1
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The Role of Mitophagy in Various Neurological Diseases as a Therapeutic Approach. Cell Mol Neurobiol 2022:10.1007/s10571-022-01302-8. [DOI: 10.1007/s10571-022-01302-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/24/2022] [Indexed: 11/05/2022]
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2
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Bury AG, Vincent AE, Turnbull DM, Actis P, Hudson G. Mitochondrial isolation: when size matters. Wellcome Open Res 2021; 5:226. [PMID: 33718619 PMCID: PMC7931255 DOI: 10.12688/wellcomeopenres.16300.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2020] [Indexed: 12/24/2022] Open
Abstract
Mitochondrial vitality is critical to cellular function, with mitochondrial dysfunction linked to a growing number of human diseases. Tissue and cellular heterogeneity, in terms of genetics, dynamics and function means that increasingly mitochondrial research is conducted at the single cell level. Whilst there are several technologies that are currently available for single-cell analysis, each with their advantages, they cannot be easily adapted to study mitochondria with subcellular resolution. Here we review the current techniques and strategies for mitochondrial isolation, critically discussing each technology's limitations for future mitochondrial research. Finally, we highlight and discuss the recent breakthroughs in sub-cellular isolation techniques, with a particular focus on nanotechnologies that enable the isolation of mitochondria from subcellular compartments. This allows isolation of mitochondria with unprecedented spatial precision with minimal disruption to mitochondria and their immediate cellular environment.
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Affiliation(s)
- Alexander G Bury
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK.,Biosciences Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK.,Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Amy E Vincent
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK.,Translational and Clinical Research Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK.,Translational and Clinical Research Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
| | - Paolo Actis
- Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Gavin Hudson
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK.,Biosciences Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
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3
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Bury AG, Vincent AE, Turnbull DM, Actis P, Hudson G. Mitochondrial isolation: when size matters. Wellcome Open Res 2020; 5:226. [PMID: 33718619 PMCID: PMC7931255 DOI: 10.12688/wellcomeopenres.16300.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2020] [Indexed: 01/31/2024] Open
Abstract
Mitochondrial vitality is critical to cellular function, with mitochondrial dysfunction linked to a growing number of human diseases. Tissue and cellular heterogeneity, in terms of genetics, dynamics and function means that increasingly mitochondrial research is conducted at the single cell level. Whilst there are several technologies that are currently available for single-cell analysis, each with their advantages, they cannot be easily adapted to study mitochondria with subcellular resolution. Here we review the current techniques and strategies for mitochondrial isolation, critically discussing each technology's limitations for future mitochondrial research. Finally, we highlight and discuss the recent breakthroughs in sub-cellular isolation techniques, with a particular focus on nanotechnologies that enable the isolation of mitochondria from subcellular compartments. This allows isolation of mitochondria with unprecedented spatial precision with minimal disruption to mitochondria and their immediate cellular environment.
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Affiliation(s)
- Alexander G. Bury
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
- Biosciences Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
- Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Amy E. Vincent
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
- Translational and Clinical Research Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
| | - Doug M. Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
- Translational and Clinical Research Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
| | - Paolo Actis
- Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Gavin Hudson
- Wellcome Trust Centre for Mitochondrial Research, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
- Biosciences Institute, Medical School, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
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4
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Evolving mtDNA populations within cells. Biochem Soc Trans 2020; 47:1367-1382. [PMID: 31484687 PMCID: PMC6824680 DOI: 10.1042/bst20190238] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/06/2019] [Accepted: 08/08/2019] [Indexed: 12/14/2022]
Abstract
Mitochondrial DNA (mtDNA) encodes vital respiratory machinery. Populations of mtDNA molecules exist in most eukaryotic cells, subject to replication, degradation, mutation, and other population processes. These processes affect the genetic makeup of cellular mtDNA populations, changing cell-to-cell distributions, means, and variances of mutant mtDNA load over time. As mtDNA mutant load has nonlinear effects on cell functionality, and cell functionality has nonlinear effects on tissue performance, these statistics of cellular mtDNA populations play vital roles in health, disease, and inheritance. This mini review will describe some of the better-known ways in which these populations change over time in different organisms, highlighting the importance of quantitatively understanding both mutant load mean and variance. Due to length constraints, we cannot attempt to be comprehensive but hope to provide useful links to some of the many excellent studies on these topics.
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5
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Morris J, Na YJ, Zhu H, Lee JH, Giang H, Ulyanova AV, Baltuch GH, Brem S, Chen HI, Kung DK, Lucas TH, O'Rourke DM, Wolf JA, Grady MS, Sul JY, Kim J, Eberwine J. Pervasive within-Mitochondrion Single-Nucleotide Variant Heteroplasmy as Revealed by Single-Mitochondrion Sequencing. Cell Rep 2018; 21:2706-2713. [PMID: 29212019 DOI: 10.1016/j.celrep.2017.11.031] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/05/2017] [Accepted: 11/08/2017] [Indexed: 11/18/2022] Open
Abstract
A number of mitochondrial diseases arise from single-nucleotide variant (SNV) accumulation in multiple mitochondria. Here, we present a method for identification of variants present at the single-mitochondrion level in individual mouse and human neuronal cells, allowing for extremely high-resolution study of mitochondrial mutation dynamics. We identified extensive heteroplasmy between individual mitochondrion, along with three high-confidence variants in mouse and one in human that were present in multiple mitochondria across cells. The pattern of variation revealed by single-mitochondrion data shows surprisingly pervasive levels of heteroplasmy in inbred mice. Distribution of SNV loci suggests inheritance of variants across generations, resulting in Poisson jackpot lines with large SNV load. Comparison of human and mouse variants suggests that the two species might employ distinct modes of somatic segregation. Single-mitochondrion resolution revealed mitochondria mutational dynamics that we hypothesize to affect risk probabilities for mutations reaching disease thresholds.
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Affiliation(s)
- Jacqueline Morris
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Young-Ji Na
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hua Zhu
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jae-Hee Lee
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hoa Giang
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alexandra V Ulyanova
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Gordon H Baltuch
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Steven Brem
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - H Isaac Chen
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David K Kung
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Timothy H Lucas
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Donald M O'Rourke
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - John A Wolf
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - M Sean Grady
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jai-Yoon Sul
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Junhyong Kim
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - James Eberwine
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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6
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Johnston IG, Burgstaller JP, Havlicek V, Kolbe T, Rülicke T, Brem G, Poulton J, Jones NS. Stochastic modelling, Bayesian inference, and new in vivo measurements elucidate the debated mtDNA bottleneck mechanism. eLife 2015; 4:e07464. [PMID: 26035426 PMCID: PMC4486817 DOI: 10.7554/elife.07464] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/29/2015] [Indexed: 12/14/2022] Open
Abstract
Dangerous damage to mitochondrial DNA (mtDNA) can be ameliorated during mammalian development through a highly debated mechanism called the mtDNA bottleneck. Uncertainty surrounding this process limits our ability to address inherited mtDNA diseases. We produce a new, physically motivated, generalisable theoretical model for mtDNA populations during development, allowing the first statistical comparison of proposed bottleneck mechanisms. Using approximate Bayesian computation and mouse data, we find most statistical support for a combination of binomial partitioning of mtDNAs at cell divisions and random mtDNA turnover, meaning that the debated exact magnitude of mtDNA copy number depletion is flexible. New experimental measurements from a wild-derived mtDNA pairing in mice confirm the theoretical predictions of this model. We analytically solve a mathematical description of this mechanism, computing probabilities of mtDNA disease onset, efficacy of clinical sampling strategies, and effects of potential dynamic interventions, thus developing a quantitative and experimentally-supported stochastic theory of the bottleneck. DOI:http://dx.doi.org/10.7554/eLife.07464.001 Mitochondria are structures that provide vital sources of energy in our cells. DNA contained within mitochondria encodes important mitochondrial machinery, and most human cells contain hundreds or thousands of mitochondrial DNA molecules in addition to the DNA that is stored in the nucleus. Mitochondrial DNA is inherited from mothers via the egg, and the details of this inheritance are poorly understood. This question is important because inherited mistakes in mitochondrial DNA can have detrimental consequences on health, with links to fatal diseases and many other conditions. An unfertilised egg cell contains many copies of mitochondrial DNA molecules; some may have mutations and some may not. After fertilisation, the egg divides, the number of cells in the developing embryo increases, and the number of mitochondrial DNA molecules per cell changes. If the original egg cell contained defective mitochondrial DNA, some of these new cells end up containing more defective copies than others, leading to cell-to-cell differences in the developing embryo. This potentially allows cells with the greatest number of defective mitochondria to be eliminated. The increase in this cell-to-cell variability is called ‘bottlenecking’, and its mechanism remains highly debated. Johnston et al. have now used tools from maths, statistics and new experiments to address this debate, in the light of several studies that measured the mitochondrial DNA content in developing mice. This approach allowed a new theoretical model of mitochondrial DNA during the growth of an organism to be produced, which encompasses a wide range of existing theories and allows them to be compared. This model starts from the viewpoint that the hundreds or thousands of mitochondrial DNA molecules in a cell can be thought of as a population undergoing random ‘birth’ and ‘death’, and it allows the first statistical comparison of the many proposed bottleneck mechanisms. Johnston et al. find support for two ways that cells segregate mitochondria as they multiply, and show that the decrease in the number of mitochondrial DNA molecules during bottlenecking is flexible. This reconciles a debate amongst previous studies. These findings are confirmed using new experimental data from mice, which are genetically distinct from existing studies, illustrating the generality of the model's findings. Furthermore, an analytic mathematical description that describes in detail how bottlenecking might work is produced. Finally, Johnston et al. provide examples using this new theoretical model to suggest therapeutic strategies for diseases caused by mitochondrial DNA mutations. Future work will need to test these suggestions, and link mathematical understanding of mitochondria with healthcare data. DOI:http://dx.doi.org/10.7554/eLife.07464.002
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Affiliation(s)
- Iain G Johnston
- Department of Mathematics, Imperial College London, London, United Kingdom
| | - Joerg P Burgstaller
- Biotechnology in Animal Production, Department for Agrobiotechnology, IFA Tulln, IFA Tulln, Tulln, Austria
| | - Vitezslav Havlicek
- Reproduction Centre Wieselburg, Department for Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Thomas Kolbe
- Biomodels Austria, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Thomas Rülicke
- Institute of Laboratory Animal Science, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Gottfried Brem
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Jo Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, United Kingdom
| | - Nick S Jones
- Department of Mathematics, Imperial College London, London, United Kingdom
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7
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Christie JR, Schaerf TM, Beekman M. Selection against heteroplasmy explains the evolution of uniparental inheritance of mitochondria. PLoS Genet 2015; 11:e1005112. [PMID: 25880558 PMCID: PMC4400020 DOI: 10.1371/journal.pgen.1005112] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/28/2015] [Indexed: 12/03/2022] Open
Abstract
Why are mitochondria almost always inherited from one parent during sexual reproduction? Current explanations for this evolutionary mystery include conflict avoidance between the nuclear and mitochondrial genomes, clearing of deleterious mutations, and optimization of mitochondrial-nuclear coadaptation. Mathematical models, however, fail to show that uniparental inheritance can replace biparental inheritance under any existing hypothesis. Recent empirical evidence indicates that mixing two different but normal mitochondrial haplotypes within a cell (heteroplasmy) can cause cell and organism dysfunction. Using a mathematical model, we test if selection against heteroplasmy can lead to the evolution of uniparental inheritance. When we assume selection against heteroplasmy and mutations are neither advantageous nor deleterious (neutral mutations), uniparental inheritance replaces biparental inheritance for all tested parameter values. When heteroplasmy involves mutations that are advantageous or deleterious (non-neutral mutations), uniparental inheritance can still replace biparental inheritance. We show that uniparental inheritance can evolve with or without pre-existing mating types. Finally, we show that selection against heteroplasmy can explain why some organisms deviate from strict uniparental inheritance. Thus, we suggest that selection against heteroplasmy explains the evolution of uniparental inheritance. Mitochondria contain genes that encode the machinery needed to power cells. Unlike the nuclear genome, the mitochondrial genome is typically inherited from one parent only (uniparental inheritance). The most common explanation for uniparental inheritance is the genomic conflict theory, which states that uniparental inheritance evolved to prevent the spread of ‘selfish’ mitochondria that replicate quickly but produce energy inefficiently. Current explanations have a major problem: when using realistic parameters, mathematical models cannot show that uniparental inheritance can replace biparental inheritance. Clearly, we need a new explanation that fits with standard population-genetic theory. Recent evidence suggests cells may incur a cost when they carry multiple types of mitochondria. Here we show mathematically that uniparental inheritance could have evolved to avoid the costs of maintaining multiple mitochondrial lineages within a cell. Our results explain the long-standing evolutionary mystery of uniparental inheritance and provide insight into the evolution of mating types and binary sexes. Selection against heteroplasmy also has implications for the evolution of the mitochondrial genome because new mitochondrial haplotypes always lead to heteroplasmy before becoming fixed in the population. Thus, selection against heteroplasmy may explain why mtDNA coding-genes have slower substitution rates than analogous genes within the nucleus.
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Affiliation(s)
- Joshua R. Christie
- School of Biological Sciences, The University of Sydney, Sydney, Australia
- Centre for Mathematical Biology, The University of Sydney, Sydney, Australia
- * E-mail:
| | - Timothy M. Schaerf
- School of Biological Sciences, The University of Sydney, Sydney, Australia
- Centre for Mathematical Biology, The University of Sydney, Sydney, Australia
| | - Madeleine Beekman
- School of Biological Sciences, The University of Sydney, Sydney, Australia
- Centre for Mathematical Biology, The University of Sydney, Sydney, Australia
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8
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Pallotti F, Binelli G, Fabbri R, Valentino ML, Vicenti R, Macciocca M, Cevoli S, Baruzzi A, DiMauro S, Carelli V. A wide range of 3243A>G/tRNALeu(UUR) (MELAS) mutation loads may segregate in offspring through the female germline bottleneck. PLoS One 2014; 9:e96663. [PMID: 24805791 PMCID: PMC4013013 DOI: 10.1371/journal.pone.0096663] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 04/10/2014] [Indexed: 12/19/2022] Open
Abstract
Segregation of mutant mtDNA in human tissues and through the germline is debated, with no consensus about the nature and size of the bottleneck hypothesized to explain rapid generational shifts in mutant loads. We investigated two maternal lineages with an apparently different inheritance pattern of the same pathogenic mtDNA 3243A>G/tRNALeu(UUR) (MELAS) mutation. We collected blood cells, muscle biopsies, urinary epithelium and hair follicles from 20 individuals, as well as oocytes and an ovarian biopsy from one female mutation carrier, all belonging to the two maternal lineages to assess mutant mtDNA load, and calculated the theoretical germline bottleneck size (number of segregating units). We also evaluated “mother-to-offspring” segregations from the literature, for which heteroplasmy assessment was available in at least three siblings besides the proband. Our results showed that mutation load was prevalent in skeletal muscle and urinary epithelium, whereas in blood cells there was an inverse correlation with age, as previously reported. The histoenzymatic staining of the ovarian biopsy failed to show any cytochrome-c-oxidase defective oocyte. Analysis of four oocytes and one offspring from the same unaffected mother of the first family showed intermediate heteroplasmic mutant loads (10% to 75%), whereas very skewed loads of mutant mtDNA (0% or 81%) were detected in five offspring of another unaffected mother from the second family. Bottleneck size was 89 segregating units for the first mother and 84 for the second. This was remarkably close to 88, the number of “segregating units” in the “mother-to-offspring” segregations retrieved from literature. In conclusion, a wide range of mutant loads may be found in offspring tissues and oocytes, resulting from a similar theoretical bottleneck size.
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Affiliation(s)
- Francesco Pallotti
- Department of Neurology, Columbia University, New York City, New York, United States of America
- Dipartimento di Scienze Chirurgiche e Morfologiche, University of Insubria, Varese, Italy
| | - Giorgio Binelli
- Dipartimento di Scienze Teoriche e Applicate, University of Insubria, Varese, Italy
| | - Raffaella Fabbri
- Unità Operativa di Ginecologia e Fisiopatologia della Riproduzione Umana, Ospedale S.Orsola-Malpighi, University of Bologna, Bologna, Italy
- Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), University of Bologna, Bologna, Italy
| | - Maria L. Valentino
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, Bologna, Italy
- Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM), University of Bologna, Bologna, Italy
| | - Rossella Vicenti
- Unità Operativa di Ginecologia e Fisiopatologia della Riproduzione Umana, Ospedale S.Orsola-Malpighi, University of Bologna, Bologna, Italy
- Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), University of Bologna, Bologna, Italy
| | - Maria Macciocca
- Unità Operativa di Ginecologia e Fisiopatologia della Riproduzione Umana, Ospedale S.Orsola-Malpighi, University of Bologna, Bologna, Italy
- Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), University of Bologna, Bologna, Italy
| | - Sabina Cevoli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, Bologna, Italy
- Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM), University of Bologna, Bologna, Italy
| | - Agostino Baruzzi
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, Bologna, Italy
- Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM), University of Bologna, Bologna, Italy
| | - Salvatore DiMauro
- Department of Neurology, Columbia University, New York City, New York, United States of America
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, Bologna, Italy
- Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM), University of Bologna, Bologna, Italy
- * E-mail:
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9
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Wolken GG, Arriaga EA. Simultaneous measurement of individual mitochondrial membrane potential and electrophoretic mobility by capillary electrophoresis. Anal Chem 2014; 86:4217-26. [PMID: 24673334 PMCID: PMC4018156 DOI: 10.1021/ac403849x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
![]()
Mitochondrial membrane
potential varies, depending on energy demand,
subcellular location, and morphology and is commonly used as an indicator
of mitochondrial functional status. Electrophoretic mobility is a
heterogeneous surface property reflective of mitochondrial surface
composition and morphology, which could be used as a basis for separation
of mitochondrial subpopulations. Since these properties are heterogeneous,
methods for their characterization in individual mitochondria are
needed to better design and understand electrophoretic separations
of subpopulations of mitochondria. Here we report on the first method
for simultaneous determination of individual mitochondrial membrane
potential and electrophoretic mobility by capillary electrophoresis
with laser-induced fluorescence detection (CE-LIF). Mitochondria were
isolated from cultured cells, mouse muscle, or liver, and then polarized,
labeled with JC-1 (a ratiometric fluorescent probe, which indicates
changes in membrane potential), and separated with CE-LIF. Red/green
fluorescence intensity ratios from individual mitochondria were used
as an indicator of mitochondrial membrane potential. Reproducible
distributions of individual mitochondrial membrane potential and electrophoretic
mobility were observed. Analysis of polarized and depolarized regions
of interest defined using red/green ratios and runs of depolarized
controls allowed for the determination of membrane potential and comparison
of electrophoretic mobility distributions in preparations containing
depolarized mitochondria. Through comparison of these regions of interest,
we observed dependence of electrophoretic mobility on membrane potential,
with polarized regions of interest displaying decreased electrophoretic
mobility. This method could be applied to investigate mitochondrial
heterogeneity in aging or disease models where membrane potential
is an important factor.
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Affiliation(s)
- Gregory G Wolken
- Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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10
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Taylor TH, Frost NW, Bowser MT, Arriaga EA. Analysis of individual mitochondria via fluorescent immunolabeling with Anti-TOM22 antibodies. Anal Bioanal Chem 2014; 406:1683-91. [PMID: 24481619 DOI: 10.1007/s00216-013-7593-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 12/11/2013] [Accepted: 12/19/2013] [Indexed: 01/08/2023]
Abstract
Mitochondria are responsible for maintaining a variety of cellular functions. One such function is the interaction and subsequent import of proteins into these organelles via the translocase of outer membrane (TOM) complex. Antibodies have been used to analyze the presence and function of proteins comprising this complex, but have not been used to investigate variations in the abundance of TOM complex in mitochondria. Here, we report on the feasibility of using capillary cytometry with laser-induced fluorescence to detect mitochondria labeled with antibodies targeting the TOM complex and to estimate the number of antibodies that bind to these organelles. Mitochondria were fluorescently labeled with DsRed2, while antibodies targeting the TOM22 protein, one of nine proteins comprising the TOM complex, were conjugated to the Atto-488 fluorophore. At typical labeling conditions, 94% of DsRed2 mitochondria were also immunofluorescently labeled with Atto-488 Anti-TOM22 antibodies. The calculated median number of Atto-488 Anti-TOM22 antibodies bound to the surface of mitochondria was ∼2,000 per mitochondrion. The combination of fluorescent immunolabeling and capillary cytometry could be further developed to include multicolor labeling experiments, which enable monitoring several molecular targets at the same time in the same or different organelle types.
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Affiliation(s)
- Thane H Taylor
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
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11
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Wallace DC, Chalkia D. Mitochondrial DNA genetics and the heteroplasmy conundrum in evolution and disease. Cold Spring Harb Perspect Biol 2013; 5:a021220. [PMID: 24186072 PMCID: PMC3809581 DOI: 10.1101/cshperspect.a021220] [Citation(s) in RCA: 441] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The unorthodox genetics of the mtDNA is providing new perspectives on the etiology of the common "complex" diseases. The maternally inherited mtDNA codes for essential energy genes, is present in thousands of copies per cell, and has a very high mutation rate. New mtDNA mutations arise among thousands of other mtDNAs. The mechanisms by which these "heteroplasmic" mtDNA mutations come to predominate in the female germline and somatic tissues is poorly understood, but essential for understanding the clinical variability of a range of diseases. Maternal inheritance and heteroplasmy also pose major challengers for the diagnosis and prevention of mtDNA disease.
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Affiliation(s)
- Douglas C Wallace
- Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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12
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Distribution of mitochondrial nucleoids upon mitochondrial network fragmentation and network reintegration in HEPG2 cells. Int J Biochem Cell Biol 2012; 45:593-603. [PMID: 23220174 DOI: 10.1016/j.biocel.2012.11.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 11/02/2012] [Accepted: 11/28/2012] [Indexed: 01/22/2023]
Abstract
Mitochondrial DNA (mtDNA) is organized in nucleoids in complex with accessory proteins, proteins of mtDNA replication and gene expression machinery. A robust mtDNA genome is represented by hundreds to thousands of nucleoids in cell mitochondrion. Detailed information is lacking about the dynamics of nucleoid distribution within the mitochondrial network upon physiological and pathological events. Therefore, we used confocal microscopy to study mitochondrial nucleoid redistribution upon mitochondrial fission and following reintegration of the mitochondrial network. Fission was induced by oxidative stress at respiration inhibition by rotenone or upon elimination of the protonmotive force by uncoupling or upon canceling its electrical component, ΔΨ(m), by valinomycin; and by silencing of mitofusin MFN2. Agent withdrawal resulted in concomitant mitochondrial network reintegration. We found two major principal morphological states: (i) a tubular state of the mitochondrial network with equidistant nucleoid spacing, 1.10±0.2 nucleoids per μm, and (ii) a fragmented state of solitary spheroid objects in which several nucleoids were clustered. We rarely observed singular mitochondrial fragments with a single nucleoid inside and very seldom we observed empty fragments. Reintegration of fragments into the mitochondrial network re-established the tubular state with equidistant nucleoid spacing. The two major morphological states coexisted at intermediate stages. These observations suggest that both mitochondrial network fission and reconnection of the disintegrated network are nucleoid-centric, i.e., fission and new mitochondrial tubule formation are initiated around nucleoids. Analyses of combinations of these morphological icons thus provide a basis for a future mitochondrial morphology diagnostics.
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Satori CP, Kostal V, Arriaga EA. Review on recent advances in the analysis of isolated organelles. Anal Chim Acta 2012; 753:8-18. [PMID: 23107131 PMCID: PMC3484375 DOI: 10.1016/j.aca.2012.09.041] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 09/22/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
Abstract
The analysis of isolated organelles is one of the pillars of modern bioanalytical chemistry. This review describes recent developments on the isolation and characterization of isolated organelles both from living organisms and cell cultures. Salient reports on methods to release organelles focused on reproducibility and yield, membrane isolation, and integrated devices for organelle release. New developments on organelle fractionation after their isolation were on the topics of centrifugation, immunocapture, free flow electrophoresis, flow field-flow fractionation, fluorescence activated organelle sorting, laser capture microdissection, and dielectrophoresis. New concepts on characterization of isolated organelles included atomic force microscopy, optical tweezers combined with Raman spectroscopy, organelle sensors, flow cytometry, capillary electrophoresis, and microfluidic devices.
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Affiliation(s)
- Chad P Satori
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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14
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Zhang S, Zhu S, Yang L, Zheng Y, Gao M, Wang S, Zeng JZ, Yan X. High-Throughput Multiparameter Analysis of Individual Mitochondria. Anal Chem 2012; 84:6421-8. [DOI: 10.1021/ac301464x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Shuyue Zhang
- The Key Laboratory
of Analytical Science, The Key Laboratory for Chemical Biology of
Fujian Province, Department of Chemical Biology, College of Chemistry
and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
| | - Shaobin Zhu
- The Key Laboratory
of Analytical Science, The Key Laboratory for Chemical Biology of
Fujian Province, Department of Chemical Biology, College of Chemistry
and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
| | - Lingling Yang
- The Key Laboratory
of Analytical Science, The Key Laboratory for Chemical Biology of
Fujian Province, Department of Chemical Biology, College of Chemistry
and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
| | - Yan Zheng
- The Key Laboratory
of Analytical Science, The Key Laboratory for Chemical Biology of
Fujian Province, Department of Chemical Biology, College of Chemistry
and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
| | - Min Gao
- The Key Laboratory
of Analytical Science, The Key Laboratory for Chemical Biology of
Fujian Province, Department of Chemical Biology, College of Chemistry
and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
| | - Shuo Wang
- The Key Laboratory
of Analytical Science, The Key Laboratory for Chemical Biology of
Fujian Province, Department of Chemical Biology, College of Chemistry
and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
| | - Jin-zhang Zeng
- School of Pharmaceutical
Sciences and Institute for Biomedical Research, Xiamen University, People’s Republic of China
| | - Xiaomei Yan
- The Key Laboratory
of Analytical Science, The Key Laboratory for Chemical Biology of
Fujian Province, Department of Chemical Biology, College of Chemistry
and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
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15
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Anand RK, Chiu DT. Analytical tools for characterizing heterogeneity in organelle content. Curr Opin Chem Biol 2012; 16:391-9. [PMID: 22694875 DOI: 10.1016/j.cbpa.2012.05.187] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 05/10/2012] [Indexed: 11/16/2022]
Abstract
Heterogeneity in the content and function of subcellular organelles on the intercellular and intracellular level plays an important role in determining cell fate. These variations extend to normal-state and disease-state cellular functions and responses to environmental stimuli, such as oxidative stress and therapeutic drugs. Analytical tools to characterize variation in all types of organelles are essential to provide insights that can lead to advances in medicine, such as therapies targeted to specific subcellular regions. In this review, we discuss analytical techniques for interrogating individual intact organelles (e.g. mitochondria and synaptic vesicles) and lysates in a high-throughput manner, including a recently developed nanoscale fluorescence-activated subcellular sorter and techniques based on capillary electrophoresis with laser-induced fluorescence detection. We then highlight the advantages that droplet microfluidics offers for probing subcellular heterogeneity.
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Affiliation(s)
- Robbyn K Anand
- Department of Chemistry, University of Washington, Seattle, WA 98195-1700, USA
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Brown RB, Hewel JA, Emili A, Audet J. Identification of enzyme-converted peptide products from single cells using capillary electrophoresis and liquid chromatography-mass spectrometry. Methods Mol Biol 2012; 853:17-28. [PMID: 22323137 DOI: 10.1007/978-1-61779-567-1_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Single-cell analysis using chemical methods, otherwise known as chemical cytometry, promises to provide significant leaps in understanding signaling processes which result in cellular behavior. Sensitive methods for chemical cytometry such as capillary electrophoresis can detect and quantify multiple targets; however, conclusive identification of detected analytes is required for useful data to be obtained. Here, we demonstrate a method for determining the identity of enzyme-converted peptide products from single cells using a combination of capillary electrophoresis and liquid chromatography-mass spectrometry (LC-MS).
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Affiliation(s)
- Robert B Brown
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, ON, Canada
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17
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Bogenhagen DF. Mitochondrial DNA nucleoid structure. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:914-20. [PMID: 22142616 DOI: 10.1016/j.bbagrm.2011.11.005] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 11/13/2011] [Accepted: 11/16/2011] [Indexed: 12/21/2022]
Abstract
Eukaryotic cells are characterized by their content of intracellular membrane-bound organelles, including mitochondria as well as nuclei. These two DNA-containing compartments employ two distinct strategies for storage and readout of genetic information. The diploid nuclei of human cells contain about 6 billion base pairs encoding about 25,000 protein-encoding genes, averaging 120 kB/gene, packaged in chromatin arranged as a regular nucleosomal array. In contrast, human cells contain hundreds to thousands of copies of a ca.16 kB mtDNA genome tightly packed with 13 protein-coding genes along with rRNA and tRNA genes required for their expression. The mtDNAs are dispersed throughout the mitochondrial network as histone-free nucleoids containing single copies or small clusters of genomes. This review will summarize recent advances in understanding the microscopic structure and molecular composition of mtDNA nucleoids in higher eukaryotes. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
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Affiliation(s)
- Daniel F Bogenhagen
- Department of Pharmacological Sciences, State University of New York at Stony Brook, Stony Brook, NY 11794-8651, USA.
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18
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The implications of mitochondrial DNA copy number regulation during embryogenesis. Mitochondrion 2011; 11:686-92. [PMID: 21635974 DOI: 10.1016/j.mito.2011.05.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 04/20/2011] [Accepted: 05/18/2011] [Indexed: 11/21/2022]
Abstract
Mutations of mitochondrial DNA (mtDNA) cause a wide array of multisystem disorders, particularly affecting organs with high energy demands. Typically only a proportion of the total mtDNA content is mutated (heteroplasmy), and high percentage levels of mutant mtDNA are associated with a more severe clinical phenotype. MtDNA is inherited maternally and the heteroplasmy level in each one of the offspring is often very different to that found in the mother. The mitochondrial genetic bottleneck hypothesis was first proposed as the explanation for these observations over 20 years ago. Although the precise bottleneck mechanism is still hotly debated, the regulation of cellular mtDNA content is a key issue. Here we review current understanding of the factors regulating the amount of mtDNA within cells and discuss the relevance of these findings to our understanding of the inheritance of mtDNA heteroplasmy.
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Abstract
Mitochondria are highly heterogeneous organelles that likely have unique isoelectric points (pI), which are related to their surface compositions and could be exploited in their purification and isolation. Previous methods to determine pI of mitochondria report an average pI. This article is the first report of the determination of the isoelectric points of individual mitochondria by capillary isoelectric focusing (cIEF). In this method, mitochondria labeled with the mitochondrial-specific probe 10-N-nonyl acridine orange (NAO) are injected into a fused-silica capillary in a solution of carrier ampholytes at physiological pH and osmolarity, where they are focused then chemically mobilized and detected by laser-induced fluorescence (LIF). Fluorescein-derived pI markers are used as internal standards to assign a pI value to each individually detected mitochondrial event, and a mitochondrial pI distribution is determined. This method provides reproducible distributions of individual mitochondrial pI, accurate determination of the pI of individual mitochondria by the use of internal standards, and resolution of 0.03 pH units between individual mitochondria. This method could also be applied to investigate or design separations of organelle subtypes (e.g., subsarcolemmal and interfibrillar skeletal muscle mitochondria) and to determine the pIs of other biological or nonbiological particles.
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Affiliation(s)
- Gregory G. Wolken
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA 55455
| | - Vratislav Kostal
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA 55455
| | - Edgar A. Arriaga
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA 55455
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Reiner JE, Kishore RB, Levin BC, Albanetti T, Boire N, Knipe A, Helmerson K, Deckman KH. Detection of heteroplasmic mitochondrial DNA in single mitochondria. PLoS One 2010; 5:e14359. [PMID: 21179558 PMCID: PMC3002942 DOI: 10.1371/journal.pone.0014359] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 10/27/2010] [Indexed: 01/11/2023] Open
Abstract
Background Mitochondrial DNA (mtDNA) genome mutations can lead to energy and respiratory-related disorders like myoclonic epilepsy with ragged red fiber disease (MERRF), mitochondrial myopathy, encephalopathy, lactic acidosis and stroke (MELAS) syndrome, and Leber's hereditary optic neuropathy (LHON). It is not well understood what effect the distribution of mutated mtDNA throughout the mitochondrial matrix has on the development of mitochondrial-based disorders. Insight into this complex sub-cellular heterogeneity may further our understanding of the development of mitochondria-related diseases. Methodology This work describes a method for isolating individual mitochondria from single cells and performing molecular analysis on that single mitochondrion's DNA. An optical tweezer extracts a single mitochondrion from a lysed human HL-60 cell. Then a micron-sized femtopipette tip captures the mitochondrion for subsequent analysis. Multiple rounds of conventional DNA amplification and standard sequencing methods enable the detection of a heteroplasmic mixture in the mtDNA from a single mitochondrion. Significance Molecular analysis of mtDNA from the individually extracted mitochondrion demonstrates that a heteroplasmy is present in single mitochondria at various ratios consistent with the 50/50 heteroplasmy ratio found in single cells that contain multiple mitochondria.
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Affiliation(s)
- Joseph E Reiner
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America.
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