Probing enzymatic structure-function in the di-hydroxylating sesquiterpene synthase ZmEDS

Terpene synthases(TPSs) play a vital role in forming the complex hydrocarbon backbones that underlie terpenoid diversity. Notably, some TPSs can add water prior to terminating the catalyzed reaction, leading to hydroxyl groups, which are critical for biological activity. A particularly intriguing example of this is the maize (Zea mays) sesquiterpene TPS whose major product is eudesmanediol, ZmEDS. This production of dual hydroxyl groups is presumably enabled by protonation of the singly-hydroxylated transient stable intermediate hedycaryol. To probe the enzymatic structure-function relationships underlying this unusual reaction, protein modeling and docking were used to direct mutagenesis of ZmEDS. Previously, a F303A mutant was shown to produce only hedycaryol, suggesting a role in protonation. Here this is shown to be dependent on steric bulk positioning of hedycaryol, including a supporting role played by the nearby F299, rather than π-cation interaction. Among the additional residues investigated here, G411 at the conserved kink in helix G is of particular interest, as substitution for this leads to predominant production of the distinct(-)-valerianol, while substitution for the aliphatic I279 and V306 can lead to significant production of the alternative eudesmane-type diols 2,3-epi- cryptomeridiol and 3-epi-cryptomeridol, respectively. Altogether, nine residues important for this unusual reaction were investigated here, with the results not only emphasizing the importance of reactant positioning suggested by the stereospecificity observed between the various product types, but also highlighting the potential role of the Mg2+-diphosphate complex as the general acid for the protonation- initiated (bi)cyclization of hedycaryol

Electrochemiluminescent Detection of Hydrogen Peroxide via Some Luminol Imide Derivatives with Different Substituent Groups

Some luminol imide derivatives with different substituent groups have been designed and synthesized. Their electrochemiluminescence properties have been measured with a view to developing new biosensors. The ECL response to hydrogen peroxide in the presence of these luminescent derivatives has been investigated taking into account crucial factors such as the applied potential value, injection volume of hydrogen peroxide, and the substituent groups in molecular structures. The experimental data demonstrated that the substituent groups in these imide derivatives can have a profound effect upon the ECL abilities of these studied compounds. The present research work affords new and useful exploration for the design and development of new soft matter for ECL biosensors with luminol functional groups

Involvement of NMDA-AKT-mTOR Signaling in Rapid Antidepressant-Like Activity of Chaihu-jia-Longgu-Muli-tang on Olfactory Bulbectomized Mice

Background: Fast-onset antidepressants are urgently needed. Chaihu-jia-Longgu-Muli-tang (CLM), a classic Chinese herbal medicine, has been used for antidepressant treatment with long history. Olfactory bulbectomization (OB) model is validated for identification of rapid antidepressant efficacy. Here we used OB model for investigating the rapid onset activity of CLM in mice, and also tested the involvement of prefrontal Akt-mTOR and associated AMPA/NMDA receptors as well as hippocampal BDNF in the rapid antidepressant-like effect of CLM.Methods: The OB model was first characterized with depression-like behaviors and the time course changes of the behaviors. The fast onset of antidepressant effect of CLM was evaluated using sucrose preference test, tail suspension test and forced swim test in OB mice after a single administration. The expression of synaptic proteins of AMPA and NMDA subunits as well as Akt/mTOR signaling in the prefrontal cortex, and hippocampal BDNF was evaluated with the immunoblotting method.Results: A single dose of CLM significantly improved the deficiency in the sucrose preference and decreased the immobility time in the tail suspension test in OB mice. In the prefrontal cortex (PFC) in OB mice, there was lower expression level of the AMPA receptor subunit GluR1, rescued by a single dose of CLM. Additionally, the expression of NMDA subunit NR1 was up-regulated in OB mice, whereas mTOR and its upstream Akt signalings were both down-regulated. These deficiencies were reversed by a single dose of CLM. The CLM treatment also attenuated the expressions of NMDA receptor subunits NR2A and NR2B, which did not change in OB mice. In the hippocampus, expressions of GluR1 and brain derived neurotrophic factor (BDNF) were both up-regulated in OB mice, although CLM increased GluR1, but not BDNF.Conclusion: CLM elicited rapid antidepressant-like effects in the OB model mice, and CLM reversal of the abnormality in PFC expression of AMPA and NMDA receptors and associated Akt-mTOR signaling may underlie the effects

Heart Sound Biometric System Based on Marginal Spectrum Analysis

sensor

The research and application of smart weighing apparatus based on Linux and Qt

Through the investigation on the current weighing products,with the demand on development of modern weighing industry as the basis,this paper proposed a novel design of smart weighing apparatus. It takes ARMllS3C6410 as the MCU and embedded Linux as control system,and uses Linux and Qt to complete the control procedures and man-machine interface.It aloe uses WIFI communication technology to complete the remote communication and data acquisition.We use the STM32 chip to design the USB keyboard and use thermal printer to print transaction records.The approach based on the traditional weighing apparatus,joined with the network and database technology,makes the weighing apparatus more intelligent.Test results show that the system is stable,reliable and easy to operate

Indole primes plant defense against necrotrophic fungal pathogen infection.

Indole is a volatile compound and emitted from plants challenged by insect infestation or mechanic wounding. It has been shown to prime defense against herbivory. Here we identified that indole induced defense either directly or as a priming agent against necrotrophic pathogens Fusarium graminearum and F. moniliforme in maize and Magnaporthe oryzae in rice. With indole pretreatment, smaller lesions were developed in infected leaves, as well as less fungal growth. Indole induced H2O2 burst in the priming stage like other priming substances did. Such priming relied on mitogen-activated protein kinase (MAPK) cascade, which potentially activated downstream defense signaling. In addition, indole priming resulted in earlier and stronger defensive gene expression upon pathogen infection, including genes of jasmonate and phytoalexin biosynthesis, pathogenesis-related proteins (PRs) and anti-oxidant enzymes, which enhanced plant resistance. Meanwhile, H2O2 was also identified as the priming agent to induce plant defense. Taken together, indole exhibited priming function not only against herbivory but also necrotrophic pathogens. The common emission of indole in plants suggests that it plays important roles as the universal and endogenous priming substance in plant defense

The automotive anti-collision system based on Ultrasonic

In the existing system of automobile anti-collision,the radar is mainly used for ranging.However,it can't be widely used because of its high cost.In this paper,based on the existing system of automobile anti-collision,the ultrasonic sensor is used to measure the distance and establish relevant anti-collision model.The experimental results show that the alarming information is accurate within a certain range

Enzyme-catalyzed biodegradation of penicillin fermentation residues by β-lactamase OtLac from Ochrobactrum tritici

Abstract Background Biodegradation of antibiotics is a promising method for the large-scale removal of antibiotic residues in the environment. However, the enzyme that is involved in the biodegradation process is the key information to be revealed. Results In this study, the beta-lactamase from Ochrobactrum tritici that mediates the biodegradation of penicillin V was identified and characterized. When searching the proteins of Ochrobactrum tritici, the β-lactamase (OtLac) was identified. OtLac consists of 347 amino acids, and predicted isoelectric point is 7.0. It is a class C β-lactamase according to BLAST analysis. The coding gene of OtLac was amplified from the genomic DNA of Ochrobactrum tritici. The OtLac was overexpressed in E. coli BL21 (DE3) and purified with Ni2+ column affinity chromatography. The biodegradation ability of penicillin V by OtLac was identified in an in vitro study and analyzed by HPLC. The optimal temperature for OtLac is 32 ℃ and the optimal pH is 7.0. Steady-state kinetics showed that OtLac was highly active against penicillin V with a Km value of 17.86 μM and a kcat value of 25.28 s−1 respectively. Conclusions OtLac demonstrated biodegradation activity towards penicillin V potassium, indicating that OtLac is expected to degrade penicillin V in the future

Design and implementation of a general purpose 2D CAD system

A general purpose 2D CAD system was established by Object-Oriented technology. Key technologies for realizing the system were introduced. The methods for forming shape container, manipulating shape container and constructing graph template library were described in detail. Basic shapes, such as line, rectangle, ellipse, polygon, B-Spline curve and textbox, can be grouped to be a shape container, and the shape containers can also be grouped to form a more complex one. The hierarchy of shape container is a Tree. Hence, to manipulate shape container is to access the container recursively. The Redo and Undo functions were realized by serializing canvas status to temporary files. And all of the canvas statuses were managed by undo-stack and redo-stack. The purposefully formed shape container can be reformed to a graph template, and the graph templates of the same type can be stored as a library. Different graph template library corresponds to different application. Various types of graph template library ensure the generality and flexibility of this system. Experimental results showed that the proposed methods are effective. This system can be applied to a lot of fields, such as construction, machinery and electronics. 漏 2012 ACADEMY PUBLISHER