Establishment of a production process for a novel vaccine candidate against Lawsonia intracellularis

BackgroundLawsonia intracellularis remains a problem for the swine industry worldwide. Previously, we designed and obtained a vaccine candidate against this pathogen based on the chimeric proteins: OMP1c, OMP2c, and INVASc. These proteins formed inclusion bodies when expressed in E. coli, which induced humoral and cellular immune responses in vaccinated pigs. Also, protection was demonstrated after the challenge. In this study, we established a production process to increase the yields of the three antigens as a vaccine candidate.ResultsBatch and fed-batch fermentations were evaluated in different culture conditions using a 2 L bioreactor. A fed-batch culture with a modified Terrific broth medium containing glucose instead of glycerol, and induced with 0.75 mM IPTG at 8 h of culture (11 g/L of biomass) raised the volumetric yield to 627.1 mg/L. Under these culture conditions, plasmid-bearing cells increased by 10% at the induction time. High efficiency in cell disruption was obtained at passage six using a high-pressure homogenizer and a bead mill. The total antigen recovery was 64% (400 mg/L), with a purity degree of 70%. The antigens retained their immunogenicity in pigs, inducing high antibody titers.ConclusionsConsidering that the antigen production process allowed an increment of more than 70-fold, this methodology constitutes a crucial step in the production of this vaccine candidate against L. intracellularis.How to cite: Salazar S, Gutiérrez N, Sánchez O, et al. Establishment of a production process for a novel vaccine candidate against Lawsonia intracellularis. Electron J Biotechnol 2021.https://doi.org/10.1016/j.ejbt.2021.01.002     

Rhetoric, power and legitimacy: a critical analysis of the public policy disputes surrounding stem cell research in Australia (2005-6)

In December 2006, the Australian Parliament liberalized regulation governing stem cell research. This decision and preceding legislative review generated considerable public debate, which centred on objections to the deliberate creation and destruction of human embryos for research purposes. This paper draws on qualitative research conducted on the public debate surrounding this policy episode. The aim of this research was to examine how science and scientific knowledge are mobilized by participants in these debates to support their arguments. Data were collected from 109 newspaper opinion editorials as well as 23 in-depth interviews and examined using qualitative content and thematic analysis. Results of this analysis depict science as a rhetorical, moral and political resource that provides opportunities for participants to gain legitimacy, negotiate meaning and assert authority in the public domain. The mobilization of science in public discourse is discussed along with suggestions that are aimed at encouraging greater transparency and inclusiveness in public debates around contested science and emergent technologies.     

打造合作课堂的温暖驿站

新课程改革已经拉开序幕,老师的培训活动一直都紧锣密鼓地开展,新课程改革的新观念与新思维让老师们如沐春风,我们渴望改革,渴望让学生减负,渴望让学生学得主动,而新课程的组成部分之一就是让学生学会合作,这门课在学生成长过程中有着教科书无可替代的作用。本文探讨如何利用积极心理学组织高效合作课堂的思想动员、分组、小组建设与课堂评价的各项工作,为学生打造合作课堂的温暖驿站。     

基于S7-200的乳化炸药生产线超限智能报警系统

据乳化炸药生产线的现状及存在的安全问题,设计了一种基于PLC的乳化炸药生产线超限和智能报警系统.该系统可实现乳化炸药生产线的温度、压力、螺杆泵电流和转速等参数的自动采集以及生产线和监测中心的声光报警,并从软件和硬件系统设计方面进行详细阐述.     

石英晶体微天平-环介导快速检测大肠杆菌O157特异基因方法的建立

目的:建立原位石英晶体微天平(QCM)-环介导恒温扩增(LAMP)快速检测大肠杆菌O157特异基因的方法。方法:在环介导恒温核酸扩增(LAMP)技术平台引入石英晶体微天平(QCM)技术,采用巯基化试剂分子组装方法,将LAMP反应体系中的4个引物之一固定于QCM电极上,在安装所述电极的QCM检测池中配置O157 LAMP反应体系进行环介导恒温核酸扩增,用QCM仪器在线检测频率变化,判断LAMP反应是否发生,进而判断体系中是否存在O157特异基因。结论:该方法检测O157特异基因特异性强、灵敏度高,并且操作简便,有望发展成为快速检测O157特异基因的有效手段。     

中药产业发展与中药技术科学的建立

中药学科知识体系结构分为基础科学、技术科学和工程技术三个层次,并通过整体观、阴阳学说与哲学层次相连接.中药技术科学有中药炮制学、中药学和方剂学,中药工程技术包括生产工艺理论、生产共性技术和中药使用标准化理论三方面.中药技术科学的发展水平,直接影响着中医药基础科学成果向工程技术转化的速度和效率,加大技术科学层次人力资源投入,必然将推进中药产业现代化和国际化进程.     

Single cell oil production by a novel yeast Trichosporon mycotoxinivorans for complete and ecofriendly valorization of paddy straw

BackgroundOleaginous yeasts can be grown on different carbon sources, including lignocellulosic hydrolysate containing a mixture of glucose and xylose. However, not all yeast strains can utilize both the sugars for lipogenesis. Therefore, in this study, efforts were made to isolate dual sugar-utilizing oleaginous yeasts from different sources.ResultsA total of eleven isolates were obtained, which were screened for their ability to utilize various carbohydrates for lipogenesis. One promising yeast isolate Trichosporon mycotoxinivorans S2 was selected based on its capability to use a mixture of glucose and xylose and produce 44.86 ± 4.03% lipids, as well as its tolerance to fermentation inhibitors. In order to identify an inexpensive source of sugars, nondetoxified paddy straw hydrolysate (saccharified with cellulase), supplemented with 0.05% yeast extract, 0.18% peptone, and 0.04% MgSO₄ was used for growth of the yeast, resulting in a yield of 5.17 g L⁻¹ lipids with conversion productivity of 0.06 g L⁻¹ h⁻¹. Optimization of the levels of yeast extract, peptone, and MgSO₄ for maximizing lipid production using Box–Behnken design led to an increase in lipid yield by 41.59%. FAME analysis of single cell oil revealed oleic acid (30.84%), palmitic acid (18.28%), and stearic acid (17.64%) as the major fatty acids.ConclusionThe fatty acid profile illustrates the potential of T. mycotoxinivorans S2 to produce single cell oil as a feedstock for biodiesel. Therefore, the present study also indicated the potential of selected yeast to develop a zero-waste process for the complete valorization of paddy straw hydrolysate without detoxification.How to cite: Sagia S, Sharma A, Singh S, et al. Single cell oil production by a novel yeast Trichosporon mycotoxinivorans for complete and ecofriendly valorization of paddy straw. Electronic Journal of Biotechnology 2020;44. https://doi.org/10.1016/j.ejbt.2020.01.009.     

Polyelectrolyte multilayer surface functionalization of poly(dimethylsiloxane) (PDMS) for reduction of yeast cell adhesion in microfluidic devices

Polyelectrolyte multilayers (PEMs) based on the combinations poly(diallyldimethylammonium chloride)∕poly(acrylic acid) (PDADMAC∕PAA) and poly(allylamine hydrochloride)∕PAA (PAH∕PAA) were adsorbed on poly(dimethylsiloxane) (PDMS) and tested for nonspecific surface attachment of hydrophobic yeast cells using a parallel plate flow chamber. A custom-made graft copolymer containing poly(ethylene glycol) (PEG) side chains (PAA-g-PEG) was additionally adsorbed on the PEMs as a terminal layer. A suitable PEM modification effectively decreased the adhesion strength of Saccharomyces cerevisiae DSM 2155 to the channel walls. However, a further decrease in initial cell attachment and adhesion strength was observed after adsorption of PAA-g-PEG copolymer onto PEMs from aqueous solution. The results demonstrate that a facile layer-by-layer surface functionalization from aqueous solutions can be successfully applied to reduce cell adhesion strength of S. cerevisiae by at least two orders of magnitude compared to bare PDMS. Therefore, this method is potentially suitable to promote planktonic growth inside capped PDMS-based microfluidic devices if the PEM deposition is completed by a dynamic flow-through process.     

科学网络中的行动者及其影响因素——以人类胚胎干细胞研究为例

基于人类胚胎干细胞科学研究的发展情况,运用"行动者一网络"理论模式的独特视角,建构了行动者网络并界定了网络中的各类行动者,分析了人类胚胎干细胞研究与发展的影响因素,进一步提出了相应的针对性策略,由此深化认识了行动者网络理论在人类胚胎干细胞研究中的理论和现实意义。     

探索建立大学生党员质量保障体系研究

高校是选拔和培养青年马克思主义者和社会主义事业接班人的摇篮,提高大学生党员的发展质量是高校党建工作的重要内容。在大学生党员发展和管理的过程中,应从思想教育、制度保证、程序严格、注重后期教育等几个方面探索构建大学生党员质量保障机制。只有这样才能保持高校党建工作的生机与活力,永葆党员队伍的先进性。     

建立健全高校大学生思想稳定工作机制研究

本文针对新形势下高校学生思想稳定工作出现的新情况、新问题,结合实际情况,提出了建立健全高校学生思想稳定工作的长效机制的一些想法和意见。     

建立地方高校MOOC教师发展的需求模型

慕课作为教育信息化发展阶段的典型案例,虽然直接作用于学生,但也涉及学校和教师,地方高校和教师都应采取相应措施推动慕课资源进校园,以维持学校、教师和学生的三角稳定关系。该文从系统论的角度分析如何建立地方高校教师发展的需求模型。该需求模型建议教师提升自身混合式教学的能力,增加技术知识,发展教学和学术科研能力。该需求模型可以解决学生在慕课学习中遇到的困难,发挥教师的作用,提升信息技术背景下教师的能力。     

On the influence of the architecture of poly(ethylene glycol)-based thermoresponsive polymers on cell adhesion

Thermoresponsive polymer surface coatings are a promising tool for cell culture applications. They allow for a mild way of cell detachment that preserves the activity of membrane proteins—a prerequisite for reliable cell analysis. To enlarge the application range of these coatings to cells with different adhesion properties, we synthesized various novel poly(ethylene glycol)-based thermoresponsive polymers and describe how (i) their chemical structure and (ii) their surface density affect their efficiency. In order to quantify the influence of both factors, the time for cell spreading and rounding efficiency were observed. As a result, efficiency of cell rounding, which is closely correlated to cell detachment, is less affected by both factors than the time needed for cell spreading. This time can effectively be adjusted by the molecular architecture which includes the length of the polymer backbone and the side chains. Based on this work, recommendations are given for future optimization of functionality of thermoresponsive polymer coatings for cell culture applications.     

基因组学研究领域的两个重要成就——家蚕基因组框架图和家鸡基因组多态性图谱的绘制

"家蚕基因组框架图和家鸡基因组多态性图谱的绘制"是于2003年启动的两个重要物种的基因组学计划。主要包括"家蚕基因组框架图的绘制"及"家鸡基因组多态性     

Recent experience of the application of a commercial data base management system (ADABAS) to a scientific data bank (ECDIN)

The ECDIN (Environmental Chemicals Data and Information Network) project started in 1973. During the pilot phase of operation the feasibility of the system was demonstrated using a data base of 4000 compounds and the SIMAS information retrieval system. It was quickly realised that for ECDIN data management was as important as information retrieval and in November 1977, after a study of available software, the ADABAS data base management system was installed at JRC Ispra for ECDIN and other JRC data banks. A design exercise for the ECDIN ADABAS data base has been completed and parts of the existing ECDIN data base have been converted to the new system. The problems encountered and the solutions adopted are discussed. The user interface to ECDIN is still under development. When fully operational ECDIN will be available through EURONET to both casual and specialist users and, in consequence, at least two levels of user interface will be required: (a) a user friendly conversational language designed for the casual user and capable of dealing with the more common types of question, (b) a sophisticated query language capable of answering the more difficult questions, producing “one-off” reports and probably requiring both a specialist knowledge of the data base and a programmer oriented background. The first tentative steps in this direction are described.     

基质固相分散(MSPD)用ODS的合成与表征

本文主要以经酸处理的大粒径无定形硅胶为基质,让其在有机溶剂无水甲苯里和十八烷基三氯硅烷(octadecyltrichlorosilane,OTS)发生硅烷化反应,三甲基氯硅烷(trimethylchlorosilane,TMCS)进行封端处理,合成十八烷基硅烷(octadecylsilan,ODS)键合相;并用傅立叶变换红外吸收光谱(Fourier transform infrared spectroscopy,FTIR)表征合成产物结构组成,将其装填成柱后用高效液相色谱仪(High performanceliquid chromatography,HPLC)对其予以色谱性能评价。     

高领藓属(高领藓科)一新种——卷尖高领藓

描述了高领藓属Glyphomitrium(高领藓科Glyphomitriaceae)一新种——卷尖高领藓G. tortifolium Y. Jia, M. Z. Wang & Y. Liu。它因体形大,叶片卷曲和雌苞叶具长尾尖而与G. elatum Takaki相似,但是又因它植物体更大,叶片狭披针形,雌苞叶在骤尖基部两侧略凹陷而区别于后者。