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  1. AU="Moolman, M Charl"
  2. AU="Mazzoni, Stefania"
  3. AU=Stryjewski Martin E
  4. AU=Vallon Volker AU=Vallon Volker
  5. AU="Knowland, K E"
  6. AU="Beker, M. G."

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  1. Artikel ; Online: Quantitative Analysis of Intracellular Fluorescent Foci in Live Bacteria.

    Moolman, M Charl / Kerssemakers, Jacob W J / Dekker, Nynke H

    Biophysical journal

    2015  Band 109, Heft 5, Seite(n) 883–891

    Abstract: Fluorescence microscopy has revolutionized in vivo cellular biology. Through the specific labeling of a protein of interest with a fluorescent protein, one is able to study movement and colocalization, and even count individual proteins in a live cell. ... ...

    Abstract Fluorescence microscopy has revolutionized in vivo cellular biology. Through the specific labeling of a protein of interest with a fluorescent protein, one is able to study movement and colocalization, and even count individual proteins in a live cell. Different algorithms exist to quantify the total intensity and position of a fluorescent focus. Although these algorithms have been rigorously studied for in vitro conditions, which are greatly different than the in-homogenous and variable cellular environments, their exact limits and applicability in the context of a live cell have not been thoroughly and systematically evaluated. In this study, we quantitatively characterize the influence of different background subtraction algorithms on several focus analysis algorithms. We use, to our knowledge, a novel approach to assess the sensitivity of the focus analysis algorithms to background removal, in which simulated and experimental data are combined to maintain full control over the sensitivity of a focus within a realistic background of cellular fluorescence. We demonstrate that the choice of algorithm and the corresponding error are dependent on both the brightness of the focus, and the cellular context. Expectedly, focus intensity estimation and localization accuracy suffer in all algorithms at low focus to background ratios, with the bacteroidal background subtraction in combination with the median excess algorithm, and the region of interest background subtraction in combination with a two-dimensional Gaussian fit algorithm, performing the best. We furthermore show that the choice of background subtraction algorithm is dependent on the expression level of the protein under investigation, and that the localization error is dependent on the distance of a focus from the bacterial edge and pole. Our results establish a set of guidelines for what signals can be analyzed to give a targeted spatial and intensity accuracy within a bacterial cell.
    Mesh-Begriff(e) Escherichia coli K12/cytology ; Intracellular Space/metabolism ; Microscopy, Fluorescence
    Sprache Englisch
    Erscheinungsdatum 2015-09-01
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 218078-9
    ISSN 1542-0086 ; 0006-3495
    ISSN (online) 1542-0086
    ISSN 0006-3495
    DOI 10.1016/j.bpj.2015.07.013
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  2. Artikel: Essential validation methods for E. coli strains created by chromosome engineering.

    Tiruvadi Krishnan, Sriram / Moolman, M Charl / van Laar, Theo / Meyer, Anne S / Dekker, Nynke H

    Journal of biological engineering

    2015  Band 9, Seite(n) 11

    Abstract: Background: Chromosome engineering encompasses a collection of homologous recombination-based techniques that are employed to modify the genome of a model organism in a controlled fashion. Such techniques are widely used in both fundamental and ... ...

    Abstract Background: Chromosome engineering encompasses a collection of homologous recombination-based techniques that are employed to modify the genome of a model organism in a controlled fashion. Such techniques are widely used in both fundamental and industrial research to introduce multiple insertions in the same Escherichia coli strain. To date, λ-Red recombination (also known as recombineering) and P1 phage transduction are the most successfully implemented chromosome engineering techniques in E. coli. However, due to errors that can occur during the strain creation process, reliable validation methods are essential upon alteration of a strain's chromosome.
    Results and discussion: Polymerase chain reaction (PCR)-based methods and DNA sequence analysis are rapid and powerful methods to verify successful integration of DNA sequences into a chromosome. Even though these verification methods are necessary, they may not be sufficient in detecting all errors, imposing the requirement of additional validation methods. For example, as extraneous insertions may occur during recombineering, we highlight the use of Southern blotting to detect their presence. These unwanted mutations can be removed via transducing the region of interest into the wild type chromosome using P1 phages. However, in doing so one must verify that both the P1 lysate and the strains utilized are free from contamination with temperate phages, as these can lysogenize inside a cell as a large plasmid. Thus, we illustrate various methods to probe for temperate phage contamination, including cross-streak agar and Evans Blue-Uranine (EBU) plate assays, whereby the latter is a newly reported technique for this purpose in E. coli. Lastly, we discuss methodologies for detecting defects in cell growth and shape characteristics, which should be employed as an additional check.
    Conclusion: The simple, yet crucial validation techniques discussed here can be used to reliably verify any chromosomally engineered E. coli strains for errors such as non-specific insertions in the chromosome, temperate phage contamination, and defects in growth and cell shape. While techniques such as PCR and DNA sequence verification should standardly be performed, we illustrate the necessity of performing these additional assays. The discussed techniques are highly generic and can be easily applied to any type of chromosome engineering.
    Sprache Englisch
    Erscheinungsdatum 2015-07-01
    Erscheinungsland England
    Dokumenttyp Journal Article
    ZDB-ID 2391582-1
    ISSN 1754-1611
    ISSN 1754-1611
    DOI 10.1186/s13036-015-0008-x
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  3. Artikel ; Online: Stochasticity and homeostasis in the E. coli replication and division cycle.

    Adiciptaningrum, Aileen / Osella, Matteo / Moolman, M Charl / Cosentino Lagomarsino, Marco / Tans, Sander J

    Scientific reports

    2015  Band 5, Seite(n) 18261

    Abstract: How cells correct for stochasticity to coordinate the chromosome replication and cellular division cycle is poorly understood. We used time-lapse microscopy and fluorescently labelled SeqA to determine the timing of birth, initiation, termination, and ... ...

    Abstract How cells correct for stochasticity to coordinate the chromosome replication and cellular division cycle is poorly understood. We used time-lapse microscopy and fluorescently labelled SeqA to determine the timing of birth, initiation, termination, and division, as well as cell size throughout the cell cycle. We found that the time between birth and initiation (B-period) compensates for stochastic variability in birth size and growth rate. The time between termination and division (D-period) also compensates for size and growth variability, invalidating the notion that replication initiation is the principal trigger for cell division. In contrast, the time between initiation and termination (C-period) did not display such compensations. Interestingly, the C-period did show small but systematic decreases for cells that spontaneously grew faster, which suggests a coupling between metabolic fluctuations and replication. An auto-regressive theoretical framework was employed to compare different possible models of sub-period control.
    Mesh-Begriff(e) Cell Cycle ; Cell Division ; DNA Replication ; Escherichia coli/physiology ; Homeostasis ; Microbial Viability ; Models, Biological
    Sprache Englisch
    Erscheinungsdatum 2015-12-16
    Erscheinungsland England
    Dokumenttyp Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/srep18261
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  4. Artikel ; Online: Studying genomic processes at the single-molecule level: introducing the tools and applications.

    Dulin, David / Lipfert, Jan / Moolman, M Charl / Dekker, Nynke H

    Nature reviews. Genetics

    2012  Band 14, Heft 1, Seite(n) 9–22

    Abstract: To understand genomic processes such as transcription, translation or splicing, we need to be able to study their spatial and temporal organization at the molecular level. Single-molecule approaches provide this opportunity, allowing researchers to ... ...

    Abstract To understand genomic processes such as transcription, translation or splicing, we need to be able to study their spatial and temporal organization at the molecular level. Single-molecule approaches provide this opportunity, allowing researchers to monitor molecular conformations, interactions or diffusion quantitatively and in real time in purified systems and in the context of the living cell. This Review introduces the types of application of single-molecule approaches that can enhance our understanding of genome function.
    Mesh-Begriff(e) DNA Replication ; Genetic Phenomena ; Genomics/methods ; Genomics/trends ; Protein Biosynthesis ; Transcription, Genetic
    Sprache Englisch
    Erscheinungsdatum 2012-10-30
    Erscheinungsland England
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2035157-4
    ISSN 1471-0064 ; 1471-0056
    ISSN (online) 1471-0064
    ISSN 1471-0056
    DOI 10.1038/nrg3316
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  5. Artikel ; Online: The progression of replication forks at natural replication barriers in live bacteria.

    Moolman, M Charl / Tiruvadi Krishnan, Sriram / Kerssemakers, Jacob W J / de Leeuw, Roy / Lorent, Vincent / Sherratt, David J / Dekker, Nynke H

    Nucleic acids research

    2016  Band 44, Heft 13, Seite(n) 6262–6273

    Abstract: Protein-DNA complexes are one of the principal barriers the replisome encounters during replication. One such barrier is the Tus-ter complex, which is a direction dependent barrier for replication fork progression. The details concerning the dynamics of ... ...

    Abstract Protein-DNA complexes are one of the principal barriers the replisome encounters during replication. One such barrier is the Tus-ter complex, which is a direction dependent barrier for replication fork progression. The details concerning the dynamics of the replisome when encountering these Tus-ter barriers in the cell are poorly understood. By performing quantitative fluorescence microscopy with microfuidics, we investigate the effect on the replisome when encountering these barriers in live Escherichia coli cells. We make use of an E. coli variant that includes only an ectopic origin of replication that is positioned such that one of the two replisomes encounters a Tus-ter barrier before the other replisome. This enables us to single out the effect of encountering a Tus-ter roadblock on an individual replisome. We demonstrate that the replisome remains stably bound after encountering a Tus-ter complex from the non-permissive direction. Furthermore, the replisome is only transiently blocked, and continues replication beyond the barrier. Additionally, we demonstrate that these barriers affect sister chromosome segregation by visualizing specific chromosomal loci in the presence and absence of the Tus protein. These observations demonstrate the resilience of the replication fork to natural barriers and the sensitivity of chromosome alignment to fork progression.
    Mesh-Begriff(e) Chromosome Segregation/genetics ; Chromosomes, Bacterial/genetics ; DNA Helicases/genetics ; DNA Replication/genetics ; DNA-Binding Proteins/genetics ; DNA-Binding Proteins/metabolism ; Escherichia coli/genetics ; Escherichia coli Proteins/genetics ; Escherichia coli Proteins/metabolism ; Macromolecular Substances/metabolism
    Chemische Substanzen DNA replication terminus site-binding protein, E coli ; DNA-Binding Proteins ; Escherichia coli Proteins ; Macromolecular Substances ; tus protein, E coli ; DNA Helicases (EC 3.6.4.-)
    Sprache Englisch
    Erscheinungsdatum 2016-05-10
    Erscheinungsland England
    Dokumenttyp Journal Article
    ZDB-ID 186809-3
    ISSN 1362-4962 ; 1362-4954 ; 0301-5610 ; 0305-1048
    ISSN (online) 1362-4962 ; 1362-4954
    ISSN 0301-5610 ; 0305-1048
    DOI 10.1093/nar/gkw397
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  6. Artikel ; Online: Electron beam fabrication of a microfluidic device for studying submicron-scale bacteria.

    Moolman, M Charl / Huang, Zhuangxiong / Krishnan, Sriram Tiruvadi / Kerssemakers, Jacob W J / Dekker, Nynke H

    Journal of nanobiotechnology

    2013  Band 11, Seite(n) 12

    Abstract: Background: Controlled restriction of cellular movement using microfluidics allows one to study individual cells to gain insight into aspects of their physiology and behaviour. For example, the use of micron-sized growth channels that confine individual ...

    Abstract Background: Controlled restriction of cellular movement using microfluidics allows one to study individual cells to gain insight into aspects of their physiology and behaviour. For example, the use of micron-sized growth channels that confine individual Escherichia coli has yielded novel insights into cell growth and death. To extend this approach to other species of bacteria, many of whom have dimensions in the sub-micron range, or to a larger range of growth conditions, a readily-fabricated device containing sub-micron features is required.
    Results: Here we detail the fabrication of a versatile device with growth channels whose widths range from 0.3 μm to 0.8 μm. The device is fabricated using electron beam lithography, which provides excellent control over the shape and size of different growth channels and facilitates the rapid-prototyping of new designs. Features are successfully transferred first into silicon, and subsequently into the polydimethylsiloxane that forms the basis of the working microfluidic device. We demonstrate that the growth of sub-micron scale bacteria such as Lactococcus lactis or Escherichia coli cultured in minimal medium can be followed in such a device over several generations.
    Conclusions: We have presented a detailed protocol based on electron beam fabrication together with specific dry etching procedures for the fabrication of a microfluidic device suited to study submicron-sized bacteria. We have demonstrated that both Gram-positive and Gram-negative bacteria can be successfully loaded and imaged over a number of generations in this device. Similar devices could potentially be used to study other submicron-sized organisms under conditions in which the height and shape of the growth channels are crucial to the experimental design.
    Mesh-Begriff(e) Dimethylpolysiloxanes ; Electrons ; Escherichia coli/cytology ; Escherichia coli/growth & development ; Fluorescent Dyes/metabolism ; Gold ; Kymography ; Lactococcus lactis/cytology ; Lactococcus lactis/growth & development ; Microfluidic Analytical Techniques/instrumentation ; Microscopy, Electron, Scanning ; Microtechnology/instrumentation ; Silicon ; Time Factors
    Chemische Substanzen Dimethylpolysiloxanes ; Fluorescent Dyes ; Gold (7440-57-5) ; Silicon (Z4152N8IUI)
    Sprache Englisch
    Erscheinungsdatum 2013-04-10
    Erscheinungsland England
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2100022-0
    ISSN 1477-3155 ; 1477-3155
    ISSN (online) 1477-3155
    ISSN 1477-3155
    DOI 10.1186/1477-3155-11-12
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  7. Artikel ; Online: Slow unloading leads to DNA-bound β2-sliding clamp accumulation in live Escherichia coli cells.

    Moolman, M Charl / Krishnan, Sriram Tiruvadi / Kerssemakers, Jacob W J / van den Berg, Aafke / Tulinski, Pawel / Depken, Martin / Reyes-Lamothe, Rodrigo / Sherratt, David J / Dekker, Nynke H

    Nature communications

    2014  Band 5, Seite(n) 5820

    Abstract: The ubiquitous sliding clamp facilitates processivity of the replicative polymerase and acts as a platform to recruit proteins involved in replication, recombination and repair. While the dynamics of the E. coli β2-sliding clamp have been characterized ... ...

    Abstract The ubiquitous sliding clamp facilitates processivity of the replicative polymerase and acts as a platform to recruit proteins involved in replication, recombination and repair. While the dynamics of the E. coli β2-sliding clamp have been characterized in vitro, its in vivo stoichiometry and dynamics remain unclear. To probe both β2-clamp dynamics and stoichiometry in live E. coli cells, we use custom-built microfluidics in combination with single-molecule fluorescence microscopy and photoactivated fluorescence microscopy. We quantify the recruitment, binding and turnover of β2-sliding clamps on DNA during replication. These quantitative in vivo results demonstrate that numerous β2-clamps in E. coli remain on the DNA behind the replication fork for a protracted period of time, allowing them to form a docking platform for other enzymes involved in DNA metabolism.
    Mesh-Begriff(e) DNA Polymerase III/genetics ; DNA Polymerase III/metabolism ; DNA Repair ; DNA Replication ; DNA, Bacterial/chemistry ; DNA, Bacterial/genetics ; DNA, Bacterial/metabolism ; Escherichia coli/genetics ; Escherichia coli/metabolism ; Microfluidic Analytical Techniques ; Microscopy, Fluorescence ; Recombination, Genetic ; Time-Lapse Imaging
    Chemische Substanzen DNA, Bacterial ; DNA Polymerase III (EC 2.7.7.-)
    Sprache Englisch
    Erscheinungsdatum 2014-12-18
    Erscheinungsland England
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 2041-1723
    ISSN (online) 2041-1723
    DOI 10.1038/ncomms6820
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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