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Tan CA, Westbrook MJ, Truty R, Kvitek DJ, Kennemer M, Winder TL, Shieh PB. Incorporating Spinal Muscular Atrophy Analysis by Next-Generation Sequencing into a Comprehensive Multigene Panel for Neuromuscular Disorders. Genet Test Mol Biomarkers 2020; 24:616-624. [PMID: 32721234 DOI: 10.1089/gtmb.2019.0282] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Background: Spinal muscular atrophy (SMA) is traditionally molecularly diagnosed by multiplex ligation-dependent probe amplification or quantitative polymerase chain reaction (qPCR). SMA analyses are not routinely incorporated into gene panel analyses for individuals with suspected SMA or broader neuromuscular indications. Aim: We sought to determine whether a next-generation sequencing (NGS) approach that integrates SMA analyses into a multigene neuromuscular disorders panel could detect undiagnosed SMA. Materials and Methods: Sequence and copy number variants of the SMN1/SMN2 genes were simultaneously analyzed in samples from 5304 unselected individuals referred for testing using an NGS-based 122-gene neuromuscular panel. This diagnostic approach was validated using DNA from 68 individuals who had been previously diagnosed with SMA via quantitative PCR for SMN1/SMN2. Results: Homozygous loss of SMN1 was detected in 47 unselected individuals. Heterozygous loss of SMN1 was detected in 118 individuals; 8 had an indeterminate variant in "SMN1 or SMN2" that supported an SMA diagnosis but required additional disambiguation. Of the remaining SMA carriers, 44 had pathogenic variants in other genes. Concordance rates between NGS and qPCR were 100% and 93% for SMN1 and SMN2 copy numbers, respectively. Where there was disagreement, phenotypes were more consistent with the SMN2 results from NGS. Conclusion: Integrating NGS-based SMA testing into a multigene neuromuscular panel allows a single assay to diagnose SMA while comprehensively assessing the spectrum of variants that can occur in individuals with broad differential diagnoses or nonspecific/overlapping neuromuscular features.
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Affiliation(s)
| | | | | | | | | | | | - Perry B Shieh
- Department of Neurology, University of California, Los Angeles, Los Angeles, California, USA
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2
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Lan N, Perlatti B, Kvitek DJ, Wiemann P, Harvey CJB, Frisvad J, An Z, Bills GF. Acrophiarin (antibiotic S31794/F-1) from Penicillium arenicola shares biosynthetic features with both Aspergillus- and Leotiomycete-type echinocandins. Environ Microbiol 2020; 22:2292-2311. [PMID: 32239586 DOI: 10.1111/1462-2920.15004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 03/28/2020] [Indexed: 11/30/2022]
Abstract
The antifungal echinocandin lipopeptide, acrophiarin, was circumscribed in a patent in 1979. We confirmed that the producing strain NRRL 8095 is Penicillium arenicola and other strains of P. arenicola produced acrophiarin and acrophiarin analogues. Genome sequencing of NRRL 8095 identified the acrophiarin gene cluster. Penicillium arenicola and echinocandin-producing Aspergillus species belong to the family Aspergillaceae of the Eurotiomycetes, but several features of acrophiarin and its gene cluster suggest a closer relationship with echinocandins from Leotiomycete fungi. These features include hydroxy-glutamine in the peptide core instead of a serine or threonine residue, the inclusion of a non-heme iron, α-ketoglutarate-dependent oxygenase for hydroxylation of the C3 of the glutamine, and a thioesterase. In addition, P. arenicola bears similarity to Leotiomycete echinocandin-producing species because it exhibits self-resistance to exogenous echinocandins. Phylogenetic analysis of the genes of the echinocandin biosynthetic family indicated that most of the predicted proteins of acrophiarin gene cluster exhibited higher similarity to the predicted proteins of the pneumocandin gene cluster of the Leotiomycete Glarea lozoyensis than to those of the echinocandin B gene cluster from A. pachycristatus. The fellutamide gene cluster and related gene clusters are recognized as relatives of the echinocandins. Inclusion of the acrophiarin gene cluster into a comprehensive phylogenetic analysis of echinocandin gene clusters indicated the divergent evolutionary lineages of echinocandin gene clusters are descendants from a common ancestral progenitor. The minimal 10-gene cluster may have undergone multiple gene acquisitions or losses and possibly horizontal gene transfer after the ancestral separation of the two lineages.
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Affiliation(s)
- Nan Lan
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, 77054, USA
| | - Bruno Perlatti
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, 77054, USA
| | | | | | | | - Jens Frisvad
- Center for Microbial Biotechnology, Department of Systems Biology, Technical University of Denmark, DK-2800, Lyngby, Denmark
| | - Zhiqiang An
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, 77054, USA
| | - Gerald F Bills
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, 77054, USA
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Chiotti KE, Kvitek DJ, Schmidt KH, Koniges G, Schwartz K, Donckels EA, Rosenzweig F, Sherlock G. The Valley-of-Death: reciprocal sign epistasis constrains adaptive trajectories in a constant, nutrient limiting environment. Genomics 2014; 104:431-7. [PMID: 25449178 DOI: 10.1016/j.ygeno.2014.10.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 10/29/2014] [Indexed: 12/25/2022]
Abstract
The fitness landscape is a powerful metaphor for describing the relationship between genotype and phenotype for a population under selection. However, empirical data as to the topography of fitness landscapes are limited, owing to difficulties in measuring fitness for large numbers of genotypes under any condition. We previously reported a case of reciprocal sign epistasis (RSE), where two mutations individually increased yeast fitness in a glucose-limited environment, but reduced fitness when combined, suggesting the existence of two peaks on the fitness landscape. We sought to determine whether a ridge connected these peaks so that populations founded by one mutant could reach the peak created by the other, avoiding the low-fitness "Valley-of-Death" between them. Sequencing clones after 250 generations of further evolution provided no evidence for such a ridge, but did reveal many presumptive beneficial mutations, adding to a growing body of evidence that clonal interference pervades evolving microbial populations.
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Affiliation(s)
- Kami E Chiotti
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Daniel J Kvitek
- Department of Genetics, Stanford University, Stanford, CA 94305-5120, USA
| | - Karen H Schmidt
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Gregory Koniges
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Katja Schwartz
- Department of Genetics, Stanford University, Stanford, CA 94305-5120, USA
| | | | - Frank Rosenzweig
- Division of Biological Sciences, University of Montana, Missoula, MT, USA.
| | - Gavin Sherlock
- Department of Genetics, Stanford University, Stanford, CA 94305-5120, USA.
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Spor A, Kvitek DJ, Nidelet T, Martin J, Legrand J, Dillmann C, Bourgais A, de Vienne D, Sherlock G, Sicard D. Phenotypic and genotypic convergences are influenced by historical contingency and environment in yeast. Evolution 2013; 68:772-790. [PMID: 24164389 DOI: 10.1111/evo.12302] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 10/14/2013] [Indexed: 12/26/2022]
Abstract
Different organisms have independently and recurrently evolved similar phenotypic traits at different points throughout history. This phenotypic convergence may be caused by genotypic convergence and in addition, constrained by historical contingency. To investigate how convergence may be driven by selection in a particular environment and constrained by history, we analyzed nine life-history traits and four metabolic traits during an experimental evolution of six yeast strains in four different environments. In each of the environments, the population converged toward a different multivariate phenotype. However, the evolution of most traits, including fitness components, was constrained by history. Phenotypic convergence was partly associated with the selection of mutations in genes involved in the same pathway. By further investigating the convergence in one gene, BMH1, mutated in 20% of the evolved populations, we show that both the history and the environment influenced the types of mutations (missense/nonsense), their location within the gene itself, as well as their effects on multiple traits. However, these effects could not be easily predicted from ancestors' phylogeny or past selection. Combined, our data highlight the role of pleiotropy and epistasis in shaping a rugged fitness landscape.
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Affiliation(s)
- Aymé Spor
- Univ Paris-Sud, UMR de Génétique Végétale, INRA / Univ Paris-Sud / CNRS, Ferme du Moulon, Gif-sur-Yvette, F-91190, France
| | - Daniel J Kvitek
- Department of Genetics, Stanford University, Stanford, CA 94305-5120, USA
| | | | - Juliette Martin
- Université Lyon 1; CNRS, UMR 5086; Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, 7 passage du, Vercors F-69367, France
| | - Judith Legrand
- Univ Paris-Sud, UMR de Génétique Végétale, INRA / Univ Paris-Sud / CNRS, Ferme du Moulon, Gif-sur-Yvette, F-91190, France
| | - Christine Dillmann
- Univ Paris-Sud, UMR de Génétique Végétale, INRA / Univ Paris-Sud / CNRS, Ferme du Moulon, Gif-sur-Yvette, F-91190, France
| | - Aurélie Bourgais
- CNRS, UMR de Génétique Végétale, INRA / Univ Paris-Sud / CNRS, Ferme du Moulon, Gif-sur-Yvette, F-91190, France
| | - Dominique de Vienne
- Univ Paris-Sud, UMR de Génétique Végétale, INRA / Univ Paris-Sud / CNRS, Ferme du Moulon, Gif-sur-Yvette, F-91190, France
| | - Gavin Sherlock
- Department of Genetics, Stanford University, Stanford, CA 94305-5120, USA
| | - Delphine Sicard
- Univ Paris-Sud, UMR de Génétique Végétale, INRA / Univ Paris-Sud / CNRS, Ferme du Moulon, Gif-sur-Yvette, F-91190, France
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5
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Kvitek DJ, Sherlock G. Whole genome, whole population sequencing reveals that loss of signaling networks is the major adaptive strategy in a constant environment. PLoS Genet 2013; 9:e1003972. [PMID: 24278038 PMCID: PMC3836717 DOI: 10.1371/journal.pgen.1003972] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 10/08/2013] [Indexed: 12/28/2022] Open
Abstract
Molecular signaling networks are ubiquitous across life and likely evolved to allow organisms to sense and respond to environmental change in dynamic environments. Few examples exist regarding the dispensability of signaling networks, and it remains unclear whether they are an essential feature of a highly adapted biological system. Here, we show that signaling network function carries a fitness cost in yeast evolving in a constant environment. We performed whole-genome, whole-population Illumina sequencing on replicate evolution experiments and find the major theme of adaptive evolution in a constant environment is the disruption of signaling networks responsible for regulating the response to environmental perturbations. Over half of all identified mutations occurred in three major signaling networks that regulate growth control: glucose signaling, Ras/cAMP/PKA and HOG. This results in a loss of environmental sensitivity that is reproducible across experiments. However, adaptive clones show reduced viability under starvation conditions, demonstrating an evolutionary tradeoff. These mutations are beneficial in an environment with a constant and predictable nutrient supply, likely because they result in constitutive growth, but reduce fitness in an environment where nutrient supply is not constant. Our results are a clear example of the myopic nature of evolution: a loss of environmental sensitivity in a constant environment is adaptive in the short term, but maladaptive should the environment change. When a population of organisms is faced with a selective pressure, such as a limiting nutrient, mutations that arise randomly may confer a fitness benefit on the individual carrying that mutation. If that individual reproduces before it is lost from the population, the frequency of that mutation may increase. Over time, many beneficial mutations will arise in a large population, but there are few high resolution experiments tracking the frequency of such mutations in an evolving population. We evolved populations of the baker's yeast in a constant environment in the presence of limiting amounts of sugar, and then used DNA sequencing to identify mutations that reached at least a 1% frequency in the population, and tracked them over time. We identified 120 mutations over three experiments, and determined that the genes and pathways that had gained beneficial mutations were largely reproducible across experiments, and that many of the mutations led to the loss of signaling pathways that usually sense a changing environment, allowing the cell to respond appropriately. When these mutant cells were faced with uncertain environments, the mutations proved to be deleterious. Environmental sensing must carry a fitness cost in a constant environment, but is essential in a changing one.
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Affiliation(s)
- Daniel J. Kvitek
- Department of Genetics, Stanford University, Stanford, California, United States of America
| | - Gavin Sherlock
- Department of Genetics, Stanford University, Stanford, California, United States of America
- * E-mail:
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6
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Dunn B, Richter C, Kvitek DJ, Pugh T, Sherlock G. Analysis of the Saccharomyces cerevisiae pan-genome reveals a pool of copy number variants distributed in diverse yeast strains from differing industrial environments. Genome Res 2012; 22:908-24. [PMID: 22369888 PMCID: PMC3337436 DOI: 10.1101/gr.130310.111] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Although the budding yeast Saccharomyces cerevisiae is arguably one of the most well-studied organisms on earth, the genome-wide variation within this species--i.e., its "pan-genome"--has been less explored. We created a multispecies microarray platform containing probes covering the genomes of several Saccharomyces species: S. cerevisiae, including regions not found in the standard laboratory S288c strain, as well as the mitochondrial and 2-μm circle genomes-plus S. paradoxus, S. mikatae, S. kudriavzevii, S. uvarum, S. kluyveri, and S. castellii. We performed array-Comparative Genomic Hybridization (aCGH) on 83 different S. cerevisiae strains collected across a wide range of habitats; of these, 69 were commercial wine strains, while the remaining 14 were from a diverse set of other industrial and natural environments. We observed interspecific hybridization events, introgression events, and pervasive copy number variation (CNV) in all but a few of the strains. These CNVs were distributed throughout the strains such that they did not produce any clear phylogeny, suggesting extensive mating in both industrial and wild strains. To validate our results and to determine whether apparently similar introgressions and CNVs were identical by descent or recurrent, we also performed whole-genome sequencing on nine of these strains. These data may help pinpoint genomic regions involved in adaptation to different industrial milieus, as well as shed light on the course of domestication of S. cerevisiae.
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Affiliation(s)
- Barbara Dunn
- Department of Genetics, Stanford University, Stanford, CA 94305-5120, USA
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Kvitek DJ, Sherlock G. Reciprocal sign epistasis between frequently experimentally evolved adaptive mutations causes a rugged fitness landscape. PLoS Genet 2011; 7:e1002056. [PMID: 21552329 PMCID: PMC3084205 DOI: 10.1371/journal.pgen.1002056] [Citation(s) in RCA: 215] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 03/07/2011] [Indexed: 12/31/2022] Open
Abstract
The fitness landscape captures the relationship between genotype and evolutionary fitness and is a pervasive metaphor used to describe the possible evolutionary trajectories of adaptation. However, little is known about the actual shape of fitness landscapes, including whether valleys of low fitness create local fitness optima, acting as barriers to adaptive change. Here we provide evidence of a rugged molecular fitness landscape arising during an evolution experiment in an asexual population of Saccharomyces cerevisiae. We identify the mutations that arose during the evolution using whole-genome sequencing and use competitive fitness assays to describe the mutations individually responsible for adaptation. In addition, we find that a fitness valley between two adaptive mutations in the genes MTH1 and HXT6/HXT7 is caused by reciprocal sign epistasis, where the fitness cost of the double mutant prohibits the two mutations from being selected in the same genetic background. The constraint enforced by reciprocal sign epistasis causes the mutations to remain mutually exclusive during the experiment, even though adaptive mutations in these two genes occur several times in independent lineages during the experiment. Our results show that epistasis plays a key role during adaptation and that inter-genic interactions can act as barriers between adaptive solutions. These results also provide a new interpretation on the classic Dobzhansky-Muller model of reproductive isolation and display some surprising parallels with mutations in genes often associated with tumors.
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Affiliation(s)
- Daniel J. Kvitek
- Department of Genetics, Stanford University, Stanford, California, United States of America
| | - Gavin Sherlock
- Department of Genetics, Stanford University, Stanford, California, United States of America
- * E-mail:
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8
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Kvitek DJ, Will JL, Gasch AP. Variations in stress sensitivity and genomic expression in diverse S. cerevisiae isolates. PLoS Genet 2008; 4:e1000223. [PMID: 18927628 PMCID: PMC2562515 DOI: 10.1371/journal.pgen.1000223] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 09/12/2008] [Indexed: 12/17/2022] Open
Abstract
Interactions between an organism and its environment can significantly influence
phenotypic evolution. A first step toward understanding this process is to
characterize phenotypic diversity within and between populations. We explored
the phenotypic variation in stress sensitivity and genomic expression in a large
panel of Saccharomyces strains collected from diverse
environments. We measured the sensitivity of 52 strains to 14 environmental
conditions, compared genomic expression in 18 strains, and identified gene
copy-number variations in six of these isolates. Our results demonstrate a large
degree of phenotypic variation in stress sensitivity and gene expression.
Analysis of these datasets reveals relationships between strains from similar
niches, suggests common and unique features of yeast habitats, and implicates
genes whose variable expression is linked to stress resistance. Using a simple
metric to suggest cases of selection, we found that strains collected from oak
exudates are phenotypically more similar than expected based on their genetic
diversity, while sake and vineyard isolates display more diverse phenotypes than
expected under a neutral model. We also show that the laboratory strain S288c is
phenotypically distinct from all of the other strains studied here, in terms of
stress sensitivity, gene expression, Ty copy number, mitochondrial content, and
gene-dosage control. These results highlight the value of understanding the
genetic basis of phenotypic variation and raise caution about using laboratory
strains for comparative genomics. Much attention has been given to the ways in which organisms evolve new
phenotypes and the influence of the environment on this process. A major focus
of study is defining the genetic basis for phenotypes important for organismal
fitness. As a first step toward this goal, we surveyed phenotypic variation in
diverse yeast strains collected from different environments by characterizing
variations in stress resistance and genomic expression. We uncovered many
phenotypic differences across yeast strains, both in stress tolerance and gene
expression. The similarities and differences of the strains analyzed uncovered
phenotypes shared by strains that live in similar environments, suggesting
common features of yeast niches as well as mechanisms that different strains use
to thrive in those conditions. We provide evidence that some characteristics of
strains isolated from oak tree soil have been selected for, perhaps because of
the shared selective pressures imposed by their environment. One theme emerging
from our studies is that the laboratory strain of yeast, long used as a model
for yeast physiology and basic biology, is aberrant compared to all other
strains. This result raises caution about making general conclusions about yeast
biology based on a single strain with a specific genetic makeup.
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Affiliation(s)
- Daniel J. Kvitek
- Laboratory of Genetics, University of Wisconsin–Madison,
Madison, Wisconsin, United States of America
| | - Jessica L. Will
- Laboratory of Genetics, University of Wisconsin–Madison,
Madison, Wisconsin, United States of America
| | - Audrey P. Gasch
- Laboratory of Genetics, University of Wisconsin–Madison,
Madison, Wisconsin, United States of America
- Genome Center of Wisconsin, University of Wisconsin–Madison,
Madison, Wisconsin, United States of America
- * E-mail:
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