谷氨酸棒杆菌代谢芳烃过程中β-酮己二酸途径中原儿茶酸支路的分子基础

虽然在格蓝氏阴性菌中酮己二酸途径的原儿茶酸支路研究较多,但在格蓝氏阳性菌中的研究很少。本实验中,利用原儿茶酸、对甲酚和4-羟基苯甲酸作为惟一碳源和能源培养谷氨酸棒杆菌,酶活测定表明有原儿茶酸3,4-双加氧酶存在。对基因组数据分析表明在ncg12314-ncg12315位点可能编码原儿茶酸3,4-双加氧酶,ncg12314/ncg12315分别是两个连续的阅读框,采用PCR方法克隆了这两个基因,并在大肠杆菌中表达,测得原儿茶酸3,4－双加氧酶活性,进一步把这两个基因从谷氨酸棒杆菌中敲除,突变株失去了利用原儿茶酸、对甲酚和4-羟基苯甲酸的能力,同时,原儿茶酸3,4-双加氧酶活性消失。原儿茶酸3,4-双加氧酶由α-和β-两个亚基组成,基因同源性比较表明ncg12314/ncg12315分别与α-和β-两个亚基的编码基因同源。这些结果清楚地证明了ncg12314/ncg12315编码原儿茶酸3,4-双加氧酶的两个亚基。通过对谷氨酸棒杆菌基因组分析,发现了参与该芳烃代谢途径的其他基因。本项研究对揭示微生物尤其是格蓝氏阳性菌中芳烃代谢的遗传多样性,提供了新的依据。     

环链棒束孢菌株培养特征、致病性及遗传变异研究

为筛选一种对小菜蛾有高致病力的杀虫真菌,对来自不同地域的环链棒束孢菌株的培养特征尤其是孢梗束形成、对小菜蛾的致病性和基于5.8S-ITS nrDNA构建的系统发育等进行分析。结果表明,供试菌株的培养性状可分为3个类型：孢梗束浓密型、孢梗束稀疏型和不产孢梗束型。孢梗束浓密型对小菜蛾的致病性最高,平均达到88.9%,其中XS.1菌株,对小菜蛾幼虫的致死率达到98%;孢梗束稀疏型次之,为68.4%;不产孢梗束型最差,仅35%。系统发育聚类树分析表明,在环链棒束孢菌株中,致病性较高的菌株,如XS.1,XS.2和SL.7等聚在一亚分支内,致病性低的菌株8.02和468.10聚在一起;不产孢梗束的两个菌株8.02和468.10聚在一个亚支。这些结果表明环链棒束孢菌株间具有明显的种内遗传变异性。孢梗束形成与小菜蛾的致病死亡率有相关性。孢梗束的形成可作为高致病性菌株选择的一个重要指标。     

Research on characteristics of biomass distribution in urban forests of Shanghai metropolis based on remote sensing and spatial analysis

Aims
Monitoring and quantifying the biomass and its distribution in urban trees and forests are crucial to understanding the role of vegetation in an urban environment. In this paper, an estimation method for biomass of urban forests was developed for the Shanghai metropolis, China, based on spatial analysis and a wide variety of data from field inventory and remote sensing.
Methods
An optimal regression model between forest biomass and auxiliary variables was established by stepwise regression analysis. The residual value of regression model was computed for each of the sites sampled and interpolated by Inverse-distance weighting (IDW) to predict residual errors of other sites not subjected to sampling. Forest biomass in the study area was estimated by combining the regression model based on remote sensing image data and residual errors of spatial distribution map. According to the distribution of plantations and management practices, a total of 93 sample plots were established between June 2011 and June 2012 in the Shanghai metropolis. To determine a suitable model, several spectral vegetation indices relating to forest biomass and structure such as normalized difference vegetation index (NDVI), ratio vegetation index (RVI), difference vegetation index (DVI), soil-adjusted vegetation index (SAVI), and modified soil-adjusted vegetation index (MSAVI), and new images synthesized through band combinations such as the sum of TM2, TM3 and TM4 (denoted Band 234), and the sum of TM3, TM4 and TM5 (denoted Band 345) were used as alternative auxiliary parameters .
Important findings
The biomass density in urban forests of the Shanghai metropolis varied from 15 to 120 t·hm^-2. The higher densities of forest biomass concentrated mostly in the urban areas, e.g. in districts of Jing’an and Huangpu, mostly ranging from 35 to 70 t·hm^-2. Suburban localities such as the districts of Jiading and Qingpu had lower biomass densities at around 15 to 50 t·hm^-2. The biomass density of Cinnamomum camphora trees across the Shanghai metropolis varied between 20 and 110 t·hm^-2. The spatial biomass distribution of urban forests displayed a tendency of higher densities in northeastern areas and lower densities in southwestern areas. The total biomass was 3.57 million tons (Tg) for urban forests and 1.33 Tg for C. camphora trees. The overall forest biomass was also found to be distributed mostly in the suburban areas with a fraction of 93.9%, whereas the urban areas shared a fraction of only 6.1%. In terms of the areas, the suburban and urban forests accounted for 95.44% and 4.56%, respectively, of the total areas in the Shanghai metropolis. Among all the administrative districts, the Chongming county and the new district of Pudong had the highest and the second highest biomass, accounting for 20.1% and 19.18% of the total forest biomass, respectively. In contrast, the Jing’an district accounted for only 0.11% of the total forest biomass. The root-mean-square error (RMSE), mean absolute error (MAE) and mean relative error (MRE) of the model for estimating urban forest biomass in this study were 8.39, 6.86 and 24.22%, respectively, decreasing by 57.69%, 55.43% and 64.00% compared to the original simple regression model and by 62.21%, 58.50%, 65.40% compared to the spatial analysis method. Our results indicated that a more efficient way to estimate urban forest biomass in the Shanghai metropolis might be achieved by combining spatial analysis with regression analysis. In fact, the estimated results based on the proposed model are also more comparable to the up-scaled forest inventory data at a city scale than the results obtained using regression analysis or spatial analysis alone.     

人肝细胞癌预后不良相关基因的生物信息学分析及其临床意义

目的:筛选肝细胞癌(HCC)预后不良相关基因,并探讨其临床意义。方法:在基因表达综合数据库(GEO)中获取符合分析条件的肝细胞癌全基因组表达谱数据并分析得到差异表达基因(DEGs),再运用生物学信息注释及可视化数据库 (DAVID) 和蛋白相互作用数据库 (String) 分别进行功能富集分析和蛋白质互作用网络的构建。利用癌症基因组图谱数据库(TCGA)和Cox比例风险回归模型对相关差异基因进行预后分析。结果:找到一个符合条件的人类HCC数据库 (GSE84402),共筛选出1141个差异表达基因(DEGs),其中上调基因720个,下调基因421个。基因功能富集分析和蛋白质互作用分析结果显示CDK1、CDC6、CCNA2、CHEK1、CENPE 、PIK3R1、RACGAP1、BIRC5、KIF11和CYP2B6为HCC预后的关键基因。TCGA数据库和Cox回归模型分析显示CDC6、PIK3R1、RACGAP1和KIF11的表达升高,CENPE的表达降低与HCC预后不良密切相关。结论:CDC6、CENPE、PIK3R1、RACGAP1和KIF11可能和HCC的预后不良相关,可作为未来HCC预后研究的参考标志物。     

使用SPSS线性回归实现通径分析的方法

由于通径分析可以将因变量与自变量的相互影响(相关系数)分解为直接影响(通径系数)和间接影响(间接通径系数),因此在遗传学等领域受到广泛的重视。目前在软件实现方法上,一方面缺乏必要的正态性检验,另一方面通径系数及间接相关系数计算步骤过于繁琐,限制通径分析的教学和使用。在应用中,我们注意到通过SPSS的线性回归"Linear"程序可以一次性获得计算通径系数的全部数据,从而简化通径分析的步骤。     

基于卷积神经网络及气象要素回归法的地表死可燃物含水率预测模型

地表可燃物含水率是森林火险等级和火行为变化的重要指标,其预测模型对于火险预测、火灾管理等具有显著作用。本研究基于蒙古栎及樟子松林地的野外气象因子以及地表死可燃物含水率数据,进行气象因子随机森林相对重要性排序以及皮尔逊相关性分析,并使用深度学习中的卷积神经网络以及气象要素回归法预测可燃物含水率。结果表明：野外蒙古栎的可燃物含水率显著高于樟子松。随机森林结果表明,对于可燃物含水率具有显著作用的因子排列顺序从大到小为湿度、温度、降雨、风速、太阳辐射;相关性分析表明,当日的温度、湿度、降雨对于可燃物含水率具有显著影响,同时,气象因子之间也存在一定的相关性。卷积神经网络模型对于蒙古栎及樟子松林地表可燃物含水率的预测R²分别为0.928、0.905,平均绝对误差(MAE)分别为6.1%、8.1%,平均相对误差(MRE)分别为8.9%、4.2%;气象要素回归法的R²分别为0.495、0.525,MAE分别为30.5%、39.5%,MRE分别为52.1%、32.6%,卷积神经网络模型精度显著高于气象要素回归法。研究表明,深度学习的卷积神经网络能够为今后的可燃...     

产谷氨酸棒杆菌B9和T6—13的原生质体融合

棒杆菌Ｂ９和Ｔ６—１３两菌株经ＵＶ变处理得到Ｂ９—２（ＳｍＲ）和Ｔ６—１３—３（ＲｉｆＲ）两菌株,以此两菌株做为出发菌株。将对数前期的培养细胞经青霉素予处理及酶解制备原生质体,用４０％ＰＥＧ６０００为助融剂,进行原生质体融合。用间接法检出具有Ｓｍ、Ｒｉｆ抗性的融合子。融合频率为６．５５×１０－６－１．６４×１０－５,融合子双抗性稳定,产谷氨酸,经摇瓶实验筛选出一株产谷氨酸明显高于亲本的融合子ｆｕ３６。     

收入增长对营养需求的异质性影响研究

利用国家统计局城镇住户调查数据,运用非参数估计方法分析了收入与营养需求间的关系,结果表明,收入水平与营养需求间的关系呈非线性。进一步运用工具变量分位数回归实证研究了在不同营养摄入水平上收入对营养摄入的影响,结果表明,收入对营养需求的影响在不同营养摄入水平上存在异质性,处于高营养摄入区域家庭的营养收入弹性小于处于低营养摄入区域家庭的营养弹性。因此,针对不同的人群,应采取差异化的营养政策,同时应重视宣传教育,引导科学合理膳食。     

密码对的偏爱与基因组进化的相关性分析

以5种真核、15种细菌、10种古菌生物基因组为样本,对密码对使用偏好性指标Г与密码对随基因组进化的指标α之间作线性分析,发现部分密码对的r值与α之间有显著的线性关系;密码子第三位点与紧邻密码子第一位点的双碱基（cP3cAl）使用与基因组进化有关。结果进一步肯定了密码对的使用与基因组进化存在相关性,同时从密码对使用的角度揭示了真核生物、真细菌、古菌的基本差别。     

中国西南山区城市建设用地扩张特征及其驱动机制

理清城市建设用地扩张的驱动机制有利于抑制当前城镇化进程中出现的城市建设用地无序扩张现象.本研究以西南山区的410个县(区)为对象,分析了其2000-2015年城市建设用地扩张特征,并通过多元线性回归探索西南山区城市建设用地扩张的驱动因子及驱动机制.结果 表明:(1) 2000-2015年西南山区各县(区)城市建设用地扩...