Molecular cloning,expression, and immobilization of glutamate decarboxylase from Lactobacillus fermentum YS2

BackgroundGABA (γ-aminobutyric acid) is a four-carbon nonprotein amino acid that has hypotensive, diuretic, and tranquilizing properties. Glutamate decarboxylase (GAD) is the key enzyme to generate GABA. A simple and economical method of preparing and immobilizing GAD would be helpful for GABA production. In this study, the GAD from Lactobacillus fermentum YS2 was expressed under the control of a stress-inducible promoter and was purified and immobilized in a fusion form, and its reusability was investigated.ResultsThe fusion protein CBM-GAD was expressed in Escherichia coli DH5α carrying pCROCB-gadB, which contained promoter P_rpoS, cbm3 (family 3 carbohydrate-binding module from Clostridium thermocellum) coding sequence, the gadB gene from L. fermentum YS2 coding for GAD, and the T7 terminator. After a one-step purification of CBM-GAD using regenerated amorphous cellulose (RAC) as an adsorbent, SDS-PAGE analysis revealed a clear band of 71 kDa; the specific activity of the purified fusion protein CBM-GAD reached 83.6 ± 0.7 U·mg^-1. After adsorption onto RAC, the immobilized GAD with CBM3 tag was repeatedly used for GABA synthesis. The protein-binding capacity of RAC was 174 ± 8 mg·g^-1. The immobilized CBM-GAD could repeatedly catalyze GABA synthesis, and 8% of the initial activities was retained after 10 uses. We tested the conversion of monosodium glutamate to GABA by the immobilized enzyme; the yield reached 5.15 g/L and the productivity reached 3.09 g/L·h.ConclusionsRAC could be used as an adsorbent in one-step purification and immobilization of CBM-GAD, and the immobilized enzyme could be repeatedly used to catalyze the conversion of glutamate to GABA.     

大豆花叶病毒杭州分离物基因组全序列测定及其结构分析

测定了大豆花叶病毒杭州分离物（SMV－HZ）的基因组全序列。该病毒基因组全长9588个核苷酸，3‘末端具poly(A)尾，包含单一开读框，编码一个350.07kD的多聚蛋白。基因组全序列与美国SMV G2、G7、N株系及我国黄淮5号株系（Y5）的核苷酸同一性分别为93％、93％、94％和96％。多聚蛋白酶解后产生马铃薯Y病毒属典型的10成熟蛋白。SMV－YZ与G2、G7、N的不同成熟蛋白间的氨基酸同一性为89％－100％；SMV－HZ与Y5的不同成熟蛋白间氨基酸同一性则较高，达97％－100％。多重分析显示了SMV－HZ与G2、G7、N、Y5之间的序旬差异，G2、G7的P1蛋白氨基酸序列明显不同于其他株系，对SMV－HZ与我国其他株系。对SMV－HZ与我国其他分离物也进行了序列比较，对CP蛋白氨基酸序列的系统进化树分析表明SMV－HZ与BJ分离物的亲缘性最高。     

Characterization of a microflow cytometer with an integrated three-dimensional optofluidic lens system

Flow cytometry is a standard analytical method in cell biology and clinical diagnostics and is widely distributed for the experimental investigation of microparticle characteristics. In this work, the design, realization, and measurement results of a novel planar optofluidic flow cytometric device with an integrated three-dimensional (3D) adjustable optofluidic lens system for forward-scattering∕extinction-based biochemical analysis fabricated by silicon micromachining are presented. To our knowledge, this is the first planar cytometric system with the ability to focus light three-dimensionally on cells∕particles by the application of fluidic lenses. The single layer microfluidic platform enables versatile 3D hydrodynamic sample focusing to an arbitrary position in the channel and incorporates integrated fiber grooves for the insertion of glass fibers. To confirm the fluid dynamics and raytracing simulations and to characterize the sensor, different cell lines and sets of microparticles were investigated by detecting the extinction (axial light loss) signal, demonstrating the high sensitivity and sample discrimination capability of this analysis system. The unique features of this planar microdevice enable new biotechnological analysis techniques due to the highly increased sensitivity.     

Toward a Longitudinal Model of e-Commerce: Environmental,Technological, and Organizational Drivers of B2C Adoption

Despite the important benefits for firms of commercial initiatives on the Internet, e-commerce is still an emerging distribution channel, even in developed countries. Thus, more needs to be known about the mechanisms affecting its development. A large number of works have studied firms' e-commerce adoption from technological, intraorganizational, institutional, or other specific perspectives, but there is a need for adequately tested integrative frameworks. Hence, this work proposes and tests a model of firms' business-to-consumer (called B2C) e-commerce adoption that is founded on a holistic vision of the phenomenon. With this integrative approach, the authors analyze the joint influence of environmental, technological, and organizational factors; moreover, they evaluate this effect over time. Using various representative Spanish data sets covering the period 1996–2005, the findings demonstrate the suitability of the holistic framework. Likewise, some lessons are learned from the analysis of the key building blocks. In particular, the current study provides evidence for the debate about the effect of competitive pressure, since the findings show that competitive pressure disincentivizes e-commerce adoption in the long term. The results also show that the development or enrichment of the consumers' consumption patterns, the technological readiness of the market forces, the firm's global scope, and its competences in innovation continuously favor e-commerce adoption.     

Effect of yoga training on plasma lipid profile,R.B.C. membrane lipid peroxidation and Na+K+ ATPase activity in patients of essential hypertension

We conducted a controlled study on effect of selected yoga practive in the control and management of 50 cases of essential hypertension and equal number of healthy (nonhypertensive) controls. Free radical cellular damage is considered to be the underlying common biological factor in essential hypertension. We, therefore, investigated lipid profile lipid peroxidation and Na⁺K⁺ ATPase activities of plasma membrane of subjects with essential hypertension. It was found that hypertensive subjects had an elevated lipid peroxidation and decreased Na⁺K⁺ ATPase activity in plasma membrane as compared to normotensive healthy controls, the specific yoga training protocol which was administered not only helped to decrease blood pressure but also retard the progression of ceellular damage due to free radicals.     

墨脱毛兰，一个可能的“异常整齐花”型，兼论兰科中“异常整齐花”现象

新种墨脱毛兰可能是足茎毛兰的“异常整齐花”型。  “异常整齐花”现象在兰科中时     有所见，在不同分类群中情况各异，至今尚未见系统的研究。本文认为辐射对称花被是兰科的     正常特征之一，主要见于原始的种类和少数进化的种类，也不同程度地存在于“异常整齐花”实     体中。具辐射对称花被的兰科植物大多数不是“异常整齐花”型，判断时要参酌其他特点，持慎     重态度。兰科“异常整齐花”有两种情况，一是异常型，亦即正常植株中仅偶见“异常整齐花”，     或同一个种可同时产生“异常整齐花”植株与正常植株，两者并存。另一种情况是正常型，亦即     只产生“异常整齐花”，而无正常的两侧对称花。后者意味着在进化过程中的一种飞跃，即形成     了新植物。对此最好作为独立的种处理，特别是在它的来源还不清楚的情况下更是如此。目     前所认为的一些所谓“异常整齐花”实体，大都是推测而已，其中有些或许在将来会被证明为正    常的、原始的植物。     

球隔麻属——荨麻科一新属，兼论荨麻科的柱头

本文描述了分布于中国西藏东南部的荨麻科的一新亚族——球隔麻亚族，一新属—— 球隔麻属及其模式种球隔麻。它被认为是苧麻族较原始的一个类群。其环状柱头及球形药隔 在荨麻科中至今还是首次发现。  本文还论述了荨麻科植物的柱头特征、类型及其分类学意义，并探讨了它们的演化趋势。     

Experimental study of the critical speed response,of a jeffcott rotor with acceleration

A small, lightly damped rotor (ζ=0.0088) was experimentally tested for a variety of acceleration and deceleration rates. In each case, the amplitude response was plotted as a function of operating speed, with the acceleration rate considered. In each case the results are compared with theoretical predictions. The results agree within 6% at the peak response. The results of the analysis indicate that for high acceleration rates the critical amplitude response may be reduced by a factor of four or more. The frequency of the effective critical speed may be shifted by up to 20%. Furthermore, a beating frequency was observed in the amplitude data after the rotor had passed through the critical speed. This phenomenon is shown to be the vector sum of a synchronous component of amplitude and a nonsynchronous transient component (at the critical speed). The transient nonsynchronous component is shown explicitly via electronic band-pass filtering, as is the forced response component. Finally, spectral analyses were performed over a range of operating speeds, yielding waterfall diagrams and further verification of the existence of the two components.