高梁抗蚜研究进展

高粱(Sorghum bicolour)是世界上最重要的粮食、饲料、酿造和能源作物之一,也是C4植物研究的模式植物.蚜虫是农业生产上的重要害虫,几乎危害所有的栽培作物.危害高粱的蚜虫主要包括高粱蚜(Melanaphis sacchan)、麦二叉蚜(Schizaphis graminum)和玉米蚜(Rhopalosiphum maidis).高粱的抗蚜资源尚不丰富且缺乏深入系统的研究.目前研究较多的是麦二叉蚜的抗性遗传方面,已定位20个抗性QTLs,单一QTL对抗性差异贡献率最高可达80.3％,对高粱蚜和玉米蚜的研究尚需进一步加强.高粱的理化特性与其抗蚜性能相关,故可与育种实践相结合.高粱和蚜虫(Acyrthosiphon pisum)的全基因组测序工作已经完成,这将有助于蚜虫-植物间的相互作用关系及植物对蚜虫的抗性机制研究.目前已克隆到2个抗蚜基因,且多个抗蚜基因(位点)已被定位在染色体上.该文重点综述了上述研究成果并对高粱抗蚜的研究前景进行了展望.     

Effects of Revegetation on Soil Microbial Biomass,Enzyme Activities,and Nutrient Cycling on the Loess Plateau in China

Revegetation is a traditional practice widely used for soil and water conservation on the Loess Plateau in China. However, there has been a lack of reports on soil microbial–biochemical indices required for a comprehensive evaluation of the success of revegetation systems. In this study, we examined the effects of revegetation on major soil nutrients and microbial–biochemical properties in an artificial alfalfa grassland, an enclosed natural grassland, and an artificial shrubland (Caragana korshinskii), with an abandoned cropland as control. Results showed that at 0–5, 5–20, and 20–40 cm depths, soil organic carbon, alkaline extractable nitrogen and available potassium were higher in natural grassland and artificial shrubland compared with artificial grassland and abandoned cropland. Soil microbial biomass C (Cmic) and phosphorous (Pmic) substantially decreased with depth at all sites, and in abandoned cropland was significantly lower than those of natural grassland, artificial grassland, and artificial shrubland at the depth of 0–5 cm. Soil microbial biomass N (Nmic) was higher in artificial shrubland and abandoned cropland compared with that in natural and artificial grasslands. Both Cmic and Pmic were significantly different between the 23‐year‐old and the 13‐year‐old artificial shrublands at the 0–5 cm depth. The activities of soil invertase, urease, and alkaline phosphatase in natural grassland and artificial shrubland were higher than those in artificial grassland and abandoned cropland. This study demonstrated that the regeneration of both natural grassland and artificial shrubland effectively preserved and enhanced soil microbial biomass and major nutrient cycling, thus is an ecologically beneficial practice for recovery of degraded soils on the Loess Plateau.     

Protein-protein interaction site predictions with three-dimensional probability distributions of interacting atoms on protein surfaces

Protein-protein interactions are key to many biological processes. Computational methodologies devised to predict protein-protein interaction (PPI) sites on protein surfaces are important tools in providing insights into the biological functions of proteins and in developing therapeutics targeting the protein-protein interaction sites. One of the general features of PPI sites is that the core regions from the two interacting protein surfaces are complementary to each other, similar to the interior of proteins in packing density and in the physicochemical nature of the amino acid composition. In this work, we simulated the physicochemical complementarities by constructing three-dimensional probability density maps of non-covalent interacting atoms on the protein surfaces. The interacting probabilities were derived from the interior of known structures. Machine learning algorithms were applied to learn the characteristic patterns of the probability density maps specific to the PPI sites. The trained predictors for PPI sites were cross-validated with the training cases (consisting of 432 proteins) and were tested on an independent dataset (consisting of 142 proteins). The residue-based Matthews correlation coefficient for the independent test set was 0.423; the accuracy, precision, sensitivity, specificity were 0.753, 0.519, 0.677, and 0.779 respectively. The benchmark results indicate that the optimized machine learning models are among the best predictors in identifying PPI sites on protein surfaces. In particular, the PPI site prediction accuracy increases with increasing size of the PPI site and with increasing hydrophobicity in amino acid composition of the PPI interface; the core interface regions are more likely to be recognized with high prediction confidence. The results indicate that the physicochemical complementarity patterns on protein surfaces are important determinants in PPIs, and a substantial portion of the PPI sites can be predicted correctly with the physicochemical complementarity features based on the non-covalent interaction data derived from protein interiors.     

三七总RNA提取方法的对比研究

比较利用改进的异硫氰酸胍一步法、异硫氰酸胍高盐法、CTAB法和Thomas’RNA提取法等4种方法提取三七根茎2个部位总RNA的可行性。结果表明,改进的异硫氰酸胍一步法和异硫氰酸胍高盐法能有效地抑制酚类物质、多糖及皂苷等次级代谢产物对总RNA的影响,可从三七根茎中获得质量高、完整性好的总RNA。RT—PCR分析显示提取的总RNA具有反转录活性。这2种方法具有快速、简单、有效的特点。     

我国臭蛙属(两栖纲:蛙科)的系统发育

为探讨臭蛙属的种间亲缘关系与其起源和分化,采用PAUP3．1软件对我国的16种臭蛙的29项分类性状进行系统发育关系的研究。结果表明,臭蛙属物种形成1个单系群,可以划分为4个种组;表明了臭蛙属中国物种间的亲缘关系;无指盘臭蛙和云南臭蛙是本属中最原始的物种,鸭嘴臭蛙等是较特化的物种;原始臭蛙可能起源于横断山区和云南西部高原,贵州高原可能是臭蛙的分化中心;各种组内相近种的地理替代呈南北方向更替,而种组间则呈东西方向更替;原始物种多分布于中国西南部,较进化或特化物种多分布于中国东部和东南部及海岛上;其种组亲缘关系与地理分布格局显示出一致性。     

小鼠层粘连蛋白α5链LG1-3组件的原核表达及多克隆抗体制备

目的:用原核表达的方法获得带有6个His标记的小鼠层粘连蛋白α5链LG1-3组件的重组蛋白,并制备其多克隆抗体。方法:利用RT-PCR技术,从小鼠心肌组织中扩增出小鼠层粘连蛋白α5链LG1-3组件cDNA片段,将该片段与原核表达载体pET-28a连接,构建重组表达质粒pETLG1-3并转化大肠杆菌BL21(DE3)获得重组表达菌株。用IPTG诱导重组大肠杆菌BL21(DE3)/pETLG1-3表达,SDS-PAGE分析表明在相对分子质量60000处有特异性重组蛋白表达条带,并经Western印迹进一步鉴定。用含融合蛋白的聚丙烯酰胺凝胶颗粒免疫家兔,制备抗小鼠层粘连蛋白α5链LG1-3组件多克隆抗体,ELISA方法检测抗体滴度。结果:从小鼠心肌组织中克隆了层粘连蛋白α5链LG3组件的基因,并在大肠杆菌得以表达和纯化;制备了重组蛋白的多克隆抗体,其滴度可达到1∶10240。结论:小鼠层粘连蛋白α5链LG1-3组件重组蛋白及其多克隆抗体的获得,为后续研究其功能打下了基础。     

家蚕色氨酸羟化酶(TRH)基因的克隆及表达特性分析（英文）

5-羟色胺(5-hydroxytryptamine, 5-HT)是生物界广泛分布的信号分子,涉及动物的重要行为。5-HT是色氨酸羟化酶(Tryptophan hydroxylase, TRH)将L-色氨酸羟化为5-羟-L-色氨酸,5-羟-L-色氨酸随即被多巴脱羧酶(Aromatic L-amino acid decarboxylase, DDC)脱羧而成。TRH作为5-HT合成的限速酶,在无脊椎动物神经调控中具有重要地位。鳞翅目昆虫中TRH的功能研究并不多。在家蚕中克隆了家蚕TRH (Bombyx mori TRH, BmTRH)的cDNA序列1667bp,其中包含1632bp的开放读码框(Openreadingframe,ORF)。人类TPH或者果蝇TRH(Drosophila TRH, DmTRH)与BmTRH有高度相似性,尤其BmTRH和DmTRH之间大多数氨基酸保守说明它们在系统发育上的密切关系并可能有相似功能。基因表达分析显示BmTRH主要表达于头部和中枢神经组织,免疫组织化学和Western blotting结果显示BmTRH只存在于神经组织中,即BmTRH可能仅参与家蚕的神经活动。此外,家蚕DDC(B.moridecarboxylase,BmDDC)和蛋白具有TRH活性的苯丙氨酸羟化酶基因(Phenylalanine hydroxylase, BmPAH)也在中枢神经系统中有表达,暗示家蚕神经系统5-HT的合成与果蝇中不同,可能有两种不同的调控机制。