Fusion expression of pedA gene to obtain biologically active pediocin PA-1 in Escherichia coli

Two heterologous expression systems using thioredoxin (trxA) as a gene fusion part in Escherichia coli were developed to produce recombinant pediocin PA-1. Pediocin PA-1 structural gene pedA was isolated from Pediococcus acidilactici PA003 by the method of polymerase chain reaction (PCR), then cloned into vector pET32a(+), and expressed as thioredoxin-PedA fusion protein in the host strain E. coli BL21 (DE3). The fusion protein was in the form of inclusion body and was refolded before purification by nickel-iminodiacetic acid (Ni-IDA) agarose resin column. Biological activity of recombinant pediocin PA-1 was analyzed after cleavage of the fusion protein by enterokinase. Agar diffusion test revealed that 512-arbitrary unit (AU) recombinant pediocin PA-1 was obtained from 1 ml culture medium of E. coli (pPA003PED1) using Listeria monocytogenes as the indicator strain. Thioredoxin-PedA fusion gene was further cloned into pET20b(+). Thioredoxin-PedA fusion protein was detected in both the periplasmic and cytoplasmic spaces. The recombinant pediocin PA-1 from the soluble fraction attained 384 AU from 1 ml culture medium of E. coli (pPA003PED2). Therefore, biologically active pediocin PA-1 could be obtained by these two hybrid gene expression methods.     

Science Letters: A synthetic Toll-like receptor 2 ligand decreases allergic immune responses in a mouse rhinitis model sensitized to mite allergen

It has been proposed that activation of Toll-like receptors (TLRs) plays crucial roles in the polarization of adaptive immune responses. A synthetic Toll-like receptor 2 (TLR2) ligand, Pam3CSK4, has been reported to modulate the balance of Thl/Tn2 responses. We evaluated the modulation effect of Pam3CSK4 on allergic immune response in a mouse rhinitis model sensitized to house dust mite allergen (HDM). Mice were sensitized and challenged with Dermatophagoides farinae allergen (Der f), and then the allergic mice were treated by Pam3CSK4. Nasal allergic symptoms and eosinophils were scored. Der f-specific cytokine responses were examined in the splenocytes and bronchoalveolar lavage fluid (BALF). Serum level of total IgE was also detected. After establishing a mouse allergic rhinitis model with HDM, we have showed that Pam3CSK4 treatment not only ameliorated the nasal allergic symptoms remarkably but also decreased the eosinophils and total inflammation cells in BALF significantly. Analysis of cytokine profile found that' IFN-γ released from either BALF or stimulated splenocytes increased markedly in Pam3CSK4-treated mice, while IL-13 decreased significantly. Moreover, serum level of total IgE was significantly lower in Pam3CSK4-treated mice than in the untreated. Thus, in an allergic rhinitis mouse model developed with HDM, Pam3CSK4 was shown to exhibit an antiallergic effect, indicating its potential application in allergic diseases.     

CO_2激光对小鼠免疫功能影响的实验研究

采用1WCO_2激光器照射小鼠胸腺区及脾区,观察激光照射对血清IgG、溶血素、AFC及LGL的影响．实验结果表明,激光照射组上述免疫指标明显高于对照组（P＜0．01）,由此证明,CO_2激光具有增强免疫细胞活性及促进免疫分子产生的作用．     

Science Letters： A synthetic Toll-like receptor 2 ligand decreases allergic immune responses in a mouse rhinitis model sensitized to mite allergen

It has been proposed that activation of Toll-like receptors (TLRs) plays crucial roles in the polarization of adaptive immune responses. A synthetic Toll-like receptor 2 (TLR2) ligand, Pam3CSK4, has been reported to modulate the balance of Thl/Tn2 responses. We evaluated the modulation effect of Pam3CSK4 on allergic immune response in a mouse rhinitis model sensitized to house dust mite allergen (HDM). Mice were sensitized and challenged with Dermatophagoides farinae allergen (Der f), and then the allergic mice were treated by Pam3CSK4. Nasal allergic symptoms and eosinophils were scored. Der f-specific cytokine responses were examined in the splenocytes and bronchoalveolar lavage fluid (BALF). Serum level of total IgE was also detected. After establishing a mouse allergic rhinitis model with HDM, we have showed that Pam3CSK4 treatment not only ameliorated the nasal allergic symptoms remarkably but also decreased the eosinophils and total inflammation cells in BALF significantly. Analysis of cytokine profile found that' IFN-γ released from either BALF or stimulated splenocytes increased markedly in Pam3CSK4-treated mice, while IL-13 decreased significantly. Moreover, serum level of total IgE was significantly lower in Pam3CSK4-treated mice than in the untreated. Thus, in an allergic rhinitis mouse model developed with HDM, Pam3CSK4 was shown to exhibit an antiallergic effect, indicating its potential application in allergic diseases.     

The balance model of dyslexia and remedial training: an evaluative study

The aim of this study was to test the validity of Bakker's (1983, 1990) theory and treatment paradigm of dyslexia. Twenty-one children (mean age = 9.9 years) categorized as P-type dyslexics (showing accurate but slow and fragmented reading) and 19 children (mean age = 9.7 years) categorized as L-type dyslexics (fast but inaccurate readers) were presented with hemisphere-specific stimulation (HSS) and hemisphere-alluding stimulation (HAS). HSS was produced by presenting words to either the left or the right visual half-field, or to the left or right hand of the participant. HAS training was achieved through the presentation of either semantically/phonetically demanding or perceptually demanding text. Participants were given either a treatment program that was specifically designed for their particular dyslexia subtype, or a program that had been deliberately chosen to be inconsistent with their subtype. Contrary to predictions, participants made gains on all of the reading measures, regardless of the type of treatment given. On the basis of these findings it is suggested that treatment gains made are due to nonspecific training effects and not to the specific nature of Bakker's remedial strategies.     

创建学习型组织应着眼于“细胞”的培育

从20世纪80年代开始，在美国和欧洲一些国家的企业界和管理思想界，出现了研究和推广学习型组织的热潮，并风靡全球。近几年我们国家的部分企业也在推广应用这一理论，但效果褒贬不一，就国有企业而言，客观地说，运用这种管理的整体效果并不尽如人意，使这一理论的推广运用出现了严重的智障，究其原因：     

抑癌基因PTEN载体构建及在LOVO细胞中的表达

目的:构建抑癌基因PTEN的表达载体并在LOVO细胞中表达。方法:从人外周血中提取总RNA,通过RT-PCR扩增出PTEN基因片段,将PTEN基因连入pLenti6/V5载体。测序鉴定后,经脂质体转染入LOVO细胞,对细胞株进行RT-PCR和Western blot检测。结果:DNA测序证实pLenti6/V5-PTEN表达载体为阳性克隆;该表达载体转染LOVO细胞后上调了PTEN mRNA和蛋白的表达。结论:成功构建了pLen-ti6/V5-PTEN表达载体,为进一步研究PTEN在LOVO细胞中的功能奠定了基础。     

数列an=(1+1/n)n极限存在的一种证明方法

运用平均值不等式证明了数列an=(1+1n) n 的极限存在性 ,并且得到有界性比较强的结果。     

食道癌和胃癌组织中MDM2基因蛋白表达的研究

为探讨MDM2基因蛋白在胃、食道癌中表达的特点。我们利用SABC免疫组织化学方法,检测了69例食道癌和胃癌标本。结果表明:MDM2总阳性率为56.52％,在食道癌中阳性率为63.47％,胃癌中阳性率为46.42％;在高分化癌组织中阳性率为77.78％;低分化癌阳性率为29.41％;两者差异有显著性(P<0.05)。文中对MDM2基因在以上两种癌组织中表达的意义进行了讨论。     

Cultivating Native American scientists: an application of an Indigenous model to an undergraduate research experience

Cultural Studies of Science Education - With growing evidence demonstrating the impact of undergraduate research experiences on educational persistence, efforts are currently being made to expand...     

Speaking L1 in an L2 World

Why do some Chinese students choose to speak their L1 at home when they are spending time, effort, and money to learn a new language and when they have been told time and again by their teachers to "speak as much English as possible"? The compatibility hypothesis (see Tharp, 1994) predicts school success for Chinese children, because their teachinglearning modes match with U.S. education practices. This may also be true of Chinese adults at school (see Park, 1997), but I would like to suggest that the typical home practices of Chinese     

Guidance in eastern Europe: from ideological formation to an emerging service model

This article analyzes major changes that have occurred in east-European guidance over the past decades. The emphasis has gradually shifted from purely ideological concerns to an interest in serving the needs of individuals. Whereas in the initial stage structural uniformity was of great importance, current views accept a degree of diversification in guidance services on the basis of regional needs and sociocultural traditions. Tangible differences seem to exist between guidance strategies that are prevalent in the Soviet Union and in certain areas of east-central Europe.University of South Florida     

骨髓间充质干细胞防治心肌细胞凋亡的Bcl-2和Bax蛋白表达研究

论文通过文献资料法、逻辑分析法等对骨髓间充质干细胞作用于心肌细胞凋亡应用,以及心肌细胞凋亡与Bcl-2和Bax蛋白表达的关系进行研究,旨在探讨骨髓间充质干细胞调控Bcl-2、Bax基因蛋白表达的方式对心肌细胞凋亡的作用机制。研究发现,心肌细胞凋亡与Bcl-2、Bax基因蛋白的表达存在高度相关性,通过调控Bcl-2、Bax的基因表达能够在一定程度上防止心肌细胞凋亡的发生与发展,而骨髓间充质干细胞则可以通过自身诱导分化的特性有效的调控Bcl-2和Bax蛋白的表达,使损伤后的心肌功能得到改善。     

IK4基因突变体与其逆转录病毒载体的构建及在白血病细胞中的表达

对造血调控中发挥重要作用的IKAROS基因亚型IK4进行突变,并构建重组逆转录病毒表达载体及使其在白血病细胞中表达。采用重叠延伸PCR定点突变技术,成功构建了4个IK4单突变或多突变突变体。将这4个突变体克隆至Pmscvpuro逆转录病毒载体中,构建重组蛋白表达载体。基因测序验证突变序列正确后,将重组逆转录病毒载体与病毒包装质粒VSVG、Gag-Pol共同感染293T细胞,过滤收集病毒上清,将病毒上清转染白血病NB4细胞。用Puromycin对细胞进行筛选,并通过Western印迹法对突变体表达细胞系进行验证。通过重叠延伸PCR法成功构建了4个IK4的定点单突变和定点多突变体,利用逆转录病毒介导的转染方法使IK4的4个突变体在白血病细胞中成功稳定表达,为后续的功能和机制的研究奠定了基础。