Zooming in on the molecular mechanisms of endocytic budding by time-resolved electron microscopy

Endocytic budding implies the remodeling of a plasma membrane portion from a flat sheet to a closed vesicle. Clathrin- and actin-mediated endocytosis in yeast has proven a very powerful model to study this process, with more than 60 evolutionarily conserved proteins involved in fashioning primary endocytic vesicles. Major progress in the field has been made during the last decades by defining the sequential recruitment of the endocytic machinery at the cell cortex using live-cell fluorescence microscopy. Higher spatial resolution has been recently achieved by developing time-resolved electron microscopy methods, allowing for the first time the visualization of changes in the plasma membrane shape, coupled to the dynamics of the endocytic machinery. Here, we highlight these advances and review recent findings from yeast and mammals that have increased our understanding of where and how endocytic proteins may apply force to remodel the plasma membrane during different stages of the process.     

我国连锁超市的规模经济分析我国连锁超市的规模经济分析

随着全球经济的飞速发展,连锁经营已经成为各国零售业普遍采取的经营方式.同时,连锁超市已经逐步成为我国零售业的主流,为我国的经济增长做出了巨大贡献.从规模经济的角度分析了我国连锁超市企业的发展,通过实证分析证实连锁超市确实存在规模经济性,从而为我国连锁超市的健康发展提供一些理论参考.     

福建九龙江河口游离氨基酸的分布规律初探

通过在九龙江河口及厦门西海域的多次航行取样，并对其ＤＦＡＡ含量、ｃｈｌ－ａ含量以及盐度等多种水文因素进行分析．从而得出游离氨基酸含量与海水的物理因素（如混合程度）、盐度、浮游植物生物量等之间的相互关系．而海水中游离氨基酸ＤＦＡＡ含量是引起赤潮的一个主要原因．因此，弄清ＤＦＡＡ含量变化规律．也是预防赤潮发生的重要前提．它对赤潮的预测及防护以及治理都关系甚密．     

Actin-, myosin- and ubiquitin-dependent endocytosis

Endocytosis is a general term that is used to describe the internalization of external and plasma membrane molecules into the cell interior. In fact, several different mechanisms exist for the internalization step of this process. In this review we emphasize the work on the actin-dependent pathways, in particular in the yeastSaccharomyces cerevisiae, because several components of the molecular machinery are identified. In this yeast, the analysis of endocytosis in various mutants reveals a requirement for actin, calmodulin, a type I myosin, as well as a number of other proteins that affect actin dynamics. Some of these proteins have homology to proteins in animal cells that are believed to be involved in endocytosis. In addition, the demonstration that ubiquitination of some cell surface molecules is required for their efficient internalization is described. We compare the actin, myosin and ubiquitin requirements for endocytosis with recent results found studying these processes usingDictyostelium discoideum and animal cells.     

国产空间实用太阳电池抗质子辐射性能研究

研究了国产卫星用背场Ｓｉ太阳电池和ＧａＡｓ／Ｇｅ太阳电池性能随质子辐照注量１×１０９ －５ × １０１３ ｃｍ－２的变化．实验表明,２种太阳电池的电性能随辐照注量增加有不同的衰降趋势．背场 Ｓｉ太阳电池性能参数短路电流Ｉｓｃ和最大输出功率Ｐｍａｘ衰降变化快,辐照注量为２ × １０１０ｃｍ－２时, Ｐｍａｘ就已衰降为原值的７５％,而ＧａＡｓ／Ｇｅ太阳电池对应相同的衰降辐照注量达８×１０１１ｃｍ－２,且 Ｉｓｃ和Ｐｍａｘ衰降变化起初缓慢,当辐照注量接近３ × １０１２ ｃｍ－２时才迅速下降．背场Ｓｉ太阳电池性能 衰降与质子辐照引入的Ｅｖ＋０．１４ ｅＶ和Ｅｖ＋０．４３ ｅＶ深能级有关,而ＧａＡｓ／Ｇｅ太阳电池性能衰降 与辐照产生的Ｅｃ－０．４１ ｅＶ深能级有关．     

5～20MeV高能质子辐照对空间实用GaAs/Ge太阳电池性能的影响

用能量为5～20MeV,注量为1×109～7×1013cm-2的高能质子对空间实用GaAs/Ge太阳电池进行辐照,得到了其性能随质子能量和注量的变化关系,并对变化关系进行了能损模拟分析.结果表明:注量低于1×109cm-2的质子辐照不会引起太阳电池性能的变化;当注量增加为3×1012cm-2时,5,10,20MeV质子辐照引起的太阳电池性能参数Isc的衰降变化分别是原值的80%,86%,90%;Voc的衰降变化分别为原值的82%,85%,88%; Pmax的衰降变化分别为原值的60%,64%,67%.当辐照注量为5×1013cm-2时,5,10,20MeV质子辐照引起的Pmax衰降变化分别为原值的26%,30%,36%.即随着注量的增加,太阳电池性能衰降增大;且相同注量的辐照,质子能量愈高,太阳电池性能衰降愈小.     

电子辐照苎麻纤维引起结晶度和力学性能的变化

用BF-5直线加速器提供的电子束对苎麻纤维织物进行了0~500kGy范围不同剂量的辐照,使苎麻纤维的结晶度发生变化,采用X射线衍射仪(XRD)对辐照苎麻纤维的结晶度进行测试分析.并用材料万能试验机对辐照苎麻纤维织物的断裂强力、断裂伸长量等力学性能进行测试.研究表明:苎麻纤维的结晶度随辐照剂量增大而明显下降,苎麻纤维织物断裂强力、断裂伸长量均随辐照剂量增大而下降;苎麻纤维织物力学性能下降与电子束辐照降低了纤维结晶度有关.     

川芎多糖分离提取的工艺探究

将川芎(Ligusticum Chuanxiong Hort)的干燥根经常温粉碎,分别采用石油醚脱去脂溶性物质、根据多糖在95%溶液中不溶的性质,沉淀出粗多糖.粗多糖经无水乙醇、无水乙醚、丙酮脱水,真空干燥,碱法得到川芎多糖的粗多糖粉末.称重计算,粗多糖的收率为6.7%.     

An approach to improving the dynamical extended—range（monthly） prediction

Focusing on common and significant forecast errors-the zonal mean errors in the numerical prediction model,this report proposes an approach to improving the dynamical extended-range(monthly) prediction.Firstly,the monthly pentad-mean nonlinear dynamical regional predic-tion model of the zonal-mean haight based on a large number of historical data is constituted by employing the reconstruc-tion phase space theory and the spatio-temporal series pre-dictive method.The zonal height thus produced is trans-formed to its counterpart in the numerical model and fur-ther used to revise the numerical model prediction during the integration process.In this way,the two different kinds of prediction are combined.The forecasting experimenal results show that the above hybrid approach not only re-duces the systematical reeor of the numerical model,but also improves the forecast of the non-axisymmetric components due to the wave-flow interaction.     

Hierarchy and nonstationarity in climate systems： Exploring the prediction of complex systems

The prediction theories for complex systems with a hierarchial structure and their applications to the climate process are a significant and forward-looking field of research.However,up to the present,they are yet not known and understood very well. This paper presents a preliminary theoretical frame for them.As a normal example,the basic behaviors and the dynamic strructure of the climate system are discussed in detail.The conclusions indicate that the climate system may be considered as a cascade of several subsystems located in different hierarchies.Such a dynamic structure is just the cause resulting in the nonstationarity.The conclusions also indicate that the main barrier of the climate prediction in theory derives from the contrary between the stationarity hypothesis for the current prediction theory and the nonstationary behavior of the real climate process.In addition,some work is disussed for detecting the nonstationarity in climate and other geophysical data and predicting the nonstationary process developed in recent years.These works may construct a preliminary base for applying to the climate predictions.