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Françoso E, Zuntini AR, Ricardo PC, Araújo NS, Silva JPN, Brown MJF, Arias MC. The complete mitochondrial genome of Trigonisca nataliae (Hymenoptera, Apidae) assemblage reveals heteroplasmy in the control region. Gene 2023:147621. [PMID: 37419430 DOI: 10.1016/j.gene.2023.147621] [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: 04/25/2023] [Revised: 06/13/2023] [Accepted: 07/05/2023] [Indexed: 07/09/2023]
Abstract
The evolution of mitochondrial genomes in the stingless bees is surprisingly dynamic, making them a model system to understand mitogenome structure, function, and evolution. Out of the seven mitogenomes available in this group, five exhibit atypical characteristics, including extreme rearrangements, rapid evolution and complete mitogenome duplication. To further explore the mitogenome diversity in these bees, we utilized isolated mtDNA and Illumina sequencing to assemble the complete mitogenome of Trigonisca nataliae, a species found in Northern Brazil. The mitogenome of T. nataliae was highly conserved in gene content and structure when compared to Melipona species but diverged in the control region (CR). Using PCR amplification, cloning and Sanger sequencing, six different CR haplotypes, varying in size and content, were recovery. These findings indicate that heteroplasmy, where different mitochondrial haplotypes coexist within individuals, occurs in T. nataliae. Consequently, we argue that heteroplasmy might indeed be a common phenomenon in bees that could be associated with variations in mitogenome size and challenges encountered during the assembly process.
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Affiliation(s)
- Elaine Françoso
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, TW20 0EX, UK; Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 05508-090, Brazil.
| | | | - Paulo Cseri Ricardo
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 05508-090, Brazil
| | - Natália Souza Araújo
- Unit of Evolutionary Biology & Ecology, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - João Paulo Naldi Silva
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 05508-090, Brazil
| | - Mark J F Brown
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Maria Cristina Arias
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 05508-090, Brazil
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2
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Tarasenko TA, Koulintchenko MV. Heterogeneity of the Mitochondrial Population in Cells of Plants and Other Organisms. Mol Biol 2022. [DOI: 10.1134/s0026893322020157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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Lujan SA, Longley MJ, Humble MH, Lavender CA, Burkholder A, Blakely EL, Alston CL, Gorman GS, Turnbull DM, McFarland R, Taylor RW, Kunkel TA, Copeland WC. Ultrasensitive deletion detection links mitochondrial DNA replication, disease, and aging. Genome Biol 2020; 21:248. [PMID: 32943091 PMCID: PMC7500033 DOI: 10.1186/s13059-020-02138-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 08/07/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Acquired human mitochondrial genome (mtDNA) deletions are symptoms and drivers of focal mitochondrial respiratory deficiency, a pathological hallmark of aging and late-onset mitochondrial disease. RESULTS To decipher connections between these processes, we create LostArc, an ultrasensitive method for quantifying deletions in circular mtDNA molecules. LostArc reveals 35 million deletions (~ 470,000 unique spans) in skeletal muscle from 22 individuals with and 19 individuals without pathogenic variants in POLG. This nuclear gene encodes the catalytic subunit of replicative mitochondrial DNA polymerase γ. Ablation, the deleted mtDNA fraction, suffices to explain skeletal muscle phenotypes of aging and POLG-derived disease. Unsupervised bioinformatic analyses reveal distinct age- and disease-correlated deletion patterns. CONCLUSIONS These patterns implicate replication by DNA polymerase γ as the deletion driver and suggest little purifying selection against mtDNA deletions by mitophagy in postmitotic muscle fibers. Observed deletion patterns are best modeled as mtDNA deletions initiated by replication fork stalling during strand displacement mtDNA synthesis.
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Affiliation(s)
- Scott A Lujan
- Genome Integrity and Structural Biology Laboratory, DNA Replication Fidelity Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Matthew J Longley
- Genome Integrity and Structural Biology Laboratory, Mitochondrial DNA Replication Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Margaret H Humble
- Genome Integrity and Structural Biology Laboratory, Mitochondrial DNA Replication Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Christopher A Lavender
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Adam Burkholder
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Grainne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, DNA Replication Fidelity Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, Mitochondrial DNA Replication Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
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4
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Malena A, Pantic B, Borgia D, Sgarbi G, Solaini G, Holt IJ, Spinazzola A, Perissinotto E, Sandri M, Baracca A, Vergani L. Mitochondrial quality control: Cell-type-dependent responses to pathological mutant mitochondrial DNA. Autophagy 2016; 12:2098-2112. [PMID: 27627835 DOI: 10.1080/15548627.2016.1226734] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Pathological mutations in the mitochondrial DNA (mtDNA) produce a diverse range of tissue-specific diseases and the proportion of mutant mitochondrial DNA can increase or decrease with time via segregation, dependent on the cell or tissue type. Previously we found that adenocarcinoma (A549.B2) cells favored wild-type (WT) mtDNA, whereas rhabdomyosarcoma (RD.Myo) cells favored mutant (m3243G) mtDNA. Mitochondrial quality control (mtQC) can purge the cells of dysfunctional mitochondria via mitochondrial dynamics and mitophagy and appears to offer the perfect solution to the human diseases caused by mutant mtDNA. In A549.B2 and RD.Myo cybrids, with various mutant mtDNA levels, mtQC was explored together with macroautophagy/autophagy and bioenergetic profile. The 2 types of tumor-derived cell lines differed in bioenergetic profile and mitophagy, but not in autophagy. A549.B2 cybrids displayed upregulation of mitophagy, increased mtDNA removal, mitochondrial fragmentation and mitochondrial depolarization on incubation with oligomycin, parameters that correlated with mutant load. Conversely, heteroplasmic RD.Myo lines had lower mitophagic markers that negatively correlated with mutant load, combined with a fully polarized and highly fused mitochondrial network. These findings indicate that pathological mutant mitochondrial DNA can modulate mitochondrial dynamics and mitophagy in a cell-type dependent manner and thereby offer an explanation for the persistence and accumulation of deleterious variants.
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Affiliation(s)
- Adriana Malena
- a Department of Neurosciences , University of Padova , Italy
| | - Boris Pantic
- a Department of Neurosciences , University of Padova , Italy
| | - Doriana Borgia
- a Department of Neurosciences , University of Padova , Italy
| | - Gianluca Sgarbi
- b Department of Biomedical and Neuromotor Sciences , University of Bologna , Italy
| | - Giancarlo Solaini
- b Department of Biomedical and Neuromotor Sciences , University of Bologna , Italy
| | - Ian J Holt
- c Medical Research Council, Mill Hill Laboratory , London , United Kingdom
| | | | - Egle Perissinotto
- d Department of Cardiac, Thoracic and Vascular Sciences, Biostatistics, Epidemiology and Public Health Unit , University of Padova , Padova , Italy
| | - Marco Sandri
- e Department of Biomedical Sciences , University of Padova , Italy.,f Venetian Institute of Molecular Medicine , Padova , Italy
| | - Alessandra Baracca
- b Department of Biomedical and Neuromotor Sciences , University of Bologna , Italy
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5
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Czajka A, Ajaz S, Gnudi L, Parsade CK, Jones P, Reid F, Malik AN. Altered Mitochondrial Function, Mitochondrial DNA and Reduced Metabolic Flexibility in Patients With Diabetic Nephropathy. EBioMedicine 2015; 2:499-512. [PMID: 26288815 PMCID: PMC4534759 DOI: 10.1016/j.ebiom.2015.04.002] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 03/27/2015] [Accepted: 04/03/2015] [Indexed: 01/09/2023] Open
Abstract
The purpose of this study was to determine if mitochondrial dysfunction plays a role in diabetic nephropathy (DN), a kidney disease which affects > 100 million people worldwide and is a leading cause of renal failure despite therapy. A cross-sectional study comparing DN with diabetes patients without kidney disease (DC) and healthy controls (HCs); and renal mesangial cells (HMCs) grown in normal and high glucose, was carried out. Patients with diabetes (DC) had increased circulating mitochondrial DNA (MtDNA), and HMCs increased their MtDNA within 24 h of hyperglycaemia. The increased MtDNA content in DCs and HMCs was not functional as transcription was unaltered/down-regulated, and MtDNA damage was present. MtDNA was increased in DC compared to HC, conversely, patients with DN had lower MtDNA than DC. Hyperglycaemic HMCs had fragmented mitochondria and TLR9 pathway activation, and in diabetic patients, mitophagy was reduced. Despite MtDNA content and integrity changing within 4 days, hyperglycaemic HMCs had a normal bio-energetic profile until 8 days, after which mitochondrial metabolism was progressively impaired. Peripheral blood mononuclear cells (PBMCs) from DN patients had reduced reserve capacity and maximal respiration, loss of metabolic flexibility and reduced Bioenergetic Health Index (BHI) compared to DC. Our data show that MtDNA changes precede bioenergetic dysfunction and that patients with DN have impaired mitochondrial metabolism compared to DC, leading us to propose that systemic mitochondrial dysfunction initiated by glucose induced MtDNA damage may be involved in the development of DN. Longitudinal studies are needed to define a potential cause–effect relationship between changes in MtDNA and bioenergetics in DN. Diabetic nephropathy may be a disease of acquired MtDNA damage and bioenergetic deficit. MtDNA content is increased in blood cells of diabetes patients and hyperglycaemic renal cells. Hyperglycaemia leads to renal cell MtDNA damage and subsequent bioenergetic dysfunction. Diabetic nephropathy patients have reduced circulating MtDNA , BHI and metabolic flexibility bioenergetic dysfunction and reduced metabolic flexibility and BHI.
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Affiliation(s)
- Anna Czajka
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | - Saima Ajaz
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | | | - Chandani Kiran Parsade
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | - Peter Jones
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | - Fiona Reid
- Department of Primary Care and Public Health Sciences
| | - Afshan N Malik
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
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6
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Lombès A, Auré K, Bellanné-Chantelot C, Gilleron M, Jardel C. Unsolved issues related to human mitochondrial diseases. Biochimie 2013; 100:171-6. [PMID: 23973280 DOI: 10.1016/j.biochi.2013.08.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/10/2013] [Indexed: 12/21/2022]
Abstract
Human mitochondrial diseases, defined as the diseases due to a mitochondrial oxidative phosphorylation defect, represent a large group of very diverse diseases with respect to phenotype and genetic causes. They present with many unsolved issues, the comprehensive analysis of which is beyond the scope of this review. We here essentially focus on the mechanisms underlying the diversity of targeted tissues, which is an important component of the large panel of these diseases phenotypic expression. The reproducibility of genotype/phenotype expression, the presence of modifying factors, and the potential causes for the restricted pattern of tissular expression are reviewed. Special emphasis is made on heteroplasmy, a specific feature of mitochondrial diseases, defined as the coexistence within the cell of mutant and wild type mitochondrial DNA molecules. Its existence permits unequal segregation during mitoses of the mitochondrial DNA populations and consequently heterogeneous tissue distribution of the mutation load. The observed tissue distributions of recurrent human mitochondrial DNA deleterious mutations are diverse but reproducible for a given mutation demonstrating that the segregation is not a random process. Its extent and mechanisms remain essentially unknown despite recent advances obtained in animal models.
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Affiliation(s)
- Anne Lombès
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; Université Paris-Descartes-Paris5, Paris F-75014, France; AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
| | - Karine Auré
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; AP-HP, Hôpital Ambroise Paré, Service d'explorations fonctionnelles, Boulogne-Billancourt F-92100, France; Université Versailles-Saint-Quentin en Yvelines, Faculté de Médecine, F-78180, France.
| | - Christine Bellanné-Chantelot
- AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
| | - Mylène Gilleron
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
| | - Claude Jardel
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
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7
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Dudu A, Georgescu SE, Berrebi P, Costache M. Site heteroplasmy in the mitochondrial cytochrome b gene of the sterlet sturgeon Acipenser ruthenus. Genet Mol Biol 2012; 35:886-91. [PMID: 23271951 PMCID: PMC3526098 DOI: 10.1590/s1415-47572012005000058] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 07/05/2012] [Indexed: 11/24/2022] Open
Abstract
Sturgeons are fish species with a complex biology. They are also characterized by complex aspects including polyploidization and easiness of hybridization. As with most of the Ponto-Caspian sturgeons, the populations of Acipenser ruthenus from the Danube have declined drastically during the last decades. This is the first report on mitochondrial point heteroplasmy in the cytochrome b gene of this species. The 1141 bp sequence of the cytb gene in wild sterlet sturgeon individuals from the Lower Danube was determined, and site heteroplasmy evidenced in three of the 30 specimens collected. Two nucleotide sequences were identified in these heteroplasmic individuals. The majority of the heteroplasmic sites are synonymous and do not modify the sequence of amino acids in cytochrome B protein. To date, several cases of point heteroplasmy have been reported in animals, mostly due to paternal leakage of mtDNA. The presence of specific point heteroplasmic sites might be interesting for a possible correlation with genetically distinct groups in the Danube River.
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Affiliation(s)
- Andreea Dudu
- Department of Biochemistry and Molecular Biology, University of Bucharest, Bucharest, Romania
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8
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Raap AK, Jahangir Tafrechi RS, van de Rijke FM, Pyle A, Wählby C, Szuhai K, Ravelli RBG, de Coo RFM, Rajasimha HK, Nilsson M, Chinnery PF, Samuels DC, Janssen GMC. Non-random mtDNA segregation patterns indicate a metastable heteroplasmic segregation unit in m.3243A>G cybrid cells. PLoS One 2012; 7:e52080. [PMID: 23272214 PMCID: PMC3525564 DOI: 10.1371/journal.pone.0052080] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 11/08/2012] [Indexed: 01/07/2023] Open
Abstract
Many pathogenic mitochondrial DNA mutations are heteroplasmic, with a mixture of mutated and wild-type mtDNA present within individual cells. The severity and extent of the clinical phenotype is largely due to the distribution of mutated molecules between cells in different tissues, but mechanisms underpinning segregation are not fully understood. To facilitate mtDNA segregation studies we developed assays that measure m.3243A>G point mutation loads directly in hundreds of individual cells to determine the mechanisms of segregation over time. In the first study of this size, we observed a number of discrete shifts in cellular heteroplasmy between periods of stable heteroplasmy. The observed patterns could not be parsimoniously explained by random mitotic drift of individual mtDNAs. Instead, a genetically metastable, heteroplasmic mtDNA segregation unit provides the likely explanation, where stable heteroplasmy is maintained through the faithful replication of segregating units with a fixed wild-type/m.3243A>G mutant ratio, and shifts occur through the temporary disruption and re-organization of the segregation units. While the nature of the physical equivalent of the segregation unit remains uncertain, the factors regulating its organization are of major importance for the pathogenesis of mtDNA diseases.
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Affiliation(s)
- Anton K. Raap
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | | | - Frans M. van de Rijke
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Carolina Wählby
- Imaging Platform, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Centre for Image Analysis, Uppsala University, Uppsala, Sweden
| | - Karoly Szuhai
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Raimond B. G. Ravelli
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | - René F. M. de Coo
- Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Harsha K. Rajasimha
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Mats Nilsson
- Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Patrick F. Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David C. Samuels
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - George M. C. Janssen
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
- * E-mail:
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9
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Munwes I, Geffen E, Friedmann A, Tikochinski Y, Gafny S. Variation in repeat length and heteroplasmy of the mitochondrial DNA control region along a core-edge gradient in the eastern spadefoot toad (Pelobates syriacus). Mol Ecol 2011; 20:2878-87. [PMID: 21645158 DOI: 10.1111/j.1365-294x.2011.05134.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Peripheral populations are those situated at the distribution margins of a species and are often subjected to more extreme abiotic and biotic conditions than those at the core. Here, we hypothesized that shorter repeat length and fewer heteroplasmic mitochondrial DNA (mtDNA) copies, which are associated with more efficient mitochondrial function, may be related to improved survival under extreme environmental conditions. We sampled eastern spadefoot toads (mostly as tadpoles) from 43 rain pools distributed along a 300-km gradient from core to edge of the species' distribution. We show that mean pool tandem repeat length and heteroplasmy increase from edge to core, even after controlling for body size. We evaluate several alternative hypotheses and propose the Fisher hypothesis as the most likely explanation. However, additional sequential sampling and experimental studies are required to determine whether selection under extreme conditions, or alternative mechanisms, could account for the gradient in heteroplasmy and repeat length in the mtDNA control region.
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Affiliation(s)
- Inbar Munwes
- School of Marine Sciences, Ruppin Academic Center, Michmoret 40297, Israel
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10
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Yu-Wai-Man P, Griffiths PG, Chinnery PF. Mitochondrial optic neuropathies - disease mechanisms and therapeutic strategies. Prog Retin Eye Res 2011; 30:81-114. [PMID: 21112411 PMCID: PMC3081075 DOI: 10.1016/j.preteyeres.2010.11.002] [Citation(s) in RCA: 431] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal-dominant optic atrophy (DOA) are the two most common inherited optic neuropathies in the general population. Both disorders share striking pathological similarities, marked by the selective loss of retinal ganglion cells (RGCs) and the early involvement of the papillomacular bundle. Three mitochondrial DNA (mtDNA) point mutations; m.3460G>A, m.11778G>A, and m.14484T>C account for over 90% of LHON cases, and in DOA, the majority of affected families harbour mutations in the OPA1 gene, which codes for a mitochondrial inner membrane protein. Optic nerve degeneration in LHON and DOA is therefore due to disturbed mitochondrial function and a predominantly complex I respiratory chain defect has been identified using both in vitro and in vivo biochemical assays. However, the trigger for RGC loss is much more complex than a simple bioenergetic crisis and other important disease mechanisms have emerged relating to mitochondrial network dynamics, mtDNA maintenance, axonal transport, and the involvement of the cytoskeleton in maintaining a differential mitochondrial gradient at sites such as the lamina cribosa. The downstream consequences of these mitochondrial disturbances are likely to be influenced by the local cellular milieu. The vulnerability of RGCs in LHON and DOA could derive not only from tissue-specific, genetically-determined biological factors, but also from an increased susceptibility to exogenous influences such as light exposure, smoking, and pharmacological agents with putative mitochondrial toxic effects. Our concept of inherited mitochondrial optic neuropathies has evolved over the past decade, with the observation that patients with LHON and DOA can manifest a much broader phenotypic spectrum than pure optic nerve involvement. Interestingly, these phenotypes are sometimes clinically indistinguishable from other neurodegenerative disorders such as Charcot-Marie-Tooth disease, hereditary spastic paraplegia, and multiple sclerosis, where mitochondrial dysfunction is also thought to be an important pathophysiological player. A number of vertebrate and invertebrate disease models has recently been established to circumvent the lack of human tissues, and these have already provided considerable insight by allowing direct RGC experimentation. The ultimate goal is to translate these research advances into clinical practice and new treatment strategies are currently being investigated to improve the visual prognosis for patients with mitochondrial optic neuropathies.
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MESH Headings
- Animals
- DNA, Mitochondrial/genetics
- Disease Models, Animal
- Humans
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Autosomal Dominant/physiopathology
- Optic Atrophy, Autosomal Dominant/therapy
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/physiopathology
- Optic Atrophy, Hereditary, Leber/therapy
- Optic Nerve/pathology
- Phenotype
- Point Mutation
- Retinal Ganglion Cells/pathology
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Affiliation(s)
- Patrick Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, UK.
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11
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Evdokimovsky EV, Ushakova TE, Kudriavtcev AA, Gaziev AI. Alteration of mtDNA copy number, mitochondrial gene expression and extracellular DNA content in mice after irradiation at lethal dose. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2011; 50:181-188. [PMID: 20814800 DOI: 10.1007/s00411-010-0329-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Accepted: 08/23/2010] [Indexed: 05/29/2023]
Abstract
High steady-state transcriptional activity is essential for normal mitochondrial function. The requisite transcription rate is satisfied in part by high copy number of mitochondrial DNA (mtDNA). In the present study, we analyze mtDNA copy number by real-time PCR in nucleated blood cells from control mice and mice exposed to 1- or 10-Gy X-radiation. Transcription of the oxidative phosphorylation-associated genes cytb, atp6, nd4, nd2 and d-loop region was monitored in these nucleated blood cells similarly by real-time PCR. We observed a 50% decrease in the ratio of mitochondrial to nuclear DNA (mtDNA/nDNA) in blood cells, while the mtDNA/nDNA ratio in serum increased. After a lethal 10-Gy dose of X-irradiation, we observed an 80% decrease in the number of circulating lymphocytes. In response to a 10-Gy radiation dose, we observed transiently increased mtDNA/nDNA ratio and transcription within the initial 5 h post-treatment. At 24-72 h, the mtDNA/nDNA ratio in surviving cells was reduced to the level observed in blood cells irradiated with 1 Gy. We observed a decrease in the serum mtDNA/nDNA ratio due to an increase in nDNA content rather than a decrease in mtDNA. Taken together, results presented herein suggest that the mtDNA/nDNA ratio may be of clinical value potentially as a diagnostic tool, particularly in oncology patients undergoing radiation therapy.
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Affiliation(s)
- Edward V Evdokimovsky
- Laboratory of Radiation and Molecular Biology, Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, Instituskaya St., Pushchino, 142290, Russia.
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12
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Magnacca KN, Brown MJF. Mitochondrial heteroplasmy and DNA barcoding in Hawaiian Hylaeus (Nesoprosopis) bees (Hymenoptera: Colletidae). BMC Evol Biol 2010; 10:174. [PMID: 20540728 PMCID: PMC2891727 DOI: 10.1186/1471-2148-10-174] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 06/11/2010] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The past several years have seen a flurry of papers seeking to clarify the utility and limits of DNA barcoding, particularly in areas such as species discovery and paralogy due to nuclear pseudogenes. Heteroplasmy, the coexistence of multiple mitochondrial haplotypes in a single organism, has been cited as a potentially serious problem for DNA barcoding but its effect on identification accuracy has not been tested. In addition, few studies of barcoding have tested a large group of closely-related species with a well-established morphological taxonomy. In this study we examine both of these issues, by densely sampling the Hawaiian Hylaeus bee radiation. RESULTS Individuals from 21 of the 49 a priori morphologically-defined species exhibited coding sequence heteroplasmy at levels of 1-6% or more. All homoplasmic species were successfully identified by COI using standard methods of analysis, but only 71% of heteroplasmic species. The success rate in identifying heteroplasmic species was increased to 86% by treating polymorphisms as character states rather than ambiguities. Nuclear pseudogenes (numts) were also present in four species, and were distinguishable from heteroplasmic sequences by patterns of nucleotide and amino acid change. CONCLUSIONS Heteroplasmy significantly decreased the reliability of species identification. In addition, the practical issue of dealing with large numbers of polymorphisms- and resulting increased time and labor required - makes the development of DNA barcode databases considerably more complex than has previously been suggested. The impact of heteroplasmy on the utility of DNA barcoding as a bulk specimen identification tool will depend upon its frequency across populations, which remains unknown. However, DNA barcoding is still likely to remain an important identification tool for those species that are difficult or impossible to identify through morphology, as is the case for the ecologically important solitary bee fauna.
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Affiliation(s)
- Karl N Magnacca
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
- Current address: Department of Biology, University of Hawai'i, 200 W. Kawili St., Hilo HI 96720, USA
| | - Mark JF Brown
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
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Magnacca KN, Brown MJF. Tissue segregation of mitochondrial haplotypes in heteroplasmic Hawaiian bees: implications for DNA barcoding. Mol Ecol Resour 2009; 10:60-8. [PMID: 21564991 DOI: 10.1111/j.1755-0998.2009.02724.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The issue of mitochondrial heteroplasmy has been cited as a theoretical problem for DNA barcoding but is only beginning to be examined in natural systems. We sequenced multiple DNA extractions from 20 individuals of four Hawaiian Hylaeus bee species known to be heteroplasmic. All species showed strong differences at polymorphic sites between abdominal and muscle tissue in most individuals, and only two individuals had no obvious segregation. Two specimens produced completely clean sequences from abdominal DNA. The fact that these differences are clearly visible by direct sequencing indicates that substantial intra-individual mtDNA diversity may be overlooked when DNA is taken from small tissue fragments. At the same time, differences in haplotype distribution among individuals may result in incorrect recognition of cryptic species. Because DNA barcoding studies typically use only a small fragment of an organism, they are particularly vulnerable to sequencing bias where heteroplasmy and haplotype segregation are present. It is important to anticipate this possibility prior to undertaking large-scale barcoding projects to reduce the likelihood of haplotype segregation confounding the results.
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Affiliation(s)
- Karl N Magnacca
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
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Doublet V, Souty-Grosset C, Bouchon D, Cordaux R, Marcadé I. A thirty million year-old inherited heteroplasmy. PLoS One 2008; 3:e2938. [PMID: 18698356 PMCID: PMC2491557 DOI: 10.1371/journal.pone.0002938] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 07/14/2008] [Indexed: 11/18/2022] Open
Abstract
Due to essentially maternal inheritance and a bottleneck effect during early oogenesis, newly arising mitochondrial DNA (mtDNA) mutations segregate rapidly in metazoan female germlines. Consequently, heteroplasmy (i.e. the mixture of mtDNA genotypes within an organism) is generally resolved to homoplasmy within a few generations. Here, we report an exceptional transpecific heteroplasmy (predicting an alanine/valine alloacceptor tRNA change) that has been stably inherited in oniscid crustaceans for at least thirty million years. Our results suggest that this heteroplasmy is stably transmitted across generations because it occurs within mitochondria and therefore escapes the mtDNA bottleneck that usually erases heteroplasmy. Consistently, at least two oniscid species possess an atypical trimeric mitochondrial genome, which provides an adequate substrate for the emergence of a constitutive intra-mitochondrial heteroplasmy. Persistence of a mitochondrial polymorphism on such a deep evolutionary timescale suggests that balancing selection may be shaping mitochondrial sequence evolution in oniscid crustaceans.
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Affiliation(s)
- Vincent Doublet
- Université de Poitiers, Laboratoire Ecologie, Evolution, Symbiose, UMR CNRS 6556, Poitiers, France
| | - Catherine Souty-Grosset
- Université de Poitiers, Laboratoire Ecologie, Evolution, Symbiose, UMR CNRS 6556, Poitiers, France
| | - Didier Bouchon
- Université de Poitiers, Laboratoire Ecologie, Evolution, Symbiose, UMR CNRS 6556, Poitiers, France
| | - Richard Cordaux
- Université de Poitiers, Laboratoire Ecologie, Evolution, Symbiose, UMR CNRS 6556, Poitiers, France
| | - Isabelle Marcadé
- Université de Poitiers, Laboratoire Ecologie, Evolution, Symbiose, UMR CNRS 6556, Poitiers, France
- * E-mail:
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Tafrechi RSJ, van de Rijke FM, Allallou A, Larsson C, Sloos WCR, van de Sande M, Wählby C, Janssen GMC, Raap AK. Single-cell A3243G mitochondrial DNA mutation load assays for segregation analysis. J Histochem Cytochem 2007; 55:1159-66. [PMID: 17679731 PMCID: PMC3957535 DOI: 10.1369/jhc.7a7282.2007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Segregation of mitochondrial DNA (mtDNA) is an important underlying pathogenic factor in mtDNA mutation accumulation in mitochondrial diseases and aging, but the molecular mechanisms of mtDNA segregation are elusive. Lack of high-throughput single-cell mutation load assays lies at the root of the paucity of studies in which, at the single-cell level, mitotic mtDNA segregation patterns have been analyzed. Here we describe development of a novel fluorescence-based, non-gel PCR restriction fragment length polymorphism method for single-cell A3243G mtDNA mutation load measurement. Results correlated very well with a quantitative in situ Padlock/rolling circle amplification-based genotyping method. In view of the throughput and accuracy of both methods for single-cell A3243G mtDNA mutation load determination, we conclude that they are well suited for segregation analysis.
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Affiliation(s)
| | - Frans M. van de Rijke
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Amin Allallou
- Center for Image AnalysisUppsala University, Uppsala, Sweden
| | - Chatarina Larsson
- Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Willem C. R. Sloos
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marchien van de Sande
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Carolina Wählby
- Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden
- Center for Image AnalysisUppsala University, Uppsala, Sweden
| | - George M. C. Janssen
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Anton K. Raap
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
- Correspondence to: Anton K. Raap, Department of Molecular Cell Biology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands. E-mail:
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Kmiec B, Woloszynska M, Janska H. Heteroplasmy as a common state of mitochondrial genetic information in plants and animals. Curr Genet 2006; 50:149-59. [PMID: 16763846 DOI: 10.1007/s00294-006-0082-1] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 05/11/2006] [Accepted: 05/13/2006] [Indexed: 10/24/2022]
Abstract
Plant and animal mitochondrial genomes, although quite distinct in size, structure, expression and evolutionary dynamics both may exhibit the state of heteroplasmy--the presence of more than one type of mitochondrial genome in an organism. This review is focused on heteroplasmy in plants, but we also highlight the most striking similarities and differences between plant and animal heteroplasmy. First we summarize the information on heteroplasmy generation and methods of its detection. Then we describe examples of quantitative changes in heteroplasmic populations of mitochondrial DNA (mtDNA) and consequences of such events. We also summarize the current knowledge about transmission and somatic segregation of heteroplasmy in plants and animals. Finally, factors which influence the stoichiometry of heteroplasmic mtDNA variants are discussed. Despite the apparent differences between the plant and animal heteroplasmy, the observed similarities allow one to conclude that this condition must play an important role in the mitochondrial biology of living organisms.
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Affiliation(s)
- Beata Kmiec
- Institute of Biochemistry and Molecular Biology, Department of Cell Molecular Biology, University of Wroclaw, ul Przybyszewskiego 63/77, Wroclaw, Poland
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Wilding CS, Cadwell K, Tawn EJ, Relton CL, Taylor GA, Chinnery PF, Turnbull DM. Mitochondrial DNA mutations in individuals occupationally exposed to ionizing radiation. Radiat Res 2006; 165:202-7. [PMID: 16435918 DOI: 10.1667/rr3494.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Mutations in a 443-bp amplicon of the hypervariable region HVR1 of the D-loop of mitochondrial DNA (mtDNA) were quantified in DNA extracted from peripheral blood samples of 10 retired radiation workers who had accumulated external radiation doses of >0.9 Sv over the course of their working life and were compared to the levels of mutations in 10 control individuals matched for age and smoking status. The mutation rate in the 10 exposed individuals was 9.92 x 10(-5) mutations/ nucleotide, and for the controls it was 8.65 x 10(-5) mutations/ nucleotide, with a procedural error rate of 2.65 x 10(-5) mutations/nucleotide. No increase in mtDNA mutations due to radiation exposure was detectable (P = 0.640). In contrast, chromosomal translocation frequencies, a validated radiobiological technique for retrospective dosimetric purposes, were significantly elevated in the exposed individuals. This suggests that mutations identified through sequencing of mtDNA in peripheral blood lymphocytes do not represent a promising genetic marker of DNA damage after low-dose or low-dose-rate exposures to ionizing radiation. There was an increase in singleton mutations above that attributable to procedural error in both exposed and control groups that is likely to reflect age-related somatic mutation.
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Affiliation(s)
- Craig S Wilding
- Genetics Department, Westlakes Research Institute, Moor Row, Cumbria, CA24 3JY, United Kingdom.
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18
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Wilding CS, Trikic MZ, Hingston JL, Copplestone D, Janet Tawn E. Mitochondrial DNA mutation frequencies in experimentally irradiated compost worms, Eisenia fetida. Mutat Res 2006; 603:56-63. [PMID: 16378751 DOI: 10.1016/j.mrgentox.2005.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 10/21/2005] [Accepted: 10/27/2005] [Indexed: 05/05/2023]
Abstract
The compost worm Eisenia fetida is routinely used in ecotoxicological studies. A standard assay to assess genetic damage in this species would be extremely valuable. Since mitochondrial DNA (mtDNA) is known to exhibit an increased mutation rate following exposure to ionising radiation we assessed the validity of a mtDNA-based assay for measuring increases in mutation rate in laboratory-irradiated compost worms. To this end the mutation frequency in the mtDNA of the compost worm E. fetida was quantified following in vivo gamma-irradiation of adult worms in three dose groups. Five adult worms exposed to 1.4 mGy/h for 55 days (total dose 1.85 Gy), five adult worms exposed to 8.5 mGy/h for 55 days (total dose 11.22 Gy) and five adult control worms were used to assess the effect of irradiation on mtDNA mutation induction. DNA samples extracted from irradiated adult worms were used in high-fidelity PCR of a 486 bp region of mtDNA spanning the ATPase 8 gene, chosen for its high spontaneous mutation rate. PCR products were cloned and sequenced to identify mutations, with 89-102 clones successfully sequenced per individual. A significant elevation in mtDNA mutation frequency (p=0.032) was seen in worms exposed at the higher dose rate (8.5 mGy/h, total dose 11.22 Gy; mutation frequency 27.98+/-4.85 x 10(-5)mutations/bp) in comparison to controls (mutation frequency 12.68+/-3.06 x 10(-5)mutations/bp), but no elevation in mutation frequency (p=0.764) was seen for the lower dose rate (1.4 mGy/h, total dose 1.85 Gy; mutation frequency 13.74+/-1.29 x 10(-5)mutations/bp) compared with controls. This indicates that although the technique has the potential to detect an elevation in mutation frequency, it does not have sufficient sensitivity at the doses likely to be encountered in environmental monitoring scenarios.
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Affiliation(s)
- Craig S Wilding
- Genetics Department, Westlakes Research Institute, Moor Row, Cumbria CA24 3JY, UK.
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Abstract
Cells of the thyroid tissue, either diseased or normal, can accumulate altered mitochondrial genomes in primary lesions and in surrounding parenchyma. Depending on the experimental approaches and the extent of the mutational process, it has been possible to demonstrate the occurrence of homoplasmic or heteroplasmic point mutations, presence of a common deletion and random large-scale mtDNA aberrations in various pathological states. Point somatic mutations documented in 5-60% of thyroid tumors do not concentrate in obvious hotspots but tend to cluster in certain regions of the mitochondrial genome and their distribution may differ between carcinomas and controls. Large-scale deletions in mtDNA are quite prevalent in healthy and diseased thyroid; however, the proportion of aberrant mtDNA molecules accounts for a very small part of total mtDNA and does not seem to correlate with pathological characteristics of thyroid tumors. Common deletion is most abundant in Hurthle cell tumors, yet it also occurs in other thyroid diseases as well as in normal tissue. The principal difference between the common deletion and other deletion-type mtDNA molecules is that the former does not depend on the relative mtDNA content in the tissue whereas in a subset of thyroid tumors, such as radiation-associated papillary carcinomas and follicular adenomas, there is a strong correlation between mtDNA levels and prevalence of large-scale deletions. Relative mtDNA levels by themselves are elevated in most thyroid tumors compared to normal tissue. Distinct differential distribution and prevalence of mutational mtDNA burden in normal tissue and thyroid lesions are suggestive of the implication of altered mtDNA in thyroid diseases, especially in cancer.
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Affiliation(s)
- Tatiana Rogounovitch
- Department of Molecular Medicine, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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Chinnery PF, Howel D, Turnbull DM, Johnson MA. Clinical progression of mitochondrial myopathy is associated with the random accumulation of cytochrome c oxidase negative skeletal muscle fibres. J Neurol Sci 2003; 211:63-6. [PMID: 12767499 DOI: 10.1016/s0022-510x(03)00039-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We studied the accumulation of cytochrome c oxidase (COX)-negative skeletal muscle fibres in six patients with a myopathy due to a mitochondrial DNA (mtDNA) defect. Each patient was biopsied on two or more occasions over a period of 3-15 years. Progressive proximal weakness was associated with an increase in the proportion of COX-negative fibres. These fibres were arranged randomly, indicating that each fibre became COX negative independently of the status of neighbouring fibres. The clinical progression of mtDNA myopathy is therefore a consequence of a biochemical defect that develops independently within individual muscle fibres. It is likely that this is due to the clonal expansion of mutant mtDNA.
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Affiliation(s)
- P F Chinnery
- Department of Neurology, The Medical School, The University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
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Tsang WY, Lemire BD. The role of mitochondria in the life of the nematode, Caenorhabditis elegans. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1638:91-105. [PMID: 12853115 DOI: 10.1016/s0925-4439(03)00079-6] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mitochondria are essential organelles involved in energy metabolism via oxidative phosphorylation. They play a vital role in diverse biological processes such as aging and apoptosis. In humans, defects in the mitochondrial respiratory chain (MRC) are responsible for or associated with a bewildering variety of diseases. The nematode Caenorhabditis elegans is a simple animal and a powerful genetic and developmental model system. In this review, we discuss how the nematode model system has contributed to our understanding of mitochondrial dynamics, of the genetics and inheritance of the mitochondrial genome, and of the consequences of nuclear and mitochondrial DNA (mtDNA) mutations. Mitochondrial respiration is vital to energy metabolism but also to other aspects of multicellular life such as aging and development. We anticipate that further significant contributions to our understanding of mitochondrial function in animal biology are forthcoming with the C. elegans model system.
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Affiliation(s)
- William Y Tsang
- Canadian Institutes of Health Research Group in Membrane Protein Research, Department of Biochemistry, University of Alberta, 474 Medical Sciences Bldg., Edmonton, Alberta, Canada T6G 2H7
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Kitagawa K, Takumi S, Nakamura C. Evidence of paternal transmission of mitochondrial DNA in a nucleus-cytoplasm hybrid of timopheevi wheat. Genes Genet Syst 2002; 77:243-50. [PMID: 12419896 DOI: 10.1266/ggs.77.243] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Structural heterogeneity depicted as heteroplasmy of the mitochondrial (mt) transcriptional unit of nad3-orf156 (atp8) was studied in a nucleus-cytoplasm (NC) hybrid of Triticum timopheevi with the D plasmon from the maternal Aegilops squarrosa and compared with that of the parental lines. The tetraploid NC hybrid and the parental lines both showed varying degrees of heteroplasmy in this mtDNA region. The G plasmon of the paternal T. timopheevi possessed five sequence types, while two sequence types were detected in the D plasmon of Ae. squarrosa. The NC hybrid possessed all the five sequence types identical to those of the paternal parent in a 30% relative stochiometry. The remaining 70% comprised only one of the two maternal sequence types, suggestive of strong and selective NC interaction. No novel sequence types were detected and the relative stoichiometries of the paternal sequence types were conserved in the NC hybrid. No paternal-identical or -related sequences were detected in the maternal D plasmon. These results provide evidence of the paternal transmission of the mtDNA and possibly account for the origin of the observed mtDNA heteroplasmy in the NC hybrid.
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Affiliation(s)
- Kazuaki Kitagawa
- Laboratory of Plant Genetics, Department of Biological and Environmental Science, Faculty of Agriculture, and Division of Life Science, Graduate School of Science and Technology, Kobe University, Rokkodai-cho, Nada-ku, Japan
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