1
|
Dubie JJ, Katju V, Bergthorsson U. Dissecting the sequential evolution of a selfish mitochondrial genome in Caenorhabditis elegans. Heredity (Edinb) 2024:10.1038/s41437-024-00704-2. [PMID: 38969772 DOI: 10.1038/s41437-024-00704-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/07/2024] Open
Abstract
Mitochondrial genomes exist in a nested hierarchy of populations where mitochondrial variants are subject to genetic drift and selection at each level of organization, sometimes engendering conflict between different levels of selection, and between the nuclear and mitochondrial genomes. Deletion mutants in the Caenorhabditis elegans mitochondrial genome can reach high intracellular frequencies despite strongly detrimental effects on fitness. During a mutation accumulation (MA) experiment in C. elegans, a 499 bp deletion in ctb-1 rose to 90% frequency within cells while significantly reducing fitness. During the experiment, the deletion-bearing mtDNA acquired three additional mutations in nd5, namely two single insertion frameshift mutations in a homopolymeric run, and a base substitution. Despite an additional fitness cost of these secondary mutations, all deletion-bearing molecules contained the nd5 mutations at the termination of the MA experiment. The presence of mutant mtDNA was associated with increased mtDNA copy-number. Variation in mtDNA copy-number was greater in the MA lines than in a wildtype nuclear background, including a severe reduction in copy-number at one generational timepoint. Evolutionary replay experiments using different generations of the MA experiment as starting points suggests that two of the secondary mutations contribute to the proliferation of the original ctb-1 deletion by unknown mechanisms.
Collapse
Affiliation(s)
- Joseph J Dubie
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Department of Integrative Biology, University of Texas, Austin, TX, USA
| | - Vaishali Katju
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
- Evolutionary Biology, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 752 36, Uppsala, Sweden.
| | - Ulfar Bergthorsson
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
- Evolutionary Biology, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 752 36, Uppsala, Sweden.
| |
Collapse
|
2
|
Gendron EMS, Qing X, Sevigny JL, Li H, Liu Z, Blaxter M, Powers TO, Thomas WK, Porazinska DL. Comparative mitochondrial genomics in Nematoda reveal astonishing variation in compositional biases and substitution rates indicative of multi-level selection. BMC Genomics 2024; 25:615. [PMID: 38890582 PMCID: PMC11184840 DOI: 10.1186/s12864-024-10500-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 06/05/2024] [Indexed: 06/20/2024] Open
Abstract
BACKGROUND Nematodes are the most abundant and diverse metazoans on Earth, and are known to significantly affect ecosystem functioning. A better understanding of their biology and ecology, including potential adaptations to diverse habitats and lifestyles, is key to understanding their response to global change scenarios. Mitochondrial genomes offer high species level characterization, low cost of sequencing, and an ease of data handling that can provide insights into nematode evolutionary pressures. RESULTS Generally, nematode mitochondrial genomes exhibited similar structural characteristics (e.g., gene size and GC content), but displayed remarkable variability around these general patterns. Compositional strand biases showed strong codon position specific G skews and relationships with nematode life traits (especially parasitic feeding habits) equal to or greater than with predicted phylogeny. On average, nematode mitochondrial genomes showed low non-synonymous substitution rates, but also high clade specific deviations from these means. Despite the presence of significant mutational saturation, non-synonymous (dN) and synonymous (dS) substitution rates could still be significantly explained by feeding habit and/or habitat. Low ratios of dN:dS rates, particularly associated with the parasitic lifestyles, suggested the presence of strong purifying selection. CONCLUSIONS Nematode mitochondrial genomes demonstrated a capacity to accumulate diversity in composition, structure, and content while still maintaining functional genes. Moreover, they demonstrated a capacity for rapid evolutionary change pointing to a potential interaction between multi-level selection pressures and rapid evolution. In conclusion, this study helps establish a background for our understanding of the potential evolutionary pressures shaping nematode mitochondrial genomes, while outlining likely routes of future inquiry.
Collapse
Affiliation(s)
- Eli M S Gendron
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA.
| | - Xue Qing
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.
| | - Joseph L Sevigny
- Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA
- Hubbard Center for Genome Studies, University of New Hampshire, Durham, NH, USA
| | - Hongmei Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
| | - Zhiyin Liu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
| | | | - Thomas O Powers
- Department of Plant Pathology, University of Nebraska, Lincoln, NE, USA
| | - W Kelly Thomas
- Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA
- Hubbard Center for Genome Studies, University of New Hampshire, Durham, NH, USA
| | - Dorota L Porazinska
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| |
Collapse
|
3
|
Sequeira AN, O’Keefe IP, Katju V, Bergthorsson U. Friend turned foe: selfish behavior of a spontaneously arising mitochondrial deletion in an experimentally evolved Caenorhabditis elegans population. G3 (BETHESDA, MD.) 2024; 14:jkae018. [PMID: 38261394 PMCID: PMC11090458 DOI: 10.1093/g3journal/jkae018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 01/24/2024]
Abstract
Selfish mitochondrial DNA (mtDNA) mutations are variants that can proliferate within cells and enjoy a replication or transmission bias without fitness benefits for the host. mtDNA deletions in Caenorhabditis elegans can reach high heteroplasmic frequencies despite significantly reducing fitness, illustrating how new mtDNA variants can give rise to genetic conflict between different levels of selection and between the nuclear and mitochondrial genomes. During a mutation accumulation experiment in C. elegans, a 1,034-bp deletion originated spontaneously and reached an 81.7% frequency within an experimental evolution line. This heteroplasmic mtDNA deletion, designated as meuDf1, eliminated portions of 2 protein-coding genes (coxIII and nd4) and tRNA-thr in entirety. mtDNA copy number in meuDf1 heteroplasmic individuals was 35% higher than in individuals with wild-type mitochondria. After backcrossing into a common genetic background, the meuDf1 mitotype was associated with reduction in several fitness traits and independent competition experiments found a 40% reduction in composite fitness. Experiments that relaxed individual selection by single individual bottlenecks demonstrated that the deletion-bearing mtDNA possessed a strong transmission bias, thereby qualifying it as a novel selfish mitotype.
Collapse
Affiliation(s)
- Abigail N Sequeira
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
- Department of Biology, Pennsylvania State University, 208 Mueller Laboratory, University Park, PA 16802, USA
| | - Ian P O’Keefe
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
- Department of Biochemistry and Molecular Biology, University of Maryland, 655 W. Baltimore Street, Baltimore, MD 21201, USA
| | - Vaishali Katju
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
- Program in Evolutionary Biology, Department of Ecology and Genetics (IEG), Evolutionsbiologiskt centrum, Norbyvägen 18D, Uppsala University, 752 36 Uppsala, Sweden
| | - Ulfar Bergthorsson
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
- Program in Evolutionary Biology, Department of Ecology and Genetics (IEG), Evolutionsbiologiskt centrum, Norbyvägen 18D, Uppsala University, 752 36 Uppsala, Sweden
| |
Collapse
|
4
|
Biró B, Gál Z, Fekete Z, Klecska E, Hoffmann OI. Mitochondrial genome plasticity of mammalian species. BMC Genomics 2024; 25:278. [PMID: 38486136 PMCID: PMC10941376 DOI: 10.1186/s12864-024-10201-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 03/08/2024] [Indexed: 03/17/2024] Open
Abstract
There is an ongoing process in which mitochondrial sequences are being integrated into the nuclear genome. The importance of these sequences has already been revealed in cancer biology, forensic, phylogenetic studies and in the evolution of the eukaryotic genetic information. Human and numerous model organisms' genomes were described from those sequences point of view. Furthermore, recent studies were published on the patterns of these nuclear localised mitochondrial sequences in different taxa.However, the results of the previously released studies are difficult to compare due to the lack of standardised methods and/or using few numbers of genomes. Therefore, in this paper our primary goal is to establish a uniform mining pipeline to explore these nuclear localised mitochondrial sequences.Our results show that the frequency of several repetitive elements is higher in the flanking regions of these sequences than expected. A machine learning model reveals that the flanking regions' repetitive elements and different structural characteristics are highly influential during the integration process.In this paper, we introduce a general mining pipeline for all mammalian genomes. The workflow is publicly available and is believed to serve as a validated baseline for future research in this field. We confirm the widespread opinion, on - as to our current knowledge - the largest dataset, that structural circumstances and events corresponding to repetitive elements are highly significant. An accurate model has also been trained to predict these sequences and their corresponding flanking regions.
Collapse
Affiliation(s)
- Bálint Biró
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary.
- Group BM, Data Insights Team, _VOIS, Kerepesi str. 35, 1087, Budapest, Hungary.
| | - Zoltán Gál
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary
| | - Zsófia Fekete
- Department of Genetics and Genomics, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary
| | - Eszter Klecska
- FamiCord Group, Krio Institute, Kelemen László str, 1026, Budapest, Hungary
| | - Orsolya Ivett Hoffmann
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary.
| |
Collapse
|
5
|
Nuryadi H, Mandagi IF, Masengi KWA, Kusumi J, Inomata N, Yamahira K. Evidence for hybridization-driven heteroplasmy maintained across generations in a ricefish endemic to a Wallacean ancient lake. Biol Lett 2024; 20:20230385. [PMID: 38503345 PMCID: PMC10950462 DOI: 10.1098/rsbl.2023.0385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 02/27/2024] [Indexed: 03/21/2024] Open
Abstract
Heteroplasmy, the presence of multiple mitochondrial DNA (mtDNA) haplotypes within cells of an individual, is caused by mutation or paternal leakage. However, heteroplasmy is usually resolved to homoplasmy within a few generations because of germ-line bottlenecks; therefore, instances of heteroplasmy are limited in nature. Here, we report heteroplasmy in the ricefish species Oryzias matanensis, endemic to Lake Matano, an ancient lake in Sulawesi Island, in which one individual was known to have many heterozygous sites in the mitochondrial NADH dehydrogenase subunit 2 (ND2) gene. In this study, we cloned the ND2 gene for some additional individuals with heterozygous sites and demonstrated that they are truly heteroplasmic. Phylogenetic analysis revealed that the extra haplotype within the heteroplasmic O. matanensis individuals clustered with haplotypes of O. marmoratus, a congeneric species inhabiting adjacent lakes. This indicated that the heteroplasmy originated from paternal leakage due to interspecific hybridization. The extra haplotype was unique and contained two non-synonymous substitutions. These findings demonstrate that this hybridization-driven heteroplasmy was maintained across generations for a long time to the extent that the extra mitochondria evolved within the new host.
Collapse
Affiliation(s)
- Handung Nuryadi
- Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, Japan
| | - Ixchel F. Mandagi
- Faculty of Fisheries and Marine Science, Sam Ratulangi University, Manado, Indonesia
| | | | - Junko Kusumi
- Faculty of Social and Cultural Studies, Kyushu University, Fukuoka, Japan
| | - Nobuyuki Inomata
- Department of Environmental Science, Fukuoka Women's University, Fukuoka, Japan
| | - Kazunori Yamahira
- Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, Japan
| |
Collapse
|
6
|
Sun KK, Ding Y, Chen L, Sun JT. A Comparative Analysis of Selection Pressures Suffered by Mitochondrial Genomes in Two Planthopper Species with Divergent Climate Distributions. Int J Mol Sci 2023; 24:16847. [PMID: 38069176 PMCID: PMC10706623 DOI: 10.3390/ijms242316847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 11/23/2023] [Accepted: 11/25/2023] [Indexed: 12/18/2023] Open
Abstract
Mitochondrial DNA (mtDNA) has been widely used as a valuable tool in studies related to evolution and population genetics, under the implicit assumption of neutral evolution. However, recent studies suggest that natural selection also plays a significant role in shaping mitochondrial genome evolution, although the specific driving forces remain elusive. In this study, we aimed to investigate whether and how climate influences mitochondrial genome evolution by comparing the selection pressures acting on mitochondrial genomes between two rice planthoppers, Sogatella furcifera (Horváth) and Laodelphax striatellus (Fallén), which have different climate distributions. We employed the dN/dS method, MK test and Tajima's D tests for our analysis. Our results showed that the mitochondrial genomes of the two species appear to undergo predominantly purifying selection, consistent with the nearly neutral evolution model. However, we observed varied degrees of purifying selection among the 13 protein-coding genes. Notably, ND1, ND2, ND6, COIII, and ATP8 exhibited significantly stronger purifying selection and greater divergence between the two species compared to the other genes. Additionally, we observed relatively stronger purifying selection in the mitochondrial genomes of S. furcifera compared to L. striatellus. This difference could be attributed to varying metabolic requirements arising from distinct habitats or other factors that are unclear here. Furthermore, we speculate that mito-nuclear epistatic interactions may play a role in maintaining nonsynonymous polymorphisms, particularly for COI and COII. Overall, our results shed some light on the influence of climate on mitochondrial genome evolution.
Collapse
Affiliation(s)
| | | | | | - Jing-Tao Sun
- Department of Entomology, Nanjing Agricultural University, Nanjing 210095, China; (K.-K.S.); (Y.D.)
| |
Collapse
|
7
|
Estes S, Dietz ZP, Katju V, Bergthorsson U. Evolutionary codependency: insights into the mitonuclear interaction landscape from experimental and wild Caenorhabditis nematodes. Curr Opin Genet Dev 2023; 81:102081. [PMID: 37421904 DOI: 10.1016/j.gde.2023.102081] [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: 03/06/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 07/10/2023]
Abstract
Aided by new technologies, the upsurgence of research into mitochondrial genome biology during the past 15 years suggests that we have misunderstood, and perhaps dramatically underestimated, the ongoing biological and evolutionary significance of our long-time symbiotic partner. While we have begun to scratch the surface of several topics, many questions regarding the nature of mutation and selection in the mitochondrial genome, and the nature of its relationship to the nuclear genome, remain unanswered. Although best known for their contributions to studies of developmental and aging biology, Caenorhabditis nematodes are increasingly recognized as excellent model systems to advance understanding in these areas. We review recent discoveries with relevance to mitonuclear coevolution and conflict and offer several fertile areas for future work.
Collapse
Affiliation(s)
- Suzanne Estes
- Portland State University, Department of Biology, Portland, OR, USA.
| | - Zachary P Dietz
- Portland State University, Department of Biology, Portland, OR, USA
| | - Vaishali Katju
- Uppsala University, Department of Ecology and Genetics, 752 36 Uppsala, Sweden
| | - Ulfar Bergthorsson
- Uppsala University, Department of Ecology and Genetics, 752 36 Uppsala, Sweden
| |
Collapse
|
8
|
Velazco-Cruz L, Ross JA. Genetic architecture and temporal analysis of Caenorhabditis briggsae hybrid developmental delay. PLoS One 2022; 17:e0272843. [PMID: 35951524 PMCID: PMC9371335 DOI: 10.1371/journal.pone.0272843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/27/2022] [Indexed: 11/18/2022] Open
Abstract
Identifying the alleles that reduce hybrid fitness is a major goal in the study of speciation genetics. It is rare to identify systems in which hybrid incompatibilities with minor phenotypic effects are segregating in genetically diverse populations of the same biological species. Such traits do not themselves cause reproductive isolation but might initiate the process. In the nematode Caenorhabditis briggsae, a small percent of F2 generation hybrids between two natural populations suffer from developmental delay, in which adulthood is reached after approximately 33% more time than their wild-type siblings. Prior efforts to identify the genetic basis for this hybrid incompatibility assessed linkage using one or two genetic markers on chromosome III and suggested that delay is caused by a toxin-antidote element. Here, we have genotyped F2 hybrids using multiple chromosome III markers to refine the developmental delay locus. Also, to better define the developmental delay phenotype, we measured the development rate of 66 F2 hybrids and found that delay is not restricted to a particular larval developmental stage. Deviation of the developmental delay frequency from hypothetical expectations for a toxin-antidote element adds support to the assertion that the epistatic interaction is not fully penetrant. Our mapping and refinement of the delay phenotype motivates future efforts to study the genetic architecture of hybrid dysfunction between genetically distinct populations of one species by identifying the underlying loci.
Collapse
Affiliation(s)
- Leonardo Velazco-Cruz
- Department of Biology, California State University, Fresno, California, United States of America
| | - Joseph A. Ross
- Department of Biology, California State University, Fresno, California, United States of America
- * E-mail:
| |
Collapse
|
9
|
Ní Leathlobhair M, Lenski RE. Population genetics of clonally transmissible cancers. Nat Ecol Evol 2022; 6:1077-1089. [PMID: 35879542 DOI: 10.1038/s41559-022-01790-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 05/12/2022] [Indexed: 11/08/2022]
Abstract
Populations of cancer cells are subject to the same core evolutionary processes as asexually reproducing, unicellular organisms. Transmissible cancers are particularly striking examples of these processes. These unusual cancers are clonal lineages that can spread through populations via physical transfer of living cancer cells from one host individual to another, and they have achieved long-term success in the colonization of at least eight different host species. Population genetic theory provides a useful framework for understanding the shift from a multicellular sexual animal into a unicellular asexual clone and its long-term effects on the genomes of these cancers. In this Review, we consider recent findings from transmissible cancer research with the goals of developing an evolutionarily informed perspective on transmissible cancers, examining possible implications for their long-term fate and identifying areas for future research on these exceptional lineages.
Collapse
Affiliation(s)
- Máire Ní Leathlobhair
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK.
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland.
| | - Richard E Lenski
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, USA
| |
Collapse
|
10
|
Biró B, Gál Z, Schiavo G, Ribari A, Joe Utzeri V, Brookman M, Fontanesi L, Hoffmann OI. Nuclear mitochondrial DNA sequences in the rabbit genome. Mitochondrion 2022; 66:1-6. [PMID: 35842180 DOI: 10.1016/j.mito.2022.07.003] [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: 03/24/2022] [Revised: 05/23/2022] [Accepted: 07/10/2022] [Indexed: 10/17/2022]
Abstract
Numtogenesis is observable in the mammalian genomes resulting in the integration of mitochondrial segments into the nuclear genomes (numts). To identify numts in rabbit, we aligned mitochondrial and nuclear genomes. Alignment significance threshold was calculated and individual characteristics of numts were analysed. We found 153 numts in the nuclear genome. The GC content of numts were significantly lower than the GC content of their genomic flanking regions or the genome itself. The frequency of three mammalian-wide interspersed repeats were increased in the proximity of numts. The decreased GC content around numts strengthen the theory which supposes a link between DNA structural instability and numt integration.
Collapse
Affiliation(s)
- Bálint Biró
- Hungarian University of Agricultural and Life Sciences, Institute of Genetics and Biotechnology, Szent-Györgyi Albert Str. 4, H-2100, Gödöllö, Hungary
| | - Zoltán Gál
- Hungarian University of Agricultural and Life Sciences, Institute of Genetics and Biotechnology, Szent-Györgyi Albert Str. 4, H-2100, Gödöllö, Hungary
| | - Giuseppina Schiavo
- University of Bologna, Department of Agricultural and Food Sciences, Division of Animal Sciences, Viale Fanin 46, 40127 Bologna, Italy
| | - Anisa Ribari
- University of Bologna, Department of Agricultural and Food Sciences, Division of Animal Sciences, Viale Fanin 46, 40127 Bologna, Italy
| | - Valerio Joe Utzeri
- University of Bologna, Department of Agricultural and Food Sciences, Division of Animal Sciences, Viale Fanin 46, 40127 Bologna, Italy
| | - Michael Brookman
- Hanze University of Applied Sciences, Department for Biology and Medical Laboratory Research, Zernikeplein 7, 9747 AS Groningen, Netherlands
| | - Luca Fontanesi
- University of Bologna, Department of Agricultural and Food Sciences, Division of Animal Sciences, Viale Fanin 46, 40127 Bologna, Italy
| | - Orsolya Ivett Hoffmann
- Hungarian University of Agricultural and Life Sciences, Institute of Genetics and Biotechnology, Szent-Györgyi Albert Str. 4, H-2100, Gödöllö, Hungary.
| |
Collapse
|
11
|
Perez M, Breusing C, Angers B, Beinart RA, Won YJ, Young CR. Divergent paths in the evolutionary history of maternally transmitted clam symbionts. Proc Biol Sci 2022; 289:20212137. [PMID: 35259985 PMCID: PMC8905170 DOI: 10.1098/rspb.2021.2137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Vertical transmission of bacterial endosymbionts is accompanied by virtually irreversible gene loss that results in a progressive reduction in genome size. While the evolutionary processes of genome reduction have been well described in some terrestrial symbioses, they are less understood in marine systems where vertical transmission is rarely observed. The association between deep-sea vesicomyid clams and chemosynthetic Gammaproteobacteria is one example of maternally inherited symbioses in the ocean. Here, we assessed the contributions of drift, recombination and selection to genome evolution in two extant vesicomyid symbiont clades by comparing 15 representative symbiont genomes (1.017-1.586 Mb) to those of closely related bacteria and the hosts' mitochondria. Our analyses suggest that drift is a significant force driving genome evolution in vesicomyid symbionts, though selection and interspecific recombination appear to be critical for maintaining symbiont functional integrity and creating divergent patterns of gene conservation. Notably, the two symbiont clades possess putative functional differences in sulfide physiology, anaerobic respiration and dependency on environmental vitamin B12, which probably reflect adaptations to different ecological habitats available to each symbiont group. Overall, these results contribute to our understanding of the eco-evolutionary processes shaping reductive genome evolution in vertically transmitted symbioses.
Collapse
Affiliation(s)
- Maëva Perez
- Department of Biological Sciences, Université de Montréal, Montreal, Canada
| | - Corinna Breusing
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | - Bernard Angers
- Department of Biological Sciences, Université de Montréal, Montreal, Canada
| | - Roxanne A Beinart
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | - Yong-Jin Won
- Division of EcoScience, Ewha Womans University, Seoul, South Korea
| | | |
Collapse
|
12
|
Erić P, Patenković A, Erić K, Tanasković M, Davidović S, Rakić M, Savić Veselinović M, Stamenković-Radak M, Jelić M. Temperature-Specific and Sex-Specific Fitness Effects of Sympatric Mitochondrial and Mito-Nuclear Variation in Drosophila obscura. INSECTS 2022; 13:insects13020139. [PMID: 35206713 PMCID: PMC8880146 DOI: 10.3390/insects13020139] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/20/2022] [Accepted: 01/22/2022] [Indexed: 12/28/2022]
Abstract
Simple Summary Does variation in the mitochondrial DNA sequence influence the survival and reproduction of an individual? What is the purpose of genetic variation of the mitochondrial DNA between individuals from the same population? As a simple laboratory model, Drosophila species can give us the answer to this question. Creating experimental lines with different combinations of mitochondrial and nuclear genomic DNA and testing how successful these lines were in surviving in different experimental set-ups enables us to deduce the effect that both genomes have on fitness. This study on D. obscura experimentally validates theoretical models that explain the persistence of mitochondrial DNA variation within populations. Our results shed light on the various mechanisms that maintain this type of variation. Finally, by conducting the experiments on two experimental temperatures, we have shown that environmental variations can support mitochondrial DNA variation within populations. Abstract The adaptive significance of sympatric mitochondrial (mtDNA) variation and the role of selective mechanisms that maintain it are debated to this day. Isofemale lines of Drosophila obscura collected from four populations were backcrossed within populations to construct experimental lines, with all combinations of mtDNA Cyt b haplotypes and nuclear genetic backgrounds (nuDNA). Individuals of both sexes from these lines were then subjected to four fitness assays (desiccation resistance, developmental time, egg-to-adult viability and sex ratio) on two experimental temperatures to examine the role of temperature fluctuations and sex-specific selection, as well as the part that interactions between the two genomes play in shaping mtDNA variation. The results varied across populations and fitness components. In the majority of comparisons, they show that sympatric mitochondrial variants affect fitness. However, their effect should be examined in light of interactions with nuDNA, as mito-nuclear genotype was even more influential on fitness across all components. We found both sex-specific and temperature-specific differences in mitochondrial and mito-nuclear genotype ranks in all fitness components. The effect of temperature-specific selection was found to be more prominent, especially in desiccation resistance. From the results of different components tested, we can also infer that temperature-specific mito-nuclear interactions rather than sex-specific selection on mito-nuclear genotypes have a more substantial role in preserving mtDNA variation in this model species.
Collapse
Affiliation(s)
- Pavle Erić
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
- Correspondence: ; Tel.: +381-112-078-334
| | - Aleksandra Patenković
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Katarina Erić
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Marija Tanasković
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Slobodan Davidović
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Mina Rakić
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| | - Marija Savić Veselinović
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| | - Marina Stamenković-Radak
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| | - Mihailo Jelić
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| |
Collapse
|
13
|
Zhang H, Esposito M, Pezet MG, Aryaman J, Wei W, Klimm F, Calabrese C, Burr SP, Macabelli CH, Viscomi C, Saitou M, Chiaratti MR, Stewart JB, Jones N, Chinnery PF. Mitochondrial DNA heteroplasmy is modulated during oocyte development propagating mutation transmission. SCIENCE ADVANCES 2021; 7:eabi5657. [PMID: 34878831 PMCID: PMC8654302 DOI: 10.1126/sciadv.abi5657] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 10/15/2021] [Indexed: 05/02/2023]
Abstract
Heteroplasmic mitochondrial DNA (mtDNA) mutations are a common cause of inherited disease, but a few recurrent mutations account for the vast majority of new families. The reasons for this are not known. We studied heteroplasmic mice transmitting m.5024C>T corresponding to a human pathogenic mutation. Analyzing 1167 mother-pup pairs, we show that m.5024C>T is preferentially transmitted from low to higher levels but does not reach homoplasmy. Single-cell analysis of the developing mouse oocytes showed the preferential increase in mutant over wild-type mtDNA in the absence of cell division. A similar inheritance pattern is seen in human pedigrees transmitting several pathogenic mtDNA mutations. In m.5024C>T mice, this can be explained by the preferential propagation of mtDNA during oocyte maturation, counterbalanced by purifying selection against high heteroplasmy levels. This could explain how a disadvantageous mutation in a carrier increases to levels that cause disease but fails to fixate, causing multigenerational heteroplasmic mtDNA disorders.
Collapse
Affiliation(s)
- Haixin Zhang
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Marco Esposito
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
- Leverhulme Centre for Cellular Bionics, Imperial College, London, UK
| | - Mikael G. Pezet
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Juvid Aryaman
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
| | - Wei Wei
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Florian Klimm
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
| | - Claudia Calabrese
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Stephen P. Burr
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Carolina H. Macabelli
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos 13565-905, Brazil
| | - Carlo Viscomi
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Mitinori Saitou
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
- JST, ERATO, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Marcos R. Chiaratti
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos 13565-905, Brazil
| | - James B. Stewart
- Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
- Biosciences Institute, Faculty of Medical Sciences, Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, UK
| | - Nick Jones
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
- Leverhulme Centre for Cellular Bionics, Imperial College, London, UK
| | - Patrick F. Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| |
Collapse
|
14
|
Comparative mitogenomics of Spirocerca lupi from South Africa and China: Variation and possible heteroplasmy. Vet Parasitol 2021; 300:109595. [PMID: 34678674 DOI: 10.1016/j.vetpar.2021.109595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 11/21/2022]
Abstract
The complete mitochondrial genome of Spirocerca lupi isolated from a dog in South Africa was sequenced using next generation sequencing (NGS) technology and the 12 protein coding genes along with the two rRNA genes were compared to 18 other nematode species as well as S. lupi from China. The mitochondrial genome of S. lupi South Africa had a mean genetic diversity of 6.1 % compared to S. lupi China with some variation in nucleotide composition, gene positioning and size. Pairwise distance results indicated slightly higher variation when compared to the pairwise distances of other closely related species, however, this variation was not high enough for it to be considered a cryptic species. Phylogenetic analysis indicated that S. lupi from the two continents are very similar. In addition, single nucleotide polymorphisms were detected in the nad2 gene with ten sequence variants identified from 10 clones from a single nematode, suggesting possible heteroplasmy. The origin of the heteroplasmy is currently unknown but it is speculated to have arisen from accumulated mutations in the mitochondria during somatic replication.
Collapse
|
15
|
Dutta A, Dutreux F, Schacherer J. Loss of heterozygosity results in rapid but variable genome homogenization across yeast genetic backgrounds. eLife 2021; 10:70339. [PMID: 34159898 PMCID: PMC8245132 DOI: 10.7554/elife.70339] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/11/2021] [Indexed: 12/12/2022] Open
Abstract
The dynamics and diversity of the appearance of genetic variants play an essential role in the evolution of the genome and the shaping of biodiversity. Recent population-wide genome sequencing surveys have highlighted the importance of loss of heterozygosity (LOH) events and have shown that they are a neglected part of the genetic diversity landscape. To assess the extent, variability, and spectrum, we explored the accumulation of LOH events in 169 heterozygous diploid Saccharomyces cerevisiae mutation accumulation lines across nine genetic backgrounds. In total, we detected a large set of 22,828 LOH events across distinct genetic backgrounds with a heterozygous level ranging from 0.1% to 1%. LOH events are very frequent with a rate consistently much higher than the mutation rate, showing their importance for genome evolution. We observed that the interstitial LOH (I-LOH) events, resulting in internal short LOH tracts, were much frequent (n = 19,660) than the terminal LOH (T-LOH) events, that is, tracts extending to the end of the chromosome (n = 3168). However, the spectrum, the rate, and the fraction of the genome under LOH vary across genetic backgrounds. Interestingly, we observed that the more the ancestors were heterozygous, the more they accumulated T-LOH events. In addition, frequent short I-LOH tracts are a signature of the lines derived from hybrids with low spore fertility. Finally, we found lines showing almost complete homozygotization during vegetative progression. Overall, our results highlight that the variable dynamics of the LOH accumulation across distinct genetic backgrounds might lead to rapid differential genome evolution during vegetative growth.
Collapse
Affiliation(s)
- Abhishek Dutta
- Université de Strasbourg, CNRS, GMGM UMR 7156, Strasbourg, France
| | - Fabien Dutreux
- Université de Strasbourg, CNRS, GMGM UMR 7156, Strasbourg, France
| | - Joseph Schacherer
- Université de Strasbourg, CNRS, GMGM UMR 7156, Strasbourg, France.,Institut Universitaire de France (IUF), Paris, France
| |
Collapse
|
16
|
Jeedigunta SP, Minenkova AV, Palozzi JM, Hurd TR. Avoiding Extinction: Recent Advances in Understanding Mechanisms of Mitochondrial DNA Purifying Selection in the Germline. Annu Rev Genomics Hum Genet 2021; 22:55-80. [PMID: 34038145 DOI: 10.1146/annurev-genom-121420-081805] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondria are unusual organelles in that they contain their own genomes, which are kept apart from the rest of the DNA in the cell. While mitochondrial DNA (mtDNA) is essential for respiration and most multicellular life, maintaining a genome outside the nucleus brings with it a number of challenges. Chief among these is preserving mtDNA genomic integrity from one generation to the next. In this review, we discuss what is known about negative (purifying) selection mechanisms that prevent deleterious mutations from accumulating in mtDNA in the germline. Throughout, we focus on the female germline, as it is the tissue through which mtDNA is inherited in most organisms and, therefore, the tissue that most profoundly shapes the genome. We discuss recent progress in uncovering the mechanisms of germline mtDNA selection, from humans to invertebrates.
Collapse
Affiliation(s)
- Swathi P Jeedigunta
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada;
| | - Anastasia V Minenkova
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada;
| | - Jonathan M Palozzi
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada;
| | - Thomas R Hurd
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada;
| |
Collapse
|
17
|
Howe DK, Ha AD, Colton A, De Ley IT, Rae RG, Ross J, Wilson M, Nermut J, Zhao Z, Mc Donnell RJ, Denver DR. Phylogenetic evidence for the invasion of a commercialized European Phasmarhabditis hermaphrodita lineage into North America and New Zealand. PLoS One 2020; 15:e0237249. [PMID: 32804938 PMCID: PMC7430733 DOI: 10.1371/journal.pone.0237249] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 07/22/2020] [Indexed: 11/24/2022] Open
Abstract
Biological control (biocontrol) as a component of pest management strategies reduces reliance on synthetic chemicals, and seemingly offers a natural approach that minimizes environmental impact. However, introducing a new organism to new environments as a classical biocontrol agent can have broad and unanticipated biodiversity effects and conservation consequences. Nematodes are currently used in a variety of commercial biocontrol applications, including the use of Phasmarhabditis hermaphrodita as an agent targeting pest slug and snail species. This species was originally discovered in Germany, and is generally thought to have European origins. P. hermaphrodita is sold under the trade name Nemaslug®, and is available only in European markets. However, this nematode species was discovered in New Zealand and the western United States, though its specific origins remained unclear. In this study, we analyzed 45 nematode strains representing eight different Phasmarhabditis species, collected from nine countries around the world. A segment of nematode mitochondrial DNA (mtDNA) was sequenced and subjected to phylogenetic analyses. Our mtDNA phylogenies were overall consistent with previous analyses based on nuclear ribosomal RNA (rRNA) loci. The recently discovered P. hermaphrodita strains in New Zealand and the United States had mtDNA haplotypes nearly identical to that of Nemaslug®, and these were placed together in an intraspecific monophyletic clade with high support in maximum likelihood and Bayesian analyses. We also examined bacteria that co-cultured with the nematode strains isolated in Oregon, USA, by analyzing 16S rRNA sequences. Eight different bacterial genera were found to associate with these nematodes, though Moraxella osloensis, the bacteria species used in the Nemaslug® formulation, was not detected. This study provided evidence that nematodes deriving from the Nemaslug® biocontrol product have invaded countries where its use is prohibited by regulatory agencies and not commercially available.
Collapse
Affiliation(s)
- Dana K. Howe
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - Anh D. Ha
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Andrew Colton
- Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America
| | - Irma Tandingan De Ley
- Department of Nematology, University of California-Riverside, Riverside, California, United States of America
| | - Robbie G. Rae
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Jenna Ross
- Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University, Matieland, South Africa
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Crop Health and Protection (CHAP), National Agri-Food Innovation Campus, Sand Hutton, York, United Kingdom
| | - Michael Wilson
- Independent Researcher/Consultant, Hamilton, New Zealand
| | - Jiří Nermut
- Biology Centre CAS, Institute of Entomology, Branišovská, České Budějovice, Czech Republic
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Rory J. Mc Donnell
- Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America
| | - Dee R. Denver
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| |
Collapse
|
18
|
Kočí J, Röslein J, Pačes J, Kotusz J, Halačka K, Koščo J, Fedorčák J, Iakovenko N, Janko K. No evidence for accumulation of deleterious mutations and fitness degradation in clonal fish hybrids: Abandoning sex without regrets. Mol Ecol 2020; 29:3038-3055. [PMID: 32627290 PMCID: PMC7540418 DOI: 10.1111/mec.15539] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/18/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023]
Abstract
Despite its inherent costs, sexual reproduction is ubiquitous in nature, and the mechanisms to protect it from a competitive displacement by asexuality remain unclear. Popular mutation-based explanations, like the Muller's ratchet and the Kondrashov's hatchet, assume that purifying selection may not halt the accumulation of deleterious mutations in the nonrecombining genomes, ultimately leading to their degeneration. However, empirical evidence is scarce and it remains particularly unclear whether mutational degradation proceeds fast enough to ensure the decay of clonal organisms and to prevent them from outcompeting their sexual counterparts. To test this hypothesis, we jointly analysed the exome sequences and the fitness-related phenotypic traits of the sexually reproducing fish species and their clonal hybrids, whose evolutionary ages ranged from F1 generations to 300 ky. As expected, mutations tended to accumulate in the clonal genomes in a time-dependent manner. However, contrary to the predictions, we found no trend towards increased nonsynonymity of mutations acquired by clones, nor higher radicality of their amino acid substitutions. Moreover, there was no evidence for fitness degeneration in the old clones compared with that in the younger ones. In summary, although an efficacy of purifying selection may still be reduced in the asexual genomes, our data indicate that its efficiency is not drastically decreased. Even the oldest investigated clone was found to be too young to suffer fitness consequences from a mutation accumulation. This suggests that mechanisms other than mutation accumulation may be needed to explain the competitive advantage of sex in the short term.
Collapse
Affiliation(s)
- Jan Kočí
- Department of Biology and Ecology, University of Ostrava, Ostrava, Czechia.,Institute of Animal Physiology and Genetics, Czech Academy of Science, Liběchov, Czechia
| | - Jan Röslein
- Department of Biology and Ecology, University of Ostrava, Ostrava, Czechia.,Institute of Animal Physiology and Genetics, Czech Academy of Science, Liběchov, Czechia
| | - Jan Pačes
- Institute of Animal Physiology and Genetics, Czech Academy of Science, Liběchov, Czechia.,Institute of Molecular Genetics, Czech Academy of Science, Prague, Czechia
| | - Jan Kotusz
- Museum of Natural History, University of Wrocław, Wrocław, Poland
| | - Karel Halačka
- Institute of Vertebrate Biology, Czech Academy of Science, Brno, Czechia
| | - Ján Koščo
- Department of Ecology, University of Prešov, Prešov, Slovakia
| | - Jakub Fedorčák
- Department of Ecology, University of Prešov, Prešov, Slovakia
| | - Nataliia Iakovenko
- Department of Biology and Ecology, University of Ostrava, Ostrava, Czechia.,Institute of Animal Physiology and Genetics, Czech Academy of Science, Liběchov, Czechia
| | - Karel Janko
- Department of Biology and Ecology, University of Ostrava, Ostrava, Czechia.,Institute of Animal Physiology and Genetics, Czech Academy of Science, Liběchov, Czechia
| |
Collapse
|
19
|
Thompson KA. Experimental Hybridization Studies Suggest That Pleiotropic Alleles Commonly Underlie Adaptive Divergence between Natural Populations. Am Nat 2020; 196:E16-E22. [PMID: 32552104 DOI: 10.1086/708722] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The alleles used for adaptation can pleiotropically affect traits under stabilizing selection. The fixation of alleles with deleterious pleiotropic side effects causes compensatory alleles to be favored by selection. Such compensatory alleles might segregate in interpopulation hybrids, resulting in segregation variance for traits where parents have indistinguishable phenotypes. If adaptation typically involves pleiotropy and compensation, then the segregation variance for traits under stabilizing selection is expected to increase with the magnitude of adaptive phenotypic divergence between parents. This prediction has not been tested empirically, and I gathered data from experimental hybridization studies to evaluate it. I found that pairs of parents that are more phenotypically divergent beget hybrids with more segregation variance in traits for which the parents are statistically indistinguishable. This result suggests that adaptive divergence between pairs of natural populations proceeds via pleiotropy and compensation and that deleterious transgressive segregation variance accumulates systematically as populations diverge.
Collapse
|
20
|
Klucnika A, Ma H. A battle for transmission: the cooperative and selfish animal mitochondrial genomes. Open Biol 2020; 9:180267. [PMID: 30890027 PMCID: PMC6451365 DOI: 10.1098/rsob.180267] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial genome is an evolutionarily persistent and cooperative component of metazoan cells that contributes to energy production and many other cellular processes. Despite sharing the same host as the nuclear genome, the multi-copy mitochondrial DNA (mtDNA) follows very different rules of replication and transmission, which translate into differences in the patterns of selection. On one hand, mtDNA is dependent on the host for its transmission, so selections would favour genomes that boost organismal fitness. On the other hand, genetic heterogeneity within an individual allows different mitochondrial genomes to compete for transmission. This intra-organismal competition could select for the best replicator, which does not necessarily give the fittest organisms, resulting in mito-nuclear conflict. In this review, we discuss the recent advances in our understanding of the mechanisms and opposing forces governing mtDNA transmission and selection in bilaterians, and what the implications of these are for mtDNA evolution and mitochondrial replacement therapy.
Collapse
Affiliation(s)
- Anna Klucnika
- 1 Wellcome Trust/Cancer Research UK Gurdon Institute , Tennis Court Road, Cambridge CB2 1QN , UK.,2 Department of Genetics, University of Cambridge , Downing Street, Cambridge CB2 3EH , UK
| | - Hansong Ma
- 1 Wellcome Trust/Cancer Research UK Gurdon Institute , Tennis Court Road, Cambridge CB2 1QN , UK.,2 Department of Genetics, University of Cambridge , Downing Street, Cambridge CB2 3EH , UK
| |
Collapse
|
21
|
Wagner JT, Howe DK, Estes S, Denver DR. Mitochondrial DNA Variation and Selfish Propagation Following Experimental Bottlenecking in Two Distantly Related Caenorhabditis briggsae Isolates. Genes (Basel) 2020; 11:genes11010077. [PMID: 31936803 PMCID: PMC7016712 DOI: 10.3390/genes11010077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
Understanding mitochondrial DNA (mtDNA) evolution and inheritance has broad implications for animal speciation and human disease models. However, few natural models exist that can simultaneously represent mtDNA transmission bias, mutation, and copy number variation. Certain isolates of the nematode Caenorhabditis briggsae harbor large, naturally-occurring mtDNA deletions of several hundred basepairs affecting the NADH dehydrogenase subunit 5 (nduo-5) gene that can be functionally detrimental. These deletion variants can behave as selfish DNA elements under genetic drift conditions, but whether all of these large deletion variants are transmitted in the same preferential manner remains unclear. In addition, the degree to which transgenerational mtDNA evolution profiles are shared between isolates that differ in their propensity to accumulate the nduo-5 deletion is also unclear. We address these knowledge gaps by experimentally bottlenecking two isolates of C. briggsae with different nduo-5 deletion frequencies for up to 50 generations and performing total DNA sequencing to identify mtDNA variation. We observed multiple mutation profile differences and similarities between C. briggsae isolates, a potentially species-specific pattern of copy number dysregulation, and some evidence for genetic hitchhiking in the deletion-bearing isolate. Our results further support C. briggsae as a practical model for characterizing naturally-occurring mtgenome variation and contribute to the understanding of how mtgenome variation persists in animal populations and how it presents in mitochondrial disease states.
Collapse
Affiliation(s)
- Josiah T. Wagner
- Cancer Early Detection Advanced Research (CEDAR) Center, Knight Cancer Institute, Oregon Health & Science University, Portland, OR 97201, USA
- Correspondence:
| | - Dana K. Howe
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA; (D.K.H.); (D.R.D.)
| | - Suzanne Estes
- Department of Biology, Portland State University, Portland, OR 97201, USA;
| | - Dee R. Denver
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA; (D.K.H.); (D.R.D.)
| |
Collapse
|
22
|
Knorre DA. Intracellular quality control of mitochondrial DNA: evidence and limitations. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190176. [PMID: 31787047 DOI: 10.1098/rstb.2019.0176] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic cells can harbour mitochondria with markedly different transmembrane potentials. Intracellular mitochondrial quality-control mechanisms (e.g. mitophagy) rely on this intracellular variation to distinguish functional and damaged (depolarized) mitochondria. Given that intracellular mitochondrial DNA (mtDNA) genetic variation can induce mitochondrial heterogeneity, mitophagy could remove deleterious mtDNA variants in cells. However, the reliance of mitophagy on the mitochondrial transmembrane potential suggests that mtDNAs with deleterious mutations in ATP synthase can evade the control. This evasion is possible because inhibition of ATP synthase can increase the mitochondrial transmembrane potential. Moreover, the linkage of the mtDNA genotype to individual mitochondrial performance is expected to be weak owing to intracellular mitochondrial intercomplementation. Nonetheless, I reason that intracellular mtDNA quality control is possible and crucial at the zygote stage of the life cycle. Indeed, species with biparental mtDNA inheritance or frequent 'leakage' of paternal mtDNA can be vulnerable to invasion of selfish mtDNAs at the stage of gamete fusion. Here, I critically review recent findings on intracellular mtDNA quality control by mitophagy and discuss other mechanisms by which the nuclear genome can affect the competition of mtDNA variants in the cell. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
Collapse
Affiliation(s)
- Dmitry A Knorre
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Leninskiye Gory 1-40, Moscow 119991, Russia.,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, Moscow 119991, Russia
| |
Collapse
|
23
|
Dubie JJ, Caraway AR, Stout MM, Katju V, Bergthorsson U. The conflict within: origin, proliferation and persistence of a spontaneously arising selfish mitochondrial genome. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190174. [PMID: 31787044 DOI: 10.1098/rstb.2019.0174] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mitochondrial genomes can sustain mutations that are simultaneously detrimental to individual fitness and yet, can proliferate within individuals owing to a replicative advantage. We analysed the fitness effects and population dynamics of a mitochondrial genome containing a novel 499 bp deletion in the cytochrome b(1) (ctb-1) gene (Δctb-1) encoding the cytochrome b of complex III in Caenorhabditis elegans. Δctb-1 reached a high heteroplasmic frequency of 96% in one experimental line during a mutation accumulation experiment and was linked to additional spontaneous mutations in nd5 and tRNA-Asn. The Δctb-1 mutant mitotype imposed a significant fitness cost including a 65% and 52% reduction in productivity and competitive fitness, respectively, relative to individuals bearing wild-type (WT) mitochondria. Deletion-bearing worms were rapidly purged within a few generations when competed against WT mitochondrial DNA (mtDNA) bearing worms in experimental populations. By contrast, the Δctb-1 mitotype was able to persist in large populations comprising heteroplasmic individuals only, although the average intracellular frequency of Δctb-1 exhibited a slow decline owing to competition among individuals bearing different frequencies of the heteroplasmy. Within experimental lines subjected to severe population bottlenecks (n = 1), the relative intracellular frequency of Δctb-1 increased, which is a hallmark of selfish drive. A positive correlation between Δctb-1 and WT mtDNA copy-number suggests a mechanism that increases total mtDNA per se, and does not discern the Δctb-1 mitotype from the WT mtDNA. This study demonstrates the selfish nature of the Δctb-1 mitotype, given its transmission advantage and substantial fitness load for the host, and highlights the importance of population size for the population dynamics of selfish mtDNA. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
Collapse
Affiliation(s)
- Joseph James Dubie
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
| | - Avery Robert Caraway
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
| | - McKenna Margaret Stout
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
| | - Vaishali Katju
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
| | - Ulfar Bergthorsson
- Department of Veterinary Integrative Biosciences, Texas A&M University, 402 Raymond Stotzer Parkway, College Station, TX 77845, USA
| |
Collapse
|
24
|
Sullins JA, Coleman-Hulbert AL, Gallegos A, Howe DK, Denver DR, Estes S. Complex Transmission Patterns and Age-Related Dynamics of a Selfish mtDNA Deletion. Integr Comp Biol 2019; 59:983-993. [PMID: 31318034 PMCID: PMC6797909 DOI: 10.1093/icb/icz128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Despite wide-ranging implications of selfish mitochondrial DNA (mtDNA) elements for human disease and topics in evolutionary biology (e.g., speciation), the forces controlling their formation, age-related accumulation, and offspring transmission remain largely unknown. Selfish mtDNA poses a significant challenge to genome integrity, mitochondrial function, and organismal fitness. For instance, numerous human diseases are associated with mtDNA mutations; however, few genetic systems can simultaneously represent pathogenic mitochondrial genome evolution and inheritance. The nematode Caenorhabditis briggsae is one such system. Natural C. briggsae isolates harbor varying levels of a large-scale deletion affecting the mitochondrial nduo-5 gene, termed nad5Δ. A subset of these isolates contains putative compensatory mutations that may reduce the risk of deletion formation. We studied the dynamics of nad5Δ heteroplasmy levels during animal development and transmission from mothers to offspring in genetically diverse C. briggsae natural isolates. Results support previous work demonstrating that nad5Δ is a selfish element and that heteroplasmy levels of this deletion can be quite plastic, exhibiting high degrees of inter-family variability and divergence between generations. The latter is consistent with a mitochondrial bottleneck effect, and contrasts with previous findings from a laboratory-derived model uaDf5 mtDNA deletion in C. elegans. However, we also found evidence for among-isolate differences in the ability to limit nad5Δ accumulation, the pattern of which suggested that forces other than the compensatory mutations are important in protecting individuals and populations from rampant mtDNA deletion expansion over short time scales.
Collapse
Affiliation(s)
- Jennifer A Sullins
- Department of Biology, Portland State University, Portland, OR 97201, USA
| | | | - Alexandra Gallegos
- Department of Biology, Portland State University, Portland, OR 97201, USA
| | - Dana K Howe
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA
| | - Dee R Denver
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA
| | - Suzanne Estes
- Department of Biology, Portland State University, Portland, OR 97201, USA
| |
Collapse
|
25
|
Stegeman GW, Baird SE, Ryu WS, Cutter AD. Genetically Distinct Behavioral Modules Underlie Natural Variation in Thermal Performance Curves. G3 (BETHESDA, MD.) 2019; 9:2135-2151. [PMID: 31048400 PMCID: PMC6643873 DOI: 10.1534/g3.119.400043] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/30/2019] [Indexed: 01/01/2023]
Abstract
Thermal reaction norms pervade organismal traits as stereotyped responses to temperature, a fundamental environmental input into sensory and physiological systems. Locomotory behavior represents an especially plastic read-out of animal response, with its dynamic dependence on environmental stimuli presenting a challenge for analysis and for understanding the genomic architecture of heritable variation. Here we characterize behavioral reaction norms as thermal performance curves for the nematode Caenorhabditis briggsae, using a collection of 23 wild isolate genotypes and 153 recombinant inbred lines to quantify the extent of genetic and plastic variation in locomotory behavior to temperature changes. By reducing the dimensionality of the multivariate phenotypic response with a function-valued trait framework, we identified genetically distinct behavioral modules that contribute to the heritable variation in the emergent overall behavioral thermal performance curve. Quantitative trait locus mapping isolated regions on Chromosome II associated with locomotory activity at benign temperatures and Chromosome V loci related to distinct aspects of sensitivity to high temperatures, with each quantitative trait locus explaining up to 28% of trait variation. These findings highlight how behavioral responses to environmental inputs as thermal reaction norms can evolve through independent changes to genetically distinct modular components of such complex phenotypes.
Collapse
Affiliation(s)
| | - Scott E Baird
- Department of Biology, Wright State University, Dayton, Ohio, 45435
| | - William S Ryu
- Department of Physics, University of Toronto
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S3B2, Canada
| | - Asher D Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto
| |
Collapse
|
26
|
Li R, Ren X, Bi Y, Ding Q, Ho VWS, Zhao Z. Comparative mitochondrial genomics reveals a possible role of a recent duplication of NADH dehydrogenase subunit 5 in gene regulation. DNA Res 2018; 25:577-586. [PMID: 30085012 PMCID: PMC6289777 DOI: 10.1093/dnares/dsy026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 07/22/2018] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial genome (mtDNA) carries not only well-conserved protein coding, tRNA and rRNA genes, but also highly variable non-coding regions (NCRs). However, the NCRs show poor conservation across species, making their function and evolution elusive. Identification and functional characterization of NCRs across species would be critical for addressing these questions. To this end, we devised a computational pipeline and performed de novo assembly and annotation of mtDNA from 19 Caenorhabditis species using next-generation sequencing (NGS) data. The mtDNAs for 14 out of the 19 species are reported for the first time. Comparison of the 19 genomes reveals species-specific sampling of partial displacement-loop (D-loop) sequence as a novel NCR inserted into a unique tRNA cluster, suggesting an important role of the D-loop and the tRNA cluster in shaping NCR evolution. Intriguingly, RNA-Seq analysis suggests that a novel NCR resulting from a recent duplication of NADH dehydrogenase subunit 5 (ND5) could be utilized as a 3' UTR for up-regulation of its upstream gene. The expression analysis shows a species- and sex-specific expression of mitochondrial genes encoded by mtDNA and nucleus, respectively. Our analyses provide important insights into the function and evolution of mitochondrial NCRs and pave the way for further studying the function and evolution of mitochondrial genome.
Collapse
Affiliation(s)
- Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yu Bi
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Qiutao Ding
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
- State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China
| |
Collapse
|
27
|
Ha AD, Denver DR. Comparative Genomic Analysis of 130 Bacteriophages Infecting Bacteria in the Genus Pseudomonas. Front Microbiol 2018; 9:1456. [PMID: 30022972 PMCID: PMC6039544 DOI: 10.3389/fmicb.2018.01456] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 06/12/2018] [Indexed: 11/16/2022] Open
Abstract
Bacteria of the genus Pseudomonas are genetically diverse and ubiquitous in the environment. Like other bacteria, those of the genus Pseudomonas are susceptible to bacteriophages which can significantly affect their host in many ways, ranging from cell lysis to major changes in morphology and virulence. Insights into phage genomes, evolution, and functional relationships with their hosts have the potential to contribute to a broader understanding of Pseudomonas biology, and the development of novel phage therapy strategies. Here we provide a broad-based comparative and evolutionary analysis of 130 complete Pseudomonas phage genome sequences available in online databases. We discovered extensive variation in genome size (ranging from 3 to 316 kb), G + C percentage (ranging from 37 to 66%), and overall gene content (ranging from 81–96% of genome space). Based on overall nucleotide similarity and the numbers of shared gene products, 100 out of 130 genome sequences were grouped into 12 different clusters; 30 were characterized as singletons, which do not have close relationships with other phage genomes. For 5/12 clusters, constituent phage members originated from two or more different Pseudomonas host species, suggesting that phage in these clusters can traverse bacterial species boundaries. An analysis of CRISPR spacers in Pseudomonas bacterial genome sequences supported this finding. Substantial diversity was revealed in analyses of phage gene families; out of 4,462 total families, the largest had only 39 members and there were 2,992 families with only one member. An evolutionary analysis of 72 phage gene families, based on patterns of nucleotide diversity at non-synonymous and synonymous sites, revealed strong and consistent signals for purifying selection. Our study revealed highly diverse and dynamic Pseudomonas phage genomes, and evidence for a dominant role of purifying selection in shaping the evolution of genes encoded in them.
Collapse
Affiliation(s)
- Anh D Ha
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States
| | - Dee R Denver
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States
| |
Collapse
|
28
|
Christie JR, Beekman M. Uniparental Inheritance Promotes Adaptive Evolution in Cytoplasmic Genomes. Mol Biol Evol 2017; 34:677-691. [PMID: 28025277 PMCID: PMC5896580 DOI: 10.1093/molbev/msw266] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Eukaryotes carry numerous asexual cytoplasmic genomes (mitochondria and plastids). Lacking recombination, asexual genomes should theoretically suffer from impaired adaptive evolution. Yet, empirical evidence indicates that cytoplasmic genomes experience higher levels of adaptive evolution than predicted by theory. In this study, we use a computational model to show that the unique biology of cytoplasmic genomes-specifically their organization into host cells and their uniparental (maternal) inheritance-enable them to undergo effective adaptive evolution. Uniparental inheritance of cytoplasmic genomes decreases competition between different beneficial substitutions (clonal interference), promoting the accumulation of beneficial substitutions. Uniparental inheritance also facilitates selection against deleterious cytoplasmic substitutions, slowing Muller's ratchet. In addition, uniparental inheritance generally reduces genetic hitchhiking of deleterious substitutions during selective sweeps. Overall, uniparental inheritance promotes adaptive evolution by increasing the level of beneficial substitutions relative to deleterious substitutions. When we assume that cytoplasmic genome inheritance is biparental, decreasing the number of genomes transmitted during gametogenesis (bottleneck) aids adaptive evolution. Nevertheless, adaptive evolution is always more efficient when inheritance is uniparental. Our findings explain empirical observations that cytoplasmic genomes-despite their asexual mode of reproduction-can readily undergo adaptive evolution.
Collapse
Affiliation(s)
- Joshua R Christie
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Madeleine Beekman
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| |
Collapse
|
29
|
Ross JA, Howe DK, Coleman-Hulbert A, Denver DR, Estes S. Paternal Mitochondrial Transmission in Intra-Species Caenorhabditis briggsae Hybrids. Mol Biol Evol 2016; 33:3158-3160. [PMID: 27613821 PMCID: PMC5100050 DOI: 10.1093/molbev/msw192] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
To study mitochondrial–nuclear genetic interactions in the nematode Caenorhabditis briggsae, our three laboratories independently created 38 intra-species cytoplasmic–nuclear hybrid (cybrid) lines. Although the cross design combines maternal mitotypes with paternal nuclear genotypes, eight lines (21%) unexpectedly contained paternal mitotypes. All eight share in common ancestry of one of two genetically related strains. This unexpected parallel observation of paternal mitochondrial transmission, undesirable given our intent of creating cybrids, provides a serendipitous experimental model and framework to study the molecular and evolutionary basis of uniparental mitochondrial inheritance.
Collapse
Affiliation(s)
- Joseph A Ross
- Department of Biology, California State University, Fresno, CA
| | - Dana K Howe
- Department of Integrative Biology, Oregon State University, Corvallis, OR
| | - Anna Coleman-Hulbert
- Department of Biology, Portland State University, Portland, OR.,Institute of Ecology and Evolution, University of Oregon, Eugene, OR
| | - Dee R Denver
- Department of Integrative Biology, Oregon State University, Corvallis, OR
| | - Suzanne Estes
- Department of Biology, Portland State University, Portland, OR
| |
Collapse
|
30
|
Gitschlag BL, Kirby CS, Samuels DC, Gangula RD, Mallal SA, Patel MR. Homeostatic Responses Regulate Selfish Mitochondrial Genome Dynamics in C. elegans. Cell Metab 2016; 24:91-103. [PMID: 27411011 PMCID: PMC5287496 DOI: 10.1016/j.cmet.2016.06.008] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 05/27/2016] [Accepted: 06/13/2016] [Indexed: 02/08/2023]
Abstract
Mutant mitochondrial genomes (mtDNA) can be viewed as selfish genetic elements that persist in a state of heteroplasmy despite having potentially deleterious metabolic consequences. We sought to study regulation of selfish mtDNA dynamics. We establish that the large 3.1-kb deletion-bearing mtDNA variant uaDf5 is a selfish genome in Caenorhabditis elegans. Next, we show that uaDf5 mutant mtDNA replicates in addition to, not at the expense of, wild-type mtDNA. These data suggest the existence of a homeostatic copy-number control that is exploited by uaDf5 to "hitchhike" to high frequency. We also observe activation of the mitochondrial unfolded protein response (UPR(mt)) in uaDf5 animals. Loss of UPR(mt) causes a decrease in uaDf5 frequency, whereas its constitutive activation increases uaDf5 levels. UPR(mt) activation protects uaDf5 from mitophagy. Taken together, we propose that mtDNA copy-number control and UPR(mt) represent two homeostatic response mechanisms that play important roles in regulating selfish mitochondrial genome dynamics.
Collapse
Affiliation(s)
- Bryan L Gitschlag
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Interdisciplinary Graduate Program, Vanderbilt University, Nashville, TN 37232, USA
| | - Cait S Kirby
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Biological Sciences Graduate Program, Vanderbilt University, Nashville, TN 37232, USA
| | - David C Samuels
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Rama D Gangula
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Simon A Mallal
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Institute for Immunology and Infectious Diseases, Murdoch University, Murdoch, WA 6150, Australia
| | - Maulik R Patel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.
| |
Collapse
|
31
|
Grosemans T, Morris K, Thomas WK, Rigaux A, Moens T, Derycke S. Mitogenomics reveals high synteny and long evolutionary histories of sympatric cryptic nematode species. Ecol Evol 2016; 6:1854-70. [PMID: 26933490 PMCID: PMC4760989 DOI: 10.1002/ece3.1975] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/18/2015] [Accepted: 01/03/2016] [Indexed: 11/09/2022] Open
Abstract
Species with seemingly identical morphology but with distinct genetic differences are abundant in the marine environment and frequently co-occur in the same habitat. Such cryptic species are typically delineated using a limited number of mitochondrial and/or nuclear marker genes, which do not yield information on gene order and gene content of the genomes under consideration. We used next-generation sequencing to study the composition of the mitochondrial genomes of four sympatrically distributed cryptic species of the Litoditis marina species complex (PmI, PmII, PmIII, and PmIV). The ecology, biology, and natural occurrence of these four species are well known, but the evolutionary processes behind this cryptic speciation remain largely unknown. The gene order of the mitochondrial genomes of the four species was conserved, but differences in genome length, gene length, and codon usage were observed. The atp8 gene was lacking in all four species. Phylogenetic analyses confirm that PmI and PmIV are sister species and that PmIII diverged earliest. The most recent common ancestor of the four cryptic species was estimated to have diverged 16 MYA. Synonymous mutations outnumbered nonsynonymous changes in all protein-encoding genes, with the Complex IV genes (coxI-III) experiencing the strongest purifying selection. Our mitogenomic results show that morphologically similar species can have long evolutionary histories and that PmIII has several differences in genetic makeup compared to the three other species, which may explain why it is better adapted to higher temperatures than the other species.
Collapse
Affiliation(s)
- Tara Grosemans
- Marine Biology Section Biology Department Faculty of Science University of Ghent Krijgslaan 281 (S8) 9000 Gent Belgium
| | - Krystalynne Morris
- Department of Biochemistry and Molecular Biology Hubbard Center for Genome Studies University of New Hampshire 35 Colovos Road Durham New Hampshire 03824
| | - William Kelley Thomas
- Department of Biochemistry and Molecular Biology Hubbard Center for Genome Studies University of New Hampshire 35 Colovos Road Durham New Hampshire 03824
| | - Annelien Rigaux
- Marine Biology Section Biology Department Faculty of Science University of Ghent Krijgslaan 281 (S8) 9000 Gent Belgium; CeMoFe University of Ghent Karel Lodewijk Ledeganckstraat 359000 Gent Belgium
| | - Tom Moens
- Marine Biology Section Biology Department Faculty of Science University of Ghent Krijgslaan 281 (S8) 9000 Gent Belgium
| | - Sofie Derycke
- Marine Biology Section Biology Department Faculty of Science University of Ghent Krijgslaan 281 (S8) 9000 Gent Belgium; Royal Belgian Institute of Natural Sciences (RBINS) OD Taxonomy and Phylogeny Vautierstraat 291000 Brussels Belgium
| |
Collapse
|
32
|
Rollins LA, Woolnough AP, Fanson BG, Cummins ML, Crowley TM, Wilton AN, Sinclair R, Butler A, Sherwin WB. Selection on Mitochondrial Variants Occurs between and within Individuals in an Expanding Invasion. Mol Biol Evol 2016; 33:995-1007. [DOI: 10.1093/molbev/msv343] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
|
33
|
Chang CC, Rodriguez J, Ross J. Mitochondrial-Nuclear Epistasis Impacts Fitness and Mitochondrial Physiology of Interpopulation Caenorhabditis briggsae Hybrids. G3 (BETHESDA, MD.) 2015; 6:209-19. [PMID: 26585825 PMCID: PMC4704720 DOI: 10.1534/g3.115.022970] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/16/2015] [Indexed: 12/18/2022]
Abstract
In order to identify the earliest genetic changes that precipitate species formation, it is useful to study genetic incompatibilities that cause only mild dysfunction when incompatible alleles are combined in an interpopulation hybrid. Such hybridization within the nematode species Caenorhabditis briggsae has been suggested to result in selection against certain combinations of nuclear and mitochondrial alleles, raising the possibility that mitochondrial-nuclear (mitonuclear) epistasis reduces hybrid fitness. To test this hypothesis, cytoplasmic-nuclear hybrids (cybrids) were created to purposefully disrupt any epistatic interactions. Experimental analysis of the cybrids suggests that mitonuclear discord can result in decreased fecundity, increased lipid content, and increased mitochondrial reactive oxygen species levels. Many of these effects were asymmetric with respect to cross direction, as expected if cytoplasmic-nuclear Dobzhansky-Muller incompatibilities exist. One such effect is consistent with the interpretation that disrupting coevolved mitochondrial and nuclear loci impacts mitochondrial function and organismal fitness. These findings enhance efforts to study the genesis, identity, and maintenance of genetic incompatibilities that precipitate the speciation process.
Collapse
Affiliation(s)
- Chih-Chiun Chang
- Department of Biology, California State University, Fresno, California, 93740
| | - Joel Rodriguez
- Department of Biology, California State University, Fresno, California, 93740
| | - Joseph Ross
- Department of Biology, California State University, Fresno, California, 93740
| |
Collapse
|
34
|
Bundus JD, Alaei R, Cutter AD. Gametic selection, developmental trajectories, and extrinsic heterogeneity in Haldane's rule. Evolution 2015; 69:2005-17. [PMID: 26102479 DOI: 10.1111/evo.12708] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/01/2015] [Indexed: 12/31/2022]
Abstract
Deciphering the genetic and developmental causes of the disproportionate rarity, inviability, and sterility of hybrid males, Haldane's rule, is important for understanding the evolution of reproductive isolation between species. Moreover, extrinsic and prezygotic factors can contribute to the magnitude of intrinsic isolation experienced between species with partial reproductive compatibility. Here, we use the nematodes Caenorhabditis briggsae and C. nigoni to quantify the sensitivity of hybrid male viability to extrinsic temperature and developmental timing, and test for a role of mito-nuclear incompatibility as a genetic cause. We demonstrate that hybrid male inviability manifests almost entirely as embryonic, not larval, arrest and is maximal at the lowest rearing temperatures, indicating an intrinsic-by-extrinsic interaction to hybrid inviability. Crosses using mitochondrial substitution strains that have reciprocally introgressed mitochondrial and nuclear genomes show that mito-nuclear incompatibility is not a dominant contributor to postzygotic isolation and does not drive Haldane's rule in this system. Crosses also reveal that competitive superiority of X-bearing sperm provides a novel means by which postmating prezygotic factors exacerbate the rarity of hybrid males. These findings highlight the important roles of gametic, developmental, and extrinsic factors in modulating the manifestation of Haldane's rule.
Collapse
Affiliation(s)
- Joanna D Bundus
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Ravin Alaei
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2.
| |
Collapse
|
35
|
Phillips WS, Coleman-Hulbert AL, Weiss ES, Howe DK, Ping S, Wernick RI, Estes S, Denver DR. Selfish Mitochondrial DNA Proliferates and Diversifies in Small, but not Large, Experimental Populations of Caenorhabditis briggsae. Genome Biol Evol 2015; 7:2023-37. [PMID: 26108490 PMCID: PMC4524483 DOI: 10.1093/gbe/evv116] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Evolutionary interactions across levels of biological organization contribute to a variety of fundamental processes including genome evolution, reproductive mode transitions, species diversification, and extinction. Evolutionary theory predicts that so-called “selfish” genetic elements will proliferate when the host effective population size (Ne) is small, but direct tests of this prediction remain few. We analyzed the evolutionary dynamics of deletion-containing mitochondrial DNA (ΔmtDNA) molecules, previously characterized as selfish elements, in six different natural strains of the nematode Caenorhabditis briggsae allowed to undergo experimental evolution in a range of population sizes (N = 1, 10, 100, and 1,000) for a maximum of 50 generations. Mitochondrial DNA (mtDNA) was analyzed for replicate lineages at each five-generation time point. Ten different ΔmtDNA molecule types were observed and characterized across generations in the experimental populations. Consistent with predictions from evolutionary theory, lab lines evolved in small-population sizes (e.g., nematode N = 1) were more susceptible to accumulation of high levels of preexisting ΔmtDNA compared with those evolved in larger populations. New ΔmtDNA elements were observed to increase in frequency and persist across time points, but almost exclusively at small population sizes. In some cases, ΔmtDNA levels decreased across generations when population size was large (nematode N = 1,000). Different natural strains of C. briggsae varied in their susceptibilities to ΔmtDNA accumulation, owing in part to preexisting compensatory mtDNA alleles in some strains that prevent deletion formation. This analysis directly demonstrates that the evolutionary trajectories of ΔmtDNA elements depend upon the population-genetic environments and molecular-genetic features of their hosts.
Collapse
Affiliation(s)
| | | | - Emily S Weiss
- Department of Integrative Biology, Oregon State University
| | - Dana K Howe
- Department of Integrative Biology, Oregon State University
| | - Sita Ping
- Department of Integrative Biology, Oregon State University
| | | | | | - Dee R Denver
- Department of Integrative Biology, Oregon State University
| |
Collapse
|
36
|
Otten ABC, Smeets HJM. Evolutionary defined role of the mitochondrial DNA in fertility, disease and ageing. Hum Reprod Update 2015; 21:671-89. [PMID: 25976758 DOI: 10.1093/humupd/dmv024] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 04/22/2015] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The endosymbiosis of an alpha-proteobacterium and a eubacterium a billion years ago paved the way for multicellularity and enabled eukaryotes to flourish. The selective advantage for the host was the acquired ability to generate large amounts of intracellular hydrogen-dependent adenosine triphosphate. The price was increased reactive oxygen species (ROS) inside the eukaryotic cell, causing high mutation rates of the mitochondrial DNA (mtDNA). According to the Muller's ratchet theory, this accumulation of mutations in asexually transmitted mtDNA would ultimately lead to reduced reproductive fitness and eventually extinction. However, mitochondria have persisted over the course of evolution, initially due to a rapid, extreme evolutionary reduction of the mtDNA content. After the phylogenetic divergence of eukaryotes into animals, fungi and plants, differences in evolution of the mtDNA occurred with different adaptations for coping with the mutation burden within these clades. As a result, mitochondrial evolutionary mechanisms have had a profound effect on human adaptation, fertility, healthy reproduction, mtDNA disease manifestation and transmission and ageing. An understanding of these mechanisms might elucidate novel approaches for treatment and prevention of mtDNA disease. METHODS The scientific literature was investigated to determine how mtDNA evolved in animals, plants and fungi. Furthermore, the different mechanisms of mtDNA inheritance and of balancing Muller's ratchet in these species were summarized together with the consequences of these mechanisms for human health and reproduction. RESULTS Animal, plant and fungal mtDNA have evolved differently. Animals have compact genomes, little recombination, a stable number of genes and a high mtDNA copy number, whereas plants have larger genomes with variable gene counts, a low mtDNA copy number and many recombination events. Fungal mtDNA is somewhere in between. In plants, the mtDNA mutation rate is kept low by effective ROS defence and efficient recombination-mediated mtDNA repair. In animal mtDNA, these mechanisms are not or less well-developed and the detrimental mutagenesis events are controlled by a high mtDNA copy number in combination with a genetic bottleneck and purifying selection during transmission. The mtDNA mutation rates in animals are higher than in plants, which allow mobile animals to adapt more rapidly to various environmental conditions in terms of energy production, whereas static plants do not have this need. Although at the level of the species, these mechanisms have been extremely successful, they can have adverse effects for the individual, resulting, in humans, in severe or unpredictably segregating mtDNA diseases, as well as fertility problems and unhealthy ageing. CONCLUSIONS Understanding the forces and processes that underlie mtDNA evolution among different species increases our knowledge on the detrimental consequences that individuals can have from these evolutionary end-points. Alternative outcomes in animals, fungi and plants will lead to a better understanding of the inheritance of mtDNA disorders and mtDNA-related fertility problems. These will allow the development of options to ameliorate, cure and/or prevent mtDNA diseases and mtDNA-related fertility problems.
Collapse
Affiliation(s)
- Auke B C Otten
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, PO box 616 (box 16), 6200 MD Maastricht, The Netherlands School for Oncology and Developmental Biology (GROW), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Hubert J M Smeets
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, PO box 616 (box 16), 6200 MD Maastricht, The Netherlands School for Oncology and Developmental Biology (GROW), Maastricht University Medical Centre, Maastricht, The Netherlands
| |
Collapse
|
37
|
Li R, Ren X, Bi Y, Zhao Z. Mitochondrial genome of Caenorhabditis nigoni (Rhabditida: Rhabditidae). Mitochondrial DNA A DNA Mapp Seq Anal 2015; 27:3107-8. [PMID: 25740213 DOI: 10.3109/19401736.2015.1007287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To facilitate comparative genomic study in the Caenorhabditis species, the mitochondrial genome (mitogenome) of a nematode species Caenorhabditis nigoni (previous name: Caenorhabditis sp. 9) was generated using next-generation sequencing. The mitogenome length is 13,413 bp, containing 12 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs) and 2 non-coding regions (NCR). The genome organization and nucleotide composition is very similar to that of the mitogenome of C. elegans and C. briggsae. Mitogenome of C. nigoni shows higher sequence similarity to C. briggsae than to C. elegans, which is consistent with the fact that C. nigoni is a sister species of C. briggsae. However, as in C. elegans, two NCRs present in the mitogenome of C. briggsae are missing in C. nigoni. The mitogenome sequence of C. nigoni plays an important role in further studies of phylogenetics, population genetics and evolutionary genetics in nematode species.
Collapse
Affiliation(s)
- Runsheng Li
- a Department of Biology , Hong Kong Baptist University , Hong Kong , China and
| | - Xiaoliang Ren
- a Department of Biology , Hong Kong Baptist University , Hong Kong , China and
| | - Yu Bi
- a Department of Biology , Hong Kong Baptist University , Hong Kong , China and
| | - Zhongying Zhao
- a Department of Biology , Hong Kong Baptist University , Hong Kong , China and.,b State Key Laboratory of Environmental and Biological Analysis , Hong Kong Baptist University , Hong Kong , China
| |
Collapse
|
38
|
Effect of drift, selection and recombination on the equilibrium frequency of deleterious mutations. J Theor Biol 2015; 365:238-46. [PMID: 25451760 DOI: 10.1016/j.jtbi.2014.10.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 08/30/2014] [Accepted: 10/22/2014] [Indexed: 11/22/2022]
Abstract
We study the stationary state of a population evolving under the action of random genetic drift, selection and recombination in which both deleterious and reverse beneficial mutations can occur. We find that the equilibrium fraction of deleterious mutations decreases as the population size is increased. We calculate exactly the steady state frequency in a nonrecombining population when population size is infinite and for a neutral finite population, and obtain bounds on the fraction of deleterious mutations. We also find that for small and very large populations, the number of deleterious mutations depends weakly on recombination, but for moderately large populations, recombination alleviates the effect of deleterious mutations. An analytical argument shows that recombination decreases disadvantageous mutations appreciably when beneficial mutations are rare as is the case in adapting microbial populations, whereas it has a moderate effect on codon bias where the mutation rates between the preferred and unpreferred codons are comparable.
Collapse
|
39
|
Chen SC, Wei DD, Shao R, Shi JX, Dou W, Wang JJ. Evolution of multipartite mitochondrial genomes in the booklice of the genus Liposcelis (Psocoptera). BMC Genomics 2014; 15:861. [PMID: 25282613 PMCID: PMC4197233 DOI: 10.1186/1471-2164-15-861] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 09/29/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The genus Liposcelis (Psocoptera: Troctomorpha) has more than 120 species with a worldwide distribution and they pose a risk for global food security. The organization of mitochondrial (mt) genomes varies between the two species of booklice investigated in the genus Liposcelis. Liposcelis decolor has its mt genes on a single chromosome, like most other insects; L. bostrychophila, however, has a multipartite mt genome with genes on two chromosomes. RESULTS To understand how multipartite mt genome organization evolved in the genus Liposcelis, we sequenced the mt genomes of L. entomophila and L. paeta in this study. We found that these two species of booklice also have multipartite mt genomes, like L. bostrychophila, with the mt genes we identified on two chromosomes. Numerous pseudo mt genes and non-coding regions were found in the mt genomes of these two booklice, and account for 30% and 10% respectively of the entire length we sequenced. In L. bostrychophila, the mt genes are distributed approximately equally between the two chromosomes. In L. entomophila and L. paeta, however, one mt chromosome has most of the genes we identified whereas the other chromosome has largely pseudogenes and non-coding regions. L. entomophila and L. paeta differ substantially from each other and from L. bostrychophila in gene content and gene arrangement in their mt chromosomes. CONCLUSIONS Our results indicate unusually fast evolution in mt genome organization in the booklice of the genus Liposcelis, and reveal different patterns of mt genome fragmentation among L. bostrychophila, L. entomophila and L. paeta.
Collapse
Affiliation(s)
| | | | | | | | | | - Jin-Jun Wang
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, P, R, China.
| |
Collapse
|
40
|
Using mitogenomic and nuclear ribosomal sequence data to investigate the phylogeny of the Xiphinema americanum species complex. PLoS One 2014; 9:e90035. [PMID: 24587203 PMCID: PMC3937401 DOI: 10.1371/journal.pone.0090035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 01/28/2014] [Indexed: 01/14/2023] Open
Abstract
Nematodes within the Xiphinema americanum species complex are economically important because they vector nepoviruses which cause considerable damage to a variety of agricultural crops. The taxonomy of X. americanum species complex is controversial, with the number of putative species being the subject of debate. Accurate phylogenetic knowledge of this group is highly desirable as it may ultimately reveal genetic differences between species. For this study, nematodes belonging to the X. americanum species complex, including potentially mixed species populations, were collected from 12 geographically disparate locations across the U.S. from different crops and in varying association with nepoviruses. At least four individuals from each population were analyzed. A portion of the 18S nuclear ribosomal DNA (rDNA) gene was sequenced for all individuals while the internal transcribed spacer region 1 (ITS1) of rDNA was cloned and 2 to 6 clones per individual were sequenced. Mitochondrial genomes for numerous individuals were sequenced in parallel using high-throughput DNA sequencing (HTS) technology. Phylogenetic analysis of the 18S rDNA revealed virtually identical sequences across all populations. Analysis of ITS1 rDNA sequences revealed several well-supported clades, with some degree of congruence with geographic location and viral transmission, but also numerous presumably paralogous sequences that failed to form clades with other sequences from the same population. Analysis of mitochondrial DNA (mtDNA) indicated the presence of three distinct monophyletic clades of X. americanum species complex nematodes. Two clades contained nematodes found in association with nepovirus and the third contained divergent mtDNA sequences from three nematode populations from the western U.S. where nepovirus was absent. The inherent heterogeneity in ITS1 rDNA sequence data and lack of informative sites in 18S rDNA analysis suggests that mtDNA may be more useful in sorting out the taxonomic confusion of the X. americanum species complex.
Collapse
|
41
|
Metzger JJ, Eule S. Distribution of the fittest individuals and the rate of Muller's ratchet in a model with overlapping generations. PLoS Comput Biol 2013; 9:e1003303. [PMID: 24244123 PMCID: PMC3820511 DOI: 10.1371/journal.pcbi.1003303] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 09/10/2013] [Indexed: 11/17/2022] Open
Abstract
Muller's ratchet is a paradigmatic model for the accumulation of deleterious mutations in a population of finite size. A click of the ratchet occurs when all individuals with the least number of deleterious mutations are lost irreversibly due to a stochastic fluctuation. In spite of the simplicity of the model, a quantitative understanding of the process remains an open challenge. In contrast to previous works, we here study a Moran model of the ratchet with overlapping generations. Employing an approximation which describes the fittest individuals as one class and the rest as a second class, we obtain closed analytical expressions of the ratchet rate in the rare clicking regime. As a click in this regime is caused by a rare, large fluctuation from a metastable state, we do not resort to a diffusion approximation but apply an approximation scheme which is especially well suited to describe extinction events from metastable states. This method also allows for a derivation of expressions for the quasi-stationary distribution of the fittest class. Additionally, we confirm numerically that the formulation with overlapping generations leads to the same results as the diffusion approximation and the corresponding Wright-Fisher model with non-overlapping generations. Muller's ratchet is a paradigmatic model in population genetics which describes the fixation of a deleterious mutation in a population of finite size due to an unfortunate stochastic fluctuation. Obtaining quantitative predictions of the ratchet rate, i.e. the frequency with which such a mutation fixes, is believed to be important for understanding a broad range of effects ranging from the degeneration of the Y-chromosome to the evolution of sex as a means of avoiding the fixation of deleterious mutations. To obtain a better understanding of how Muller's ratchet operates, we have considered a model with overlapping generations, which allows for the application of methods specifically tailored for the analysis of rare stochastic fluctuations which drive the ratchet. We obtain concise and accurate results for the rate of Muller's ratchet. Additionally, we are able to predict the full distribution of the frequency of the fittest individuals, a quantity of central interest in understanding the ratchet rate and possibly experimentally much more accessible than the rate, in particular when the ratchet rate is very large.
Collapse
Affiliation(s)
- Jakob J Metzger
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), Göttingen, Germany ; Institute for Nonlinear Dynamics, Department of Physics, University of Göttingen, Göttingen, Germany
| | | |
Collapse
|
42
|
van der Nest MA, Steenkamp ET, Wilken MP, Stenlid J, Wingfield MJ, Wingfield BD, Slippers B. Mutualism and asexual reproduction influence recognition genes in a fungal symbiont. Fungal Biol 2013; 117:439-50. [PMID: 23809654 DOI: 10.1016/j.funbio.2013.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 04/23/2013] [Accepted: 05/01/2013] [Indexed: 11/20/2022]
Abstract
Mutualism between microbes and insects is common and alignment of the reproductive interests of microbial symbionts with this lifestyle typically involves clonal reproduction and vertical transmission by insect partners. Here the Amylostereum fungus-Sirex woodwasp mutualism was used to consider whether their prolonged association and predominance of asexuality have affected the mating system of the fungal partner. Nucleotide information for the pheromone receptor gene rab1, as well as the translation elongation factor 1α gene and ribosomal RNA internal transcribed spacer region were utilized. The identification of rab1 alleles in Amylostereum chailletii and Amylostereum areolatum populations revealed that this gene is more polymorphic than the other two regions, although the diversity of all three regions was lower than what has been observed in free-living Agaricomycetes. Our data suggest that suppressed recombination might be implicated in the diversification of rab1, while no evidence of balancing selection was detected. We also detected positive selection at only two codons, suggesting that purifying selection is important for the evolution of rab1. The symbiotic relationship with their insect partners has therefore influenced the diversity of this gene and influenced the manner in which selection drives and maintains this diversity in A. areolatum and A. chailletii.
Collapse
MESH Headings
- Animals
- Basidiomycota/genetics
- Basidiomycota/physiology
- Cluster Analysis
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Ribosomal Spacer/chemistry
- DNA, Ribosomal Spacer/genetics
- Genes, Mating Type, Fungal
- Hymenoptera/microbiology
- Molecular Sequence Data
- Peptide Elongation Factor 1/genetics
- Polymorphism, Genetic
- Receptors, Pheromone/genetics
- Recombination, Genetic
- Sequence Analysis, DNA
- Symbiosis
Collapse
Affiliation(s)
- Magriet A van der Nest
- Department of Genetics, Forestry and Agricultural Biotechnology Institute-FABI, University of Pretoria, Pretoria 0002, South Africa
| | | | | | | | | | | | | |
Collapse
|
43
|
Félix MA, Jovelin R, Ferrari C, Han S, Cho YR, Andersen EC, Cutter AD, Braendle C. Species richness, distribution and genetic diversity of Caenorhabditis nematodes in a remote tropical rainforest. BMC Evol Biol 2013; 13:10. [PMID: 23311925 PMCID: PMC3556333 DOI: 10.1186/1471-2148-13-10] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 01/07/2013] [Indexed: 11/30/2022] Open
Abstract
Background In stark contrast to the wealth of detail about C. elegans developmental biology and molecular genetics, biologists lack basic data for understanding the abundance and distribution of Caenorhabditis species in natural areas that are unperturbed by human influence. Methods Here we report the analysis of dense sampling from a small, remote site in the Amazonian rain forest of the Nouragues Natural Reserve in French Guiana. Results Sampling of rotting fruits and flowers revealed proliferating populations of Caenorhabditis, with up to three different species co-occurring within a single substrate sample, indicating remarkable overlap of local microhabitats. We isolated six species, representing the highest local species richness for Caenorhabditis encountered to date, including both tropically cosmopolitan and geographically restricted species not previously isolated elsewhere. We also documented the structure of within-species molecular diversity at multiple spatial scales, focusing on 57 C. briggsae isolates from French Guiana. Two distinct genetic subgroups co-occur even within a single fruit. However, the structure of C. briggsae population genetic diversity in French Guiana does not result from strong local patterning but instead presents a microcosm of global patterns of differentiation. We further integrate our observations with new data from nearly 50 additional recently collected C. briggsae isolates from both tropical and temperate regions of the world to re-evaluate local and global patterns of intraspecific diversity, providing the most comprehensive analysis to date for C. briggsae population structure across multiple spatial scales. Conclusions The abundance and species richness of Caenorhabditis nematodes is high in a Neotropical rainforest habitat that is subject to minimal human interference. Microhabitat preferences overlap for different local species, although global distributions include both cosmopolitan and geographically restricted groups. Local samples for the cosmopolitan C. briggsae mirror its pan-tropical patterns of intraspecific polymorphism. It remains an important challenge to decipher what drives Caenorhabditis distributions and diversity within and between species.
Collapse
Affiliation(s)
- Marie-Anne Félix
- Institut de Biologie Valrose, CNRS, UMR7277, Parc Valrose, Nice cedex 02, 06108, France
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Hicks KA, Denver DR, Estes S. Natural variation in Caenorhabditis briggsae mitochondrial form and function suggests a novel model of organelle dynamics. Mitochondrion 2012; 13:44-51. [PMID: 23269324 DOI: 10.1016/j.mito.2012.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/07/2012] [Accepted: 12/18/2012] [Indexed: 01/28/2023]
Abstract
Mitochondrial functioning and morphology are known to be connected through cycles of organelle fusion and fission that depend upon the mitochondrial membrane potential (ΔΨM); however, we lack an understanding of the features and dynamics of natural mitochondrial populations. Using data from our recent study of univariate mitochondrial phenotypic variation in Caenorhabditis briggsae nematodes, we analyzed patterns of phenotypic correlation for 24 mitochondrial traits. Our findings support a role for ΔΨM in shaping mitochondrial dynamics, but no role for mitochondrial ROS. Further, our study suggests a novel model of mitochondrial population dynamics dependent upon cellular environmental context and with implications for mitochondrial genome integrity.
Collapse
Affiliation(s)
- Kiley A Hicks
- Biology Department, Portland State University, 1719 SW 10th Ave., Portland, OR 97201, USA.
| | | | | |
Collapse
|
45
|
Pfaffelhuber P, Staab PR, Wakolbinger A. Muller’s ratchet with compensatory mutations. ANN APPL PROBAB 2012. [DOI: 10.1214/11-aap836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
46
|
Hicks KA, Howe DK, Leung A, Denver DR, Estes S. In vivo quantification reveals extensive natural variation in mitochondrial form and function in Caenorhabditis briggsae. PLoS One 2012; 7:e43837. [PMID: 22952781 PMCID: PMC3429487 DOI: 10.1371/journal.pone.0043837] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 07/30/2012] [Indexed: 12/18/2022] Open
Abstract
We have analyzed natural variation in mitochondrial form and function among a set of Caenorhabditis briggsae isolates known to harbor mitochondrial DNA structural variation in the form of a heteroplasmic nad5 gene deletion (nad5Δ) that correlates negatively with organismal fitness. We performed in vivo quantification of 24 mitochondrial phenotypes including reactive oxygen species level, membrane potential, and aspects of organelle morphology, and observed significant among-isolate variation in 18 traits. Although several mitochondrial phenotypes were non-linearly associated with nad5Δ levels, most of the among-isolate phenotypic variation could be accounted for by phylogeographic clade membership. In particular, isolate-specific mitochondrial membrane potential was an excellent predictor of clade membership. We interpret this result in light of recent evidence for local adaptation to temperature in C. briggsae. Analysis of mitochondrial-nuclear hybrid strains provided support for both mtDNA and nuclear genetic variation as drivers of natural mitochondrial phenotype variation. This study demonstrates that multicellular eukaryotic species are capable of extensive natural variation in organellar phenotypes and highlights the potential of integrating evolutionary and cell biology perspectives.
Collapse
Affiliation(s)
- Kiley A. Hicks
- Biology Department, Portland State University, Portland, Oregon, United States of America
| | - Dana K. Howe
- Department of Zoology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - Aubrey Leung
- Department of Zoology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - Dee R. Denver
- Department of Zoology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - Suzanne Estes
- Biology Department, Portland State University, Portland, Oregon, United States of America
- * E-mail:
| |
Collapse
|
47
|
Goyal S, Balick DJ, Jerison ER, Neher RA, Shraiman BI, Desai MM. Dynamic mutation-selection balance as an evolutionary attractor. Genetics 2012; 191:1309-19. [PMID: 22661327 PMCID: PMC3416009 DOI: 10.1534/genetics.112.141291] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 05/24/2012] [Indexed: 11/18/2022] Open
Abstract
The vast majority of mutations are deleterious and are eliminated by purifying selection. Yet in finite asexual populations, purifying selection cannot completely prevent the accumulation of deleterious mutations due to Muller's ratchet: once lost by stochastic drift, the most-fit class of genotypes is lost forever. If deleterious mutations are weakly selected, Muller's ratchet can lead to a rapid degradation of population fitness. Evidently, the long-term stability of an asexual population requires an influx of beneficial mutations that continuously compensate for the accumulation of the weakly deleterious ones. Hence any stable evolutionary state of a population in a static environment must involve a dynamic mutation-selection balance, where accumulation of deleterious mutations is on average offset by the influx of beneficial mutations. We argue that such a state can exist for any population size N and mutation rate U and calculate the fraction of beneficial mutations, ε, that maintains the balanced state. We find that a surprisingly low ε suffices to achieve stability, even in small populations in the face of high mutation rates and weak selection, maintaining a well-adapted population in spite of Muller's ratchet. This may explain the maintenance of mitochondria and other asexual genomes.
Collapse
Affiliation(s)
| | - Daniel J. Balick
- Department of Physics, University of California, Santa Barbara, California 93106
| | - Elizabeth R. Jerison
- Departments of Organismic and Evolutionary Biology and of Physics, and Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, and
| | - Richard A. Neher
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Boris I. Shraiman
- Kavli Institute for Theoretical Physics and
- Department of Physics, University of California, Santa Barbara, California 93106
| | - Michael M. Desai
- Departments of Organismic and Evolutionary Biology and of Physics, and Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, and
| |
Collapse
|
48
|
Selfish little circles: transmission bias and evolution of large deletion-bearing mitochondrial DNA in Caenorhabditis briggsae nematodes. PLoS One 2012; 7:e41433. [PMID: 22859984 PMCID: PMC3409194 DOI: 10.1371/journal.pone.0041433] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 06/25/2012] [Indexed: 01/19/2023] Open
Abstract
Selfish DNA poses a significant challenge to genome stability and organismal fitness in diverse eukaryotic lineages. Although selfish mitochondrial DNA (mtDNA) has known associations with cytoplasmic male sterility in numerous gynodioecious plant species and is manifested as petite mutants in experimental yeast lab populations, examples of selfish mtDNA in animals are less common. We analyzed the inheritance and evolution of mitochondrial DNA bearing large heteroplasmic deletions including nad5 gene sequences (nad5Δ mtDNA), in the nematode Caenorhabditis briggsae. The deletion is widespread in C. briggsae natural populations and is associated with deleterious organismal effects. We studied the inheritance patterns of nad5Δ mtDNA using eight sets of C. briggsae mutation-accumulation (MA) lines, each initiated from a different natural strain progenitor and bottlenecked as single hermaphrodites across generations. We observed a consistent and strong drive toward higher levels of deletion-bearing molecules in the heteroplasmic pool of mtDNA after ten generations of bottlenecking. Our results demonstrate a uniform transmission bias whereby nad5Δ mtDNA accumulates to higher levels relative to intact mtDNA in multiple genetically diverse natural strains of C. briggsae. We calculated an average 1% per-generation transmission bias for deletion-bearing mtDNA relative to intact genomes. Our study, coupled with known deleterious phenotypes associated with high deletion levels, shows that nad5Δ mtDNA are selfish genetic elements that have evolved in natural populations of C. briggsae, offering a powerful new system to study selfish mtDNA dynamics in metazoans.
Collapse
|
49
|
Abstract
Evolution at high mutation rates is minimally affected by six processes: mutation-selection balance, error catastrophes, Muller's Ratchet, robustness and compensatory evolution, and clonal interference. Including all of these processes in a tractable, analytical model is difficult, but they can be captured in simulations that utilize realistic genotype-phenotype-fitness maps, as done here by modeling RNA folding. Subjecting finite, asexual populations to a range of mutation rates revealed simple criteria that predict when particular evolutionary processes are important. Populations were initiated with a genotype encoding the most fit phenotype. When purifying selection was strong relative to mutation, the initial genotype was replaced by one more mutationally robust, and the maximally fit phenotype was maintained in a mutation-selection balance where the deleterious mutation rate determined mean fitness. With weaker purifying selection, the most fit genotypes were lost. Although loss of the best genotype was ongoing and might have led to a progressive fitness decline, continual compensatory evolution led to an approximate fitness equilibration. Per total genomic mutation rate, mean fitness was similar for strong and weak purifying selection. These results represent a first step at separating interactions between evolutionary processes at high mutation rate, but additional theory is needed to interpret some outcomes.
Collapse
Affiliation(s)
- Thomas E Keller
- The Institute for Cellular and Molecular Biology, Center for Computational Biology and Bioinformatics, Section of Integrative Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
| | | | | |
Collapse
|
50
|
|