Parallels between cytokinesis and retroviral budding: a role for the ESCRT machinery

During cytokinesis, as dividing animal cells pull apart into two daughter cells, the final stage, termed abscission, requires breakage of the midbody, a thin membranous stalk connecting the daughter cells. This membrane fission event topologically resembles the budding of viruses, such as HIV-1, from infected cells. We found that two proteins involved in HIV-1 budding-tumor susceptibility gene 101 (Tsg101), a subunit of the endosomal sorting complex required for transport I (ESCRT-I), and Alix, an ESCRT-associated protein-were recruited to the midbody during cytokinesis by interaction with centrosome protein 55 (Cep55), a centrosome and midbody protein essential for abscission. Tsg101, Alix, and possibly other components of ESCRT-I were required for the completion of cytokinesis. Thus, HIV-1 budding and cytokinesis use a similar subset of cellular components to carry out topologically similar membrane fission events.     

55%耕杰水悬浮剂防除玉米田杂草试验研究

2009年进行了55%耕杰悬浮剂防除玉米田杂草最佳使用剂量、施药适期、及对玉米安全性等使用技术试验。结果表明,55%耕杰悬浮剂125ml/667m2,于玉米2～3叶期兑水喷施,药后50d的总体株防效为81.2%,总体鲜重防效为97.2%,对玉米安全性较好。     

基于WITNESS的农场收获机器系统配备应用仿真研究

目前农场在收获作业中,大多以经验法进行收获机器系统的配备,从而导致因运载机械配备不合理而造成的收获作业延误情况.结合农场在收获作业中存在的问题,对收获机及运载机械相关数据进行实地测量,将农场的收获过程视作物流系统,运用系统仿真的原理,应用系统仿真软件对收获过程进行建模,查找实际生产中收获机与运载机械的配备中存在的问题,...     

55所高校图书馆图书招标采购调查分析

以对全国55所高校图书馆招标采购工作的问卷调查为依据,分析各馆图书招标采购情况、成功经验、存在问题以及解决办法.调查表明：各高校图书馆已经形成稳定的招标采购工作模式;对中英文图书的折扣及中标标准的判定也基本形成共识;但在评标标准、评标细则、合同执行方面存在差异,对图书供应商的评价指标不尽相同.高校图书馆采访人员为适应招标采购的工作模式应当预先制定年度工作计划;与重点出版社建立联系,积极收集重点出版社书目;制定详细的评价指标,并且定期对图书供应商进行评价.     

Bacterial mode of replication with eukaryotic-like machinery in a hyperthermophilic archaeon

Despite a rapid increase in the amount of available archaeal sequence information, little is known about the duplication of genetic material in the third domain of life. We identified a single origin of bidirectional replication in Pyrococcus abyssi by means of in silico analyses of cumulative oligomer skew and the identification of an early replicating chromosomal segment. The replication origin in three Pyrococcus species was found to be highly conserved, and several eukaryotic-like DNA replication genes were clustered around it. As in Bacteria, the chromosomal region containing the replication terminus was a hot spot of genome shuffling. Thus, although bacterial and archaeal replication proteins differ profoundly, they are used to replicate chromosomes in a similar manner in both prokaryotic domains.     

Efficient inhibition of the Alzheimer's disease beta-secretase by membrane targeting

beta-Secretase plays a critical role in beta-amyloid formation and thus provides a therapeutic target for Alzheimer's disease. Inhibitor design has usually focused on active-site binding, neglecting the subcellular localization of active enzyme. We have addressed this issue by synthesizing a membrane-anchored version of a beta-secretase transition-state inhibitor by linking it to a sterol moiety. Thus, we targeted the inhibitor to active beta-secretase found in endosomes and also reduced the dimensionality of the inhibitor, increasing its local membrane concentration. This inhibitor reduced enzyme activity much more efficiently than did the free inhibitor in cultured cells and in vivo. In addition to effectively targeting beta-secretase, this strategy could also be used in designing potent drugs against other membrane protein targets.     

The principles of controlling mechanical structures in agricultural machinery by frequency characteristics

We present a methodology that might be used for analysis and synthesis of executive subsystems in agricultural machines with frequency control over their working processes; this methodology is adapted to specific features of seeds, soils, and operating conditions.     

普草克55%悬浮剂防除麦田杂草试验

普草克 5 5 %悬浮剂不同使用剂量的试验结果表明 :用 1.8L/hm2 即可达到较理想的除草效果和增产效果 ,由于它不含甲、绿黄隆成份 ,对本田及下茬作物均比较安全     

pET-32a载体介导的生长抑制素基因在大肠杆菌中表达

为构建pET-32a-2SS28-SS14和pET-32a-3SS28原核表达质粒并检测其在大肠杆菌中的表达,将两种形式的生长抑制素SS14和SS28基因克隆到pET-32a载体中;酶切及测序鉴定后,采用不同终浓度的IPTG在37℃条件下进行诱导表达。Western blot结果显示:两组分别诱导出分子量大小为28.4 kD和29.8 kD的目的蛋白,不同终浓度的IPTG诱导对目的蛋白的表达量没有明显影响。目的蛋白主要为可溶性蛋白,少数以包涵体形式存在。本研究为生长抑制素基因工程疫苗生产应用奠定了基础。     

自动导航拖拉机的农机具作业精度研究

针对自动导航拖拉机带农机具作业时农机具跟踪误差会被放大的问题,提出了1种能够提高农机具作业精度的拖拉机导航算法。采用路径跟踪误差最小的优化控制方法,研究拖拉机自动导航作业时引起机具误差大的因素及改进方法,设计具有农机具误差项的拖拉机模型预测控制算法,对该算法进行可行性试验及对比试验。试验结果表明采用带机具误差项的算法使农机具横向偏差平均降低了42.36%,横向偏差标准差平均降低了40.91%,航向角最大偏差平均降低了6.11%,航向角偏差标准差平均降低了31.04%。结果表明增加农机具误差项的模型预测控制算法能有效提升农机具的作业精度。     

在线凝胶色谱-气相色谱质谱测定菠菜中55种农药残留

运用在线凝胶色谱-气相色谱质谱联用(GPC-GC/MS)技术,建立一种快速、准确测定菠菜样品中55种农药残留的方法。样品用乙腈提取,经盐析、PSA净化后,使用GPC-GC/MS进行检测。结果表明:各组分分离良好,在0.025、0.05及0.10 mg/kg 3个添加水平,55种农药的回收率在81.3%~106.2%,相对标准偏差均低于10.3%;在0.01~0.5μg/m L浓度范围内,线性关系良好,相关系数均大于0.995 3;55种农药的检出限为0.005~0.5μg/kg。该方法准确、灵敏、快速,可满足对菠菜中55种农药残留的检测需要。     

mgr-mir-9 implicates Meloidogyne graminicola infection in rice by targeting the effector MgPDI

MicroRNAs (miRNAs), a class of small non-coding RNAs, are crucial endogenous gene regulators in a range of animals, including plant-parasitic nematodes. Meloidogyne graminicola is an obligate sedentary endoparasite of rice and causes significant yield losses. A number of studies focused on the roles of M. graminicola effectors during the parasitic process; however, how nematode miRNAs regulate its effectors needs elucidating. In this research, we analyzed a cluster of M. graminicola miRNAs obtained at the second-stage juveniles (J2s) stage that are closely linked to the regulation of M. graminicola effectors. There are 49 767 105 total clean reads obtained from three libraries. A total of 233 known miRNAs and 21 novel miRNAs were identified. Among the known miRNAs, mgr-lin-4, mgr-mir-1, mgr-mir-100, mgr-mir-86, mgr-mir-279, mgr-mir-87, mgr-mir-71, mgr-mir-9, mgr-mir-50, mgr-mir-72, and mgr-mir-34 are the most abundant 11 miRNAs families. Moreover, the expression levels of selected miRNAs were validated by real-time quantitative PCR. We hypothesized that these miRNAs might regulate the expression of secreted effectors during the J2s stage to facilitate its infection. Consistent with this, we found that mgr-mir-9 targets MgPDI, an important M. graminicola effector mRNA. In addition to that, J2s treated with mgr-mir-9 mimics showed down-regulation of MgPDI expression and reduced reproductive ability, alluding mgr-mir-9 is involved in nematode infection. These results provide novel insight into the regulatory functions of M. graminicola miRNAs during the infection and identify miRNAs and their effector targets as potential key management targets to limit parasite survival during the early stages of infection.     

Communication of the position of exon-exon junctions to the mRNA surveillance machinery by the protein RNPS1

In mammalian cells, splice junctions play a dual role in mRNA quality control: They mediate selective nuclear export of mature mRNA and they serve as a mark for mRNA surveillance, which subjects aberrant mRNAs with premature termination codons to nonsense-mediated decay (NMD). Here, we demonstrate that the protein RNPS1, a component of the postsplicing complex that is deposited 5' to exon-exon junctions, interacts with the evolutionarily conserved human Upf complex, a central component of NMD. Significantly, RNPS1 triggers NMD when tethered to the 3' untranslated region of beta-globin mRNA, demonstrating its role as a subunit of the postsplicing complex directly involved in mRNA surveillance.     

关于我国智慧农机产业发展的分析

智慧农机的涌现被视为农业产业升级的关键及制造业智能升级的重点产业之一,在全面分析我国智慧农机发展的产业基础上,从产业发展的经济性制约、农业劳动力结构调整和农业生产组织形式的进一步分化3方面的影响进行探讨,提出了以增效为主的智慧农机发展策略。     

能量天平动圈位移的激光干涉测量研究

为精确测量普朗克常数h,实现能量天平法建立量子质量基准,提出了三轴双频激光外差干涉和折叠式Fabry-Perot(F-P)干涉绝对距离测量相结合的激光干涉测量方法,用于精密测量和定位能量天平装置中沿竖直方向在均匀磁场中运动的互感线圈位移。用三轴双频激光外差干涉精密测量运动线圈的质心位移和姿态,位移测量不确定度为10nm;进而将F-P腔干涉绝对距离测量与外差干涉测量结果进行比对和校准。仿真表明,采用本文方法,当位移测量范围约为30mm时,测量分辨率优于1nm。将该方法运用于真空中线圈位移测量,相对测量不确定度优于1.0×10-9。