硅在植物体内的分布和吸收及其在病害逆境胁迫中的抗性作用

硅在地壳中含量位居第二位,尽管还没有被列为植物生长的必需营养元素,但它在促进植物生长发育和营养吸收、提高植物对非生物逆境胁迫和生物逆境胁迫的抗性等方面都具有重要作用。综述了近些年来国内外关于硅在植物体内的分布、吸收及其生理效应,重点介绍了硅在病害逆境胁迫中的抗性作用机理。高等植物以单硅酸[Si(OH)4]的形式吸收硅,存在硅的主动吸收和被动吸收机制。硅主要沉积在叶片及叶鞘表皮细胞,形成硅化细胞和角质-硅双层结构,能增强寄主植物细胞壁的机械强度和稳固性,从而延缓和抵御病菌的侵入和扩展。更多的证据表明,硅处理能增加植物叶片保护酶(过氧化物酶、多酚氧化酶、苯丙氨酸解氨酶等)活性和诱导寄主产生次生代谢抗性物质(如植保素、多酚类化合物、木质素),从而激活植物的防御系统,增强对病原菌的抵抗能力。分子水平上的研究显示,硅能诱导与植物防御机制相关的基因表达,参与抗病信号分子(如水杨酸、茉莉酸和乙烯)在信号传导中的作用。     

用人工神经网络方法估计Ligistic方程参数

本文提出Logistic方程参数优化估计的人工神经网络方法,并选取一组标样进行具体尝试。结果表明,用这种方法估计Logistic方程参数效果极好。     

Intratumoral heterogeneity determines discordant results of diagnostic tests for human epidermal growth factor receptor (HER) 2 in gastric cancer specimens

Accurate assessment of human epidermal growth factor receptor (HER) 2 is essential for efficient selection of patients who may benefit from therapies targeting this surface receptor (e.g., trastuzumab). Intratumoral heterogeneity of HER2 expression may potentially contribute to inaccurate assessment of HER2 status. To clarify intratumoral heterogeneity of HER2 expression and its potential clinical impact on assessment of HER2 status, we analyzed 148 endoscopic biopsy specimens and 117 excisional tumor specimens collected from 148 patients with primary gastric cancer. Specifically, we assessed HER2 protein overexpression and gene amplification using, respectively, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). There were 28 IHC-positive cases and 25 FISH-positive cases among these 148 patients. Heterogeneous HER2 protein expression was demonstrated in 23 of 29 (79.3%) IHC-positive cases, while gene expression heterogeneity was found in 11 of 25 (44.0%) FISH-positive cases. Intratumoral heterogeneity was the main reason of discordant results between IHC and FISH or between endoscopic biopsy and excisional tumor specimens. The clinical significance and impact of intratumoral HER2 expression heterogeneity on treatment outcome in gastric cancer require further studies.     

太湖大型底栖动物群落结构及多样性

为揭示现阶段太湖大型底栖动物群落现状及其对生态环境变化的响应, 于2007年2月至2008年11月对太湖大型底栖动物进行为期两周年的季度调查。30个采样点共记录底栖动物3门7纲19科40种, 底栖动物平均密度和生物量空间差异较大, 平均密度高值出现在梅梁湾、竺山湾及河口, 主要为寡毛纲颤蚓类; 平均生物量高值出现在贡湖湾、西湖区、东太湖和东部湖湾, 主要为软体动物。霍甫水丝蚓(Limnodrilus hoffmeisteri)、中华河蚓(Rhyacodrilus sinicus)、河蚬(Corbicula fluminea)、铜锈环棱螺(Bellamya aeruginosa)、中国长足摇蚊(Tanypus chinensis)和钩虾属一种(Gammarus sp.)是现阶段太湖大型底栖动物的优势种。聚类分析将30个采样点分成3组, 相似性分析检验表明各聚类组大型底栖动物群落具有显著差异(P<0.05)。多样性分析结果表明, 东太湖和东部湖湾物种多样性、丰富度和均匀度最高, 优势种为腹足纲螺类; 梅梁湾、竺山湾及河口多样性最低、密度最高, 霍甫水丝蚓和中华河蚓在该区占据绝对优势; 贡湖湾、湖心和西湖区多样性处于中等水平, 其优势种为河蚬。研究结果表明营养水平、底质类型以及水生植被的分布是决定太湖大型底栖动物群落结构及多样性的关键因子。     

Ad-sTNFRI-IgGFc腺病毒载体的构建及其转染人气道平滑肌细胞

TNF-a是一种具有广泛生物学活性的前炎症细胞因子, 参与哮喘整个病理生理过程。可溶性肿瘤坏死因子受体(sTNFR)可以拮抗肿瘤坏死因子活性, 已被用来治疗与TNF相关的炎性疾病。将sTNFRI-IgGFc基因插入腺病毒穿梭质粒pDC316, 与辅助质粒pBHGloxΔE1, 3Cre共转染HEK293细胞, 重组产生Ad-sTNFRI-IgGFc, PCR鉴定毒种正确后, 进行扩增、纯化和滴度测定, 转染人气道平滑肌细胞, 利用RT-PCR、免疫组化方法, 流式细胞仪, ELISA检测转染后细胞中sTNFRI-IgGFc的转录和表达。实验结果证明成功构建了Ad-sTNFRI-IgGFc腺病毒载体, 感染性滴度达3×1010 TCID50/mL, 200 moi转染气道平滑肌细胞阳性率达99.32%, 转染后气道平滑肌细胞在mRNA和蛋白水平均有sTNFRI-IgGFc表达。转染上清稀释64倍后仍对TNF有拮抗活性。为将表达sTNFRI-IgGFc腺病毒基因治疗哮喘的实验研究提供了基础。     

Silicon-Mediated Tomato Resistance Against Ralstonia solanacearum is Associated with Modification of Soil Microbial Community Structure and Activity

Bacterial wilt caused by Ralstonia solanacearum is a serious soil-borne disease of Solanaceae crops. In this study, the soil microbial effects of silicon-induced tomato resistance against R. solanacearum were investigated through pot experiment. The results showed that exogenous 2.0 mM Si treatment reduced the disease index of bacterial wilt by 19.18 % to 52.7 % compared with non-Si-treated plants. The uptake of Si was significantly increased in the Si-treated tomato plants, where the Si content was higher in the roots than that in the shoots. R. solanacearum inoculation resulted in a significant increase of soil urease activity and reduction of soil sucrase activity, but had no effects on soil acid phosphatase activity. Si supply significantly increased soil urease and soil acid phosphatase activity under pathogen-inoculated conditions. Compared with the non-inoculated treatment, R. solanacearum infection significantly reduced the amount of soil bacteria and actinomycetes by 52.5 % and 16.5 %, respectively, but increased the ratio of soil fungi/soil bacteria by 93.6 %. After R. solanacearum inoculation, Si amendments significantly increased the amount of soil bacteria and actinomycetes and reduced soil fungi/soil bacteria ratio by 53.6 %. The results suggested that Si amendment is an effective approach to control R. solanacearum. Moreover, Si-mediated resistance in tomato against R. solanacearum is associated with the changes of soil microorganism amount and soil enzyme activity.     

芘降解质粒提取方法的研究

采用碱裂解法、化学改良方法、CTAB法、酚氯法等4种方法提取从泉州红树林沉积物中筛选出多环芳烃降解菌群YL的质粒,并分别转化至大肠杆菌感受态细胞,然后采用富集筛选的手段,最终确立最佳方案得到一组质粒转化菌群.该转化菌群可以利用芘作为其生长的惟一碳源和能源,并能在21 d内将50 mg·L-1的芘降解85.69%.而受体菌E.coli DH5α的芘降解率仅为2.006%.由此可以证明,降解质粒已成功转化进宿主细胞,并发挥降解作用.YL的质粒含有降解芘的基因.     

Cloned pig fetuses exhibit fatty acid deficiency from impaired placental transport

Cloned pig fetuses produced by somatic cell nuclear transfer show a high incidence of erroneous development in the uteri of surrogate mothers. The mechanisms underlying the abnormal intrauterine development of cloned pig fetuses are poorly understood. This study aimed to explore the potential causes of the aberrant development of cloned pig fetuses. The levels of numerous fatty acids in allantoic ?uid and muscle tissue were lower in cloned pig fetuses than in artificial insemination‐generated pig fetuses, thereby suggesting that cloned pig fetuses underwent fatty acid deficiency. Cloned pig fetuses also displayed trophoblast hypoplasia and a reduced expression of placental fatty acid transport protein 4 (FATP4), which is the predominant FATP family member expressed in porcine placentas. This result suggested that the placental fatty acid transport functions were impaired in cloned pig fetuses, possibly causing fatty acid deficiency in cloned pig fetuses. The present study provides useful information in elucidating the mechanisms underlying the abnormal development of cloned pig fetuses.     

Reconstitution of the peptidoglycan cytoplasmic precursor biosynthetic pathway in cell-free system and rapid screening of antisense oligonucleotides for Mur enzymes

Bacterial peptidoglycan is the cell wall component responsible for various biological activities. Its cytoplasmic precursor UDP-N-acetylmuramyl pentapeptide is biosynthesized by the first six enzymes of peptidoglycan synthetic pathways (Mur enzymes), which are all proved to be important targets for antibiotic screening. In our present work, the genes encoding Mur enzymes from Escherichia coli were co-expressed in the cell-free protein synthesis (CFPS) system, and the activities of Mur enzymes derived from CFPS system were validated by the synthesis of the final product UDP-N-acetylmuramyl pentapeptide. Then this in vitro reconstituted Mur biosynthetic pathway was used to screen a panel of specific antisense oligonucleotides for MurA and MurB. The selected oligonucleotides were proved to eliminate the expression of Mur enzymes, and thus inhibit the Mur biosynthetic pathway. The present work not only developed a rapid method to reconstruct and regulate a biosynthetic pathway in vitro, but also may provide insight into the development of novel antibiotics targeting on peptidoglycan biosynthetic pathway.     

残缺类囊体膜与嵴膜小囊的融合膜结构观察

观察了菠菜叶绿体类囊体膜与残缺膜的表面结构及鼠肝线粒体嵴膜小囊在制备过程中的生成过程,证明了嵴膜小囊可有两种,F_1在膜外侧或膜内侧,它们都可与残缺膜组成镶嵌膜,进行光下磷酸化功能。而F_1在膜外侧的嵴膜小囊与残缺膜的嵌合膜活力更高。