拟南芥AtEXPA1基因启动子的克隆及转录调控元件分析

扩张蛋白(expansin)是一类特异定位在细胞壁上具有酸生长活性的蛋白(Lee and Kende,2001;Chen and Bradford,2000),调控很多重要的生理过程(Cho and Cosgrove,2000),在时间和空间上的表达受到严格调控.本研究克隆了一个拟南芥expansin基因AtEXPAl的启动子,通过数种逆境胁迫诱导表达,对可能的活性响应部位进行了分析.     

拟南芥AtEXP1基因启动子的克隆及转录调控元件分析

为了研究拟南芥扩张蛋白AtEXPA1基因启动子上与转录调控有关的元件,我们通过PCR技术克隆了AtEXPA1基因上游897bp具有启动子活性的序列,再将启动子作不同程度截短,所有片段与GUS基因融合,构建植物表达载体,采用基因枪轰击拟南芥叶片和PEG介导转化烟草原生质体,通过定性和定量检测GUS的活性,发现在靠近翻译起始密码子的上游144bp之间存在增强转录活性的元件。将PEG介导转化的烟草原生质体,分别进行光诱导,冷诱导, 脱落酸（ABA）,盐处理,根据GUS定量检测的结果,推测（1）在AtEXPA1基因启动子上广泛存在与光调控有关的元件,（2） -897～-626 bp之间存在冷负调控元件, （3）-626～-444 bp之间存在与ABA负调控有关的元件,（4）-626～-282 bp之间存在与盐负调控有关的元件。     

基于BSA-seq的拟南芥辐射诱变突变体的基因定位

辐射诱变极易导致染色体结构变异,目前鲜有采用BSA-seq方法定位辐射诱变突变体基因的研究报道。为探索BSA-seq用于辐射诱变突变体的基因定位的可行性,本研究通过辐射诱变筛选得到一个拟南芥突变体,将其与亲本杂交,在F2代分离群体中根据表型筛选单株,构建两个极端表型的子代混池;将两个子代混池与亲本混池进行全基因组测序,使用MutMap、QTL-seq和GPS等多种BSA-seq定位策略对其进行定位分析。结果表明,多种BSA-seq定位策略均取得了一致的结果,在2号染色体上获得7 Mb的初步定位区间;使用IGV软件对该区间内的基因组进行可视化,发现该区间内存在25 189 bp的大片段缺失,缺失区段包含6个基因;通过SnpEff进行突变位点注释,经基因注释信息推测AT2G28610为候选基因;通过遗传学试验验证了该候选基因为突变基因。本研究结果为应用BSA-seq技术定位辐射诱变得到的突变位点提供了参考。     

小鼠基因内含子中CpG岛和几个转录调控元件分析

内含子在基因转录调控中的作用已多次被实验报道,然而对其参与调控的普遍性还缺乏足够的理论支持。本研究利用计算分析方法,对小鼠基因内含子中的CpG岛（CpGisland）、TATA框（TATAbox）、CAAT框（CAATbox）以及GC框（GCbox）等元件的出现频率进行分析。结果发现,分别有56.01%、57.16%、65.88%和41.86%的第一内含子具有CpG岛、TATA框、CAAT框以及GC框,而它们在其它内含子中的平均出现频率则分别为14.07%、45.24%、49.91%和13.19%。即使考虑到不同位置的内含子,这些元件在第一内含子中的出现频率也显著高于它们在其它任何位置内含子中的出现频率。由于CpG岛、TATA框、CAAT框以及GC框均与基因的转录调控有关,据此推测小鼠第一内含子在基因转录调控过程中具有潜在的重要性。本研究结果为内含子参与转录调控提供了更多的理论依据。     

蓝藻生物节律性分子调控机制的研究进展

生物钟现象是一种普遍存在于生物界细胞的内源节律性保持机制。生物钟机制的存在可以使生物体的代谢行为产生并维持以24h为周期的昼夜节律,从而更好地适应于地球自转所产生的环境条件昼夜间节律性变化。蓝藻是目前生物钟分子机制研究中的模式生物,其依赖于kai基因家族成员的核心生物钟调控模式已经被众多研究者详细阐明。蓝藻生物钟的核心振荡器是由蓝藻kaiA／B／C的编码产物来调控的,Kai蛋白的表达模式具有节律性。KaiC蛋白磷酸化状态的节律性循环及输入、输出途径相关组成蛋白的翻译后修饰状态节律性循环共同组成其反馈回路,负责维持生物钟节律性振荡的持续进行并与环境周期保持同步。传统的蓝藻生物钟分子机制模型认为,节律性表达基因翻译产物的转录／翻译负反馈抑制环是生物节律性维持和输出的关键。遗憾的是,在其它物种生物钟分子机制研究中未发现由ka／基因家族成员同源基因组成的节律性标签,这表明以kaiA／B／C为核心振荡器的生物钟系统并不是一种跨物种保守的生物钟系统。近期,人们发现非转录／翻译依赖的振荡器（NTO）也具有成为生物节律性产生和维持的“源动力”的可能。过氧化物氧化还原酶（Pax）氧化还原状态节律性是第一种被报道的跨物种保守的NTO节律性标签,这也日渐成为蓝藻生物钟分子机制研究新的热点。     

生物钟控制皮肤癌的发生

在美国,皮肤癌是最普通的一种癌症,每年有超过130万的新增病例,占所有类型癌症的40%。由于生活方式和环境的变化,皮肤癌发生的几率正稳定增长。引发皮肤癌的主要原因是太阳光中的UV成分。UV辐射(UVR)主要在DNA上产生两种损     

农村配电网网架结构规划方法研究

针对我国农村电网的现状,阐述了农网网架规划的主要内容及规划方法,分析了几种网架规划中采用的智能优化算法,指出智能技术的应用是电网规划的发展方向。     

黄土丘陵区县南沟流域农业产业-资源系统链网结构分析

针对黄土丘陵区农业产业—资源系统链网结构发生重要变化的现实,对县南沟流域退耕以来农业产业—资源系统链网结构变化过程以及演变路径进行了分析。结果表明:农业产业—资源系统链网结构变化过程可以划分为四个阶段:（I）生态系统修复阶段→（Ⅱ）经济系统（结构）适应阶段→（Ⅲ）农业产业—资源系统相悖阶段→（Ⅳ）农业产业—资源系统优化耦合阶段,系统已经经历了I、Ⅱ、Ⅲ阶段,现处于第Ⅲ阶段。在这个过程中农业资源系统得以恢复重建,农业产业系统结构逐渐调整,经济效益逐年上升,然而产业系统与资源系统并未达到协调发展状态,目前林草资源丰富且未得到合理、有效利用,因此需要进一步优化农业产业—资源耦合系统结构,以促进区域可持续发展。同时,还可以得出:农业产业—资源系统链网结构可通过资源环境、农业资源、农业产业、经济效益予以表征。     

The Current Core Literature of the Agricultural Sciences

ABSTRACT

A five year project to identify the most vital or core literature of the agricultural sciences was undertaken with results for the advanced countries as well as the Third World countries. Citation analysis and other bibliometric techniques were used to identify the most valuable literature for university-level instruction and research. Monographs in seven sub-disciplines of agriculture were evaluated by researchers resulting in a composite list of 8,400 volumes and in 363 core journals. Methods of analysis, evaluation techniques, and end products are described. Four of seven books describing the literature of agriculture have been published. A final product will be the transfer of the full text of the monographs and the journals for a five year period onto compact disk for use in the Third World. Because of copyright and other restrictions, the estimated 280 disk library will not be available to developed countries.     

南昌市生态用地景观结构与网络连通性多情景模拟

[目的]探究未来不同发展情境下,江西省南昌市生态用地景观结构与网络连通性变化差异,以期为该市环境保护规划与工程建设提供科学参考。[方法]基于PLUS模型对未来南昌市生态用地格局进行多情景预测,并通过景观格局指数、形态学空间格局分析(MSPA)与网络连接度分析,从数量与结构两个角度,研究不同开发强度下,城市不同区域与结构的生态用地景观结构与网络连通的差异。[结果](1)不同发展情境下,生态用地破坏均主要集中于安义县、新建区境内;(2)草地破碎化极为严重,在任意发展情景下景观结构差异不大,而林地与水域在情景ED(经济优先)与EP(环境保护)下,景观指数差异较小,对中高强度的开发表现出较强的抗性;(3)不同发展情景下,生态核心区面积之间的差异高达90.36 km²,且多类型均匀混合结构的生态用地可以有效抑制孤岛的产生,维护区域生态安全;(4)相较于2020年,在各情景下,南昌市等效可能连通性指数EC(PC)下降了18.76%～23.24%,新建区、安义县境内网络连通性下降较为明显。[结论]生态保护情景(EP)发展方案可以有效地保护南昌市生态景观结构与网络安全,保障城市的...     

全国水土保持监测网络的总体结构及管理制度

全国水土保持监测网络是一个由各级监测机构和监测站点构成的层次式网络结构。它既是一个组织和管理监测的工作体系网络 ,又是一个数据传递、整 (汇 )编、交流和发散的数据交换网络。提出了监测网络行政管理体制和业务运行机制     

A Review of the Technologies for Mapping Within-field Variability

Techniques for mapping soil physical and chemical condition, topography and the weed status of fields, are reviewed from a practical and economic perspective. The conclusions are that it is possible to target sample the soil physical and chemical status of fields and locate areas of high weed density following the use of inexpensive, non-invasive techniques electromagnetic induction (EMI) aerial digital photography (ADP) and radiometry. Semi-automated field reconnaissance systems on all terrain vehicles and combines also assist in locating the position of weed patches. P and K fertiliser can be replenished by using the ‘off-take’ values determined from yield maps, whilst crop density in the spring period shows potential for the management of nitrogen fertiliser in cereal crops using ADP and could also be a benefit in the application of agrochemicals. Currently, the most economically viable method to determine field topography is to use very simple surveying techniques, and there is potential to automate this.     

Mapping the Literature of Food Science Using Co-Citation Analysis

ABSTRACT

This study mapped the scholarly literature in the discipline of food science using co-citation analysis and explored the relationships found within this literature. Using the Journal of Food Science, an examination of a random sample of its articles published from 2000 to 2002 yielded a ranked list of frequently-cited journals. The top thirteen most frequently-cited journals formed a core set for further analysis. Using the SciSearch online database and a standard statistical package (SPSS), a two-dimensional map was created, relationships between the journals were studied, and the discipline of food science was explored. Food science journals tended to be either industry-specific (e.g., dairy science) or industry-general. The journals also tended to focus on either “pure” science (e.g., chemistry) or on applied science and technology. Of the thirteen journals mapped, six fell within the area of pure science, while four were in the area of applied science. Interestingly, three journals fell on the axis line dividing the two. At the same time, seven journals had the characteristics of being industry-general, while six were more industry-specific. The results are consistent with previous indications of the interdisciplinary nature of the field of food science, drawing as it does from many fields such as chemistry, microbiology, engineering, and agricultural science.     

Identifying the Core Periodical Literature of the Agricultural Communications Documentation Center

ABSTRACT

“Agricultural communications” is an emerging field which is naturally both part of the “agriculture” and “communications” literature. However, it is much broader than just a subset of each. The coverage of standard databases such as CAB Abstracts and Communication Abstracts, while a good start, does not sufficiently cover the field. The Agricultural Communications Documentation Center (ACDC) at the University of Illinois at Urbana-Champaign has, over the last quarter century, worked to help define and collect this literature, by identifying relevant documents and entering them into a Web-searchable Microsoft Access database. An analysis of this database reveals important clues concerning the literature of agricultural communications. Of the nearly 30,000 documents within the ACDC collection, periodical articles comprise a little over one half, from a core list of 45 periodicals within the ACDC collection. More than one half of these core periodicals are outside the traditional agriculture and life science literature; approximately one third are scholarly journals.