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Docampo R. Advances in the cellular biology, biochemistry, and molecular biology of acidocalcisomes. Microbiol Mol Biol Rev 2024; 88:e0004223. [PMID: 38099688 PMCID: PMC10966946 DOI: 10.1128/mmbr.00042-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2024] Open
Abstract
SUMMARYAcidocalcisomes are organelles conserved during evolution and closely related to the so-called volutin granules of bacteria and archaea, to the acidocalcisome-like vacuoles of yeasts, and to the lysosome-related organelles of animal species. All these organelles have in common their acidity and high content of polyphosphate and calcium. They are characterized by a variety of functions from storage of phosphorus and calcium to roles in Ca2+ signaling, osmoregulation, blood coagulation, and inflammation. They interact with other organelles through membrane contact sites or by fusion, and have several enzymes, pumps, transporters, and channels.
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Affiliation(s)
- Roberto Docampo
- Department of Cellular Biology, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
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2
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Tashyreva D, Týč J, Horák A, Lukeš J. Ultrastructure and 3D reconstruction of a diplonemid protist (Diplonemea) and its novel membranous organelle. mBio 2023; 14:e0192123. [PMID: 37737610 PMCID: PMC10653844 DOI: 10.1128/mbio.01921-23] [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: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 09/23/2023] Open
Abstract
IMPORTANCE The knowledge of cell biology of a eukaryotic group is essential for correct interpretation of ecological and molecular data. Although diplonemid protists are one of the most species-rich lineages of marine eukaryotes, only very fragmentary information is available about the cellular architecture of this taxonomically diverse group. Here, a large serial block-face scanning electron microscopy data set complemented with light and fluorescence microscopy allowed the first detailed three-dimensional reconstruction of a diplonemid species. We describe numerous previously unknown peculiarities of the cellular architecture and cell division characteristic for diplonemid flagellates, and illustrate the obtained results with multiple three-dimensional models, comprehensible for non-specialists in protist ultrastructure.
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Affiliation(s)
- Daria Tashyreva
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Jiří Týč
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Aleš Horák
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Sciences, University of South Bohemia, České Budějovice, Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Sciences, University of South Bohemia, České Budějovice, Czech Republic
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3
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Burrell A, Marugan-Hernandez V, Graefin Von Der Recke K, Aguiar-Martins K, Gabriel HB, Tomley FM, Vaughan S. Refractile bodies of Eimeria tenella are proteinaceous membrane-less organelles that undergo dynamic changes during infection. Front Cell Infect Microbiol 2023; 13:1082622. [PMID: 37033474 PMCID: PMC10081493 DOI: 10.3389/fcimb.2023.1082622] [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: 10/28/2022] [Accepted: 02/27/2023] [Indexed: 03/11/2023] Open
Abstract
IntroductionRefractile bodies (RB) are large membrane-less organelles (MLO) of unknown function found as a prominent mismatched pair within the sporozoite stages of all species of Eimeria, parasitic coccidian protozoa.MethodsHigh resolution imaging methods including time-lapse live confocal microscopy and serial block face-scanning electron microscopy (SBF-SEM) were used to investigate the morphology of RB and other intracellular organelles before and after sporozoite invasion of host cells.ResultsLive cell imaging of MDBK cells infected with E. tenella sporozoites confirmed previous reports that RB reduce from two to one post-infection and showed that reduction in RB number occurs via merger of the anterior RB with the posterior RB, a process that lasts 20-40 seconds and takes place between 2- and 5-hours post-infection. Ultrastructural studies using SBF-SEM on whole individual sporozoites, both pre- and post-host cell invasion, confirmed the live cell imaging observations and showed also that changes to the overall sporozoite cell shape accompanied RB merger. Furthermore, the single RB post-merger was found to be larger in volume than the two RB pre-merger. Actin inhibitors were used to investigate a potential role for actin in RB merger, Cytochalasin D significantly inhibited both RB merger and the accompanying changes in sporozoite cell shape.DiscussionMLOs in eukaryotic organisms are characterised by their lack of a membrane and ability to undergo liquid-liquid phase separation (LLPS) and fusion, usually in an actin-mediated fashion. Based on the changes in sporozoite cell shape observed at the time of RB merger together with a potential role for actin in this process, we propose that RB are classed as an MLO and recognised as one of the largest MLOs so far characterised.
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Affiliation(s)
- Alana Burrell
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
- Department of Pathobiology and Population Sciences, The Royal Veterinary College, University of London, North Mymms, United Kingdom
| | - Virginia Marugan-Hernandez
- Department of Pathobiology and Population Sciences, The Royal Veterinary College, University of London, North Mymms, United Kingdom
- *Correspondence: Virginia Marugan-Hernandez, ; Sue Vaughan,
| | - Karolin Graefin Von Der Recke
- Department of Pathobiology and Population Sciences, The Royal Veterinary College, University of London, North Mymms, United Kingdom
| | - Kelsilandia Aguiar-Martins
- Department of Pathobiology and Population Sciences, The Royal Veterinary College, University of London, North Mymms, United Kingdom
| | - Heloisa Berti Gabriel
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Fiona M. Tomley
- Department of Pathobiology and Population Sciences, The Royal Veterinary College, University of London, North Mymms, United Kingdom
| | - Sue Vaughan
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
- *Correspondence: Virginia Marugan-Hernandez, ; Sue Vaughan,
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4
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Smithson L, Ihuoma Akazue P, Findlater L, Gwira TM, Vaughan S, Sunter JD. Diversity in new flagellum tip attachment in bloodstream form African trypanosomes. Mol Microbiol 2022; 118:510-525. [PMID: 36056717 PMCID: PMC9826329 DOI: 10.1111/mmi.14979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 01/11/2023]
Abstract
The closely related parasites Trypanosoma brucei, T. congolense, and T. vivax cause neglected tropical diseases collectively known as African Trypanosomiasis. A characteristic feature of bloodstream form T. brucei is the flagellum that is laterally attached to the side of the cell body. During the cell cycle, the new flagellum is formed alongside the old flagellum, with the new flagellum tip embedded within a mobile transmembrane junction called the groove. The molecular composition of the groove is currently unknown, which limits the analysis of this junction and assessment of its conservation in related trypanosomatids. Here, we identified 13 proteins that localize to the flagellar groove through a small-scale tagging screen. Functional analysis of a subset of these proteins by RNAi and gene deletion revealed three proteins, FCP4/TbKin15, FCP7, and FAZ45, that are involved in new flagellum tip attachment to the groove. Despite possessing orthologues of all 13 groove proteins, T. congolense and T. vivax did not assemble a canonical groove around the new flagellum tip according to 3D electron microscopy. This diversity in new flagellum tip attachment points to the rapid evolution of membrane-cytoskeleton structures that can occur without large changes in gene complement and likely reflects the niche specialization of each species.
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Affiliation(s)
- Laura Smithson
- Department of Biological and Medical SciencesOxford Brookes UniversityOxfordUK
| | - Pearl Ihuoma Akazue
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied SciencesUniversity of GhanaAccraGhana,Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied SciencesUniversity of GhanaAccraGhana,Department of Biochemistry, Faculty of Life SciencesUniversity of BeninBenin CityNigeria
| | - Lucy Findlater
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Theresa Manful Gwira
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied SciencesUniversity of GhanaAccraGhana,Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied SciencesUniversity of GhanaAccraGhana
| | - Sue Vaughan
- Department of Biological and Medical SciencesOxford Brookes UniversityOxfordUK
| | - Jack D. Sunter
- Department of Biological and Medical SciencesOxford Brookes UniversityOxfordUK
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5
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Kievits AJ, Lane R, Carroll EC, Hoogenboom JP. How innovations in methodology offer new prospects for volume electron microscopy. J Microsc 2022; 287:114-137. [PMID: 35810393 PMCID: PMC9546337 DOI: 10.1111/jmi.13134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 06/29/2022] [Accepted: 07/06/2022] [Indexed: 11/29/2022]
Abstract
Detailed knowledge of biological structure has been key in understanding biology at several levels of organisation, from organs to cells and proteins. Volume electron microscopy (volume EM) provides high resolution 3D structural information about tissues on the nanometre scale. However, the throughput rate of conventional electron microscopes has limited the volume size and number of samples that can be imaged. Recent improvements in methodology are currently driving a revolution in volume EM, making possible the structural imaging of whole organs and small organisms. In turn, these recent developments in image acquisition have created or stressed bottlenecks in other parts of the pipeline, like sample preparation, image analysis and data management. While the progress in image analysis is stunning due to the advent of automatic segmentation and server‐based annotation tools, several challenges remain. Here we discuss recent trends in volume EM, emerging methods for increasing throughput and implications for sample preparation, image analysis and data management.
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Affiliation(s)
- Arent J. Kievits
- Imaging Physics Delft University of Technology Delft 2624CJ The Netherlands
| | - Ryan Lane
- Imaging Physics Delft University of Technology Delft 2624CJ The Netherlands
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6
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Ramanantsalama MR, Landrein N, Casas E, Salin B, Blancard C, Bonhivers M, Robinson DR, Dacheux D. TFK1, a basal body transition fibre protein that is essential for cytokinesis in Trypanosoma brucei. J Cell Sci 2022; 135:275643. [PMID: 35588197 DOI: 10.1242/jcs.259893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 05/12/2022] [Indexed: 11/20/2022] Open
Abstract
In Trypanosoma brucei, transition fibres (TF) form a nine-bladed pattern-like structure connecting the base of the flagellum to the flagellar pocket membrane. Despite the characterization of two TF proteins, CEP164C and TbRP2, little is known about the organization of these fibres. Here, we report the identification and characterization of the first kinetoplastid-specific TF protein named TFK1 (Tb927.6.1180). Bioinformatics and functional domain analysis identified three TFK1 distinct domains: an N-terminal domain of an unpredicted function, a coiled-coil domain involved in TFK1-TFK1 interaction and a C-terminal intrinsically disordered region potentially involved in protein interaction. Cellular immuno-localization showed that TFK1 is a newly identified basal body maturation marker. Further, using ultrastructure expansion and immuno-electron microscopies we localized CEP164C and TbRP2 at the TF and TFK1 on the distal appendage matrix of the TF. Importantly, RNAi knockdown of TFK1 in bloodstream form cells induced misplacement of basal bodies, a defect in the furrow or fold generation and eventually cell death. We hypothesize that TFK1 is a basal body positioning specific actor and a key regulator of cytokinesis in the bloodstream form Trypanosoma brucei.
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Affiliation(s)
| | - Nicolas Landrein
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Elina Casas
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Bénédicte Salin
- University of Bordeaux, CNRS, Microscopy Department IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Corinne Blancard
- University of Bordeaux, CNRS, Microscopy Department IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Mélanie Bonhivers
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Derrick R Robinson
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Denis Dacheux
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France.,Bordeaux INP, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
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7
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Li M, Gaussmann S, Tippler B, Ott J, Popowicz GM, Schliebs W, Sattler M, Erdmann R, Kalel VC. Novel Trypanocidal Inhibitors that Block Glycosome Biogenesis by Targeting PEX3-PEX19 Interaction. Front Cell Dev Biol 2022; 9:737159. [PMID: 34988071 PMCID: PMC8721105 DOI: 10.3389/fcell.2021.737159] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 11/15/2021] [Indexed: 12/02/2022] Open
Abstract
Human pathogenic trypanosomatid parasites harbor a unique form of peroxisomes termed glycosomes that are essential for parasite viability. We and others previously identified and characterized the essential Trypanosoma brucei ortholog TbPEX3, which is the membrane-docking factor for the cytosolic receptor PEX19 bound to the glycosomal membrane proteins. Knockdown of TbPEX3 expression leads to mislocalization of glycosomal membrane and matrix proteins, and subsequent cell death. As an early step in glycosome biogenesis, the PEX3–PEX19 interaction is an attractive drug target. We established a high-throughput assay for TbPEX3–TbPEX19 interaction and screened a compound library for small-molecule inhibitors. Hits from the screen were further validated using an in vitro ELISA assay. We identified three compounds, which exhibit significant trypanocidal activity but show no apparent toxicity to human cells. Furthermore, we show that these compounds lead to mislocalization of glycosomal proteins, which is toxic to the trypanosomes. Moreover, NMR-based experiments indicate that the inhibitors bind to PEX3. The inhibitors interfering with glycosomal biogenesis by targeting the TbPEX3–TbPEX19 interaction serve as starting points for further optimization and anti-trypanosomal drug development.
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Affiliation(s)
- Mengqiao Li
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Stefan Gaussmann
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Department of Chemistry, Bavarian NMR Center, Technical University of Munich, Garching, Germany
| | - Bettina Tippler
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Julia Ott
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Grzegorz M Popowicz
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Department of Chemistry, Bavarian NMR Center, Technical University of Munich, Garching, Germany
| | - Wolfgang Schliebs
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Department of Chemistry, Bavarian NMR Center, Technical University of Munich, Garching, Germany
| | - Ralf Erdmann
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Vishal C Kalel
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
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8
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Cytosolic and Mitochondrial Hsp90 in Cytokinesis, Mitochondrial DNA Replication, and Drug Action in Trypanosoma brucei. Antimicrob Agents Chemother 2021; 65:e0063221. [PMID: 34424040 DOI: 10.1128/aac.00632-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Trypanosoma brucei subspecies cause African sleeping sickness in humans, an infection that is commonly fatal if not treated, and available therapies are limited. Previous studies have shown that heat shock protein 90 (Hsp90) inhibitors have potent and vivid activity against bloodstream-form trypanosomes. Hsp90s are phylogenetically conserved and essential catalysts that function at the crux of cell biology, where they ensure the proper folding of proteins and their assembly into multicomponent complexes. To assess the specificity of Hsp90 inhibitors and further define the role of Hsp90s in African trypanosomes, we used RNA interference (RNAi) to knock down cytosolic and mitochondrial Hsp90s (HSP83 and HSP84, respectively). Loss of either protein led to cell death, but the phenotypes were distinctly different. Depletion of cytosolic HSP83 closely mimicked the consequences of chemically depleting Hsp90 activity with inhibitor 17-AAG. In these cells, cytokinesis was severely disrupted, and segregation of the kinetoplast (the massive mitochondrial DNA structure unique to this family of eukaryotic pathogens) was impaired, leading to cells with abnormal kinetoplast DNA (kDNA) structures. Quite differently, knockdown of mitochondrial HSP84 did not impair cytokinesis but halted the initiation of new kDNA synthesis, generating cells without kDNA. These findings highlight the central role of Hsp90s in chaperoning cell cycle regulators in trypanosomes, reveal their unique function in kinetoplast replication, and reinforce their specificity and value as drug targets.
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9
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Campbell PC, de Graffenried CL. Alternate histories of cytokinesis: lessons from the trypanosomatids. Mol Biol Cell 2021; 31:2631-2639. [PMID: 33180676 PMCID: PMC7927182 DOI: 10.1091/mbc.e19-12-0696] [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] [Indexed: 12/04/2022] Open
Abstract
Popular culture has recently produced several “alternate histories” that describe worlds where key historical events had different outcomes. Beyond entertainment, asking “could this have happened a different way?” and “what would the consequences be?” are valuable approaches for exploring molecular mechanisms in many areas of research, including cell biology. Analogous to alternate histories, studying how the evolutionary trajectories of related organisms have been selected to provide a range of outcomes can tell us about the plasticity and potential contained within the genome of the ancestral cell. Among eukaryotes, a group of model organisms has been employed with great success to identify a core, conserved framework of proteins that segregate the duplicated cellular organelles into two daughter cells during cell division, a process known as cytokinesis. However, these organisms provide relatively sparse sampling across the broad evolutionary distances that exist, which has limited our understanding of the true potential of the ancestral eukaryotic toolkit. Recent work on the trypanosomatids, a group of eukaryotic parasites, exemplifies alternate historical routes for cytokinesis that illustrate the range of eukaryotic diversity, especially among unicellular organisms.
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Affiliation(s)
- Paul C Campbell
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912
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10
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Dean S. Basic Biology of Trypanosoma brucei with Reference to the Development of Chemotherapies. Curr Pharm Des 2021; 27:1650-1670. [PMID: 33463458 DOI: 10.2174/1381612827666210119105008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/01/2020] [Accepted: 12/08/2020] [Indexed: 11/22/2022]
Abstract
Trypanosoma brucei are protozoan parasites that cause the lethal human disease African sleeping sickness and the economically devastating disease of cattle, Nagana. African sleeping sickness, also known as Human African Trypanosomiasis (HAT), threatens 65 million people and animal trypanosomiasis makes large areas of farmland unusable. There is no vaccine and licensed therapies against the most severe, late-stage disease are toxic, impractical and ineffective. Trypanosomes are transmitted by tsetse flies, and HAT is therefore predominantly confined to the tsetse fly belt in sub-Saharan Africa. They are exclusively extracellular and they differentiate between at least seven developmental forms that are highly adapted to host and vector niches. In the mammalian (human) host they inhabit the blood, cerebrospinal fluid (late-stage disease), skin, and adipose fat. In the tsetse fly vector they travel from the tsetse midgut to the salivary glands via the ectoperitrophic space and proventriculus. Trypanosomes are evolutionarily divergent compared with most branches of eukaryotic life. Perhaps most famous for their extraordinary mechanisms of monoallelic gene expression and antigenic variation, they have also been investigated because much of their biology is either highly unconventional or extreme. Moreover, in addition to their importance as pathogens, many researchers have been attracted to the field because trypanosomes have some of the most advanced molecular genetic tools and database resources of any model system. The following will cover just some aspects of trypanosome biology and how its divergent biochemistry has been leveraged to develop drugs to treat African sleeping sickness. This is by no means intended to be a comprehensive survey of trypanosome features. Rather, I hope to present trypanosomes as one of the most fascinating and tractable systems to do discovery biology.
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Affiliation(s)
- Samuel Dean
- Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom
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11
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The Trypanosome UDP-Glucose Pyrophosphorylase Is Imported by Piggybacking into Glycosomes, Where Unconventional Sugar Nucleotide Synthesis Takes Place. mBio 2021; 12:e0037521. [PMID: 34044588 PMCID: PMC8262884 DOI: 10.1128/mbio.00375-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Glycosomes are peroxisome-related organelles of trypanosomatid parasites containing metabolic pathways, such as glycolysis and biosynthesis of sugar nucleotides, usually present in the cytosol of other eukaryotes. UDP-glucose pyrophosphorylase (UGP), the enzyme responsible for the synthesis of the sugar nucleotide UDP-glucose, is localized in the cytosol and glycosomes of the bloodstream and procyclic trypanosomes, despite the absence of any known peroxisome-targeting signal (PTS1 and PTS2). The questions that we address here are (i) is the unusual glycosomal biosynthetic pathway of sugar nucleotides functional and (ii) how is the PTS-free UGP imported into glycosomes? We showed that UGP is imported into glycosomes by piggybacking on the glycosomal PTS1-containing phosphoenolpyruvate carboxykinase (PEPCK) and identified the domains involved in the UGP/PEPCK interaction. Proximity ligation assays revealed that this interaction occurs in 3 to 10% of glycosomes, suggesting that these correspond to organelles competent for protein import. We also showed that UGP is essential for the growth of trypanosomes and that both the glycosomal and cytosolic metabolic pathways involving UGP are functional, since the lethality of the knockdown UGP mutant cell line (RNAiUGP, where RNAi indicates RNA interference) was rescued by expressing a recoded UGP (rUGP) in the organelle (RNAiUGP/EXPrUGP-GPDH, where GPDH is glycerol-3-phosphate dehydrogenase). Our conclusion was supported by targeted metabolomic analyses (ion chromatography–high-resolution mass spectrometry [IC-HRMS]) showing that UDP-glucose is no longer detectable in the RNAiUGP mutant, while it is still produced in cells expressing UGP exclusively in the cytosol (PEPCK null mutant) or glycosomes (RNAiUGP/EXPrUGP-GPDH). Trypanosomatids are the only known organisms to have selected functional peroxisomal (glycosomal) sugar nucleotide biosynthetic pathways in addition to the canonical cytosolic ones.
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12
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Bílý T, Sheikh S, Mallet A, Bastin P, Pérez-Morga D, Lukeš J, Hashimi H. Ultrastructural Changes of the Mitochondrion During the Life Cycle of Trypanosoma brucei. J Eukaryot Microbiol 2021; 68:e12846. [PMID: 33624359 DOI: 10.1111/jeu.12846] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/04/2021] [Accepted: 02/15/2021] [Indexed: 11/29/2022]
Abstract
The mitochondrion is crucial for ATP generation by oxidative phosphorylation, among other processes. Cristae are invaginations of the mitochondrial inner membrane that house nearly all the macromolecular complexes that perform oxidative phosphorylation. The unicellular parasite Trypanosoma brucei undergoes during its life cycle extensive remodeling of its single mitochondrion, which reflects major changes in its energy metabolism. While the bloodstream form (BSF) generates ATP exclusively by substrate-level phosphorylation and has a morphologically highly reduced mitochondrion, the insect-dwelling procyclic form (PCF) performs oxidative phosphorylation and has an expanded and reticulated organelle. Here, we have performed high-resolution 3D reconstruction of BSF and PCF mitochondria, with a particular focus on their cristae. By measuring the volumes and surface areas of these structures in complete or nearly complete cells, we have found that mitochondrial cristae are more prominent in BSF than previously thought and their biogenesis seems to be maintained during the cell cycle. Furthermore, PCF cristae exhibit a surprising range of volumes in situ, implying that each crista is acting as an independent bioenergetic unit. Cristae appear to be particularly enriched in the region of the organelle between the nucleus and kinetoplast, the mitochondrial genome, suggesting this part has distinctive properties.
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Affiliation(s)
- Tomáš Bílý
- Institute of Parasitology, Biology Center, Czech Academy of Sciences & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Shaghayegh Sheikh
- Institute of Parasitology, Biology Center, Czech Academy of Sciences & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Adeline Mallet
- Trypanosome Cell Biology Unit & INSERM U1201, Institut Pasteur, Paris, France.,Ultrastructural Bio Imaging Unit, C2RT, Institut Pasteur & Sorbonne Université école doctorale complexité du vivant, ED 515, Paris, France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit & INSERM U1201, Institut Pasteur, Paris, France
| | - David Pérez-Morga
- Laboratory of Molecular Parasitology, IBMM & Center for Microscopy and Molecular Imaging, Université Libre de Bruxelles, Brussels, Belgium
| | - Julius Lukeš
- Institute of Parasitology, Biology Center, Czech Academy of Sciences & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Hassan Hashimi
- Institute of Parasitology, Biology Center, Czech Academy of Sciences & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
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13
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Quiñones W, Acosta H, Gonçalves CS, Motta MCM, Gualdrón-López M, Michels PAM. Structure, Properties, and Function of Glycosomes in Trypanosoma cruzi. Front Cell Infect Microbiol 2020; 10:25. [PMID: 32083023 PMCID: PMC7005584 DOI: 10.3389/fcimb.2020.00025] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 01/15/2020] [Indexed: 12/29/2022] Open
Abstract
Glycosomes are peroxisome-related organelles that have been identified in kinetoplastids and diplonemids. The hallmark of glycosomes is their harboring of the majority of the glycolytic enzymes. Our biochemical studies and proteome analysis of Trypanosoma cruzi glycosomes have located, in addition to enzymes of the glycolytic pathway, enzymes of several other metabolic processes in the organelles. These analyses revealed many aspects in common with glycosomes from other trypanosomatids as well as features that seem specific for T. cruzi. Their enzyme content indicates that T. cruzi glycosomes are multifunctional organelles, involved in both several catabolic processes such as glycolysis and anabolic ones. Specifically discussed in this minireview are the cross-talk between glycosomal metabolism and metabolic processes occurring in other cell compartments, and the importance of metabolite translocation systems in the glycosomal membrane to enable the coordination between the spatially separated processes. Possible mechanisms for metabolite translocation across the membrane are suggested by proteins identified in the organelle's membrane-homologs of the ABC and MCF transporter families-and the presence of channels as inferred previously from the detection of channel-forming proteins in glycosomal membrane preparations from the related parasite T. brucei. Together, these data provide insight in the way in which different parts of T. cruzi metabolism, although uniquely distributed over different compartments, are integrated and regulated. Moreover, this information reveals opportunities for the development of drugs against Chagas disease caused by these parasites and for which currently no adequate treatment is available.
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Affiliation(s)
- Wilfredo Quiñones
- Laboratorio de Enzimología de Parásitos, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela
| | - Héctor Acosta
- Laboratorio de Enzimología de Parásitos, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela
| | - Camila Silva Gonçalves
- Laboratório de Ultraestrutura Celular Hertha Meyer, Centro de Ciências da Saúde, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maria Cristina M Motta
- Laboratório de Ultraestrutura Celular Hertha Meyer, Centro de Ciências da Saúde, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Melisa Gualdrón-López
- Instituto Salud Global, Hospital Clinic-Universitat de Barcelona, and Institute for Health Sciences Trias i Pujol, Barcelona, Spain
| | - Paul A M Michels
- Centre for Immunity, Infection and Evolution and Centre for Translational and Chemical Biology, The University of Edinburgh, Edinburgh, United Kingdom
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3D cellular reconstruction of cortical glia and parenchymal morphometric analysis from Serial Block-Face Electron Microscopy of juvenile rat. Prog Neurobiol 2019; 183:101696. [PMID: 31550514 DOI: 10.1016/j.pneurobio.2019.101696] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 09/12/2019] [Accepted: 09/17/2019] [Indexed: 01/04/2023]
Abstract
With the rapid evolution in the automation of serial electron microscopy in life sciences, the acquisition of terabyte-sized datasets is becoming increasingly common. High resolution serial block-face imaging (SBEM) of biological tissues offers the opportunity to segment and reconstruct nanoscale structures to reveal spatial features previously inaccessible with simple, single section, two-dimensional images. In particular, we focussed here on glial cells, whose reconstruction efforts in literature are still limited, compared to neurons. We imaged a 750,000 cubic micron volume of the somatosensory cortex from a juvenile P14 rat, with 20 nm accuracy. We recognized a total of 186 cells using their nuclei, and classified them as neuronal or glial based on features of the soma and the processes. We reconstructed for the first time 4 almost complete astrocytes and neurons, 4 complete microglia and 4 complete pericytes, including their intracellular mitochondria, 186 nuclei and 213 myelinated axons. We then performed quantitative analysis on the three-dimensional models. Out of the data that we generated, we observed that neurons have larger nuclei, which correlated with their lesser density, and that astrocytes and pericytes have a higher surface to volume ratio, compared to other cell types. All reconstructed morphologies represent an important resource for computational neuroscientists, as morphological quantitative information can be inferred, to tune simulations that take into account the spatial compartmentalization of the different cell types.
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15
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Abstract
Trypanosomes have complex life cycles within which there are both proliferative and differentiation cell divisions. The coordination of the cell cycle to achieve these different divisions is critical for the parasite to infect both host and vector. From studying the regulation of the proliferative cell cycle of the Trypanosoma brucei procyclic life cycle stage, three subcycles emerge that control the duplication and segregation of ( a) the nucleus, ( b) the kinetoplast, and ( c) a set of cytoskeletal structures. We discuss how the clear dependency relationships within these subcycles, and the potential for cross talk between them, are likely required for overall cell cycle coordination. Finally, we look at the implications this interdependence has for proliferative and differentiation divisions through the T. brucei life cycle and in related parasitic trypanosomatid species.
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Affiliation(s)
- Richard J. Wheeler
- Nuffield Department of Medicine, University of Oxford, Oxford OX1 3SY, United Kingdom
| | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Jack D. Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
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16
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Smith D, Starborg T. Serial block face scanning electron microscopy in cell biology: Applications and technology. Tissue Cell 2019; 57:111-122. [DOI: 10.1016/j.tice.2018.08.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/22/2018] [Accepted: 08/26/2018] [Indexed: 10/28/2022]
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17
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DiMaio J, Ruthel G, Cannon JJ, Malfara MF, Povelones ML. The single mitochondrion of the kinetoplastid parasite Crithidia fasciculata is a dynamic network. PLoS One 2018; 13:e0202711. [PMID: 30592713 PMCID: PMC6310254 DOI: 10.1371/journal.pone.0202711] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 12/11/2018] [Indexed: 11/18/2022] Open
Abstract
Mitochondria are central organelles in cellular metabolism. Their structure is highly dynamic, allowing them to adapt to different energy requirements, to be partitioned during cell division, and to maintain functionality. Mitochondrial dynamics, including membrane fusion and fission reactions, are well studied in yeast and mammals but it is not known if these processes are conserved throughout eukaryotic evolution. Kinetoplastid parasites are some of the earliest-diverging eukaryotes to retain a mitochondrion. Each cell has only a single mitochondrial organelle, making them an interesting model for the role of dynamics in controlling mitochondrial architecture. We have investigated the mitochondrial division cycle in the kinetoplastid Crithidia fasciculata. The majority of mitochondrial biogenesis occurs during the G1 phase of the cell cycle, and the mitochondrion is divided symmetrically in a process coincident with cytokinesis. Live cell imaging revealed that the mitochondrion is highly dynamic, with frequent changes in the topology of the branched network. These remodeling reactions include tubule fission, fusion, and sliding, as well as new tubule formation. We hypothesize that the function of this dynamic remodeling is to homogenize mitochondrial contents and to facilitate rapid transport of mitochondria-encoded gene products from the area containing the mitochondrial nucleoid to other parts of the organelle.
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Affiliation(s)
- John DiMaio
- Sciences Division, Brandywine Campus, The Pennsylvania State University, Media, Pennsylvania, United States of America
| | - Gordon Ruthel
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - Joshua J. Cannon
- Sciences Division, Brandywine Campus, The Pennsylvania State University, Media, Pennsylvania, United States of America
| | - Madeline F. Malfara
- Sciences Division, Brandywine Campus, The Pennsylvania State University, Media, Pennsylvania, United States of America
| | - Megan L. Povelones
- Sciences Division, Brandywine Campus, The Pennsylvania State University, Media, Pennsylvania, United States of America
- * E-mail:
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18
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Halliday C, Billington K, Wang Z, Madden R, Dean S, Sunter JD, Wheeler RJ. Cellular landmarks of Trypanosoma brucei and Leishmania mexicana. Mol Biochem Parasitol 2018; 230:24-36. [PMID: 30550896 PMCID: PMC6529878 DOI: 10.1016/j.molbiopara.2018.12.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 12/08/2018] [Accepted: 12/10/2018] [Indexed: 11/29/2022]
Abstract
Trypanosoma and Leishmania are single cell eukaryotic parasites. The cell organisation of these human pathogens is complex and highly structured. This describes an inventory of reliable reference markers for 32 cell structures. These light microscopy landmarks are a valuable resource for researchers.
The kinetoplastids Trypanosoma brucei and Leishmania mexicana are eukaryotes with a highly structured cellular organisation that is reproduced with great fidelity in each generation. The pattern of signal from a fluorescently tagged protein can define the specific structure/organelle that this protein localises to, and can be extremely informative in phenotype analysis in experimental perturbations, life cycle tracking, post-genomic assays and functional analysis of organelles. Using the vast coverage of protein subcellular localisations provided by the TrypTag project, an ongoing project to determine the localisation of every protein encoded in the T. brucei genome, we have generated an inventory of reliable reference organelle markers for both parasites that combines epifluorescence images with a detailed description of the key features of each localisation. We believe this will be a useful comparative resource that will enable researchers to quickly and accurately pinpoint the localisation of their proteins of interest and will provide cellular markers for many types of cell biology studies. We see this as another important step in the post-genomic era analyses of these parasites, in which ever expanding datasets generate numerous candidates to analyse. Adoption of these reference proteins by the community is likely to enhance research studies and enable better comparison of data.
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Affiliation(s)
- Clare Halliday
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK; Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Karen Billington
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Ziyin Wang
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Ross Madden
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Samuel Dean
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
| | - Jack Daniel Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK.
| | - Richard John Wheeler
- The Peter Medawar Building for Pathogen Research, University of Oxford, South Parks Road, Oxford, OX1 3SY, UK.
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Bertiaux E, Mallet A, Fort C, Blisnick T, Bonnefoy S, Jung J, Lemos M, Marco S, Vaughan S, Trépout S, Tinevez JY, Bastin P. Bidirectional intraflagellar transport is restricted to two sets of microtubule doublets in the trypanosome flagellum. J Cell Biol 2018; 217:4284-4297. [PMID: 30275108 PMCID: PMC6279389 DOI: 10.1083/jcb.201805030] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 08/06/2018] [Accepted: 09/21/2018] [Indexed: 12/22/2022] Open
Abstract
Intraflagellar transport (IFT) is the movement of large protein complexes responsible for the construction of cilia and flagella. Using a combination of three-dimensional electron microscopy and high-resolution live imaging, Bertiaux et al. show that IFT takes place on only four microtubule doublets out of the nine available in the trypanosome flagellum. Intraflagellar transport (IFT) is the rapid bidirectional movement of large protein complexes driven by kinesin and dynein motors along microtubule doublets of cilia and flagella. In this study, we used a combination of high-resolution electron and light microscopy to investigate how and where these IFT trains move within the flagellum of the protist Trypanosoma brucei. Focused ion beam scanning electron microscopy (FIB-SEM) analysis of trypanosomes showed that trains are found almost exclusively along two sets of doublets (3–4 and 7–8) and distribute in two categories according to their length. High-resolution live imaging of cells expressing mNeonGreen::IFT81 or GFP::IFT52 revealed for the first time IFT trafficking on two parallel lines within the flagellum. Anterograde and retrograde IFT occurs on each of these lines. At the distal end, a large individual anterograde IFT train is converted in several smaller retrograde trains in the space of 3–4 s while remaining on the same side of the axoneme.
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Affiliation(s)
- Eloïse Bertiaux
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France.,Université Pierre et Marie Curie Paris 6, Cellule Pasteur, Paris, France
| | - Adeline Mallet
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France.,Université Pierre et Marie Curie Paris 6, Cellule Pasteur, Paris, France.,UtechS Ultrastructural Bioimaging (Ultrapole), Institut Pasteur, Paris, France
| | - Cécile Fort
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France.,Université Pierre et Marie Curie Paris 6, Cellule Pasteur, Paris, France
| | - Thierry Blisnick
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France
| | - Serge Bonnefoy
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France
| | - Jamin Jung
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France
| | - Moara Lemos
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France
| | - Sergio Marco
- Université Paris Sud, Université Paris-Saclay, Centre National de la Recherche Scientifique, UMR 9187, Orsay, France.,Institut Curie, Paris Sciences et Lettres Research University, INSERM U1196, Orsay, France
| | - Sue Vaughan
- Department of Biological and Medical Sciences, Faculty of Health and Life Science, Oxford Brookes University, Oxford, UK
| | - Sylvain Trépout
- Université Paris Sud, Université Paris-Saclay, Centre National de la Recherche Scientifique, UMR 9187, Orsay, France.,Institut Curie, Paris Sciences et Lettres Research University, INSERM U1196, Orsay, France
| | - Jean-Yves Tinevez
- UtechS Photonic Bioimaging (Imagopole), Institut Pasteur, Paris, France.,Image Analysis Hub, Institut Pasteur, Paris, France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, Paris, France
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20
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Alcantara CDL, de Souza W, da Cunha E Silva NL. Tridimensional Electron Microscopy Analysis of the Early Endosomes and Endocytic Traffic in Trypanosoma cruzi Epimastigotes. Protist 2018; 169:887-910. [PMID: 30447618 DOI: 10.1016/j.protis.2018.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 08/25/2018] [Accepted: 09/24/2018] [Indexed: 02/04/2023]
Abstract
Trypanosoma cruzi epimastigotes internalize macromolecules avidly by endocytosis. Previously, we identified a tubule-vesicular network likely to correspond to the early-endosomes. However, a detailed ultrastructural characterization of these endosomes was missing. Here, we combined endocytosis assays with ultrastructural data from high-resolution electron microscopy to produce a 3D analysis of epimastigote endosomes and their interactions with endocytic organelles. We showed that endocytic cargo was found in carrier vesicles budding from the cytopharynx. These vesicles appeared to fuse with a tubule-vesicular network of early endosomes identified by ultrastructural features including the presence of intermembrane invaginations and coated membrane sections. Within the posterior region of the cell, endosomes localized preferentially on the side nearest to the cytopharynx microtubules. At 4°C, cargo accumulated at a shortened cytopharynx, and subsequent temperature shift to 12°C led to slow cargo delivery to endosomes and, later, to reservosomes. Bridges between reservosomes and endosomes resemble heterotypic fusion. Reservosomes are excluded from the posterior end of the cell, with no preferential cargo delivery to reservosomes closer to the nucleus. Our 3D analysis indicates that epimastigotes accomplish high-speed endocytic traffic by cargo transfer to a bona fide early-endosome and then directly from endosomes to reservosomes, via multiple and simultaneous heterotypic fusion events.
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Affiliation(s)
- Carolina de Lima Alcantara
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil; Núcleo de Biologia Estrutural e Bioimagens (CENABIO) - Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Biomagens (INBEB), Rio de Janeiro 21941-902, RJ, Brazil.
| | - Wanderley de Souza
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil; Núcleo de Biologia Estrutural e Bioimagens (CENABIO) - Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Biomagens (INBEB), Rio de Janeiro 21941-902, RJ, Brazil
| | - Narcisa L da Cunha E Silva
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil; Núcleo de Biologia Estrutural e Bioimagens (CENABIO) - Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Biomagens (INBEB), Rio de Janeiro 21941-902, RJ, Brazil
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21
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Abstract
Trypanosoma brucei is a highly invasive pathogen capable of penetrating deeply into host tissues. To understand how flagellar motility facilitates cell penetration, we used cryo-electron tomography (cryo-ET) to visualize two genetically anucleate mutants with different flagellar motility behaviors. We found that the T. brucei cell body is highly deformable as defined by changes in cytoskeletal twist and spacing, in response to flagellar beating and environmental conditions. Based on the cryo-ET models, we proposed a mechanism of how flagellum motility is coupled to cell shape changes, which may facilitate penetration through size-limiting barriers. In the unicellular parasite Trypanosoma brucei, the causative agent of human African sleeping sickness, complex swimming behavior is driven by a flagellum laterally attached to the long and slender cell body. Using microfluidic assays, we demonstrated that T. brucei can penetrate through an orifice smaller than its maximum diameter. Efficient motility and penetration depend on active flagellar beating. To understand how active beating of the flagellum affects the cell body, we genetically engineered T. brucei to produce anucleate cytoplasts (zoids and minis) with different flagellar attachment configurations and different swimming behaviors. We used cryo-electron tomography (cryo-ET) to visualize zoids and minis vitrified in different motility states. We showed that flagellar wave patterns reflective of their motility states are coupled to cytoskeleton deformation. Based on these observations, we propose a mechanism for how flagellum beating can deform the cell body via a flexible connection between the flagellar axoneme and the cell body. This mechanism may be critical for T. brucei to disseminate in its host through size-limiting barriers.
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22
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New advances in scanning microscopy and its application to study parasitic protozoa. Exp Parasitol 2018; 190:10-33. [PMID: 29702111 DOI: 10.1016/j.exppara.2018.04.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 04/10/2018] [Accepted: 04/23/2018] [Indexed: 12/31/2022]
Abstract
Scanning electron microscopy has been used to observe and study parasitic protozoa for at least 40 years. However, field emission electron sources, as well as improvements in lenses and detectors, brought the resolution power of scanning electron microscopes (SEM) to a new level. Parallel to the refinement of instruments, protocols for preservation of the ultrastructure, immunolabeling, exposure of cytoskeleton and inner structures of parasites and host cells were developed. This review is focused on protozoan parasites of medical and veterinary relevance, e.g., Toxoplasma gondii, Tritrichomonas foetus, Giardia intestinalis, and Trypanosoma cruzi, compilating the main achievements in describing the fine ultrastructure of their surface, cytoskeleton and interaction with host cells. Two new resources, namely, Helium Ion Microscopy (HIM) and Slice and View, using either Focused Ion Beam (FIB) abrasion or Microtome Serial Sectioning (MSS) within the microscope chamber, combined to backscattered electron imaging of fixed (chemically or by quick freezing followed by freeze substitution and resin embedded samples is bringing an exponential amount of valuable information. In HIM there is no need of conductive coating and the depth of field is much higher than in any field emission SEM. As for FIB- and MSS-SEM, high resolution 3-D models of areas and volumes larger than any other technique allows can be obtained. The main results achieved with all these technological tools and some protocols for sample preparation are included in this review. In addition, we included some results obtained with environmental/low vacuum scanning microscopy and cryo-scanning electron microscopy, both promising, but not yet largely employed SEM modalities.
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23
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Ooi CP, Smith TK, Gluenz E, Wand NV, Vaughan S, Rudenko G. Blocking variant surface glycoprotein synthesis alters endoplasmic reticulum exit sites/Golgi homeostasis in Trypanosoma brucei. Traffic 2018; 19:391-405. [PMID: 29533496 PMCID: PMC6001540 DOI: 10.1111/tra.12561] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 03/08/2018] [Accepted: 03/08/2018] [Indexed: 12/31/2022]
Abstract
The predominant secretory cargo of bloodstream form Trypanosoma brucei is variant surface glycoprotein (VSG), comprising ~10% total protein and forming a dense protective layer. Blocking VSG translation using Morpholino oligonucleotides triggered a precise pre‐cytokinesis arrest. We investigated the effect of blocking VSG synthesis on the secretory pathway. The number of Golgi decreased, particularly in post‐mitotic cells, from 3.5 ± 0.6 to 2.0 ± 0.04 per cell. Similarly, the number of endoplasmic reticulum exit sites (ERES) in post‐mitotic cells dropped from 3.9 ± 0.6 to 2.7 ± 0.1 eight hours after blocking VSG synthesis. The secretory pathway was still functional in these stalled cells, as monitored using Cathepsin L. Rates of phospholipid and glycosylphosphatidylinositol‐anchor biosynthesis remained relatively unaffected, except for the level of sphingomyelin which increased. However, both endoplasmic reticulum and Golgi morphology became distorted, with the Golgi cisternae becoming significantly dilated, particularly at the trans‐face. Membrane accumulation in these structures is possibly caused by reduced budding of nascent vesicles due to the drastic reduction in the total amount of secretory cargo, that is, VSG. These data argue that the total flux of secretory cargo impacts upon the biogenesis and maintenance of secretory structures and organelles in T. brucei, including the ERES and Golgi.
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Affiliation(s)
- Cher-Pheng Ooi
- Department of Life Sciences, Imperial College London, London, UK
| | - Terry K Smith
- BSRC, School of Biology, University of St. Andrews, St. Andrews, UK
| | - Eva Gluenz
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | | | - Sue Vaughan
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Gloria Rudenko
- Department of Life Sciences, Imperial College London, London, UK
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24
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Naguleswaran A, Doiron N, Roditi I. RNA-Seq analysis validates the use of culture-derived Trypanosoma brucei and provides new markers for mammalian and insect life-cycle stages. BMC Genomics 2018; 19:227. [PMID: 29606092 PMCID: PMC5879877 DOI: 10.1186/s12864-018-4600-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 03/13/2018] [Indexed: 01/03/2023] Open
Abstract
Background Trypanosoma brucei brucei, the parasite causing Nagana in domestic animals, is closely related to the parasites causing sleeping sickness, but does not infect humans. In addition to its importance as a pathogen, the relative ease of genetic manipulation and an innate capacity for RNAi extend its use as a model organism in cell and infection biology. During its development in its mammalian and insect (tsetse fly) hosts, T. b. brucei passes through several different life-cycle stages. There are currently four life-cycle stages that can be cultured: slender forms and stumpy forms, which are equivalent to forms found in the mammal, and early and late procyclic forms, which are equivalent to forms in the tsetse midgut. Early procyclic forms show coordinated group movement (social motility) on semi-solid surfaces, whereas late procyclic forms do not. Results RNA-Seq was performed on biological replicates of each life-cycle stage. These constitute the first datasets for culture-derived slender and stumpy bloodstream forms and early and late procyclic forms. Expression profiles confirmed that genes known to be stage-regulated in the animal and insect hosts were also regulated in culture. Sequence reads of 100–125 bases provided sufficient precision to uncover differential expression of closely related genes. More than 100 transcripts showed peak expression in stumpy forms, including adenylate cyclases and several components of inositol metabolism. Early and late procyclic forms showed differential expression of 73 transcripts, a number of which encoded proteins that were previously shown to be stage-regulated. Moreover, two adenylate cyclases previously shown to reduce social motility are up-regulated in late procyclic forms. Conclusions This study validates the use of cultured bloodstream forms as alternatives to animal-derived parasites and yields new markers for all four stages. In addition to underpinning recent findings that early and late procyclic forms are distinct life-cycle stages, it could provide insights into the reasons for their different biological properties. Electronic supplementary material The online version of this article (10.1186/s12864-018-4600-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Nicholas Doiron
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012, Bern, Switzerland
| | - Isabel Roditi
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012, Bern, Switzerland.
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25
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Benz C, Dondelinger F, McKean PG, Urbaniak MD. Cell cycle synchronisation of Trypanosoma brucei by centrifugal counter-flow elutriation reveals the timing of nuclear and kinetoplast DNA replication. Sci Rep 2017; 7:17599. [PMID: 29242601 PMCID: PMC5730572 DOI: 10.1038/s41598-017-17779-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/29/2017] [Indexed: 01/06/2023] Open
Abstract
We report an optimised centrifugal counter-flow elutriation protocol for the rapid and direct isolation of G1 cell cycle synchronised populations of both the procyclic and bloodstream form stages of Trypanosoma brucei that yields viable and proliferative cells. The high quality of the synchronisation achieved can be judged by the uniform DNA content, narrow size distribution, synchronous division, and the maintenance of synchronicity into subsequent cell cycles. We show that early-eluting fractions represent different G1 subpopulations that progress through the cell cycle with distinct temporal profiles post-elutriation, as exemplified by the observation of the maturation of a second flagellar basal body in late G1 phase, DNA replication in S phase, and dimethylation of histone H3 in mitosis/cytokinesis. We use our temporal observations to construct a revised model of the relative timing and duration of the nuclear and kinetoplast cell cycle that differs from the current model.
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Affiliation(s)
- Corinna Benz
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK
| | - Frank Dondelinger
- Lancaster Medical School, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK
| | - Paul G McKean
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK
| | - Michael D Urbaniak
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK.
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Albisetti A, Florimond C, Landrein N, Vidilaseris K, Eggenspieler M, Lesigang J, Dong G, Robinson DR, Bonhivers M. Interaction between the flagellar pocket collar and the hook complex via a novel microtubule-binding protein in Trypanosoma brucei. PLoS Pathog 2017; 13:e1006710. [PMID: 29091964 PMCID: PMC5683654 DOI: 10.1371/journal.ppat.1006710] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 11/13/2017] [Accepted: 10/24/2017] [Indexed: 12/16/2022] Open
Abstract
Trypanosoma brucei belongs to a group of unicellular, flagellated parasites that are responsible for human African trypanosomiasis. An essential aspect of parasite pathogenicity is cytoskeleton remodelling, which occurs during the life cycle of the parasite and is accompanied by major changes in morphology and organelle positioning. The flagellum originates from the basal bodies and exits the cell body through the flagellar pocket (FP) but remains attached to the cell body via the flagellum attachment zone (FAZ). The FP is an invagination of the pellicular membrane and is the sole site for endo- and exocytosis. The FAZ is a large complex of cytoskeletal proteins, plus an intracellular set of four specialised microtubules (MtQ) that elongate from the basal bodies to the anterior end of the cell. At the distal end of the FP, an essential, intracellular, cytoskeletal structure called the flagellar pocket collar (FPC) circumvents the flagellum. Overlapping the FPC is the hook complex (HC) (a sub-structure of the previously named bilobe) that is also essential and is thought to be involved in protein FP entry. BILBO1 is the only functionally characterised FPC protein and is necessary for FPC and FP biogenesis. Here, we used a combination of in vitro and in vivo approaches to identify and characterize a new BILBO1 partner protein-FPC4. We demonstrate that FPC4 localises to the FPC, the HC, and possibly to a proximal portion of the MtQ. We found that the C-terminal domain of FPC4 interacts with the BILBO1 N-terminal domain, and we identified the key amino acids required for this interaction. Interestingly, the FPC4 N-terminal domain was found to bind microtubules. Over-expression studies highlight the role of FPC4 in its association with the FPC, HC and FPC segregation. Our data suggest a tripartite association between the FPC, the HC and the MtQ.
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Affiliation(s)
- Anna Albisetti
- University of Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Célia Florimond
- University of Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Nicolas Landrein
- University of Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Keni Vidilaseris
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna, Austria
| | - Marie Eggenspieler
- University of Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Johannes Lesigang
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna, Austria
| | - Gang Dong
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna, Austria
| | - Derrick Roy Robinson
- University of Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Mélanie Bonhivers
- University of Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
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Cooper C, Thompson RCA, Botero A, Kristancic A, Peacock C, Kirilak Y, Clode PL. A comparative molecular and 3-dimensional structural investigation into cross-continental and novel avian Trypanosoma spp. in Australia. Parasit Vectors 2017; 10:234. [PMID: 28499405 PMCID: PMC5427604 DOI: 10.1186/s13071-017-2173-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 05/03/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Molecular and structural information on avian Trypanosoma spp. throughout Australia is limited despite their intrinsic value in understanding trypanosomatid evolution, diversity, and structural biology. In Western Australia tissue samples (n = 429) extracted from 93 birds in 25 bird species were screened using generic PCR primers to investigate the diversity of Trypanosoma spp. To investigate avian trypanosome structural biology the first 3-dimensional ultrastructural models of a Trypanosoma spp. (Trypanosoma sp. AAT) isolated from a bird (currawong, Strepera spp.) were generated using focussed ion beam milling combined with scanning electron microscopy (FIB-SEM). RESULTS Here, we confirm four intercontinental species of avian trypanosomes in native Australian birds, and identify a new avian Trypanosoma. Trypanosome infection was identified in 18 birds from 13 different bird species (19%). A single new genotype was isolated and found to be closely related to T. culicavium (Trypanosoma sp. CC2016 B002). Other Trypanosoma spp. identified include T. avium, T. culicavium, T. thomasbancrofti, Trypanosoma sp. TL.AQ.22, Trypanosoma sp. AAT, and an uncharacterised Trypanosoma sp. (group C-III sensu Zidková et al. (Infect Genet Evol 12:102-112, 2012)), all previously identified in Australia or other continents. Serially-sectioning Trypanosoma sp. AAT epimastigotes using FIB-SEM revealed the disc-shaped kinetoplast pocket attached perpendicular to the branching mitochondrion. Additionally, the universal minicircle sequence within the kinetoplast DNA and the associated binding protein were determined in Trypanosoma sp. AAT. CONCLUSIONS These results indicate that bird trypanosomes are relatively conserved across continents, while being locally diverse, which supports the hypothesis that bird trypanosomes exist as fewer species than described in the literature. Evidence exists that avian Trypanosoma spp. are infecting mammals and could be transmitted by haemadipsid leeches. Trypanosoma sp. AAT is most likely a separate species currently found only in Australia and the first 3-dimentional ultrastructural analysis of an avian trypanosome provides interesting information on their morphology and organelle arrangement.
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Affiliation(s)
- Crystal Cooper
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009 Australia
| | - R. C. Andrew Thompson
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150 Australia
| | - Adriana Botero
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150 Australia
| | - Amanda Kristancic
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150 Australia
| | - Christopher Peacock
- Marshall Centre, School of Pathology and Laboratory and Medical Sciences, University of Western Australia, Crawley, WA 6009 Australia
- Telethon Kids Institute, 100 Roberts Rd, Subiaco, WA 6008 Australia
| | - Yaowanuj Kirilak
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009 Australia
| | - Peta L. Clode
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009 Australia
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Ferguson S, Steyer AM, Mayhew TM, Schwab Y, Lucocq JM. Quantifying Golgi structure using EM: combining volume-SEM and stereology for higher throughput. Histochem Cell Biol 2017; 147:653-669. [PMID: 28429122 PMCID: PMC5429891 DOI: 10.1007/s00418-017-1564-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2017] [Indexed: 12/28/2022]
Abstract
Investigating organelles such as the Golgi complex depends increasingly on high-throughput quantitative morphological analyses from multiple experimental or genetic conditions. Light microscopy (LM) has been an effective tool for screening but fails to reveal fine details of Golgi structures such as vesicles, tubules and cisternae. Electron microscopy (EM) has sufficient resolution but traditional transmission EM (TEM) methods are slow and inefficient. Newer volume scanning EM (volume-SEM) methods now have the potential to speed up 3D analysis by automated sectioning and imaging. However, they produce large arrays of sections and/or images, which require labour-intensive 3D reconstruction for quantitation on limited cell numbers. Here, we show that the information storage, digital waste and workload involved in using volume-SEM can be reduced substantially using sampling-based stereology. Using the Golgi as an example, we describe how Golgi populations can be sensed quantitatively using single random slices and how accurate quantitative structural data on Golgi organelles of individual cells can be obtained using only 5–10 sections/images taken from a volume-SEM series (thereby sensing population parameters and cell–cell variability). The approach will be useful in techniques such as correlative LM and EM (CLEM) where small samples of cells are treated and where there may be variable responses. For Golgi study, we outline a series of stereological estimators that are suited to these analyses and suggest workflows, which have the potential to enhance the speed and relevance of data acquisition in volume-SEM.
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Affiliation(s)
- Sophie Ferguson
- Structural Cell Biology Group, School of Medicine, University of St Andrews, North Haugh, Fife, KY16 9TF, Scotland, UK
| | - Anna M Steyer
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - Terry M Mayhew
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Yannick Schwab
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - John Milton Lucocq
- Structural Cell Biology Group, School of Medicine, University of St Andrews, North Haugh, Fife, KY16 9TF, Scotland, UK.
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Hughes L, Borrett S, Towers K, Starborg T, Vaughan S. Patterns of organelle ontogeny through a cell cycle revealed by whole-cell reconstructions using 3D electron microscopy. Development 2017. [DOI: 10.1242/dev.150045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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