油菜基因流网络的结构特性与小团体分析

为从系统角度掌握转基因油菜（Brassica campestris）基因流规律,基于常规油菜与十字花科植物杂交的有关文献,构建了油菜基因流网络拓扑图实例并分析其网络结构特性。研究结果表明,该网络节点度服从幂律分布,具有无标度特性。从随机攻击和恶性攻击两个方面对标准结构熵和网络效率2个指标的网络稳健性进行分析,结果显示在随机移除不到10%的顶点时网络表现较好的鲁棒性,但在受到选择性移除10%的顶点时,网络具有极弱的抗攻击性。基于软件UCINET对网络进行了小团体和结构同型性分析,可将网络中298个节点22类十字花科植物划分为2个小团体和5类结构角色,其中甘蓝型油菜在基因流网络小团体中具有关键性作用。这些研究结果可为揭示转基因油菜基因流规律提供新思路,同时也可对转基因油菜商业化种植采取合理的农业生产栽培管理措施提供参考。     

转基因甘蓝型油菜亲和性等级识别方法构建

为预测转基因甘蓝型油菜商业释放的基因流环境生态风险,基于模糊数学中模糊聚类分析与模糊模型识别,并结合生物统计学相关知识,构建了转基因甘蓝型油菜亲和性等级识别方法.该方法包含转基因甘蓝型油菜种间组合亲和性的模糊聚类分析、模糊聚类结果F检验、种间组合风险等级划分和风险等级模式识别4个基本步骤.并在等级模式识别步骤中针对样本数据收集情况的不同,构建了不同的等级识别方法,与传统聚类的硬性划分相比更具灵活性.以收集的常规油菜杂交实验数据聚类形成6个风险等级模式,将一甘蓝型油菜种间杂交实验进行亲和性等级识别为例对该方法进行了演示,论证了该方法具可操作性.     

油菜BnCr4基因RNAi载体构建及植株转化

该实验构建了含甘蓝型油菜黄化相关基因BnCr4特异片段反向重复结构的RNA干扰(RNAi)载体pFGC5941-Cr4,通过根癌农杆菌介导转化油菜,获得47株抗Basta的抗性再生油菜植株,其中10株经PCR鉴定为阳性转基因植株.随机选取3株经鉴定的转基因阳性油菜植株进行半定量RT-PCR分析,结果显示,相对于非转基因的野生型油菜,3株转基因植株中BnCr4基因的表达量分别降低了78.5%、8.5%、11.8%,表明该干扰载体转入油菜能特异引起植株BnCr4基因表达量下降.     

西南地区麻疯树天然种群遗传多样性的等位酶变异

为了揭示麻疯树(Jatropha curcas)天然种群的遗传多样性和遗传结构, 采用聚苯烯酰胺凝胶垂直平板电泳技术, 对采自四川、云南、贵州3个省的10个麻疯树天然种群的叶片样本进行了同工酶分析。7个酶系统10个位点的检测结果表明: 麻疯树种群水平上的遗传多样性较高, 每位点平均等位基因数为2.428 6, 多态位点百分率为97.14%, 平均期望杂合度为0.396 4。种群间遗传分化系数为0.041 3, 种群间总的基因流较高, 为5.808 9, 种群间遗传一致度较高(Shannon信息指数为0.921 7- 0.995 3)。非加权类平均法(UPGMA)聚类结果显示, 10个种群的遗传距离与地理距离相关性不显著。麻疯树天然种群具有较低程度的遗传分化、较高的基因流, 种内及种群内多样性丰富, 这为麻疯树优良品种的选育提供了良好的遗传基础。     

早熟油菜成花相关基因LFY的克隆与分析

以甘蓝型油菜晚熟品种RG-8的早熟突变体RG-8M为材料,通过同源克隆法得到1个LEAFY(LFY)同源基因,命名为BnLFY。该基因cDNA全长为1 310bp,包含1个长为1 248bp的开放阅读框,编码415个氨基酸。序列分析表明,推测的氨基酸序列含双子叶植物LFY类蛋白特有的N端脯氨酸富集区、中央酸性区、亮氨酸拉链结构以及富含赖氨酸与精氨酸的碱性区;且与几种十字花科植物LFY类蛋白的氨基酸序列一致性均在84%以上。转录表达分析表明,BnLFY基因在油菜中为组成型表达。     

5种转基因油菜转化体特异性多重PCR检测方法

【目的】全球转基因植物及其产品的数量和种类越来越多,迫切需要可同时精准高效检测多个转化载体的检测方法。【方法】针对RF1、MS8、Topas19/2、Oxy235和RF3等5个转基因油菜品系的侧翼序列及油菜内源基因cruciferin A(Cru A)序列设计多重聚合酶链式反应特异性引物,通过对转基因油菜、转基因大豆、转基因玉米、转基因水稻、转基因棉花等不同作物进行PCR扩增来测试所选择的引物特异性,优化多重PCR反应引物的浓度,用所建立的检测体系对不同混合比例的转基因油菜进行多重PCR扩增来测试所建立的检测方法的灵敏度。【结果】通过测试,仅在含有目标样品中检测出阳性结果,灵敏度达0.05%,表明所建立的6重PCR检测方法可同时精准检测RF1、MS8、Topas19/2、Oxy235和RF3等5种转基因油菜转化载体。【结论】所建立的6重转基因油菜转化体特异性PCR检测方法通量高、特异性好、灵敏度高,符合有关转基因产品检测的要求,可作为转基因油菜检测的有效方法。     

基于网络分析的城市生态空间结构优化——以常州市为例

经济社会的高速发展带来城市的快速扩张,造成城市生态空间的萎缩和生态功能的下降,城市生态安全受到严重威胁。系统研究城市生态空间结构,提出针对性保护和优化措施,对于城市的可持续发展具有重大意义。本研究以常州市为研究区,考虑城市生态空间的自然生态功能和社会服务功能两方面,构建基于自然生态的“源地-廊道”与基于人文生态的“供给-需求”两类生态网络,对于源地廊道生态网络,主要从节点重要性、网络连通性与稳定性进行定量分析,对于供给需求生态网络,主要从节点重要性、供需均衡与稳定性进行定量分析。结果表明: 常州市主城区源地廊道生态网络的连通性与稳定性水平不高,供给需求生态网络的稳定性水平一般且存在服务供给与需求的空间错位。从连通性与稳定性提升角度,提出新增12个源地节点与57条廊道的源地廊道生态网络优化方案;从供需均衡与稳定性提升角度,提出新增22个供给节点的供给需求生态网络优化方案。对比初始源地廊道生态网络,优化网络连通性水平提升10%,稳定性提升0.05;对比初始供给需求生态网络,优化网络的服务水平提升4%,网络稳定性提升0.10。最后,综合两类生态网络,分别针对现状保护斑块与新增节点两类对象,提出了保护与管理实施方案。     

玉米转基因技术专利权人合作态势分析

转基因玉米是最重要的转基因主粮作物之一,其转基因技术具有一定的代表性。为了更好地了解和掌握玉米转基因技术领域研发主体合作情况,文章构建了基于专利权人合作网络的目标技术领域专利权人合作态势分析框架,并基于社会网络分析方法与技术,以世界范围内的转基因玉米领域的重要专利权人为分析对象,构建合作网络、分析整体合作特征、挖掘合作子网、探测领域内重要专利权人,从而从宏观、中观和微观三个层面客观展现玉米转基因技术领域专利权人合作态势,为科技战略规划提供一定的决策支撑。     

适于转基因油菜RT73品系特异性检测的标准分子构建及其适用性鉴定

针对目前转基因产品检测标准物质缺乏的难题,构建适于转基因油菜RT73品系特异性检测的标准分子pEASY-RT73.其包含转基因油菜RT73品系3'端侧翼序列,油菜内标准基因HMG和PEP片段.对其在定性和定量检测中的适用性进行了实验室内部验证,结果表明,标准分子pEASY-RT173高度特异于转基因油菜RT73品系.以标准分子为标准品的普通PCR扩增中,3个目标片段的检测下限(LOD)均为10拷贝.实时荧光PCR检测的LOD均为25拷贝,定量下限(LOQ)均为50拷贝.以标准分子为标准品构建的标准曲线反应效率介于0.96-1.02间,相关系数均大于0.999.分别以PEP和HMG为内标准基因对5个盲样的测试结果显示,测量值与设定值间偏差(Bias)介于-14.13%-14.29%间,SD小于0.20,RSD小于18.0%.因此,标准分子pEASY-RT73可很好地替代植物来源阳性标准品用于转基因油菜Rt73及其来源产品品系特异性检测.     

重花瓣油菜的发现及其生产意义

在十字花科植物中,除了紫罗兰属（Matthiola）具有不育的重花瓣现象以外,其它各属植物均为十字对称四花瓣的能育单瓣花。十字花科植物花器官的这一重要特征,是该物种长期以来进化过程中所形成和固定下来的,具有稳定的遗传特性。以往,人们在自然界的突变体中,虽也发现了能稳定遗传的油菜（Brassi－cacampestris）无花瓣的类型,但据研究,此属于花瓣的退化现象。为什么在花器官中花瓣的数目有多有少？根据花是变态短枝的观点,花的各部分均具有一般叶片的性质,其中雄蕊和雌蕊都可发生变态形成花瓣。因此,从理论上讲,油菜的花部除具…     

Distributed Clone Detection in Static Wireless Sensor Networks: Random Walk with Network Division

Wireless Sensor Networks (WSNs) are vulnerable to clone attacks or node replication attacks as they are deployed in hostile and unattended environments where they are deprived of physical protection, lacking physical tamper-resistance of sensor nodes. As a result, an adversary can easily capture and compromise sensor nodes and after replicating them, he inserts arbitrary number of clones/replicas into the network. If these clones are not efficiently detected, an adversary can be further capable to mount a wide variety of internal attacks which can emasculate the various protocols and sensor applications. Several solutions have been proposed in the literature to address the crucial problem of clone detection, which are not satisfactory as they suffer from some serious drawbacks. In this paper we propose a novel distributed solution called Random Walk with Network Division (RWND) for the detection of node replication attack in static WSNs which is based on claimer-reporter-witness framework and combines a simple random walk with network division. RWND detects clone(s) by following a claimer-reporter-witness framework and a random walk is employed within each area for the selection of witness nodes. Splitting the network into levels and areas makes clone detection more efficient and the high security of witness nodes is ensured with moderate communication and memory overheads. Our simulation results show that RWND outperforms the existing witness node based strategies with moderate communication and memory overheads.     

Rich-Cores in Networks

A core comprises of a group of central and densely connected nodes which governs the overall behaviour of a network. It is recognised as one of the key meso-scale structures in complex networks. Profiling this meso-scale structure currently relies on a limited number of methods which are often complex and parameter dependent or require a null model. As a result, scalability issues are likely to arise when dealing with very large networks together with the need for subjective adjustment of parameters. The notion of a rich-club describes nodes which are essentially the hub of a network, as they play a dominating role in structural and functional properties. The definition of a rich-club naturally emphasises high degree nodes and divides a network into two subgroups. Here, we develop a method to characterise a rich-core in networks by theoretically coupling the underlying principle of a rich-club with the escape time of a random walker. The method is fast, scalable to large networks and completely parameter free. In particular, we show that the evolution of the core in World Trade and C. elegans networks correspond to responses to historical events and key stages in their physical development, respectively.     

Lysophosphatidic acid acyltransferase from meadowfoam mediates insertion of erucic acid at the sn-2 position of triacylglycerol in transgenic rapeseed oil.

Lysophosphatidic acid acyltransferase acylates the sn-2 hydroxyl group of lysophosphatidic acid to form phosphatidic acid, a precursor to triacylglycerol. A cDNA encoding lysophosphatidic acid acyltransferase was isolated from developing seeds of meadowfoam (Limnanthes alba alba). The cDNA encodes a 281-amino acid protein with a molecular mass of 32 kD. The cDNA was expressed in developing seeds of transgenic high-erucic-acid rapeseed (Brassica napus) using a napin expression cassette. Erucic acid was present at the sn-2 position of triacylglycerols from transgenic plants but was absent from that position of seed oil extracted from control plants. Trierucin was present in the transgenic oil. Alteration of the sn-2 erucic acid composition did not affect the total erucic acid content. These experiments demonstrate the feasibility of using acyltransferases to alter the stereochemical composition of transgenic seed oils and also represent a necessary step toward increasing the erucic acid content of rapeseed oil.     

Node Survival in Networks under Correlated Attacks

We study the interplay between correlations, dynamics, and networks for repeated attacks on a socio-economic network. As a model system we consider an insurance scheme against disasters that randomly hit nodes, where a node in need receives support from its network neighbors. The model is motivated by gift giving among the Maasai called Osotua. Survival of nodes under different disaster scenarios (uncorrelated, spatially, temporally and spatio-temporally correlated) and for different network architectures are studied with agent-based numerical simulations. We find that the survival rate of a node depends dramatically on the type of correlation of the disasters: Spatially and spatio-temporally correlated disasters increase the survival rate; purely temporally correlated disasters decrease it. The type of correlation also leads to strong inequality among the surviving nodes. We introduce the concept of disaster masking to explain some of the results of our simulations. We also analyze the subsets of the networks that were activated to provide support after fifty years of random disasters. They show qualitative differences for the different disaster scenarios measured by path length, degree, clustering coefficient, and number of cycles.     

与甘蓝型油菜重要经济性状有关的DNA克隆在拟南芥遗传图谱中的整合

拟南芥与油菜同属十字花科植物芸寡族,亲缘关系很近,基因组间的同源性很高,在用拟南芥EST克隆和油菜DNA克隆作探针定位了甘蓝型油菜一系列重要性状的基础上,对25个与油菜雄性不育恢复基因,硼高效利用基因,抗菌核病QTL及油菜种间杂种营养优势相关联的克隆进行了测序,在拟南芥基因组数据库中寻找到与这25个克隆高度同源的序列,根据这些高度同源序列在拟南芥染色体上的相位位置,将油菜DNA克隆整合到了拟南芥遗传图谱上,其中油菜硼高效基因BE1两侧的标记克隆整合在拟南芥第一染色体长臂一个较小的区段内,以该目标区段内的拟南芥EST克隆PA24为探针对甘蓝型油菜基因组比较作图,将该克隆定位在油菜连锁图BE1两侧标记之间,表明了利用基因组间的相互比较作图来精细定位芸薹属作物重要基因的可能性。     

Robustness of the p53 network and biological hackers

The p53 protein interaction network is crucial in regulating the metazoan cell cycle and apoptosis. Here, the robustness of the p53 network is studied by analyzing its degeneration under two modes of attack. Linear Programming is used to calculate average path lengths among proteins and the network diameter as measures of functionality. The p53 network is found to be robust to random loss of nodes, but vulnerable to a targeted attack against its hubs, as a result of its architecture. The significance of the results is considered with respect to mutational knockouts of proteins and the directed attacks mounted by tumour inducing viruses.     

Increasing erucic acid content through combination of endogenous low polyunsaturated fatty acids alleles with Ld-LPAAT + Bn-fae1 transgenes in rapeseed (Brassica napus L.)

High erucic acid rapeseed (HEAR) oil is of interest for industrial purposes because erucic acid (22:1) and its derivatives are important renewable raw materials for the oleochemical industry. Currently available cultivars contain only about 50% erucic acid in the seed oil. A substantial increase in erucic acid content would significantly reduce processing costs and could increase market prospects of HEAR oil. It has been proposed that erucic acid content in rapeseed is limited because of insufficient fatty acid elongation, lack of insertion of erucic acid into the central sn-2 position of the triaclyglycerol backbone and due to competitive desaturation of the precursor oleic acid (18:1) to linoleic acid (18:2). The objective of the present study was to increase erucic content of HEAR winter rapeseed through over expression of the rapeseed fatty acid elongase gene (fae1) in combination with expression of the lysophosphatidic acid acyltransferase gene from Limnanthes douglasii (Ld-LPAAT), which enables insertion of erucic acid into the sn-2 glycerol position. Furthermore, mutant alleles for low contents of polyunsaturated fatty acids (18:2 + 18:3) were combined with the transgenic material. Selected transgenic lines showed up to 63% erucic acid in the seed oil in comparison to a mean of 54% erucic acid of segregating non-transgenic HEAR plants. Amongst 220 F₂ plants derived from the cross between a transgenic HEAR line and a non-transgenic HEAR line with a low content of polyunsaturated fatty acids, recombinant F₂ plants were identified with an erucic acid content of up to 72% and a polyunsaturated fatty acid content as low as 6%. Regression analysis revealed that a reduction of 10% in polyunsaturated fatty acids content led to a 6.5% increase in erucic acid content. Results from selected F₂ plants were confirmed in the next generation by analysing F₄ seeds harvested from five F₃ plants per selected F₂ plant. F₃ lines contained up to 72% erucic acid and as little as 4% polyunsaturated fatty acids content in the seed oil. The 72% erucic acid content of rapeseed oil achieved in the present study represents a major breakthrough in breeding high erucic acid rapeseed.