HEK 293细胞中重组型抗体表达和分泌的监测系统的构建

免疫球蛋白G(Immunoglobulin G,IgG)作为一种十分重要的生物药物,已被广泛应用于多种医学诊断和治疗。为构建高效表达重组抗体的哺乳动物生产菌株,运用可以灵活检测抗体分泌运输的表达细胞株,从而充分理解抗体的折叠、转运及分泌尤为重要。作者在哺乳动物细胞株(HEK 293)中构建了一个稳定表达绿色荧光蛋白(GFP)融合型抗体E-F-HyHEL10的表达系统,可通过流式细胞术检测抗体的分泌运输。此哺乳动物细胞表达系统具有良好的抗体表达和分泌水平,且稳定维持了抗体的功能活性。使用布雷菲德菌素A(brefeldin A)和放线菌酮处理细胞后,来自胞内E-F-HyHEL10的GFP荧光信号与抗体分泌水平呈正相关。结果表明,本研究中构建的抗体表达系统可实现抗体表达、累积和分泌水平的灵活准确监测,未来可应用于哺乳动物细胞中抗体分泌相关因子的筛选。     

Extending the Limits of Backtesting via the ‘Vanishing p’‐Approach

We derive backtests of value‐at‐risk and expected shortfall forecasts for levels that vanish as a function of the sample size n. In the standard case, the level of the forecasts is assumed to be fixed, leading to χ ²‐limiting distributions of the Portmanteau‐type backtests. We show that for levels vanishing at the order of n ^?1/2, Poisson‐type limits arise instead. These mimic key features of the test statistics, such as discreteness. Simulations demonstrate that for forecast levels and sample sizes of practical interest, using the Poisson‐type limits leads to much improved size vis‐à‐vis the standard χ ²‐limits.     

利用PiggyBac转座子系统快速控制GPI锚定蛋白的表达

GPI锚定蛋白的合成是一个发生在内质网中多步骤、多基因参与的过程。PIGK是GPI锚定蛋白转酰胺酶复合物的一个催化亚基,负责把GPI前体转移到蛋白质上。作者在人体胚胎肾细胞(HEK 293)中获得了PIGK敲除的细胞株,敲除PIGK的细胞不能表达GPI锚定蛋白。利用piggyBac(PB)转座子系统,在细胞中重新插入PIGK基因,细胞膜表面的GPI锚定蛋白恢复表达。实验成功构建了HEK293pB-PIGK细胞株并命名为G36,通过引入PB转座酶或FLP重组酶,可以控制GPI锚定蛋白的表达。本系统可以快速调控细胞表面蛋白质的表达并能够用于基础研究和工业应用。     

Volumetric Properties of Chloroalkanes + Amines Mixtures: Theoretical Analysis Using the ERAS-Model

In this study, experimental data of excess molar volumes of {dichloromethane (DCM), or trichloromethane (TCM) + n-butylamine (n-BA), or +s-butylamine (s-BA), or +t-butylamine (t-BA), or +diethylamine (DEA), or +triethylamine (TEA)} mixtures as a function of composition have been used to test the applicability of the extended real associated solution model (ERAS-Model). The values of the excess molar volume were negative for (DCM + t-BA, or +DEA, or +TEA and TCM + n-BA, or +s-BA, or +DEA, or +TEA) mixtures and present sigmoid curves for (DCM + n-BA, or +s-BA) mixtures over the complete mole-fraction range. The agreement between theoretical and experimental results is discussed in terms of cross-association between the components present in the mixtures.     

Development of a fiber-coupled laser-induced breakdown spectroscopy instrument for analysis of underwater debris in a nuclear reactor core

To inspect the post-accident nuclear core reactor of the TEPCO Fukushima Daiichi nuclear power plant (F1-NPP), a transportable fiber-coupled laser-induced breakdown spectroscopy (LIBS) instrument has been developed. The developed LIBS instrument was designed to analyze underwater samples in a high-radiation field by single-pulse breakdown with gas flow or double-pulse breakdown. To check the feasibility of the assembled fiber-coupled LIBS instrument for the analysis of debris material (mixture of the fuel core, fuel cladding, construction material and so on) in the F1-NPP, we investigated the influence of the radiation dose on the optical transmittance of the laser delivery fiber, compared data quality among various LIBS techniques for an underwater sample and studied the feasibility of the fiber-coupled LIBS system in an analysis of the underwater sample of the simulated debris in F1-NPP. In a feasible study conducted by using simulated debris, which was a mixture of CeO₂ (surrogate of UO₂), ZrO₂ and Fe, we selected atomic lines suitable for the analysis of materials, and prepared calibration curves for the component elements. The feasible study has guaranteed that the developed fiber-coupled LIBS system is applicable for analyzing the debris materials in the F1-NPP.     

酿酒酵母中PiggyBac转座子筛选系统的构建

PiggyBac(PB)是来源于粉纹夜蛾(Trichoplusia ni)的TTAA型转座子。PB转座子系统可作为一种插入型突变工具,应用于多种真核细胞中。本研究在酿酒酵母(Saccharomyces cerevisiae)中构建了一个基于PB转座子的筛选系统。系统由插入ADE2基因编码框的PB转座子及由半乳糖启动子调控表达的PB转座酶(PBase)两部分组成。在PBase诱导下,PB转座子可以从原始位点无痕移除并随机插入新的基因位点。PB转座子在转座过程中保持单一拷贝数,在每个突变细胞中只有一个插入位点,并可快速检测突变基因。实验结果表明:所构建的PB转座子筛选系统可应用于酿酒酵母中的基因筛选。     

Biology of angiogenesis in tumors of the gastrointestinal tract

The realization that the growth and spread of tumors are dependent on angiogenesis has created new avenues of research designed to help us to better understand cancer biology and to facilitate the development of new therapeutic strategies. However, the process of angiogenesis consists of multiple, sequential, and interdependent steps with a myriad of positive and negative regulators of angiogenesis being involved. The survival of tumors and thus their metastases are dependent upon the balance of endogenous angiogenic and anti-angiogenic factors such that the outcome favors increased angiogenesis. Several growth factors have been identified that regulate angiogenesis in cancers of the gastrointestinal tract. These include pro-angiogenic factors like vascular endothelial growth factor (VEGF) and anti-angiogenic factors, i.e., thrombospondin. The following review provides a brief overview about the most important factors that are involved in the angiogenic process in tumors derived from colon, stomach, and pancreas. A thorough understanding of the role these factors play in the angiogenic process may lead to the development of novel therapeutic antineoplastic strategies.     

Detecting Tail Risk Differences in Multivariate Time Series

We derive functional central limit theory for tail index estimates in multivariate time series under mild conditions on the extremal dependence between the components. We use this result to also derive convergence results for extreme value‐at‐risk and extreme expected shortfall estimates. This allows us to construct tests for equality of ‘tail risk’ in multivariate data, which can be useful in a number of empirical contexts. In constructing test statistics, we avoid estimating long‐run variances by using self‐normalization. Size and power of the tests for equal ‘tail risk’ are assessed in simulations. An empirical application to exchange returns illustrates the practical usefulness of the tests.