1
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Chen P, Zhang J. The loci of environmental adaptation in a model eukaryote. Nat Commun 2024; 15:5672. [PMID: 38971805 PMCID: PMC11227561 DOI: 10.1038/s41467-024-50002-y] [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: 12/19/2023] [Accepted: 06/25/2024] [Indexed: 07/08/2024] Open
Abstract
While the underlying genetic changes have been uncovered in some cases of adaptive evolution, the lack of a systematic study prevents a general understanding of the genomic basis of adaptation. For example, it is unclear whether protein-coding or noncoding mutations are more important to adaptive evolution and whether adaptations to different environments are brought by genetic changes distributed in diverse genes and biological processes or concentrated in a core set. We here perform laboratory evolution of 3360 Saccharomyces cerevisiae populations in 252 environments of varying levels of stress. We find the yeast adaptations to be primarily fueled by large-effect coding mutations overrepresented in a relatively small gene set, despite prevalent antagonistic pleiotropy across environments. Populations generally adapt faster in more stressful environments, partly because of greater benefits of the same mutations in more stressful environments. These and other findings from this model eukaryote help unravel the genomic principles of environmental adaptation.
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Affiliation(s)
- Piaopiao Chen
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA.
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2
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Plavskin Y, de Biase MS, Ziv N, Janská L, Zhu YO, Hall DW, Schwarz RF, Tranchina D, Siegal ML. Spontaneous single-nucleotide substitutions and microsatellite mutations have distinct distributions of fitness effects. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.04.547687. [PMID: 37461506 PMCID: PMC10349969 DOI: 10.1101/2023.07.04.547687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
The fitness effects of new mutations determine key properties of evolutionary processes. Beneficial mutations drive evolution, yet selection is also shaped by the frequency of small-effect deleterious mutations, whose combined effect can burden otherwise adaptive lineages and alter evolutionary trajectories and outcomes in clonally evolving organisms such as viruses, microbes, and tumors. The small effect sizes of these important mutations have made accurate measurements of their rates difficult. In microbes, assessing the effect of mutations on growth can be especially instructive, as this complex phenotype is closely linked to fitness in clonally evolving organisms. Here, we perform high-throughput time-lapse microscopy on cells from mutation-accumulation strains to precisely infer the distribution of mutational effects on growth rate in the budding yeast, Saccharomyces cerevisiae. We show that mutational effects on growth rate are overwhelmingly negative, highly skewed towards very small effect sizes, and frequent enough to suggest that deleterious hitchhikers may impose a significant burden on evolving lineages. By using lines that accumulated mutations in either wild-type or slippage repair-defective backgrounds, we further disentangle the effects of two common types of mutations, single-nucleotide substitutions and simple sequence repeat indels, and show that they have distinct effects on yeast growth rate. Although the average effect of a simple sequence repeat mutation is very small (~0.3%), many do alter growth rate, implying that this class of frequent mutations has an important evolutionary impact.
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3
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Ajay A, Begum T, Arya A, Kumar K, Ahmad S. Global and local genomic features together modulate the spontaneous single nucleotide mutation rate. Comput Biol Chem 2024; 112:108107. [PMID: 38875896 DOI: 10.1016/j.compbiolchem.2024.108107] [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: 08/10/2023] [Revised: 04/23/2024] [Accepted: 05/17/2024] [Indexed: 06/16/2024]
Abstract
Spontaneous mutations are evolutionary engines as they generate variants for the evolutionary downstream processes that give rise to speciation and adaptation. Single nucleotide mutations (SNM) are the most abundant type of mutations among them. Here, we perform a meta-analysis to quantify the influence of selected global genomic parameters (genome size, genomic GC content, genomic repeat fraction, number of coding genes, gene count, and strand bias in prokaryotes) and local genomic features (local GC content, repeat content, CpG content and the number of SNM at CpG islands) on spontaneous SNM rates across the tree of life (prokaryotes, unicellular eukaryotes, multicellular eukaryotes) using wild-type sequence data in two different taxon classification systems. We find that the spontaneous SNM rates in our data are correlated with many genomic features in prokaryotes and unicellular eukaryotes irrespective of their sample sizes. On the other hand, only the number of coding genes was correlated with the spontaneous SNM rates in multicellular eukaryotes primarily contributed by vertebrates data. Considering local features, we notice that local GC content and CpG content significantly were correlated with the spontaneous SNM rates in the unicellular eukaryotes, while local repeat fraction is an important feature in prokaryotes and certain specific uni- and multi-cellular eukaryotes. Such predictive features of the spontaneous SNM rates often support non-linear models as the best fit compared to the linear model. We also observe that the strand asymmetry in prokaryotes plays an important role in determining the spontaneous SNM rates but the SNM spectrum does not.
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Affiliation(s)
- Akash Ajay
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India; School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Tina Begum
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Ajay Arya
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Krishan Kumar
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Shandar Ahmad
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
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4
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Plyler ZE, McAtee CW, Hill AE, Crowley MR, Tindall JM, Tindall SR, Joshi D, Sorscher EJ. Relationships between genomic dissipation and de novo SNP evolution. PLoS One 2024; 19:e0303257. [PMID: 38753830 PMCID: PMC11098520 DOI: 10.1371/journal.pone.0303257] [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: 01/06/2024] [Accepted: 04/23/2024] [Indexed: 05/18/2024] Open
Abstract
Patterns of single nucleotide polymorphisms (SNPs) in eukaryotic DNA are traditionally attributed to selective pressure, drift, identity descent, or related factors-without accounting for ways in which bias during de novo SNP formation, itself, might contribute. A functional and phenotypic analysis based on evolutionary resilience of DNA points to decreased numbers of non-synonymous SNPs in human and other genomes, with a predominant component of SNP depletion in the human gene pool caused by robust preferences during de novo SNP formation (rather than selective constraint). Ramifications of these findings are broad, belie a number of concepts regarding human evolution, and point to a novel interpretation of evolving DNA across diverse species.
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Affiliation(s)
- Zackery E. Plyler
- Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Christopher W. McAtee
- Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Aubrey E. Hill
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Department of Computer and Information Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Michael R. Crowley
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | | | | | - Disha Joshi
- Emory University, Atlanta, Georgia, United States of America
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5
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Overton MS, Guy SE, Chen X, Martsul A, Carolino K, Akbari OS, Meyer JR, Kryazhimskiy S. Upper Bound on the Mutational Burden Imposed by a CRISPR-Cas9 Gene-Drive Element. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569142. [PMID: 38076841 PMCID: PMC10705488 DOI: 10.1101/2023.11.28.569142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
CRISPR-Cas9 gene drives (CCGDs) are powerful tools for genetic control of wild populations, useful for eradication of disease vectors, conservation of endangered species and other applications. However, Cas9 alone and in a complex with gRNA can cause double-stranded DNA breaks at off-target sites, which could increase the mutational load and lead to loss of heterozygosity (LOH). These undesired effects raise potential concerns about the long-term evolutionary safety of CCGDs, but the magnitude of these effects is unknown. To estimate how the presence of a CCGD or a Cas9 alone in the genome affects the rates of LOH events and de novo mutations, we carried out a mutation accumulation experiment in yeast Saccharomyces cerevisiae. Despite its substantial statistical power, our experiment revealed no detectable effect of CCGD or Cas9 alone on the genome-wide rates of mutations or LOH events, suggesting that these rates are affected by less than 30%. Nevertheless, we found that Cas9 caused a slight but significant shift towards more interstitial and fewer terminal LOH events, and the CCGD caused a significant difference in the distribution of LOH events on Chromosome V. Taken together, our results show that these genetic elements impose a weak and likely localized additional mutational burden in the yeast model. Although the mutagenic effects of CCGDs need to be further evaluated in other systems, our results suggest that the effect of CCGDs on off-target mutation rates and genetic diversity may be acceptable.
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Affiliation(s)
- Michael S. Overton
- Department of Ecology, Behavior and Evolution, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093
| | - Sean E. Guy
- Department of Ecology, Behavior and Evolution, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093
- Current address: Bionano Genomics, San Diego, CA 92121
| | - Xingsen Chen
- Department of Ecology, Behavior and Evolution, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093
- Current address: Department of Entomology, University of Arizona, Tucson, Arizona, USA
| | - Alena Martsul
- Department of Ecology, Behavior and Evolution, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093
- Current address: Illumina Inc., San Diego, CA 92122
| | - Krypton Carolino
- Department of Ecology, Behavior and Evolution, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093
| | - Omar S. Akbari
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Justin R. Meyer
- Department of Ecology, Behavior and Evolution, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093
| | - Sergey Kryazhimskiy
- Department of Ecology, Behavior and Evolution, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093
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6
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Li J, Stenberg S, Yue JX, Mikhalev E, Thompson D, Warringer J, Liti G. Genome instability footprint under rapamycin and hydroxyurea treatments. PLoS Genet 2023; 19:e1011012. [PMID: 37931001 PMCID: PMC10653606 DOI: 10.1371/journal.pgen.1011012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/16/2023] [Accepted: 10/10/2023] [Indexed: 11/08/2023] Open
Abstract
The mutational processes dictating the accumulation of mutations in genomes are shaped by genetic background, environment and their interactions. Accurate quantification of mutation rates and spectra under drugs has important implications in disease treatment. Here, we used whole-genome sequencing and time-resolved growth phenotyping of yeast mutation accumulation lines to give a detailed view of the mutagenic effects of rapamycin and hydroxyurea on the genome and cell growth. Mutation rates depended on the genetic backgrounds but were only marginally affected by rapamycin. As a remarkable exception, rapamycin treatment was associated with frequent chromosome XII amplifications, which compensated for rapamycin induced rDNA repeat contraction on this chromosome and served to maintain rDNA content homeostasis and fitness. In hydroxyurea, a wide range of mutation rates were elevated regardless of the genetic backgrounds, with a particularly high occurrence of aneuploidy that associated with dramatic fitness loss. Hydroxyurea also induced a high T-to-G and low C-to-A transversion rate that reversed the common G/C-to-A/T bias in yeast and gave rise to a broad range of structural variants, including mtDNA deletions. The hydroxyurea mutation footprint was consistent with the activation of error-prone DNA polymerase activities and non-homologues end joining repair pathways. Taken together, our study provides an in-depth view of mutation rates and signatures in rapamycin and hydroxyurea and their impact on cell fitness, which brings insights for assessing their chronic effects on genome integrity.
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Affiliation(s)
- Jing Li
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
- Université Côte d’Azur, CNRS, INSERM, IRCAN, Nice, France
| | - Simon Stenberg
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Jia-Xing Yue
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
- Université Côte d’Azur, CNRS, INSERM, IRCAN, Nice, France
| | | | - Dawn Thompson
- Ginkgo Bioworks, Boston, Massachusetts, United States of America
| | - Jonas Warringer
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Gianni Liti
- Université Côte d’Azur, CNRS, INSERM, IRCAN, Nice, France
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7
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Jung KW, Kwon S, Jung JH, Lim S, Bahn YS. Functional Characterization of DNA N-Glycosylase Ogg1 and Ntg1 in DNA Damage Stress of Cryptococcus neoformans. J Microbiol 2023; 61:981-992. [PMID: 38055144 DOI: 10.1007/s12275-023-00092-y] [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: 10/05/2023] [Accepted: 10/31/2023] [Indexed: 12/07/2023]
Abstract
Reactive oxygen species induce DNA strand breaks and DNA oxidation. DNA oxidation leads to DNA mismatches, resulting in mutations in the genome if not properly repaired. Homologous recombination (HR) and non-homologous end-joining (NHEJ) are required for DNA strand breaks, whereas the base excision repair system mainly repairs oxidized DNAs, such as 8-oxoguanine and thymine glycol, by cleaving the glycosidic bond, inserting correct nucleotides, and sealing the gap. Our previous studies revealed that the Rad53-Bdr1 pathway mainly controls DNA strand breaks through the regulation of HR- and NHEJ-related genes. However, the functional roles of genes involved in the base excision repair system remain elusive in Cryptococcus neoformans. In the present study, we identified OGG1 and NTG1 genes in the base excision repair system of C. neoformans, which are involved in DNA oxidation repair. The expression of OGG1 was induced in a Hog1-dependent manner under oxidative stress. On the other hand, the expression of NTG1 was strongly induced by DNA damage stress in a Rad53-independent manner. We demonstrated that the deletion of NTG1, but not OGG1, resulted in elevated susceptibility to DNA damage agents and oxidative stress inducers. Notably, the ntg1Δ mutant showed growth defects upon antifungal drug treatment. Although deletion of OGG1 or NTG1 did not increase mutation rates, the mutation profile of each ogg1Δ and ntg1Δ mutant was different from that of the wild-type strain. Taken together, we found that DNA N-glycosylase Ntg1 is required for oxidative DNA damage stress and antifungal drug resistance in C. neoformans.
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Affiliation(s)
- Kwang-Woo Jung
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea.
| | - Sunhak Kwon
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jong-Hyun Jung
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea
| | - Sangyong Lim
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea
- Department of Radiation Science, University of Science and Technology, Daejeon, 34113, Republic of Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
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8
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Liu H, Sun M, Zhang J. Genomic estimates of mutation and substitution rates contradict the evolutionary speed hypothesis of the latitudinal diversity gradient. Proc Biol Sci 2023; 290:20231787. [PMID: 37876195 PMCID: PMC10598419 DOI: 10.1098/rspb.2023.1787] [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: 08/08/2023] [Accepted: 09/26/2023] [Indexed: 10/26/2023] Open
Abstract
The latitudinal diversity gradient (LDG) refers to a decrease in biodiversity from the equator to the poles. The evolutionary speed hypothesis, backed by the metabolic theory of ecology, asserts that nucleotide mutation and substitution rates per site per year are higher and thereby speciation rates are higher at higher temperatures, generating the LDG. However, prior empirical investigations of the relationship between the temperature and mutation or substitution rate were based on a few genes and the results were mixed. We here revisit this relationship using genomic data. No significant correlation between the temperature and mutation rate is found in 13 prokaryotes or in 107 eukaryotes. An analysis of 234 diverse trios of bacterial taxa indicates that the synonymous substitution rate is not significantly associated with the growth temperature. The same data, however, reveal a significant negative association between the nonsynonymous substitution rate and temperature, which is explainable by a larger fraction of detrimental nonsynonymous mutations at higher temperatures due to a stronger demand for protein stability. We conclude that the evolutionary speed hypothesis of the LDG is unsupported by genomic data and advise that future mechanistic studies of the LDG should focus on other hypotheses.
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Affiliation(s)
- Haoxuan Liu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
- Center for Evolutionary & Organismal Biology and the Fourth Affiliated Hospital of Zhejiang University, Zhejiang University School of Medicine, Hangzhou 310058, People's Republic of China
| | - Mengyi Sun
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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9
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Sharp NP, Smith DR, Driscoll G, Sun K, Vickerman CM, Martin SCT. Contribution of Spontaneous Mutations to Quantitative and Molecular Variation at the Highly Repetitive rDNA Locus in Yeast. Genome Biol Evol 2023; 15:evad179. [PMID: 37847861 PMCID: PMC10581546 DOI: 10.1093/gbe/evad179] [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] [Accepted: 09/26/2023] [Indexed: 10/19/2023] Open
Abstract
The ribosomal DNA array in Saccharomyces cerevisiae consists of many tandem repeats whose copy number is believed to be functionally important but highly labile. Regulatory mechanisms have evolved to maintain copy number by directed mutation, but how spontaneous variation at this locus is generated and selected has not been well characterized. We applied a mutation accumulation approach to quantify the impacts of mutation and selection on this unique genomic feature across hundreds of mutant strains. We find that mutational variance for this trait is relatively high, and that unselected mutations elsewhere in the genome can disrupt copy number maintenance. In consequence, copy number generally declines gradually, consistent with a previously proposed model of rDNA maintenance where a downward mutational bias is normally compensated by mechanisms that increase copy number when it is low. This pattern holds across ploidy levels and strains in the standard lab environment but differs under some stressful conditions. We identify several alleles, gene categories, and genomic features that likely affect copy number, including aneuploidy for chromosome XII. Copy number change is associated with reduced growth in diploids, consistent with stabilizing selection. Levels of standing variation in copy number are well predicted by a balance between mutation and stabilizing selection, suggesting this trait is not subject to strong diversifying selection in the wild. The rate and spectrum of point mutations within the rDNA locus itself are distinct from the rest of the genome and predictive of polymorphism locations. Our findings help differentiate the roles of mutation and selection and indicate that spontaneous mutation patterns shape several aspects of ribosomal DNA evolution.
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Affiliation(s)
- Nathaniel P Sharp
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Denise R Smith
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Gregory Driscoll
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kexin Sun
- Present address: Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina, USA
| | | | - Sterling C T Martin
- Present address: Department of Biology, Washington University, St. Louis, Missouri, USA
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10
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Yu G, Liu Y, Li Z, Deng S, Wu Z, Zhang X, Chen W, Yang J, Chen X, Yang JR. Genome-wide probing of eukaryotic nascent RNA structure elucidates cotranscriptional folding and its antimutagenic effect. Nat Commun 2023; 14:5853. [PMID: 37730811 PMCID: PMC10511511 DOI: 10.1038/s41467-023-41550-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 09/08/2023] [Indexed: 09/22/2023] Open
Abstract
The transcriptional intermediates of RNAs fold into secondary structures with multiple regulatory roles, yet the details of such cotranscriptional RNA folding are largely unresolved in eukaryotes. Here, we present eSPET-seq (Structural Probing of Elongating Transcripts in eukaryotes), a method to assess the cotranscriptional RNA folding in Saccharomyces cerevisiae. Our study reveals pervasive structural transitions during cotranscriptional folding and overall structural similarities between nascent and mature RNAs. Furthermore, a combined analysis with genome-wide R-loop and mutation rate approximations provides quantitative evidence for the antimutator effect of nascent RNA folding through competitive inhibition of the R-loops, known to facilitate transcription-associated mutagenesis. Taken together, we present an experimental evaluation of cotranscriptional folding in eukaryotes and demonstrate the antimutator effect of nascent RNA folding. These results suggest genome-wide coupling between the processing and transmission of genetic information through RNA folding.
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Affiliation(s)
- Gongwang Yu
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Yao Liu
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Zizhang Li
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Shuyun Deng
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Zhuoxing Wu
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiaoyu Zhang
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Wenbo Chen
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Junnan Yang
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiaoshu Chen
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Key Laboratory of Tropical Disease Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jian-Rong Yang
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
- Department of Genetics and Biomedical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
- Key Laboratory of Tropical Disease Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China.
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11
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Avecilla G, Spealman P, Matthews J, Caudal E, Schacherer J, Gresham D. Copy number variation alters local and global mutational tolerance. Genome Res 2023; 33:1340-1353. [PMID: 37652668 PMCID: PMC10547251 DOI: 10.1101/gr.277625.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 07/07/2023] [Indexed: 09/02/2023]
Abstract
Copy number variants (CNVs), duplications and deletions of genomic sequences, contribute to evolutionary adaptation but can also confer deleterious effects and cause disease. Whereas the effects of amplifying individual genes or whole chromosomes (i.e., aneuploidy) have been studied extensively, much less is known about the genetic and functional effects of CNVs of differing sizes and structures. Here, we investigated Saccharomyces cerevisiae (yeast) strains that acquired adaptive CNVs of variable structures and copy numbers following experimental evolution in glutamine-limited chemostats. Although beneficial in the selective environment, CNVs result in decreased fitness compared with the euploid ancestor in rich media. We used transposon mutagenesis to investigate mutational tolerance and genome-wide genetic interactions in CNV strains. We find that CNVs increase mutational target size, confer increased mutational tolerance in amplified essential genes, and result in novel genetic interactions with unlinked genes. We validated a novel genetic interaction between different CNVs and BMH1 that was common to multiple strains. We also analyzed global gene expression and found that transcriptional dosage compensation does not affect most genes amplified by CNVs, although gene-specific transcriptional dosage compensation does occur for ∼12% of amplified genes. Furthermore, we find that CNV strains do not show previously described transcriptional signatures of aneuploidy. Our study reveals the extent to which local and global mutational tolerance is modified by CNVs with implications for genome evolution and CNV-associated diseases, such as cancer.
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Affiliation(s)
- Grace Avecilla
- Department of Biology, New York University, New York, New York 10003, USA
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
| | - Pieter Spealman
- Department of Biology, New York University, New York, New York 10003, USA
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
| | - Julia Matthews
- Department of Biology, New York University, New York, New York 10003, USA
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
| | - Elodie Caudal
- 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), 75231 Paris Cedex 05, France
| | - David Gresham
- Department of Biology, New York University, New York, New York 10003, USA;
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
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12
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Gifford DR, Berríos-Caro E, Joerres C, Suñé M, Forsyth JH, Bhattacharyya A, Galla T, Knight CG. Mutators can drive the evolution of multi-resistance to antibiotics. PLoS Genet 2023; 19:e1010791. [PMID: 37311005 DOI: 10.1371/journal.pgen.1010791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 05/18/2023] [Indexed: 06/15/2023] Open
Abstract
Antibiotic combination therapies are an approach used to counter the evolution of resistance; their purported benefit is they can stop the successive emergence of independent resistance mutations in the same genome. Here, we show that bacterial populations with 'mutators', organisms with defects in DNA repair, readily evolve resistance to combination antibiotic treatment when there is a delay in reaching inhibitory concentrations of antibiotic-under conditions where purely wild-type populations cannot. In populations of Escherichia coli subjected to combination treatment, we detected a diverse array of acquired mutations, including multiple alleles in the canonical targets of resistance for the two drugs, as well as mutations in multi-drug efflux pumps and genes involved in DNA replication and repair. Unexpectedly, mutators not only allowed multi-resistance to evolve under combination treatment where it was favoured, but also under single-drug treatments. Using simulations, we show that the increase in mutation rate of the two canonical resistance targets is sufficient to permit multi-resistance evolution in both single-drug and combination treatments. Under both conditions, the mutator allele swept to fixation through hitch-hiking with single-drug resistance, enabling subsequent resistance mutations to emerge. Ultimately, our results suggest that mutators may hinder the utility of combination therapy when mutators are present. Additionally, by raising the rates of genetic mutation, selection for multi-resistance may have the unwanted side-effect of increasing the potential to evolve resistance to future antibiotic treatments.
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Affiliation(s)
- Danna R Gifford
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Manchester, United Kingdom
| | - Ernesto Berríos-Caro
- Department of Physics and Astronomy, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Manchester, United Kingdom
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, Germany
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Christine Joerres
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Marc Suñé
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Jessica H Forsyth
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Anish Bhattacharyya
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Tobias Galla
- Department of Physics and Astronomy, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Manchester, United Kingdom
- Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat Illes Balears, Palma de Mallorca, Spain
| | - Christopher G Knight
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Manchester, United Kingdom
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13
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Longan ER, Fay JC. Experimental evolution of Saccharomyces uvarum at high temperature yields elevation of maximal growth temperature and loss of the mitochondrial genome. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000831. [PMID: 37334198 PMCID: PMC10276265 DOI: 10.17912/micropub.biology.000831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 05/19/2023] [Accepted: 05/30/2023] [Indexed: 06/20/2023]
Abstract
An organism's upper thermal tolerance is a major driver of its ecology and is a complex, polygenic trait. Given the wide variance in this critical phenotype across the tree of life, it is quite striking that this trait has not proven very evolutionarily labile in experimental evolution studies of microbes. In stark contrast to recent studies, William Henry Dallinger in the 1880s reported increasing the upper thermal limit of microbes he experimentally evolved by >40°C using a very gradual temperature ramping strategy. Using a selection scheme inspired by Dallinger, we sought to increase the upper thermal limit of Saccharomyces uvarum . This species has a maximum growth temperature of 34-35°C, considerably lower than S. cerevisiae . After 136 passages on solid plates at progressively higher temperatures, we recovered a clone that can grow at 36°C, a gain of ~1.5°C. Additionally, the evolved clone lost its mitochondrial genome and cannot respire. In contrast, an induced rho 0 derivative of the ancestor shows a decrease in thermotolerance. Also, incubation of the ancestor at 34°C for 5 days increased the frequency of petite mutants drastically compared to 22°C, supporting the notion that mutation pressure rather than selection drove loss of mtDNA in the evolved clone. These results demonstrate that S. uvarum 's upper thermal limit can be elevated slightly via experimental evolution and corroborate past observations in S. cerevisiae that high temperature selection schemes can inadvertently lead to production of the potentially undesirable respiratory incompetent phenotype in yeasts.
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Affiliation(s)
- Emery R. Longan
- University of Rochester, Department of Biology, Rochester, NY, 14620 USA
| | - Justin C. Fay
- University of Rochester, Department of Biology, Rochester, NY, 14620 USA
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14
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Krasovec M, Hoshino M, Zheng M, Lipinska AP, Coelho SM. Low Spontaneous Mutation Rate in Complex Multicellular Eukaryotes with a Haploid-Diploid Life Cycle. Mol Biol Evol 2023; 40:msad105. [PMID: 37140022 PMCID: PMC10254074 DOI: 10.1093/molbev/msad105] [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: 03/09/2023] [Revised: 04/22/2023] [Accepted: 05/01/2023] [Indexed: 05/05/2023] Open
Abstract
The spontaneous mutation rate µ is a crucial parameter to understand evolution and biodiversity. Mutation rates are highly variable across species, suggesting that µ is susceptible to selection and drift and that species life cycle and life history may impact its evolution. In particular, asexual reproduction and haploid selection are expected to affect the mutation rate, but very little empirical data are available to test this expectation. Here, we sequence 30 genomes of a parent-offspring pedigree in the model brown alga Ectocarpus sp.7, and 137 genomes of an interspecific cross of the closely related brown alga Scytosiphon to have access to the spontaneous mutation rate of representative organisms of a complex multicellular eukaryotic lineage outside animals and plants, and to evaluate the potential impact of life cycle on the mutation rate. Brown algae alternate between a haploid and a diploid stage, both multicellular and free living, and utilize both sexual and asexual reproduction. They are, therefore, excellent models to empirically test expectations of the effect of asexual reproduction and haploid selection on mutation rate evolution. We estimate that Ectocarpus has a base substitution rate of µbs = 4.07 × 10-10 per site per generation, whereas the Scytosiphon interspecific cross had µbs = 1.22 × 10-9. Overall, our estimations suggest that these brown algae, despite being multicellular complex eukaryotes, have unusually low mutation rates. In Ectocarpus, effective population size (Ne) could not entirely explain the low µbs. We propose that the haploid-diploid life cycle, combined with extensive asexual reproduction, may be additional key drivers of the mutation rate in these organisms.
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Affiliation(s)
- Marc Krasovec
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls-sur-Mer, France
| | - Masakazu Hoshino
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Min Zheng
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Agnieszka P Lipinska
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Susana M Coelho
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
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15
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Cano AV, Gitschlag BL, Rozhoňová H, Stoltzfus A, McCandlish DM, Payne JL. Mutation bias and the predictability of evolution. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220055. [PMID: 37004719 PMCID: PMC10067271 DOI: 10.1098/rstb.2022.0055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023] Open
Abstract
Predicting evolutionary outcomes is an important research goal in a diversity of contexts. The focus of evolutionary forecasting is usually on adaptive processes, and efforts to improve prediction typically focus on selection. However, adaptive processes often rely on new mutations, which can be strongly influenced by predictable biases in mutation. Here, we provide an overview of existing theory and evidence for such mutation-biased adaptation and consider the implications of these results for the problem of prediction, in regard to topics such as the evolution of infectious diseases, resistance to biochemical agents, as well as cancer and other kinds of somatic evolution. We argue that empirical knowledge of mutational biases is likely to improve in the near future, and that this knowledge is readily applicable to the challenges of short-term prediction. This article is part of the theme issue 'Interdisciplinary approaches to predicting evolutionary biology'.
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Affiliation(s)
- Alejandro V Cano
- Institute of Integrative Biology, ETH Zurich, 8092 Zurich, Switzerland
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Bryan L Gitschlag
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Hana Rozhoňová
- Institute of Integrative Biology, ETH Zurich, 8092 Zurich, Switzerland
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Arlin Stoltzfus
- Office of Data and Informatics, Material Measurement Laboratory, National Institute of Standards and Technology, Rockville, MD 20899, USA
- Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
| | - David M McCandlish
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Joshua L Payne
- Institute of Integrative Biology, ETH Zurich, 8092 Zurich, Switzerland
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
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16
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Tu X, Wang F, Liti G, Breitenbach M, Yue JX, Li J. Spontaneous Mutation Rates and Spectra of Respiratory-Deficient Yeast. Biomolecules 2023; 13:501. [PMID: 36979436 PMCID: PMC10046086 DOI: 10.3390/biom13030501] [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: 02/05/2023] [Revised: 03/05/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
The yeast petite mutant was first discovered in the yeast Saccharomyces cerevisiae, which shows growth stress due to defects in genes encoding the respiratory chain. In a previous study, we described that deletion of the nuclear-encoded gene MRPL25 leads to mitochondrial genome (mtDNA) loss and the petite phenotype, which can be rescued by acquiring ATP3 mutations. The mrpl25Δ strain showed an elevated SNV (single nucleotide variant) rate, suggesting genome instability occurred during the crisis of mtDNA loss. However, the genome-wide mutation landscape and mutational signatures of mitochondrial dysfunction are unknown. In this study we profiled the mutation spectra in yeast strains with the genotype combination of MRPL25 and ATP3 in their wildtype and mutated status, along with the wildtype and cytoplasmic petite rho0 strains as controls. In addition to the previously described elevated SNV rate, we found the INDEL (insertion/deletion) rate also increased in the mrpl25Δ strain, reinforcing the occurrence of genome instability. Notably, although both are petites, the mrpl25Δ and rho0 strains exhibited different INDEL rates and transition/transversion ratios, suggesting differences in the mutational signatures underlying these two types of petites. Interestingly, the petite-related mutagenesis effect disappeared when ATP3 suppressor mutations were acquired, suggesting a cost-effective mechanism for restoring both fitness and genome stability. Taken together, we present an unbiased genome-wide characterization of the mutation rates and spectra of yeast strains with respiratory deficiency, which provides valuable insights into the impact of respiratory deficiency on genome instability.
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Affiliation(s)
- Xinyu Tu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
| | - Fan Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
| | - Gianni Liti
- IRCAN, INSERM, Université Côte d’Azur, 06107 Nice, France
| | | | - Jia-Xing Yue
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
| | - Jing Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
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17
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Mutation Rate and Spectrum of the Silkworm in Normal and Temperature Stress Conditions. Genes (Basel) 2023; 14:genes14030649. [PMID: 36980921 PMCID: PMC10048334 DOI: 10.3390/genes14030649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/26/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Mutation rate is a crucial parameter in evolutionary genetics. However, the mutation rate of most species as well as the extent to which the environment can alter the genome of multicellular organisms remain poorly understood. Here, we used parents–progeny sequencing to investigate the mutation rate and spectrum of the domestic silkworm (Bombyx mori) among normal and two temperature stress conditions (32 °C and 0 °C). The rate of single-nucleotide mutations in the normal temperature rearing condition was 0.41 × 10−8 (95% confidence interval, 0.33 × 10−8–0.49 × 10−8) per site per generation, which was up to 1.5-fold higher than in four previously studied insects. Moreover, the mutation rates of the silkworm under the stresses are significantly higher than in normal conditions. Furthermore, the mutation rate varies less in gene regions under normal and temperature stresses. Together, these findings expand the known diversity of the mutation rate among eukaryotes but also have implications for evolutionary analysis that assumes a constant mutation rate among species and environments.
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18
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Zhang J. What Has Genomics Taught An Evolutionary Biologist? GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:1-12. [PMID: 36720382 PMCID: PMC10373158 DOI: 10.1016/j.gpb.2023.01.005] [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: 10/07/2022] [Revised: 01/06/2023] [Accepted: 01/19/2023] [Indexed: 01/30/2023]
Abstract
Genomics, an interdisciplinary field of biology on the structure, function, and evolution of genomes, has revolutionized many subdisciplines of life sciences, including my field of evolutionary biology, by supplying huge data, bringing high-throughput technologies, and offering a new approach to biology. In this review, I describe what I have learned from genomics and highlight the fundamental knowledge and mechanistic insights gained. I focus on three broad topics that are central to evolutionary biology and beyond-variation, interaction, and selection-and use primarily my own research and study subjects as examples. In the next decade or two, I expect that the most important contributions of genomics to evolutionary biology will be to provide genome sequences of nearly all known species on Earth, facilitate high-throughput phenotyping of natural variants and systematically constructed mutants for mapping genotype-phenotype-fitness landscapes, and assist the determination of causality in evolutionary processes using experimental evolution.
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Affiliation(s)
- Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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19
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Gelova SP, Doherty KN, Alasmar S, Chan K. Intrinsic base substitution patterns in diverse species reveal links to cancer and metabolism. Genetics 2022; 222:iyac144. [PMID: 36149294 PMCID: PMC9630983 DOI: 10.1093/genetics/iyac144] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/07/2022] [Indexed: 11/12/2022] Open
Abstract
Analyses of large-scale cancer sequencing data have revealed that mutagenic processes can create distinctive patterns of base substitutions, called mutational signatures. Interestingly, mutational patterns resembling some of these signatures can also be observed in normal cells. To determine whether similar patterns exist more generally, we analyzed large data sets of genetic variation, including mutations from 7 model species and single nucleotide polymorphisms in 42 species, totaling >1.9 billion variants. We found that base substitution patterns for most species closely match single base substitution (SBS) mutational signature 5 in the Catalog of Somatic Mutations in Cancer (COSMIC) database. SBS5 is ubiquitous in cancers and also present in normal human cells, suggesting that similar patterns of genetic variation across so many species are likely due to conserved biochemistry. We investigated the mechanistic origins of the SBS5-like mutational pattern in Saccharomyces cerevisiae, and show that translesion DNA synthesis and sugar metabolism are directly linked to this form of mutagenesis. We propose that conserved metabolic processes in cells are coupled to continuous generation of genetic variants, which can be acted upon by selection to drive the evolution of biological entities.
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Affiliation(s)
- Suzana P Gelova
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Kassidy N Doherty
- Biopharmaceutical Sciences Undergraduate Program, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Salma Alasmar
- Biopharmaceutical Sciences Undergraduate Program, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Kin Chan
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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20
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Hasan AR, Lachapelle J, El-Shawa SA, Potjewyd R, Ford SA, Ness RW. Salt stress alters the spectrum of de novo mutation available to selection during experimental adaptation of Chlamydomonas reinhardtii. Evolution 2022; 76:2450-2463. [PMID: 36036481 DOI: 10.1111/evo.14604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/12/2022] [Indexed: 01/22/2023]
Abstract
The genetic basis of adaptation is driven by both selection and the spectrum of available mutations. Given that the rate of mutation is not uniformly distributed across the genome and varies depending on the environment, understanding the signatures of selection across the genome is aided by first establishing what the expectations of genetic change are from mutation. To determine the interaction between salt stress, selection, and mutation across the genome, we compared mutations observed in a selection experiment for salt tolerance in Chlamydomonas reinhardtii to those observed in mutation accumulation (MA) experiments with and without salt exposure. MA lines evolved under salt stress had a single-nucleotide mutation rate of 1.1 × 10 - 9 $1.1 \times 10^{-9}$ , similar to that of MA lines under standard conditions ( 9.6 × 10 - 10 $9.6 \times 10^{-10}$ ). However, we found that salt stress led to an increased rate of indel mutations, but that many of these mutations were removed under selection. Finally, lines adapted to salt also showed excess clustering of mutations in the genome and the co-expression network, suggesting a role for positive selection in retaining mutations in particular compartments of the genome during the evolution of salt tolerance. Our study shows that characterizing mutation rates and spectra expected under stress helps disentangle the effects of environment and selection during adaptation.
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Affiliation(s)
- Ahmed R Hasan
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada.,Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Josianne Lachapelle
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Sara A El-Shawa
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada.,Department of Mathematical and Computational Sciences, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Roman Potjewyd
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Scott A Ford
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Rob W Ness
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada.,Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
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21
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Melde RH, Bao K, Sharp NP. Recent insights into the evolution of mutation rates in yeast. Curr Opin Genet Dev 2022; 76:101953. [PMID: 35834945 PMCID: PMC9491374 DOI: 10.1016/j.gde.2022.101953] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 05/25/2022] [Accepted: 06/13/2022] [Indexed: 02/08/2023]
Abstract
Mutation is the origin of all genetic variation, good and bad. The mutation process can evolve in response to mutations, positive or negative selection, and genetic drift, but how these forces contribute to mutation-rate variation is an unsolved problem at the heart of genetics research. Mutations can be challenging to measure, but genome sequencing and other tools have allowed for the collection of larger and more detailed datasets, particularly in the yeast-model system. We review key hypotheses for the evolution of mutation rates and describe recent advances in understanding variation in mutational properties within and among yeast species. The multidimensional spectrum of mutations is increasingly recognized as holding valuable clues about how this important process evolves.
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Affiliation(s)
- Robert H Melde
- Department of Genetics, University of Wisconsin-Madison, USA.
| | - Kevin Bao
- Department of Genetics, University of Wisconsin-Madison, USA
| | - Nathaniel P Sharp
- Department of Genetics, University of Wisconsin-Madison, USA. https://twitter.com/@sharpnath
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22
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Mahilkar A, Raj N, Kemkar S, Saini S. Selection in a growing colony biases results of mutation accumulation experiments. Sci Rep 2022; 12:15470. [PMID: 36104390 PMCID: PMC9475022 DOI: 10.1038/s41598-022-19928-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 09/06/2022] [Indexed: 11/11/2022] Open
Abstract
Mutations provide the raw material for natural selection to act. Therefore, understanding the variety and relative frequency of different type of mutations is critical to understanding the nature of genetic diversity in a population. Mutation accumulation (MA) experiments have been used in this context to estimate parameters defining mutation rates, distribution of fitness effects (DFE), and spectrum of mutations. MA experiments can be performed with different effective population sizes. In MA experiments with bacteria, a single founder is grown to a size of a colony (~ 108). It is assumed that natural selection plays a minimal role in dictating the dynamics of colony growth. In this work, we simulate colony growth via a mathematical model, and use our model to mimic an MA experiment. We demonstrate that selection ensures that, in an MA experiment, fraction of all mutations that are beneficial is over-represented by a factor of almost two, and that the distribution of fitness effects of beneficial and deleterious mutations are inaccurately captured in an MA experiment. Given this, the estimate of mutation rates from MA experiments is non-trivial. We then perform an MA experiment with 160 lines of E. coli, and show that due to the effect of selection in a growing colony, the size and sector of a colony from which the experiment is propagated impacts the results. Overall, we demonstrate that the results of MA experiments need to be revisited taking into account the action of selection in a growing colony.
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Affiliation(s)
- Anjali Mahilkar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Namratha Raj
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Sharvari Kemkar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Supreet Saini
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
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23
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Rapid evolution of mutation rate and spectrum in response to environmental and population-genetic challenges. Nat Commun 2022; 13:4752. [PMID: 35963846 PMCID: PMC9376063 DOI: 10.1038/s41467-022-32353-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 07/26/2022] [Indexed: 11/15/2022] Open
Abstract
Ecological and demographic factors can significantly shape the evolution of microbial populations both directly and indirectly, as when changes in the effective population size affect the efficiency of natural selection on the mutation rate. However, it remains unclear how rapidly the mutation-rate responds evolutionarily to the entanglement of ecological and population-genetic factors over time. Here, we directly assess the mutation rate and spectrum of Escherichia coli clones isolated from populations evolving in response to 1000 days of different transfer volumes and resource-replenishment intervals. The evolution of mutation rates proceeded rapidly in response to demographic and/or environmental changes, with substantial bidirectional shifts observed as early as 59 generations. These results highlight the remarkable rapidity by which mutation rates are shaped in asexual lineages in response to environmental and population-genetic forces, and are broadly consistent with the drift-barrier hypothesis for the evolution of mutation rates, while also highlighting situations in which mutator genotypes may be promoted by positive selection. How rapidly the mutation rate responds evolutionarily to ecological and population-genetic factors over time is unclear. Here, the authors show that the evolution of mutation rates in E. coli proceeds rapidly in response to these factors with substantial bidirectional shifts.
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24
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Abstract
A study of the plant Arabidopsis thaliana detected lower mutation rates in genomic regions where mutations are more likely to be deleterious, challenging the principle that mutagenesis is blind to its consequence. To examine the generality of this finding, we analyze large mutational data from baker's yeast and humans. The yeast data do not exhibit this trend, whereas the human data show an opposite trend that disappears upon the control of potential confounders. We find that the Arabidopsis study identified substantially more mutations than reported in the original data-generating studies and expected from Arabidopsis' mutation rate. These extra mutations are enriched in polynucleotide tracts and have relatively low sequencing qualities so are likely sequencing errors. Furthermore, the polynucleotide “mutations” can produce the purported mutational trend in Arabidopsis. Together, our results do not support lower mutagenesis of genomic regions of stronger selective constraints in the plant, fungal, and animal models examined.
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Affiliation(s)
- Haoxuan Liu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.,Evolutionary and Organismal Biology Research Center, School of Medicine, Zhejiang University, Hangzhou, 310000, China
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
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25
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Bao K, Melde RH, Sharp NP. Are mutations usually deleterious? A perspective on the fitness effects of mutation accumulation. Evol Ecol 2022; 36:753-766. [DOI: 10.1007/s10682-022-10187-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Selection signatures in melanocortin-1 receptor gene of turkeys (Meleagris gallopavo) raised in hot humid tropics. Trop Anim Health Prod 2022; 54:183. [PMID: 35525911 DOI: 10.1007/s11250-022-03185-9] [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: 08/22/2021] [Accepted: 04/28/2022] [Indexed: 10/18/2022]
Abstract
Feather colours are used by avian species for defense, adaptation and signaling. Melanocortin-1 receptor (MC1R) gene is one of the genes responsible for feather colour. This study identified selection signatures in MC1R gene of Nigerian indigenous turkeys (NIT) using British United turkeys (BUT) as control breed to investigate the evolutionary processes that have shaped NIT with various feather colours. Complete MC1R gene of 146 NIT (76 males and 70 females) and 32 BUT (18 males and 14 females) were sequenced. Transition/transversion and codon usage biases were predicted using MEGA v6 software. The selective force acting on the gene was predicted using HyPhy software. The FST values were estimated using Arlequin v3.5. The highest transition/transversion bias was predicted for white BUT (1.00) while the lowest was predicted for black NIT (0.50). Negative dN-dS values, indicative of purifying selection, were observed in MC1R gene of all the turkeys. The highest pairwise FST was observed between the MC1R gene of white BUT and black NIT while the least was observed between lavender NIT and white NIT. No recombination event was observed in black NIT and white BUT. The relative synonymous codon usage was the same among different colours for some codons. Presence of purifying selection in MC1R gene of all the turkeys with different feather colours confirms that the gene plays role in many biological processes such as feather colouration, behaviour, pain perception, immunity, growth and adaptation. The results also suggested that the genetic mechanisms generating different feather colours in turkeys are conserved.
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27
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Avecilla G, Chuong JN, Li F, Sherlock G, Gresham D, Ram Y. Neural networks enable efficient and accurate simulation-based inference of evolutionary parameters from adaptation dynamics. PLoS Biol 2022; 20:e3001633. [PMID: 35622868 PMCID: PMC9140244 DOI: 10.1371/journal.pbio.3001633] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 04/14/2022] [Indexed: 11/24/2022] Open
Abstract
The rate of adaptive evolution depends on the rate at which beneficial mutations are introduced into a population and the fitness effects of those mutations. The rate of beneficial mutations and their expected fitness effects is often difficult to empirically quantify. As these 2 parameters determine the pace of evolutionary change in a population, the dynamics of adaptive evolution may enable inference of their values. Copy number variants (CNVs) are a pervasive source of heritable variation that can facilitate rapid adaptive evolution. Previously, we developed a locus-specific fluorescent CNV reporter to quantify CNV dynamics in evolving populations maintained in nutrient-limiting conditions using chemostats. Here, we use CNV adaptation dynamics to estimate the rate at which beneficial CNVs are introduced through de novo mutation and their fitness effects using simulation-based likelihood-free inference approaches. We tested the suitability of 2 evolutionary models: a standard Wright-Fisher model and a chemostat model. We evaluated 2 likelihood-free inference algorithms: the well-established Approximate Bayesian Computation with Sequential Monte Carlo (ABC-SMC) algorithm, and the recently developed Neural Posterior Estimation (NPE) algorithm, which applies an artificial neural network to directly estimate the posterior distribution. By systematically evaluating the suitability of different inference methods and models, we show that NPE has several advantages over ABC-SMC and that a Wright-Fisher evolutionary model suffices in most cases. Using our validated inference framework, we estimate the CNV formation rate at the GAP1 locus in the yeast Saccharomyces cerevisiae to be 10-4.7 to 10-4 CNVs per cell division and a fitness coefficient of 0.04 to 0.1 per generation for GAP1 CNVs in glutamine-limited chemostats. We experimentally validated our inference-based estimates using 2 distinct experimental methods-barcode lineage tracking and pairwise fitness assays-which provide independent confirmation of the accuracy of our approach. Our results are consistent with a beneficial CNV supply rate that is 10-fold greater than the estimated rates of beneficial single-nucleotide mutations, explaining the outsized importance of CNVs in rapid adaptive evolution. More generally, our study demonstrates the utility of novel neural network-based likelihood-free inference methods for inferring the rates and effects of evolutionary processes from empirical data with possible applications ranging from tumor to viral evolution.
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Affiliation(s)
- Grace Avecilla
- Department of Biology, New York University, New York, New York, United States of America
- Center for Genomics and Systems Biology, New York University, New York, New York, United States of America
| | - Julie N. Chuong
- Department of Biology, New York University, New York, New York, United States of America
- Center for Genomics and Systems Biology, New York University, New York, New York, United States of America
| | - Fangfei Li
- Department of Genetics, Stanford University, California, Stanford, United States of America
| | - Gavin Sherlock
- Department of Genetics, Stanford University, California, Stanford, United States of America
| | - David Gresham
- Department of Biology, New York University, New York, New York, United States of America
- Center for Genomics and Systems Biology, New York University, New York, New York, United States of America
| | - Yoav Ram
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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28
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Sandell L, Sharp NP. Fitness Effects of Mutations: An Assessment of PROVEAN Predictions Using Mutation Accumulation Data. Genome Biol Evol 2022; 14:evac004. [PMID: 35038732 PMCID: PMC8790079 DOI: 10.1093/gbe/evac004] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2021] [Indexed: 11/14/2022] Open
Abstract
Predicting fitness in natural populations is a major challenge in biology. It may be possible to leverage fast-accumulating genomic data sets to infer the fitness effects of mutant alleles, allowing evolutionary questions to be addressed in any organism. In this paper, we investigate the utility of one such tool, called PROVEAN. This program compares a query sequence with existing data to provide an alignment-based score for any protein variant, with scores categorized as neutral or deleterious based on a pre-set threshold. PROVEAN has been used widely in evolutionary studies, for example, to estimate mutation load in natural populations, but has not been formally tested as a predictor of aggregate mutational effects on fitness. Using three large published data sets on the genome sequences of laboratory mutation accumulation lines, we assessed how well PROVEAN predicted the actual fitness patterns observed, relative to other metrics. In most cases, we find that a simple count of the total number of mutant proteins is a better predictor of fitness than the number of proteins with variants scored as deleterious by PROVEAN. We also find that the sum of all mutant protein scores explains variation in fitness better than the number of mutant proteins in one of the data sets. We discuss the implications of these results for studies of populations in the wild.
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Affiliation(s)
- Linnea Sandell
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Systematic Biology, Department of Organismal Biology, Uppsala University, Sweden
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29
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Fijarczyk A, Hénault M, Marsit S, Charron G, Landry CR. Heterogeneous Mutation Rates and Spectra in Yeast Hybrids. Genome Biol Evol 2021; 13:6462191. [PMID: 34908117 PMCID: PMC8715523 DOI: 10.1093/gbe/evab282] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2021] [Indexed: 12/11/2022] Open
Abstract
Mutation rates and spectra vary between species and among populations. Hybridization can contribute to this variation, but its role remains poorly understood. Estimating mutation rates requires controlled conditions where the effect of natural selection can be minimized. One way to achieve this is through mutation accumulation experiments coupled with genome sequencing. Here, we investigate 400 mutation accumulation lines initiated from 11 genotypes spanning intralineage, interlineage, and interspecific crosses of the yeasts Saccharomyces paradoxus and S. cerevisiae and propagated for 770 generations. We find significant differences in mutation rates and spectra among crosses, which are not related to the level of divergence of parental strains but are specific to some genotype combinations. Differences in number of generations and departures from neutrality play a minor role, whereas polyploidy and loss of heterozygosity impact mutation rates in some of the hybrid crosses in an opposite way.
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Affiliation(s)
- Anna Fijarczyk
- Département de Biologie, Université Laval, Québec, Québec, Canada.,Institut de Biologie Intégrative et des Systemes (IBIS), Université Laval, Québec, Québec, Canada.,Département de Biochimie, Microbiologie et Bioinformatique, Université Laval, Québec, Québec, Canada.,PROTEO, Le Réseau Québécois de Recherche sur la Fonction, La Structure et L'Ingénierie des Protéines, Université Laval, Québec, Québec, Canada.,Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, Québec, Canada
| | - Mathieu Hénault
- Département de Biologie, Université Laval, Québec, Québec, Canada.,Institut de Biologie Intégrative et des Systemes (IBIS), Université Laval, Québec, Québec, Canada.,Département de Biochimie, Microbiologie et Bioinformatique, Université Laval, Québec, Québec, Canada.,PROTEO, Le Réseau Québécois de Recherche sur la Fonction, La Structure et L'Ingénierie des Protéines, Université Laval, Québec, Québec, Canada.,Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, Québec, Canada
| | - Souhir Marsit
- Département de Biologie, Université Laval, Québec, Québec, Canada.,Institut de Biologie Intégrative et des Systemes (IBIS), Université Laval, Québec, Québec, Canada.,Département de Biochimie, Microbiologie et Bioinformatique, Université Laval, Québec, Québec, Canada.,PROTEO, Le Réseau Québécois de Recherche sur la Fonction, La Structure et L'Ingénierie des Protéines, Université Laval, Québec, Québec, Canada.,Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, Québec, Canada
| | - Guillaume Charron
- Département de Biologie, Université Laval, Québec, Québec, Canada.,Institut de Biologie Intégrative et des Systemes (IBIS), Université Laval, Québec, Québec, Canada.,Département de Biochimie, Microbiologie et Bioinformatique, Université Laval, Québec, Québec, Canada.,PROTEO, Le Réseau Québécois de Recherche sur la Fonction, La Structure et L'Ingénierie des Protéines, Université Laval, Québec, Québec, Canada.,Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, Québec, Canada
| | - Christian R Landry
- Département de Biologie, Université Laval, Québec, Québec, Canada.,Institut de Biologie Intégrative et des Systemes (IBIS), Université Laval, Québec, Québec, Canada.,Département de Biochimie, Microbiologie et Bioinformatique, Université Laval, Québec, Québec, Canada.,PROTEO, Le Réseau Québécois de Recherche sur la Fonction, La Structure et L'Ingénierie des Protéines, Université Laval, Québec, Québec, Canada.,Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, Québec, Canada
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30
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Yuan H, Chen W, Chen Y, Wang L, Zhang C, Deng W, Zhang L, Liu G, Shen C, Lou K, Wang S. Isolation and characterization of yeast for the production of rice wine with low fusel alcohol content. PLoS One 2021; 16:e0260024. [PMID: 34788334 PMCID: PMC8598244 DOI: 10.1371/journal.pone.0260024] [Citation(s) in RCA: 7] [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: 06/03/2021] [Accepted: 10/31/2021] [Indexed: 11/24/2022] Open
Abstract
Fusel alcohols (FAs) are a type of flavor compound found in rice wine. An overly high FA content not only leads to spicy, bitter, and astringent taste but also has side effects. Therefore, screening for yeast that produce low FA contents has attracted much attention. Thirty-two yeast strains were isolated from fermenting material during Luzhou-flavor liquor production in this study. Strain YB-12 was selected as a suitable candidate for rice wine production. The strain was identified as a member of the genus Meyerozyma based on phylogenetic analysis using 26S rDNA gene sequences. The ability of strain YB-12 to produce ethanol was similar to that of Saccharomyces cerevisiae NRRL Y-567, while isobutanol and isoamyl alcohol production was only 53.96% and 50.23%, respectively, of that of NRRL Y-567. The FA yield of rice wine produced with strain YB-12 was reduced to 51.85% in a 20 L fermenter. These results demonstrate that strain YB-12 presents promising characteristics for use in the production of rice wine with a potentially low content of FAs.
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Affiliation(s)
- Huawei Yuan
- Faculty of Quality Management and Inspection & Quarantine, Yibin University, Yibin, Sichuan, China
- Solid-state Fermentation Resource Utilization Key Laboratory of Sichuan Province, Yibin, Sichuan, China
| | - Wenhao Chen
- Solid-state Fermentation Resource Utilization Key Laboratory of Sichuan Province, Yibin, Sichuan, China
- Faculty of Agriculture & Forestry and Food Engineering, Yibin University, Yibin, Sichuan, China
| | - Yuanlin Chen
- Faculty of Quality Management and Inspection & Quarantine, Yibin University, Yibin, Sichuan, China
| | - Lian Wang
- Faculty of Quality Management and Inspection & Quarantine, Yibin University, Yibin, Sichuan, China
| | - Chao Zhang
- Solid-state Fermentation Resource Utilization Key Laboratory of Sichuan Province, Yibin, Sichuan, China
- Faculty of Agriculture & Forestry and Food Engineering, Yibin University, Yibin, Sichuan, China
| | - Wuyuan Deng
- Solid-state Fermentation Resource Utilization Key Laboratory of Sichuan Province, Yibin, Sichuan, China
- Faculty of Agriculture & Forestry and Food Engineering, Yibin University, Yibin, Sichuan, China
| | - Liqiang Zhang
- Luzhou Laojiao Co., Ltd. Luzhou, Luzhou, Sichuan, China
- National Engineering Technology Research Center of Solid-state Brewing, Luzhou, Sichuan, China
| | - Guangqian Liu
- Luzhou Laojiao Co., Ltd. Luzhou, Luzhou, Sichuan, China
- National Engineering Technology Research Center of Solid-state Brewing, Luzhou, Sichuan, China
| | - Caihong Shen
- Luzhou Laojiao Co., Ltd. Luzhou, Luzhou, Sichuan, China
- National Engineering Technology Research Center of Solid-state Brewing, Luzhou, Sichuan, China
| | - Kai Lou
- Faculty of Quality Management and Inspection & Quarantine, Yibin University, Yibin, Sichuan, China
- * E-mail: (KL); (SW)
| | - Songtao Wang
- Luzhou Laojiao Co., Ltd. Luzhou, Luzhou, Sichuan, China
- National Engineering Technology Research Center of Solid-state Brewing, Luzhou, Sichuan, China
- * E-mail: (KL); (SW)
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31
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Papaioannou IA, Dutreux F, Peltier FA, Maekawa H, Delhomme N, Bardhan A, Friedrich A, Schacherer J, Knop M. Sex without crossing over in the yeast Saccharomycodes ludwigii. Genome Biol 2021; 22:303. [PMID: 34732243 PMCID: PMC8567612 DOI: 10.1186/s13059-021-02521-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 10/20/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Intermixing of genomes through meiotic reassortment and recombination of homologous chromosomes is a unifying theme of sexual reproduction in eukaryotic organisms and is considered crucial for their adaptive evolution. Previous studies of the budding yeast species Saccharomycodes ludwigii suggested that meiotic crossing over might be absent from its sexual life cycle, which is predominated by fertilization within the meiotic tetrad. RESULTS We demonstrate that recombination is extremely suppressed during meiosis in Sd. ludwigii. DNA double-strand break formation by the conserved transesterase Spo11, processing and repair involving interhomolog interactions are required for normal meiosis but do not lead to crossing over. Although the species has retained an intact meiotic gene repertoire, genetic and population analyses suggest the exceptionally rare occurrence of meiotic crossovers in its genome. A strong AT bias of spontaneous mutations and the absence of recombination are likely responsible for its unusually low genomic GC level. CONCLUSIONS Sd. ludwigii has followed a unique evolutionary trajectory that possibly derives fitness benefits from the combination of frequent mating between products of the same meiotic event with the extreme suppression of meiotic recombination. This life style ensures preservation of heterozygosity throughout its genome and may enable the species to adapt to its environment and survive with only minimal levels of rare meiotic recombination. We propose Sd. ludwigii as an excellent natural forum for the study of genome evolution and recombination rates.
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Affiliation(s)
| | - Fabien Dutreux
- Université de Strasbourg, CNRS, GMGM UMR 7156, Strasbourg, France
| | - France A. Peltier
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany
| | - Hiromi Maekawa
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany
- Current affiliation: Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Nicolas Delhomme
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Amit Bardhan
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany
| | - Anne Friedrich
- 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
| | - Michael Knop
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany
- German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
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32
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Leehan JD, Nicholson WL. The Spectrum of Spontaneous Rifampin Resistance Mutations in the Bacillus subtilis rpoB Gene Depends on the Growth Environment. Appl Environ Microbiol 2021; 87:e0123721. [PMID: 34495706 PMCID: PMC8552901 DOI: 10.1128/aem.01237-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/01/2021] [Indexed: 11/20/2022] Open
Abstract
Results from previous investigations into spontaneous rifampin resistance (Rifr) mutations in the Bacillus subtilis rpoB gene suggested that the spectrum of mutations depends on the growth environment. However, these studies were limited by low sample numbers, allowing for the potential distortion of the data by the presence of "jackpot" mutations that may have arisen early in the growth of a population. Here, we addressed this issue by performing fluctuation analyses to assess both the rate and spectrum of Rifr mutations in two distinct media: LB, a complete laboratory medium, and SMMAsn, a minimal medium utilizing l-asparagine as the sole carbon source. We cultivated 60 separate populations under each growth condition and determined the mutation rate to Rifr to be slightly but significantly higher in LB cultures. We then sequenced the relevant regions of rpoB to map the spectrum of Rifr mutations under each growth condition. We found a distinct spectrum of mutations in each medium; LB cultures were dominated by the H482Y mutation (27/53 or 51%), whereas SMMAsn cultures were dominated by the S487L mutation (24/51 or 47%). Furthermore, we found through competition experiments that the relative fitness of the S487L mutant was significantly higher in SMMAsn than in LB medium. We therefore conclude that both the spectrum of Rifr mutations in the B. subtilis rpoB gene and the fitness of resulting mutants are influenced by the growth environment. IMPORTANCE The rpoB gene encodes the beta subunit of RNA polymerase, and mutations in rpoB are key determinants of resistance to the clinically important antibiotic rifampin. We show here that the spectrum of mutations in Bacillus subtilis rpoB depends on the medium in which the cells are cultivated. The results show that the growth environment not only plays a role in natural selection and fitness but also influences the probability of mutation at particular bases within the target gene.
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Affiliation(s)
- Joss D. Leehan
- Department of Microbiology and Cell Science, University of Florida, Merritt Island, Florida, USA
| | - Wayne L. Nicholson
- Department of Microbiology and Cell Science, University of Florida, Merritt Island, Florida, USA
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33
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Epigenetic modifications affect the rate of spontaneous mutations in a pathogenic fungus. Nat Commun 2021; 12:5869. [PMID: 34620872 PMCID: PMC8497519 DOI: 10.1038/s41467-021-26108-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/17/2021] [Indexed: 12/17/2022] Open
Abstract
Mutations are the source of genetic variation and the substrate for evolution. Genome-wide mutation rates appear to be affected by selection and are probably adaptive. Mutation rates are also known to vary along genomes, possibly in response to epigenetic modifications, but causality is only assumed. In this study we determine the direct impact of epigenetic modifications and temperature stress on mitotic mutation rates in a fungal pathogen using a mutation accumulation approach. Deletion mutants lacking epigenetic modifications confirm that histone mark H3K27me3 increases whereas H3K9me3 decreases the mutation rate. Furthermore, cytosine methylation in transposable elements (TE) increases the mutation rate 15-fold resulting in significantly less TE mobilization. Also accessory chromosomes have significantly higher mutation rates. Finally, we find that temperature stress substantially elevates the mutation rate. Taken together, we find that epigenetic modifications and environmental conditions modify the rate and the location of spontaneous mutations in the genome and alter its evolutionary trajectory.
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34
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Jiang P, Ollodart AR, Sudhesh V, Herr AJ, Dunham MJ, Harris K. A modified fluctuation assay reveals a natural mutator phenotype that drives mutation spectrum variation within Saccharomyces cerevisiae. eLife 2021; 10:68285. [PMID: 34523420 PMCID: PMC8497059 DOI: 10.7554/elife.68285] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 09/14/2021] [Indexed: 12/23/2022] Open
Abstract
Although studies of Saccharomyces cerevisiae have provided many insights into mutagenesis and DNA repair, most of this work has focused on a few laboratory strains. Much less is known about the phenotypic effects of natural variation within S. cerevisiae’s DNA repair pathways. Here, we use natural polymorphisms to detect historical mutation spectrum differences among several wild and domesticated S. cerevisiae strains. To determine whether these differences are likely caused by genetic mutation rate modifiers, we use a modified fluctuation assay with a CAN1 reporter to measure de novo mutation rates and spectra in 16 of the analyzed strains. We measure a 10-fold range of mutation rates and identify two strains with distinctive mutation spectra. These strains, known as AEQ and AAR, come from the panel’s ‘Mosaic beer’ clade and share an enrichment for C > A mutations that is also observed in rare variation segregating throughout the genomes of several Mosaic beer and Mixed origin strains. Both AEQ and AAR are haploid derivatives of the diploid natural isolate CBS 1782, whose rare polymorphisms are enriched for C > A as well, suggesting that the underlying mutator allele is likely active in nature. We use a plasmid complementation test to show that AAR and AEQ share a mutator allele in the DNA repair gene OGG1, which excises 8-oxoguanine lesions that can cause C > A mutations if left unrepaired.
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Affiliation(s)
- Pengyao Jiang
- Department of Genome Sciences, University of Washington, Seattle, United States
| | - Anja R Ollodart
- Department of Genome Sciences, University of Washington, Seattle, United States.,Molecular and Cellular Biology Program, University of Washington, Seattle, United States
| | - Vidha Sudhesh
- Department of Genome Sciences, University of Washington, Seattle, United States
| | - Alan J Herr
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, United States
| | - Maitreya J Dunham
- Department of Genome Sciences, University of Washington, Seattle, United States
| | - Kelley Harris
- Department of Genome Sciences, University of Washington, Seattle, United States.,Department of Computational Biology, Fred Hutchinson Cancer Research Center, Seattle, United States
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35
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Loewenthal G, Rapoport D, Avram O, Moshe A, Wygoda E, Itzkovitch A, Israeli O, Azouri D, Cartwright RA, Mayrose I, Pupko T. A probabilistic model for indel evolution: differentiating insertions from deletions. Mol Biol Evol 2021; 38:5769-5781. [PMID: 34469521 PMCID: PMC8662616 DOI: 10.1093/molbev/msab266] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Insertions and deletions (indels) are common molecular evolutionary events. However, probabilistic models for indel evolution are under-developed due to their computational complexity. Here, we introduce several improvements to indel modeling: 1) While previous models for indel evolution assumed that the rates and length distributions of insertions and deletions are equal, here we propose a richer model that explicitly distinguishes between the two; 2) we introduce numerous summary statistics that allow approximate Bayesian computation-based parameter estimation; 3) we develop a method to correct for biases introduced by alignment programs, when inferring indel parameters from empirical data sets; and 4) using a model-selection scheme, we test whether the richer model better fits biological data compared with the simpler model. Our analyses suggest that both our inference scheme and the model-selection procedure achieve high accuracy on simulated data. We further demonstrate that our proposed richer model better fits a large number of empirical data sets and that, for the majority of these data sets, the deletion rate is higher than the insertion rate.
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Affiliation(s)
- Gil Loewenthal
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Dana Rapoport
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Oren Avram
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Asher Moshe
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Elya Wygoda
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Alon Itzkovitch
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Omer Israeli
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Dana Azouri
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.,School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Reed A Cartwright
- The Biodesign Institute, Arizona State University, Tempe, Arizona, USA.,School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Itay Mayrose
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tal Pupko
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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36
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López-Cortegano E, Craig RJ, Chebib J, Samuels T, Morgan AD, Kraemer SA, Böndel KB, Ness RW, Colegrave N, Keightley PD. De Novo Mutation Rate Variation and Its Determinants in Chlamydomonas. Mol Biol Evol 2021; 38:3709-3723. [PMID: 33950243 PMCID: PMC8383909 DOI: 10.1093/molbev/msab140] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
De novo mutations are central for evolution, since they provide the raw material for natural selection by regenerating genetic variation. However, studying de novo mutations is challenging and is generally restricted to model species, so we have a limited understanding of the evolution of the mutation rate and spectrum between closely related species. Here, we present a mutation accumulation (MA) experiment to study de novo mutation in the unicellular green alga Chlamydomonas incerta and perform comparative analyses with its closest known relative, Chlamydomonas reinhardtii. Using whole-genome sequencing data, we estimate that the median single nucleotide mutation (SNM) rate in C. incerta is μ = 7.6 × 10-10, and is highly variable between MA lines, ranging from μ = 0.35 × 10-10 to μ = 131.7 × 10-10. The SNM rate is strongly positively correlated with the mutation rate for insertions and deletions between lines (r > 0.97). We infer that the genomic factors associated with variation in the mutation rate are similar to those in C. reinhardtii, allowing for cross-prediction between species. Among these genomic factors, sequence context and complexity are more important than GC content. With the exception of a remarkably high C→T bias, the SNM spectrum differs markedly between the two Chlamydomonas species. Our results suggest that similar genomic and biological characteristics may result in a similar mutation rate in the two species, whereas the SNM spectrum has more freedom to diverge.
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Affiliation(s)
- Eugenio López-Cortegano
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jobran Chebib
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Toby Samuels
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew D Morgan
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Katharina B Böndel
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, Stuttgart, Germany
| | - Rob W Ness
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Nick Colegrave
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter D Keightley
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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37
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Rajaei M, Saxena AS, Johnson LM, Snyder MC, Crombie TA, Tanny RE, Andersen EC, Joyner-Matos J, Baer CF. Mutability of mononucleotide repeats, not oxidative stress, explains the discrepancy between laboratory-accumulated mutations and the natural allele-frequency spectrum in C. elegans. Genome Res 2021; 31:1602-1613. [PMID: 34404692 PMCID: PMC8415377 DOI: 10.1101/gr.275372.121] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 07/12/2021] [Indexed: 11/24/2022]
Abstract
Important clues about natural selection can be gleaned from discrepancies between the properties of segregating genetic variants and of mutations accumulated experimentally under minimal selection, provided the mutational process is the same in the laboratory as in nature. The base-substitution spectrum differs between C. elegans laboratory mutation accumulation (MA) experiments and the standing site-frequency spectrum, which has been argued to be in part owing to increased oxidative stress in the laboratory environment. Using genome sequence data from C. elegans MA lines carrying a mutation (mev-1) that increases the cellular titer of reactive oxygen species (ROS), leading to increased oxidative stress, we find the base-substitution spectrum is similar between mev-1, its wild-type progenitor (N2), and another set of MA lines derived from a different wild strain (PB306). Conversely, the rate of short insertions is greater in mev-1, consistent with studies in other organisms in which environmental stress increased the rate of insertion–deletion mutations. Further, the mutational properties of mononucleotide repeats in all strains are different from those of nonmononucleotide sequence, both for indels and base-substitutions, and whereas the nonmononucleotide spectra are fairly similar between MA lines and wild isolates, the mononucleotide spectra are very different, with a greater frequency of A:T → T:A transversions and an increased proportion of ±1-bp indels. The discrepancy in mutational spectra between laboratory MA experiments and natural variation is likely owing to a consistent (but unknown) effect of the laboratory environment that manifests itself via different modes of mutability and/or repair at mononucleotide loci.
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Affiliation(s)
- Moein Rajaei
- Department of Biology, University of Florida, Gainesville, Florida 32611, USA
| | | | - Lindsay M Johnson
- Department of Biology, University of Florida, Gainesville, Florida 32611, USA
| | - Michael C Snyder
- Department of Biology, University of Florida, Gainesville, Florida 32611, USA
| | - Timothy A Crombie
- Department of Biology, University of Florida, Gainesville, Florida 32611, USA.,Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA
| | - Robyn E Tanny
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA
| | - Erik C Andersen
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA
| | - Joanna Joyner-Matos
- Department of Biology, Eastern Washington University, Cheney, Washington 99004, USA
| | - Charles F Baer
- Department of Biology, University of Florida, Gainesville, Florida 32611, USA.,University of Florida Genetics Institute, Gainesville, Florida 32608, USA
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38
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Krasovec M. The spontaneous mutation rate of Drosophila pseudoobscura. G3 GENES|GENOMES|GENETICS 2021; 11:6265464. [PMID: 33950174 PMCID: PMC8495931 DOI: 10.1093/g3journal/jkab151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/26/2021] [Indexed: 02/05/2023]
Abstract
Abstract
The spontaneous mutation rate is a very variable trait that is subject to drift, selection and is sometimes highly plastic. Consequently, its variation between close species, or even between populations from the same species, can be very large. Here, I estimated the spontaneous mutation rate of Drosophila pseudoobscura and Drosophila persimilis crosses to explore the mutation rate variation within the Drosophila genus. All mutation rate estimations in Drosophila varied fourfold, probably explained by the sensitivity of the mutation rate to environmental and experimental conditions. Moreover, I found a very high mutation rate in the hybrid cross between D. pseudoobscura and D. persimilis, in agreement with known elevated mutation rate in hybrids. This mutation rate increase can be explained by heterozygosity and fitness decrease effects in hybrids.
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Affiliation(s)
- Marc Krasovec
- CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls-sur-Mer 66650, France
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39
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Krasovec M, Rickaby REM, Filatov DA. Evolution of Mutation Rate in Astronomically Large Phytoplankton Populations. Genome Biol Evol 2021; 12:1051-1059. [PMID: 32645145 PMCID: PMC7486954 DOI: 10.1093/gbe/evaa131] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2020] [Indexed: 02/06/2023] Open
Abstract
Genetic diversity is expected to be proportional to population size, yet, there is a well-known, but unexplained lack of genetic diversity in large populations-the "Lewontin's paradox." Larger populations are expected to evolve lower mutation rates, which may help to explain this paradox. Here, we test this conjecture by measuring the spontaneous mutation rate in a ubiquitous unicellular marine phytoplankton species Emiliania huxleyi (Haptophyta) that has modest genetic diversity despite an astronomically large population size. Genome sequencing of E. huxleyi mutation accumulation lines revealed 455 mutations, with an unusual GC-biased mutation spectrum. This yielded an estimate of the per site mutation rate µ = 5.55×10-10 (CI 95%: 5.05×10-10 - 6.09×10-10), which corresponds to an effective population size Ne ∼ 2.7×106. Such a modest Ne is surprising for a ubiquitous and abundant species that accounts for up to 10% of global primary productivity in the oceans. Our results indicate that even exceptionally large populations do not evolve mutation rates lower than ∼10-10 per nucleotide per cell division. Consequently, the extreme disparity between modest genetic diversity and astronomically large population size in the plankton species cannot be explained by an unusually low mutation rate.
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Affiliation(s)
- Marc Krasovec
- Department of Plant Sciences, University of Oxford, United Kingdom
| | | | - Dmitry A Filatov
- Department of Plant Sciences, University of Oxford, United Kingdom
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40
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The rate and molecular spectrum of mutation are selectively maintained in yeast. Nat Commun 2021; 12:4044. [PMID: 34193872 PMCID: PMC8245649 DOI: 10.1038/s41467-021-24364-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/10/2021] [Indexed: 12/25/2022] Open
Abstract
What determines the rate (μ) and molecular spectrum of mutation is a fundamental question. The prevailing hypothesis asserts that natural selection against deleterious mutations has pushed μ to the minimum achievable in the presence of genetic drift, or the drift barrier. Here we show that, contrasting this hypothesis, μ substantially exceeds the drift barrier in diverse organisms. Random mutation accumulation (MA) in yeast frequently reduces μ, and deleting the newly discovered mutator gene PSP2 nearly halves μ. These results, along with a comparison between the MA and natural yeast strains, demonstrate that μ is maintained above the drift barrier by stabilizing selection. Similar comparisons show that the mutation spectrum such as the universal AT mutational bias is not intrinsic but has been selectively preserved. These findings blur the separation of mutation from selection as distinct evolutionary forces but open the door to alleviating mutagenesis in various organisms by genome editing. How natural selection shapes the rate and molecular spectrum of mutations is debated. Yeast mutation accumulation experiments identify a gene promoting mutagenesis and show stabilizing selection maintaining the mutation rate above the drift barrier. Selection also preserves the mutation spectrum.
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41
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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.
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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
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42
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Zou Z, Zhang J. Are Nonsynonymous Transversions Generally More Deleterious than Nonsynonymous Transitions? Mol Biol Evol 2021; 38:181-191. [PMID: 32805043 PMCID: PMC7783172 DOI: 10.1093/molbev/msaa200] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
It has been suggested that, due to the structure of the genetic code, nonsynonymous transitions are less likely than transversions to cause radical changes in amino acid physicochemical properties so are on average less deleterious. This view was supported by some but not all mutagenesis experiments. Because laboratory measures of fitness effects have limited sensitivities and relative frequencies of different mutations in mutagenesis studies may not match those in nature, we here revisit this issue using comparative genomics. We extend the standard codon model of sequence evolution by adding the parameter η that quantifies the ratio of the fixation probability of transitional nonsynonymous mutations to that of transversional nonsynonymous mutations. We then estimate η from the concatenated alignment of all protein-coding DNA sequences of two closely related genomes. Surprisingly, η ranges from 0.13 to 2.0 across 90 species pairs sampled from the tree of life, with 51 incidences of η < 1 and 30 incidences of η >1 that are statistically significant. Hence, whether nonsynonymous transversions are overall more deleterious than nonsynonymous transitions is species-dependent. Because the corresponding groups of amino acid replacements differ between nonsynonymous transitions and transversions, η is influenced by the relative exchangeabilities of amino acid pairs. Indeed, an extensive search reveals that the large variation in η is primarily explainable by the recently reported among-species disparity in amino acid exchangeabilities. These findings demonstrate that genome-wide nucleotide substitution patterns in coding sequences have species-specific features and are more variable among evolutionary lineages than are currently thought.
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Affiliation(s)
- Zhengting Zou
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
- Corresponding author: E-mail: .Associate editor: Jeffrey Townsend
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43
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Auboeuf D. The Physics-Biology continuum challenges darwinism: Evolution is directed by the homeostasis-dependent bidirectional relation between genome and phenotype. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 167:121-139. [PMID: 34097984 DOI: 10.1016/j.pbiomolbio.2021.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/19/2021] [Accepted: 05/31/2021] [Indexed: 10/21/2022]
Abstract
The physics-biology continuum relies on the fact that life emerged from prebiotic molecules. Here, I argue that life emerged from the coupling between nucleic acid and protein synthesis during which proteins (or proto-phenotypes) maintained the physicochemical parameter equilibria (or proto-homeostasis) in the proximity of their encoding nucleic acids (or proto-genomes). This protected the proto-genome physicochemical integrity (i.e., atomic composition) from environmental physicochemical constraints, and therefore increased the probability of reproducing the proto-genome without variation. From there, genomes evolved depending on the biological activities they generated in response to environmental fluctuations. Thus, a genome maintaining homeostasis (i.e., internal physicochemical parameter equilibria), despite and in response to environmental fluctuations, maintains its physicochemical integrity and has therefore a higher probability to be reproduced without variation. Consequently, descendants have a higher probability to share the same phenotype than their parents. Otherwise, the genome is modified during replication as a consequence of the imbalance of the internal physicochemical parameters it generates, until new mutation-deriving biological activities maintain homeostasis in offspring. In summary, evolution depends on feedforward and feedback loops between genome and phenotype, as the internal physicochemical conditions that a genome generates ─ through its derived phenotype in response to environmental fluctuations ─ in turn either guarantee its stability or direct its variation. Evolution may not be explained by the Darwinism-derived, unidirectional principle (random mutations-phenotypes-natural selection) but rather by the bidirectional relationship between genome and phenotype, in which the phenotype in interaction with the environment directs the evolution of the genome it derives from.
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Affiliation(s)
- Didier Auboeuf
- ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée D'Italie, Site Jacques Monod, F-69007, Lyon, France.
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44
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Nguyen DT, Wu B, Long H, Zhang N, Patterson C, Simpson S, Morris K, Thomas WK, Lynch M, Hao W. Variable Spontaneous Mutation and Loss of Heterozygosity among Heterozygous Genomes in Yeast. Mol Biol Evol 2021; 37:3118-3130. [PMID: 33219379 DOI: 10.1093/molbev/msaa150] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mutation and recombination are the primary sources of genetic variation. To better understand the evolution of genetic variation, it is crucial to comprehensively investigate the processes involving mutation accumulation and recombination. In this study, we performed mutation accumulation experiments on four heterozygous diploid yeast species in the Saccharomycodaceae family to determine spontaneous mutation rates, mutation spectra, and losses of heterozygosity (LOH). We observed substantial variation in mutation rates and mutation spectra. We also observed high LOH rates (1.65-11.07×10-6 events per heterozygous site per cell division). Biases in spontaneous mutation and LOH together with selection ultimately shape the variable genome-wide nucleotide landscape in yeast species.
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Affiliation(s)
- Duong T Nguyen
- Department of Biological Sciences, Wayne State University, Detroit, MI
| | - Baojun Wu
- Department of Biological Sciences, Wayne State University, Detroit, MI
| | - Hongan Long
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
| | - Nan Zhang
- Department of Biological Sciences, Wayne State University, Detroit, MI
| | | | | | | | | | - Michael Lynch
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, AZ
| | - Weilong Hao
- Department of Biological Sciences, Wayne State University, Detroit, MI
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45
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Chen P, Zhang J. Asexual Experimental Evolution of Yeast Does Not Curtail Transposable Elements. Mol Biol Evol 2021; 38:2831-2842. [PMID: 33720342 PMCID: PMC8233515 DOI: 10.1093/molbev/msab073] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Compared with asexual reproduction, sex facilitates the transmission of transposable elements (TEs) from one genome to another, but boosts the efficacy of selection against deleterious TEs. Thus, theoretically, it is unclear whether sex has a positive net effect on TE’s proliferation. An empirical study concluded that sex is at the root of TE’s evolutionary success because the yeast TE load was found to decrease rapidly in approximately 1,000 generations of asexual but not sexual experimental evolution. However, this finding contradicts the maintenance of TEs in natural yeast populations where sexual reproduction occurs extremely infrequently. Here, we show that the purported TE load reduction during asexual experimental evolution is likely an artifact of low genomic sequencing coverages. We observe stable TE loads in both sexual and asexual experimental evolution from multiple yeast data sets with sufficient coverages. To understand the evolutionary dynamics of yeast TEs, we turn to asexual mutation accumulation lines that have been under virtually no selection. We find that both TE transposition and excision rates per generation, but not their difference, tend to be higher in environments where yeast grows more slowly. However, the transposition rate is not significantly higher than the excision rate and the variance of the TE number among natural strains is close to its neutral expectation, suggesting that selection against TEs is at best weak in yeast. We conclude that the yeast TE load is maintained largely by a transposition–excision balance and that the influence of sex remains unclear.
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Affiliation(s)
- Piaopiao Chen
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
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46
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Genome-scale reconstructions to assess metabolic phylogeny and organism clustering. PLoS One 2020; 15:e0240953. [PMID: 33373364 PMCID: PMC7771690 DOI: 10.1371/journal.pone.0240953] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 11/28/2020] [Indexed: 12/28/2022] Open
Abstract
Approaches for systematizing information of relatedness between organisms is important in biology. Phylogenetic analyses based on sets of highly conserved genes are currently the basis for the Tree of Life. Genome-scale metabolic reconstructions contain high-quality information regarding the metabolic capability of an organism and are typically restricted to metabolically active enzyme-encoding genes. While there are many tools available to generate draft reconstructions, expert-level knowledge is still required to generate and manually curate high-quality genome-scale metabolic models and to fill gaps in their reaction networks. Here, we use the tool AutoKEGGRec to construct 975 genome-scale metabolic draft reconstructions encoded in the KEGG database without further curation. The organisms are selected across all three domains, and their metabolic networks serve as basis for generating phylogenetic trees. We find that using all reactions encoded, these metabolism-based comparisons give rise to a phylogenetic tree with close similarity to the Tree of Life. While this tree is quite robust to reasonable levels of noise in the metabolic reaction content of an organism, we find a significant heterogeneity in how much noise an organism may tolerate before it is incorrectly placed in the tree. Furthermore, by using the protein sequences for particular metabolic functions and pathway sets, such as central carbon-, nitrogen-, and sulfur-metabolism, as basis for the organism comparisons, we generate highly specific phylogenetic trees. We believe the generation of phylogenetic trees based on metabolic reaction content, in particular when focused on specific functions and pathways, could aid the identification of functionally important metabolic enzymes and be of value for genome-scale metabolic modellers and enzyme-engineers.
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47
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Belfield EJ, Brown C, Ding ZJ, Chapman L, Luo M, Hinde E, van Es SW, Johnson S, Ning Y, Zheng SJ, Mithani A, Harberd NP. Thermal stress accelerates Arabidopsis thaliana mutation rate. Genome Res 2020; 31:40-50. [PMID: 33334733 PMCID: PMC7849391 DOI: 10.1101/gr.259853.119] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 10/28/2020] [Indexed: 01/07/2023]
Abstract
Mutations are the source of both genetic diversity and mutational load. However, the effects of increasing environmental temperature on plant mutation rates and relative impact on specific mutational classes (e.g., insertion/deletion [indel] vs. single nucleotide variant [SNV]) are unknown. This topic is important because of the poorly defined effects of anthropogenic global temperature rise on biological systems. Here, we show the impact of temperature increase on Arabidopsis thaliana mutation, studying whole genome profiles of mutation accumulation (MA) lineages grown for 11 successive generations at 29°C. Whereas growth of A. thaliana at standard temperature (ST; 23°C) is associated with a mutation rate of 7 × 10−9 base substitutions per site per generation, growth at stressful high temperature (HT; 29°C) is highly mutagenic, increasing the mutation rate to 12 × 10−9. SNV frequency is approximately two- to threefold higher at HT than at ST, and HT-growth causes an ∼19- to 23-fold increase in indel frequency, resulting in a disproportionate increase in indels (vs. SNVs). Most HT-induced indels are 1–2 bp in size and particularly affect homopolymeric or dinucleotide A or T stretch regions of the genome. HT-induced indels occur disproportionately in nucleosome-free regions, suggesting that much HT-induced mutational damage occurs during cell-cycle phases when genomic DNA is packaged into nucleosomes. We conclude that stressful experimental temperature increases accelerate plant mutation rates and particularly accelerate the rate of indel mutation. Increasing environmental temperatures are thus likely to have significant mutagenic consequences for plants growing in the wild and may, in particular, add detrimentally to mutational load.
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Affiliation(s)
- Eric J Belfield
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Carly Brown
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Zhong Jie Ding
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Lottie Chapman
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Mengqian Luo
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Eleanor Hinde
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Sam W van Es
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, SE-901 87 Umeå, Sweden
| | - Sophie Johnson
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Youzheng Ning
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Shao Jian Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Aziz Mithani
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences (LUMS), DHA, Lahore 54792, Pakistan
| | - Nicholas P Harberd
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
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48
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Li J, Rinnerthaler M, Hartl J, Weber M, Karl T, Breitenbach-Koller H, Mülleder M, Vowinckel J, Marx H, Sauer M, Mattanovich D, Ata Ö, De S, Greslehner GP, Geltinger F, Burhans B, Grant C, Doronina V, Ralser M, Streubel MK, Grabner C, Jarolim S, Moßhammer C, Gourlay CW, Hasek J, Cullen PJ, Liti G, Ralser M, Breitenbach M. Slow Growth and Increased Spontaneous Mutation Frequency in Respiratory Deficient afo1- Yeast Suppressed by a Dominant Mutation in ATP3. G3 (BETHESDA, MD.) 2020; 10:4637-4648. [PMID: 33093184 PMCID: PMC7718765 DOI: 10.1534/g3.120.401537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 10/19/2020] [Indexed: 12/26/2022]
Abstract
A yeast deletion mutation in the nuclear-encoded gene, AFO1, which codes for a mitochondrial ribosomal protein, led to slow growth on glucose, the inability to grow on glycerol or ethanol, and loss of mitochondrial DNA and respiration. We noticed that afo1- yeast readily obtains secondary mutations that suppress aspects of this phenotype, including its growth defect. We characterized and identified a dominant missense suppressor mutation in the ATP3 gene. Comparing isogenic slowly growing rho-zero and rapidly growing suppressed afo1- strains under carefully controlled fermentation conditions showed that energy charge was not significantly different between strains and was not causal for the observed growth properties. Surprisingly, in a wild-type background, the dominant suppressor allele of ATP3 still allowed respiratory growth but increased the petite frequency. Similarly, a slow-growing respiratory deficient afo1- strain displayed an about twofold increase in spontaneous frequency of point mutations (comparable to the rho-zero strain) while the suppressed strain showed mutation frequency comparable to the respiratory-competent WT strain. We conclude, that phenotypes that result from afo1- are mostly explained by rapidly emerging mutations that compensate for the slow growth that typically follows respiratory deficiency.
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Affiliation(s)
- Jing Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
- Universite Cote d'Azur, CNRS, Inserm, IRCAN, Nice, France
| | | | - Johannes Hartl
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
- Department of Biochemistry, Charité University Medicine, Berlin Germany
| | - Manuela Weber
- Department of Biosciences, University of Salzburg, Austria
| | - Thomas Karl
- Department of Biosciences, University of Salzburg, Austria
| | | | - Michael Mülleder
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
- Department of Biochemistry, Charité University Medicine, Berlin Germany
- The Molecular Biology of Metabolism Laboratory, The Francis Crick Institute, 1Midland Rd, London NW1 1AT, UK
| | - Jakob Vowinckel
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
- Biognosys AG, Wagistrasse 21, 8952 Schlieren, Switzerland
| | - Hans Marx
- Institute of Microbiology and Microbial Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Michael Sauer
- Institute of Microbiology and Microbial Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Diethard Mattanovich
- Institute of Microbiology and Microbial Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
- ACIB GmbH, Austrian Centre of Industrial Biotechnology, Muthgasse 11, A-1190 Vienna, Austria
| | - Özge Ata
- Institute of Microbiology and Microbial Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
- ACIB GmbH, Austrian Centre of Industrial Biotechnology, Muthgasse 11, A-1190 Vienna, Austria
| | - Sonakshi De
- Institute of Microbiology and Microbial Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
- ACIB GmbH, Austrian Centre of Industrial Biotechnology, Muthgasse 11, A-1190 Vienna, Austria
| | | | | | - Bill Burhans
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, New York
| | - Chris Grant
- Faculty of Biology, Medicine, and Health, University of Manchester, Manchester M13 9PT, UK
| | | | - Meryem Ralser
- The Molecular Biology of Metabolism Laboratory, The Francis Crick Institute, 1Midland Rd, London NW1 1AT, UK
| | | | | | | | | | - Campbell W Gourlay
- Department of Biosciences, University of Kent, Canterbury Kent CT2 7NJ, United Kingdom
| | - Jiri Hasek
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic
| | - Paul J Cullen
- Department of Biological Sciences, University at Buffalo, NY 14260
| | - Gianni Liti
- Institute for Research on Cancer and Ageing of Nice (IRCAN), CNRS, INSERM, Université Côte d'Azur, 06107 NICE, France
| | - Markus Ralser
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
- Department of Biochemistry, Charité University Medicine, Berlin Germany
- The Molecular Biology of Metabolism Laboratory, The Francis Crick Institute, 1Midland Rd, London NW1 1AT, UK
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Effect of Salt Stress on Mutation and Genetic Architecture for Fitness Components in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2020; 10:3831-3842. [PMID: 32847816 PMCID: PMC7534429 DOI: 10.1534/g3.120.401593] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mutations shape genetic architecture and thus influence the evolvability, adaptation and diversification of populations. Mutations may have different and even opposite effects on separate fitness components, and their rate of origin, distribution of effects and variance-covariance structure may depend on environmental quality. We performed an approximately 1,500-generation mutation-accumulation (MA) study in diploids of the yeast Saccharomyces cerevisiae in stressful (high-salt) and normal environments (50 lines each) to investigate the rate of input of mutational variation (Vm) as well as the mutation rate and distribution of effects on diploid and haploid fitness components, assayed in the normal environment. All four fitness components in both MA treatments exhibited statistically significant mutational variance and mutational heritability. Compared to normal-MA, salt stress increased the mutational variance in growth rate by more than sevenfold in haploids derived from the MA lines. This increase was not detected in diploid growth rate, suggesting masking of mutations in the heterozygous state. The genetic architecture arising from mutation (M-matrix) differed between normal and salt conditions. Salt stress also increased environmental variance in three fitness components, consistent with a reduction in canalization. Maximum-likelihood analysis indicated that stress increased the genomic mutation rate by approximately twofold for maximal growth rate and sporulation rate in diploids and for viability in haploids, and by tenfold for maximal growth rate in haploids, but large confidence intervals precluded distinguishing these values between MA environments. We discuss correlations between fitness components in diploids and haploids and compare the correlations between the two MA environmental treatments.
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50
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Loss of Heterozygosity and Base Mutation Rates Vary Among Saccharomyces cerevisiae Hybrid Strains. G3-GENES GENOMES GENETICS 2020; 10:3309-3319. [PMID: 32727920 PMCID: PMC7466981 DOI: 10.1534/g3.120.401551] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A growing body of evidence suggests that mutation rates exhibit intra-species specific variation. We estimated genome-wide loss of heterozygosity (LOH), gross chromosomal changes, and single nucleotide mutation rates to determine intra-species specific differences in hybrid and homozygous strains of Saccharomyces cerevisiae. The mutation accumulation lines of the S. cerevisiae hybrid backgrounds - S288c/YJM789 (S/Y) and S288c/RM11-1a (S/R) were analyzed along with the homozygous diploids RM11, S288c, and YJM145. LOH was extensive in both S/Y and S/R hybrid backgrounds. The S/Y background also showed longer LOH tracts, gross chromosomal changes, and aneuploidy. Short copy number aberrations were observed in the S/R background. LOH data from the S/Y and S/R hybrids were used to construct a LOH map for S288c to identify hotspots. Further, we observe up to a sixfold difference in single nucleotide mutation rates among the S. cerevisiae S/Y and S/R genetic backgrounds. Our results demonstrate LOH is common during mitotic divisions in S. cerevisiae hybrids and also highlight genome-wide differences in LOH patterns and rates of single nucleotide mutations between commonly used S. cerevisiae hybrid genetic backgrounds.
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