Elevated microbial tolerance to metals and antibiotics in metal-contaminated industrial environments

To test the hypothesis that industrial metal contaminants select for microorganisms tolerant to unrelated agents, such as antibiotics, we analyzed metal and antibiotic tolerance patterns in microbial communities in the intake and discharge of ash settling basins (ASBs) of three coal-fired power plants. High-throughput flow-cytometric analyses using cell viability probes were employed to determine tolerances of entire bacterioplankton communities, avoiding bias toward culturable versus nonculturable bacteria. We found that bacterioplankton collected in ASB discharges were significantly more tolerant to metal and antibiotic exposures than bacterioplankton collected in ASB intakes. Optical properties of microorganisms collected in ASB discharges indicated no defensive physiological adaptations such as formation of resting stages or excessive production of exopolymers. Thus, it is likely that the elevated frequency of metal and antibiotic tolerances in bacterioplankton in ASB discharges were caused by shifts in microbial community composition, resulting from the selective pressure imposed by elevated metal concentrations or organic toxicants present in ASBs.     

Intercalating dye as an acceptor in quantum-dot-mediated FRET

Fluorescence resonance energy transfer (FRET) is a popular tool to study intermolecular distances and characterize structural or conformational changes of biological macromolecules. We investigate a novel inorganic/organic FRET pair with quantum dots (QDs) as donors and DNA intercalating dyes, BOBO-3, as acceptors by using DNA as a linker. Typically, FRET efficiency increases with the number of stained DNA linked to a QD. However, with the use of intercalating dyes, we demonstrate that FRET efficiency at a fixed DNA:QD ratio can be further enhanced by increasing the number of dyes stained to a DNA strand through the use of an increased staining dye/bp ratio. We exploit this flexibility in the staining ratio to maintain a high FRET efficiency of >0.90 despite a sixfold decrease in DNA concentration. Having characterized this new QD-mediated FRET system, we test this system in a cellular environment using nanocomplexes generated by encapsulating DNA with commercial non-viral gene carriers. Using this novel FRET pair, we are able to monitor the configuration changes and fate of the DNA nanocomplexes during intracellular delivery, thereby providing an insight into the mechanistic study of gene delivery.     

Verification of antiparallel G-quadruplex structure in human telomeres by using two-photon excitation fluorescence lifetime imaging microscopy of the 3,6-Bis(1-methyl-4-vinylpyridinium)carbazole diiodide molecule

Different G-quadruplex structures for the human telomeric sequence d(T2AG3)4 in vitro have been documented in the presence of sodium and potassium. Verification of the G-quadruplex structures in human telomeres in vivo is the main issue in establishing the biological function of the G-quadruplex structures in telomeres as well as the development of anticancer agents. Here we have applied two-photon excitation fluorescence lifetime imaging microscopy to measure the fluorescence lifetime of the BMVC molecule upon interaction with various DNA structures. The distinction in lifetime measured with submicrometer spatial resolution in two-photon excitation fluorescence lifetime imaging microscopy provides a powerful approach not only to verify the existence of the antiparallel G-quadruplex structure in human telomeres but also to map its localizations in metaphase chromosomes.     

全国安全防范报警系统标委会(TC100)1999年工作要点

一、解放思想、转变观念，继续探索标委会工作改革的新路子１在坚持“三个面向与服务”方针的基础上，进一步强化市场意识，试行“以市场需求为导向，努力为行业、为企业、为用户服务”的标准化工作模式，提高标准的适应性和有效性。２改革现行的“标准计划模式”，做...     

在加利福尼亚死亡裂谷,漫流与碎屑流进程对两个相邻冲积扇控 …

加利福尼亚死亡裂谷Ｐａｎａｍｉｎｔ山前地带两个型相邻的冲积扇由受到不同沉积作用而沉积的不同岩相组合而构成。Ａｎｖｉｌ Ｓｐｒｉｎｇ扇完全由水流程序（切蚀河道流和漫流）所建造，而相邻的ＷａｒｍＳｐｒｉｎｇ扇则主要由碎屑流形成。两个扇之间的边界形成了一个明显的山麓界面，朝南则以漫流形成的扇为主，朝北则为碎屑流形成的扇。对这两个扇而言，诸如气候、补给区扇面积、流域地形、平面形状、植被类型和密和密度及新构