scholarly journals Known mutator alleles do not markedly increase mutation rate in clinical Saccharomyces cerevisiae strains

2017 ◽  
Vol 284 (1852) ◽  
pp. 20162672 ◽  
Author(s):  
Daniel A. Skelly ◽  
Paul M. Magwene ◽  
Brianna Meeks ◽  
Helen A. Murphy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mutation Rate ◽  
Evolutionary Theory ◽  
Phylogenetic Analyses ◽  
Genetic Modifiers ◽  
Beneficial Mutations ◽  
Mutator Allele ◽  
Genomic Mutation ◽  
Asexual Populations ◽  
The Relationship

Natural selection has the potential to act on all phenotypes, including genomic mutation rate. Classic evolutionary theory predicts that in asexual populations, mutator alleles, which cause high mutation rates, can fix due to linkage with beneficial mutations. This phenomenon has been demonstrated experimentally and may explain the frequency of mutators found in bacterial pathogens. By contrast, in sexual populations, recombination decouples mutator alleles from beneficial mutations, preventing mutator fixation. In the facultatively sexual yeast Saccharomyces cerevisiae , segregating alleles of MLH1 and PMS1 have been shown to be incompatible, causing a high mutation rate when combined. These alleles had never been found together naturally, but were recently discovered in a cluster of clinical isolates. Here we report that the incompatible mutator allele combination only marginally elevates mutation rate in these clinical strains. Genomic and phylogenetic analyses provide no evidence of a historically elevated mutation rate. We conclude that the effect of the mutator alleles is dampened by background genetic modifiers. Thus, the relationship between mutation rate and microbial pathogenicity may be more complex than once thought. Our findings provide rare observational evidence that supports evolutionary theory suggesting that sexual organisms are unlikely to harbour alleles that increase their genomic mutation rate.

scholarly journals The effect of known mutator alleles in a cluster of clinicalSaccharomyces cerevisiaestrains

2016 ◽  
Author(s):  
Daniel A. Skelly ◽  
Paul M. Magwene ◽  
Brianna Meeks ◽  
Helen A. Murphy
Keyword(s):  
Mutation Rate ◽  
Evolutionary Theory ◽  
Phylogenetic Analyses ◽  
Mutation Rates ◽  
Genetic Modifiers ◽  
Beneficial Mutations ◽  
Mutator Allele ◽  
Genomic Mutation ◽  
Asexual Populations ◽  
The Relationship

AbstractNatural selection has the potential to act on all phenotypes, including genomic mutation rate. Classic evolutionary theory predicts that in asexual populations, mutator alleles, which cause high mutation rates, can fix due to linkage with beneficial mutations. This phenomenon has been demonstrated experimentally and may explain the frequency of mutators found in bacterial pathogens. In contrast, in sexual populations, recombination decouples mutator alleles from beneficial mutations, preventing mutator fixation. In the facultatively sexual yeastSaccharomyces cerevisiae, segregating alleles ofMLH1andPMS1have been shown to be incompatible, causing a high mutation rate when combined. These alleles had never been found together naturally, but were recently discovered in a cluster of clinical isolates. Here we report that the incompatible mutator allele combination only marginally elevates mutation rate in these clinical strains. Genomic and phylogenetic analyses provide no evidence of a historically elevated mutation rate. We conclude that the effect of the mutator alleles is dampened by background genetic modifiers. Thus, the relationship between mutation rate and microbial pathogenicity may be more complex than once thought. Our findings provide rare observational evidence that supports evolutionary theory suggesting that sexual organisms are unlikely to harbor alleles that increase their genomic mutation rate.

scholarly journals Competition between high- and higher-mutating strains of Escherichia coli

2011 ◽  
Vol 7 (3) ◽  
pp. 422-424 ◽  
Author(s):  
Christopher F. Gentile ◽  
Szi-Chieh Yu ◽  
Sebastian Akle Serrano ◽  
Philip J. Gerrish ◽  
Paul D. Sniegowski
Keyword(s):  
Escherichia Coli ◽  
Mutation Rate ◽  
Experimental Studies ◽  
Recent Theory ◽  
Wild Type ◽  
Asexual Population ◽  
Beneficial Mutations ◽  
Experimental Support ◽  
Mutator Allele ◽  
Asexual Populations

Experimental studies have shown that a mutator allele can readily hitchhike to fixation with beneficial mutations in an asexual population having a low, wild-type mutation rate. Here, we show that a genotype bearing two mutator alleles can supplant a population already fixed for one mutator allele. Our results provide experimental support for recent theory predicting that mutator alleles will tend to accumulate in asexual populations by hitchhiking with beneficial mutations, causing an ever-higher genomic mutation rate.

scholarly journals Spontaneous mutations in diploid Saccharomyces cerevisiae: another thousand cell generations

2008 ◽  
Vol 90 (3) ◽  
pp. 229-241 ◽  
Author(s):  
DAVID W. HALL ◽  
ROD MAHMOUDIZAD ◽  
ANDREW W. HURD ◽  
SARAH B. JOSEPH
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mutation Rate ◽  
Sampling Error ◽  
Cell Generation ◽  
Haploid Genome ◽  
Spontaneous Mutations ◽  
Beneficial Mutations ◽  
Absolute Value ◽  
Genome Wide ◽  
The Impact

SummaryPreviously we performed a 1012-generation mutation accumulation (MA) study in yeast and found that a surprisingly large proportion of fitness-altering mutations were beneficial. To verify this result and assess the impact of sampling error in our previous study, we have continued the MA experiment for an additional 1050 cell generations and re-estimated mutation parameters. After correcting for biases due to selection, we estimate that 13% of the mutations accumulated during this study are beneficial. We conclude that the high proportions of beneficial mutations observed in this and our previous study cannot be explained by sampling error. We also estimate the genome-wide mutation rate to be 13·7×10−5 mutations per haploid genome per cell generation and the absolute value of the average heterozygous effect of a mutation to be 7·3%.

scholarly journals On the Rate and Linearity of Viability Declines in Drosophila Mutation-Accumulation Experiments: Genomic Mutation Rates and Synergistic Epistasis Revisited

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 797-806 ◽  
Author(s):  
James D Fry
Keyword(s):  
Mutation Rate ◽  
Average Rate ◽  
Natural Populations ◽  
Mutation Accumulation ◽  
High Rate ◽  
Deleterious Mutations ◽  
Order Of Magnitude ◽  
Contamination Event ◽  
Genomic Mutation ◽  
The 1960S

Abstract High rates of deleterious mutations could severely reduce the fitness of populations, even endangering their persistence; these effects would be mitigated if mutations synergize each others’ effects. An experiment by Mukai in the 1960s gave evidence that in Drosophila melanogaster, viability-depressing mutations occur at the surprisingly high rate of around one per zygote and that the mutations interact synergistically. A later experiment by Ohnishi seemed to support the high mutation rate, but gave no evidence for synergistic epistasis. Both of these studies, however, were flawed by the lack of suitable controls for assessing viability declines of the mutation-accumulation (MA) lines. By comparing homozygous viability of the MA lines to simultaneously estimated heterozygous viability and using estimates of the dominance of mutations in the experiments, I estimate the viability declines relative to an appropriate control. This approach yields two unexpected conclusions. First, in Ohnishi’s experiment as well as in Mukai’s, MA lines showed faster-than-linear declines in viability, indicative of synergistic epistasis. Second, while Mukai’s estimate of the genomic mutation rate is supported, that from Ohnishi’s experiment is an order of magnitude lower. The different results of the experiments most likely resulted from differences in the starting genotypes; even within Mukai’s experiment, a subset of MA lines, which I argue probably resulted from a contamination event, showed much slower viability declines than did the majority of lines. Because different genotypes may show very different mutational behavior, only studies using many founding genotypes can determine the average rate and distribution of effects of mutations relevant to natural populations.

scholarly journals A yeast metabolome-based model for an ecotoxicological approach in the management of lignocellulosic ethanol stillage

2019 ◽  
Vol 6 (1) ◽  
pp. 180718 ◽  
Author(s):  
Luca Roscini ◽  
Lorenzo Favaro ◽  
Laura Corte ◽  
Lorenzo Cagnin ◽  
Claudia Colabella ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Saccharomyces Cerevisiae ◽  
Predictive Model ◽  
Lignocellulosic Ethanol ◽  
Bioethanol Production ◽  
Inhibitor Concentration ◽  
Promising Tool ◽  
Different Types ◽  
The Relationship ◽  
Ecotoxicological Bioassay

Lignocellulosic bioethanol production results in huge amounts of stillage, a potentially polluting by-product. Stillage, rich in heavy metals and, mainly, inhibitors, requires specific toxicity studies to be adequately managed. To this purpose, we applied an FTIR ecotoxicological bioassay to evaluate the toxicity of lignocellulosic stillage. Two weak acids and furans, most frequently found in lignocellulosic stillage, have been tested in different mixtures against three Saccharomyces cerevisiae strains. The metabolomic reaction of the test microbes and the mortality induced at various levels of inhibitor concentration showed that the strains are representative of three different types of response. Furthermore, the relationship between concentrations and FTIR synthetic stress indexes has been studied, with the aim of defining a model able to predict the concentrations of inhibitors in stillage, resulting in an optimized predictive model for all the strains. This approach represents a promising tool to support the ecotoxicological management of lignocellulosic stillage.

scholarly journals THE RELATIONSHIP BETWEEN RADIATION EXPOSURE AND MUTATION RATE AT THE DUMPY LOCUS IN DROSOPHILA

1974 ◽  
Vol 49 (6) ◽  
pp. 373-378 ◽  
Author(s):  
EIICHI INAGAKI ◽  
TOMIO MIYAMOTO ◽  
TOKIO DOMOTO
Keyword(s):  
Radiation Exposure ◽  
Mutation Rate ◽  
The Relationship

An investigation into the relationship between anti-Helicobacter pylori and anti-Saccharomyces cerevisiae antibodies in patients with axial spondyloarthritis and Crohn disease

2014 ◽  
Vol 35 (2) ◽  
pp. 359-366 ◽  
Author(s):  
Igor Kunze Rodrigues ◽  
Michele Andrigueti ◽  
Ione Dilma de Oliveira Gil ◽  
Leonardo de Lucca Schiavon ◽  
Kenia Rodrigues de Andrade ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Helicobacter Pylori ◽  
Crohn Disease ◽  
Axial Spondyloarthritis ◽  
The Relationship

scholarly journals Complete Mitogenomic Structure and Phylogenetic Implications of the Genus Ostrinia (Lepidoptera: Crambidae)

Insects ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 232
Author(s):  
Nan Zhou ◽  
Yanling Dong ◽  
Pingping Qiao ◽  
Zhaofu Yang
Keyword(s):  
Control Region ◽  
Ostrinia Nubilalis ◽  
Phylogenetic Analyses ◽  
Structural Elements ◽  
Ostrinia Furnacalis ◽  
Protein Coding ◽  
Phylogenetic Implications ◽  
Ostrinia Scapulalis ◽  
The Relationship ◽  
Rna Genes

To understand mitogenome characteristics and reveal phylogenetic relationships of the genus Ostrinia, including several notorious pests of great importance for crops, we sequenced the complete mitogenomes of four species: Ostrinia furnacalis (Guenée, 1854), Ostrinia nubilalis (Hübner, 1796), Ostrinia scapulalis (Walker, 1859) and Ostrinia zealis (Guenée, 1854). Results indicate that the four mitogenomes—O. furnacalis, O. nubilalis, O. scapulalis, and O. zealis—are 15,245, 15,248, 15,311, and 15,208 bp in size, respectively. All four mitogenomes are comprised of 37 encoded genes and a control region. All 13 protein-coding genes (PCGs) initiate with ATN and terminate with TAN, with the exception of cox1 that starts with CGA, and cox1, cox2, and nad5 that terminate with an incomplete codon T. All transfer RNA genes (tRNAs) present the typical clover-leaf secondary structure except for the trnS1 (AGN) gene. There are some conserved structural elements in the control region. Our analyses indicate that nad6 and atp6 exhibit higher evolution rates compared to other PCGs. Phylogenetic analyses based on mitogenomes using both maximum likelihood (ML) and Bayesian inference (BI) methods revealed the relationship (O. palustralis + (O. penitalis + (O. zealis + (O. furnacalis + (O. nubilalis + O. scapulalis))))) within Ostrinia.

scholarly journals GENETIC VARIABILITY MAINTAINED BY MUTATION AND OVERDOMINANT SELECTION IN FINITE POPULATIONS

Genetics ◽  
1981 ◽  
Vol 98 (2) ◽  
pp. 441-459 ◽  
Author(s):  
Takeo Maruyama ◽  
Masatoshi Nei
Keyword(s):  
Mutation Rate ◽  
Allozyme Polymorphism ◽  
Random Genetic Drift ◽  
Effective Population ◽  
Mathematical Properties ◽  
Overdominant Selection ◽  
Mean And Variance ◽  
The Mean ◽  
Neutral Mutations ◽  
The Relationship

ABSTRACT Mathematical properties of the overdominance model with mutation and random genetic drift are studied by using the method of stochastic differential equations (Itô and McKean 1974). It is shown that overdominant selection is very powerful in increasing the mean heterozygosity as compared with neutral mutations, and if 2Ns (N = effective population size; s = selective disadvantage for homozygotes) is larger than 10, a very low mutation rate is sufficient to explain the observed level of allozyme polymorphism. The distribution of heterozygosity for overdominant genes is considerably different from that of neutral mutations, and if the ratio of selection coefficient (s) to mutation rate (ν) is large and the mean heterozygosity (h) is lower than 0.2, single-locus heterozygosity is either approximately 0 or 0.5. If h increases further, however, heterozygosity shows a multiple-peak distribution. Reflecting this type of distribution, the relationship between the mean and variance of heterozygosity is considerably different from that for neutral genes. When s/v is large, the proportion of polymorphic loci increases approximately linearly with mean heterozygosity. The distribution of allele frequencies is also drastically different from that of neutral genes, and generally shows a peak at the intermediate gene frequency. Implications of these results on the maintenance of allozyme polymorphism are discussed.

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