In vitro Selection of DNAAptamers and Fluorescence-Based Recognition for Rapid Detection Listeria monocytogenes

Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment （SELEX） was used to select and PCR amplify DNA sequences （aptamers） capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential （log） phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monoeytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets.     

ISSR-Based Molecular Characterization of an Elite Germplasm Collection of Sweet Potato （Ipomoea batatas L.） in China

To determine the genetic diversity and population structure of sweet potato accessions cultivated in China, and to establish the genetic relationships among their germplasm types, a representative collection of 240 accessions was analyzed using inter-simple sequence repeat （ISSR） markers. The mean genetic similarity coefifcient, Nei’s gene diversity, and shared allele distance of tested sweet potato accessions were 0.7302, 0.3167 and 0.2698, respectively. The 240 accessions could be divided into six subgroups and ifve subpopulations based on neighbor-joining （NJ） clustering and STRUCTURE results, and obvious genetic relationships among the tested sweet potato accessions were identiifed. The marker-based NJ clustering and population structure showed no distinct assignment pattern corresponding to lfesh color or geographical ecotype of the tested sweet potato germplasm. Analysis of molecular variance （AMOVA） revealed small but signiifcant difference between white and orange-lfeshed sweet potato accessions. Small but signiifcant difference were also observed among sweet potato accessions from the Southern summer-autumn sweet potato region, the Yellow River Basin spring and summer sweet potato region and the Yangtze River Basin summer sweet potato region. This study demonstrates that genetic diversity in the tested sweet potato germplasm collection in China is lower than that in some reported sweet potato germplasm collections from other regions. Pedigree investigations suggest that more diverse Chinese sweet potato varieties should be formed by broadening the selection scope of breeding parents and incorporating the introduced varieties into future breeding programs.     

基于支持向量回归与地统计学的农民收入预测

农民收入既受其自身动态时序特性的影响,又与国家政策、农产品产量、天气等多种人为因素和自然因素关系密切,是一种典型的多维时间序列数据.该研究以国民总收入、乡村人口等11个可能与农民收入相关的影响因子为自变量,农村居民家庭平均每人纯收入为因变量,基于1982～2011年我国相关统计数据,采用支持向量回归与地统计学非线性时间序列预测模型对农民收入进行分析.结果表明：非线性时间序列预测模型大幅度提高了农民收入预测精度;农民的主要收入来源已不是粮食生产,而是向其他农业生产、进城务工等方面转移.     

基于两类全基因组距离的EV71型病毒亲缘关系分析

[目的]了解世界各地EV71病毒的亲缘关系。[方法]下载了NCBI数据库所有EV71全基因组序列,以常用的Kimura 2-parameter距离和E距离进行距离矩阵邻接法建树。[结果]基于E距离和Kimura 2-parameter距离构建的进化树结果一致,2种方法均支持EV71进化树反映出的基于全基因组的病毒亲缘关系。[结论]E距离是病毒系统发育应用中另一种颇具潜力的新距离,能为鉴定EV71病毒亲缘关系提供支持。     

基于ARMA模型的运城市果蔬肉类价格预测研究

[目的]预测果蔬肉类价格。[方法]采用自回归滑动平均模型(ARMA模型)对价格进行预测。[结果]近6周的预测结果可信度高,具有较低的相对误差率。[结论]运用ARMA模型可对果蔬肉类价格进行预测且预测效果良好。     

中卫市中央大道景观带文化序列景观设计探析

以中卫市中央大道景观带设计为例,立足沙漠边缘的实际,紧扣"沙文化"主题,探索滨河城市干道的地域文化与绿色生态景观相融合的有效途径,以充分认识文化意蕴对城市干道景观建设的理论研究和实践的重要意义。     

牛源犬新孢子虫IMP1基因的克隆与序列分析

[目的]为了解牛源犬新孢子虫IMP1基因生物学特性,分析牛源犬新孢子虫IMP1基因的克隆与序列。[方法]应用PCR技术扩增IMP1基因,将纯化的PCR产物和pMD18-T Simple Vector连接,构建pMD18-IMP1重组克隆质粒,进行PCR鉴定和酶切鉴定,将鉴定为阳性的质粒进行测序分析。[结果]PCR扩增犬新孢子虫IMP1基因大小为762 bp,克隆质粒经测序分析与GenBank（XM003879531.1）中IMP1基因的同源性为99.9%。[结论]该试验为犬新孢子虫IMP1基因的表达及后续研究奠定了基础。     

中国农科院专家揭示野生大豆遗传变异特征

中国农业科学院作物科学研究所邱丽娟研究团队在国际上率先构建出一年生野生大豆的泛基因组,在全基因组水平上阐明了大豆种内、种间结构变异的特点。发掘出野生大豆特有的优异基因,发现野生大豆中生物逆境抗性相关的抗病基因类型远多于栽培大豆,同时栽培大豆驯化过程中一系列重要性状如开花、脂肪合成及产量等相关基因候选基因也发生了变化,为阐明人工选择过程中大豆育成品种的基因变异提供了重要的线索,为作物野生种质资源保护、基因发掘和育种利用研究提出了新的方法。     

内蒙古4种白粉菌的ITS序列分析

采用chelex-100法提取内蒙古地区4种白粉菌的基因组DNA,扩增其r DNA内转录间隔区序列ITS,连接载体测序,并基于ITS序列进行亲缘关系分析。结果表明,4种白粉菌形成3个进化距离较远的分支;寄生在豌豆和田旋花上的豌豆白粉菌和旋花白粉菌的ITS序列紧密聚在1支,其亲缘关系较近,同属白粉菌属;寄生在紫花苜蓿上的托罗斯内丝白粉菌和寄生在山桃上的三指单囊白粉菌各自成1支,与形态学分类结果相一致。ITS序列可用于内蒙古地区白粉菌分类鉴定研究。     

孔雀与鹌鹑MC1R基因片段的鉴定及序列分析

探讨了孔雀、鹌鹑黑素皮质素受体1(melanocortin 1-receptor,MC1R)基因序列与禽类羽色的相关性。根据GenBank上原鸡的MC1R基因序列,利用在线引物设计软件Primer3在编码区设计引物PE。以孔雀和鹌鹑DNA为模板进行PCR扩增及测序,分别获得长度约为350 bp的基因片段。经比对发现,孔雀与原鸡的相似性为95.47%,有16处突变,3处缺失;鹌鹑与原鸡的相似性为97.70%,有8处突变,1处缺失。对其氨基酸序列进行蛋白质二级结构预测,结果显示,孔雀与鹌鹑α螺旋、β折叠、无规则卷曲所占比例分别为59.48%,2.59%,37.93%和58.62%,1.82%,39.66%。表明MC1R基因可能是表达禽类羽色的主效基因。