定点突变阻止金黄色葡萄球菌α-溶血素溶血活性

金黄色葡萄球菌分泌的α-溶血素是导致肺炎的重要致病因子。为进一步研究金黄色葡萄球菌α-溶血素(α-hla)的分子致病机理以及对其进行免疫预防,对α-hla第35位氨基酸进行了定点突变。用聚合酶链式反应(PCR)技术,从S.aureus wood46株基因组中扩增出α-hla基因,再利用重叠延伸PCR技术,将第35位带正电荷的组氨酸(密码子为CAC)突变为非极性的亮氨酸(密码子为CTC)。hlaH35L基因测序结果显示第35位的组氨酸突变为亮氨酸,构建的重组表达质粒pET-28a-c(+)/hla和pET-28a-c(+)/hlaH35L在E.coli BL21(DE3)中得到表达,重组蛋白α-Hla及hlaH35L大小均为33.4 kDa,α-Hla引起兔红细胞溶血,hlaH35L未引起兔红细胞溶血。成功表达并获得了失去溶血毒性的重组蛋白hlaH35L。     

α-乙酰乳酸脱羧酶基因在枯草芽孢杆菌中的整合型表达

α-乙酰乳酸脱羧酶在啤酒生产中能加快啤酒成熟,有重要的应用价值。本研究将枯草芽孢杆菌启动子P43克隆到质粒pUC19-ALDC中的α-乙酰乳酸脱羧酶基因之前,得到重组质粒pUC19-P43-ALDC。重组质粒pUC19-P43-ALDC与质粒pMLK83-BN同源重组,筛选得到枯草芽孢杆菌整合质粒pMLK83-ALDC。用此整合质粒转化枯草芽孢杆菌1A751,挑选出新霉素抗性且无淀粉酶活性的重组菌株。此菌株用LB培养基在37℃、220r/min摇瓶培养过夜,测得α-乙酰乳酸脱羧酶活力为15.6U/mL,说明整合的α-乙酰乳酸脱羧酶基因能够在重组菌株中稳定传代和表达。本研究首次在枯草芽孢杆菌中用整合型的方式重组表达了α-乙酰乳酸脱羧酶,提出了一种有潜力的生产α-乙酰乳酸脱羧酶的新方法。     

正交试验法优化黄褐毛忍冬总皂苷的提取工艺

[目的]建立黄褐毛忍冬（Lonicera fulvotomentosa Hsu et S.C.Cheng）总皂苷的水提工艺。[方法]以黄褐毛忍冬总皂苷中有效成分α-常春藤皂苷的含量为考察指标,采用正交设计法考察加水量、煎煮时间、煎煮次数及浸泡时间4个因素对黄褐毛忍冬总皂苷提取工艺的影响,同时采用高效液相法测定α-常春藤皂苷的含量。[结果]加水量、煎煮次数、煎煮时间、浸泡时间对α-常春藤皂苷含量的影响程度不同,各因素影响程度的大小为：煎煮次数〉加水量〉浸泡时间〉煎煮时间,即煎煮次数对煎煮条件影响最大,为最重要的因素,其次为加水量、浸泡时间、煎煮时间。最优方案为：黄褐毛忍冬药材不用浸泡,加10倍量水煎煮3次,每次1.0h。方差分析结果表明,加水量和煎煮次数对α-常春藤皂苷含量的影响具有显著意义（PA=0.034〈0.05,PB=0.020〈0.05）,而煎煮时间、浸泡时间对水α-常春藤皂苷含量无显著影响（PC=0.500〉0.05,PD=0.264〉0.05）,对测定结果影响小,这与直观分析结果相吻合。[结论]优选提取工艺简单、稳定、可行。     

Functional analysis of the venom allergen-like protein gene from pine wood nematode Bursaphelenchus xylophilus using a baculovirus expression system

The pine wood nematode, Bursaphelenchus xylophilus, infects pine trees, leading to fatal pine wilt disease. Here, recombinant venom allergen-like protein (VAP) was obtained by expressing Bx-vap-1 in insect cells. Three-year-old Pinus massoniana were inoculated with recombinant VAP, simulating B. xylophilus esophageal gland secretions. Recombinant VAP up-regulated α-pinene synthase gene expression, the trees showed disease symptoms 15 d after inoculation and the xylem pith revealed brown tissue discoloration, indicating that recombinant VAP could damage P. massoniana cells. Recombinant VAP did not, however, lead to cavitation, indicating that the VAP secreted from B. xylophilus acts as a defense response elicitor.     

Improving the Field Emergence Performance of Super Sweet Corn by Sand Priming

Abstract

A priming method called sand priming was developed using sand as a priming solid matrix. The effect of sand priming on improving the field emergence performance of five super sweet corn cultivars was investigated. Sand priming significantly improved field emergence performance of all super sweet corn cultivars, and there was marked improvement by priming at 20ºC for 24 hr. After sand priming at 20ºC for 24 hr, field emergence percentage (FEP) of “Green Superman”, “Huatian 1”, “Yangtian 1”, “Mitian 8”, and “Chaotian 43” was increased by 52.1%, 37.5%, 38.0%, 40.9%, and 33.3%, respectively. Their field emergence speed (FES) was 2.3, 1.8, 2.0, 2.0, and 1.8 times of the control, respectively. To further elucidate the effect of sand priming on improving the field emergence performance of super sweet corn, we analyzed the membrane system integrity, α-amylase activity and protein content. Sand priming at 20ºC for 24 hr improved membrane system integrity and α-amylase activity in all super sweet corn cultivars. Furthermore, sand priming at 20ºC for 24 hr accelerated the degradation of embryo protein after 1 d germination in “Green Superman”.     

N-(α-萘乙酰基)-N-′(2-丙酸基)-硫脲的合成

研究了从α-萘乙酸出发,用一锅法合成出N-(α-萘乙酰基)-N-′(2-丙酸基)-硫脲。首先,α-萘乙酸与氯化亚砜反应生成α-萘乙酰氯,然后,再加入硫氰酸钾,并在乙腈为溶剂的条件下,合成α-萘乙酰基硫氰酸酯,最后,再与丙氨酸反应,生成目标产物。所得产物结构经IR初步确证。     

(甜)玉米澄清汁饮料加工工艺的研究

以甜玉米为原料,经提取玉米汁液,添加调配白砂糖和柠檬酸等,对甜玉米饮料的加工工艺(酶解,澄清)进行研究,研制出一种口味纯正的天然饮品。     

东北地区小麦赤霉病镰孢菌种群及其致病性测定

为了明确东北地区小麦赤霉病镰孢菌的种群组成及分布,分别从辽宁省沈阳市、黑龙江省哈尔滨市和密山市、内蒙古自治区扎兰屯市、呼伦贝尔市和通辽市等地区采集小麦赤霉病病样,经单孢分离纯化共得到118株镰孢菌,传统形态学鉴定的基础上,采用基因组DNA的EF-1α序列分析技术进行了镰孢菌种类的辅助鉴定,确定属于7个种:禾谷镰孢菌为优势种,分离频率为64.41%,藤仓镰孢菌为次优势种,分离频率为18.64%;燕麦镰孢菌、尖孢镰孢菌、木贼镰孢菌、锐顶镰孢菌和轮枝镰孢菌的分离频率分别为5.08%,3.39%,3.39%,3.39%,1.70%。同时,在玉米成株期进行了致病性测定,结果表明,小麦赤霉病镰孢菌可以侵染玉米,较玉米茎腐镰孢菌的致病力低。     

Cmponent Study on Flavonoids From Leaves of Dendrocalamus Latiflorus

从麻竹（Dendrocalamus latiflorus）叶中分离得到四个黄酮类化合物。经性质和光谱（UV,IR,MS,1HNMR,13CNMR等）法鉴定其结构,分别为牡荆苷（?）,芦丁（II）,山奈酚-3-O-β-D-芸香糖苷（III）,山奈酚-3-O-β-D-葡萄糖基(1-2)-α-L-鼠李糖苷（IV）。四种化合物均为首次从该植物中得到。     

Three new water-soluble alkaloids from the leaves of Suregada glomerulata (Blume) Baill

Three new water-soluble alkaloids (1-3) together with twelve known compounds (4-15) have been isolated from the water extract of leaves of Suregada glomerulata. Their structures were determined by spectroscopic analysis and chemical method. Compounds 1-3 were evaluated for their in vitro inhibitory activity against α-glucosidase and HIV-1 replication. However, no significant activities were found.