中国东北样带的梯度分析及其预测

陆地样带研究已成为国际地圈-生物圈计划(IGBP)全球变化研究的重要手段与热点。中国东北样带(NECT)已被列为IGBP国际全球变化陆地样带之一。该样带在东经112°与130°30＇之间沿北纬43°30＇设置,长约1600km,是一条中纬度温带以降水为驱动因素的梯度,具有由温带针阔叶混交林向温带草原的3个亚地带——草甸草原、典型草原与荒漠草原过渡的空间系列。该样带上有4个生态实验站。在大量的固定样地、实验调查研究资料与数据的基础上给出了样带的初步梯度分析及在全球变化图景下的预测,包括其地理位置、设置意义、地形地貌、气候梯度、土壤类型、植被类型和土地利用格局,一个遥感数据驱动的模型和NPP模型在整个样带上运行过。今后NECT将在生物地球化学循环(水、C、N、P等与痕量气体CO_2、CH_4等)、生态系统结构、功能与动态、生物多样性、土地利用与土地覆盖、动态全球植被模型(DGVM)以及高分辨率遥感数据应用等方面得到加强,将成为我国全球变化与陆地生态系统(GCTE)与其它IGBP核心项目研究的前沿阵地。     

Refolding and purification of recombinant human (Pro)renin receptor from Escherichia coli by ion exchange chromatography

Purification of the recombinant human renin receptor (rhRnR) is a major aspect of its biological or biophysical analysis, as well as structural research. A simple and efficient method for the refolding and purification of rhRnR expressed in Escherichia coli with weak anion‐exchange chromatography (WAX) was presented in this work. The solution containing denatured rhRnR in 8.0 mol/L urea extracted from the inclusion bodies was directly injected into the WAX column. The aggregation was prevented and the soluble form of renatured rhRnR in aqueous solution was obtained after desorption from the column. Effects of the extracting solutions, the pH values and urea concentrations in the mobile phase, as well as the sample size on the refolding and purification of rhRnR were investigated, indicating that the above mentioned factors had remarkable influences on the efficiency of refolding, purification and mass recovery of rhRnR. Under the optimal conditions, rhRnR was successfully refolded and purified simultaneously by WAX in one step within only 30 min. The result was satisfactory with mass recovery of 71.8% and purity of 94.8%, which was further tested by western blotting. The specific binding of the purified rhRnR to recombinant human renin was also determined using surface plasmon resonance (SPR). The association constant of rhRnR to recombinant human renin was calculated to be 3.25 × 10⁸ L/mol, which demonstrated that rhRnR was already renatured and simultaneously purified in one step using WAX. All of the above demonstrate that protein folding liquid chromatography (PFLC) should be a powerful tool for the purification and renaturation of rhRnR. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:864–871, 2014     

Serotonin modulates circadian entrainment in Drosophila

Entrainment of the Drosophila circadian clock to light involves the light-induced degradation of the clock protein timeless (TIM). We show here that this entrainment mechanism is inhibited by serotonin, acting through the Drosophila serotonin receptor 1B (d5-HT1B). d5-HT1B is expressed in clock neurons, and alterations of its levels affect molecular and behavioral responses of the clock to light. Effects of d5-HT1B are synergistic with a mutation in the circadian photoreceptor cryptochrome (CRY) and are mediated by SHAGGY (SGG), Drosophila glycogen synthase kinase 3beta (GSK3beta), which phosphorylates TIM. Levels of serotonin are decreased in flies maintained in extended constant darkness, suggesting that modulation of the clock by serotonin may vary under different environmental conditions. These data identify a molecular connection between serotonin signaling and the central clock component TIM and suggest a homeostatic mechanism for the regulation of circadian photosensitivity in Drosophila.     

人SATB1基 5'上游序列的转录激活功能分析

在对人SATB1基因进行生物信息学分析的基础上,采用PCR技术,扩增人基因组DNA中SATB1基因5'上游序列的-2955～-9片段,构建了3个分别由SATB1基因5'上游-2955～-9,-1727～-9和-760～-9序列片段驱动的报告载体-pGL3-SP2946-luc,pGL3-SP1718-luc和pGL3-SP751-luc,分别瞬时转染Jurkat T,K562,U937和HeLa细胞,通过测定荧光素酶的表达活性,观察SATB1基因5'上游序列片段3个删除突变体在不同细胞内活性的差异.结果显示,SATB1上游序列-2955/-9在4种细胞中的转录激活能力为U937>Jurkat T>K562,在HeLa细胞中基本无激活,提示SATB1的转录激活可能具有一定的细胞类型特异性.3种5'删除突变体转录激活性由大至小顺序为-760/-9>-2955/-9>-1727/-9,提示SATB1的核心启动子可能存在于其5'上游序列的-760至-9 bp区域中.     

Insecticidal activity and chemical composition of the essential oil of Artemisia vestita from China against Sitophilus zeamais

In our screening program for new agrochemicals from local wild plants, essential oil of Artemisia vestita Wall (Asteraceae) was found to possess strong insecticidal activity against maize weevil, Sitophilus zeamais Motsch. Essential oil of aerial parts of A. vestita was obtained from hydrodistillation and was investigated by GC and GC–MS. The main components of essential oil were grandisol (40.29%), 1,8-cineol (14.88%) and camphor (11.37%). The essential oil of A. vestita possessed strong fumigant toxicity against S. zeamais adults with a LC₅₀ value of 13.42 mg/L air. The essential oil of A. vestita also showed contact toxicity against S. zeamais adults with a LD₅₀ value of 50.62 mg/adult.     

核苷酸转换因子的特性及其在植物中的研究现状

热激蛋白HSP70是一类细胞必需的具有ATPase活性的分子伴侣。ADP的脱离是HSP70分子伴侣体系能够完成其功能循环的限速步骤,该反应步骤由核苷酸交换因子（NEFs）加速,因此,NEFs是HSP70分子伴侣体系中的一类关键辅助因子。本文总结了有关NEFs的研究成果以及植物NEFs的最新研究进展。     

Terminal amino acids disturb xylanase thermostability and activity

Protein structure is composed of regular secondary structural elements (α-helix and β-strand) and non-regular region. Unlike the helix and strand, the non-regular region consists of an amino acid defined as a disordered residue (DR). When compared with the effect of the helix and strand, the effect of the DR on enzyme structure and function is elusive. An Aspergillus niger GH10 xylanase (Xyn) was selected as a model molecule of (β/α)(8) because the general structure consists of ~10% enzymes. The Xyn has five N-terminal DRs and one C-terminal DR, respectively, which were deleted to construct three mutants, XynΔN, XynΔC, and XynΔNC. Each mutant was ~2-, 3-, or 4-fold more thermostable and 7-, 4-, or 4-fold more active than the Xyn. The N-terminal deletion decreased the xylanase temperature optimum for activity (T(opt)) 6 °C, but the C-terminal deletion increased its T(opt) 6 °C. The N- and C-terminal deletions had opposing effects on the enzyme T(opt) but had additive effects on its thermostability. The five N-terminal DR deletions had more effect on the enzyme kinetics but less effect on its thermo property than the one C-terminal DR deletion. CD data showed that the terminal DR deletions increased regular secondary structural contents, and hence, led to slow decreased Gibbs free energy changes (ΔG(0)) in the thermal denaturation process, which ultimately enhanced enzyme thermostabilities.     

Functional divergence of the duplicated AtKIN14a and AtKIN14b genes: critical roles in Arabidopsis meiosis and gametophyte development

Gene duplication is important for gene family evolution, allowing for functional divergence and innovation. In flowering plants, duplicated genes are widely observed, and functional redundancy of closely related duplicates has been reported, but few cases of functional divergence of close duplicates have been described. Here, we show that the Arabidopsis AtKIN14a and AtKIN14b genes encoding highly similar kinesins are two of the most closely related Arabidopsis paralogs, which were formed by a duplication event that occurred after the split of Arabidopsis and poplar. In addition, AtKIN14a and AtKIN14b exhibit varying degrees of coding sequence divergence. Further genetic studies of plants carrying atkin14a and/or atkin14b mutations indicate that, although these two genes have similar functions, there is clear evidence for functional divergence. Although both genes are important for male and female meiosis, AtKIN14a plays a more critical role in male meiosis than AtKIN14b . Moreover, either one of these two genes is necessary and sufficient for gametophyte development, indicating that they are redundant for this function. Therefore, AtKIN14a and AtKIN14b together play important roles in controlling plant reproductive development. Our results suggest that the AtKIN14a and AtKIN14b genes have retained similar functions in gametophyte development and female meiosis, but have evolved partially distinct functions in male meiosis, with AtKIN14a playing a more substantive role.