1
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Liu Y, LaBonte S, Brake C, LaFayette C, Rosebrock AP, Caudy AA, Straight PD. MOB rules: Antibiotic Exposure Reprograms Metabolism to Mobilize Bacillus subtilis in Competitive Interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.20.585991. [PMID: 38562742 PMCID: PMC10983992 DOI: 10.1101/2024.03.20.585991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Antibiotics have dose-dependent effects on exposed bacteria. The medicinal use of antibiotics relies on their growth-inhibitory activities at sufficient concentrations. At subinhibitory concentrations, exposure effects vary widely among different antibiotics and bacteria. Bacillus subtilis responds to bacteriostatic translation inhibitors by mobilizing a population of cells (MOB-Mobilized Bacillus) to spread across a surface. How B. subtilis regulates the antibiotic-induced mobilization is not known. In this study, we used chloramphenicol to identify regulatory functions that B. subtilis requires to coordinate cell mobilization following subinhibitory exposure. We measured changes in gene expression and metabolism and mapped the results to a network of regulatory proteins that direct the mobile response. Our data reveal that several transcriptional regulators coordinately control the reprogramming of metabolism to support mobilization. The network regulates changes in glycolysis, nucleotide metabolism, and amino acid metabolism that are signature features of the mobilized population. Among the hundreds of genes with changing expression, we identified two, pdhA and pucA, where the magnitudes of their changes in expression, and in the abundance of associated metabolites, reveal hallmark metabolic features of the mobilized population. Using reporters of pdhA and pucA expression, we visualized the separation of major branches of metabolism in different regions of the mobilized population. Our results reveal a regulated response to chloramphenicol exposure that enables a population of bacteria in different metabolic states to mount a coordinated mobile response.
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Affiliation(s)
- Yongjin Liu
- Biochemistry and Biophysics Department, Texas A&M University, AgriLife Research, College Station, Texas, USA
| | - Sandra LaBonte
- Biochemistry and Biophysics Department, Texas A&M University, AgriLife Research, College Station, Texas, USA
- Interdisciplinary Program in Genetics and Genomics,Texas A&M University, College Station, Texas, USA
| | - Courtney Brake
- Department of Visualization, Institute for Applied Creativity, Texas A&M University, College Station, Texas, USA
| | - Carol LaFayette
- Department of Visualization, Institute for Applied Creativity, Texas A&M University, College Station, Texas, USA
| | | | - Amy A. Caudy
- Maple Flavored Solutions, LLC, Indianapolis, Indiana, USA
| | - Paul D. Straight
- Biochemistry and Biophysics Department, Texas A&M University, AgriLife Research, College Station, Texas, USA
- Interdisciplinary Program in Genetics and Genomics,Texas A&M University, College Station, Texas, USA
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2
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Alexandre CM, Bubb KL, Schultz KM, Lempe J, Cuperus JT, Queitsch C. LTP2 hypomorphs show genotype-by-environment interaction in early seedling traits in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2024; 241:253-266. [PMID: 37865885 PMCID: PMC10843042 DOI: 10.1111/nph.19334] [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: 06/05/2023] [Accepted: 09/26/2023] [Indexed: 10/23/2023]
Abstract
Isogenic individuals can display seemingly stochastic phenotypic differences, limiting the accuracy of genotype-to-phenotype predictions. The extent of this phenotypic variation depends in part on genetic background, raising questions about the genes involved in controlling stochastic phenotypic variation. Focusing on early seedling traits in Arabidopsis thaliana, we found that hypomorphs of the cuticle-related gene LIPID TRANSFER PROTEIN 2 (LTP2) greatly increased variation in seedling phenotypes, including hypocotyl length, gravitropism and cuticle permeability. Many ltp2 hypocotyls were significantly shorter than wild-type hypocotyls while others resembled the wild-type. Differences in epidermal properties and gene expression between ltp2 seedlings with long and short hypocotyls suggest a loss of cuticle integrity as the primary determinant of the observed phenotypic variation. We identified environmental conditions that reveal or mask the increased variation in ltp2 hypomorphs and found that increased expression of its closest paralog LTP1 is necessary for ltp2 phenotypes. Our results illustrate how decreased expression of a single gene can generate starkly increased phenotypic variation in isogenic individuals in response to an environmental challenge.
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Affiliation(s)
| | - Kerry L Bubb
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
| | - Karla M Schultz
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
| | - Janne Lempe
- Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Institute for Breeding Research on Fruit Crops, Dresden, Germany 1099
| | - Josh T Cuperus
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
| | - Christine Queitsch
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA 98195, USA
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3
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Serrano M, Martins D, Henriques AO. Clostridioides difficile Sporulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1435:273-314. [PMID: 38175480 DOI: 10.1007/978-3-031-42108-2_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Some members of the Firmicutes phylum, including many members of the human gut microbiota, are able to differentiate a dormant and highly resistant cell type, the endospore (hereinafter spore for simplicity). Spore-formers can colonize virtually any habitat and, because of their resistance to a wide variety of physical and chemical insults, spores can remain viable in the environment for long periods of time. In the anaerobic enteric pathogen Clostridioides difficile the aetiologic agent is the oxygen-resistant spore, while the toxins produced by actively growing cells are the main cause of the disease symptoms. Here, we review the regulatory circuits that govern entry into sporulation. We also cover the role of spores in the infectious cycle of C. difficile in relation to spore structure and function and the main control points along spore morphogenesis.
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Affiliation(s)
- Mónica Serrano
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal.
| | - Diogo Martins
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal
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4
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Mertaoja A, Mascher G, Nowakowska MB, Korkeala H, Henriques AO, Lindstrom M. Cellular and population strategies underpinning neurotoxin production and sporulation in Clostridium botulinum type E cultures. mBio 2023; 14:e0186623. [PMID: 37971252 PMCID: PMC10746260 DOI: 10.1128/mbio.01866-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 10/06/2023] [Indexed: 11/19/2023] Open
Abstract
IMPORTANCE Toxin production and sporulation are key determinants of pathogenesis in Clostridia. Toxins cause the clinical manifestation of clostridial diseases, including diarrhea and colitis, tissue damage, and systemic effects on the nervous system. Spores ensure long-term survival and persistence in the environment, act as infectious agents, and initiate the host tissue colonization leading to infection. Understanding the interplay between toxin production and sporulation and their coordination in bacterial cells and cultures provides novel intervention points for controlling the public health and food safety risks caused by clostridial diseases. We demonstrate environmentally driven cellular heterogeneity in botulinum neurotoxin and spore production in Clostridium botulinum type E populations and discuss the biological rationale of toxin and spore production in the pathogenicity and ecology of C. botulinum. The results invite to reassess the epidemiology of botulism and may have important implications in the risk assessment and risk management strategies in food processing and human and animal health.
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Affiliation(s)
- Anna Mertaoja
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Gerald Mascher
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Maria B. Nowakowska
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Hannu Korkeala
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Adriano O. Henriques
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Miia Lindstrom
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
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5
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Alexandre CM, Bubb KL, Schultz KM, Lempe J, Cuperus JT, Queitsch C. LTP2 hypomorphs show genotype-by-environment interaction in early seedling traits in Arabidopsis thaliana. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.11.540469. [PMID: 37214854 PMCID: PMC10197655 DOI: 10.1101/2023.05.11.540469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Isogenic individuals can display seemingly stochastic phenotypic differences, limiting the accuracy of genotype-to-phenotype predictions. The extent of this phenotypic variation depends in part on genetic background, raising questions about the genes involved in controlling stochastic phenotypic variation. Focusing on early seedling traits in Arabidopsis thaliana, we found that hypomorphs of the cuticle-related gene LTP2 greatly increased variation in seedling phenotypes, including hypocotyl length, gravitropism and cuticle permeability. Many ltp2 hypocotyls were significantly shorter than wild-type hypocotyls while others resembled the wild type. Differences in epidermal properties and gene expression between ltp2 seedlings with long and short hypocotyls suggest a loss of cuticle integrity as the primary determinant of the observed phenotypic variation. We identified environmental conditions that reveal or mask the increased variation in ltp2 hypomorphs, and found that increased expression of its closest paralog LTP1 is necessary for ltp2 phenotypes. Our results illustrate how decreased expression of a single gene can generate starkly increased phenotypic variation in isogenic individuals in response to an environmental challenge.
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Affiliation(s)
| | - Kerry L Bubb
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
| | - Karla M Schultz
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
| | - Janne Lempe
- Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Institute for Breeding Research on Fruit Crops, Dresden, Germany
| | - Josh T Cuperus
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
| | - Christine Queitsch
- Department of Genome Sciences, University of Washington, Seattle WA 98195, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA 98195, USA
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6
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Parab L, Pal S, Dhar R. Transcription factor binding process is the primary driver of noise in gene expression. PLoS Genet 2022; 18:e1010535. [PMID: 36508455 PMCID: PMC9779669 DOI: 10.1371/journal.pgen.1010535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 12/22/2022] [Accepted: 11/16/2022] [Indexed: 12/14/2022] Open
Abstract
Noise in expression of individual genes gives rise to variations in activity of cellular pathways and generates heterogeneity in cellular phenotypes. Phenotypic heterogeneity has important implications for antibiotic persistence, mutation penetrance, cancer growth and therapy resistance. Specific molecular features such as the presence of the TATA box sequence and the promoter nucleosome occupancy have been associated with noise. However, the relative importance of these features in noise regulation is unclear and how well these features can predict noise has not yet been assessed. Here through an integrated statistical model of gene expression noise in yeast we found that the number of regulating transcription factors (TFs) of a gene was a key predictor of noise, whereas presence of the TATA box and the promoter nucleosome occupancy had poor predictive power. With an increase in the number of regulatory TFs, there was a rise in the number of cooperatively binding TFs. In addition, an increased number of regulatory TFs meant more overlaps in TF binding sites, resulting in competition between TFs for binding to the same region of the promoter. Through modeling of TF binding to promoter and application of stochastic simulations, we demonstrated that competition and cooperation among TFs could increase noise. Thus, our work uncovers a process of noise regulation that arises out of the dynamics of gene regulation and is not dependent on any specific transcription factor or specific promoter sequence.
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Affiliation(s)
- Lavisha Parab
- Department of Biotechnology, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, West Bengal, India
- Max-Planck-Institute for Evolutionary Biology, Plön, Germany
| | - Sampriti Pal
- Department of Biotechnology, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, West Bengal, India
| | - Riddhiman Dhar
- Department of Biotechnology, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, West Bengal, India
- * E-mail:
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7
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Koganezawa Y, Umetani M, Sato M, Wakamoto Y. History-dependent physiological adaptation to lethal genetic modification under antibiotic exposure. eLife 2022; 11:e74486. [PMID: 35535492 PMCID: PMC9090333 DOI: 10.7554/elife.74486] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 04/08/2022] [Indexed: 12/18/2022] Open
Abstract
Genetic modifications, such as gene deletion and mutations, could lead to significant changes in physiological states or even cell death. Bacterial cells can adapt to diverse external stresses, such as antibiotic exposure, but can they also adapt to detrimental genetic modification? To address this issue, we visualized the response of individual Escherichia coli cells to deletion of the antibiotic resistance gene under chloramphenicol (Cp) exposure, combining the light-inducible genetic recombination and microfluidic long-term single-cell tracking. We found that a significant fraction (∼40%) of resistance-gene-deleted cells demonstrated a gradual restoration of growth and stably proliferated under continuous Cp exposure without the resistance gene. Such physiological adaptation to genetic modification was not observed when the deletion was introduced in 10 hr or more advance before Cp exposure. Resistance gene deletion under Cp exposure disrupted the stoichiometric balance of ribosomal large and small subunit proteins (RplS and RpsB). However, the balance was gradually recovered in the cell lineages with restored growth. These results demonstrate that bacterial cells can adapt even to lethal genetic modifications by plastically gaining physiological resistance. However, the access to the resistance states is limited by the environmental histories and the timings of genetic modification.
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Affiliation(s)
- Yuta Koganezawa
- Department of Basic Science, Graduate School of Arts and Sciences, The University of TokyoMeguro-kuJapan
| | - Miki Umetani
- Department of Basic Science, Graduate School of Arts and Sciences, The University of TokyoMeguro-kuJapan
- Research Center for Complex Systems Biology, The University of TokyoTokyoJapan
| | - Moritoshi Sato
- Research Center for Complex Systems Biology, The University of TokyoTokyoJapan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of TokyoTokyoJapan
- Universal Biology Institute, The University of TokyoTokyoJapan
| | - Yuichi Wakamoto
- Department of Basic Science, Graduate School of Arts and Sciences, The University of TokyoMeguro-kuJapan
- Research Center for Complex Systems Biology, The University of TokyoTokyoJapan
- Universal Biology Institute, The University of TokyoTokyoJapan
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8
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Nantongo JS, Potts BM, Frickey T, Telfer E, Dungey H, Fitzgerald H, O'Reilly-Wapstra JM. Analysis of the transcriptome of the needles and bark of Pinus radiata induced by bark stripping and methyl jasmonate. BMC Genomics 2022; 23:52. [PMID: 35026979 PMCID: PMC8759178 DOI: 10.1186/s12864-021-08231-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 11/30/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plants are attacked by diverse insect and mammalian herbivores and respond with different physical and chemical defences. Transcriptional changes underlie these phenotypic changes. Simulated herbivory has been used to study the transcriptional and other early regulation events of these plant responses. In this study, constitutive and induced transcriptional responses to artificial bark stripping are compared in the needles and the bark of Pinus radiata to the responses from application of the plant stressor, methyl jasmonate. The time progression of the responses was assessed over a 4-week period. RESULTS Of the 6312 unique transcripts studied, 86.6% were differentially expressed between the needles and the bark prior to treatment. The most abundant constitutive transcripts were related to defence and photosynthesis and their expression did not differ between the needles and the bark. While no differential expression of transcripts were detected in the needles following bark stripping, in the bark this treatment caused an up-regulation and down-regulation of genes associated with primary and secondary metabolism. Methyl jasmonate treatment caused differential expression of transcripts in both the bark and the needles, with individual genes related to primary metabolism more responsive than those associated with secondary metabolism. The up-regulation of genes related to sugar break-down and the repression of genes related with photosynthesis, following both treatments was consistent with the strong down-regulation of sugars that has been observed in the same population. Relative to the control, the treatments caused a differential expression of genes involved in signalling, photosynthesis, carbohydrate and lipid metabolism as well as defence and water stress. However, non-overlapping transcripts were detected between the needles and the bark, between treatments and at different times of assessment. Methyl jasmonate induced more transcriptional responses in the bark than bark stripping, although the peak of expression following both treatments was detected 7 days post treatment application. The effects of bark stripping were localised, and no systemic changes were detected in the needles. CONCLUSION There are constitutive and induced differences in the needle and bark transcriptome of Pinus radiata. Some expression responses to bark stripping may differ from other biotic and abiotic stresses, which contributes to the understanding of plant molecular responses to diverse stresses. Whether the gene expression changes are heritable and how they differ between resistant and susceptible families identified in earlier studies needs further investigation.
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Affiliation(s)
- J S Nantongo
- School of Natural Sciences, University of Tasmania, Private Bag 5, Hobart, Tasmania, 7001, Australia.
- National Forestry Resources Research Institute, Mukono, Uganda.
| | - B M Potts
- School of Natural Sciences, University of Tasmania, Private Bag 5, Hobart, Tasmania, 7001, Australia
- ARC Training Centre for Forest Value, Hobart, Tasmania, Australia
| | | | | | | | - H Fitzgerald
- School of Natural Sciences, University of Tasmania, Private Bag 5, Hobart, Tasmania, 7001, Australia
| | - J M O'Reilly-Wapstra
- School of Natural Sciences, University of Tasmania, Private Bag 5, Hobart, Tasmania, 7001, Australia
- ARC Training Centre for Forest Value, Hobart, Tasmania, Australia
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9
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Espinosa-Soto C, Hernández U, Posadas-García YS. Recombination facilitates genetic assimilation of new traits in gene regulatory networks. Evol Dev 2021; 23:459-473. [PMID: 34455697 DOI: 10.1111/ede.12391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/11/2021] [Accepted: 08/04/2021] [Indexed: 11/30/2022]
Abstract
A new phenotypic variant may appear first in organisms through plasticity, that is, as a response to an environmental signal or other nongenetic perturbation. If such trait is beneficial, selection may increase the frequency of alleles that enable and facilitate its development. Thus, genes may take control of such traits, decreasing dependence on nongenetic disturbances, in a process called genetic assimilation. Despite an increasing amount of empirical studies supporting genetic assimilation, its significance is still controversial. Whether genetic assimilation is widespread depends, to a great extent, on how easily mutation and recombination reduce the trait's dependence on nongenetic perturbations. Previous research suggests that this is the case for mutations. Here we use simulations of gene regulatory network dynamics to address this issue with respect to recombination. We find that recombinant offspring of parents that produce a new phenotype through plasticity are more likely to produce the same phenotype without requiring any perturbation. They are also prone to preserve the ability to produce that phenotype after genetic and nongenetic perturbations. Our work also suggests that ancestral plasticity can play an important role for setting the course that evolution takes. In sum, our results indicate that the manner in which phenotypic variation maps unto genetic variation facilitates evolution through genetic assimilation in gene regulatory networks. Thus, we contend that the importance of this evolutionary mechanism should not be easily neglected.
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Affiliation(s)
- Carlos Espinosa-Soto
- Instituto de Física, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Ulises Hernández
- Instituto de Física, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
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10
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Myer C, Abdelrahman L, Banerjee S, Khattri RB, Merritt ME, Junk AK, Lee RK, Bhattacharya SK. Aqueous humor metabolite profile of pseudoexfoliation glaucoma is distinctive. Mol Omics 2021; 16:425-435. [PMID: 32149291 DOI: 10.1039/c9mo00192a] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Pseudoexfoliation (PEX) is a known cause of secondary open angle glaucoma. PEX glaucoma is associated with structural and metabolic changes in the eye. Despite similarities, PEX and primary open angle glaucoma (POAG) may have differences in the composition of metabolites. We analyzed the metabolites of the aqueous humor (AH) of PEX subjects sequentially first using nuclear magnetic resonance (1H NMR: HSQC and TOCSY), and subsequently with liquid chromatography tandem mass spectrometry (LC-MS/MS) implementing isotopic ratio outlier analysis (IROA) quantification. The findings were compared with previous results for POAG and control subjects analyzed using identical sequential steps. We found significant differences in metabolites between the three conditions. Principle component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) indicated clear grouping based on the metabolomes of the three conditions. We used machine learning algorithms and a percentage set of the data to train, and utilized a different or larger dataset to test whether a trained model can correctly classify the test dataset as PEX, POAG or control. Three different algorithms: linear support vector machines (SVM), deep learning, and a neural network were used for prediction. They all accurately classified the test datasets based on the AH metabolome of the sample. We next compared the AH metabolome with known AH and TM proteomes and genomes in order to understand metabolic pathways that may contribute to alterations in the AH metabolome in PEX. We found potential protein/gene pathways associated with observed significant metabolite changes in PEX.
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Affiliation(s)
- Ciara Myer
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
| | - Leila Abdelrahman
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
| | - Santanu Banerjee
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA and Department of Surgery, University of Miami, Miami, Florida, USA
| | | | | | - Anna K Junk
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA and Miami Veterans Affairs Healthcare System, Miami, Florida, USA
| | - Richard K Lee
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
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11
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Schwall CP, Loman TE, Martins BMC, Cortijo S, Villava C, Kusmartsev V, Livesey T, Saez T, Locke JCW. Tunable phenotypic variability through an autoregulatory alternative sigma factor circuit. Mol Syst Biol 2021; 17:e9832. [PMID: 34286912 PMCID: PMC8287880 DOI: 10.15252/msb.20209832] [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: 07/03/2020] [Revised: 05/28/2021] [Accepted: 06/01/2021] [Indexed: 11/17/2022] Open
Abstract
Genetically identical individuals in bacterial populations can display significant phenotypic variability. This variability can be functional, for example by allowing a fraction of stress prepared cells to survive an otherwise lethal stress. The optimal fraction of stress prepared cells depends on environmental conditions. However, how bacterial populations modulate their level of phenotypic variability remains unclear. Here we show that the alternative sigma factor σV circuit in Bacillus subtilis generates functional phenotypic variability that can be tuned by stress level, environmental history and genetic perturbations. Using single-cell time-lapse microscopy and microfluidics, we find the fraction of cells that immediately activate σV under lysozyme stress depends on stress level and on a transcriptional memory of previous stress. Iteration between model and experiment reveals that this tunability can be explained by the autoregulatory feedback structure of the sigV operon. As predicted by the model, genetic perturbations to the operon also modulate the response variability. The conserved sigma-anti-sigma autoregulation motif is thus a simple mechanism for bacterial populations to modulate their heterogeneity based on their environment.
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Affiliation(s)
| | | | - Bruno M C Martins
- Sainsbury LaboratoryUniversity of CambridgeCambridgeUK
- School of Life SciencesUniversity of WarwickCoventryUK
| | | | | | | | - Toby Livesey
- Sainsbury LaboratoryUniversity of CambridgeCambridgeUK
| | - Teresa Saez
- Sainsbury LaboratoryUniversity of CambridgeCambridgeUK
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12
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Gu X. Random Penetrance of Mutations Among Individuals: A New Type of Genetic Drift in Molecular Evolution. PHENOMICS (CHAM, SWITZERLAND) 2021; 1:105-112. [PMID: 36939798 PMCID: PMC9590493 DOI: 10.1007/s43657-021-00013-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/04/2021] [Accepted: 04/12/2021] [Indexed: 06/18/2023]
Abstract
The determinative view of mutation penetrance is a fundamental assumption for the building of molecular evolutionary theory: individuals in the population with the same genotype have the same fitness effect. Since this view has been constantly challenged by experimental evidence, it is desirable to examine to what extent violation of this view could affect our understanding of molecular evolution. To this end, the author formulated a new theory of molecular evolution under a random model of penetrance: for any individual with the same mutational genotype, the coefficient of selection is a random variable. It follows that, in addition to the conventional N e-genetic drift (N e is the effective population size), the variance of penetrance among individuals (ε 2) represents a new type of genetic drift, coined by the ε 2-genetic drift. It has been demonstrated that these two genetic drifts together provided new insights on the nearly neutral evolution: the evolutionary rate is inversely related to the log-of-N e when the ε 2-genetic drift is nontrivial. This log-of-N e feature of ε 2-genetic drift did explain well why the d N /d S ratio (the nonsynonymous rate to the synonymous rate) in humans is only as twofold as that in mice, while the effective population size (N e) of mice is about two-magnitude larger than that of humans. It was estimated that, for the first time, the variance of random penetrance in mammalian genes was approximately ε 2 ≈ 5.89 × 10-3.
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Affiliation(s)
- Xun Gu
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011 USA
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13
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Angert ER. Challenges Faced by Highly Polyploid Bacteria with Limits on DNA Inheritance. Genome Biol Evol 2021; 13:6156627. [PMID: 33677487 PMCID: PMC8245194 DOI: 10.1093/gbe/evab037] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2021] [Indexed: 12/11/2022] Open
Abstract
Most studies of bacterial reproduction have centered on organisms that undergo binary fission. In these models, complete chromosome copies are segregated with great fidelity into two equivalent offspring cells. All genetic material is passed on to offspring, including new mutations and horizontally acquired sequences. However, some bacterial lineages employ diverse reproductive patterns that require management and segregation of more than two chromosome copies. Epulopiscium spp., and their close relatives within the Firmicutes phylum, are intestinal symbionts of surgeonfish (family Acanthuridae). Each of these giant (up to 0.6 mm long), cigar-shaped bacteria contains tens of thousands of chromosome copies. Epulopiscium spp. do not use binary fission but instead produce multiple intracellular offspring. Only ∼1% of the genetic material in an Epulopiscium sp. type B mother cell is directly inherited by its offspring cells. And yet, even in late stages of offspring development, mother-cell chromosome copies continue to replicate. Consequently, chromosomes take on a somatic or germline role. Epulopiscium sp. type B is a strict anaerobe and while it is an obligate symbiont, its host has a facultative association with this intestinal microorganism. Therefore, Epulopiscium sp. type B populations face several bottlenecks that could endanger their diversity and resilience. Multilocus sequence analyses revealed that recombination is important to diversification in populations of Epulopiscium sp. type B. By employing mechanisms common to others in the Firmicutes, the coordinated timing of mother-cell lysis, offspring development and congression may facilitate the substantial recombination observed in Epulopiscium sp. type B populations.
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14
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Kuwahara H, Gao X. Stable maintenance of hidden switches as a strategy to increase the gene expression stability. NATURE COMPUTATIONAL SCIENCE 2021; 1:62-70. [PMID: 38217152 DOI: 10.1038/s43588-020-00001-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 11/02/2020] [Indexed: 01/15/2024]
Abstract
In response to severe genetic and environmental perturbations, wild-type organisms can express hidden alternative phenotypes adaptive to such adverse conditions. While our theoretical understanding of the population-level fitness advantage and evolution of phenotypic switching under variable environments has grown, the mechanism by which these organisms maintain phenotypic switching capabilities under static environments remains to be elucidated. Here, using computational simulations, we analyzed the evolution of gene circuits under natural selection and found that different strategies evolved to increase the gene expression stability near the optimum level. In a population comprising bistable individuals, a strategy of maintaining bistability and raising the potential barrier separating the bistable regimes was consistently taken. Our results serve as evidence that hidden bistable switches can be stably maintained during environmental stasis-an essential property enabling the timely release of adaptive alternatives with small genetic changes in the event of substantial perturbations.
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Affiliation(s)
- Hiroyuki Kuwahara
- Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Xin Gao
- Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
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15
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Maire T, Allertz T, Betjes MA, Youk H. Dormancy-to-death transition in yeast spores occurs due to gradual loss of gene-expressing ability. Mol Syst Biol 2020; 16:e9245. [PMID: 33206464 PMCID: PMC7673291 DOI: 10.15252/msb.20199245] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 11/28/2022] Open
Abstract
Dormancy is colloquially considered as extending lifespan by being still. Starved yeasts form dormant spores that wake-up (germinate) when nutrients reappear but cannot germinate (die) after some time. What sets their lifespans and how they age are open questions because what processes occur-and by how much-within each dormant spore remains unclear. With single-cell-level measurements, we discovered how dormant yeast spores age and die: spores have a quantifiable gene-expressing ability during dormancy that decreases over days to months until it vanishes, causing death. Specifically, each spore has a different probability of germinating that decreases because its ability to-without nutrients-express genes decreases, as revealed by a synthetic circuit that forces GFP expression during dormancy. Decreasing amounts of molecules required for gene expression-including RNA polymerases-decreases gene-expressing ability which then decreases chances of germinating. Spores gradually lose these molecules because they are produced too slowly compared with their degradations, causing gene-expressing ability to eventually vanish and, thus, death. Our work provides a systems-level view of dormancy-to-death transition.
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Affiliation(s)
- Théo Maire
- Kavli Institute of NanoscienceDelftThe Netherlands
- Department of BionanoscienceDelft University of TechnologyDelftThe Netherlands
| | - Tim Allertz
- Kavli Institute of NanoscienceDelftThe Netherlands
- Department of BionanoscienceDelft University of TechnologyDelftThe Netherlands
| | - Max A Betjes
- Kavli Institute of NanoscienceDelftThe Netherlands
- Department of BionanoscienceDelft University of TechnologyDelftThe Netherlands
| | - Hyun Youk
- Kavli Institute of NanoscienceDelftThe Netherlands
- CIFARCIFAR Azrieli Global Scholars ProgramTorontoONCanada
- Program in Molecular MedicineUniversity of Massachusetts Medical SchoolWorcesterMAUSA
- Program in Systems BiologyUniversity of Massachusetts Medical SchoolWorcesterMAUSA
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16
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Knuuttila T, García Deister V. Modelling gene regulation: (De)compositional and template-based strategies. STUDIES IN HISTORY AND PHILOSOPHY OF SCIENCE 2019; 77:101-111. [PMID: 31701873 DOI: 10.1016/j.shpsa.2017.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 10/16/2017] [Accepted: 11/06/2017] [Indexed: 06/10/2023]
Abstract
Although the interdisciplinary nature of contemporary biological sciences has been addressed by philosophers, historians, and sociologists of science, the different ways in which engineering concepts and methods have been applied in biology have been somewhat neglected. We examine - using the mechanistic philosophy of science as an analytic springboard - the transfer of network methods from engineering to biology through the cases of two biology laboratories operating at the California Institute of Technology. The two laboratories study gene regulatory networks, but in remarkably different ways. The research strategy of the Davidson lab fits squarely into the traditional mechanist philosophy in its aim to decompose and reconstruct, in detail, gene regulatory networks of a chosen model organism. In contrast, the Elowitz lab constructs minimal models that do not attempt to represent any particular naturally evolved genetic circuits. Instead, it studies the principles of gene regulation through a template-based approach that is applicable to any kinds of networks, whether biological or not. We call for the mechanists to consider whether the latter approach can be accommodated by the mechanistic approach, and what kinds of modifications it would imply for the mechanistic paradigm of explanation, if it were to address modelling more generally.
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Affiliation(s)
- Tarja Knuuttila
- University of South Carolina, University of Helsinki, 901 Sumter St., Byrnes Suite, Columbia, SC, 29208, USA.
| | - Vivette García Deister
- National Autonomous University of Mexico, Circuito Exterior, Cd. Universitaria, Copilco, Coyoacán, 04510 CDMX, Mexico.
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17
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Schmiedel JM, Carey LB, Lehner B. Empirical mean-noise fitness landscapes reveal the fitness impact of gene expression noise. Nat Commun 2019; 10:3180. [PMID: 31320634 PMCID: PMC6639414 DOI: 10.1038/s41467-019-11116-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/21/2019] [Indexed: 12/23/2022] Open
Abstract
The effects of cell-to-cell variation (noise) in gene expression have proven difficult to quantify because of the mechanistic coupling of noise to mean expression. To independently quantify the effects of changes in mean expression and noise we determine the fitness landscapes in mean-noise expression space for 33 genes in yeast. For most genes, short-lived (noise) deviations away from the expression optimum are nearly as detrimental as sustained (mean) deviations. Fitness landscapes can be classified by a combination of each gene’s sensitivity to protein shortage or surplus. We use this classification to explore evolutionary scenarios for gene expression and find that certain landscape topologies can break the mechanistic coupling of mean and noise, thus promoting independent optimization of both properties. These results demonstrate that noise is detrimental for many genes and reveal non-trivial consequences of mean-noise-fitness topologies for the evolution of gene expression systems. Quantifying the effects of noise in gene expression is difficult since noise and mean expression are coupled. Here the authors determine fitness landscapes in mean-noise expression space to uncouple these two parameters and show that changes in noise and mean expression are similarly detrimental to fitness.
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Affiliation(s)
- Jörn M Schmiedel
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Doctor Aiguader 88, 08003, Barcelona, Spain.
| | - Lucas B Carey
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Doctor Aiguader 88, 08003, Barcelona, Spain.,Center for Quantitative Biology and Peking-Tsinghua Center for the Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Ben Lehner
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Doctor Aiguader 88, 08003, Barcelona, Spain. .,Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain. .,ICREA, Passeig Lluís Companys 23, 08010, Barcelona, Spain.
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18
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Dhar R, Missarova AM, Lehner B, Carey LB. Single cell functional genomics reveals the importance of mitochondria in cell-to-cell phenotypic variation. eLife 2019; 8:38904. [PMID: 30638445 PMCID: PMC6366901 DOI: 10.7554/elife.38904] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 01/13/2019] [Indexed: 12/12/2022] Open
Abstract
Mutations frequently have outcomes that differ across individuals, even when these individuals are genetically identical and share a common environment. Moreover, individual microbial and mammalian cells can vary substantially in their proliferation rates, stress tolerance, and drug resistance, with important implications for the treatment of infections and cancer. To investigate the causes of cell-to-cell variation in proliferation, we used a high-throughput automated microscopy assay to quantify the impact of deleting >1500 genes in yeast. Mutations affecting mitochondria were particularly variable in their outcome. In both mutant and wild-type cells mitochondrial membrane potential - but not amount - varied substantially across individual cells and predicted cell-to-cell variation in proliferation, mutation outcome, stress tolerance, and resistance to a clinically used anti-fungal drug. These results suggest an important role for cell-to-cell variation in the state of an organelle in single cell phenotypic variation.
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Affiliation(s)
- Riddhiman Dhar
- Systems Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain.,Department of Biotechnology, Indian Institute of Technology, Kharagpur, India
| | - Alsu M Missarova
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Ben Lehner
- Systems Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Lucas B Carey
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
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19
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Merkuri F, Fish JL. Developmental processes regulate craniofacial variation in disease and evolution. Genesis 2018; 57:e23249. [PMID: 30207415 DOI: 10.1002/dvg.23249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/29/2018] [Accepted: 09/06/2018] [Indexed: 12/30/2022]
Abstract
Variation in development mediates phenotypic differences observed in evolution and disease. Although the mechanisms underlying phenotypic variation are still largely unknown, recent research suggests that variation in developmental processes may play a key role. Developmental processes mediate genotype-phenotype relationships and consequently play an important role regulating phenotypes. In this review, we provide an example of how shared and interacting developmental processes may explain convergence of phenotypes in spliceosomopathies and ribosomopathies. These data also suggest a shared pathway to disease treatment. We then discuss three major mechanisms that contribute to variation in developmental processes: genetic background (gene-gene interactions), gene-environment interactions, and developmental stochasticity. Finally, we comment on evolutionary alterations to developmental processes, and the evolution of disease buffering mechanisms.
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Affiliation(s)
- Fjodor Merkuri
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, Massachusetts
| | - Jennifer L Fish
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, Massachusetts
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20
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Rosenthal AZ, Qi Y, Hormoz S, Park J, Li SHJ, Elowitz MB. Metabolic interactions between dynamic bacterial subpopulations. eLife 2018; 7:33099. [PMID: 29809139 PMCID: PMC6025961 DOI: 10.7554/elife.33099] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/21/2018] [Indexed: 01/08/2023] Open
Abstract
Individual microbial species are known to occupy distinct metabolic niches within multi-species communities. However, it has remained largely unclear whether metabolic specialization can similarly occur within a clonal bacterial population. More specifically, it is not clear what functions such specialization could provide and how specialization could be coordinated dynamically. Here, we show that exponentially growing Bacillus subtilis cultures divide into distinct interacting metabolic subpopulations, including one population that produces acetate, and another population that differentially expresses metabolic genes for the production of acetoin, a pH-neutral storage molecule. These subpopulations exhibit distinct growth rates and dynamic interconversion between states. Furthermore, acetate concentration influences the relative sizes of the different subpopulations. These results show that clonal populations can use metabolic specialization to control the environment through a process of dynamic, environmentally-sensitive state-switching. The chemical reactions that occur within a living organism are collectively referred to as its metabolism. Many metabolic reactions produce byproducts that will poison the cells if they are not dealt with: fermenting bacteria, for example, release harmful organic acids and alcohols. How the bacteria respond to these toxins has been most studied at the level of entire microbial populations, meaning the activities of individual cells are effectively “averaged” together. Yet, even two bacteria with the same genes and living in the same environment can behave in different ways. This raises the question: do bacterial populations specialize into distinct subpopulations that play distinct roles when dealing with metabolic products, or do all cells in the community act in unison? Rosenthal et al. set out to answer this question for a community of Bacillus subtilis, a bacterium that is commonly studied in the laboratory and used for the industrial production of enzymes. The analysis focused on genes involved in fundamental metabolic processes, known as the TCA cycle, which the bacteria use to generate energy and build biomass. The experiments revealed that, even when all the cells are genetically identical, different Bacillus subtilis cells do indeed specialize into metabolic subpopulations with distinct growth rates. Time-lapse movies of bacteria that made fluorescent markers of different colors whenever certain metabolic genes became active showed cells switching different colors on and off, indicating that they switch between metabolic subpopulations. Further biochemical studies and measures of gene activity revealed that the different subpopulations produce and release distinct metabolic products, including toxic byproducts. Notably, the release of these metabolites by one subpopulation appeared to activate other subpopulations within the community. This example of cells specializing into unique interacting metabolic subpopulations provides insight into several fundamental issues in microbiology and beyond. It is relevant to evolutionary biologists, since the fact that fractions of the population can switch in and out of a metabolic state, instead of evolving into several inflexible specialists, may provide an evolutionary advantage in fluctuating natural environments by reducing the risk of extinction. It also has implications for industrial fermentation processes and metabolic engineering, and may help biotechnologists design more efficient ways to harness bacterial metabolism to produce useful products.
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Affiliation(s)
- Adam Z Rosenthal
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.,Department of Applied Physics, California Institute of Technology, Pasadena, United States
| | - Yutao Qi
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.,Department of Applied Physics, California Institute of Technology, Pasadena, United States
| | - Sahand Hormoz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.,Department of Applied Physics, California Institute of Technology, Pasadena, United States
| | - Jin Park
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.,Department of Applied Physics, California Institute of Technology, Pasadena, United States
| | - Sophia Hsin-Jung Li
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Michael B Elowitz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.,Department of Applied Physics, California Institute of Technology, Pasadena, United States.,Howard Hughes Medical Institute, Pasadena, United States
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21
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Park J, Dies M, Lin Y, Hormoz S, Smith-Unna SE, Quinodoz S, Hernández-Jiménez MJ, Garcia-Ojalvo J, Locke JCW, Elowitz MB. Molecular Time Sharing through Dynamic Pulsing in Single Cells. Cell Syst 2018; 6:216-229.e15. [PMID: 29454936 PMCID: PMC6070344 DOI: 10.1016/j.cels.2018.01.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 09/04/2017] [Accepted: 01/10/2018] [Indexed: 11/19/2022]
Abstract
In cells, specific regulators often compete for limited amounts of a core enzymatic resource. It is typically assumed that competition leads to partitioning of core enzyme molecules among regulators at constant levels. Alternatively, however, different regulatory species could time share, or take turns utilizing, the core resource. Using quantitative time-lapse microscopy, we analyzed sigma factor activity dynamics, and their competition for RNA polymerase, in individual Bacillus subtilis cells under energy stress. Multiple alternative sigma factors were activated in ~1-hr pulses in stochastic and repetitive fashion. Pairwise analysis revealed that two sigma factors rarely pulse simultaneously and that some pairs are anti-correlated, indicating that RNAP utilization alternates among different sigma factors. Mathematical modeling revealed how stochastic time-sharing dynamics can emerge from pulse-generating sigma factor regulatory circuits actively competing for RNAP. Time sharing provides a mechanism for cells to dynamically control the distribution of cell states within a population. Since core molecular components are limiting in many other systems, time sharing may represent a general mode of regulation.
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Affiliation(s)
- Jin Park
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Marta Dies
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona Biomedical Research Park, 08003 Barcelona, Spain; Department of Physics and Nuclear Engineering, Universitat Politecnica de Catalunya, 08222 Terrassa, Spain; Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA
| | - Yihan Lin
- Center for Quantitative Biology, and Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Sahand Hormoz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | | | - Sofia Quinodoz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | | | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona Biomedical Research Park, 08003 Barcelona, Spain.
| | - James C W Locke
- Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK; Microsoft Research, Cambridge, UK.
| | - Michael B Elowitz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.
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22
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Faure AJ, Schmiedel JM, Lehner B. Systematic Analysis of the Determinants of Gene Expression Noise in Embryonic Stem Cells. Cell Syst 2017; 5:471-484.e4. [DOI: 10.1016/j.cels.2017.10.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/06/2017] [Accepted: 10/02/2017] [Indexed: 01/23/2023]
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23
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Abstract
The interaction between the host and the pathogen is extremely complex and is affected by anatomical, physiological, and immunological diversity in the microenvironments, leading to phenotypic diversity of the pathogen. Phenotypic heterogeneity, defined as nongenetic variation observed in individual members of a clonal population, can have beneficial consequences especially in fluctuating stressful environmental conditions. This is all the more relevant in infections caused by Mycobacterium tuberculosis wherein the pathogen is able to survive and often establish a lifelong persistent infection in the host. Recent studies in tuberculosis patients and in animal models have documented the heterogeneous and diverging trajectories of individual lesions within a single host. Since the fate of the individual lesions appears to be determined by the local tissue environment rather than systemic response of the host, studying this heterogeneity is very relevant to ensure better control and complete eradication of the pathogen from individual lesions. The heterogeneous microenvironments greatly enhance M. tuberculosis heterogeneity influencing the growth rates, metabolic potential, stress responses, drug susceptibility, and eventual lesion resolution. Single-cell approaches such as time-lapse microscopy using microfluidic devices allow us to address cell-to-cell variations that are often lost in population-average measurements. In this review, we focus on some of the factors that could be considered as drivers of phenotypic heterogeneity in M. tuberculosis as well as highlight some of the techniques that are useful in addressing this issue.
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24
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Boross G, Papp B. No Evidence That Protein Noise-Induced Epigenetic Epistasis Constrains Gene Expression Evolution. Mol Biol Evol 2017; 34:380-390. [PMID: 28025271 DOI: 10.1093/molbev/msw236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Changes in gene expression can affect phenotypes and therefore both its level and stochastic variability are frequently under selection. It has recently been proposed that epistatic interactions influence gene expression evolution: gene pairs where simultaneous knockout is more deleterious than expected should evolve reduced expression noise to avoid concurrent low expression of both proteins. In apparent support, yeast genes with many epistatic partners have low expression variation both among isogenic individuals and between species. However, the specific predictions and basic assumptions of this verbal model remain untested. Using bioinformatics analysis, we first demonstrate that the model's predictions are unsupported by available large-scale data. Based on quantitative biochemical modeling, we then show that epistasis between expression reductions (epigenetic epistasis) is not expected to aggravate the fitness cost of stochastic expression, which is in sharp contrast to the verbal argument. This nonintuitive result can be readily explained by the typical diminishing return of fitness on gene activity and by the fact that expression noise not only decreases but also increases the abundance of proteins. Overall, we conclude that stochastic variation in epistatic partners is unlikely to drive noise minimization or constrain gene expression divergence on a genomic scale.
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Affiliation(s)
- Gábor Boross
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - Balázs Papp
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
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25
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Slager J, Veening JW. Hard-Wired Control of Bacterial Processes by Chromosomal Gene Location. Trends Microbiol 2016; 24:788-800. [PMID: 27364121 PMCID: PMC5034851 DOI: 10.1016/j.tim.2016.06.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/31/2016] [Accepted: 06/08/2016] [Indexed: 12/23/2022]
Abstract
Bacterial processes, such as stress responses and cell differentiation, are controlled at many different levels. While some factors, such as transcriptional regulation, are well appreciated, the importance of chromosomal gene location is often underestimated or even completely neglected. A combination of environmental parameters and the chromosomal location of a gene determine how many copies of its DNA are present at a given time during the cell cycle. Here, we review bacterial processes that rely, completely or partially, on the chromosomal location of involved genes and their fluctuating copy numbers. Special attention will be given to the several different ways in which these copy-number fluctuations can be used for bacterial cell fate determination or coordination of interdependent processes in a bacterial cell.
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Affiliation(s)
- Jelle Slager
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Jan-Willem Veening
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
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26
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Abstract
DNA does not make phenotypes on its own. In this volume entitled "Genes and Phenotypic Evolution," the present review draws the attention on the process of phenotype construction-including development of multicellular organisms-and the multiple interactions and feedbacks between DNA, organism, and environment at various levels and timescales in the evolutionary process. First, during the construction of an individual's phenotype, DNA is recruited as a template for building blocks within the cellular context and may in addition be involved in dynamical feedback loops that depend on the environmental and organismal context. Second, in the production of phenotypic variation among individuals, stochastic, environmental, genetic, and parental sources of variation act jointly. While in controlled laboratory settings, various genetic and environmental factors can be tested one at a time or in various combinations, they cannot be separated in natural populations because the environment is not controlled and the genotype can rarely be replicated. Third, along generations, genotype and environment each have specific properties concerning the origin of their variation, the hereditary transmission of this variation, and the evolutionary feedbacks. Natural selection acts as a feedback from phenotype and environment to genotype. This review integrates recent results and concrete examples that illustrate these three points. Although some themes are shared with recent calls and claims to a new conceptual framework in evolutionary biology, the viewpoint presented here only means to add flesh to the standard evolutionary synthesis.
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Affiliation(s)
- M-A Félix
- Institut de Biologie Ecole Normale Supérieure, CNRS, Paris, France.
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27
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Wang LZ, Wu F, Flores K, Lai YC, Wang X. Build to understand: synthetic approaches to biology. Integr Biol (Camb) 2016; 8:394-408. [PMID: 26686885 PMCID: PMC4837018 DOI: 10.1039/c5ib00252d] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this review we discuss how synthetic biology facilitates the task of investigating genetic circuits that are observed in naturally occurring biological systems. Specifically, we give examples where experimentation with synthetic gene circuits has been used to understand four fundamental mechanisms intrinsic to development and disease: multistability, stochastic gene expression, oscillations, and cell-cell communication. Within each area, we also discuss how mathematical modeling has been employed as an essential tool to guide the design of novel gene circuits and as a theoretical basis for exploring circuit topologies exhibiting robust behaviors in the presence of noise.
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Affiliation(s)
- Le-Zhi Wang
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA
| | - Fuqing Wu
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, USA.
| | - Kevin Flores
- Department of Mathematics, Center for Quantitative Sciences in Biomedicine, Center for Research in Scientific Computation, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Ying-Cheng Lai
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA
- Institute for Complex Systems and Mathematical Biology, King’s College, University of Aberdeen, Aberdeen AB24 3UE, UK
- Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
| | - Xiao Wang
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, USA.
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28
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Mestek Boukhibar L, Barkoulas M. The developmental genetics of biological robustness. ANNALS OF BOTANY 2016; 117:699-707. [PMID: 26292993 PMCID: PMC4845795 DOI: 10.1093/aob/mcv128] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/07/2015] [Accepted: 06/29/2015] [Indexed: 05/10/2023]
Abstract
BACKGROUND Living organisms are continuously confronted with perturbations, such as environmental changes that include fluctuations in temperature and nutrient availability, or genetic changes such as mutations. While some developmental systems are affected by such challenges and display variation in phenotypic traits, others continue consistently to produce invariable phenotypes despite perturbation. This ability of a living system to maintain an invariable phenotype in the face of perturbations is termed developmental robustness. Biological robustness is a phenomenon observed across phyla, and studying its mechanisms is central to deciphering the genotype-phenotype relationship. Recent work in yeast, animals and plants has shown that robustness is genetically controlled and has started to reveal the underlying mechinisms behind it. SCOPE AND CONCLUSIONS Studying biological robustness involves focusing on an important property of developmental traits, which is the phenotypic distribution within a population. This is often neglected because the vast majority of developmental biology studies instead focus on population aggregates, such as trait averages. By drawing on findings in animals and yeast, this Viewpoint considers how studies on plant developmental robustness may benefit from strict definitions of what is the developmental system of choice and what is the relevant perturbation, and also from clear distinctions between gene effects on the trait mean and the trait variance. Recent advances in quantitative developmental biology and high-throughput phenotyping now allow the design of targeted genetic screens to identify genes that amplify or restrict developmental trait variance and to study how variation propagates across different phenotypic levels in biological systems. The molecular characterization of more quantitative trait loci affecting trait variance will provide further insights into the evolution of genes modulating developmental robustness. The study of robustness mechanisms in closely related species will address whether mechanisms of robustness are evolutionarily conserved.
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Affiliation(s)
- Lamia Mestek Boukhibar
- Imperial College London, Department of Life Sciences, Sir Alexander Fleming Building, South Kensington Campus, London SW7 2AZ, UK
| | - Michalis Barkoulas
- Imperial College London, Department of Life Sciences, Sir Alexander Fleming Building, South Kensington Campus, London SW7 2AZ, UK
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Noise propagation with interlinked feed-forward pathways. Sci Rep 2016; 6:23607. [PMID: 27029397 PMCID: PMC4814832 DOI: 10.1038/srep23607] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 03/10/2016] [Indexed: 12/05/2022] Open
Abstract
Functionally similar pathways are often seen in biological systems, forming feed-forward controls. The robustness in network motifs such as feed-forward loops (FFLs) has been reported previously. In this work, we studied noise propagation in a development network that has multiple interlinked FFLs. A FFL has the potential of asymmetric noise-filtering (i.e., it works at either the “ON” or the “OFF” state in the target gene). With multiple, interlinked FFLs, we show that the propagated noises are largely filtered regardless of the states in the input genes. The noise-filtering property of an interlinked FFL can be largely derived from that of the individual FFLs, and with interlinked FFLs, it is possible to filter noises in both “ON” and “OFF” states in the output. We demonstrated the noise filtering effect in the developmental regulatory network of Caenorhabditis elegans that controls the timing of distal tip cell (DTC) migration. The roles of positive feedback loops involving blmp-1 and the degradation regulation of DRE-1 also studied. Our analyses allow for better inference from network structures to noise-filtering properties, and provide insights into the mechanisms behind the precise DTC migration controls in space and time.
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Abstract
Endospore formation follows a complex, highly regulated developmental pathway that occurs in a broad range of Firmicutes. Although Bacillus subtilis has served as a powerful model system to study the morphological, biochemical, and genetic determinants of sporulation, fundamental aspects of the program remain mysterious for other genera. For example, it is entirely unknown how most lineages within the Firmicutes regulate entry into sporulation. Additionally, little is known about how the sporulation pathway has evolved novel spore forms and reproductive schemes. Here, we describe endospore and internal offspring development in diverse Firmicutes and outline progress in characterizing these programs. Moreover, comparative genomics studies are identifying highly conserved sporulation genes, and predictions of sporulation potential in new isolates and uncultured bacteria can be made from these data. One surprising outcome of these comparative studies is that core regulatory and some structural aspects of the program appear to be universally conserved. This suggests that a robust and sophisticated developmental framework was already in place in the last common ancestor of all extant Firmicutes that produce internal offspring or endospores. The study of sporulation in model systems beyond B. subtilis will continue to provide key information on the flexibility of the program and provide insights into how changes in this developmental course may confer advantages to cells in diverse environments.
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Cassona CP, Pereira F, Serrano M, Henriques AO. A Fluorescent Reporter for Single Cell Analysis of Gene Expression in Clostridium difficile. Methods Mol Biol 2016; 1476:69-90. [PMID: 27507334 DOI: 10.1007/978-1-4939-6361-4_6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Genetically identical cells growing under homogeneous growth conditions often display cell-cell variation in gene expression. This variation stems from noise in gene expression and can be adaptive allowing for division of labor and bet-hedging strategies. In particular, for bacterial pathogens, the expression of phenotypes related to virulence can show cell-cell variation. Therefore, understanding virulence-related gene expression requires knowledge of gene expression patterns at the single cell level. We describe protocols for the use of fluorescence reporters for single cell analysis of gene expression in the human enteric pathogen Clostridium difficile, a strict anaerobe. The reporters are based on modified versions of the human DNA repair enzyme O ( 6)-alkylguanine-DNA alkyltransferase, called SNAP-tag and CLIP-tag. SNAP becomes covalently labeled upon reaction with O ( 6)-benzylguanine conjugated to a fluorophore, whereas CLIP is labeled by O ( 6)-benzylcytosine conjugates. SNAP and CLIP labeling is orthogonal allowing for dual labeling in the same cells. SNAP and CLIP cassettes optimized for C. difficile can be used for quantitative studies of gene expression at the single cell level. Both the SNAP and CLIP reporters can also be used for studies of protein subcellular localization in C. difficile.
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Affiliation(s)
- Carolina Piçarra Cassona
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, 2780-157, Oeiras, Portugal
| | - Fátima Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, 2780-157, Oeiras, Portugal
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Althanstr. 14, 1090, Vienna, Austria
| | - Mónica Serrano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, 2780-157, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, 2780-157, Oeiras, Portugal.
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Fish JL. Developmental mechanisms underlying variation in craniofacial disease and evolution. Dev Biol 2015; 415:188-197. [PMID: 26724698 DOI: 10.1016/j.ydbio.2015.12.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 12/17/2015] [Accepted: 12/21/2015] [Indexed: 01/14/2023]
Abstract
Craniofacial disease phenotypes exhibit significant variation in penetrance and severity. Although many genetic contributions to phenotypic variation have been identified, genotype-phenotype correlations remain imprecise. Recent work in evolutionary developmental biology has exposed intriguing developmental mechanisms that potentially explain incongruities in genotype-phenotype relationships. This review focuses on two observations from work in comparative and experimental animal model systems that highlight how development structures variation. First, multiple genetic inputs converge on relatively few developmental processes. Investigation of when and how variation in developmental processes occurs may therefore help predict potential genetic interactions and phenotypic outcomes. Second, genetic mutation is typically associated with an increase in phenotypic variance. Several models outlining developmental mechanisms underlying mutational increases in phenotypic variance are discussed using Satb2-mediated variation in jaw size as an example. These data highlight development as a critical mediator of genotype-phenotype correlations. Future research in evolutionary developmental biology focusing on tissue-level processes may help elucidate the "black box" between genotype and phenotype, potentially leading to novel treatment, earlier diagnoses, and better clinical consultations for individuals affected by craniofacial anomalies.
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Affiliation(s)
- Jennifer L Fish
- University of Massachusetts Lowell, Department of Biological Sciences, 198 Riverside Street, Olsen Hall, Room 619, Lowell, MA 01854, United States.
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Abstract
Epistatic interactions can frustrate and shape evolutionary change. Indeed, phenotypes may fail to evolve when essential mutations are only accessible through positive selection if they are fixed simultaneously. How environmental variability affects such constraints is poorly understood. Here, we studied genetic constraints in fixed and fluctuating environments using the Escherichia coli lac operon as a model system for genotype-environment interactions. We found that, in different fixed environments, all trajectories that were reconstructed by applying point mutations within the transcription factor-operator interface became trapped at suboptima, where no additional improvements were possible. Paradoxically, repeated switching between these same environments allows unconstrained adaptation by continuous improvements. This evolutionary mode is explained by pervasive cross-environmental tradeoffs that reposition the peaks in such a way that trapped genotypes can repeatedly climb ascending slopes and hence, escape adaptive stasis. Using a Markov approach, we developed a mathematical framework to quantify the landscape-crossing rates and show that this ratchet-like adaptive mechanism is robust in a wide spectrum of fluctuating environments. Overall, this study shows that genetic constraints can be overcome by environmental change and that cross-environmental tradeoffs do not necessarily impede but also, can facilitate adaptive evolution. Because tradeoffs and environmental variability are ubiquitous in nature, we speculate this evolutionary mode to be of general relevance.
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35
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Morange M. Synthetic Biology: A Bridge Between Functional and Evolutionary Biology. ACTA ACUST UNITED AC 2015. [DOI: 10.1162/biot_a_00003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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36
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Berkov-Zrihen Y, Herzog IM, Benhamou RI, Feldman M, Steinbuch KB, Shaul P, Lerer S, Eldar A, Fridman M. Tobramycin and Nebramine as Pseudo-oligosaccharide Scaffolds for the Development of Antimicrobial Cationic Amphiphiles. Chemistry 2015; 21:4340-9. [DOI: 10.1002/chem.201406404] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Indexed: 12/31/2022]
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Bauer CR, Li S, Siegal ML. Essential gene disruptions reveal complex relationships between phenotypic robustness, pleiotropy, and fitness. Mol Syst Biol 2015; 11:773. [PMID: 25609648 PMCID: PMC4332149 DOI: 10.15252/msb.20145264] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The concept of robustness in biology has gained much attention recently, but a mechanistic understanding of how genetic networks regulate phenotypic variation has remained elusive. One approach to understand the genetic architecture of variability has been to analyze dispensable gene deletions in model organisms; however, the most important genes cannot be deleted. Here, we have utilized two systems in yeast whereby essential genes have been altered to reduce expression. Using high-throughput microscopy and image analysis, we have characterized a large number of morphological phenotypes, and their associated variation, for the majority of essential genes in yeast. Our results indicate that phenotypic robustness is more highly dependent upon the expression of essential genes than on the presence of dispensable genes. Morphological robustness appears to be a general property of a genotype that is closely related to pleiotropy. While the fitness profile across a range of expression levels is idiosyncratic to each gene, the global pattern indicates that there is a window in which phenotypic variation can be released before fitness effects are observable.
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Affiliation(s)
- Christopher R Bauer
- Department of Biology, NYU Center for Genomics and Systems Biology, New York, NY, USA
| | - Shuang Li
- Department of Biology, NYU Center for Genomics and Systems Biology, New York, NY, USA
| | - Mark L Siegal
- Department of Biology, NYU Center for Genomics and Systems Biology, New York, NY, USA
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Dhar N, Manina G. Single-cell analysis of mycobacteria using microfluidics and time-lapse microscopy. Methods Mol Biol 2015; 1285:241-256. [PMID: 25779320 DOI: 10.1007/978-1-4939-2450-9_14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The crucial role of phenotypic heterogeneity in bacterial physiology and adaptive responses has required the introduction of new ways to investigate bacterial individuality. Time-lapse microscopy is a powerful technique for evaluating phenotypic diversity in bacteria at the single-cell level, whether exploring the dynamics of gene expression and protein localization or characterizing the heterogeneous phenotypic response to perturbations. Here, we present protocols to carry out time-lapse imaging of mycobacteria at the single-cell level using either agarose pads or customized microfluidic devices. The sequences of images obtained can be analyzed using programs such as ImageJ and allow the investigator not only to extract various parameters of growth and gene expression dynamics but also to unravel the physiological basis behind phenomenon such as persistence against stresses.
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Affiliation(s)
- Neeraj Dhar
- Laboratory of Microbiology and Microsystems, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Station 19, Office SV 3832, Lausanne, CH-1015, Switzerland,
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The RapP-PhrP quorum-sensing system of Bacillus subtilis strain NCIB3610 affects biofilm formation through multiple targets, due to an atypical signal-insensitive allele of RapP. J Bacteriol 2014; 197:592-602. [PMID: 25422306 DOI: 10.1128/jb.02382-14] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The genome of Bacillus subtilis 168 encodes eight rap-phr quorum-sensing pairs. Rap proteins of all characterized Rap-Phr pairs inhibit the function of one or several important response regulators: ComA, Spo0F, or DegU. This inhibition is relieved upon binding of the peptide encoded by the cognate phr gene. Bacillus subtilis strain NCIB3610, the biofilm-proficient ancestor of strain 168, encodes, in addition, the rapP-phrP pair on the plasmid pBS32. RapP was shown to dephosphorylate Spo0F and to regulate biofilm formation, but unlike other Rap-Phr pairs, RapP does not interact with PhrP. In this work we extend the analysis of the RapP pathway by reexamining its transcriptional regulation, its effect on downstream targets, and its interaction with PhrP. At the transcriptional level, we show that rapP and phrP regulation is similar to that of other rap-phr pairs. We further find that RapP has an Spo0F-independent negative effect on biofilm-related genes, which is mediated by the response regulator ComA. Finally, we find that the insensitivity of RapP to PhrP is due to a substitution of a highly conserved residue in the peptide binding domain of the rapP allele of strain NCIB3610. Reversing this substitution to the consensus amino acid restores the PhrP dependence of RapP activity and eliminates the effects of the rapP-phrP locus on ComA activity and biofilm formation. Taken together, our results suggest that RapP strongly represses biofilm formation through multiple targets and that PhrP does not counteract RapP due to a rare mutation in rapP.
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40
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Transcriptome-wide variability in single embryonic development cells. Sci Rep 2014; 4:7137. [PMID: 25409746 PMCID: PMC4238013 DOI: 10.1038/srep07137] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 11/04/2014] [Indexed: 11/23/2022] Open
Abstract
Molecular heterogeneity of individual molecules within single cells has been recently shown to be crucial for cell fate diversifications. However, on a global scale, the effect of molecular variability for embryonic developmental stages is largely underexplored. Here, to understand the origins of transcriptome-wide variability of oocytes to blastocysts in human and mouse, we examined RNA-Seq datasets. Evaluating Pearson correlation, Shannon entropy and noise patterns (η2vs.μ), our investigations reveal a phase transition from low to saturating levels of diversity and variability of transcriptome-wide expressions through the development stages. To probe the observed behaviour further, we utilised a stochastic transcriptional model to simulate the global gene expressions pattern for each development stage. From the model, we concur that transcriptome-wide regulation initially begins from 2-cell stage, and becomes strikingly variable from 8-cell stage due to amplification and quantal transcriptional activity.
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41
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Abstract
Part of molecular and phenotypic differences between individual cells, between body parts, or between individuals can result from biological noise. This source of variation is becoming more and more apparent thanks to the recent advances in dynamic imaging and single-cell analysis. Some of these studies showed that the link between genotype and phenotype is not strictly deterministic. Mutations can change various statistical properties of a biochemical reaction, and thereby the probability of a trait outcome. The fact that they can modulate phenotypic noise brings up an intriguing question: how may selection act on these mutations? In this review, we approach this question by first covering the evidence that biological noise is under genetic control and therefore a substrate for evolution. We then sequentially inspect the possibilities of negative, neutral, and positive selection for mutations increasing biological noise. Finally, we hypothesize on the specific case of H2A.Z, which was shown to both buffer phenotypic noise and modulate transcriptional efficiency.
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Affiliation(s)
- Magali Richard
- Laboratoire de Biologie Moléculaire de la Cellule, Ecole Normale Supérieure de Lyon, Centre National de la Recherche Scientifique - Université de Lyon Lyon, France
| | - Gaël Yvert
- Laboratoire de Biologie Moléculaire de la Cellule, Ecole Normale Supérieure de Lyon, Centre National de la Recherche Scientifique - Université de Lyon Lyon, France
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Antibiotic-induced replication stress triggers bacterial competence by increasing gene dosage near the origin. Cell 2014; 157:395-406. [PMID: 24725406 DOI: 10.1016/j.cell.2014.01.068] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 12/01/2013] [Accepted: 01/29/2014] [Indexed: 12/12/2022]
Abstract
Streptococcus pneumoniae (pneumococcus) kills nearly 1 million children annually, and the emergence of antibiotic-resistant strains poses a serious threat to human health. Because pneumococci can take up DNA from their environment by a process called competence, genes associated with antibiotic resistance can rapidly spread. Remarkably, competence is activated in response to several antibiotics. Here, we demonstrate that antibiotics targeting DNA replication cause an increase in the copy number of genes proximal to the origin of replication (oriC). As the genes required for competence initiation are located near oriC, competence is thereby activated. Transcriptome analyses show that antibiotics targeting DNA replication also upregulate origin-proximal gene expression in other bacteria. This mechanism is a direct, intrinsic consequence of replication fork stalling. Our data suggest that evolution has conserved the oriC-proximal location of important genes in bacteria to allow for a robust response to replication stress without the need for complex gene-regulatory pathways. PAPERCLIP:
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Kar RK, Qureshi MT, DasAdhikari AK, Zahir T, Venkatesh KV, Bhat PJ. Stochastic galactokinase expression underlies GAL gene induction in a GAL3 mutant of Saccharomyces cerevisiae. FEBS J 2014; 281:1798-817. [PMID: 24785355 DOI: 10.1111/febs.12741] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
GAL1 and GAL3 are paralogous signal transducers that functionally inactivate Gal80p to activate the Gal4p-dependent transcriptional activation of GAL genes in Saccharomyces cerevisiae in response to galactose. Unlike a wild-type strain, the gal3∆ strain shows delayed growth kinetics as a result of the signaling function of GAL1. The mechanism ensuring that GAL1 is eventually expressed to turn on the GAL switch in the gal3∆ strain remains a paradox. Using galactose and histidine growth complementation assays, we demonstrate that 0.3% of the gal3∆ cell population responds to galactose. This is corroborated by flow cytometry and microscopic analysis. The galactose responders and nonresponders isolated from the galactose-adapted population attain the original bimodal state and this phenotype is found to be as hard wired as a genetic trait. Computational analysis suggests that the log-normal distribution in GAL4 synthesis can lead to bimodal expression of GAL80, resulting in the bimodal expression of GAL genes. Heterozygosity at the GAL80 but not at the GAL1, GAL2 or GAL4 locus alters the extent of bimodality of the gal3∆ cell population. We suggest that the asymmetric expression pattern between GAL1 and GAL3 results in the ability of S. cerevisiae to activate the GAL pathway by conferring nongenetic heterogeneity.
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Affiliation(s)
- Rajesh Kumar Kar
- Molecular Genetics Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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44
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Leier A, Barrio M, Marquez-Lago TT. Exact model reduction with delays: closed-form distributions and extensions to fully bi-directional monomolecular reactions. J R Soc Interface 2014; 11:20140108. [PMID: 24694895 PMCID: PMC4006250 DOI: 10.1098/rsif.2014.0108] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In order to systematically understand the qualitative and quantitative behaviour of chemical reaction networks, scientists must derive and analyse associated mathematical models. However, biochemical systems are often very large, with reactions occurring at multiple time scales, as evidenced by signalling pathways and gene expression kinetics. Owing to the associated computational costs, it is then many times impractical, if not impossible, to solve or simulate these systems with an appropriate level of detail. By consequence, there is a growing interest in developing techniques for the simplification or reduction of complex biochemical systems. Here, we extend our recently presented methodology on exact reduction of linear chains of reactions with delay distributions in two ways. First, we report that it is now possible to deal with fully bi-directional monomolecular systems, including degradations, synthesis and generalized bypass reactions. Second, we provide all derivations of associated delays in analytical, closed form. Both advances have a major impact on further reducing computational costs, while still retaining full accuracy. Thus, we expect our new methodology to respond to current simulation needs in pharmaceutical, chemical and biological research.
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Affiliation(s)
- Andre Leier
- Okinawa Institute of Science and Technology, , Okinawa, Japan
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45
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Farkash-Amar S, Zimmer A, Eden E, Cohen A, Geva-Zatorsky N, Cohen L, Milo R, Sigal A, Danon T, Alon U. Noise genetics: inferring protein function by correlating phenotype with protein levels and localization in individual human cells. PLoS Genet 2014; 10:e1004176. [PMID: 24603725 PMCID: PMC3945223 DOI: 10.1371/journal.pgen.1004176] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 12/30/2013] [Indexed: 02/03/2023] Open
Abstract
To understand gene function, genetic analysis uses large perturbations such as gene deletion, knockdown or over-expression. Large perturbations have drawbacks: they move the cell far from its normal working point, and can thus be masked by off-target effects or compensation by other genes. Here, we offer a complementary approach, called noise genetics. We use natural cell-cell variations in protein level and localization, and correlate them to the natural variations of the phenotype of the same cells. Observing these variations is made possible by recent advances in dynamic proteomics that allow measuring proteins over time in individual living cells. Using motility of human cancer cells as a model system, and time-lapse microscopy on 566 fluorescently tagged proteins, we found 74 candidate motility genes whose level or localization strongly correlate with motility in individual cells. We recovered 30 known motility genes, and validated several novel ones by mild knockdown experiments. Noise genetics can complement standard genetics for a variety of phenotypes.
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Affiliation(s)
- Shlomit Farkash-Amar
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Anat Zimmer
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Eran Eden
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Ariel Cohen
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Geva-Zatorsky
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Lydia Cohen
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Ron Milo
- Department of Plant Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Alex Sigal
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Danon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Uri Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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46
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Schlichting CD, Wund MA. Phenotypic plasticity and epigenetic marking: an assessment of evidence for genetic accommodation. Evolution 2014; 68:656-72. [PMID: 24410266 DOI: 10.1111/evo.12348] [Citation(s) in RCA: 183] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 12/22/2013] [Indexed: 12/16/2022]
Abstract
The relationship between genotype (which is inherited) and phenotype (the target of selection) is mediated by environmental inputs on gene expression, trait development, and phenotypic integration. Phenotypic plasticity or epigenetic modification might influence evolution in two general ways: (1) by stimulating evolutionary responses to environmental change via population persistence or by revealing cryptic genetic variation to selection, and (2) through the process of genetic accommodation, whereby natural selection acts to improve the form, regulation, and phenotypic integration of novel phenotypic variants. We provide an overview of models and mechanisms for how such evolutionary influences may be manifested both for plasticity and epigenetic marking. We point to promising avenues of research, identifying systems that can best be used to address the role of plasticity in evolution, as well as the need to apply our expanding knowledge of genetic and epigenetic mechanisms to our understanding of how genetic accommodation occurs in nature. Our review of a wide variety of studies finds widespread evidence for evolution by genetic accommodation.
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Affiliation(s)
- Carl D Schlichting
- Department of Ecology & Evolutionary Biology, U-3043, University of Connecticut, Storrs, Connecticut 06269.
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47
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Ji N, Middelkoop TC, Mentink RA, Betist MC, Tonegawa S, Mooijman D, Korswagen HC, van Oudenaarden A. Feedback control of gene expression variability in the Caenorhabditis elegans Wnt pathway. Cell 2014; 155:869-80. [PMID: 24209624 DOI: 10.1016/j.cell.2013.09.060] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 07/26/2013] [Accepted: 09/27/2013] [Indexed: 12/13/2022]
Abstract
Variability in gene expression contributes to phenotypic heterogeneity even in isogenic populations. Here, we used the stereotyped, Wnt signaling-dependent development of the Caenorhabditis elegans Q neuroblast to probe endogenous mechanisms that control gene expression variability. We found that the key Hox gene that orients Q neuroblast migration exhibits increased gene expression variability in mutants in which Wnt pathway activity has been perturbed. Distinct features of the gene expression distributions prompted us on a systematic search for regulatory interactions, revealing a network of interlocked positive and negative feedback loops. Interestingly, positive feedback appeared to cooperate with negative feedback to reduce variability while keeping the Hox gene expression at elevated levels. A minimal model correctly predicts the increased gene expression variability across mutants. Our results highlight the influence of gene network architecture on expression variability and implicate feedback regulation as an effective mechanism to ensure developmental robustness.
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Affiliation(s)
- Ni Ji
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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Konovalova A, Søgaard-Andersen L, Kroos L. Regulated proteolysis in bacterial development. FEMS Microbiol Rev 2013; 38:493-522. [PMID: 24354618 DOI: 10.1111/1574-6976.12050] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/03/2013] [Accepted: 10/14/2013] [Indexed: 11/30/2022] Open
Abstract
Bacteria use proteases to control three types of events temporally and spatially during the processes of morphological development. These events are the destruction of regulatory proteins, activation of regulatory proteins, and production of signals. While some of these events are entirely cytoplasmic, others involve intramembrane proteolysis of a substrate, transmembrane signaling, or secretion. In some cases, multiple proteolytic events are organized into pathways, for example turnover of a regulatory protein activates a protease that generates a signal. We review well-studied and emerging examples and identify recurring themes and important questions for future research. We focus primarily on paradigms learned from studies of model organisms, but we note connections to regulated proteolytic events that govern bacterial adaptation, biofilm formation and disassembly, and pathogenesis.
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Affiliation(s)
- Anna Konovalova
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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Pereira FC, Saujet L, Tomé AR, Serrano M, Monot M, Couture-Tosi E, Martin-Verstraete I, Dupuy B, Henriques AO. The spore differentiation pathway in the enteric pathogen Clostridium difficile. PLoS Genet 2013; 9:e1003782. [PMID: 24098139 PMCID: PMC3789829 DOI: 10.1371/journal.pgen.1003782] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 07/25/2013] [Indexed: 12/20/2022] Open
Abstract
Endosporulation is an ancient bacterial developmental program that culminates with the differentiation of a highly resistant endospore. In the model organism Bacillus subtilis, gene expression in the forespore and in the mother cell, the two cells that participate in endospore development, is governed by cell type-specific RNA polymerase sigma subunits. σ(F) in the forespore, and σ(E) in the mother cell control early stages of development and are replaced, at later stages, by σ(G) and σ(K), respectively. Starting with σ(F), the activation of the sigma factors is sequential, requires the preceding factor, and involves cell-cell signaling pathways that operate at key morphological stages. Here, we have studied the function and regulation of the sporulation sigma factors in the intestinal pathogen Clostridium difficile, an obligate anaerobe in which the endospores are central to the infectious cycle. The morphological characterization of mutants for the sporulation sigma factors, in parallel with use of a fluorescence reporter for single cell analysis of gene expression, unraveled important deviations from the B. subtilis paradigm. While the main periods of activity of the sigma factors are conserved, we show that the activity of σ(E) is partially independent of σ(F), that σ(G) activity is not dependent on σ(E), and that the activity of σ(K) does not require σ(G). We also show that σ(K) is not strictly required for heat resistant spore formation. In all, our results indicate reduced temporal segregation between the activities of the early and late sigma factors, and reduced requirement for the σ(F)-to-σ(E), σ(E)-to-σ(G), and σ(G)-to-σ(K) cell-cell signaling pathways. Nevertheless, our results support the view that the top level of the endosporulation network is conserved in evolution, with the sigma factors acting as the key regulators of the pathway, established some 2.5 billion years ago upon its emergence at the base of the Firmicutes Phylum.
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Affiliation(s)
- Fátima C. Pereira
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, ITQB-UNL, Estação Agronómica Nacional, Oeiras, Portugal
| | - Laure Saujet
- Univ. Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
| | - Ana R. Tomé
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, ITQB-UNL, Estação Agronómica Nacional, Oeiras, Portugal
| | - Mónica Serrano
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, ITQB-UNL, Estação Agronómica Nacional, Oeiras, Portugal
| | - Marc Monot
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
| | - Evelyne Couture-Tosi
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
| | - Isabelle Martin-Verstraete
- Univ. Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
| | - Bruno Dupuy
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
- * E-mail: (BD); (AOH)
| | - Adriano O. Henriques
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, ITQB-UNL, Estação Agronómica Nacional, Oeiras, Portugal
- * E-mail: (BD); (AOH)
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Saujet L, Pereira FC, Serrano M, Soutourina O, Monot M, Shelyakin PV, Gelfand MS, Dupuy B, Henriques AO, Martin-Verstraete I. Genome-wide analysis of cell type-specific gene transcription during spore formation in Clostridium difficile. PLoS Genet 2013; 9:e1003756. [PMID: 24098137 PMCID: PMC3789822 DOI: 10.1371/journal.pgen.1003756] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 07/12/2013] [Indexed: 01/05/2023] Open
Abstract
Clostridium difficile, a Gram positive, anaerobic, spore-forming bacterium is an emergent pathogen and the most common cause of nosocomial diarrhea. Although transmission of C. difficile is mediated by contamination of the gut by spores, the regulatory cascade controlling spore formation remains poorly characterized. During Bacillus subtilis sporulation, a cascade of four sigma factors, σ(F) and σ(G) in the forespore and σ(E) and σ(K) in the mother cell governs compartment-specific gene expression. In this work, we combined genome wide transcriptional analyses and promoter mapping to define the C. difficile σ(F), σ(E), σ(G) and σ(K) regulons. We identified about 225 genes under the control of these sigma factors: 25 in the σ(F) regulon, 97 σ(E)-dependent genes, 50 σ(G)-governed genes and 56 genes under σ(K) control. A significant fraction of genes in each regulon is of unknown function but new candidates for spore coat proteins could be proposed as being synthesized under σ(E) or σ(K) control and detected in a previously published spore proteome. SpoIIID of C. difficile also plays a pivotal role in the mother cell line of expression repressing the transcription of many members of the σ(E) regulon and activating sigK expression. Global analysis of developmental gene expression under the control of these sigma factors revealed deviations from the B. subtilis model regarding the communication between mother cell and forespore in C. difficile. We showed that the expression of the σ(E) regulon in the mother cell was not strictly under the control of σ(F) despite the fact that the forespore product SpoIIR was required for the processing of pro-σ(E). In addition, the σ(K) regulon was not controlled by σ(G) in C. difficile in agreement with the lack of pro-σ(K) processing. This work is one key step to obtain new insights about the diversity and evolution of the sporulation process among Firmicutes.
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Affiliation(s)
- Laure Saujet
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
| | - Fátima C. Pereira
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Monica Serrano
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Olga Soutourina
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
| | - Marc Monot
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
| | - Pavel V. Shelyakin
- Institute for Information Transmission Problems, RAS, Bolshoi Karetny per, 19, Moscow, Russia
| | - Mikhail S. Gelfand
- Institute for Information Transmission Problems, RAS, Bolshoi Karetny per, 19, Moscow, Russia
- M.V. Lomonosov Moscow State University, Faculty of Biengineering and Bioinformatics, Vorobievy Gory 1-73, Moscow, Russia
| | - Bruno Dupuy
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
| | - Adriano O. Henriques
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Isabelle Martin-Verstraete
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
- * E-mail:
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