香菇顺式调控元件的克隆及其序列分析*

应用顺式调控元件探测载体G221构建了一个香菇Lentinula edodes基因组文库。G221为大肠杆菌-酿酒酵母穿梭载体,含有一个由酵母Cyc1基因基本启动子控制的lacZ标记基因,能以转录增强活性筛选香菇DNA片段。用这个基因组文库转化酵母菌,获得了一批lacZ阳性转化子。对其中表达较强的阳性转化子进行质粒抽提和双酶切鉴定,筛选到50个香菇顺式调控元件DNA片段。对其中部分片段进行了测序,并对其中一个序列进行了序列分析,鉴别了该序列上的几个与转录相关的特征序列。该研究也探讨了利用酵母表达系统克隆香菇顺式调控元件的可行性。     

凋亡蛋白和Nmi的相互作用及作用位点的筛选鉴定

为研究来源于鸡贫血病毒的小分子蛋白质———凋亡蛋白 (apoptin)诱导肿瘤细胞凋亡的分子机制 ,利用酵母双杂交系统从人白细胞cDNA文库筛选凋亡蛋白相互作用蛋白质 ,核苷酸序列分析及同源性检索表明 ,其中一个约为 1.2kb的克隆与Nmi(N Mycinteractionprotein)高度同源。细胞免疫共沉淀实验结果显示 ,在哺乳动物细胞水平仍能够检测到凋亡蛋白与全长Nmi的特异相互作用。利用构建好的分别缺失C端 11个氨基酸、中间 33～46位氨基酸和二者均缺失的 3个凋亡蛋白突变体进行相互作用位点研究 ,结果表明凋亡蛋白的 33～ 46位氨基酸(核外运信号 )对于凋亡蛋白与Nmi的相互作用是必需的 ,而C端核定位信号 /DNA结合序列对于凋亡蛋白与Nmi的相互作用不是充分必要的     

Isolation of transcription factors binding auxin response elements using a yeast one-hybrid system

Plant hormones play an important role during higher plant embryogenesis. Auxin is central to the development of vascular tissues, formation of lateral and adventitious roots, control of apical dominance, and tropic responses. Auxin response element (AuxRE), present in the promoters of many auxin-induced genes, can confer auxin responsiveness. Using carrot somatic embryo under specific developmental phase, a cDNA expression library was constructed. Several plasmids were recombined containing the tetramer of AuxRE as a bait. After screening by a yeast one-hybrid system, one positive clone was confirmed and characterized. Electrophoretic mobility shift assay showed that AxRF1 protein expressed in yeast cell could bind AuxRE in vitro. It suggests that AxRF1 participates in regulation of the expression of auxin responsive gene during carrot somatic embryogenesis.     

Potato cyst nematodes in England and Wales - occurrence and distribution

Potato cyst nematodes (PCN) have been known to occur in the UK for nearly a hundred years. They are the most problematic pests of potatoes and can cause severe yield losses. Previous work has shown the two species, Globodera rostochiensis and G pallida, to be distributed throughout the UK. This paper reports the results of the first structured and statistically unbiased survey undertaken to assess their occurrence and distribution in the potato growing land of England and Wales. The survey showed that PCN were present in 64% of sites sampled. Of the populations found, 67% were G pallida, 8% were G rostochiensis and 25% contained both species. The results show an increase in the incidence of PCN since previous studies were completed and confirm the perceived shift towards G pallida as the predominant species. Of the infestations found, 62% had a population density of less than 10 eggs g^?1 soil.     

Discriminating Tsuga canadensis Hemlock Forest Defoliation Using Remotely Sensed Change Detection

The eastern hemlock (Tsuga Canadensis) is declining in health and vigor in eastern North America due to infestation by an introduced insect, the hemlock woolly adelgid (Adelges isugue). Adelgid feeding activity results in the defoliation of hemlock forest canopy over several years. We investigated the application of Landsat satellite imagery and change-detection techniques to monitor the health of hemlock forest stands in northern New Jersey. We described methods used to correct effects due to atmospheric conditions and monitor the health status of hemlock stands over time. As hemlocks defoliate, changes occur in the spectral reflectance of the canopy in near infrared and red wavelengths—changes captured in the Normalized Difference Vegetation Index. By relating the differences in this index over time to hemlock defoliation on the ground, four classes of hemlock forest health were predicted across spatially heterogeneous landscapes with 82% accuracy. Using a time series of images, we are investigating temporal and spatial patterns in hemlock defoliation across the study area over the past decade. Based on the success of this methodology, we are no expanding out study to monitor hemlock health across the entire Mid-Atlantic region.     

Use of Remote Sensing to Detect Soybean Cyst Nematode-Induced Plant Stress

Integrating remote sensing and geographic information systems (GIS) technologies offers tremendous opportunities for farmers to more cost effectively manage the causes of crop stress. Initial soybean cyst nematode (SCN) population densities from 995 2-×-3-m quadrats were obtained from a soybean field near Ames, Iowa, in 2000. The percentage of sunlight reflected from each quadrat was measured weekly using a multispectral radiometer beginning in mid-May and continuing through mid-September. Aerial images were obtained at heights above the field ranging from 45 to 425 m on 12 dates during the soybean growing season. This was accomplished using color film and infrared film in conjunction with a filter to measure reflectance in the near-infrared region (810 nm). Satellite images (Landsat 7) were obtained for five dates during the 2000 growing season. Maps depicting initial SCN population densities, soybean yield, soy oil, and soy protein were generated using the GIS software program ArcView. Percentage reflectance (810 nm), aerial image intensity, and satellite image intensity data then were regressed against soybean yield, soy oil, and soy protein concentrations obtained from each geospatially referenced soybean quadrat. Percentage reflectance measurements explained up to 60% of the variation in initial SCN population densities within soybean quadrats and up to 91% of the variation in soybean yield. Aerial image and satellite image intensities explained up to 80% and 47% of the variation in soybean yield, respectively. Percentage reflectance data also explained 36% and 54% of the variation in oil and protein concentrations of the harvested soybeans, respectively. These results indicate that remote sensing coupled with GIS technologies may provide new tools to detect and quantify SCN population densities and their impacts on the quantity and quality of soybean yield.     

芽殖酵母细胞周期的检查点调控

芽殖酵母是研究真核细胞的模式菌。细胞周期检查点是确保细胞周期正常运行的一种调控机制。就芽殖酵母细胞周期检查点调控加以介绍。     

基于超声心动图的二尖瓣轮廓提取

针对超声心动图噪音大,灰阶少等弱点,采用多阈值的门限法对图象进行正确分割,在通过跟踪特征点进行匹配的基础上,采用匹配后插值的方法,提高了匹配的精度。并利用前一帧的速度解决了粘连在一起的二尖瓣轮廓线的分割问题。实验取得了较满意的结果。     

面包酵母海藻糖积累条件的研究

对面包酵母的海藻糖积累条件及补料分批发酵进行了研究。结果表明 pH为 5 .0 ,温度 37℃有利于海藻糖积累。少量多次的补加葡萄糖可持续增加海藻糖的含量 ,但随着发酵时间的延长 ,葡萄糖对海藻糖转化率有逐渐减少的趋势。     

HBsAg生化性状对乙型肝炎疫苗效力影响的研究

比较研究了重组酵母HBsAg P24亚基间二硫键结合及其还原条件下降解程度对乙型肝炎疫苗效力的影响。分别用HPLC及SDS－PAGE法检测重组酵母乙型肝炎疫苗HBsAg的P24亚基在还原条件下降解和P24亚基间二硫键桥联程度,并检测乙型肝炎疫苗小鼠体内效力（ED50值）和体外相对效力（RP）,分析HBsAg的P24亚基间二硫键结合及其还原条件下降解程度对乙型肝炎疫苗效力的影响。结果表明HBsAgP24亚基还原条件下降解成分Sub-P24的相对含量在5．2％－31％间,P24亚基间二硫键桥联型HBsAg颗粒相对含量在41．9％－71．8％范围内与疫苗的实验室效力无关。所生产重组酵母乙型肝炎疫苗HBsAg的P24亚基间二硫键结合及其还原条件下降解程度不影响乙型肝炎疫苗实验室效力。