地衣芽孢杆菌耐高温α-淀粉酶基因的克隆、烟草瞬时表达及转化拟南芥的研究

从地衣芽孢杆菌(Bacillus licheniformis)中克隆到耐高温α-淀粉酶基因全长, 构建了原核表达载体, 转入大肠杆菌(Escherichia coli)中, 使用IPTG于28°C诱导6小时后, 通过SDS-PAGE检测到目的蛋白, 分子量约为55 kDa, 并通过酶活力检测实验证明该蛋白具有耐高温α-淀粉酶活性。同时构建了该基因融合GFP的植物表达载体, 通过农杆菌(Agro- bacterium tumefaciens)介导瞬时转化烟草(Nicotiana tabacum)下表皮细胞并在荧光显微镜下观察, 发现在烟草下表皮细胞的细胞质和液泡中均有绿色荧光。使用I₂-KI溶液对乙醇脱色后的烟草叶片进行染色, 显色反应表明在烟草中表达的耐高温α-淀粉酶具有酶活性。最后, 采用农杆菌介导的花蕾浸泡法将重组载体转化到拟南芥(Arabidopsis thaliana)中, 筛选到稳定遗传的耐高温α-淀粉酶基因的拟南芥纯合子。研究结果为后期开展表达耐高温α-淀粉酶的转基因植物的相关研究奠定了实验基础。     

黑胸散白蚁末龄若虫蜕皮羽化行为观察

【目的】了解黑胸散白蚁Reticulitermes chinensis Snyder末龄若虫的蜕皮羽化行为。【方法】室内恒温(26±0.5)℃恒湿(75%±5%)饲养黑胸散白蚁末龄若虫,间隔一定时间进行观察记录。【结果】黑胸散白蚁末龄若虫蜕皮羽化时间持续2~8 h。蜕皮一般从末龄若虫胸腹部交界处背部开始破裂,从腹末、翅末、足端、口器末端或触角端脱落,50%以上的正常羽化蜕皮是从腹末端脱落。初始羽化成虫为白色,随后身体和翅的颜色逐渐加深和变黑,羽化8~12 h后,虫体整体颜色变为黑色。室内观察结果还表明,34.7%的末龄若虫无法正常羽化。【结论】黑胸散白蚁末龄若虫蜕皮羽化持续时间较短,蜕皮一般是从胸腹部交界处背部开始破裂,但可从不同部位脱落,且蜕皮羽化行为容易受到外界环境的影响。     

花粒期光照对夏玉米干物质积累和养分吸收的影响

选用登海605(DH605)为试验材料,在大田条件下通过花粒期遮阴(S)和增光(L)研究不同光照对花后夏玉米产量、干物质积累和氮、磷、钾养分吸收与运转特性的影响.结果表明: 遮阴后夏玉米产量、干物质积累量及氮、磷、钾养分吸收量均显著降低;而增光有利于夏玉米干物质积累量及氮、磷、钾养分吸收量和产量的提高.2011-2013年,遮阴处理的产量较对照(自然光下)分别降低了59.4%、79.0%、60.6%;增光后产量分别增加16.3%、12.9%、6.8%.遮阴对干物质积累的影响大于其对植株氮、磷吸收量的影响,植株体内氮、磷等养分含量有所上升,而钾吸收量的下降幅度大于干物质积累,钾素相对含量降低,氮、磷、钾向籽粒的分配比例降低.增光后干物质积累和氮、磷吸收量显著上升,但对氮、磷吸收的影响更大;增光条件下,氮、磷、钾等养分向籽粒的分配比例增加.
     

杜仲法尼烯基焦磷酸合酶基因cDNA全长的克隆与序列分析

采用RT-PCR法,从杜仲幼嫩叶片中分离法尼烯基焦磷酸基因c DNA全长序列,克隆并对该基因全长序列进行生物信息学分析。从杜仲嫩叶中共获得两个基因分别命名为Eu FPPs1和Eu FPPs2,测序结果表明两基因开放阅读框分别为1 047 bp和1 029 bp,推测分别可以编码348个和342个氨基酸残基,在线预测表明两个蛋白序列均存在两个聚丙烯合酶位点。系统进化分析结果表明,Eu FPPs1和Eu FPPs2分别聚集于不同的分支,它们之间的进化距离为0.352,但是在亲缘关系上均与楤木和人参最近,进化距离分别为0.281、0.287,0.175、0.184。     

重楼活性单体pp-10通过抑制PI3K/Akt通路诱导人胃癌细胞BGC-823凋亡和自噬

目的:探讨重楼/七叶一枝花(Paris polyphylla)的醇提物单体pp-10诱导人胃癌BGC-823细胞凋亡和自噬及其分子机制。方法:采用MTT法和克隆形成抑制实验观察不同浓度的重楼单体pp-10对人胃癌BGC-823细胞的增殖抑制作用;Hoechst33342染色法检测pp-10作用于人胃癌BGC-823细胞后细胞核形态的改变;Annexin V-FITC/PI双染法检测细胞凋亡;Western blotting检测重楼单体pp-10对细胞凋亡和自噬相关蛋白Caspase-3、Caspase-9、(ADP-核糖)聚合酶(PARP)、Bax、Bcl-2、LC3、P62以及PI3K/Akt信号通路相关蛋白(Akt、p-Akt、m TOR、p-m TOR、P70s6k、p-P70s6k)表达的影响。结果:重楼单体pp-10能显著抑制BGC-823细胞的生长,作用呈时间-效应关系及剂量-效应关系;克隆形成抑制实验表明随着pp-10浓度的增加,细胞克隆形成逐渐减少,与对照组相比有显著差异;在荧光显微镜下观察可见其细胞核固缩、边聚、裂解等细胞凋亡形态学变化;流式细胞术检测显示,随着作用药物浓度的增高,其凋亡率逐渐升高;Western blotting结果表明,随着药物浓度的增加,线粒体相关凋亡信号通路蛋白Caspase9、Caspase3及PARP均出现酶切活化条带,细胞促凋亡蛋白Bax的表达水平增加,抗凋亡蛋白Bcl-2减少,自噬相关蛋白Ⅱ型LC3增加,P62蛋白减少,p-Akt蛋白的表达水平下降,Akt下游蛋白p-m Tor、p-p70S6K表达减少。结论:重楼单体pp-10通过抑制BGC-823细胞增殖,诱导细胞凋亡和自噬,与下调P13K/Akt信号通路有关。     

钾长石矿区土壤解钾菌的分离与多样性

目的获得高效钾长石分解细菌及分析钾长石矿区土壤中解钾菌的多样性。方法采集湖南省吉首市钾长石矿区土壤,用钾长石为唯一钾源的选择性培养基筛选分离解钾细菌,采用形态特征观察、生理生化特性检测和基于16S rRNA基因序列的系统发育分析初步鉴定解钾菌株,并测定菌株摇瓶条件下的解钾能力。结果分离获得38株钾长石分解细菌,分别属于13个属,其中13株菌为剑菌属,4株菌为芽胞杆菌属。菌株L17的发酵液中有效钾含量最高,为87.66 mg/L,是对照组的15.8倍。结论钾长石矿区土壤细菌种类有较好的多样性,其中剑菌属和芽孢杆菌属为优势种群,Mitsuaria属的L17解钾能力最强。     

Drastic Layer‐Number‐Dependent Activity Enhancement in Photocatalytic H2 Evolution over nMoS2/CdS (n ≥ 1) Under Visible Light

Exploiting noble‐metal‐free cocatalysts is of huge interest for photocatalytic water splitting using solar energy. As an efficient cocatalyst in photocatalysis, MoS₂ is shown promise as a low‐cost alternative to Pt for hydrogen evolution. Here we report a systematical study on controlled synthesis of MoS₂ with layer number ranging from ≈1 to 112 and their activities for photocatalytic H₂ evolution over commercial CdS. A drastic increase in photocatalytic H₂ evolution is observed with decreasing MoS₂ layer number. Particularly for the single‐layer (SL) MoS₂, the SL‐MoS₂/CdS sample reaches a high H₂ generation rate of ≈2.01 × 10^?3m h^?1 in Na₂S–Na₂SO₃ solutions and ≈2.59 × 10^?3m h^?1 in lactic acid solutions, corresponding to an apparent quantum efficiency of 30.2% and 38.4% at 420 nm, respectively. In addition to the more exposed edges and unsaturated active S atoms, valence band–XPS and Mott–Schottky plots analysis indicate that the SL MoS₂ has the more negative conduction band energy level than the H⁺/H₂ potential, facilitating the hydrogen reduction.     

Seasonally different response of photosynthetic activity to daytime and night‐time warming in the Northern Hemisphere

Over the last century the Northern Hemisphere has experienced rapid climate warming, but this warming has not been evenly distributed seasonally, as well as diurnally. The implications of such seasonal and diurnal heterogeneous warming on regional and global vegetation photosynthetic activity, however, are still poorly understood. Here, we investigated for different seasons how photosynthetic activity of vegetation correlates with changes in seasonal daytime and night‐time temperature across the Northern Hemisphere (>30°N), using Normalized Difference Vegetation Index (NDVI) data from 1982 to 2011 obtained from the Advanced Very High Resolution Radiometer (AVHRR). Our analysis revealed some striking seasonal differences in the response of NDVI to changes in day‐ vs. night‐time temperatures. For instance, while higher daytime temperature (T_max) is generally associated with higher NDVI values across the boreal zone, the area exhibiting a statistically significant positive correlation between T_max and NDVI is much larger in spring (41% of area in boreal zone – total area 12.6 × 10⁶ km²) than in summer and autumn (14% and 9%, respectively). In contrast to the predominantly positive response of boreal ecosystems to changes in T_max, increases in T_max tended to negatively influence vegetation growth in temperate dry regions, particularly during summer. Changes in night‐time temperature (T_min) correlated negatively with autumnal NDVI in most of the Northern Hemisphere, but had a positive effect on spring and summer NDVI in most temperate regions (e.g., Central North America and Central Asia). Such divergent covariance between the photosynthetic activity of Northern Hemispheric vegetation and day‐ and night‐time temperature changes among different seasons and climate zones suggests a changing dominance of ecophysiological processes across time and space. Understanding the seasonally different responses of vegetation photosynthetic activity to diurnal temperature changes, which have not been captured by current land surface models, is important for improving the performance of next generation regional and global coupled vegetation‐climate models.     

First Report of Cucumber mosaic virus Infecting Chinese Mallow in China

The virus in naturally infected, stunted Chinese mallow plants and mosaic leaves was identified as Cucumber mosaic virus (CMV). Six symptomatic plants and one symptomless plant were collected in Chongqing, China. DAS‐ELISA suggested CMV was likely associated with the diseased Chinese mallow. Double‐stranded RNA was extracted from the samples, analysed by RT‐PCR, and the coding sequences of their coat proteins (CPs) were sequenced. The results further confirmed CMV was the pathogen causing Chinese mallow stunted, mosaic disease. The isolate was named CMV‐DXC. The full sequence of CMV‐DXC CP was determined, and it had the highest nucleotide identity (99.4%) of those of CMV‐lily, CMV‐WSJ and CMV‐Hnt, respectively. Phylogenetic analysis shows that CMV‐DXC belongs to CMV subgroup II. To our knowledge, this is the first report of CMV infecting Chinese mallow in China.