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In order to clarify the effect of the non-catalytic carbohydrate-binding module (CBM) and F5/8 type C domains on the enzymatic properties of AlgL7, an alginate lyase from Microbulbifer sp. ALW1, the full-length enzyme AlgL7 and two truncated enzymes: CD1 (catalytic domain) and CD2 (containing F5/8 type C domain and catalytic domain) were constructed and characterized. The results showed that the truncated enzyme CD2 exhibited higher specific activity, thermostability, Michaelis constant (Km), and maximum reaction velocity (Vmax) compared to the full-length AlgL7, indicating that the CBM domain played an important role in maintaining the substrate affinity of the enzyme, but reduced the catalytic activity, thermostability, and Vmax value the enzyme. Compared to the truncated enzyme CD1, CD2 exhibited higher specific activity, optimal reaction temperature, thermostability, Vmax, and Km, indicating that the F5/8 type C domain contributed to improve the enzymatic activity, optimum reaction temperature, thermostability, and Vmax, but reduced the substrate affinity of the enzyme. Using sodium alginate as the substrate, the specific activity of CD2 was 183.9 U/mg. The optimal reaction temperature and pH were 40 ℃ and 7.0, respectively. The Km and Vmax were 39.80 mg/mL and 2 000 U/mg, respectively. The major enzymatic hydrolysates were disaccharides and trisaccharides. This study promotes the understanding of the structure-activity relationship between the non-catalytic domains and the properties of alginate lyase, and lays a theoretical basis for using the non-catalytic domains to improve the catalytic properties of alginate lysate.

In this study, the total sugar, protein, 3,6-anhydro galactose and sulfate contents, apparent molecular mass and monosaccharide composition of porphyran isolated from Porphyra yezoensis were analyzed. The pro-angiogenic activity and underlying mechanism of porphyran were further investigated using human umbilical vein endothelial cells (HUVECs) as an in vitro angiogenesis model. The effect of porphyran on the cell viability of HUVECs was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell adhesion and migration capacity were evaluated using cell adhesion and wound healing assays. The number of lumens formed by HUVECs was analyzed using in vitro tube formation assay. The expression levels of E-cadherin and N-cadherin in HUVECs were analyzed by Western Blotting, and the pro-angiogenic mechanism of porphyran in HUVECs was explored using specific inhibitors of mitogen-activated protein kinases (MAPKs) and vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitors. The results showed that porphyran contained (77.48 ± 2.62)% total sugar, (3.24 ± 0.58)% protein, and (20.30 ± 1.06)% 3,6-anhydrogalactose as well as (20.78 ± 3.31)% sulfate groups. The apparent molecular mass of porphyran was 39.81 kDa. Porphyran was mainly composed of galactose, 3,6-anhydrogalactose and sulfate groups, suggesting it to be a sulfated galactan. Furthermore, porphyran treatment in the concentration range of 0–200 μg/mL had no significant toxicity no HUVECs, but instead promote cell proliferation, adhesion, migration, and vascular network formation. Further studies demonstrated that porphyran exerted its pro-angiogenic effect primarily by mediating the down-regulation of E-cadherin expression and the up-regulation of N-cadherin expression through the c-Jun N-terminal kinase (JNK) MAPK and VEGF receptor signaling pathways. In conclusion, porphyran has pro-angiogenic potential, which will provide a scientific basis for the development of porphyran as a novel pro-angiogenic factor and the precision nutrition-guided deep processing and high-value utilization of the red seaweed P. yezoensis.

ObjectiveTo investigate the dynamic changes of autophagy in infarcted cortex at different stages after ischemic stroke, and the relationship between phospholipase D1 (PLD1) activity, autophagy, and the neurological function in mice.MethodsFirstly, twenty-one male C57BL/6 mice at age of 8 weeks were used to establish ischemic stroke models, and they were randomly divided into sham surgery and ischemic stroke groups. The groups were furtherly divided into 4-, 6-, 8-, 12-, 24-, and 72-hour groups according to the onset of ischemic strok with three mice in each group. Dynamic expression and change of autophagy-related protein LC3 in the infarcted cortex were observed using Western blotting method and immunofluorescence staining. Secondly, thirty-six male C57BL/6 mice at age of 8 weeks were randomly divided into the sham surgery group, the PBS treatment group, and different concentrations of phospholipase D activity inhibitor 5-fluoro-2-indolyl des-chlorohalopemide (FIPI) treatment groups containing 0.3, 0.9, 1.8, and 3.6 mg/kg, respectively. Each group comprised six mice. The optimal FIPI concentration and its effects on neurological function and infarcted volume were assessed by adhesive removal and whisker tests and TTC staining. Furthermore, nine male C57BL/6 mice at age of 8 weeks were divided into sham surgery group, intraperitoneal administration of PBS group, and 0.9 mg/kg FIPI group. Each group comprised three mice. The effects of FIPI on changes in autophagy-related protein LC3 were examined by Western blotting. Finally, thirty-six adult male C57BL/6 mice at age of 8 weeks were divided into sham surgery group, intraperitoneal administration of PBS group, and 0.9 mg/kg FIPI treatment groups at four time points (0, 4, 8, and 12 hours) after ischemic stroke. Furthermore, the neurological functions and infarcted volume were assessed by the adhesive removal and whisker tests as well as TTC staining with six mice in each group.ResultsThe ratio of LC3-Ⅱ/β-actin in the infarcted cortex increased, peaked at 24 hours (P＜0.05), and then gradually declined after ischemic stroke. Compared with the PBS group, the administration of 0.9 mg/kg FIPI significantly decreased the ratio of LC3-Ⅱ/β-actin (P＜0.05), reduced the infarcted area (P＜0.05), and ameliorated neurological functions (P＜0.05) more than those observed in the other concentration groups. Compared with the PBS group, in addition to 0.9 mg/kg FIPI without delay, the administration of 0.9 mg/kg FIPI at 4-, 8-, and 12-hour after ischemic stroke could also decrease the infracted volume (P＜0.05) and improve the neurological function (P＜0.05).ConclusionThe change of autophagy was the most obvious at 24-hour after ischemic stroke and inhibition of PLD1 could improve the recovery of neurological function after ischemic stroke. Meanwhile, in addition to administration of 0.9 mg/kg FIPI without delay, 4-, 8-, and 12-hour after ischemic stroke could also shrink the infracted volume and improve the neurological function. The inhibition of the PLD1 could extend the therapeutic window and provide a novel therapeutic strategy for the clinical treatment of cerebral stroke.

The industrial applications of the κ-carrageenases have been restricted by their poor thermostability. In this study, based on the folding free energy change (ΔΔG) and the flexibility analysis using molecular dynamics (MD) simulation for the alkaline κ-carrageenase KCgCD from Pseudoalteromonas porphyrae (WT), the mutant S190R was identified with improved thermostability. After incubation at 50 °C for 30 min, the residual activity of S190R was 63.7%, 25.7% higher than that of WT. The Tm values determined by differential scanning calorimetry were 66.2 °C and 64.4 °C for S190R and WT, respectively. The optimal temperature of S190R was 10 °C higher than that of WT. The κ-carrageenan hydrolysates produced by S190R showed higher xanthine oxidase inhibitory activity compared with the untreated κ-carrageenan. MD simulation analysis of S190R showed that the residues (V186–M194 and P196–G197) in F5 and the key residue R150 in F3 displayed the decreased flexibility, and residues of T169–N173 near the catalytic center displayed the increased flexibility. These changed flexibilities might be the reasons for the improved thermostability of mutant S190R. This study provides a useful rational design strategy of combination of ΔΔG calculation and MD simulation to improve the κ-carrageenase's thermostability for its better industrial applications. Key points: Mutant κ-carrageenase S190R is identified by rational design based on ΔΔG and MD simulation. Mutant κ-carrageenase S190R increases the thermostability. Mutant enzyme-treated κ-carrageenan exhibits high xanthine oxidase inhibitory activity. [ABSTRACT FROM AUTHOR]

The layer stacking order in 2D materials strongly affects functional properties and holds promise for next-generation electronic devices. In bulk, octahedral MoTe2 possesses two stacking arrangements, the ferroelectric Weyl semimetal Td phase and the higher-order topological insulator 1T′ phase. However, in thin flakes of MoTe2, it is unclear if the layer stacking follows the Td, 1T′, or an alternative stacking sequence. Here, we use atomic-resolution scanning transmission electron microscopy to directly visualize the MoTe2 layer stacking. In thin flakes, we observe highly disordered stacking, with nanoscale 1T′ and Td domains, as well as alternative stacking arrangements not found in the bulk. We attribute these findings to intrinsic confinement effects on the MoTe2 stacking-dependent free energy. Our results are important for the understanding of exotic physics displayed in MoTe2 flakes. More broadly, this work suggests c-axis confinement as a method to influence layer stacking in other 2D materials. The layer stacking order in 2D materials can be used to control functional properties. Here, the authors find a thickness effect, where thin flakes of MoTe2 display stacking arrangements different from bulk crystals. [ABSTRACT FROM AUTHOR]

Overactive microglia and severe neuroinflammation play crucial roles in the development of major depressive disorder. Preconditioning with lipopolysaccharide (LPS) provides protection against severe neuroinflammation. However, administering high doses of LPS to mice triggers depressive symptoms. Therefore, the optimal dose of LPS preconditioning needs to be determined by further experiments. LPS preconditioning is an effective agent in anti-inflammation and neuroprotection, but the mechanism by which LPS preconditioning acts in depression remain unclear. This study finds that the anti-inflammation mechanism of low-dose LPS preconditioning is mainly dependent on G-protein-coupled receptor 84 (GPR84). We use low-dose LPS for preconditioning and re-challenged mice or BV2 microglia with high-dose LPS. In addition, RNA-seq is used to explore underlying changes with LPS preconditioning. Low-dose LPS preconditioning reduces the expression of pro-inflammatory mediators and inhibits microglial activation, as well as suppresses the depressive-like behavior when the mice are re-challenged with high-dose LPS. Further investigation reveals that the tolerance-like response in microglia is dependent on the GPR84. Here, we show that low-dose LPS preconditioning can exert anti-inflammation effects and alleviates inflammation-induced depressive-like behavior in mice. As a potential therapeutic target for depression, LPS preconditioning needs to be given further attention regarding its effectiveness and safety. [ABSTRACT FROM AUTHOR]

The effect of black tea powder on the antioxidant activity and gel characteristics of fish balls from silver carp were investigated after freezing storage for 7 days. The results show that black tea powder with different concentrations of 0.1%, 0.2% and 0.3% (w/w) could significantly increase the antioxidant activity of fish balls (p < 0.05). In particular, at the concentration of 0.3%, the antioxidant activity was the strongest among these samples, where the reducing power, DPPH, ABTS and OH free radical scavenging rate were up to 0.33, 57.93%, 89.24% and 50.64%, respectively. In addition, black tea powder at the level of 0.3% significantly increased the gel strength, hardness and chewiness while greatly reducing the whiteness of the fish balls (p < 0.05). ESEM observation found that the addition of black tea powder could promote the crosslinking of proteins and reduced the pore size of the gel network structure of the fish balls. The results suggest that black tea powder could be used as a natural antioxidant and gel texture enhancer in fish balls, which we found to be much related to the phenolic compounds of black tea powder. [ABSTRACT FROM AUTHOR]

Aiming at the low force density and the lack for lack of self-holding ability at the end of conventional moving-coil electromagnetic linear actuators, a novel compound electromagnetic linear actuator was proposed. According to the structural characteristics, the mathematical model was established; also the cooperative drive mode with high driving capability and the single drive mode with low energy consumption were analyzed. Combining the inverse system and the feed-forward + PI feedback algorithm, the multi-mode coordinated controller of the compound electromagnetic linear actuator was designed. A simulation model was established by MATLAB/Simulink, and a prototype test platform was built. The effectiveness of the coordinated control method was verified through simulation and experiments. The results show that the actuator has good dynamic characteristics under different driving modes, and the displacement control errors are less than ± 0.02 mm. The self-holding force of actuator is as 229.3 N. In the cooperative driving mode, the driving force may reach 574.9 N, and the turn-on transition time is as 4.8 ms; the turn-on transition time under the single drive is as 6.9 ms. [ABSTRACT FROM AUTHOR]

Simple Summary: The yak (Bos grunniens) is endemic to the Qinghai-Tibetan Plateau, and data on their nutritional requirements are lacking. Previous reports have shown that yaks have a higher nitrogen utilization efficiency than Bos taurus, so we hypothesize that yak diets should have a lower level of dietary crude protein than beef cattle. Two diets with different dietary protein content were designed to investigate the effect of dietary protein levels on yaks in the cold season. The results showed that during the cold season, high protein level could promote rumen microbial protein synthesis, elevate arginine and proline metabolism, purine and pyrimidine metabolism, taste transduction and glutathione metabolism pathways, enhance antioxidant and immune function, and promote growth performance of yak. However, a high-protein diet enhanced the renin secretion pathway, which might increase a yak's water intake. This experiment was aimed to compare the effects of two diets with different protein content on the growth performance, immune indexes, rumen fermentation characteristics and plasma metabolomics of growing yak in the cold season. A total of 24, 2-year-old healthy yaks with similar body weight (142.9 ± 3.56 kg) were randomly allocated to two isoenergetic diets with different protein content (10 vs 14%) according to a non-paired experimental design, and the protein of the diets was increased by increasing soybean meal, rapeseed meal and cottonseed meal. The growth performance experiment lasted 56 days. Four days before the end of the growth experiment, the digestion trial was conducted, and the rumen fluid and plasma was collected for measurement. The results showed that the average daily feed intake (p < 0.001) and average daily gain (p = 0.006) of yak fed a high-protein diet was significantly greater, while the feed conversion ratio was lower (p = 0.021) than that of yaks fed a low-protein diet. Plasma aspartate aminotransferase (p = 0.002), alanine aminotransferase (p < 0.001), malondialdehyde (p = 0.001), tumor necrosis factor-α (p = 0.032) and interferon-γ (p = 0.017) of the high-protein group were significantly lesser, whereas superoxide dismutase (p = 0.004) and interleukin-2 (p = 0.007) was significantly greater than that of the low-protein group. The rumen microbial crude protein (p < 0.047) and crude protein digestibility (p = 0.015) of yak fed a high-protein diet was significantly greater than that of the low-protein group. The metabolomics results showed that yaks fed a high-protein diet were elevated in protein digestion and absorption, arginine and proline metabolism, tryptophan metabolism, purine metabolism, butanoate metabolism, taste transduction, pyrimidine metabolism, pantothenate and CoA biosynthesis, glutathione metabolism and renin secretion pathways. It is concluded that a high-protein diet in the cold season can promote rumen microbial crude protein synthesis, enhance antioxidant and immune function and promote growth performance of yaks. [ABSTRACT FROM AUTHOR]

Drought-induced risk has attracted the attention of many scholars, but the risk of combined events caused by drought and high-temperature heat waves still needs further study. Based on MODIS products and meteorological data, the spatiotemporal variation characteristics of summer drought and high-temperature heat waves in the North China Plain from 2000 to 2018 were analyzed by the standardized precipitation evapotranspiration index (SPEI), crop water stress index (CWSI) and high-temperature threshold, and their combined-events risk was evaluated. The results showed that (1) from 2000 to 2018, summer drought in the North China Plain became more severe. Especially in Henan, Anhui and Jiangsu Provinces, drought increased significantly. (2) From 2000 to 2018, the frequency and intensity of high-temperature heat wave events in the North China Plain gradually increased at rates of 0.28 times/10 year and 1.6 °C/10 year, respectively. (3) The slightly high risk and high risk caused by summer drought were mainly distributed in Hebei Province and Tianjin Municipality in the north, and the risk change was characterized by a decrease in the north and an increase in the south. (4) The combined-events risk of summer drought and high-temperature heat waves did not increase significantly, with an increase rate of approximately 0.01/10 year. Among them, the increase rate of combined-events risk in Henan Province was the largest (0.14/10 year), followed by the obvious increase in northern Anhui, Jiangsu and southern Shandong, while the risk in Beijing showed a decreasing trend. The research results have scientific guiding significance for formulating disaster prevention and reduction strategies. [ABSTRACT FROM AUTHOR]

Much attention has recently been devoted to the qualitative relationship between climate factors and drought; however, the influences of climate variability, land-use/cover changes (LUCC), and other human activities on drought have rarely been quantitatively assessed. Based on the Soil and Water Assessment Tool (SWAT) model and the Palmer drought severity index (PDSI), this study presents a framework to quantify drought changes in an attribution study, and quantifies the effects of climate factors, LUCC, and other human activities on drought in a typical basin (Yihe River) in eastern China from 1980 to 2019. (1) The SWAT–PDSI results revealed a slight decreasing trend from 1980 to 2019, indicating that the degree of drought increased—especially in the middle of the basin. (2) The precipitation in the basin exhibited a downward trend (−2.7 mm/10 a), while the temperature exhibited a significant increasing trend (0.13 °C/10 a, p < 0.05). Over the past 40 years, LUCC in the Yihe River Basin was mainly characterized by a reduction in the dryland area (149 km2) and an increase in the built-up area (135 km2), which changed by −1.77% and 18.96%, respectively. (3) Climate fluctuation was the main driving factor of drought change, with a contribution rate ranging from 68 to 84%, and the contribution to drought gradually increased. Among the various factors, the contribution of temperature exceeded that of precipitation from 2010 to 2019, suggesting that temperature has become the most important climate factor affecting drought. The contribution rates of LUCC to drought changes over the periods 1990–1999, 2000–2009, and 2010–2019 were 7.8%, 18%, and 12.6%, respectively. This indicates that the relative contributions of other human activities to drought changes gradually decreased. This study refines the drought attribution framework, which could provide scientific support for the quantitative attribution of drought and the formulation of disaster prevention and reduction strategies. [ABSTRACT FROM AUTHOR]

Astrocyte scar formation after spinal cord injury (SCI) efficiently limits the accurate damage but physically restricts the following axon regeneration. Lately, fine tuning scar formation is becoming a novel strategy to develop SCI treatment, yet how to leverage these opposite effects remains challenging. Here, utilizing an improved drug administration approach, we show that in a mouse model of spinal cord injury, continual deletion of microglia, especially upon scar formation, by pexidartinib decreases the amount of microglia-derived collagen I and reforms the astrocyte scar. The astrocytes become less compacted in the scar, which permits axon regeneration and extension. Although continual microglia deletion did not significantly improve the locomotive performance of the SCI mice, it did ameliorate their weight loss, possibly by improving their relevant health conditions. We thus identified a novel approach to regulate astrocyte scars for improved axon regeneration, which is indicative of the clinical treatment of SCI patients. [ABSTRACT FROM AUTHOR]

Chondroitinase plays an important role in structural and functional studies of chondroitin sulfate (CS). In this study, a new member of chondroitinase B of PL6 family, namely ChSase B6, was cloned from marine bacterium Microbulbifer sp. ALW1 and subjected to enzymatic and structural characterization. The recombinant ChSase B6 showed optimum activity at 40 °C and pH 8.0, with enzyme kinetic parameters of Km and Vmax against chondroitin sulfate B (CSB) to be 7.85 µg/mL and 1.21 U/mg, respectively. ChSase B6 demonstrated thermostability under 60 °C for 2 h with about 50% residual activity and good pH stability under 4.0–10.0 for 1 h with above 60% residual activity. In addition, ChSase B6 displayed excellent stability against the surfactants including Tween-20, Tween-80, Trion X-100, and CTAB. The degradation products of ChSase B6-treated CSB exhibited improved antioxidant ability as a hydroxyl radical scavenger. Structural analysis and site-directed mutagenesis suggested that the conserved residues Lys248 and Arg269 were important for the activity of ChSase B6. Characterization, structure, and molecular dynamics simulation of ChSase B6 provided a guide for further tailoring for its industrial application for chondroitin sulfate bioresource development. [ABSTRACT FROM AUTHOR]

A core transcriptional regulatory circuit (CRC) is a group of interconnected auto-regulating transcription factors (TFs) that form loops and can be identified by super-enhancers (SEs). Studies have indicated that CRCs play an important role in defining cellular identity and determining cellular fate. Additionally, core TFs in CRCs are regulators of cell-type-specific transcriptional regulation. However, a global view of CRC properties across various cancer types has not been generated. Thus, we integrated paired cancer ATAC-seq and H3K27ac ChIP-seq data for specific cell lines to develop the Cancer CRC (http://bio.liclab.net/Cancer%5fcrc/index.html). This platform documented 94,108 cancer CRCs, including 325 core TFs. The cancer CRC also provided the "SE active core TFs analysis" and "TF enrichment analysis" tools to identify potentially key TFs in cancer. In addition, we performed a comprehensive analysis of core TFs in various cancer types to reveal conserved and cancer-specific TFs. [ABSTRACT FROM AUTHOR]

Red seaweed contains abundant bioactive ingredients with health benefits. Fermentation is widely used in improving the bioactive ingredients of seaweed materials. However, the types of the active metabolite and changes in biological activity components by the fermentation process remain unknown. In this study, red seaweed Bangia fusco-purpurea was inoculated with Lactobacillus delbrueckii and Lactobacillus plantarum to study bioactive components in supernatants. Results showed that Lactobacillus -fermentation dramatically increased free essential amino acid, trace mineral elements, flavonoids, and polyphenols contents, while decreasing protein and sugar in supernatants. Meanwhile, inhibitions of pancreatic lipase enzyme activities and antibacterial activities against oral pathogenic bacteria were significantly increased by Lactobacillus -fermentation, up to 93.48% and 98.2%, respectively. It might be caused by the increase of polyphenols and flavonoids contents in fermentation supernatants. Also, the biological functions of L. delbrueckii -fermentation were better than that of L. plantarum. Overall, B. fusco-purpurea with Lactobacillus -fermentation has the potential to be special dietary food for improving hyperlipidemia and obesity. [Display omitted] • B. fusco-purpurea was inoculated with Lactobacillus to study bioactive components. • Lactobacillus -fermentation increased polyphenols, essential amino acid and minerals. • Inhibition of pancreatic lipase activity and antibacterial activity were increased. • Fermentation of B. fusco-purpurea is special dietary for hyperlipidaemia and obesity. [ABSTRACT FROM AUTHOR]

• A new β-glucosidase gene was isolate from a marine bacterial strain. • The β-glucosidase exhibited glucose stimulation. • An asparagine residue conferred glucose stimulation property of the β-glucosidase. Glucose-tolerant and/or glucose-stimulated β-glucosidase is of great interest for its industrial utilization in enzymatic digestion of lignocellulosic biomass for biofuel production. In this study, a new gene of β-glucosidase MaGlu1A was cloned from an alginate-degrading marine bacterium Microbulbifer sp. ALW1. The gene of MaGlu1A encoded a 472-amino acid protein classified into the glycosyl hydrolase family 1 (GH1). The recombinant β-glucosidase was overexpressed and purified from Escherichia coli with a molecular mass of 65.0 kDa. Structure analysis illustrated the catalytic acid/base residue Glu186 and nucleophilic residue Glu370 in the enzyme. MaGlu1A displayed optimal activity at 40 °C and pH 4.5, respectively. It had substrate preference to the aryl-β-glycosidic bonds with glucose, fucose, and galactose moieties, in addition to cellobiose. MaGlu1A demonstrated strong stimulation to the supplemental glucose. Site-directed mutagenesis suggested an essential role of Asn242 in glucose stimulation. The enzymatic characterization of MaGlu1A provides general information about its catalytic properties facilitating its practical applications. [ABSTRACT FROM AUTHOR]