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Baculoviruses are insect-infecting pathogens with wide applications as biological pesticides, in vitro protein production vehicles and gene therapy tools. Its cylindrical nucleocapsid, which encapsulates and protects the circular double-stranded viral DNA encoding proteins for viral replication and entry, is formed by the highly conserved major capsid protein VP39. The mechanism for VP39 assembly remains unknown. We use electron cryomicroscopy to determine a 3.2 Å helical reconstruction of an infectious nucleocapsid of Autographa californica multiple nucleopolyhedrovirus, revealing how dimers of VP39 assemble into a 14-stranded helical tube. We show that VP39 comprises a distinct protein fold conserved across baculoviruses, which includes a Zinc finger domain and a stabilizing intra-dimer sling. Analysis of sample polymorphism shows that VP39 assembles in several closely-related helical geometries. This VP39 reconstruction reveals general principles for baculoviral nucleocapsid assembly.Baculoviruses are used as insecticides, gene therapy tools, and protein production vectors. Here, the authors report the structure of the Autographa californica MNPV nucleocapsid and its fold conservation across all baculoviruses. [ABSTRACT FROM AUTHOR]

B-cell lymphoma is the most prevalent type of non-Hodgkin lymphoma, for which the standard treatment regimen includes rituximab combined with CHOP. However, some patients may develop interstitial pneumonitis (IP), which can be caused by various factors; one of the most important factors is Pneumocystis jirovecii. It is crucial to investigate the pathophysiology of IP and implement preventive measures since IP can be fatal for some people. The data were collected from the First Affiliated Hospital, Zhejiang University School of Medicine, where patients with B-cell lymphoma received the R-CHOP/R-CDOP regimen with or without prophylactic use of trimethoprim-sulfamethoxazole (TMP-SMX). Multivariable logistic regression and propensity score matching (PSM) were used to investigate any potential association. Eight hundred thirty-one patients with B-cell lymphoma were classified into two groups: the non-prophylaxis group without TMP-SMX (n=699) and the prophylaxis group with TMP-SMX (n = 132). IP occurred in 66 patients (9.4%, all in the non-prophylaxis group), with an onset median of three cycles of chemotherapy. Multiple logistic regression analysis demonstrated that IP incidence was associated with pegylated liposome doxorubicin (OR=3.29, 95% CI 1.84–5.90, P<0.001). After utilizing a 1:1 matching algorithm for PSM, 90 patients from each group were obtained. There was a statistical difference between the two cohorts in the IP incidence (non-prophylaxis 12.2% vs prophylaxis 0.0%, P <0.001). The prophylactic use of TMP-SMX could prevent the occurrence of IP whose risk factor was pegylated liposome doxorubicin after chemotherapy for B-cell lymphoma. [ABSTRACT FROM AUTHOR]

Purpose: Sacha inchi meal (SIM, Plukenetia volubilis L.) is a by-product of Sacha inchi oil production, which was mainly used as the aquatic animal feed ingredient. The purpose of this study was to investigate the lipid-lowering activity of SIM hydrolysates. Methods: In this study, SIM protein was hydrolyzed with six proteases, and the lipid-lowering activity was evaluated. Results: The results showed that the half inhibition concentration IC50 values of pepsin hydrolysate, papain hydrolysate (SPa), trypsin hydrolysate (STr), and bromelain hydrolysate on pancreatic lipase were 34.96, 25.40, 24.49, 22.90 μg/mL, respectively. In addition, the hydrolysates SPa and STr can significantly reduce fat accumulation in HepG2 cells, at high concentration, the triglyceride content in the cells was only 0.07 ± 0.01, and 0.23 ± 0.02 mmol/g protein, respectively, which were even lower than that of positive drug Orlistat (0.89 ± 0.01 mmol/g protein). Conclusion: In a word, SIM protein hydrolysates had potent hypolipidemic activity, which is useful for valorization of Sacha inchi processing waste. [ABSTRACT FROM AUTHOR]

Bacillus coagulans has a potential role in improving intestinal injury. However, the specific mechanism is still unclear. In this study, the protective effect of B. coagulans MZY531 on intestinal mucosa injury in cyclophosphamide (CYP)-induced immunosuppressed mice were investigated. The results indicated that the immune organ (thymus and spleen) indices of B. coagulans MZY531 treatment groups were significantly increased compared to the CYP group. B. coagulans MZY531 administration promotes the expression of immune proteins (IgA, IgE, IgG, and IgM). B. coagulans MZY531 could upregulate the ileum levels of IFN-γ, IL-2, IL-4, and IL-10 in immunosuppressed mice. Moreover, B. coagulans MZY531 restores the villus height and crypt depth of the jejunum and alleviates injury of intestinal endothelial cells caused by CYP. Furthermore, the western blotting results showed that B. coagulans MZY531 ameliorated CYP-induced intestinal mucosal injury and inflammatory via up-regulates the ZO-1 pathway and down-regulates the expression of the TLR4/MyD88/NF-κB pathway. After treatment with B. coagulans MZY531, the relative abundance of Firmicutes phylum was dramatically increased, as well as the genera of Prevotella and Bifidobacterium, and reducing harmful bacteria. These findings suggested that B. coagulans MZY531 has a potential immunomodulatory activity on chemotherapy-induced immunosuppression. [ABSTRACT FROM AUTHOR]

The transport of the CagA effector into gastric epithelial cells by the Cag Type IV secretion system (Cag T4SS) of Helicobacter pylori (H. pylori) is critical for pathogenesis. CagA is recruited to Cag T4SS by the Cagβ ATPase. CagZ, a unique protein in H. pylori, regulates Cagβ-mediated CagA transport, but the underlying mechanisms remain unclear. Here we report the crystal structure of the cytosolic region of Cagβ, showing a typical ring-like hexameric assembly. The central channel of the ring is narrow, suggesting that CagA must unfold for transport through the channel. Our structure of CagZ in complex with the all-alpha domain (AAD) of Cagβ shows that CagZ adopts an overall U-shape and tightly embraces Cagβ. This binding mode of CagZ is incompatible with the formation of the Cagβ hexamer essential for the ATPase activity. CagZ therefore inhibits Cagβ by trapping it in the monomeric state. Based on these findings, we propose a refined model for the transport of CagA by Cagβ.Cagβ is an ATPase in the H. pylori CagType4 secretion system essential for delivering the CagA effector to host cells. Here, authors present crystal structures of hexameric apo-Cagβ and Cagβ trapped in the monomeric state by its regulator CagZ, uncovering the regulatory mechanisms of Cagβ. [ABSTRACT FROM AUTHOR]

Purpose: Squid processing by-product is a kind of industrial waste, which is usually treated as low-value filler of fertilizer or animal feed. Squid processing by-product hydrolysate was reported to have angiotensin-converting enzyme (ACE) inhibitory activity. The purpose of this study was to investigate ACE and renin inhibitory activity of fermentation products of squid processing by-product. Methods: Active hydrolysate was prepared from squid processing by-product fermented by Bacillus natto, the process conditions were optimized by response surface analysis. Results: The effects of various factors on ACE inhibition rate and polypeptide content were as follows: B (fermentation temperature) > C (inoculation amount) > D (liquid to solid ratio) > A (fermentation time). The optimal fermentation conditions were as follows: 37.5 h, 42.1 ℃, 6% of inoculation, and 22.7:1 of liquid (fermentation broth) to solid (squid processing by-product powder) ratio. Under these conditions, the ACE inhibition rate and peptide content of fermentation broth were 82.22% and 208.18 mg/g, respectively. Subsequently, the broth was ultrafiltrated, and the filtrate (< 1 kDa) was found to have best ACE and renin inhibition activities, reaching 86.50 ± 1.84% and 81.09 ± 1.23% at 1 mg/mL, respectively, compared with other filtrates of the broth; However, after simulated gastrointestinal digestion, these activities decreased to 48.24 ± 1.18% and 49.37 ± 1.16%, respectively. The half inhibition concentration (IC50) values of ACE and renin inhibition were determined as 1.01 ± 0.08 mg/mL and 1.15 ± 0.09 mg/mL, respectively. Conclusions: Taken together, the present data suggest that the fermented squid processing by-product is a potential source of ACE and renin inhibitory compounds. Dual inhibitory hydrolysate by fermentation of squid processing by-product [ABSTRACT FROM AUTHOR]

Stimulator of interferon genes (STING) is an adaptor protein in innate immunity against DNA viruses or bacteria1–5. STING-mediated immunity could be exploited in the development of vaccines or cancer immunotherapies. STING is a transmembrane dimeric protein that is located in the endoplasmic reticulum or in the Golgi apparatus. STING is activated by the binding of its cytoplasmic ligand-binding domain to cyclic dinucleotides that are produced by the DNA sensor cyclic GMP-AMP (cGAMP) synthase or by invading bacteria1,6,7. Cyclic dinucleotides induce a conformational change in the STING ligand-binding domain, which leads to a high-order oligomerization of STING that is essential for triggering the downstream signalling pathways8,9. However, the cGAMP-induced STING oligomers tend to dissociate in solution and have not been resolved to high resolution, which limits our understanding of the activation mechanism. Here we show that a small-molecule agonist, compound 53 (C53)10, promotes the oligomerization and activation of human STING through a mechanism orthogonal to that of cGAMP. We determined a cryo-electron microscopy structure of STING bound to both C53 and cGAMP, revealing a stable oligomer that is formed by side-by-side packing and has a curled overall shape. Notably, C53 binds to a cryptic pocket in the STING transmembrane domain, between the two subunits of the STING dimer. This binding triggers outward shifts of transmembrane helices in the dimer, and induces inter-dimer interactions between these helices to mediate the formation of the high-order oligomer. Our functional analyses show that cGAMP and C53 together induce stronger activation of STING than either ligand alone.The cryo-electron microscopy structure of human STING bound to both cyclic GMP-AMP and the small-molecule agonist C53 reveals an agonist-binding site in the STING transmembrane domain, and provides insight into the oligomerization and activation of STING. [ABSTRACT FROM AUTHOR]

This article mainly focuses on the most common types of high-speed railways malfunctions in overhead contact systems, namely, unstressed droppers, foreign-body invasions, and pole number-plate malfunctions, to establish a deep-network detection model. By fusing the feature maps of the shallow and deep layers in the pretraining network, global and local features of the malfunction area are combined to enhance the network's ability of identifying small objects. Further, in order to share the fully connected layers of the pretraining network and reduce the complexity of the model, Tucker tensor decomposition is used to extract features from the fused-feature map. The operation greatly reduces training time. Through the detection of images collected on the Lanxin railway line, experiments result show that the proposed multiview Faster R-CNN based on tensor decomposition had lower miss probability and higher detection accuracy for the three types faults. Compared with object-detection methods YOLOv3, SSD, and the original Faster R-CNN, the average miss probability of the improved Faster R-CNN model in this paper is decreased by 37.83%, 51.27%, and 43.79%, respectively, and average detection accuracy is increased by 3.6%, 9.75%, and 5.9%, respectively. [ABSTRACT FROM AUTHOR]

Squid processing by-product contains unutilized abundant proteins. In this study, 6 proteases (pepsin, protamex, trypsin, neutral protease, alkaline protease, and papain) were firstly employed to hydrolyze the squid processing by-product protein. The neutral protease-digested hydrolysate was found to have the most promising ACE (angiotensin-converting enzyme) inhibitory activity. Based on Box-Behnken design, the optimal hydrolysis process was determined to be: 52.4 ℃ of temperature, 5.7 h of time, pH 7.1, and 8151 U/g of enzyme. Under these conditions, the ACE inhibition rate and polypeptide content of the hydrolysate were 84.26% and 229.09 mg/g, respectively. Subsequently, ultrafiltration was performed, and the ACE and renin inhibitory activities of the filtrate (< 1 kDa) were the highest, reaching 87.48 ± 1.76% and 69.72 ± 1.16%, with IC50 values of 1.34 ± 0.12 mg/mL and 1.47 ± 0.06 mg/mL, respectively. However, these activities decreased to 35.15 ± 1.31% and 43.17% ± 1.42%, respectively, after digestion by simulated gastrointestinal juice. Nevertheless, this is the first report representing the neutral protease-digested hydrolysate of squid processing by-product as a potential source of both ACE and renin inhibitors. [ABSTRACT FROM AUTHOR]

Underwater target detection and classification based on sonar images is a challenging task because of the complex underwater environment. In recent years, deep learning technology has effectively improved the detection accuracy of underwater targets compared to traditional sonar image target detection methods, which have a low accuracy and poor robustness. However, deep learning algorithms for sonar image target detection have fewer training samples and a low detection speed. To solve these problems, an improved YOLOv4 based sonar target detection and classification algorithm is proposed in this paper. First, the feature extraction network CSPDarknet-53 in YOLOv4 is improved to reduce both the model parameters and the network depth. Second, the PANet feature enhancement module in the YOLOv4 model is replaced by the adaptive spatial feature fusion module (ASFF) to obtain a better feature fusion effect. In addition, the number of fusion feature layers is increased to improve the receptive field and detection accuracy. Furthermore, this paper uses the k-means++ algorithm to cluster the sonar image dataset to obtain the appropriate size and number of anchor boxes for model training. The experimental results show that the proposed method has better performance in detection accuracy and detection speed compared to YOLOv4 and YOLOv4-tiny. [ABSTRACT FROM AUTHOR]

Objective: Dickkopf-1 (Dkk-1), a regulatory molecule of the Wnt pathway, is elevated and leads to bone resorption in patients with RA. This study is aimed to investigate the contribution of Dkk-1 to synovial inflammation and synovial fibroblast-mediated angiogenesis in RA. Methods: The expression of Dkk-1 in RA synovial fibroblasts (RASF) and osteoarthritis synovial fibroblasts (OASF) was detected by real-time PCR and ELISA, respectively. RASF were stimulated with different pro-inflammatory factors. The expression of angiogenic factors, pro-inflammatory cytokines, and MMPs in RASF was analyzed by real-time PCR when Dkk-1 was inhibited or overexpressed. Meanwhile, the concentrations of MCP-1, IL-6, IL-8, and MMP-3 in the cell culture supernatant were assessed by ELISA. The effects of Dkk-1 on the MAPK signaling pathway were evaluated by western blot. Matrigel tube formation assay was employed to reveal the direct and indirect effects of Dkk-1 on synovial angiogenesis. Results: Dkk-1 expression was elevated in synovial fluids and synovial fibroblasts of RA patients. Treatment with various pro-inflammatory cytokines significantly promoted DKK-1 expression in RASF. The production of potent angiogenic factors, pro-inflammatory cytokines, and MMPs in RASF was elevated, whereas the reverse results were found in the inhibitor groups. Silenced Dkk-1expression in RASF dampened capillary tube organization in both direct and indirect manners, resulting in restrained ERK, JNK, and p38 signaling pathway activation. Conclusion: We concluded that Dkk-1 exacerbated the inflammation, cartilage erosion, and angiogenesis mediated by synovial fibroblasts in RA. Modulation of DKK-1 expression may facilitate development of novel strategies to control RA. Key points • Dkk-1 expression was elevated in synovial fluids and synovial fibroblasts of RA patients. • Treatment with various pro-inflammatory cytokines significantly promoted DKK-1 expression. • Silenced Dkk-1expression in RASF dampened capillary tube organization. [ABSTRACT FROM AUTHOR]

The c-MET receptor is a receptor tyrosine kinase (RTK) that plays essential roles in normal cell development and motility. Aberrant activation of c-MET can lead to both tumors growth and metastatic progression of cancer cells. C-MET can be activated by either hepatocyte growth factor (HGF), or its natural isoform NK1. Here, we report the cryo-EM structures of c-MET/HGF and c-MET/NK1 complexes in the active state. The c-MET/HGF complex structure reveals that, by utilizing two distinct interfaces, one HGF molecule is sufficient to induce a specific dimerization mode of c-MET for receptor activation. The binding of heparin as well as a second HGF to the 2:1 c-MET:HGF complex further stabilize this active conformation. Distinct to HGF, NK1 forms a stable dimer, and bridges two c-METs in a symmetrical manner for activation. Collectively, our studies provide structural insights into the activation mechanisms of c-MET, and reveal how two isoforms of the same ligand use dramatically different mechanisms to activate the receptor. Activation of c-MET receptor tyrosine kinase involves hepatocyte growth factor (HGF) and glycosaminoglycans, but the molecular mechanism is still under debate. Here, the authors present cryoEM structures of c-MET bound to two HGF splice variants and heparin, revealing the structural basis for c-MET activation. [ABSTRACT FROM AUTHOR]

Secreted class 3 semaphorins (Sema3s) form tripartite complexes with the plexin receptor and neuropilin coreceptor, which are both transmembrane proteins that together mediate semaphorin signal for neuronal axon guidance and other processes. Despite extensive investigations, the overall architecture of and the molecular interactions in the Sema3/plexin/neuropilin complex are incompletely understood. Here we present the cryo-EM structure of a near intact extracellular region complex of Sema3A, PlexinA4 and Neuropilin 1 (Nrp1) at 3.7 Å resolution. The structure shows a large symmetric 2:2:2 assembly in which each subunit makes multiple interactions with others. The two PlexinA4 molecules in the complex do not interact directly, but their membrane proximal regions are close to each other and poised to promote the formation of the intracellular active dimer for signaling. The structure reveals a previously unknown interface between the a2b1b2 module in Nrp1 and the Sema domain of Sema3A. This interaction places the a2b1b2 module at the top of the complex, far away from the plasma membrane where the transmembrane regions of Nrp1 and PlexinA4 embed. As a result, the region following the a2b1b2 module in Nrp1 must span a large distance to allow the connection to the transmembrane region, suggesting an essential role for the long non-conserved linkers and the MAM domain in neuropilin in the semaphorin/plexin/neuropilin complex. Secreted class 3 semaphorins (Sema3s) form tripartite complexes with a plexin receptor and neuropilin co-receptor to transduce signals for neuronal axon guidance and other processes. Here, the authors present the cryo-EM structure of the extracellular Sema3A/PlexinA4/Neuropilin1 complex that provides further insights into the interactions among semaphorin, plexin and neuropilin and reveals long flexible linkers in semaphorin and neuropilin that are important for complex formation. [ABSTRACT FROM AUTHOR]

Autophagy, a process of degradation that occurs via the lysosomal pathway, has an essential role in multiple aspects of immunity, including immune system development, regulation of innate and adaptive immune and inflammatory responses, selective degradation of intracellular microorganisms, and host protection against infectious diseases1,2. Autophagy is known to be induced by stimuli such as nutrient deprivation and suppression of mTOR, but little is known about how autophagosomal biogenesis is initiated in mammalian cells in response to viral infection. Here, using genome-wide short interfering RNA screens, we find that the endosomal protein sorting nexin 5 (SNX5)3,4 is essential for virus-induced, but not for basal, stress- or endosome-induced, autophagy. We show that SNX5 deletion increases cellular susceptibility to viral infection in vitro, and that Snx5 knockout in mice enhances lethality after infection with several human viruses. Mechanistically, SNX5 interacts with beclin 1 and ATG14-containing class III phosphatidylinositol-3-kinase (PI3KC3) complex 1 (PI3KC3-C1), increases the lipid kinase activity of purified PI3KC3-C1, and is required for endosomal generation of phosphatidylinositol-3-phosphate (PtdIns(3)P) and recruitment of the PtdIns(3)P-binding protein WIPI2 to virion-containing endosomes. These findings identify a context- and organelle-specific mechanism—SNX5-dependent PI3KC3-C1 activation at endosomes—for initiation of autophagy during viral infection. Genome-wide siRNA screens identify an essential function for sorting nexin 5 in virus-induced autophagy and immunity mediated via class III phosphatidylinositol-3-kinase complex 1. [ABSTRACT FROM AUTHOR]

Currently, no specific drug and vaccine are available for the new coronavirus SARS-CoV-2, and nutritional supplementation should be helpful. This study tried to provide reference for protein supplementation. Specifically, in silico method was employed to simulate protein degradation by gastrointestinal enzymes and to produce a large number of active peptides, then, the binding ability of these peptides to SARS-CoV-2 spike protein receptor-binding domain (RBD) was evaluated. The results showed that wheat-derived alpha/beta-gliadin, oat-derived avenin, and ribulose bisphosphate carboxylase small chain of different origin could be good protein source in generating potent binders to SARS-CoV-2 spike RBD. In addition, some high-affinity oligopeptides (such as PISCR, VQVVN, PQQQF, etc.) were identified as potential binders of SARS-CoV-2 spike RBD. In summary, a number of plant proteins could be helpful for COVID-19 patients when supplemented with these proteins, the identified oligopeptides could be used as lead compound to design potential entry inhibitors against SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Plexins are receptors for semaphorins that transduce signals for regulating neuronal development and other processes. Plexins are single-pass transmembrane proteins with multiple domains in both the extracellular and intracellular regions. Semaphorin activates plexin by binding to its extracellular N-terminal Sema domain, inducing the active dimer of the plexin intracellular region. The mechanism underlying this activation process of plexin is incompletely understood. We present cryo-electron microscopic structure of full-length human PlexinC1 in complex with the viral semaphorin mimic A39R. The structure shows that A39R induces a specific dimer of PlexinC1 where the membrane-proximal domains from the two PlexinC1 protomers are placed close to each other, poised to promote the active dimer of the intracellular region. This configuration is imposed by a distinct conformation of the PlexinC1 extracellular region, stabilized by inter-domain interactions among the Sema and membrane-proximal domains. Our mutational analyses support the critical role of this conformation in PlexinC1 activation. Plexins are the receptors for the guidance molecules semaphorins and regulate immunity and the development of the nervous and cardiovascular systems. Here authors present a structure of full-length human PlexinC1 in complex with its ligand A39R, which reveals how inter-domain interactions couple extracellular ligand binding to receptor activation and signaling. [ABSTRACT FROM AUTHOR]

Objectives: To detect the serum free fatty acid (FFA) concentration in patients with primary gouty arthritis (GA) and to explore the correlation between FFA and gout flare. Method: Sixty patients with acute GA, 60 patients with GA remission, 60 patients with asymptomatic hyperuricemia (HUA), and 60 normal controls were enrolled in this study. Serum FFA concentration was detected by enzymatic determination in four groups, and the relationship between serum FFA, serum urate (SU), and other clinical and laboratory parameters was analyzed. Results: (1) Serum FFA concentration was significantly higher in the acute GA than in the GA remission, the asymptomatic HUA, and the normal control (H = 72.191, P < 0.001). (2) There were no significant difference in serum triglyceride and low-density lipoprotein cholesterol (LDL-C) concentration between the acute GA, the GA remission, the asymptomatic HUA, and the normal control group. Conclusions: FFA may be involved in the acute attack of gout in conditions of monosodium urate crystal deposition in the joints. Triglyceride and LDL-C may not be involved in the acute attack of gout. FFA may be used as an indicator to monitor the status of GA in clinical. Key Points • Lin Pei and Linfeng Xie designed the randomized controlled trial and were responsible for the development of the protocol. [ABSTRACT FROM AUTHOR]

The invasion of mammalian cytoplasm by microbial DNA from infectious pathogens or by self DNA from the nucleus or mitochondria represents a danger signal that alerts the host immune system1. Cyclic GMP-AMP synthase (cGAS) is a sensor of cytoplasmic DNA that activates the type-I interferon pathway2. On binding to DNA, cGAS is activated to catalyse the synthesis of cyclic GMP-AMP (cGAMP) from GTP and ATP3. cGAMP functions as a second messenger that binds to and activates stimulator of interferon genes (STING)3-9. STING then recruits and activates tank-binding kinase 1 (TBK1), which phosphorylates STING and the transcription factor IRF3 to induce type-I interferons and other cytokines10,11. However, how cGAMP-bound STING activates TBK1 and IRF3 is not understood. Here we present the cryo-electron microscopy structure of human TBK1 in complex with cGAMP-bound, full-length chicken STING. The structure reveals that the C-terminal tail of STING adopts a β-strand-like conformation and inserts into a groove between the kinase domain of one TBK1 subunit and the scaffold and dimerization domain of the second subunit in the TBK1 dimer. In this binding mode, the phosphorylation site Ser366 in the STING tail cannot reach the kinase-domain active site of bound TBK1, which suggests that STING phosphorylation by TBK1 requires the oligomerization of both proteins. Mutational analyses validate the interaction mode between TBK1 and STING and support a model in which high-order oligomerization of STING and TBK1, induced by cGAMP, leads to STING phosphorylation by TBK1. The cryo-electron microscopy structure of human TBK1 in complex with cyclic GMP-AMP-bound chicken STING reveals a binding mode that suggests that STING phosphorylation by TBK1 requires oligomerization of both proteins. [ABSTRACT FROM AUTHOR]

Infections by pathogens that contain DNA trigger the production of type-I interferons and inflammatory cytokines through cyclic GMP-AMP synthase, which produces 2′3′-cyclic GMP-AMP (cGAMP) that binds to and activates stimulator of interferon genes (STING; also known as TMEM173, MITA, ERIS and MPYS)1-8. STING is an endoplasmic-reticulum membrane protein that contains four transmembrane helices followed by a cytoplasmic ligand-binding and signalling domain9-13. The cytoplasmic domain of STING forms a dimer, which undergoes a conformational change upon binding to cGAMP9,14. However, it remains unclear how this conformational change leads to STING activation. Here we present cryo-electron microscopy structures of full-length STING from human and chicken in the inactive dimeric state (about 80 kDa in size), as well as cGAMP-bound chicken STING in both the dimeric and tetrameric states. The structures show that the transmembrane and cytoplasmic regions interact to form an integrated, domain-swapped dimeric assembly. Closure of the ligand-binding domain, induced by cGAMP, leads to a 180° rotation of the ligand-binding domain relative to the transmembrane domain. This rotation is coupled to a conformational change in a loop on the side of the ligand-binding-domain dimer, which leads to the formation of the STING tetramer and higher-order oligomers through side-by-side packing. This model of STING oligomerization and activation is supported by our structure-based mutational analyses. Cryo-electron microscopy structures of full-length STING show that cyclic GMP-AMP induces a half-turn rotation of the ligand-binding domain relative to the transmembrane domain, forming a tetramer and higher-order oligomers for signalling. [ABSTRACT FROM AUTHOR]

Dam crack detection is necessary to ensure the safety of dams. However, traditional detection methods always perform poorly, with a low detection rate and high false alarm rate, due to the complex underwater environment. In this paper, a novel automatic dam crack detection algorithm (CrackLG) is proposed based on local-global clustering analysis that can find cracks on dam surfaces accurately and quickly using images as well as reduce human subjectivity. First, an image shot of an underwater dam surface is divided into non-overlapping image blocks after pre-processing. Then, image blocks containing crack pixels are identified by local clustering analysis. Second, the image is binarized by adaptive bi-level thresholding based on the local gray intensity. Meanwhile, some noise is removed based on the computed optimal threshold. After extracting global 3-D features, final crack regions are obtained by global clustering analysis. The advantage of CrackLG is that the threshold for realizing image binarization is self-adaptive. Additionally, it can automatically perform crack detection without human supervision. The simulation and comparison show that the proposed CrackLG method is more effective for underwater dam crack detection. [ABSTRACT FROM AUTHOR]

This paper proposes a new virus spreading model, susceptible-infected-susceptible-recovered-susceptible, which is based on partial immunization and immune invalidity in a complex network. On the basis of mean-field theory, the epidemic dynamics behavior of this model in a uniform network and a scale-free network is studied. After modifying the formula for the effective spread rate, we obtain the theoretical result that the coexistence of partial immunization and immune failure does not affect the network spread threshold. At the same time, the experimental results show that the existence of the above two conditions greatly increases the spread of the virus and extends the diffusion range. The study also found that in the scale-free network, peak viral infection occurs at the beginning of the spreading process, and after the immunization strategy is applied, the early infection peak is effectively curbed. [ABSTRACT FROM AUTHOR]

In this study, the whole protein of Arthrospira (Spirulina) platensis was extracted and hydrolyzed with trypsin. Screening process for new peptides was driven by 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity assay, and a hexapeptide with sequence of GMCCSR was identified. Its anti-oxidant activity was measured based on ABTS, 1,1’-diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing ability of plasma (FRAP) assays. Hemolysis inhibition on human erythrocytes and collagen-stimulating activities on human skin fibroblasts (HSFs) were investigated. Results showed that its radical scavenging effect could compete with ascorbic acid. Intracellular assays revealed the reduction of reactive oxygen species (ROS) and malondialdehyde (MDA) contents and the increase in activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in erythrocytes pretreated with hexapeptide, demonstrating that the peptide could protect erythrocytes from lipid peroxidation and protein oxidation. Moreover, results from HSFs showed that it could promote proliferation and collagen production of HSFs pro-damaged by UVB. These results suggest the potential of the hexapeptide in food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

In this study, proteins were extracted from the red macroalga Pyropia haitanensis and hydrolyzed with pepsin and papain. Gel filtration chromatography was performed to separate hydrolysates. Three fractions were obtained from papain-digested hydrolysates, which showed anti-proliferation effects on human breast cancer cells (MCF-7), human liver cancer cells (HepG-2), and human lung cancer cells (A549), with IC values of 59.09-272.67 μg mL. Furthermore, a new peptide QTDDNHSNVLWAGFSR was identified, which had the best inhibition on HepG-2 cancer cells (61.36%), but low inhibition on human normal liver cells LO-2 (22.81%), at 500 μg mL. This is the first time that anti-proliferative peptides originating from protein hydrolysates of P. haitanensis were isolated and characterized. [ABSTRACT FROM AUTHOR]

In this study, Arthrospira platensis proteins were hydrolyzed using sequential digestion with alcalase/papain. Gel filtration chromatography was used to separate hydrolysates and five fractions D1-D5 were obtained. D1 showed the strongest antitumor effects on MCF-7 and HepG-2 cells, with the IC values of <31.25 and 49.36 μg mL, respectively. Subsequently, three small peptides with antitumor activities, including AGGASLLLLR, LAGHVGVR, and KFLVLCLR, were identified. The truncated peptide LCLR exhibited better activity than its parent peptide KFLVLCLR, with the inhibition rate of >60 % on MCF-7 and HepG-2 cells, but little cytotoxicity on L-O2 cells (∼6 %), at 500 μg mL. Moreover, D1 was confirmed to inhibit solid tumor growth in HepG-2-bearing nude mice, with the best inhibition achieved at day 11, up to 39.75 % at the dosage of 200 mg kg day. Taken together, the identified peptides possessed potent antitumor activities but low cytotoxicity on normal cells and could be used as nutraceuticals and pharmaceuticals. [ABSTRACT FROM AUTHOR]

In order to evaluate the exposure risk of lead and cadmium in seafood for coastal residents in the coastline of the South China, representative seafood such as sea fish, crustaceans and molluscs were collected and used as research samples in many sampling points. By determining lead and cadmium content in sample using graphite furnace atomic absorption spectrometry, we carried out a safety evaluation of lead and cadmium contamination of seafood by single factor pollution index method. By calculating lead, cadmium intake of the coastal residents eating seafood, their exposure risk of lead, cadmium was assessed. It was found that, firstly, the content of lead and cadmium in mollusks was both higher than sea fish and crustaceans in the same waters. Secondly, the lead and cadmium pollution in seafood near the mouth of Pearl River was the most serious. Thirdly, lead and cadmium intakes of the coastal population eating seafood were at a basic level of security, but there were certain risks on the males less than 17 years old eating molluscs in Shenzhen Bay. [ABSTRACT FROM AUTHOR]

Aptamers are short and functional single-stranded oligonucleotide sequences selected from systematic evolution of ligands by exponential enrichment (SELEX) process, which have the capacity to recognize various classes of target molecules with high affinity and specificity. Various analytical aptamers acquired by SELEX are widely used in many research fields, such as medicine, biology, and chemistry. However, the application of this innovative and emerging technology to food safety is just in infant stage. Food safety plays a very important role in our daily lives because varieties of poisonous and harmful substances in food affect human health. Aptamer technique is promising, which can overcome many disadvantages of existing detection methods in food safety, such as long detection time, low sensitivity, difficult, and expensive antibody preparation. This review provides an overview of various aptamer screening technologies and summarizes the recent applications of aptamers in food safety, and future prospects are also discussed. [ABSTRACT FROM AUTHOR]

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease that lacks sensitive and specific diagnostic methods. The aim of this study was to identify potential biomarkers specific for pSS and to establish a diagnostic model. Serum samples from patients with pSS, disease controls (DC, patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA)), and healthy controls (HC)) were randomly divided into a training set (35 pSS, 50 DC, and 26 HC) and a testing set (25 pSS, 50 DC, and 25 HC). Weak cationic exchange (WCX) magnetic beads were used to differentially capture serum proteins prior to proteomic analysis. Proteomic mass spectra were generated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). One hundred differential M/Z peaks associated with pSS were identified, and the m/z peaks at 8,133.85, 11,972.8, 2,220.81, and 4,837.66 were used to establish a diagnostic model for pSS. This diagnostic model was able to distinguish pSS from non-pSS controls with a sensitivity of 77.1 % and a specificity of 85.5 %, and its efficacy was confirmed in our blinded testing set with good sensitivity and specificity of 95.5 and 88 %, respectively. The results indicated that the proteomic fingerprinting model was effective in the diagnosis of pSS. [ABSTRACT FROM AUTHOR]

Lung cancer is still difficult to treat by current chemotherapeutic procedures. We recently found that MVL, an anti-HIV lectin from blue-green algae Microcystis viridis, also has antitumor activity. The objective of this study was to investigate apoptosis-inducing activity of recombinant MVL (R-MVL) and proteomic changes in A549 cells, and to identify the molecular pathways responsible for the anti-cancer action of R-MVL. We found that R-MVL induces A549 cells apoptosis in a dose-dependent manner by using MTT assay, fluorescent microscope (FM) and flow cytometry (FCM), and the IC50 was calculated to be 24.12 μg/ml. Subsequently, 7 altered proteins in R-MVL-treated A549 cells were identified, including upregulated aldehyde dehydrogenase 1 and β-actin, and five downregulated proteins: heat shock protein 90, heat shock 60, plastin 3, tropomyosin 3, and β-tubulin. Further bioinformatics analysis predicted the potential pathways for R-MVL to induce apoptosis of A549 cells. In conclusion, this is the first report to investigate anti-cancer activity of R-MVL and its mechanism of action by proteomics analysis. Our observations provide potential therapeutic targets for lung cancer inhibitor intervention and implicated the development of novel anti-cancer therapeutic strategies. [ABSTRACT FROM AUTHOR]

C-Phycocyanin is a natural blue pigment with many commercial applications in foods, cosmetics, and medicines. In this paper we describe the extraction and purification of C-phycocyanin from the cyanobacterium Spirulina platensis. The procedure is based on adsorption of impurities with chitosan and activated charcoal then one-step ion-exchange chromatography. The dry algal powder was soaked in potassium phosphate buffer for 2 h to furnish crude phycocyanin extract of purity 0.93. The crude extract was then treated with chitosan and activated charcoal for 5 min, which increased the purity to 2.78. After chromatography on DEAE Sephadex A-25, the purity of phycocyanin was improved to 4.3. The identity of the purified phycocyanin was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis and by spectroscopic measurements (UV-visible spectrophotometry and spectrofluorimetry). Compared with conventional methods, this method was simple, inexpensive, and time-saving. [ABSTRACT FROM AUTHOR]

Microcystis viridis lectin (MVL), a sugar-binding protein originally isolated from freshwater blue-green algae Microcystis viridis, has been reported to have potent anti-HIV activity. In this paper, we described the expression and purification of recombinant-MVL (R-MVL) gene in E. coli. The results demonstrated that the R-MVL in shake flask cultures was primarily expressed either in the form of inclusion bodies at 37°C or in the soluble fraction at 23 °C. Secondly, a one-step purification based on nickel-affinity chromatography was employed and 15 mg of highly purified (>95%) R-MVL from 1 l of cell cultures was yielded. The purified R-MVL was then subjected to MALDI-TOF-MS analysis for protein identification. In conclusion, for the first time, the R-MVL was successfully cloned and expressed in E. coli, which is useful for further study and large-scale cost-effective production of MVL protein. [ABSTRACT FROM AUTHOR]

The fast growing unicellular green microalgae Chlorella protothecoides has attracted interest as a promising organism for commercial production of a high-value carotenoid, lutein, by heterotrophic fermentation. Effects of two oxidant-forming reactive oxygen species (ROS) on the biomass concentration, and yield and content of lutein in batch culture of heterotrophic Chlorella protothecoides were investigated in this study. The addition of 0.1 mmol/L H2O2 and 0.01 mmol/L NaClO plus 0.5 mmol/L Fe2+ to the culture led to the generation of ·OH and enhanced the lutein content from 1.75 to 1.90 and 1.95 mg/g, respectively. The lutein content further increased to 1.98 mg/g when 0.01 mmol/L H2O2 and 0.5 mmol/L NaClO were added to generate 1O2. The maximum yield of lutein (28.5, 29.8 and 31.4 mg/L) and a high biomass concentration (15.0, 15.3 and 15.9 g/L) were also achieved through the above treatments. The results indicated that 1O2 could promote lutein formation and enhance lutein production in heterotrophic Chlorella protothecoides. Moreover, 1O2 produced from the reaction of H2O2 and NaClO was more effective in enhancing lutein production and reducing biomass loss than ·OH from the reaction of H2O2 or NaClO plus Fe2+. [ABSTRACT FROM AUTHOR]

Recent studies have highlighted the structural requirements for T cell costimulation and have revealed unusual modes of dimerization for the cytolytic T lymphocyte-associated antigen 4 (CTLA-4) costimulatory receptor and its B7 ligands. These distinctive quaternary structures potentially endow both receptor and ligand with bivalent binding properties, which suggests a number of mechanistic features relevant to signaling. These include the potential to form a highly ordered, alternating network of CTLA-4 and B7 homodimers that may represent the organization of these molecules and their associated signaling partners within the immunological synapse. Primary sequence and structural considerations suggest that some aspects of the organizational and mechanistic features associated with the CTLA-4-B7 complexes may extend to other members of the costimulatory receptor-ligand family. An examination of the signaling mechanisms within the costimulatory receptor-ligand family provides an excellent framework to consider the general principles that are relevant to cell surface receptor-mediated signaling events. [ABSTRACT FROM AUTHOR]