scholarly journals The ESCRT-III isoforms CHMP2A and CHMP2B display different effects on membranes upon polymerization

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Maryam Alqabandi ◽  
Nicola de Franceschi ◽  
Sourav Maity ◽  
Nolwenn Miguet ◽  
Marta Bally ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Multivesicular Body ◽  
Physical Characteristics ◽  
Membrane Remodeling ◽  
Biomimetic Systems ◽  
Mechanical Effects ◽  
Reticular Structure ◽  
Micrometer Scale ◽  
Lipid Specificity ◽  
Catalyzed Membrane

Abstract Background ESCRT-III proteins are involved in many membrane remodeling processes including multivesicular body biogenesis as first discovered in yeast. In humans, ESCRT-III CHMP2 exists as two isoforms, CHMP2A and CHMP2B, but their physical characteristics have not been compared yet. Results Here, we use a combination of techniques on biomimetic systems and purified proteins to study their affinity and effects on membranes. We establish that CHMP2B binding is enhanced in the presence of PI(4,5)P2 lipids. In contrast, CHMP2A does not display lipid specificity and requires CHMP3 for binding significantly to membranes. On the micrometer scale and at moderate bulk concentrations, CHMP2B forms a reticular structure on membranes whereas CHMP2A (+CHMP3) binds homogeneously. Thus, CHMP2A and CHMP2B unexpectedly induce different mechanical effects to membranes: CHMP2B strongly rigidifies them while CHMP2A (+CHMP3) has no significant effect. Conclusions We therefore conclude that CHMP2B and CHMP2A exhibit different mechanical properties and might thus contribute differently to the diverse ESCRT-III-catalyzed membrane remodeling processes.

scholarly journals The ESCRT-III Isoforms CHMP2A And CHMP2B Display Different Effects On Membranes Upon Polymerization

2019 ◽  
Author(s):  
Maryam Alqabandi ◽  
Nicola de Franceschi ◽  
Nolwenn Miguet ◽  
Sourav Maity ◽  
Marta Bally ◽  
...  
Keyword(s):  
Multivesicular Body ◽  
Physical Characteristics ◽  
Membrane Remodeling ◽  
Biomimetic Systems ◽  
Mechanical Effects ◽  
Reticular Structure ◽  
Micrometer Scale ◽  
Lipid Specificity

ABSTRACTESCRT-III proteins are involved in many membrane remodeling processes including multivesicular body biogenesis as first discovered in yeast. In humans, CHMP2 exists as two potential isoforms, CHMP2A and CHMP2B, but their physical characteristics have not been compared yet. Here, we use a combination of technics on biomimetic systems and purified proteins to study their affinity and effects on membranes. We establish that CHMP2B binding is enhanced in the presence of PI(4,5)P2 lipids. In contrast, CHMP2A does not display lipid specificity and requires CHMP3 for binding significantly to membranes. On the micrometer scale and at moderate bulk concentrations, CHMP2B forms a reticular structure on membranes whereas CHMP2A (+CHMP3) binds homogeneously. Eventually, CHMP2A and CHMP2B unexpectedly induce different mechanical effects to membranes: CHMP2B strongly rigidifies them while CHMP2A (+CHMP3) has no significant effect. Altogether, we conclude that CHMP2B and CHMP2A cannot be considered as isoforms and might thus contribute differently to membrane remodeling processes.

scholarly journals Structure and assembly of ESCRT-III helical Vps24 filaments

2020 ◽  
Vol 6 (34) ◽  
pp. eaba4897 ◽  
Author(s):  
Stefan T. Huber ◽  
Siavash Mostafavi ◽  
Simon A. Mortensen ◽  
Carsten Sachse
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mixed Type ◽  
Multivesicular Body ◽  
Cellular Membrane ◽  
Membrane Remodeling ◽  
Tubular Structures ◽  
Geometric Properties ◽  
Open Conformation ◽  
Assembly Structure ◽  
Polymeric Structures

ESCRT-III proteins mediate a range of cellular membrane remodeling activities such as multivesicular body biogenesis, cytokinesis, and viral release. Critical to these processes is the assembly of ESCRT-III subunits into polymeric structures. In this study, we determined the cryo-EM structure of a helical assembly of Saccharomyces cerevisiae Vps24 at 3.2-Å resolution and found that Vps24 adopts an elongated open conformation. Vps24 forms a domain-swapped dimer extended into protofilaments that associate into a double-stranded apolar filament. We demonstrate that, upon binding negatively charged lipids, Vps24 homopolymer filaments undergo partial disassembly into shorter filament fragments and oligomers. Upon the addition of Vps24, Vps2, and Snf7, liposomes are deformed into neck and tubular structures by an ESCRT-III heteropolymer coat. The filamentous Vps24 homopolymer assembly structure and interaction studies reveal how Vps24 could introduce unique geometric properties to mixed-type ESCRT-III heteropolymers and contribute to the process of membrane scission events.

scholarly journals Nanotechnology in Enhanced Oil Recovery

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1073 ◽  
Author(s):  
Goshtasp Cheraghian ◽  
Sara Rostami ◽  
Masoud Afrand
Keyword(s):  
Mechanical Properties ◽  
Interfacial Tension ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Physical And Mechanical Properties ◽  
Physical Characteristics ◽  
Oil Water ◽  
Very High

Nanoparticles (NPs) are known as important nanomaterials for a broad range of commercial and research applications owing to their physical characteristics and properties. Currently, the demand for NPs for use in enhanced oil recovery (EOR) is very high. The use of NPs can drastically benefit EOR by changing the wettability of the rock, improving the mobility of the oil drop and decreasing the interfacial tension (IFT) between oil/water. This paper focuses on a review of the application of NPs in the flooding process, the effect of NPs on wettability and the IFT. The study also presents a review of several investigations about the most common NPs, their physical and mechanical properties and benefits in EOR.

Test of Physical Mechanical Properties of Gingko，Hickory Nut and their Stalks

2012 ◽  
Vol 479-481 ◽  
pp. 1145-1150
Author(s):  
Xiao Feng Xu ◽  
Wen Bin Yao ◽  
Jiu Hua Xu ◽  
Wei Zhang
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Testing Machine ◽  
Physical Characteristics ◽  
Harvest Time ◽  
Cutting Resistance ◽  
Moisture Contents ◽  
Universal Testing ◽  
The Impact ◽  
Physical Mechanics

In order to get the physical mechanics of gingko，hickory nut and their stalks, microprocessor controlled electronic universal testing machine (WDW-5E) was used to study the basic physical characteristics，pulling resistance and cutting resistance of their stalk in different harvest time and moisture contents. The impact of physical mechanics of cones and stalks on the picking process were analyzed and some concrete suggestions were put forward in the paper. This experimental study provides an important theory basis on designing and manufacturing different cones picking machine.

Effects of CaCO3 Modificator on Microstructure and Mechanical Properties of Cast AZ91 Magnesium Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 155-158
Author(s):  
Qu Dong Wang ◽  
Yang Zhao ◽  
Qing Hua Li
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Cleavage Fracture ◽  
Tensile Fracture ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Microstructure And Mechanical Properties ◽  
Reticular Structure ◽  
Az91 Magnesium ◽  
Alloy Increase

Effects of CaCO3 modificator on microstructure and mechanical properties of cast AZ91 Magnesium alloy have been investigated. Tensile fracture behavior of AZ91 alloys modified by CaCO3 has also been studied. Results show that CaCO3 modificator can obviously refine the grain of AZ91 magnesium alloy and Mg17Al12. Mg17Al12 in grain boundary of AZ91 alloy after modified by CaCO3 changes from continuous reticular structure to discontinuous reticular structure, even so much as granular structure and rod structure. After modified by 0.5wt% CaCO3 modificator, ultimate tensile strength, yield strength, impact toughness and elongation of AZ91 alloy increase from 186MPa to 200MPa, from 147MPa to 160MPa, from 4J to 9J and from 2.6% to 5%, respectively. And 0.5wt% CaCO3 modificator brings about an optimal refining effect. The study also shows that the fracture mechanism of modified AZ91 alloy is between cleavage fracture and quasi-cleavage fracture, which is as same as that of unmodified AZ91 alloy.

scholarly journals Factorial Study of Compressive Mechanical Properties and PrimaryIn VitroOsteoblast Response of PHBV/PLLA Scaffolds

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Naznin Sultana ◽  
Tareef Hayat Khan
Keyword(s):  
Mechanical Properties ◽  
Polymer Matrix ◽  
Tissue Regeneration ◽  
Degradation Rate ◽  
Bone Tissue Regeneration ◽  
Osteoblastic Cells ◽  
Composite Scaffolds ◽  
Biomimetic Systems ◽  
Human Osteoblastic Cells

For bone tissue regeneration, composite scaffolds containing biodegradable polymers and nanosized osteoconductive bioceramics have been regarded as promising biomimetic systems. Polymer blends of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(L-lactic acid) (PLLA) can be used as the polymer matrix to control the degradation rate. In order to render the scaffolds osteoconductive, nano-sized hydroxyapatite (nHA) particles can be incorporated into the polymer matrix. In the first part of this study, a factorial design approach to investigate the influence of materials on the initial compressive mechanical properties of the scaffolds was studied. In the second part, the protein adsorption behavior and the attachment and morphology of osteoblast-like cells (Saos-2) of the scaffoldsin vitrowere also studied. It was observed that nHA incorporated PHBV/PLLA composite scaffolds adsorbed more bovine serum albumin (BSA) protein than PHBV or PHBV/PLLA scaffolds.In vitrostudies also revealed that the attachment of human osteoblastic cells (SaOS-2) was significantly higher in nHA incorporated PHBV/PLLA composite scaffolds. From the SEM micrographs of nHA incorporated PHBV/PLLA composite scaffolds seeded with SaOS-2 cells after a 7-day cell culture period, it was observed that the cells were well expanded and spread in all directions on the scaffolds.

Characterization of the Naked Mole Rat Incisors: Chemical Composition, Microstructure and Mechanical Properties

2021 ◽  
pp. 1-10
Author(s):  
Hongyan Qi ◽  
Guixiong Gao ◽  
Huixin Wang ◽  
Yunhai Ma ◽  
Hubiao Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Lamellar Structure ◽  
Three Dimensional ◽  
Microstructure And Mechanical Properties ◽  
Inorganic Matter ◽  
Mole Rat ◽  
Naked Mole Rat ◽  
Reticular Structure

The naked mole rat incisors (NMRI) exhibit excellent mechanical properties, which makes it a good prototype for design and fabrication of bionic mechanical systems and materials. In this work, we characterized the chemical composition, microstructure and mechanical properties of NMRI, and further compared these properties with the laboratory rat incisors (LRI). We found that (1) Enamel and dentin are composed of organic matter, inorganic matter and water. The ratio of Ca/P in NMRI enamel is higher than that of LRI enamel. (2) The dentin has a porous structure. The enamel has a three-dimensional reticular structure, which is more complex, regular and denser than the lamellar structure of LRI enamel. (3) Enamel has anisotropy. Its longitudinal nano-hardness is greater than that of transverse nano-hardness, and both of them are higher than that of LRI enamel. Their nano-hardness and elastic modulus increase with the increment of distance from the enamel-dentin boundary. The nano-hardness of dentin is smaller than that of enamel. The chemical composition and microstructure are considered to be the reasons for the excellent properties of NMRI. The chemical composition and unique microstructure can provide inspiration and guidelines for the design of bionic machinery and materials.

scholarly journals Experimental Study on the Fracturing Behaviors and Mechanical Properties of Cracks under Coupled Hydro-Mechanical Effects in Rock-like Specimens

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1355 ◽  
Author(s):  
Yimeng Zhou ◽  
Cheng Zhao ◽  
Chunfeng Zhao ◽  
Chuangchuang Ma ◽  
Junfei Xie
Keyword(s):  
Mechanical Properties ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Hydraulic Pressure ◽  
External Compression ◽  
Compression Loading ◽  
Mechanical Effects ◽  
Secondary Cracks ◽  
Loading System ◽  
New Type

The artificial fracturing technique under coupled hydro-mechanical effects is widely used in many rock engineering. Therefore, the study on the fracturing behaviors and mechanical properties of hydro-mechanical coupled cracks is very crucial. In this study, a series of fracturing tests were conducted on the cylinder gypsum specimens with single pre-existing cracks using triaxial compression loading system. Water pressure was applied inside the pre-existing cracks and led to the specimen failure with external compression loading. A new type of cracks, namely horizontal coupled cracks (HCC), were found in some specimens. Macroscopic observations reveal that HCC, which were mainly caused by the hydraulic pressure, were different from any tensile wing cracks, shear secondary cracks, or shear anti-wing cracks. Subsequently, a microscopic study was performed using scanning electron microscope (SEM), the outcomes suggest that: (1) Shear fracturing zones (SFZ) and tensile fracturing zones (TFZ) under coupled hydro-mechanical effects displayed distinct characteristics on orientations, length, and independence of gypsum grains; and (2) the HCC were tensile cracks when they just initiated from outer tips of pre-existing cracks. While tensile stress made major contribution to the specimen failure during the whole fracturing processes, the HCC became tensile and shear mixed cracks when the specimen was about to fail.

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