan Medical School, Worcester, MA, USA
| | - Steven W. Flavell
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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3
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Sanfeliu-Cerdán N, Lin LC, Dunn AR, Goodman MB, Krieg M. Visualizing Neurons Under Tension In Vivo with Optogenetic Molecular Force Sensors. Methods Mol Biol 2023; 2600:239-266. [PMID: 36587102 DOI: 10.1007/978-1-0716-2851-5_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The visualization of mechanical stress distribution in specific molecular networks within a living and physiologically active cell or animal remains a formidable challenge in mechanobiology. The advent of fluorescence-resonance energy transfer (FRET)-based molecular tension sensors overcame a significant hurdle that now enables us to address previously technically limited questions. Here, we describe a method that uses genetically encoded FRET tension sensors to visualize the mechanics of cytoskeletal networks in neurons of living animals with sensitized emission FRET and confocal scanning light microscopy. This method uses noninvasive immobilization of living animals to image neuronal β-spectrin cytoskeleton at the diffraction limit, and leverages multiple imaging controls to verify and underline the quality of the measurements. In combination with a semiautomated machine-vision algorithm to identify and trace individual neurites, our analysis performs simultaneous calculation of FRET efficiencies and visualizes statistical uncertainty on a pixel by pixel basis. Our approach is not limited to genetically encoded spectrin tension sensors, but can also be used for any kind of ratiometric imaging in neuronal cells both in vivo and in vitro.
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Affiliation(s)
- Neus Sanfeliu-Cerdán
- Neurophotonics and Mechanical Systems Biology, ICFO, Institut de Ciències Fotòniques, ICFO, Castelldefels, Spain
| | - Li-Chun Lin
- Neurophotonics and Mechanical Systems Biology, ICFO, Institut de Ciències Fotòniques, ICFO, Castelldefels, Spain
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Miriam B Goodman
- Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
| | - Michael Krieg
- Neurophotonics and Mechanical Systems Biology, ICFO, Institut de Ciències Fotòniques, ICFO, Castelldefels, Spain.
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Bhandari N, Pfeiffer SC, Jaramillo-Lambert A. Characterization of N- and C-terminal endogenously tagged Tyrosyl-DNA phosphodiesterase 2 (TDPT-1) C. elegans strains. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000540. [PMID: 35622466 PMCID: PMC9010224 DOI: 10.17912/micropub.biology.000540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/10/2022] [Accepted: 03/14/2022] [Indexed: 11/09/2022]
Abstract
We have generated Tyrosyl-DNA phosphodiesterase 2 (TDPT-1) C. elegans strains where CRISPR/Cas9 was used to endogenously tag the protein at either the C- or N-terminus and validated the functionality of the resulting tagged TDPT-1 proteins. We have found that both the N-terminally tagged ( wrmScarlet::tdpt-1) and C-terminally tagged ( tdpt-1::3xflag ) worm TDPT-1 does not affect embryonic viability compared to wild type. Using the N-terminally tagged wrmScarlet::tdpt-1 strain we show, for the first time, that TDPT-1 is expressed in nuclei of the germ line and the soma. Moreover, we validate the expression of TDPT-1 at the protein level using the C-terminally tagged ( tdpt-1::3xflag ) strain.
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Seirin-Lee S, Yamamoto K, Kimura A. The extra-embryonic space and the local contour are crucial geometric constraints regulating cell arrangement. Development 2022; 149:275369. [PMID: 35552395 PMCID: PMC9148568 DOI: 10.1242/dev.200401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 03/23/2022] [Indexed: 12/29/2022]
Abstract
In multicellular systems, cells communicate with adjacent cells to determine their positions and fates, an arrangement important for cellular development. Orientation of cell division, cell-cell interactions (i.e. attraction and repulsion) and geometric constraints are three major factors that define cell arrangement. In particular, geometric constraints are difficult to reveal in experiments, and the contribution of the local contour of the boundary has remained elusive. In this study, we developed a multicellular morphology model based on the phase-field method so that precise geometric constraints can be incorporated. Our application of the model to nematode embryos predicted that the amount of extra-embryonic space, the empty space within the eggshell that is not occupied by embryonic cells, affects cell arrangement in a manner dependent on the local contour and other factors. The prediction was validated experimentally by increasing the extra-embryonic space in the Caenorhabditis elegans embryo. Overall, our analyses characterized the roles of geometrical contributors, specifically the amount of extra-embryonic space and the local contour, on cell arrangements. These factors should be considered for multicellular systems. Summary: The local contour and the extra-embryonic space, the empty space within the eggshell not occupied by embryonic cells, are important geometric constraints in cell arrangement of nematode embryos.
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Affiliation(s)
- Sungrim Seirin-Lee
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University Institute for Advanced Study, Kyoto University, Kyoto 606-8315, Japan.,JST CREST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Kazunori Yamamoto
- Department of Applied Bioscience, Faculty of Applied Bioscience, Kanagawa Institute of Technology, Atsugi 243-0292, Japan
| | - Akatsuki Kimura
- Cell Architecture Laboratory, Department of Chromosome Science, National Institute of Genetics, Mishima 411-8540, Japan.,Department of Genetics, The Graduate University for Advanced Studies, Sokendai, Mishima 411-8540, Japan
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Cahoon CK, Libuda DE. Conditional immobilization for live imaging Caenorhabditis elegans using auxin-dependent protein depletion. G3-GENES GENOMES GENETICS 2021; 11:6362942. [PMID: 34534266 PMCID: PMC8527506 DOI: 10.1093/g3journal/jkab310] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 08/19/2021] [Indexed: 11/12/2022]
Abstract
The visualization of biological processes using fluorescent proteins and dyes in living organisms has enabled numerous scientific discoveries. The nematode Caenorhabditis elegans is a widely used model organism for live imaging studies since the transparent nature of the worm enables imaging of nearly all tissues within a whole, intact animal. While current techniques are optimized to enable the immobilization of hermaphrodite worms for live imaging, many of these approaches fail to successfully restrain the smaller male worms. To enable live imaging of worms of both sexes, we developed a new genetic, conditional immobilization tool that uses the auxin-inducible degron (AID) system to immobilize both adult and larval hermaphrodite and male worms for live imaging. Based on chromosome location, mutant phenotype, and predicted germline consequence, we identified and AID-tagged three candidate genes (unc-18, unc-104, and unc-52). Strains with these AID-tagged genes were placed on auxin and tested for mobility and germline defects. Among the candidate genes, auxin-mediated depletion of UNC-18 caused significant immobilization of both hermaphrodite and male worms that was also partially reversible upon removal from auxin. Notably, we found that male worms require a higher concentration of auxin for a similar amount of immobilization as hermaphrodites, thereby suggesting a potential sex-specific difference in auxin absorption and/or processing. In both males and hermaphrodites, depletion of UNC-18 did not largely alter fertility, germline progression, nor meiotic recombination. Finally, we demonstrate that this new genetic tool can successfully immobilize both sexes enabling live imaging studies of sexually dimorphic features in C. elegans.
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Affiliation(s)
- Cori K Cahoon
- Department of Biology, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403-1229, USA
| | - Diana E Libuda
- Department of Biology, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403-1229, USA
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7
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Zellag RM, Zhao Y, Poupart V, Singh R, Labbé JC, Gerhold AR. CentTracker: a trainable, machine-learning-based tool for large-scale analyses of Caenorhabditis elegans germline stem cell mitosis. Mol Biol Cell 2021; 32:915-930. [PMID: 33502892 PMCID: PMC8108535 DOI: 10.1091/mbc.e20-11-0716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Investigating the complex interactions between stem cells and their native environment requires an efficient means to image them in situ. Caenorhabditis elegans germline stem cells (GSCs) are distinctly accessible for intravital imaging; however, long-term image acquisition and analysis of dividing GSCs can be technically challenging. Here we present a systematic investigation into the technical factors impacting GSC physiology during live imaging and provide an optimized method for monitoring GSC mitosis under minimally disruptive conditions. We describe CentTracker, an automated and generalizable image analysis tool that uses machine learning to pair mitotic centrosomes and that can extract a variety of mitotic parameters rapidly from large-scale data sets. We employ CentTracker to assess a range of mitotic features in a large GSC data set. We observe spatial clustering of mitoses within the germline tissue but no evidence that subpopulations with distinct mitotic profiles exist within the stem cell pool. We further find biases in GSC spindle orientation relative to the germline’s distal–proximal axis and thus the niche. The technical and analytical tools provided herein pave the way for large-scale screening studies of multiple mitotic processes in GSCs dividing in situ, in an intact tissue, in a living animal, under seemingly physiological conditions.
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Affiliation(s)
- Réda M Zellag
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada.,Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Yifan Zhao
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada.,Present address: Harvard-MIT Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, MA 02139
| | - Vincent Poupart
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Ramya Singh
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada.,Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Jean-Claude Labbé
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Abigail R Gerhold
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada
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Fabig G, Löffler F, Götze C, Müller-Reichert T. Live-cell Imaging and Quantitative Analysis of Meiotic Divisions in Caenorhabditis elegans Males. Bio Protoc 2020; 10:e3785. [PMID: 33659440 DOI: 10.21769/bioprotoc.3785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/30/2020] [Accepted: 09/21/2020] [Indexed: 11/02/2022] Open
Abstract
Live-imaging of meiotic cell division has been performed in extracted spermatocytes of a number of species using phase-contrast microscopy. For the nematode Caenorhabditis elegans, removal of spermatocytes from gonads has damaging effects, as most of the extracted spermatocytes show a high variability in the timing of meiotic divisions or simply arrest during the experiment. Therefore, we developed a live-cell imaging approach for in situ filming of spermatocyte meiosis in whole immobilized C. elegans males, thus allowing an observation of male germ cells within an unperturbed environment. For this, we make use of strains with fluorescently labeled chromosomes and centrosomes. Here we describe how to immobilize male worms for live-imaging. Further, we describe the workflow for the acquisition and processing of data to obtain quantitative information about the dynamics of chromosome segregation in spermatocyte meiosis I and II. In addition, our newly developed approach allows us to re-orient filmed spindles in silico, regardless of the initial 3D orientation in the worm, and analyze spindle dynamics in living worms in a statistically robust manner. Our live-imaging approach is also applicable to C. elegans hermaphrodites and should be expandable to other fluorescently labelled nematodes or other fully transparent small model organisms.
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Affiliation(s)
- Gunar Fabig
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | | | | | - Thomas Müller-Reichert
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
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