scholarly journals Magnetic resonance measurements of cellular and sub-cellular membrane structures in live and fixed neural tissue

2019 ◽  
Author(s):  
Nathan H. Williamson ◽  
Rea Ravin ◽  
Dan Benjamini ◽  
Hellmut Merkle ◽  
Melanie Falgairolle ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Permanent Magnet ◽  
Lipid Membranes ◽  
Neural Tissue ◽  
Cellular Membrane ◽  
Membrane Structures ◽  
Tissue Microstructure ◽  
Exchange Spectroscopy ◽  
Time Changes ◽  
Tissue Diffusion

We develop magnetic resonance (MR) methods for measuring real-time changes of tissue microstructure and membrane permeability of live and fixed neural tissue. Diffusion and exchange MR measurements are performed using the large static gradient produced by a single-sided permanent magnet. Using tissue delipidation methods, we show that water diffusion is restricted solely by lipid membranes. Most of the diffusion signal can be assigned to water in tissue which is far from membranes. The remaining 25% can be assigned to water restricted on length scales of roughly a micron or less, near or within membrane structures at the cellular, organelle, and vesicle levels. Diffusion exchange spectroscopy measures water exchanging between membrane structures and free environments at 100 s−1.

scholarly journals Magnetic resonance measurements of cellular and sub-cellular membrane structures in live and fixed neural tissue

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Nathan H Williamson ◽  
Rea Ravin ◽  
Dan Benjamini ◽  
Hellmut Merkle ◽  
Melanie Falgairolle ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Permanent Magnet ◽  
Lipid Membranes ◽  
Neural Tissue ◽  
Cellular Membrane ◽  
Time Measurement ◽  
Membrane Structures ◽  
Tissue Microstructure ◽  
Real Time Measurement ◽  
Exchange Spectroscopy

We develop magnetic resonance (MR) methods for real-time measurement of tissue microstructure and membrane permeability of live and fixed excised neonatal mouse spinal cords. Diffusion and exchange MR measurements are performed using the strong static gradient produced by a single-sided permanent magnet. Using tissue delipidation methods, we show that water diffusion is restricted solely by lipid membranes. Most of the diffusion signal can be assigned to water in tissue which is far from membranes. The remaining 25% can be assigned to water restricted on length scales of roughly a micron or less, near or within membrane structures at the cellular, organelle, and vesicle levels. Diffusion exchange spectroscopy measures water exchanging between membrane structures and free environments at 100 s-1.

scholarly journals Author response: Magnetic resonance measurements of cellular and sub-cellular membrane structures in live and fixed neural tissue

2019 ◽  
Author(s):  
Nathan H Williamson ◽  
Rea Ravin ◽  
Dan Benjamini ◽  
Hellmut Merkle ◽  
Melanie Falgairolle ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Neural Tissue ◽  
Cellular Membrane ◽  
Author Response ◽  
Membrane Structures

scholarly journals Enhanced Stability of Lipid Structures by Dip-Pen Nanolithography on Block-Type MPC Copolymer

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2768
Author(s):  
Hui-Yu Liu ◽  
Ravi Kumar ◽  
Madoka Takai ◽  
Michael Hirtz
Keyword(s):  
Lipid Membranes ◽  
Silicon Oxide ◽  
Lipid Membrane ◽  
Block Type ◽  
Membrane Structures ◽  
Solid Supports ◽  
Biomedical Sensing ◽  
The Stability ◽  
Lipid Structures ◽  
Dip Pen Nanolithography

Biomimetic lipid membranes on solid supports have been used in a plethora of applications, including as biosensors, in research on membrane proteins or as interfaces in cell experiments. For many of these applications, structured lipid membranes, e.g., in the form of arrays with features of different functionality, are highly desired. The stability of these features on a given substrate during storage and in incubation steps is key, while at the same time the substrate ideally should also exhibit antifouling properties. Here, we describe the highly beneficial properties of a 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer for the stability of supported lipid membrane structures generated by dip-pen nanolithography with phospholipids (L-DPN). The MPC copolymer substrates allow for more stable and higher membrane stack structures in comparison to other hydrophilic substrates, like glass or silicon oxide surfaces. The structures remain highly stable under immersion in liquid and subsequent incubation and washing steps. This allows multiplexed functionalization of lipid arrays with antibodies via microchannel cantilever spotting (µCS), without the need of orthogonal binding tags for each antibody type. The combined properties of the MPC copolymer substrate demonstrate a great potential for lipid-based biomedical sensing and diagnostic platforms.

scholarly journals A putative N-BAR-domain protein is crucially required for the development of hyphae tip appressorium-like structure and its plant infection in Magnaporthe oryzae

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Lili Lin ◽  
Xiaomin Chen ◽  
Ammarah Shabbir ◽  
Si Chen ◽  
Xuewen Chen ◽  
...  
Keyword(s):  
Magnaporthe Oryzae ◽  
Lipid Membranes ◽  
Cellular Membrane ◽  
Gene Replacement ◽  
Bar Domain ◽  
Plant Infection ◽  
Expression Of Genes ◽  
Peripheral Proteins ◽  
Bar Domain Proteins ◽  
Replacement Technique

Abstract Membrane remodeling modulates many biological processes. The binding of peripheral proteins to lipid membranes results in membrane invaginations and protrusions, which regulate essential intra-cellular membrane and extra-cellular trafficking events. Proteins that bind and re-shape bio-membranes have been identified and extensively investigated. The Bin/Amphiphysin/Rvs (BAR) domain proteins are crescent-shape and play a conserved role in tubulation and sculpturing of cell membranes. We deployed targeted gene replacement technique to functionally characterize two hypothetical proteins (MoBar-A and MoBar-B) containing unitary N-BAR domain in Magnaporthe oryzae. The results obtained from phenotypic examinations showed that MoBAR-A deletion exerted a significant reduction in the growth of the defective ∆Mobar-A strain. Also, MoBAR-A disruption exclusively compromised hyphae-mediated infection. Additionally, the targeted replacement of MoBAR-A suppressed the expression of genes associated with the formation of hyphae tip appressorium-like structure in M. oryzae. Furthermore, single as well as combined deletion of MoBAR-A and MoBAR-B down-regulated the expression of nine different membrane-associated genes. From these results, we inferred that MoBAR-A plays a key and unique role in the pathogenesis of M. oryzae through direct or indirect regulation of the development of appressorium-like structures developed by hyphae tip. Taken together, these results provide unique insights into the direct contribution of the N-BAR domain proteins to morphological, reproduction, and infectious development of M. oryzae.

scholarly journals Endoplasmic Reticulum Detergent-Resistant Membranes Accommodate Hepatitis C Virus Proteins for Viral Assembly

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 487 ◽  
Author(s):  
Audrey Boyer ◽  
Julie Dreneau ◽  
Amélie Dumans ◽  
Julien Burlaud-Gaillard ◽  
Anne Bull-Maurer ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Protein Interactions ◽  
Gradient Centrifugation ◽  
Cellular Membrane ◽  
Structural Protein ◽  
Membrane Structures ◽  
Detergent Resistant Membranes ◽  
Lysis Buffer

During Hepatitis C virus (HCV) morphogenesis, the non-structural protein 2 (NS2) brings the envelope proteins 1 and 2 (E1, E2), NS3, and NS5A together to form a complex at the endoplasmic reticulum (ER) membrane, initiating HCV assembly. The nature of the interactions in this complex is unclear, but replication complex and structural proteins have been shown to be associated with cellular membrane structures called detergent-resistant membranes (DRMs). We investigated the role of DRMs in NS2 complex formation, using a lysis buffer combining Triton and n-octyl glucoside, which solubilized both cell membranes and DRMs. When this lysis buffer was used on HCV-infected cells and the resulting lysates were subjected to flotation gradient centrifugation, all viral proteins and DRM-resident proteins were found in soluble protein fractions. Immunoprecipitation assays demonstrated direct protein–protein interactions between NS2 and E2 and E1 proteins, and an association of NS2 with NS3 through DRMs. The well-folded E1E2 complex and NS5A were not associated, instead interacting separately with the NS2-E1-E2-NS3 complex through less stable DRMs. Core was also associated with NS2 and the E1E2 complex through these unstable DRMs. We suggest that DRMs carrying this NS2-E1-E2-NS3-4A-NS5A-core complex may play a central role in HCV assembly initiation, potentially as an assembly platform.

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