The Experts below are selected from a list of 28146 Experts worldwide ranked by ideXlab platform

Richard D Leapman - One of the best experts on this subject based on the ideXlab platform.

  • use of dual Electron Probes reveals the role of ferritin as an iron depot in ex vivo erythropoiesis
    iScience, 2021
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    In the finely regulated process of mammalian erythropoiesis, the path of the labile iron pool into mitochondria for heme production is not well understood. Existing models for erythropoiesis do not include a central role for the ubiquitous iron storage protein ferritin; one model proposes that incoming endosomal Fe3+ bound to transferrin enters the cytoplasm through an ion transporter after reduction to Fe2+ and is taken up into mitochondria through mitoferrin-1 transporter. Here, we apply a dual three-dimensional imaging and spectroscopic technique, based on scanned Electron Probes, to measure Fe3+ in ex vivo human hematopoietic stem cells. After seven days in culture, we observe cells displaying a highly specialized architecture with anchored clustering of mitochondria and massive accumulation of nanoparticles containing high iron concentrations localized to lysosomal storage depots, identified as ferritin. We hypothesize that lysosomal ferritin iron depots enable continued heme production after expulsion of most of the cellular machinery.

  • use of dual Electron Probes reveals role of ferritin in ex vivo erythropoiesis
    Social Science Research Network, 2021
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    In the finely regulated process of mammalian erythropoiesis, the path of the labile iron pool and its transport to mitochondria for heme production is not well understood1. Existing models for erythropoiesis do not involve a central role for the ubiquitous iron storage protein ferritin, but instead indicate that incoming endosomal Fe3+ attached to transferrin enters the cytoplasm through divalent metal ion transporters after reduction to Fe2+, and is immediately taken up into mitochondria through the mitoferrin-1 transporter. Here, we apply a dual 3D imaging and spectroscopic technique, based on scanned Electron Probes, to measure distributions of Fe3+ in ex vivo human erythropoietic stem cells. After seven days in culture, we find that the cells display a highly specialized architecture of organelles with anchored clustering of mitochondria and massive accumulation of nanoparticles containing high iron concentrations localized to lysosomal storage depots, which we identify as ferritin. Our results support the hypothesis that lysosomal ferritin iron depots are utilized by developing reticulocytes to continue heme production after much of the cellular machinery has been expelled.

  • use of dual Electron Probes reveals role of ferritin in erythropoiesis
    bioRxiv, 2019
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    Much is known about the finely regulated process of mammalian erythropoiesis that occurs in the bone marrow, whereby erythropoietic stem cells undergo terminal differentiation accompanied by enormous morphological changes to generate highly functional specialized red blood cells. However, a crucial step in erythropoiesis, the labile iron pool and its transport to mitochondria for heme production, is not well understood1. We apply a dual 3D imaging and spectroscopic technique, based on scanned Electron Probes, to measure distributions of ferritin iron-storage protein in ex vivo human erythropoietic stem cells, and to determine how those distributions change during terminal differentiation. After seven days of differentiation, the cells display a highly specialized architecture of organelles with anchored clustering of mitochondria and massive accumulation of Fe3+ in loaded ferritin cores localized to lysosomal storage depots, providing an iron source for heme production. Macrophages are not present in our ex vivo cultures, so they cannot be the source of the ferritin2. We suggest that lysosomal iron depots are required by developing reticulocytes while terminally differentiating and continuing to produce heme and globin, which assemble and concentrate to fill the cytoplasm after much of the cellular machinery is expelled.

  • comparison of 3 d cell and tissue imaging techniques based on scanning Electron Probes
    Biophysical Journal, 2017
    Co-Authors: E L Mcbride, Amith Rao, Guofeng Zhang, Irina D Pokrovskaya, Maria A Aronova, Brian Storrie, Richard D Leapman
    Abstract:

    The use of scanned Electron Probes, rather than the wide-beam illumination of standard transmission Electron microscopy, allows the structural biologist to image 3-D cellular and tissue ultrastructure by taking full advantage of the physical interactions between the incoming Electrons and the specimen. For example, in serial block face scanning Electron microscopy (SBF-SEM), a low-energy (∼1 keV Electron probe) produces a backscattered Electron signal originating from a thin approximately 25-nm layer below the face of a heavy-atom stained, resin-embedded block.

R Dwayne J Miller - One of the best experts on this subject based on the ideXlab platform.

  • nanofluidic cells with controlled pathlength and liquid flow for rapid high resolution in situ imaging with Electrons
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: C Mueller, Maher Harb, Jason R Dwyer, R Dwayne J Miller
    Abstract:

    The use of Electron Probes for in situ imaging of solution phase systems has been a long held objective, largely driven by the prospect of atomic resolution of molecular structural dynamics relevant to chemistry and biology. Here, we present a nanofluidic sample cell with active feedback to maintain stable flow conditions for pathlengths varying from 45 nm to several 100 nm, over a useable viewing area of 50 × 50 μm. Using this concept, we demonstrate nanometer resolution for imaging weakly scattering polymer and highly scattering nanoparticles side by side with a conventional transmission microscope. The ability to flow liquids allows control over sample content and on-the-fly sample exchange, opening up the field of high-throughput Electron microscopy. The nanofluidic cell design is distinguished by straightforward, reliable, operation with external liquid specimen control for imaging in (scanning) transmission mode and holds great promise for reciprocal space imaging in femtosecond Electron diffraction...

  • femtosecond Electron diffraction heralding the era of atomically resolved dynamics
    Reports on Progress in Physics, 2011
    Co-Authors: German Sciaini, R Dwayne J Miller
    Abstract:

    One of the great dream experiments in Science is to directly observe atomic motions as they occur. Femtosecond Electron diffraction provided the first 'light' of sufficient intensity to achieve this goal by attaining atomic resolution to structural changes on the relevant timescales. This review covers the technical progress that made this new level of acuity possible and gives a survey of the new insights gained from an atomic level perspective of structural dynamics. Atomic level views of the simplest possible structural transition, melting, are discussed for a number of systems in which both thermal and purely Electronically driven atomic displacements can be correlated with the degree of directional bonding. Optical manipulation of charge distributions and effects on interatomic forces/bonding can be directly observed through the ensuing atomic motions. New phenomena involving strongly correlated Electron?lattice systems are also discussed in which optically induced changes in the potential energy landscape lead to ballistic structural changes. Concepts such as the structural order parameters are now directly observable at the atomic level of inspection to give a remarkable view of the extraordinary degree of cooperativity involved in strongly correlated Electron?lattice systems. These recent examples, in combination with time-resolved real space imaging now possible with Electron Probes, are truly defining an emerging field that holds great promise to make a significant impact in how we understand structural dynamics.This article is dedicated to the memory of Professor David John Hugh Cockayne, a world leader in Electron microscopy, who sadly passed away in December.

Maria A Aronova - One of the best experts on this subject based on the ideXlab platform.

  • use of dual Electron Probes reveals the role of ferritin as an iron depot in ex vivo erythropoiesis
    iScience, 2021
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    In the finely regulated process of mammalian erythropoiesis, the path of the labile iron pool into mitochondria for heme production is not well understood. Existing models for erythropoiesis do not include a central role for the ubiquitous iron storage protein ferritin; one model proposes that incoming endosomal Fe3+ bound to transferrin enters the cytoplasm through an ion transporter after reduction to Fe2+ and is taken up into mitochondria through mitoferrin-1 transporter. Here, we apply a dual three-dimensional imaging and spectroscopic technique, based on scanned Electron Probes, to measure Fe3+ in ex vivo human hematopoietic stem cells. After seven days in culture, we observe cells displaying a highly specialized architecture with anchored clustering of mitochondria and massive accumulation of nanoparticles containing high iron concentrations localized to lysosomal storage depots, identified as ferritin. We hypothesize that lysosomal ferritin iron depots enable continued heme production after expulsion of most of the cellular machinery.

  • use of dual Electron Probes reveals role of ferritin in ex vivo erythropoiesis
    Social Science Research Network, 2021
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    In the finely regulated process of mammalian erythropoiesis, the path of the labile iron pool and its transport to mitochondria for heme production is not well understood1. Existing models for erythropoiesis do not involve a central role for the ubiquitous iron storage protein ferritin, but instead indicate that incoming endosomal Fe3+ attached to transferrin enters the cytoplasm through divalent metal ion transporters after reduction to Fe2+, and is immediately taken up into mitochondria through the mitoferrin-1 transporter. Here, we apply a dual 3D imaging and spectroscopic technique, based on scanned Electron Probes, to measure distributions of Fe3+ in ex vivo human erythropoietic stem cells. After seven days in culture, we find that the cells display a highly specialized architecture of organelles with anchored clustering of mitochondria and massive accumulation of nanoparticles containing high iron concentrations localized to lysosomal storage depots, which we identify as ferritin. Our results support the hypothesis that lysosomal ferritin iron depots are utilized by developing reticulocytes to continue heme production after much of the cellular machinery has been expelled.

  • use of dual Electron Probes reveals role of ferritin in erythropoiesis
    bioRxiv, 2019
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    Much is known about the finely regulated process of mammalian erythropoiesis that occurs in the bone marrow, whereby erythropoietic stem cells undergo terminal differentiation accompanied by enormous morphological changes to generate highly functional specialized red blood cells. However, a crucial step in erythropoiesis, the labile iron pool and its transport to mitochondria for heme production, is not well understood1. We apply a dual 3D imaging and spectroscopic technique, based on scanned Electron Probes, to measure distributions of ferritin iron-storage protein in ex vivo human erythropoietic stem cells, and to determine how those distributions change during terminal differentiation. After seven days of differentiation, the cells display a highly specialized architecture of organelles with anchored clustering of mitochondria and massive accumulation of Fe3+ in loaded ferritin cores localized to lysosomal storage depots, providing an iron source for heme production. Macrophages are not present in our ex vivo cultures, so they cannot be the source of the ferritin2. We suggest that lysosomal iron depots are required by developing reticulocytes while terminally differentiating and continuing to produce heme and globin, which assemble and concentrate to fill the cytoplasm after much of the cellular machinery is expelled.

  • comparison of 3 d cell and tissue imaging techniques based on scanning Electron Probes
    Biophysical Journal, 2017
    Co-Authors: E L Mcbride, Amith Rao, Guofeng Zhang, Irina D Pokrovskaya, Maria A Aronova, Brian Storrie, Richard D Leapman
    Abstract:

    The use of scanned Electron Probes, rather than the wide-beam illumination of standard transmission Electron microscopy, allows the structural biologist to image 3-D cellular and tissue ultrastructure by taking full advantage of the physical interactions between the incoming Electrons and the specimen. For example, in serial block face scanning Electron microscopy (SBF-SEM), a low-energy (∼1 keV Electron probe) produces a backscattered Electron signal originating from a thin approximately 25-nm layer below the face of a heavy-atom stained, resin-embedded block.

Guofeng Zhang - One of the best experts on this subject based on the ideXlab platform.

  • use of dual Electron Probes reveals the role of ferritin as an iron depot in ex vivo erythropoiesis
    iScience, 2021
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    In the finely regulated process of mammalian erythropoiesis, the path of the labile iron pool into mitochondria for heme production is not well understood. Existing models for erythropoiesis do not include a central role for the ubiquitous iron storage protein ferritin; one model proposes that incoming endosomal Fe3+ bound to transferrin enters the cytoplasm through an ion transporter after reduction to Fe2+ and is taken up into mitochondria through mitoferrin-1 transporter. Here, we apply a dual three-dimensional imaging and spectroscopic technique, based on scanned Electron Probes, to measure Fe3+ in ex vivo human hematopoietic stem cells. After seven days in culture, we observe cells displaying a highly specialized architecture with anchored clustering of mitochondria and massive accumulation of nanoparticles containing high iron concentrations localized to lysosomal storage depots, identified as ferritin. We hypothesize that lysosomal ferritin iron depots enable continued heme production after expulsion of most of the cellular machinery.

  • use of dual Electron Probes reveals role of ferritin in ex vivo erythropoiesis
    Social Science Research Network, 2021
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    In the finely regulated process of mammalian erythropoiesis, the path of the labile iron pool and its transport to mitochondria for heme production is not well understood1. Existing models for erythropoiesis do not involve a central role for the ubiquitous iron storage protein ferritin, but instead indicate that incoming endosomal Fe3+ attached to transferrin enters the cytoplasm through divalent metal ion transporters after reduction to Fe2+, and is immediately taken up into mitochondria through the mitoferrin-1 transporter. Here, we apply a dual 3D imaging and spectroscopic technique, based on scanned Electron Probes, to measure distributions of Fe3+ in ex vivo human erythropoietic stem cells. After seven days in culture, we find that the cells display a highly specialized architecture of organelles with anchored clustering of mitochondria and massive accumulation of nanoparticles containing high iron concentrations localized to lysosomal storage depots, which we identify as ferritin. Our results support the hypothesis that lysosomal ferritin iron depots are utilized by developing reticulocytes to continue heme production after much of the cellular machinery has been expelled.

  • use of dual Electron Probes reveals role of ferritin in erythropoiesis
    bioRxiv, 2019
    Co-Authors: Maria A Aronova, Guofeng Zhang, Seungjae Noh, Colleen Byrnes, Emily Riehm Meier, Young C Kim, Richard D Leapman
    Abstract:

    Much is known about the finely regulated process of mammalian erythropoiesis that occurs in the bone marrow, whereby erythropoietic stem cells undergo terminal differentiation accompanied by enormous morphological changes to generate highly functional specialized red blood cells. However, a crucial step in erythropoiesis, the labile iron pool and its transport to mitochondria for heme production, is not well understood1. We apply a dual 3D imaging and spectroscopic technique, based on scanned Electron Probes, to measure distributions of ferritin iron-storage protein in ex vivo human erythropoietic stem cells, and to determine how those distributions change during terminal differentiation. After seven days of differentiation, the cells display a highly specialized architecture of organelles with anchored clustering of mitochondria and massive accumulation of Fe3+ in loaded ferritin cores localized to lysosomal storage depots, providing an iron source for heme production. Macrophages are not present in our ex vivo cultures, so they cannot be the source of the ferritin2. We suggest that lysosomal iron depots are required by developing reticulocytes while terminally differentiating and continuing to produce heme and globin, which assemble and concentrate to fill the cytoplasm after much of the cellular machinery is expelled.

  • comparison of 3 d cell and tissue imaging techniques based on scanning Electron Probes
    Biophysical Journal, 2017
    Co-Authors: E L Mcbride, Amith Rao, Guofeng Zhang, Irina D Pokrovskaya, Maria A Aronova, Brian Storrie, Richard D Leapman
    Abstract:

    The use of scanned Electron Probes, rather than the wide-beam illumination of standard transmission Electron microscopy, allows the structural biologist to image 3-D cellular and tissue ultrastructure by taking full advantage of the physical interactions between the incoming Electrons and the specimen. For example, in serial block face scanning Electron microscopy (SBF-SEM), a low-energy (∼1 keV Electron probe) produces a backscattered Electron signal originating from a thin approximately 25-nm layer below the face of a heavy-atom stained, resin-embedded block.

Juan Carlos Idrobo - One of the best experts on this subject based on the ideXlab platform.

  • detecting magnetic ordering with atomic size Electron Probes
    Advanced Structural and Chemical Imaging, 2016
    Co-Authors: Juan Carlos Idrobo, Jakob Spiegelberg, Jan Rusz, Christopher T. Symons, Claudia Cantoni, Michael A. Mcguire, Ranga Raju Vatsavai, Andrew R. Lupini
    Abstract:

    Although magnetism originates at the atomic scale, the existing spectroscopic techniques sensitive to magnetic signals only produce spectra with spatial resolution on a larger scale. However, recently, it has been theoretically argued that atomic size Electron Probes with customized phase distributions can detect magnetic circular dichroism. Here, we report a direct experimental real-space detection of magnetic circular dichroism in aberration-corrected scanning transmission Electron microscopy (STEM). Using an atomic size-aberrated Electron probe with a customized phase distribution, we reveal the checkerboard antiferromagnetic ordering of Mn moments in LaMnAsO by observing a dichroic signal in the Mn L-edge. The novel experimental setup presented here, which can easily be implemented in aberration-corrected STEM, opens new paths for probing dichroic signals in materials with unprecedented spatial resolution.

  • aberrated Electron Probes for magnetic spectroscopy with atomic resolution theory and practical aspects
    Physical Review B, 2016
    Co-Authors: Jan Rusz, Juan Carlos Idrobo
    Abstract:

    It was recently proposed that Electron magnetic circular dichroism can be measured in scanning transmission Electron microscopy with atomic resolution by tuning the phase distribution of an Electron beam. Here, we describe the theoretical and practical aspects for the detection of out-of-plane and in-plane magnetization utilizing atomic size Electron Probes. We present the calculated optimized astigmatic Probes and discuss how to achieve them experimentally.