A family 5 β-mannanase from the thermophilic fungus Thielavia arenaria XZ7 with typical thermophilic enzyme features

A novel β-mannanase gene, man5XZ7, was cloned from thermophilic fungus Thielavia arenaria XZ7, and successfully expressed in Pichia pastoris. The gene (1,110 bp) encodes a 369-amino acid polypeptide with a molecular mass of approximately 40.8 kDa. The deduced sequence of Man5XZ7 consists of a putative 17-residue signal peptide and a catalytic module belonging to glycoside hydrolase (GH) family 5, and displays 76 % identity with the experimentally verified GH 5 endo-β-1,4-mannanase from Podospora anserina. Recombinant Man5XZ7 was optimally active at 75 °C and pH?5.0 and exhibited high activity at a wide temperature range (>50.0 % activity at 50–85 °C). Moreover, it had good adaptability to acidic to basic pH (>74.1 % activity at pH?4.0–7.0 and 25.6 % even at pH?9.0) and good stability from pH?3.0 to 10.0. These enzymatic properties showed that Man5XZ7 was a new thermophilic and alkali-tolerant β-mannanase. Further amino acid composition analysis indicated that Man5XZ7 has several characteristic features of thermophilic enzymes.     

Comparison of Risk Factor between Lacunar Stroke and Large Artery Atherosclerosis Stroke: A Cross-Sectional Study in China

Background

Stroke is the second most common cause of mortality in China. Although most subtypes of ischemic stroke share similar risk factors, they have different etiologies. Our study aimed to evaluate the different risk factor profiles between the stroke subtypes, lacunar infarcts (LI) and large-artery atherosclerosis (LAA), and clarify the characteristics of current acute ischemic stroke in China.

Methods

In this cross-sectional study, we analyzed the clinical characteristics of 1982 patients with acute ischemic stroke who were admitted to the neurology department at the Peking University First Hospital between 2007 and 2014. Ischemic stroke was further classified into LAA, LI, cardioembolism (CE) and undetermined causes of infarction (UDI) according to TOAST classification. Demographic characteristics, risk factors, as well as the findings of laboratory and imaging tests of 1773 patients with LAA and LI, were analyzed by univariate and multivariate logistic analysis.

Results

Of the 1982 ischemic stroke patients included in this study, 1207 were diagnosed with LAA, 566 with LI, 173 with cardioembolism (CE) and 36 with undetermined causes of infarction (UDI). By comparing the risk factors in multivariate logistic regression analysis, hypertension [odds ratio (OR) = 1.832] and white matter leukoaraiosis (WML) (OR = 1.865) were found to be more strongly correlated with LI than LAA. Low density lipoprotein- cholesterol (LDL-c) (OR = 0.774) were more strongly related to LAA than LI.

Conclusions

This study found that hypertension and WML were more strongly correlated with LI than LAA. LDL-c was more strongly related to LAA than LI.     

Vildagliptin improves high glucose‐induced endothelial mitochondrial dysfunction via inhibiting mitochondrial fission

The dipeptidyl peptidase 4 inhibitor vildagliptin (VLD), a widely used anti‐diabetic drug, exerts favourable effects on vascular endothelium in diabetes. We determined for the first time the improving effects of VLD on mitochondrial dysfunction in diabetic mice and human umbilical vein endothelial cells (HUVECs) cultured under hyperglycaemic conditions, and further explored the mechanism behind the anti‐diabetic activity. Mitochondrial ROS (mtROS) production was detected by fluorescent microscope and flow cytometry. Mitochondrial DNA damage and ATP synthesis were analysed by real time PCR and ATPlite assay, respectively. Mitochondrial network stained with MitoTracker Red to identify mitochondrial fragmentation was visualized under confocal microscopy. The expression levels of dynamin‐related proteins (Drp1 and Fis1) were determined by immunoblotting. We found that VLD significantly reduced mtROS production and mitochondrial DNA damage, but enhanced ATP synthesis in endothelium under diabetic conditions. Moreover, VLD reduced the expression of Drp1 and Fis1, blocked Drp1 translocation into mitochondria, and blunted mitochondrial fragmentation induced by hyperglycaemia. As a result, mitochondrial dysfunction was alleviated and mitochondrial morphology was restored by VLD. Additionally, VLD promoted the phosphorylation of AMPK and its target acetyl‐CoA carboxylase in the setting of high glucose, and AMPK activation led to a decreased expression and activation of Drp1. In conclusion, VLD improves endothelial mitochondrial dysfunction in diabetes, possibly through inhibiting Drp1‐mediated mitochondrial fission in an AMPK‐dependent manner.     

Monitoring rapid vegetation succession in estuarine wetland using time series MODIS-based indicators: An application in the Yangtze River Delta area

Frequent and continuous time series is required for the detection of plant phenology and vegetation succession. The launch of novel remote sensor MODIS (moderate resolution imaging spectroradiometer) provided us with an opportunity to make a new trial of studying the rapid vegetation succession in estuarine wetlands. In this study, the spatiotemporal variations of vegetation cover and tidal flat elevation along a transect (covering 6 pixels of MODIS) of an estuarine wetland at Dongtan, Chongming Island, in Yangtze River estuary, China were investigated to assess its rapid vegetation succession and physical conditions. By combining the field data collected, the time series of MODIS-based VIs (vegetation indices), including NDVI (normalized difference vegetation index), EVI (enhanced vegetation index) and MSAVI (modified soil adjusted vegetation index), and a water index, LSWI (land surface water index) were utilized to characterize the rapid vegetation succession between 2001 and 2006. We found that NDVI, EVI and MSAVI exhibited significant spatial and temporal correlations with vegetation succession, while LSWI behaved in a positive manner with surface water and soil moisture along with the successional stages. In order to take the advantages of both VIs and water index, a composite index of VWR (vegetation water ratio) combining LSWI and EVI or MSAVI was proposed in this paper. This index facilitates the identification of vegetation succession by simply comparing the values of VWR at different stages, and therefore it could track vegetation succession and estimate community spread rate. Additionally, this study presented an attempt of using MODIS datasets to monitor the change of tidal flat elevation, which demonstrated a potential remote sensing application in geodesy of coastal and estuarine areas.     

江口萝卜猪FABPs主要家族基因SNPs筛选及生物信息学分析

以江口萝卜猪为试验材料构建DNA池,采用直接测序技术对猪L-FABP、I-FABP、H-FABP、A-FABP基因进行SNPs快速筛查,共检测出7个SNPs,分别为intron1-T1745C、exon2-T125C、exon2-A131C、exon2-C153A、exon2-A65T、exon2-G40A、intron3-C65T。其中intron1-T1745C、intron3-C65T位于内含子上;exon2-T125C、exon2-C153A为同义突变;exon2-A131C、exon2-A65T、exon2-G40A为错义突变,分别使编码氨基酸发生Glu→Ala、Lys→Met、Glu→Lys的改变,对其进行生物信息学分析表明,突变前后的等位基因频率估算,mR NA二级结构预测,蛋白质二级、三级结构预测分析均有差异。     

High-Pressure Inactivation of Rotaviruses: Role of Treatment Temperature and Strain Diversity in Virus Inactivation

Rotavirus (RV) is the major etiological agent of acute gastroenteritis in infants worldwide. Although high-pressure processing (HPP) is a popular method to inactivate enteric pathogens in food, the sensitivity of different virus strains within same species and serotype to HPP is variable. This study aimed to compare the barosensitivities of seven RV strains derived from four serotypes (serotype G1, strains Wa, Ku, and K8; serotype G2, strain S2; serotype G3, strains SA-11 and YO; and serotype G4, strain ST3) following high-pressure treatment. RV strains showed various responses to HPP based on the initial temperature and had different inactivation profiles. Ku, K8, S2, SA-11, YO, and ST3 showed enhanced inactivation at 4°C compared to 20°C. In contrast, strain Wa was not significantly impacted by the initial treatment temperature. Within serotype G1, strain Wa was significantly (P < 0.05) more resistant to HPP than strains Ku and K8. Overall, the resistance of the human RV strains to HPP at 4°C can be ranked as Wa > Ku = K8 > S2 > YO > ST3, and in terms of serotype the ranking is G1 > G2 > G3 > G4. In addition, pressure treatment of 400 MPa for 2 min was sufficient to eliminate the Wa strain, the most pressure-resistant RV, from oyster tissues. HPP disrupted virion structure but did not degrade viral protein or RNA, providing insight into the mechanism of viral inactivation by HPP. In conclusion, HPP is capable of inactivating RV at commercially acceptable pressures, and the efficacy of inactivation is strain dependent.     

Quantitative analysis of free fatty acids in rat plasma using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with meso-tetrakis porphyrin as matrix

Quantitative analysis of free fatty acids was achieved using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with a meso-tetrakis porphyrin matrix. Cesium acetate was employed as a cationizing agent. The MALDI signal was reproducible and dominated by cesiated cesium carboxylates [RCOOCs + Cs]+. The addition of two Cs ions resulted in a mass shift of 264.8 Da for each fatty acid and greatly reduced background peaks. A linear relationship between fatty acid concentration and corresponding fatty acid to internal standard peak intensity ratio was observed for three representative fatty acids analyzed across a concentration range from 4.40 to 150 microM, with correlation coefficients between 0.986 and 0.987. The application of this method was demonstrated with the analysis of free fatty acids in nonfasted and fasted rat plasmas. A total of eight free fatty acids (14:0, 16:0, 16:1, 17:0, 18:0, 18:1, 18:2, and 20:4) were detected. The relative peak height ratios of the fatty acids to the internal standard allow quantitative measurements of the free fatty acids. It was shown that the levels of free fatty acids were higher in fasted rats than in rats in a nonfasted state. This method is simple, sensitive, and fast. Thus, it provides an appealing tool for the analysis of free fatty acids or other low-molecular weight compounds during drug discovery and/or development.     

Noninvasive determination of spatial distribution and temporal gradient of wall shear stress at common carotid artery

Wall shear stress (WSS) has been proved to play a critical role in formation and development of atherosclerotic plaques. Our objective was to quantify local WSS in vivo in normal subjects, and to analyze spatial distribution patterns and determine the temporal gradient of WSS. Seventy-eight CCAs of 42 healthy volunteers at common carotid arteries (CCAs) were studied. Cine phase-contrast MR sequence was used to acquire the flow velocity information. Three-dimensional paraboloid modeling was applied to fit the velocity profiles and WSS values were calculated. Mean WSS value for CCAs was 0.783+/-0.209, with the range of WSS value from -0.541 to 3.464 N/m(2). The 95% confidence interval for mean WSS value in CCA was (0.736-0.830) N/m(2). Different WSS spatial distribution patterns were classified into three types according to the location of low WSS values during a cardiac cycle. Mean value of maximum temporal gradient of WSS was 14.12+/-5.46, with the range from 5.87 to 33.23 N/m(2)s(-1). Skewed velocity profiles were displayed in most CCAs, indicating the flow patterns in CCA were more complicated than commonly assumed. Obvious inter-subject variation were found in magnitude, spatial distribution and the temporal gradient of WSS in CCAs, and the blood flow patterns as well.     

Erosion reduces soil microbial diversity,network complexity and multifunctionality

While soil erosion drives land degradation, the impact of erosion on soil microbial communities and multiple soil functions remains unclear. This hinders our ability to assess the true impact of erosion on soil ecosystem services and our ability to restore eroded environments. Here we examined the effect of erosion on microbial communities at two sites with contrasting soil texture and climates. Eroded plots had lower microbial network complexity, fewer microbial taxa, and fewer associations among microbial taxa, relative to non-eroded plots. Soil erosion also shifted microbial community composition, with decreased relative abundances of dominant phyla such as Proteobacteria, Bacteroidetes, and Gemmatimonadetes. In contrast, erosion led to an increase in the relative abundances of some bacterial families involved in N cycling, such as Acetobacteraceae and Beijerinckiaceae. Changes in microbiota characteristics were strongly related with erosion-induced changes in soil multifunctionality. Together, these results demonstrate that soil erosion has a significant negative impact on soil microbial diversity and functionality.Subject terms: Soil microbiology, Microbial ecology