Structure Characterization and Anti-exercise Fatigue Effect of Selenium Polysaccharide from Morchella esculenta

Objective: To clarify the structural characteristics of selenium polysaccharides from Morchella esculenta, and their ameliorative effects on exercise-fatigued rats. Methods: Polysaccharides from Morchella esculenta were extracted using ultrasound-assisted hot water extraction. Purified polysaccharides (Msp-1) were obtained through DEAE cellulose column chromatography and Sephadex G-100 column chromatography. Nitric acid-sodium selenite method was used to prepare selenized polysaccharide (Se-Msp1) from purified polysaccharides. The structures of Msp-1 and Se-Msp1 were characterized. The swimming time of rats was measured by exhaustive swimming test, and the weighted swimming model was established at the same time. The rats were randomly divided into quiet control group, exercise fatigue control group, positive control group (salidroside, 100 mg/kg), normal polysaccharide group (Msp-1, 100 mg/kg), and selenized polysaccharide low, medium, and high dose groups (Se-Msp1, 50, 100, and 200 mg/kg, respectively). The rats were orally administered with 0.1 mL/(10 g·bw) for 5 weeks. The content of blood lactic acid (BLA), blood urea nitrogen (BUN), hepatic glycogen (HG), and muscular glycogen (MG), as well as malondialdehyde (MDA) content, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities in skeletal muscle mitochondria, were measured to evaluate the anti-exercise fatigue effect of Se-Msp1. Results: The major component of the purified polysaccharides from Morchella esculenta was Msp-1, which accounted for 85.25%. Infrared spectroscopy showed that the heteromeric carbon of Se-Msp1 was α configuration, and characteristic absorption peaks of selenium were observed, indicating that Se-Msp1 was successfully selenided. The Se content in Se-Msp1 was 9.56 mg/g, the polysaccharide content was 56.34%, with uronic acid content of 36.82%, and the weight average molecular weight was 3.482×105 Da, particle size of 384.71 nm, zeta potential was −45.78 mV, indicating that Se-Msp1 had a high selenium content and good stability. The monosaccharide composition of Se-Msp1 consisted of mannose, glucose, galactose, galacturonic acid, and rhamnose, with molar ratios of 1:0.42:3.57:3.34:1.86. The anti fatigue results of rats showed that compared with the control group (Con), both Msp-1 and Se-Msp1 significantly increased the exhausted swimming time (P<0.01), demonstrating good anti fatigue effects. The weighted swimming model results of rats showed that compared with the exercise fatigue control group, the content of hepatic glycogen and muscular glycogen in the low, middle and high dose groups of Se-Msp1 were significantly increased (P<0.01), while the blood lactic acid and blood urea nitrogen were significantly reduced (P<0.01). Se-Msp1 at low, medium, and high doses significantly increased the HG and MG content (P<0.01), and reduced the levels of BLA and BUN (P<0.01). In addition, The MDA content in skeletal muscle mitochondria were also significantly reduced (P<0.01), and the antioxidant enzyme activities (SOD, CAT, GSH Px) were significantly increased (P<0.01), and Se-Msp1 exhibited higher antioxidant activity than Msp-1. Conclusion: In summary, the prepared selenium rich polysaccharide from Morchella esculenta (Se-Msp1) had a stable structure and high anti-exercise fatigue activity, providing a theoretical basis for the development of selenium rich polysaccharide products from Morchella esculenta

Whole genome sequencing of foodborne pathogens and global data sharing development

With the rapid development of molecular typing techniques for monitoring foodborne pathogens and outbreak investigations, whole genome sequencing (WGS) is gradually revealing its importance. In the context of the globalization of food trade, it’s urgent to establish details of the links between foodborne pathogens and human exposure in order to accurately monitor and reduce their occurrence. The accuracy of WGS is significantly better than prior analysis tools in the aspect. In this paper, we take Listeria monocytogenes as example to expound the monitoring of foodborne pathogens and the investigation of infection outbreaks, emphasizing the value of WGS in trace-back of foodborne diseases. The technologies for data generation and analysis are summarized, the practical application progress of WGS in the worldwide foodborne pathogen typing is emphasized, and the challenges in the future are prospected

MicroRNA-141 Represses HBV Replication by Targeting PPARA

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression primarily at the post-transcriptional level and play critical roles in a variety of physiological and pathological processes. In this report, miR-141 was identified to repress HBV expression by screening a small miRNA expressing library and synthetic miR-141 mimics could also significantly suppress HBV expression and replication in HepG2 cells. Bioinformatic analysis and experiment assays indicate that peroxisome proliferator-activated receptor alpha (PPARA) was the target of hsa-miR-141 during this process. Furthermore, knockdown of PPARA by small interfering RNA (siRNA) inhibited HBV replication similar to levels observed for miR-141. Promoter functional analysis indicated that repression of HBV replication by miR-141 mimics or siRNA was mediated by interfering with the HBV promoter functions, consistent with previous studies demonstrating that PPARA regulated HBV gene expression through interactions with HBV promoter regulatory elements. Our results suggest that miR-141 suppressed HBV replication by reducing HBV promoter activities by down-regulating PPARA. This study provides new insights into the molecular mechanisms associated with HBV-host interactions. Furthermore, this information may facilitate the development of novel anti-HBV therapeutic strategies

Parameters Optimization for a Kind of Dynamic Vibration Absorber with Negative Stiffness

A new type of dynamic vibration absorber (DVA) with negative stiffness is studied in detail. At first, the analytical solution of the system is obtained based on the established differential motion equation. Three fixed points are found in the amplitude-frequency curves of the primary system. The design formulae for the optimum tuning ratio and optimum stiffness ratio of DVA are obtained by adjusting the three fixed points to the same height according to the fixed-point theory. Then, the optimum damping ratio is formulated by minimizing the maximum value of the amplitude-frequency curves according to H∞ optimization principle. According to the characteristics of negative stiffness element, the optimum negative stiffness ratio is also established and it could still keep the system stable. In the end, the comparison between the analytical and the numerical solutions verifies the correctness of the analytical solution. The comparisons with three other traditional DVAs under the harmonic and random excitations show that the presented DVA performs better in vibration absorption. This result could provide theoretical basis for optimum parameters design of similar DVAs