Degradation of outer membrane proteins of <Emphasis Type="Italic">Synechococcus</Emphasis> sp. <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in situ</Emphasis>     

Tatsuo?Miyoshi  Satoru?SuzukiEmail author 《Journal of Oceanography》2004,60(5):825-833

To examine the possibility that outer membrane proteins (OMP) of Synechococcus sp. remain in seawater, we investigated the stability of OMPs in vitro and in situ. Some fractions prepared from Synechococcus sp. CSIRO-94 were treated with trypsin and proteinase K. Four tightly bound OMPs were separated from Synechococcus. We designated the two major OMPs of 52 kDa and 48 kDa as Omp52Sy and Omp48Sy, respectively. Degradation of the OMP in natural seawater was monitored in microcosms to which intact Synechococcus cells and outer membrane (OM) were added. Omp52Sy and Omp48Sy were the most stable against trypsin and proteinase K among the OMPs when they were embedded in the OM. However, in the microcosm experiment using intact cells, Omp52Sy and Omp48Sy were detected in the particulate fraction only during the first 4 days, after which they could not longer be detected. Omp52Sy and Omp48Sy were the most stable proteins among the Synechococcus OMPs in vitro, but they might be degraded in situ. This indicates that stability of Synechococcus porin differs depending on complex formation with other membrane molecules, which might cause different preservation of microbial membrane proteins in the dissolved protein pool in the ocean. This study suggests that Gram negative bacterial OM with thin peptidoglycan forms a lipid bilayer that proptects OMP, but Synechococcus OM with thick peptidoglycan cannot form a lipid bilayer. The incomplete bilayer might not be able to protect from protease attack in the natural environment.  相似文献   

致病性鳗弧菌W-1外膜蛋白ompU基因克隆及在大肠杆菌中的表达   总被引：1，自引：1，他引：1  

杨慧  陈吉祥  公衍军  李彩风  李筠  杨官品 《中国海洋大学学报(自然科学版)》2006,36(Z1):105-108

从致病性鳗弧菌W-1基因组DNA扩增并克隆了1 156bp的特异性片段,含有完整的外膜蛋白ompU基因阅读框,由993个核苷酸组成,编码330个氨基酸残基的蛋白质。与国外已发表的鳗弧菌外膜蛋白基因的序列同源性为100%,与创伤弧菌(Vibrio vulnificus)、霍乱弧菌(Vibrio cholerae)、费氏弧菌(Vibrio fischeri)和副溶血弧菌(Vibrio parahaemolyticus)的序列同源性分别为72%,69%,68%和64%。将该外膜蛋白基因克隆于pBV220表达质粒,在大肠杆菌中得到了表达,SDS-PAGE分析表明表达蛋白分子量约38kDa,Western blot分析发现表达蛋白能与鳗弧菌外膜蛋白抗体很好的反应。  相似文献   

Benthic fluxes of nitrogen in the tidal reaches of a turbid, high-nitrate sub-tropical river     

Perran L. M. Cook  Bradley D. Eyre  Rhys Leeming  Edward C. V. Butler   《Estuarine, Coastal and Shelf Science》2004,59(4):675-685

Benthic fluxes of dissolved inorganic nitrogen (NO₃⁻ and NH₄⁺), dissolved organic nitrogen (DON), N₂ (denitrification), O₂ and TCO₂ were measured in the tidal reaches of the Bremer River, south east Queensland, Australia. Measurements were made at three sites during summer and winter. Fluxes of NO₃⁻ were generally directed into the sediments at rates of up to −225 μmol N m⁻² h⁻¹. NH₄⁺ was mostly taken up by the sediments at rates of up to −52 μmol N m⁻² h⁻¹, its ultimate fate probably being denitrification. DON fluxes were not significant during winter. During summer, fluxes of DON were observed both into (−105 μmol m⁻² h⁻¹) and out of (39 μmol m⁻² h⁻¹) the sediments. Average N₂ fluxes at all sampling sites were similar during summer (162 μmol N m⁻² h⁻¹) and winter (153 μmol N m⁻² h⁻¹). Denitrification was fed both by nitrification within the sediment and NO₃⁻ from the water column. Sediment respiration rates played an important role in the dynamics of nitrification and denitrification. NO₃⁻ fluxes were significantly related to TCO₂ fluxes (p<0.01), with a release of NO₃⁻ from the sediment only occurring at respiration rates below 1000 μmol C m⁻² h⁻¹. Rates of denitrification increased with respiration up to TCO₂ fluxes of 1000 μmol C m⁻² h⁻¹. At sediment respiration rates above 1000 μmol C m⁻² h⁻¹, denitrification rates increased less rapidly with respiration in winter and declined during summer. On a monthly basis denitrification removed about 9% of the total nitrogen and 16% of NO₃⁻ entering the Bremer River system from known point sources. This is a similar magnitude to that estimated in other tidal river systems and estuaries receiving similar nitrogen loads. During flood events the amount of NO₃⁻ denitrified dropped to about 6% of the total river NO₃⁻ load.  相似文献   

Videogrammetric monitoring of as-built membrane roof structures     

Shih-Yuan  Lin  Jon P.  Mills  Peter D.  Gosling 《The Photogrammetric Record》2008,23(122):128-147

A monitoring system that uses applied geomatics techniques, including videogrammetry and terrestrial laser scanning, has been developed in order to investigate the dynamic behaviour of as-built membrane roof structures. To accommodate the problems involved in measuring such roof structures, examples of which include uniform surface texture and unreachable height, the system adopts a non-contact targeting methodology to substitute for traditional control techniques. In-house software was developed for processing the acquired video imagery in order to produce a sequential surface model of the membrane. This paper firstly reports on experiments conducted to demonstrate that the monitoring system was capable of measuring representative test structures with a precision of better than ±1 mm. To prove the feasibility and transferability of the system, videogrammetric monitoring campaigns were subsequently performed at a real-world test site where two different types of membrane structure were observed. The sequential 3D surface models that were generated allowed the displacement of the membrane surfaces to be investigated over a period, during which the range of the movement reached over 20 mm. The information acquired from the system is proving to be of great value to structural engineers involved in research and development of such membrane structures.  相似文献   

Modelling of membranes in the material point method with applications          下载免费PDF全文

Fursan Hamad  Dieter Stolle  Pieter Vermeer 《国际地质力学数值与分析法杂志》2015,39(8):833-853

The objective of this paper is to formulate and validate an accurate MPM approach for the numerical simulation of the large displacement of membranes containing soil. In the proposed approach, the membrane is discretised by a surface mesh that allows accurate simulation of membrane stresses. The membrane is free to move through a three‐dimensional grid for a continuum consisting of tetrahedral elements. The approach is applied to model a geocontainer being released from a split barge, taking into account the frictional contact between the geotextile and the barge. No‐slip contact is assumed between the geotextile and the soil inside. The effect of geocontainer interaction is investigated by dropping a second container. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

防渗膜渗漏偶极子检测的应用     

杨萍  孔波  姜余祥  王燕妮 《物探与化探》2014,(6)

偶极子法可用于防渗膜渗漏检测。膜上介质厚度以及偶极子与膜的距离会对偶极子检测的灵敏度产生影响。基于填埋场防渗膜高压直流电法的检测原理,对膜上介质厚度对偶极子检测的影响进行了研究,结果表明:防渗膜上介质厚度增大,通过在介质表面上移动偶极子来检测漏洞是困难的;但若偶极子能逼近膜的表面进行检测,无论膜上介质厚度多大,在漏洞附近都能检测到明显的电势异常。  相似文献   

边界问题及其对真空预压的影响     

高志义  冯军 《岩土工程技术》2014,28(5):250-256

给出了真空预压区四周开敞式与封闭式边界定义、两者的不同,分析了开敞式边界加固效果优于封闭式边界的原因并以三个实例说明之,给出如何将封闭式转化为开敞式的方法;柔性与刚性密封膜同样可构成开敞式与封闭式边界,讨论了此时两种边界下差别;给出了密封墙和支挡墙的定义、功能、应用范围;讨论了水泥搅拌与旋喷桩单体墙与格栅墙的定义、功能、应用范围,前者只能作为密封墙,后者既可作密封墙也可作支挡墙.  相似文献   

海洋沉积物中现存微生物化学标志物完整极性膜脂研究进展   总被引：3，自引：0，他引：3  

姚鹏  于志刚 《地球科学进展》2010,25(5):474-483

完整极性膜脂作为活的微生物细胞的化学标志物,能够反映海洋沉积物中现存微生物群落结构和生物量等信息.与生物学方法相比,完整极性膜脂分析技术具有无需培养、快速和普适性等特点.综述了海洋沉积物中细菌和古菌的细胞膜完整极性膜脂的组成特点及其在生物地球化学和微生物生态学等研究中的应用,重点评述了在生物地球化学循环中有特殊作用的微生物,如厌氧氨氧化细菌、甲烷氧化古菌、氨氧化古菌、具有四醚膜脂结构的海洋泉古菌等,或者是一些特殊生态系统,如冷泉、海底深部生物圈等研究中完整极性膜脂应用的进展.还简要介绍了完整极性膜脂的分析方法,并对其应用前景进行了展望.  相似文献   

IMPROVEMENT OF SANDY SOIL WITH WATERCONSERVING MEMBRANE AND ITS EFFECT ON CROP GROWTH   总被引：1，自引：0，他引：1  

LIXiu-jun CUIXiang-hao LIQu-sheng 《中国地理科学(英文版)》2005,15(1):64-69

1INTRODUCTIONArid, semi-arid, and semi-humid areas abound in sandysoil, which causes water to leak into deep soil orgroundwater so that soil′s water-conserving capabilitybecomes lower and water is used with low efficiency.Water is one of the important fa…  相似文献   

缘于任意自旋场的Vaidya黑洞的熵(英文)     

SHEN Yougen GAO Changjun 《中国科学院上海天文台年刊》2003,(1)

用在brick模型基础上发展起来的membrane模型 ,计算了缘于任意自旋场的非静态黑洞———Vaidya黑洞的自由能和熵。结果表明 ,玻色子场 (自旋s =1,2 )和费米子场 (自旋s =1/2 )的熵都恰好与黑洞的视界面积成正比 ,这与静态和稳态的情况相同。而且 ,玻色子和费米子场的熵具有相同的形式 ,二者相差一个系数  相似文献