scholarly journals Love the one you’re with: replicate viral adaptations converge on the same phenotypic change

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2227 ◽  
Author(s):  
Craig R. Miller ◽  
Anna C. Nagel ◽  
LuAnn Scott ◽  
Matt Settles ◽  
Paul Joyce ◽  
...  
Keyword(s):  
De Novo ◽  
Regulatory Elements ◽  
Host Cells ◽  
Phenotypic Change ◽  
De Novo Mutations ◽  
Promoter Mutation ◽  
Genetic Changes ◽  
Evolutionary Forces ◽  
Parallel Change ◽  
The One

Parallelism is important because it reveals how inherently stochastic adaptation is. Even as we come to better understand evolutionary forces, stochasticity limits how well we can predict evolutionary outcomes. Here we sought to quantify parallelism and some of its underlying causes by adapting a bacteriophage (ID11) with nine different first-step mutations, each with eight-fold replication, for 100 passages. This was followed by whole-genome sequencing five isolates from each endpoint. A large amount of variation arose—281 mutational events occurred representing 112 unique mutations. At least 41% of the mutations and 77% of the events were adaptive. Within wells, populations generally experienced complex interference dynamics. The genome locations and counts of mutations were highly uneven: mutations were concentrated in two regulatory elements and three genes and, while 103 of the 112 (92%) of the mutations were observed in ≤4 wells, a few mutations arose many times. 91% of the wells and 81% of the isolates had a mutation in the D-promoter. Parallelism was moderate compared to previous experiments with this system. On average, wells shared 27% of their mutations at the DNA level and 38% when the definition of parallel change is expanded to include the same regulatory feature or residue. About half of the parallelism came from D-promoter mutations. Background had a small but significant effect on parallelism. Similarly, an analyses of epistasis between mutations and their ancestral background was significant, but the result was mostly driven by four individual mutations. A second analysis of epistasis focused on de novo mutations revealed that no isolate ever had more than one D-promoter mutation and that 56 of the 65 isolates lacking a D-promoter mutation had a mutation in genes D and/or E. We assayed time to lysis in four of these mutually exclusive mutations (the two most frequent D-promoter and two in gene D) across four genetic backgrounds. In all cases lysis was delayed. We postulate that because host cells were generally rare (i.e., high multiplicity of infection conditions developed), selection favored phage that delayed lysis to better exploit their current host (i.e., ‘love the one you’re with’). Thus, the vast majority of wells (at least 64 of 68, or 94%) arrived at the same phenotypic solution, but through a variety of genetic changes. We conclude that answering questions about the range of possible adaptive trajectories, parallelism, and the predictability of evolution requires attention to the many biological levels where the process of adaptation plays out.

scholarly journals Noncoding de novo mutations contribute to autism spectrum disorder via chromatin interactions

2019 ◽  
Author(s):  
Il Bin Kim ◽  
Taeyeop Lee ◽  
Junehawk Lee ◽  
Jonghun Kim ◽  
Hyunseong Lee ◽  
...  
Keyword(s):  
Gene Expression ◽  
Autism Spectrum Disorder ◽  
Stem Cells ◽  
Target Genes ◽  
De Novo ◽  
Regulatory Elements ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
De Novo Mutations ◽  
Chromatin Interactions

Three-dimensional chromatin structures regulate gene expression across genome. The significance of de novo mutations (DNMs) affecting chromatin interactions in autism spectrum disorder (ASD) remains poorly understood. We generated 931 whole-genome sequences for Korean simplex families to detect DNMs and identified target genes dysregulated by noncoding DNMs via long-range chromatin interactions between regulatory elements. Notably, noncoding DNMs that affect chromatin interactions exhibited transcriptional dysregulation implicated in ASD risks. Correspondingly, target genes were significantly involved in histone modification, prenatal brain development, and pregnancy. Both noncoding and coding DNMs collectively contributed to low IQ in ASD. Indeed, noncoding DNMs resulted in alterations, via chromatin interactions, in target gene expression in primitive neural stem cells derived from human induced pluripotent stem cells from an ASD subject. The emerging neurodevelopmental genes, not previously implicated in ASD, include CTNNA2, GRB10, IKZF1, PDE3B, and BACE1. Our results were reproducible in 517 probands from MSSNG cohort. This work demonstrates that noncoding DNMs contribute to ASD via chromatin interactions.

scholarly journals De novo mutations in the GTP/GDP-binding region of RALA, a RAS-like small GTPase, cause intellectual disability and developmental delay

2018 ◽  
Author(s):  
Susan M. Hiatt ◽  
Matthew B. Neu ◽  
Ryne C. Ramaker ◽  
Andrew A. Hardigan ◽  
Jeremy W. Prokop ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
De Novo ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Facial Dysmorphism ◽  
De Novo Mutations ◽  
Binding Region ◽  
Gtp Hydrolysis ◽  
Genetic Changes ◽  
Developmental Problems

AbstractMutations that alter signaling of RAS/MAPK-family proteins give rise to a group of Mendelian diseases known as RASopathies, but the matrix of genotype-phenotype relationships is still incomplete, in part because there are many RAS-related proteins, and in part because the phenotypic consequences may be variable and/or pleiotropic. Here, we describe a cohort of ten cases, drawn from six clinical sites and over 16,000 sequenced probands, with de novo protein-altering variation in RALA, a RAS-like small GTPase. All probands present with speech and motor delays, and most have intellectual disability, low weight, short stature, and facial dysmorphism. The observed rate of de novo RALA variants in affected probands is significantly higher (p=4.93 × 10−11) than expected from the estimated mutation rate. Further, all de novo variants described here affect conserved residues within the GTP/GDP-binding region of RALA; in fact, six alleles arose at only two codons, Val25 and Lys128. We directly assayed GTP hydrolysis and RALA effector-protein binding, and all but one tested variant significantly reduced both activities. The one exception, S157A, reduced GTP hydrolysis but significantly increased RALA-effector binding, an observation similar to that seen for oncogenic RAS variants. These results show the power of data sharing for the interpretation and analysis of rare variation, expand the spectrum of molecular causes of developmental disability to include RALA, and provide additional insight into the pathogenesis of human disease caused by mutations in small GTPases.Author SummaryWhile many causes of developmental disabilities have been identified, a large number of affected children cannot be diagnosed despite extensive medical testing. Previously unknown genetic factors are likely to be the culprits in many of these cases. Using DNA sequencing, and by sharing information among many doctors and researchers, we have identified a set of individuals with developmental problems who all have changes to the same gene, RALA. The affected individuals all have similar symptoms, including intellectual disability, speech delay (or no speech), and problems with motor skills like walking. In nearly all of these cases (10 of 11), the genetic change found in the child was not inherited from either parent. The locations and biological properties of these changes suggest that they are likely to disrupt the normal functions of RALA and cause significant health problems. We also performed experiments to show that the genetic changes found in these individuals alter two key functions of RALA. Together, we have provided evidence that genetic changes in RALA can cause DD/ID. These results will allow doctors and researchers to identify additional children with the same condition, providing a clinical diagnosis to these families and leading to new research opportunities.

scholarly journals Collaboration Between Host and Viral Factors Shape SARS-CoV-2 Evolution

2021 ◽  
Author(s):  
Connor G G Bamford ◽  
Lindsay Broadbent ◽  
Elihu Aranday Cortes ◽  
Mary McCabe ◽  
James McKenna ◽  
...  
Keyword(s):  
Viral Evolution ◽  
Host Factors ◽  
Host Cells ◽  
Phenotypic Change ◽  
Human Respiratory Tract ◽  
Genetic Changes ◽  
Nasal Epithelial Cell ◽  
Host Cell Factors ◽  
Well Differentiated

SARS-CoV-2 continues to evolve, resulting in several variants of concern with novel properties. The factors driving SARS-CoV-2 fitness and evolution in the human respiratory tract remain poorly defined. Here, we provide evidence that both viral and host factors co-operate to shape SARS-CoV-2 genotypic and phenotypic change. Through viral whole genome sequencing, we explored the evolution of two clinical isolates of SARS CoV-2 during passage in unmodified Vero-derived cell lines and in parallel, in well-differentiated primary nasal epithelial cell (WD-PNEC) cultures. We identify a consistent, rich genetic diversity arising in vitro, variants of which could rapidly rise to near-fixation with 2 passages. Within isolates, SARS-CoV-2 evolution was dependent on host cells, with Vero-derived cells facilitating more profound genetic changes. However, most mutations were not shared between strains. Furthermore, comparison of both Vero-grown isolates on WD-PNECs disclosed marked growth attenuation mapping to the loss of the polybasic cleavage site (PBCS) in Spike while the strain with mutations in NSP12 (T293I), Spike (P812R) and a truncation of ORF7a remained viable in WD-PNECs. Our work highlights the significant genetic plasticity of SARS-CoV-2 while uncovering an influential role for collaboration between viral and host cell factors in shaping viral evolution and fitness in human respiratory epithelium.

scholarly journals A replication-linked mutational gradient drives somatic mutation accumulation and influences germline polymorphisms and genome composition in mitochondrial DNA

2021 ◽  
Author(s):  
Monica Sanchez-Contreras ◽  
Mariya T Sweetwyne ◽  
Brendan F Kohrn ◽  
Kristine A Tsantilas ◽  
Michael J Hipp ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Somatic Mutations ◽  
De Novo ◽  
Primary Source ◽  
Regulatory Elements ◽  
Genome Replication ◽  
Nucleotide Polymorphisms ◽  
De Novo Mutations ◽  
Genome Composition ◽  
Mtdna Mutations

Abstract Mutations in mitochondrial DNA (mtDNA) cause maternally inherited diseases, while somatic mutations are linked to common diseases of aging. Although mtDNA mutations impact health, the processes that give rise to them are under considerable debate. To investigate the mechanism by which de novo mutations arise, we analyzed the distribution of naturally occurring somatic mutations across the mouse and human mtDNA obtained by Duplex Sequencing. We observe distinct mutational gradients in G→A and T→C transitions delimited by the light-strand origin and the mitochondrial Control Region (mCR). The gradient increases unequally across the mtDNA with age and is lost in the absence of DNA polymerase γ proofreading activity. In addition, high-resolution analysis of the mCR shows that important regulatory elements exhibit considerable variability in mutation frequency, consistent with them being mutational ‘hot-spots’ or ‘cold-spots’. Collectively, these patterns support genome replication via a deamination prone asymmetric strand-displacement mechanism as the fundamental driver of mutagenesis in mammalian DNA. Moreover, the distribution of mtDNA single nucleotide polymorphisms in humans and the distribution of bases in the mtDNA across vertebrate species mirror this gradient, indicating that replication-linked mutations are likely the primary source of inherited polymorphisms that, over evolutionary timescales, influences genome composition during speciation.

scholarly journals Epstein-Barr virus inactivates the transcriptome and disrupts the chromatin architecture of its host cell in the first phase of lytic reactivation

2019 ◽  
Author(s):  
Alexander Buschle ◽  
Paulina Mrozek-Gorska ◽  
Stefan Krebs ◽  
Helmut Blum ◽  
Filippo M. Cernilogar ◽  
...  
Keyword(s):  
Host Cell ◽  
Epstein Barr Virus ◽  
De Novo ◽  
Human Tumor ◽  
Regulatory Elements ◽  
Lytic Cycle ◽  
Host Cells ◽  
Dependent Manner ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus (EBV), a herpes virus also termed HHV 4 and the first identified human tumor virus, establishes a stable long-term latent infection in human B cells, its preferred host. Upon induction of EBV’s lytic phase the latently infected cells turn into a virus factory, a process, that is governed by EBV. In the lytic, productive phase all herpesviruses ensure the efficient induction of all lytic viral genes to produce progeny, but certain of these genes also repress the ensuing antiviral responses of the virally infected host cells, regulate their apoptotic death or control the cellular transcriptome. We now find that EBV causes previously unknown massive and global alterations in the chromatin of its host cell upon induction of the viral lytic phase and prior to the onset of viral DNA replication. The viral initiator protein of the lytic cycle, BZLF1, binds to >105binding sites with different sequence motifs in cellular chromatin and in a concentration dependent manner. Concomitant with DNA binding, silent chromatin opens locally as shown by ATAC-seq experiments, while previously wide-open cellular chromatin becomes inaccessible on a global scale within hours. While viral transcripts increase drastically, the induction of the lytic phase results in a massive reduction of cellular transcripts and a loss of chromatin-chromatin interactions of cellular promoters with their distal regulatory elements as shown in Capture-C experiments. Our data document that EBV’s lytic cycle induces discrete early processes that disrupt the architecture of host cellular chromatin and repress the cellular epigenome and transcriptome likely supporting the efficientde novosynthesis of this herpesvirus.

CNV Analysis in Monozygotic Twin Pairs Discordant for Urorectal Malformations

2013 ◽  
Vol 16 (4) ◽  
pp. 802-807 ◽  
Author(s):  
Friederike Baudisch ◽  
Markus Draaken ◽  
Enrika Bartels ◽  
Eberhard Schmiedeke ◽  
Soyhan Bagci ◽  
...  
Keyword(s):  
De Novo ◽  
Bladder Exstrophy ◽  
Anorectal Malformations ◽  
Monozygotic Twin ◽  
Regulatory Elements ◽  
Copy Number Variations ◽  
Molecular Karyotyping ◽  
Genetic Changes ◽  
Coding Regions ◽  
Whole Exome

Early post-twinning mutational events can account for discordant phenotypes in monozygotic (MZ) twin pairs. Such mutational events may comprise genomic alterations of different sizes, ranging from single nucleotides to large copy-number variations (CNVs). Anorectal malformations (ARM) and the bladder exstrophy-epispadias complex (BEEC) represent the most severe end of the urorectal malformation spectrum. Recently, CNV studies in patients with sporadic ARM and the BEEC have identified de novo events that occur in specific chromosomal regions. We hypothesized that early arising, post-twinning CNVs might contribute to discordance in MZ twin pairs with ARM or the BEEC; knowledge of such CNVs might help to identify additional chromosomal regions involved in the development of these malformations. We investigated four discordant MZ twin pairs (three ARM and one BEEC) using molecular karyotyping arrays comprising 1,140,419 markers with a median marker spacing of 1.5 kb. Filtering the coding regions for possible disease-causing post-twinning de novo CNVs present only in the affected twin, but not in the unaffected twin or the parents, identified a total of 136 CNVs. These 136 CNVs were then filtered against publicly available databases and finally re-evaluated visually. No potentially causative CNV remained after applying these filter criteria. Our results suggest that post-twinning CNV events that affect coding regions of the genome did not contribute to the discordant phenotypes in MZ twin pairs that we investigated. Possible causes for the discordant phenotypes include changes in regulatory elements or smaller genetic changes within coding regions which may be detectable by whole-exome sequencing.

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