A novel lytic phage potentially effective for phage therapy against Burkholderia pseudomallei in the tropics.

BACKGROUND: Burkholderia pseudomallei is a tropical pathogen that causes melioidosis. Its intrinsic drug-resistance is a leading cause of treatment failure, and the few available antibiotics require prolonged use to be effective. This study aimed to assess the clinical potential of B. pseudomallei phages isolated from Hainan, China. METHODS: Burkholderia pseudomallei strain (HNBP001) was used as the isolation host, and phages were recovered from domestic environmental sources, which were submitted to the host range determination, lytic property assays, and stability tests. The best candidate was examined via the transmission electron microscope for classification. With its genome sequenced and analyzed, its protective efficacy against B. pseudomallei infection in A549 cells and Caenorhabditis elegans was evaluated, in which cell viability and survival rates were compared using the one-way ANOVA method and the log-rank test. RESULTS: A phage able to lyse 24/25 clinical isolates was recovered. It was classified in the Podoviridae family and was found to be amenable to propagation. Under the optimal multiplicity of infection (MOI) of 0.1, an eclipse period of around 20 min and a high titer (1012 PFU/ml) produced within 1 h were demonstrated. This phage was found stabile at a wide range of temperatures (24, 37, 40, 50, and 60 °C) and pH values (3-12). After being designated as vB_BpP_HN01, it was fully sequenced, and the 71,398 bp linear genome, containing 93 open reading frames and a tRNA-Asn, displayed a low sequence similarity with known viruses. Additionally, protective effects of applications of vB_BpP_HN01 (MOI = 0.1 and MOI = 1) alone or in combination with antibiotics were found to improve viability of infected cells (70.6 ± 6.8%, 85.8 ± 5.7%, 91.9 ± 1.8%, and 96.8 ± 1.8%, respectively). A significantly reduced mortality (10%) and a decreased pathogen load were demonstrated in infected C. elegans following the addition of this phage. CONCLUSIONS: As the first B. pseudomallei phage was isolated in Hainan, China, phage vB_BpP_HN01 was characterized by promising lytic property, stability, and efficiency of bacterial elimination during the in vitro/vivo experiments. Therefore, we can conclude that it is a potential alternative agent for combating melioidosis

Parameter Estimation for Robotic Manipulator Systems

In this paper, a novel methodology for estimating the parameters of robotic manipulator systems is proposed. It can be seen that, for the purpose of parameter estimation, the input torque to each joint motor is designed as a linear combination of sinusoids. After the transient responses of joint angles exponentially converge to zero, the steady states of joint angle outputs can be extracted. Since the steady states of joint angles are the equivalent finite Fourier series, the coefficients of the steady state components of joint angles can be further extracted in a fundamental period. With the amazing finding that the steady states contain all dynamic information of manipulator systems, all unknown parameters of the system model can be accurately estimated with the extracted coefficients in finite frequency bands. The simulation results for a two-link manipulator are carried out to illustrate the effectiveness and robustness against measurement noise of the proposed method

Root-Securing and Brain-Fortifying Liquid Upregulates Caveolin-1 in Cell Model with Alzheimer’s Disease through Inhibiting Tau Phosphorylation

In order to explore the effect of root-securing and brain-fortifying Liquid- (RSBFL-) mediated caveolin-1 (CAV-1) on phosphorylation of Tau protein and to uncover underlying mechanisms of RSBFL for the prevention and treatment of Alzheimer’s disease (AD), hippocampal neurons isolated from neonatal SD rats and cultured in DMEM-F12 medium were induced by exogenous Aβ1–42 to establish a cell model with AD. Meanwhile, pEGFP-C1-CAV1 and CAV1-shRNA plasmids were transfected into hippocampal neurons for CAV-1 overexpression and silence, respectively. The serum containing RSBFL was prepared for the intervention of AD model cells. The expression of CAV-1, GSK-3β, and p-Tau in normal hippocampal neurons and AD model cells in the presence of serum containing RSBFL was evaluated. The model hippocampal neurons with AD induced by Aβ1–42 revealed an obvious CAV-1 inhibition, enhanced GSK-3β activity, and abnormal Tau phosphorylation. In contrast, the treatment with serum containing RSBFL could upregulate CAV-1 in AD hippocampal neurons (P<0.05) with improved p-GSK-3βSer9 and reduced p-GSK-3βTyr216 (P<0.01), as well as suppressed abnormal phosphorylation of Tau protein. Therefore, RSBFL has an excellent protective effect on hippocampal neurons through increasing CAV-1 expression, inhibiting GSK-3β activity, and reducing excessive abnormal phosphorylation of Tau protein

Exogenous Melatonin Improves the Quality Performance of Rice under High Temperature during Grain Filling

With the increasing greenhouse effect, high temperature has become the most unfavorable environmental factor for the rice grain filling process, affecting rice yield and quality mainly through changing the composition and structure of starch in rice grains. Research has focused on the rational management of water and fertilizer, and spraying of exogenous chemicals, which have become important measures to alleviate high temperature stress of rice. As a multifunctional molecule, melatonin has the potential to improve plant stress resistance by enhancing the scavenging efficiency of reactive oxygen species (ROS), thus protecting plants from the adverse effects of abiotic stress. The present study used a typical japonica rice variety Nipponbare (NPB) as the experimental material, which was treated with high temperature and melatonin during grain-filling stages. The effects of exogenous melatonin on the rice growth and quality traits, as well as starch synthesis, in response to high temperature were analyzed systematically. Exogenous melatonin significantly increased the rice leaf photosynthetic and heat-resistance properties. Melatonin could alleviate the effects of high temperature on the key physicochemical properties related to rice quality. Furthermore, milled rice from NPB plants treated with melatonin had better endosperm appearance under high temperature. Further study found that exogenous melatonin could stabilize the chain length distribution of starch in NPB (especially amylopectin), which implied that melatonin could be used in rice cultivation to alleviate the effect of high temperature on quality, optimization of amylopectin synthesis can also improve rice quality. The results of the present study provide a new idea and research direction to alleviate high temperature stress of rice in the context of global warming

Exogenous Melatonin Improves the Quality Performance of Rice under High Temperature during Grain Filling

With the increasing greenhouse effect, high temperature has become the most unfavorable environmental factor for the rice grain filling process, affecting rice yield and quality mainly through changing the composition and structure of starch in rice grains. Research has focused on the rational management of water and fertilizer, and spraying of exogenous chemicals, which have become important measures to alleviate high temperature stress of rice. As a multifunctional molecule, melatonin has the potential to improve plant stress resistance by enhancing the scavenging efficiency of reactive oxygen species (ROS), thus protecting plants from the adverse effects of abiotic stress. The present study used a typical japonica rice variety Nipponbare (NPB) as the experimental material, which was treated with high temperature and melatonin during grain-filling stages. The effects of exogenous melatonin on the rice growth and quality traits, as well as starch synthesis, in response to high temperature were analyzed systematically. Exogenous melatonin significantly increased the rice leaf photosynthetic and heat-resistance properties. Melatonin could alleviate the effects of high temperature on the key physicochemical properties related to rice quality. Furthermore, milled rice from NPB plants treated with melatonin had better endosperm appearance under high temperature. Further study found that exogenous melatonin could stabilize the chain length distribution of starch in NPB (especially amylopectin), which implied that melatonin could be used in rice cultivation to alleviate the effect of high temperature on quality, optimization of amylopectin synthesis can also improve rice quality. The results of the present study provide a new idea and research direction to alleviate high temperature stress of rice in the context of global warming

Study on the Synthesis and Properties of Biodegradable Poly(butylene diglycolate) Polyester

With increasing environmental requirements, biodegradable polymers have received widespread attention. Herein, we synthesized a series of poly(butylene diglycolate)s (PBDs), which was a novel biodegradable homopolyester, with number-average molecular weight (Mn) values between 13 and 97 K g·mol–1. The effects of Mn on the thermal and tensile properties of PBDs were comprehensively investigated. The glass transition temperature (Tg), melting temperature (Tm), and temperature of 5% weight loss (Td,5%) of PBDs were found to be approximately −26.4, 64.0, and 336 °C, respectively. PBD with 31 K g·mol–1 exhibits a brittle fracture feature, while obvious yielding behavior occurs when the Mn of PBD is higher than 45 K g·mol–1. Besides, PBD achieves stable mechanical properties when Mn reaches 51 K g·mol–1, with the elastic modulus, tensile strength, and elongation at break of 285, 27.1 MPa, and 290%, respectively, superior to those of linear low-density polyethylene (LLDPE). Furthermore, the crystal structures of PBD were recorded by WAXD and POM. The spherulites were observed after isothermal crystallization of PBD in a wide temperature range, and the maximum nucleation density was obtained after annealing at 20 °C. Significant hydrolysis of PBD in both buffer solution and artificial seawater was confirmed by monitoring the changes in residual weight, intrinsic viscosity, surface morphology, crystallinity, and chemical composition. Finally, PBD exhibits considerable biodegradability under composting and freshwater environments, with the residual weight reducing to 49.2 and 94.7% after 35 days, respectively. Due to the balanced mechanical and barrier properties and biodegradability, PBD has potential application prospects in packaging materials

High-Precision Dispensing of Nanoliter Biofluids on Glass Pedestal Arrays for Ultrasensitive Biomolecule Detection

Precise dispensing of nanoliter droplets is necessary for the development of sensitive and accurate assays, especially when the availability of the source solution is limited. Conventional approaches are limited by imprecise positioning, large shear forces, surface tension effects, and high costs. To address the need for precise and economical dispensing of nanoliter volumes, we developed a new approach where the dispensed volume is dependent on the size and shape of defined surface features, thus freeing the dispensing process from pumps and fine-gauge needles requiring accurate positioning. The surface we fabricated, called a nanoliter droplet virtual well microplate (nVWP), achieves high-precision dispensing (better than ±0.5 nL or ±1.6% at 32 nL) of 20–40 nL droplets using a small source drop (3–10 μL) on isolated hydrophilic glass pedestals (500 μm on a side) bonded to arrays of polydimethylsiloxane conical posts. The sharp 90° edge of the glass pedestal pins the solid–liquid–vapor triple contact line (TCL), averting the wetting of the glass sidewalls while the fluid is prevented from receding from the edge. This edge creates a sufficiently large energy barrier such that microliter water droplets can be poised on the glass pedestals, exhibiting contact angles greater >150°. This approach relieves the stringent mechanical alignment tolerances required for conventional dispensing techniques, shifting the control of dispensed volume to the area circumscribed by the glass edge. The effects of glass surface chemistry and dispense velocity on droplet volume were studied using optical microscopy and high-speed video. Functionalization of the glass pedestal surface enabled the selective adsorption of specific peptides and proteins from synthetic and natural biomolecule mixtures, such as venom. We further demonstrate how the nVWP dispensing platform can be used for a variety of assays, including sensitive detection of proteins and peptides by fluorescence microscopy or MALDI-TOF

The interaction between amylose and amylopectin synthesis in rice endosperm grown at high temperature

Starch is the abundant component in rice endosperm, and its microstructure determines the quality and functional properties of rice grain. It is well known that the starch fine structure is markedly influenced by high temperature during grain filling. However, it is poorly understood on the competition among starch synthesis related enzymes as well as the interaction between amylose and amylopectin biosynthesis under increased growing temperature. In this study, the non-waxy and waxy rice were planted under normal and high temperatures. Parameterizing analysis of the starch microstructure using mathematical models proved that amylose synthesis competed with the elongation of long amylopectin chains (DP＞60); Short chains of amylopectin can be used as the substrate for elongation of longer amylopectin chains; High temperature eliminated the consistency and regularity of the synthesis of amylose and amylopectin. In addition, enzyme assay proved the validity of fitting results from mathematical modeling analysis of starch