Signal peptide for protein secretion directing glycophospholipid membrane anchor attachment

Decay accelerating factor (DAF) is anchored to the plasma membrane by a glycophospholipid (GPI) membrane anchor covalently attached to the COOH-terminus of the protein. A hydrophobic domain located at the COOH-terminus is required for anchor attachment; DAF molecules lacking this domain are secreted. Replacement of the COOH-terminal hydrophobic domain with a signal peptide that normally functions in membrane translocation, or with a random hydrophobic sequence, results in efficient and correct processing, producing GPI-anchored DAF on the cell surface. The structural requirements for GPI anchor attachment and for membrane translocation are therefore similar, presumably depending on overall hydrophobicity rather than specific sequences.     

Osmotic swelling of phospholipid vesicles causes them to fuse with a planar phospholipid bilayer membrane

Fusion of phospholipid vesicles with planar bilayer membranes occurs if the vesicles that contact the planar membrane swell osmotically after the replacement in their medium of an impermeant solute by a permeant one. This finding directly demonstrates that osmotic swelling is a driving force for vesicle-planar membrane fusion. The method used to induce vesicle swelling and fusion may have relevance for biological systems.     

高铜对山羊红细胞膜磷脂组分和膜流动性的影响

为了探讨高铜对山羊红细胞膜磷脂组成及膜流动性的影响及机制,以体外培养山羊红细胞为模型,通过加入不同浓度硫酸铜溶液,检测了红细胞膜的磷脂组分和细胞流动性。结果表明,加铜组山羊红细胞膜随铜浓度的增加PE的含量低于对照组,PS与SM的含量高于对照组;红细胞膜流动性明显降低。由此可知,高铜可引起膜磷脂组分含量的改变与膜流动性的...     

A proposed framework for accelerating technology trajectories in agriculture: a case study in China

Precision agriculture (PA) technologies have great potential for promoting sustainable intensification of food production, ensuring targeted delivery of agricultural inputs, and hence food security and environmental protection. The benefits of PA technologies are applicable across a broad range of agronomic, environmental and rural socio-economic contexts globally. However, farmer and land-manager adoption in low to middle income countries has typically been slower than that observed in more affluent countries. China is currently engaged in the process of agricultural modernisation to ensure food security for its 1.4 billion population and has developed a portfolio of policies designed to improve food security, while simultaneously promoting environmental protection. Particular attention has been paid to the reduction of agricultural inputs such as fertilisers and pesticides. The widespread adoption of PA technologies across the Chinese agricultural landscape is central to the success of these policies. However, socio-economic and cultural barriers, farm scale, (in particular the prevalence of smaller family farms) and demographic changes in the rural population, (for example, the movement of younger people to the cities) represent barriers to PA adoption across China. A framework for ensuring an acceptable and accelerated PA technology trajectory is proposed which combines systematic understanding of farmer and end-user priorities and preferences for technology design throughout the technology development process, and subsequent end-user requirements for implementation (including demonstration of economic and agronomic benefits, and knowledge transfer). Future research will validate the framework against qualitative and quantitative socio-economic, cultural and agronomic indicators of successful, or otherwise, PA implementation. The results will provide the evidence upon which to develop further policies regarding how to secure sustainable food production and how best to implement PA in China, as well as practical recommendations for optimising end-user uptake.     

乡村旅游推动新农村建设的模式与政策取向

乡村旅游对提高农民收入、增加农民就业、改善乡村环境、保护乡村文化遗产、提升农民素质有重要作用。本文在借鉴世界旅游组织成员国先进经验的基础上,通过总结乡村旅游推动社会主义新农村建设的规律,探索出乡村旅游开发的最佳模式——政府扶持、社区主导的产业化开发模式（CBD模式）,最后结合新农村建设的目标提出政府的行动方案和对策。     

A mechanism for surface attachment in spores of a plant pathogenic fungus

Rice blast disease is caused by a fungus that attacks all above-ground parts of the rice plant. In a study of the means by which the fungus attaches to the hydrophobic rice leaf surface, it was found that spores(conidia) of the rice blast fungus Magnaporthe grisea have a mechanism for immediate and persistent attachment to various surfaces, including Teflon. This attachment occurs at the spore apex and is blocked by the addition of the lectin concanavalin A. Microscopy of hydrated conidia shows that a spore tip mucilage that binds concanavalin A is expelled specifically from the conidial apex before germ tube emergence. Ultrastructural analysis of dry conidia shows a large periplasmic deposit, presumably spore tip mucilage, at the apex. The results indicate a novel mechanism for the attachment of phytopathogenic fungal spores to a plant surface.     

Role of the nonsense-mediated decay factor hUpf3 in the splicing-dependent exon-exon junction complex

Nonsense-mediated messenger RNA (mRNA) decay, or NMD, is a critical process of selective degradation of mRNAs that contain premature stop codons. NMD depends on both pre-mRNA splicing and translation, and it requires recognition of the position of stop codons relative to exon-exon junctions. A key factor in NMD is hUpf3, a mostly nuclear protein that shuttles between the nucleus and cytoplasm and interacts specifically with spliced mRNAs. We found that hUpf3 interacts with Y14, a component of post-splicing mRNA-protein (mRNP) complexes, and that hUpf3 is enriched in Y14-containing mRNP complexes. The mRNA export factors Aly/REF and TAP are also associated with nuclear hUpf3, indicating that hUpf3 is in mRNP complexes that are poised for nuclear export. Like Y14 and Aly/REF, hUpf3 binds to spliced mRNAs specifically ( approximately 20 nucleotides) upstream of exon-exon junctions. The splicing-dependent binding of hUpf3 to mRNAs before export, as part of the complex that assembles near exon-exon junctions, allows it to serve as a link between splicing and NMD in the cytoplasm.     

秸秆快速腐熟试验研究

采用腐秆灵进行秸秆快速腐熟试验。结果表明 :其全氮、全磷和全钾平均提高 1 0 1个百分点、 0 18个百分点和 1 39个百分点 ,粗有机物提高 1 2 1个百分点 ,每公顷秸秆堆肥可获纯收入 14 0 0～ 2 0 0 0元 ,是一项有效解决农村秸秆焚烧问题 ,切实保护环境 ,广开农业有机肥源的实用技术。     

云杉强化育苗技术的研究现状和展望

云杉属Picea是世界重要工业用材树种,其育苗的瓶颈在于苗期和幼林期生长慢,严重影响其遗传评价进程.系统阐述了近年来国内外对云杉及针叶树种塑料大棚及温室强化快速育苗方面的研究进展,论述了光照、温度、湿度、水分、肥料等影响云杉快速育苗的因素并对这些影响因素进行了深入分析.补光处理对云杉播种育苗有显著影响,通过光照处理,可以阻滞云杉的早期封顶.根区温度也是影响云杉生长的一个非常重要的因素,采用强化育苗技术可大大缩短育苗周期,使苗木提早出圃.最后展望了今后我国在云杉强化育苗方面需要开展的研究工作.参34     

Correction of a defect in mammalian GPI anchor biosynthesis by a transfected yeast gene

Glycosylphosphatidylinositol (GPI) serves as a membrane anchor for a large number of eukaryotic proteins. A genetic approach was used to investigate the biosynthesis of GPI anchor precursors in mammalian cells. T cell hybridoma mutants that cannot synthesize dolichol-phosphate-mannose (Dol-P-Man) also do not express on their surface GPI-anchored proteins such as Thy-1 and Ly-6A. These mutants cannot form mannose-containing GPI precursors. Transfection with the yeast Dol-P-Man synthase gene rescues the synthesis of both Dol-P-Man and mannose-containing GPI precursors, as well as the surface expression of Thy-1 and Ly-6A, suggesting that Dol-P-Man is the donor of at least one mannose residue in the GPI core.     

葡萄酒人工催陈研究进展

对葡萄酒人工催陈的方法、原理、应用以及存在的问题进行了论述.     

高校毕业生创业带动就业机制的构建研究

从高校毕业生创业带动就业的理论和实践出发,阐述了高校毕业生创业带动就业的结构框架及模式,提出构建政府、高校、社会"三位一体"长效机制,创业政策扶持、创业培训指导、创业资金资助、创业服务咨询"四位一体"运行机制,社会联动机制和创业评价机制等四个层面的具体措施。     

基于乘客延误的信号交叉口配时优化模型

研究无公交专用信号的信号交叉口乘客延误的优化问题.以HCM2000中的信号交叉口延误公式和Dual Ring信号模式为基础,考虑公交车辆载客率较高的特性,建立了基于乘客延误的信号交叉口配时优化模型,并利用协调变换方法对模型进行改进,使得模型能够采用经典的广义既约梯度法(GRG)进行优化求解.运用本文模型进行实例分析,分析表明,在较高流量饱和度和公交车混入率的情况下,采用本文模型可以降低交叉口乘客人均延误10%以上.     

钙对果蔬采后腐烂的控制及作用

综述了采后钙处理对果蔬腐烂的控制,钙处理的方法及影响因素。钙的防腐机制在于对果蔬采后腐烂的控制,保持细胞壁的结构与功能,增强果实硬度,降低细胞壁降解酶的活性,抑制呼吸,降低乙烯生成量,保持细胞膜的完整性,激活体内的某些氧化酶,诱导合成植保素,作为信号分子,调节细胞功能。     

Stimulation of phospholipase C-gamma 1 membrane association by epidermal growth factor

Epidermal growth factor (EGF) treatment of A-431 epidermoid carcinoma cells elicited a redistribution of phospholipase C-gamma 1 (PLC-gamma 1) from a predominantly cytosolic localization to membrane fractions. The temporal coincidence of this redistribution with EGF stimulation of inositol phosphate formation and EGF increased phosphorylation of PLC-gamma 1 suggests that the membrane association of PLC-gamma 1 is a significant event in second messenger transduction.     

加快天津新一轮农业结构调整的几点思考

鉴于农业结构调整是一个动态概念，本文针对新世纪农业和农村经济发展的趋势和特点，对天津搞好新一轮农业结构调整的思路和目标进行了重新界定，并从六个方面试析了今后调整的重点，从而在此基础上提出了一些对策建议。     

加快龙山县渔业经济发展的对策探讨

对龙山县渔业发展历史与现状进行了调查研究,揭示与剖析了龙山渔业在现代化建设与发展方面存在的问题,提出龙山渔业现代化发展的基本思路及加快渔业经济发展的可行性建议。     

加快发展梧州市特色农产品产业化的研究

特色农产品要比一般性农产品具有明显的比较优势．如果能通过产业化的发展则会产生更大的效益。发展特色农产品产业化是梧州市区域经济发展的重要基础。明确发展梧州市特色农产品产业化的指导思想，依托本地自然资源和区位优势，因地制宜地做好特色农产品产业化模式选择与发展规划，加强特色农产品产前、产中、产后服务保障网络建设．形成具有本地特色的产业链和产品体系．能够极大提高梧州市特包农产品竞争力和综合生产效益。