LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 10 of total 10

Search options

  1. Article: Functional phases define the response of the soil microbiome to environmental change.

    Lee, Kiseok Keith / Liu, Siqi / Crocker, Kyle / Huggins, David R / Tikhonov, Mikhail / Mani, Madhav / Kuehn, Seppe

    bioRxiv : the preprint server for biology

    2024  

    Abstract: A major challenge in microbiome research is understanding how natural communities respond to environmental change. The ecological, spatial, and chemical complexity of soils makes understanding the metabolic response of these communities to perturbations ... ...

    Abstract A major challenge in microbiome research is understanding how natural communities respond to environmental change. The ecological, spatial, and chemical complexity of soils makes understanding the metabolic response of these communities to perturbations particularly challenging. Here we measure the dynamics of respiratory nitrate utilization in >1,500 soil microcosms from 20 soil samples subjected to pH perturbations. Despite the complexity of the soil microbiome a minimal mathematical model with two parameters, the quantity of active biomass and the availability of a limiting nutrient, quantifies observed nitrate utilization dynamics across soils and pH perturbations. Across environmental perturbations, the model reveals the existence of three functional phases each with distinct qualitative dynamics of nitrate utilization over time: a phase where acidic perturbations induce cell death that limits metabolic activity, a nutrient-limiting phase where nitrate uptake is performed by dominant taxa that utilize nutrients released from the soil matrix, and a resurgent growth phase in basic conditions, where nutrients are in excess and rare taxa rapidly outgrow dominant populations. The underlying mechanism of each phase is predicted by our interpretable model and tested via amendment experiments, nutrient measurements, and sequencing. Finally, our data suggest that how soils transition between functional phases depends on the long-term history of environmental variation in the wild. Therefore, quantitative measurements and a minimal mathematical formalism reveal the existence of qualitative phases that capture the mechanisms and dynamics of a community responding to environmental change.
    Language English
    Publishing date 2024-03-28
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2024.03.15.584851
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  2. Article ; Online: A quantitative model for a nanoscale switch accurately predicts thermal actuation behavior.

    Crocker, Kyle / Johnson, Joshua / Pfeifer, Wolfgang / Castro, Carlos / Bundschuh, Ralf

    Nanoscale

    2021  Volume 13, Issue 32, Page(s) 13746–13757

    Abstract: Manipulation of temperature can be used to actuate DNA origami nano-hinges containing gold nanoparticles. We develop a physical model of this system that uses partition function analysis of the interaction between the nano-hinge and nanoparticle to ... ...

    Abstract Manipulation of temperature can be used to actuate DNA origami nano-hinges containing gold nanoparticles. We develop a physical model of this system that uses partition function analysis of the interaction between the nano-hinge and nanoparticle to predict the probability that the nano-hinge is open at a given temperature. The model agrees well with experimental data and predicts experimental conditions that allow the actuation temperature of the nano-hinge to be tuned over a range of temperatures from 30 °C to 45 °C. Additionally, the model identifies microscopic interactions that are important to the macroscopic behavior of the system, revealing surprising features of the system. This combination of physical insight and predictive potential is likely to inform future designs that integrate nanoparticles into dynamic DNA origami structures or use strand binding interactions to control dynamic DNA origami behavior. Furthermore, our modeling approach could be expanded to consider the incorporation, stability, and actuation of other types of functional elements or actuation mechanisms integrated into nucleic acid devices.
    MeSH term(s) DNA ; Gold ; Metal Nanoparticles ; Nucleic Acid Conformation ; Temperature
    Chemical Substances Gold (7440-57-5) ; DNA (9007-49-2)
    Language English
    Publishing date 2021-08-04
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/d1nr02873a
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  3. Article ; Online: Evolutionary advantage of a dissociative search mechanism in DNA mismatch repair.

    Crocker, Kyle / London, James / Medina, Andrés / Fishel, Richard / Bundschuh, Ralf

    Physical review. E

    2021  Volume 103, Issue 5-1, Page(s) 52404

    Abstract: Protein complexes involved in DNA mismatch repair diffuse along dsDNA as sliding clamps in order to locate a hemimethylated incision site. They have been observed to use a dissociative mechanism, in which two proteins, while continuously remaining ... ...

    Abstract Protein complexes involved in DNA mismatch repair diffuse along dsDNA as sliding clamps in order to locate a hemimethylated incision site. They have been observed to use a dissociative mechanism, in which two proteins, while continuously remaining attached to the DNA, sometimes associate into a single complex sliding on the DNA and sometimes dissociate into two independently sliding proteins. Here, we study the probability that these complexes locate a given target site via a semi-analytic, Monte Carlo calculation that tracks the association and dissociation of the sliding complexes. We compare such probabilities to those obtained using a nondissociative diffusive scan in the space of physically realistic diffusion constants, hemimethylated site distances, and total search times to determine the regions in which dissociative searching is more or less efficient than nondissociative searching. We conclude that the dissociative search mechanism is advantageous in the majority of the physically realistic parameter space, suggesting that the dissociative search mechanism confers an evolutionary advantage.
    MeSH term(s) DNA Mismatch Repair ; Diffusion
    Language English
    Publishing date 2021-07-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.103.052404
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  4. Article: Global patterns in gene content of soil microbiomes emerge from microbial interactions.

    Crocker, Kyle / Lee, Kiseok Keith / Chakraverti-Wuerthwein, Milena / Li, Zeqian / Tikhonov, Mikhail / Mani, Madhav / Gowda, Karna / Kuehn, Seppe

    bioRxiv : the preprint server for biology

    2023  

    Abstract: Microbial metabolism sustains life on Earth. Sequencing surveys of communities in hosts, oceans, and soils have revealed ubiquitous patterns linking the microbes present, the genes they possess, and local environmental conditions. One prominent ... ...

    Abstract Microbial metabolism sustains life on Earth. Sequencing surveys of communities in hosts, oceans, and soils have revealed ubiquitous patterns linking the microbes present, the genes they possess, and local environmental conditions. One prominent explanation for these patterns is environmental filtering: local conditions select strains with particular traits. However, filtering assumes ecological interactions do not influence patterns, despite the fact that interactions can and do play an important role in structuring communities. Here, we demonstrate the insufficiency of the environmental filtering hypothesis for explaining global patterns in topsoil microbiomes. Using denitrification as a model system, we find that the abundances of two characteristic genotypes trade-off with pH;
    Language English
    Publishing date 2023-11-15
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.05.31.542950
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  5. Book ; Online: Potential evolutionary advantage of a dissociative search mechanism in DNA mismatch repair

    Crocker, Kyle / London, James / Medina, Andrés / Fishel, Richard / Bundschuh, Ralf

    2020  

    Abstract: Protein complexes involved in DNA mismatch repair appear to diffuse along dsDNA in order to locate a hemimethylated incision site via a dissociative mechanism. Here, we study the probability that these complexes locate a given target site via a semi- ... ...

    Abstract Protein complexes involved in DNA mismatch repair appear to diffuse along dsDNA in order to locate a hemimethylated incision site via a dissociative mechanism. Here, we study the probability that these complexes locate a given target site via a semi-analytic, Monte Carlo calculation that tracks the association and dissociation of the complexes. We compare such probabilities to those obtained using a non-dissociative diffusive scan, and determine that for experimentally observed diffusion constants, search distances, and search durations $\textit{in vitro}$, there is neither a significant advantage nor disadvantage associated with the dissociative mechanism in terms of probability of successful search, and that both search mechanisms are highly efficient for a majority of hemimethylated site distances. Furthermore, we examine the space of physically realistic diffusion constants, hemimethylated site distances, and association lifetimes and determine the regions in which dissociative searching is more or less efficient than non-dissociative searching. We conclude that the dissociative search mechanism is advantageous in the majority of the physically realistic parameter space.
    Keywords Quantitative Biology - Subcellular Processes ; Physics - Biological Physics
    Subject code 612
    Publishing date 2020-12-17
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  6. Article ; Online: High-Force Application by a Nanoscale DNA Force Spectrometer.

    Darcy, Michael / Crocker, Kyle / Wang, Yuchen / Le, Jenny V / Mohammadiroozbahani, Golbarg / Abdelhamid, Mahmoud A S / Craggs, Timothy D / Castro, Carlos E / Bundschuh, Ralf / Poirier, Michael G

    ACS nano

    2022  Volume 16, Issue 4, Page(s) 5682–5695

    Abstract: The ability to apply and measure high forces (>10 pN) on the nanometer scale is critical to the development of nanomedicine, molecular robotics, and the understanding of biological processes such as chromatin condensation, membrane deformation, and viral ...

    Abstract The ability to apply and measure high forces (>10 pN) on the nanometer scale is critical to the development of nanomedicine, molecular robotics, and the understanding of biological processes such as chromatin condensation, membrane deformation, and viral packaging. Established force spectroscopy techniques including optical traps, magnetic tweezers, and atomic force microscopy rely on micron-sized or larger handles to apply forces, limiting their applications within constrained geometries including cellular environments and nanofluidic devices. A promising alternative to these approaches is DNA-based molecular calipers. However, this approach is currently limited to forces on the scale of a few piconewtons. To study the force application capabilities of DNA devices, we implemented DNA origami nanocalipers with tunable mechanical properties in a geometry that allows application of force to rupture a DNA duplex. We integrated static and dynamic single-molecule characterization methods and statistical mechanical modeling to quantify the device properties including force output and dynamic range. We found that the thermally driven dynamics of the device are capable of applying forces of at least 20 piconewtons with a nanometer-scale dynamic range. These characteristics could eventually be used to study other biomolecular processes such as protein unfolding or to control high-affinity interactions in nanomechanical devices or molecular robots.
    MeSH term(s) DNA/chemistry ; Nanotechnology/methods ; Microscopy, Atomic Force ; Optical Tweezers ; Mechanical Phenomena
    Chemical Substances DNA (9007-49-2)
    Language English
    Publishing date 2022-04-06
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, Non-U.S. Gov't ; Research Support, N.I.H., Extramural
    ISSN 1936-086X
    ISSN (online) 1936-086X
    DOI 10.1021/acsnano.1c10698
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  7. Article ; Online: Quantitative Modeling of Nucleosome Unwrapping from Both Ends.

    Zhao, Dengke / Le, Jenny V / Darcy, Michael A / Crocker, Kyle / Poirier, Michael G / Castro, Carlos / Bundschuh, Ralf

    Biophysical journal

    2019  Volume 117, Issue 11, Page(s) 2204–2216

    Abstract: In eukaryotic cells, DNA is packaged into chromatin where nucleosomes are the basic packaging unit. Important cellular processes including gene expression, DNA replication, and DNA repair require nucleosomal DNA to be unwrapped so that functional ... ...

    Abstract In eukaryotic cells, DNA is packaged into chromatin where nucleosomes are the basic packaging unit. Important cellular processes including gene expression, DNA replication, and DNA repair require nucleosomal DNA to be unwrapped so that functional proteins can access their target sites, which otherwise are sterically occluded. A key question in this process is what the unwrapped conformations individual nucleosomes adopt within chromatin are. Here, we develop a concurrent nucleosome unwrapping model to address this question. We hypothesize that for a given end-to-end distance of the nucleosomal DNA, the nucleosomal DNA stochastically unwraps from the histone core from both ends independently and that this combination of unwrapping from both sides results in a significant increase in the average distance between the DNA extending from both sides of the nucleosomes. We test our model on recently published experiments using a DNA origami nanocaliper that quantifies nucleosome unwrapping and achieve good agreement between experiment and model prediction. We then investigate the DNA origami caliper distribution when attached to a hexasome (a nucleosome lacking an H2A/H2B dimer). A significant shift in the caliper angle distribution caused by the asymmetric structural features of the hexasome seen experimentally is consistent with the model. Our modeling approach may be more broadly useful to the interpretation of other studies of nucleosome dynamics, chromatin dynamics, and regulatory processes involving nucleosome unwrapping, as well as more generally to optimization of future DNA origami designs to probe mechanical properties of biomolecules.
    MeSH term(s) Base Sequence ; DNA/chemistry ; DNA/genetics ; DNA/metabolism ; Models, Molecular ; Nanostructures/chemistry ; Nucleosomes/chemistry ; Nucleosomes/metabolism ; Thermodynamics
    Chemical Substances Nucleosomes ; DNA (9007-49-2)
    Language English
    Publishing date 2019-10-30
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 218078-9
    ISSN 1542-0086 ; 0006-3495
    ISSN (online) 1542-0086
    ISSN 0006-3495
    DOI 10.1016/j.bpj.2019.09.048
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  8. Article ; Online: A nanoscale DNA force spectrometer capable of applying tension and compression on biomolecules.

    Wang, Yuchen / Le, Jenny V / Crocker, Kyle / Darcy, Michael A / Halley, Patrick D / Zhao, Dengke / Andrioff, Nick / Croy, Cassie / Poirier, Michael G / Bundschuh, Ralf / Castro, Carlos E

    Nucleic acids research

    2021  Volume 49, Issue 15, Page(s) 8987–8999

    Abstract: Single molecule force spectroscopy is a powerful approach to probe the structure, conformational changes, and kinetic properties of biological and synthetic macromolecules. However, common approaches to apply forces to biomolecules require expensive and ... ...

    Abstract Single molecule force spectroscopy is a powerful approach to probe the structure, conformational changes, and kinetic properties of biological and synthetic macromolecules. However, common approaches to apply forces to biomolecules require expensive and cumbersome equipment and relatively large probes such as beads or cantilevers, which limits their use for many environments and makes integrating with other methods challenging. Furthermore, existing methods have key limitations such as an inability to apply compressive forces on single molecules. We report a nanoscale DNA force spectrometer (nDFS), which is based on a DNA origami hinge with tunable mechanical and dynamic properties. The angular free energy landscape of the nDFS can be engineered across a wide range through substitution of less than 5% of the strand components. We further incorporate a removable strut that enables reversible toggling of the nDFS between open and closed states to allow for actuated application of tensile and compressive forces. We demonstrate the ability to apply compressive forces by inducing a large bend in a 249bp DNA molecule, and tensile forces by inducing DNA unwrapping of a nucleosome sample. These results establish a versatile tool for force spectroscopy and robust methods for designing nanoscale mechanical devices with tunable force application.
    MeSH term(s) Bioengineering ; Biomechanical Phenomena ; DNA/chemistry ; Nanostructures/chemistry ; Nucleosomes/chemistry ; Spectrum Analysis
    Chemical Substances Nucleosomes ; DNA (9007-49-2)
    Language English
    Publishing date 2021-08-02
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    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/gkab656
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  9. Article: Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles.

    Gupton, John T / Telang, Nakul / Gazzo, Dominic F / Barelli, Peter J / Lescalleet, Kristin E / Fagan, Jonathan W / Mills, Brandon J / Finzel, Kara L / Kanters, Rene P F / Crocker, Kyle R / Dudek, Sean T / Lariviere, Corinne M / Smith, Stanton Q / Keertikar, Kartik M

    Tetrahedron

    2013  Volume 69, Issue 29, Page(s) 5829–5840

    Abstract: The preparation of an indole appended vinamidinium salt, an indole appended vinylogous amide and an indole appended chloroenal are described. The subsequent regiospecific conversion of these indole containing building blocks to functionalized pyrazoles ... ...

    Abstract The preparation of an indole appended vinamidinium salt, an indole appended vinylogous amide and an indole appended chloroenal are described. The subsequent regiospecific conversion of these indole containing building blocks to functionalized pyrazoles and pyrroles is detailed.
    Language English
    Publishing date 2013-03-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 204285-x
    ISSN 1464-5416 ; 0040-4020 ; 0563-2064
    ISSN (online) 1464-5416
    ISSN 0040-4020 ; 0563-2064
    DOI 10.1016/j.tet.2013.05.045
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  10. Article: Preparation of indole containing building blocks for the regiospecific construction of indole appended pyrazoles and pyrroles

    Gupton, John T / Telang, Nakul / Gazzo, Dominic F / Barelli, Peter J / Lescalleet, Kristin E / Fagan, Jonathan W / Mills, Brandon J / Finzel, Kara L / Kanters, Rene P.F / Crocker, Kyle R / Dudek, Sean T / Lariviere, Corinne M / Smith, Stanton Q / Keertikar, Kartik M

    Tetrahedron. 2013 July 22, v. 69, no. 29

    2013  

    Abstract: The preparation of an indole appended vinamidinium salt, an indole appended vinylogous amide and an indole appended chloroenal are described. The subsequent regiospecific conversion of these indole containing building blocks to functionalized pyrazoles ... ...

    Abstract The preparation of an indole appended vinamidinium salt, an indole appended vinylogous amide and an indole appended chloroenal are described. The subsequent regiospecific conversion of these indole containing building blocks to functionalized pyrazoles and pyrroles is detailed.
    Keywords chemical reactions ; chemical structure ; pyrazoles ; pyrroles
    Language English
    Dates of publication 2013-0722
    Size p. 5829-5840.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 204285-x
    ISSN 1464-5416 ; 0040-4020 ; 0563-2064
    ISSN (online) 1464-5416
    ISSN 0040-4020 ; 0563-2064
    DOI 10.1016/j.tet.2013.05.045
    Database NAL-Catalogue (AGRICOLA)

    More links

    Kategorien

To top