scholarly journals Temporal scaling of ageing as an adaptive strategy of Escherichia coli

2018 ◽  
Author(s):  
Yifan Yang ◽  
Ana L. Santos ◽  
Luping Xu ◽  
Chantal Lotton ◽  
François Taddei ◽  
...  
Keyword(s):  
Life History ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Life History Evolution ◽  
Time Lapse ◽  
Life History Trait ◽  
Human Populations ◽  
Hazard Functions ◽  
E Coli ◽  
Ageing Rate

AbstractNatural selection has long been hypothesised to shape ageing patterns, but whether and how ageing contributes to life-history evolution remains elusive. The complexity of various ageing-associated molecular mechanisms and their inherent stochasticity hinder reductionist approaches to the understanding of functional senescence, i.e. reduced fecundity and increased mortality. Recent bio-demographic work demonstrated that high-precision statistics of life-history traits such as mortality rates could be used phenomenologically to understand the ageing process. We adopted this approach to study cellular senescence in growth-arrested E. coli cells, where damages to functional macromolecules are no longer diluted by fast de novo biosynthesis. We acquired high-quality longitudinal physiological and life history data of large environmentally controlled clonal E. coli populations at single-cell resolution, using custom-designed microfluidic devices coupled to time-lapse microscopy. We show that E. coli lifespan distributions follow the Gompertz law of mortality, a century-old actuarial observation of human populations, despite developmental, cellular and genetic differences between bacteria and metazoan organisms. Measuring the shape of the hazard functions allowed us to disentangle quantitatively the demographic effects of ageing, which accumulate with time, from age-independent genetic longevity-modulating interventions. A pathway controlling cellular maintenance, the general stress response, not only promotes longevity but also temporally scales the whole distribution by reducing ageing rate. We further show that E. coli, constrained by the amount of total biosynthesis, adapt to their natural feast-or-famine lifestyle by modulating the amount of maintenance investment, rendering ageing rate a highly evolvable life-history trait.

scholarly journals The fast-slow continuum is not the end-game of life history evolution, human or otherwise

2021 ◽  
Author(s):  
Roberto Salguero-Gómez
Keyword(s):  
Life History ◽  
Life History Evolution ◽  
Principal Component ◽  
Population Level ◽  
Great Promise ◽  
Human Populations ◽  
Life History Variation ◽  
Stochastic Variation ◽  
Pace Of Life ◽  
Animal Populations

AbstractLife history human evolution places a strong emphasis on the fast-slow continuum and pace-of-life continuum. Papers in this area frequently make a call for more integrative research to explore the relationships between the fast-slow continuum (population-level variation in traits) and pace-of-life continuum (ditto at the individual level). Here, using high-resolution demographic models from natural populations of 41 modern human populations, and hundreds of non-human animal populations and plant populations, I show that the fast-slow continuum, while of interest to explore variation in human strategies, should not be the sole focus of attention. Using a phylogenetically corrected principal component analysis, I show that other axes of life history variation show great promise. Specifically, understanding of the mechanisms of inter-specific and intra-specific differences in senescence rates in reproduction and survival, and how species respond to stochastic variation, I argue, should become the focus of my interdisciplinary research. The proposed new axis of demographic buffering-lability emerges as an important one to explain over 20% of variation in human and non-human populations. I show that these axes help predict demographic resilience, and also correlates with human nation per capita GDP and population growth rates.

scholarly journals Estimating the evolution of human life history traits in age-structured populations

2014 ◽  
Author(s):  
Ryan Baldini
Keyword(s):  
Life History ◽  
Human Life ◽  
Life History Evolution ◽  
Selection Response ◽  
Structured Populations ◽  
Life History Trait ◽  
Vital Rates ◽  
Structured Population ◽  
Age Structured ◽  
Genetic Contributions

I propose a method that estimates the selection response of all vital rates in an age-structured population. I assume that vital rates are determined by the additive genetic contributions of many loci. The method uses all relatedness information in the sample to inform its estimates of genetic parameters, via an MCMC Bayesian framework. One can use the results to estimate the selection response of any life history trait that is a function of the vital rates, including the age at first reproduction, total lifetime fertility, survival to adulthood, and others. This method closely ties the empirical analysis of life history evolution to dynamically complete models of natural selection, and therefore enjoys some theoretical advantages over other methods. I demonstrate the method on a simulated model of evolution with two age classes. Finally I discuss how the method can be extended to more complicated cases.

scholarly journals Point mutations in topoisomerase I alter the mutation spectrum in E. coli and impact the emergence of drug resistance genotypes

2019 ◽  
Author(s):  
Amit Bachar ◽  
Elad Itzhaki ◽  
Shmuel Gleizer ◽  
Melina Shamshoom ◽  
Ron Milo ◽  
...  
Keyword(s):  
Topoisomerase I ◽  
Molecular Mechanisms ◽  
Tandem Repeats ◽  
De Novo ◽  
Point Mutations ◽  
High Rate ◽  
Mutation Spectrum ◽  
Adaptive Laboratory Evolution ◽  
E Coli ◽  
Topoisomerase 1

AbstractIdentifying the molecular mechanisms that give rise to genetic variation is essential for the understanding of evolutionary processes. Previously, we have used adaptive laboratory evolution to enable biomass synthesis from CO2 in E. coli. Genetic analysis of adapted clones from two independently evolving populations revealed distinct enrichment for insertion and deletion mutational events. Here, we follow these observations to show that mutations in the gene encoding for DNA Topoisomerase 1 (topA) give rise to mutator phenotypes with characteristic mutational spectra. Using genetic assays and mutation accumulation lines, we show that point mutations in topA increase the rate of sequence deletion and duplication events. Interestingly, we observe that a single residue substitution (R168C) results in a high rate of head-to-tail (tandem) short sequence duplications, which are independent of existing sequence repeats. Finally, we show that the unique mutation spectrum of topA mutants enhances the emergence of antibiotic resistance in comparison to mismatch-repair (mutS) mutators, and lead to new resistance genotypes. Our findings highlight a potential link between the catalytic activity of topoisomerases and the fundamental question regarding the emergence of de novo tandem repeats, which are known modulators of bacterial evolution.

scholarly journals Crop Fertilization Impacts Epidemics and Optimal Latent Period of Biotrophic Fungal Pathogens

2017 ◽  
Vol 107 (10) ◽  
pp. 1256-1267 ◽  
Author(s):  
Pierre-Antoine Précigout ◽  
David Claessen ◽  
Corinne Robert
Keyword(s):  
Life History ◽  
Latent Period ◽  
Fungal Pathogens ◽  
Negative Relationship ◽  
Agricultural Practices ◽  
Life History Evolution ◽  
Critical Issue ◽  
Spore Production ◽  
Life History Trait ◽  
Fertilization Level

Crop pathogens are known to rapidly adapt to agricultural practices. Although cultivar resistance breakdown and resistance to pesticides have been broadly studied, little is known about the adaptation of crop pathogens to fertilization regimes and no epidemiological model has addressed that question. However, this is a critical issue for developing sustainable low-input agriculture. In this article, we use a model of life history evolution of biotrophic wheat fungal pathogens in order to understand how they could adapt to changes in fertilization practices. We focus on a single pathogen life history trait, the latent period, which directly determines the amount of resources allocated to growth and reproduction along with the speed of canopy colonization. We implemented three fertilization scenarios, corresponding to major effects of increased nitrogen fertilization on crops: (i) increase in nutrient concentration in leaves, (ii) increase of leaf lifespan, and (iii) increase of leaf number (tillering) and size that leads to a bigger canopy size. For every scenario, we used two different fitness measures to identify putative evolutionary responses of latent period to changes in fertilization level. We observed that annual spore production increases with fertilization, because it results in more resources available to the pathogens. Thus, diminishing the use of fertilizers could reduce biotrophic fungal epidemics. We found a positive relationship between the optimal latent period and fertilization when maximizing total spore production over an entire season. In contrast, we found a negative relationship between the optimal latent period and fertilization when maximizing the within-season exponential growth rate of the pathogen. These contrasting results were consistent over the three tested fertilization scenarios. They suggest that between-strain diversity in the latent period, as has been observed in the field, may be due to diversifying selection in different cultural environments.

scholarly journals HP1 drives de novo 3D genome reorganization in early Drosophila embryos

Nature ◽  
2021 ◽  
Author(s):  
Fides Zenk ◽  
Yinxiu Zhan ◽  
Pavel Kos ◽  
Eva Löser ◽  
Nazerke Atinbayeva ◽  
...  
Keyword(s):  
Genome Organization ◽  
Molecular Mechanisms ◽  
High Throughput Sequencing ◽  
De Novo ◽  
Early Embryo ◽  
Heterochromatin Protein ◽  
Chromosome Conformation ◽  
3D Genome ◽  
Genome Reorganization

AbstractFundamental features of 3D genome organization are established de novo in the early embryo, including clustering of pericentromeric regions, the folding of chromosome arms and the segregation of chromosomes into active (A-) and inactive (B-) compartments. However, the molecular mechanisms that drive de novo organization remain unknown1,2. Here, by combining chromosome conformation capture (Hi-C), chromatin immunoprecipitation with high-throughput sequencing (ChIP–seq), 3D DNA fluorescence in situ hybridization (3D DNA FISH) and polymer simulations, we show that heterochromatin protein 1a (HP1a) is essential for de novo 3D genome organization during Drosophila early development. The binding of HP1a at pericentromeric heterochromatin is required to establish clustering of pericentromeric regions. Moreover, HP1a binding within chromosome arms is responsible for overall chromosome folding and has an important role in the formation of B-compartment regions. However, depletion of HP1a does not affect the A-compartment, which suggests that a different molecular mechanism segregates active chromosome regions. Our work identifies HP1a as an epigenetic regulator that is involved in establishing the global structure of the genome in the early embryo.

scholarly journals Production, characterization, and cross-reactivity of a polyclonal antibody against Arabidopsis TARGET OF RAPAMYCIN

2019 ◽  
Vol 62 (1) ◽  
Author(s):  
Gyeong-Im Shin ◽  
Sun Young Moon ◽  
Song Yi Jeong ◽  
Myung Geun Ji ◽  
Joon-Yung Cha ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Cross Reactivity ◽  
Target Of Rapamycin ◽  
Loss Of Function ◽  
Anticancer Activities ◽  
Purification Method ◽  
E Coli ◽  
Related Family ◽  
Large Gene ◽  
Truncated Variants

AbstractTARGET OF RAPAMYCIN (TOR), a member of the phosphatidylinositol 3-kinase-related family of protein kinases, is encoded by a single, large gene and is evolutionarily conserved in all eukaryotes. TOR plays a role as a master regulator that integrates nutrient, energy, and stress signaling to orchestrate development. TOR was first identified in yeast mutant screens, as its mutants conferred resistance to rapamycin, an antibiotic with immunosuppressive and anticancer activities. In Arabidopsis thaliana, the loss-of-function tor mutant displays embryo lethality, but the precise mechanisms of TOR function are still unknown. Moreover, a lack of reliable molecular and biochemical assay tools limits our ability to explore TOR functions in plants. Here, we produced a polyclonal α-TOR antibody using two truncated variants of TOR (1–200 and 1113–1304 amino acids) as antigens because recombinant full-length TOR is challenging to express in Escherichia coli. Recombinant His-TOR1−200 and His-TOR1113−1304 proteins were individually expressed in E. coli, and a mixture of proteins (at a 1:1 ratio) was used for immunizing rabbits. Antiserum was purified by an antigen-specific purification method, and the purified polyclonal α-TOR antibody successfully detected endogenous TOR proteins in wild-type Arabidopsis and TOR orthologous in major crop plants, including tomato, maize, and alfalfa. Moreover, our α-TOR antibody is useful for coimmunoprecipitation assays. In summary, we generated a polyclonal α-TOR antibody that detects endogenous TOR in various plant species. Our antibody could be used in future studies to determine the precise molecular mechanisms of TOR, which has largely unknown multifunctional roles in plants.

scholarly journals Mapping the adaptive landscape of a major agricultural pathogen reveals evolutionary constraints across heterogeneous environments

2021 ◽  
Author(s):  
Anik Dutta ◽  
Fanny E. Hartmann ◽  
Carolina Sardinha Francisco ◽  
Bruce A. McDonald ◽  
Daniel Croll
Keyword(s):  
Life History ◽  
Large Scale ◽  
Life History Traits ◽  
Genetic Correlations ◽  
Stress Factors ◽  
Life History Trait ◽  
Adaptive Landscape ◽  
Heterogeneous Environments ◽  
Growth Responses ◽  
Trade Offs

AbstractThe adaptive potential of pathogens in novel or heterogeneous environments underpins the risk of disease epidemics. Antagonistic pleiotropy or differential resource allocation among life-history traits can constrain pathogen adaptation. However, we lack understanding of how the genetic architecture of individual traits can generate trade-offs. Here, we report a large-scale study based on 145 global strains of the fungal wheat pathogen Zymoseptoria tritici from four continents. We measured 50 life-history traits, including virulence and reproduction on 12 different wheat hosts and growth responses to several abiotic stressors. To elucidate the genetic basis of adaptation, we used genome-wide association mapping coupled with genetic correlation analyses. We show that most traits are governed by polygenic architectures and are highly heritable suggesting that adaptation proceeds mainly through allele frequency shifts at many loci. We identified negative genetic correlations among traits related to host colonization and survival in stressful environments. Such genetic constraints indicate that pleiotropic effects could limit the pathogen’s ability to cause host damage. In contrast, adaptation to abiotic stress factors was likely facilitated by synergistic pleiotropy. Our study illustrates how comprehensive mapping of life-history trait architectures across diverse environments allows to predict evolutionary trajectories of pathogens confronted with environmental perturbations.

scholarly journals Copy number-dependent DNA methylation of the Pyricularia oryzae MAGGY retrotransposon is triggered by DNA damage

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ba Van Vu ◽  
Quyet Nguyen ◽  
Yuki Kondo-Takeoka ◽  
Toshiki Murata ◽  
Naoki Kadotani ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Copy Number ◽  
Rna Silencing ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Pyricularia Oryzae ◽  
Transcriptional Gene Silencing ◽  
Physical Interaction ◽  
Uncharacterized Protein ◽  
Form Complex

AbstractTransposable elements are common targets for transcriptional and post-transcriptional gene silencing in eukaryotic genomes. However, the molecular mechanisms responsible for sensing such repeated sequences in the genome remain largely unknown. Here, we show that machinery of homologous recombination (HR) and RNA silencing play cooperative roles in copy number-dependent de novo DNA methylation of the retrotransposon MAGGY in the fungusPyricularia oryzae. Genetic and physical interaction studies revealed thatRecAdomain-containing proteins, includingP. oryzaehomologs ofRad51, Rad55, andRad57, together with an uncharacterized protein, Ddnm1, form complex(es) and mediate either the overall level or the copy number-dependence of de novo MAGGY DNA methylation, likely in conjunction with DNA repair. Interestingly,P. oryzaemutants of specific RNA silencing components (MoDCL1andMoAGO2)were impaired in copy number-dependence of MAGGY methylation. Co-immunoprecipitation of MoAGO2 and HR components suggested a physical interaction between the HR and RNA silencing machinery in the process.

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