Cell–cell adhesion is important for cell growth, tissue development, and neural network formation. Structures of cell adhesion molecules have been widely studied by crystallography, revealing the ...molecular details of adhesion interfaces. However, due to technical limitations, the overall structure and organization of adhesion molecules at cell adhesion interfaces has not been fully investigated. Here, we combine electron microscopy and other biophysical methods to characterize the structure of cell–cell adhesion mediated by the cell adhesion molecule Sidekick (Sidekick-1 and Sidekick-2) and obtain 3D views of the Sidekick-mediated adhesion interfaces as well as the organization of Sidekick molecules between cell membranes by electron tomography. The results suggest that the Ig-like domains and the fibronectin III (FnIII) domains of Sidekicks play different roles in cell adhesion. The Ig-like domains mediate the homophilic transinteractions bridging adjacent cells, while the FnIII domains interact with membranes, resulting in a tight adhesion interface between cells that may contribute to the specificity and plasticity of cell–cell contacts during cell growth and neural development.
The special organelle-located MAVS, STING and TLR3 are important for clearing viral infections. Although TLR4 triggers NF-κB activation to produce pro-inflammatory cytokines for bacterial clearance, ...effectors with special organelle localization have not been identified. Here, we screened more than 280 E3 ubiquitin ligases and discovered that the endoplasmic reticulum-located Hrd1 regulates TLR4-induced inflammation during bacterial infection. Hrd1 interacts directly with the deubiquitinating enzyme Usp15. Unlike the classical function of Hrd1 in endoplasmic reticulum-associated degradation, Usp15 is not degraded but loses its deubiquitinating activity for IκBα deubiquitination, resulting in excessive NF-κB activation. Importantly, Hrd1 deficiency in macrophages protects mice against lipopolysaccharide-induced septic shock, and knockdown of Usp15 in Hrd1-knockout macrophages restores the reduced IL-6 production. This study proposes that there is crosstalk between Hrd1 and TLR4, thereby linking the endoplasmic reticulum-plasma membrane function during bacterial infection.
Scavenger receptors are a superfamily of membrane-bound receptors that recognize both self and nonself targets. Scavenger receptor class A (SR-A) has five known members (SCARA1 to -5 or SR-A1 to ...-A5), which are type II transmembrane proteins that form homotrimers on the cell surface. SR-A members recognize various ligands and are involved in multiple biological pathways. Among them, SCARA5 can function as a ferritin receptor; however, the interaction between SCARA5 and ferritin has not been fully characterized. Here, we determine the crystal structures of the C-terminal scavenger receptor cysteine-rich (SRCR) domain of both human and mouse SCARA5 at 1.7 and 2.5 Å resolution, respectively, revealing three Ca2+-binding sites on the surface. Using biochemical assays, we show that the SRCR domain of SCARA5 recognizes ferritin in a Ca2+-dependent manner, and both L- and H-ferritin can be recognized by SCARA5 through the SRCR domain. Furthermore, the potential binding region of SCARA5 on the surface of ferritin is explored by mutagenesis studies. We also examine the interactions of ferritin with other SR-A members and find that SCARA1 (SR-A1, CD204) and MARCO (SR-A2, SCARA2), which are highly expressed on macrophages, also interact with ferritin. By contrast, SCARA3 and SCARA4, the two SR-A members without the SRCR domain, have no detectable binding with ferritin. Overall, these results provide a mechanistic view regarding the interactions between the SR-A members and ferritin that may help to understand the regulation of ferritin homeostasis by scavenger receptors.
The Down syndrome cell adhesion molecule (DSCAM) belongs to the immunoglobulin superfamily (IgSF) and plays important roles in neural development. It has a large ectodomain, including 10 Ig-like ...domains and 6 fibronectin III (FnIII) domains. Previous data have shown that DSCAM can mediate cell adhesion by forming homophilic dimers between cells and contributes to self-avoidance of neurites or neuronal tiling, which is important for neural network formation. However, the organization and assembly of DSCAM at cell adhesion interfaces has not been fully understood. Here we combine electron microscopy and other biophysical methods to characterize the structure of the DSCAM-mediated cell adhesion and generate three-dimensional views of the adhesion interfaces of DSCAM by electron tomography. The results show that mouse DSCAM forms a regular pattern at the adhesion interfaces. The Ig-like domains contribute to both
homophilic interactions and
assembly of the pattern, and the FnIII domains are crucial for the
pattern formation as well as the interaction with the cell membrane. By contrast, no obvious assembly pattern is observed at the adhesion interfaces mediated by mouse DSCAML1 or
DSCAMs, suggesting the different structural roles and mechanisms of DSCAMs in mediating cell adhesion and neural network formation.
A class of proteins known as antifreeze proteins (AFPs) appear in some organisms, allowing them to survive in low-temperature environments. These AFPs irreversibly adsorb to the surfaces of ice ...crystals and reduce the freezing temperature without significantly affecting the equilibrium melting point. Ice crystal growth is inhibited in the temperature gap between the melting point and the non-equilibrium freezing point, referred to as thermal hysteresis (TH). The irreversible adsorption of AFPs on the surfaces of ice crystals has been questioned because it is not consistent with the concentration dependence of the TH activity obtained from experimental studies. In this study, based on adsorption–inhibition theory, a random sequential adsorption model of AFPs was used to investigate the irreversible adsorption of hyperactive AFPs that have been found in the yellow mealworm beetle Tenebrio molitor (TmAFPs). The occupied fractions covered by TmAFP on ice crystal surfaces were obtained. The time and concentration dependence of the TH activity of TmAFP was analyzed. The theoretical results obtained from this model were consistent with reported experimental data. This work provides ideas and a theoretical basis for understanding the TH activity during the irreversible adsorption of AFPs.
Soil desiccation is a common physical phenomenon, which causes many geotechnical problems to unsaturated clayey soils. In this paper, a proposed model was incorporated into the original Discontinuous ...Deformation Analysis (DDA) to simulate the full desiccation process of a clayey soil from volume shrinkage to desiccation cracking and then to desiccation curling by focusing on soil suction. In this model, evaporation-induced soil volume shrinkage and suction-induced tensile failure were separately considered, in particular, soil suction was reasonably treated as an equivalent attractive force rather than a strength parameter. Then, a constrained desiccation test was simulated using the extended DDA model, and obtained numerical results were compared with the experimental results. The comparison results show that this model can capture the main features of the full desiccation process of the clayey soil. Moreover, the influences of soil suction and sample thickness on the desiccation cracking and curling were investigated, which agrees with the laboratory observations. This work aims to propose a novel yet simple model to reproduce the key characteristics of the soil’s full desiccation process, and the results demonstrate that the extended DDA model can be served as a promising approach to analyzing the full desiccation process of clayey soils.
•AC electric field (ACEF) acted on peanut protein isolate (PPI) structure and flavor.•Structure and volatile compounds analyzed quantitatively and qualitatively.•ACEF caused alteration of secondary ...and tertiary structure.•ACEF promising in improving structure and flavor of PPI.
The impacts of intensity and treating time of alternating current (AC) electric field (EF) on structure and volatile compounds of peanut protein were investigated for low denaturation. The secondary and tertiary structures, polar and weakly polar volatiles were characterized qualitatively and quantitatively using ultraviolet and fluorescence photospectrometry, free sulfhydryl and disulfide groups determination, and combination of gas chromatography and mass spectrometry. The results showed that the ACEF affected significantly proportions of α-helices, β-sheets, β-turns, and random coils as evidenced by Fourier transform infrared spectrometry. Blue shifts of UV and fluorescence spectra, increased surface hydrophobicity and disulfide bonds could be observed after ACEF treatments. The DB-WAX and DB-5MS columns for the polar and weakly polar volatile compound separation revealed that ACEF caused either disappearance or emerging of volatile compounds. The PCA demonstrated that the two principal components contributed about 70 % or more to the flavor and PLS-DA discriminated 18 key compounds.
High-sensitivity accelerometry has historically been employed to explore Earth sciences and advance resource-related industries, such as petroleum exploitation. The devices capable of such ...measurements, however, traditionally involve precise mechanical structures and consequent large dimensions. In this work, combined by micromechanical systems and grating-assisted interferometry, a closed-loop optical accelerometer with nano-g (ng) sensitivity is developed for microseismic observations. In order to lower the intrinsic thermal noise, a modified 8.84 Hz micromechanical spring-mass oscillator is designed and fabricated. Additionally, an active control system is equipped to stabilize the device temperature and thus enhance the low-frequency stability. Field tests demonstrate that the prototype has achieved a scale factor of 1195 V/g, along with a dynamic range of 1.12 mg and a bandwidth of about 7 Hz. Further, under the controlled 45 <inline-formula><tex-math notation="LaTeX">\pm</tex-math></inline-formula> 0.01 <inline-formula><tex-math notation="LaTeX">^\circ</tex-math></inline-formula>C temperature condition, complete terrestrial microsesimic peaks from 0.1 Hz to 3 Hz are tracked. After calibration by a reference seismometer, the device self-noise is determined as 2 ng/<inline-formula><tex-math notation="LaTeX">\sqrt{Hz}</tex-math></inline-formula> from 0.2 Hz to 4 Hz with a bias stability of 7.9 ng. The transducer and control circuits are both packaged within a 13.6<inline-formula><tex-math notation="LaTeX">\times 13.6\times</tex-math></inline-formula>12.8 cm<inline-formula><tex-math notation="LaTeX">^{3}</tex-math></inline-formula> insulated enclosure, making it advantageous for outdoor observations.
Background:
Fucoxanthin (FX), a xanthophyll pigment which occurs in marine brown algae with remarkable biological properties, has been proven to be safe for consumption by animals. Although FX has ...various pharmacological effects including anti-inflammatory, anti-tumor, anti-obesity, antioxidant, anti-diabetic, anti-malarial, and anti-lipid,
in vivo
protective effect against sepsis has not been reported. In this study, we aimed at evaluation the efficacy of the FX in a model of sepsis mouse.
Methods:
FX was successfully isolated from
Conticribra weissflogii
ND-8 for the first time. The FX was identified by thin-layer chromatography (TLC), high-performance liquid chromatography-mass spectrometry (HPLC-MS), and nuclear magnetic resonance (NMR). Animals were randomly divided into 9 groups, including Sham group (mouse received an intraperitoneal injection of normal saline 1.0 ml/kg), FX-treated (0.1–1.0 ml/kg), Lipopolysaccharide (LPS)-treated (20 mg/kg), FX+LPS-treated (0.1–10.0 mg/kg and 20 mg/kg, respectively), and urinastatin groups (10
4
U/kg). Nuclear factor (NF)-κB activation could be potential treatment for sepsis. NF-κB signaling components were determined by western-blotting. IL-6, IL-1β, TNF-α production, and NF-κB activation were evaluated by ELISA and immunofluorescent staining
in vitro
.
Results:
FX was found to decrease the expression of inflammatory cytokines including IL-6, IL-1β, and TNF-α, in a prophylactic manner in the LPS-induced sepsis mouse model. Meanwhile, FX significantly inhibits phosphorylation of the NF-κB signaling pathway induced by LPS at the cellular level and reduces the nuclear translocation of NF-κB. The IC
50
for suppressing the expression of NF-κB was 11.08 ± 0.78 μM in the THP1-Lucia™ NF-κB cells. Furthermore, FX also inhibits the expression of inflammatory factors in a dose-dependent manner with the IC
50
inhibition of IL-6 production was 2.19 ± 0.70 μM in Raw267.4 macrophage cells. It is likely that the molecules with the ability of targeting NF-κB activation and inflammasome assembly, such as fucoxanthin, are interesting subjects to be used for treating sepsis.
Display omitted
•The conveyor belt and high-speed camera were used to collect the DTD of particles.•The MFR prediction model was established by fitting the mass with image by ANN.•Calculation of MFI ...by CNN combined with error correction.•The test results for glass beads and quartz sand were within the tolerance range.
A machine vision and neural network-based method for the quantitative detection of hopper discharge characteristics based on the discharge time distribution is proposed. Glass beads and quartz sand were utilized as test objects. The prediction model of the relationship between the particle mass and the pixel value of the image was established by an artificial neural network, and the mass flow rate (MFR) was calculated via image prediction. The average relative errors of the predicted MFR for glass beads and quartz sand were found to be −1.31 % and −2.02 %, respectively. Based on the particle marking method, a convolutional neural network was used to classify the image according to whether there were marked particles in the image, and the mass flow index (MFI) was calculated after error correction. The average relative errors of the predicted MFI values for glass beads and quartz sand were found to be −1.43 % and 0.82 %, respectively.
PDF
