街谷绿化消减机动车排放污染物的研究方法与进展

随着街道两侧建筑群向高密度、高层化发展,传统“树越多越好”的绿化模式在应对城市街谷空气污染时是否适用受到广泛关注。明晰街谷绿化植物特征及其种植设计模式对机动车排放污染物消减的调控机理是发挥其提升街谷空气品质的重要前提。本文通过对近年国内外相关文献的梳理,比较分析了现场观测、风洞试验和数值模拟3种研究方法的适用性及局限性,详细剖析了行道树、绿篱两类绿化模式对街谷空气污染物扩散与沉降的影响机制,提出了一套面向空气质量提升的街谷绿化适应性设计工作框架。最后,分别从典型街谷绿化设计图示语言研制、街谷空气污染暴露评估技术指南编制、计算机流体力学模型中街谷绿化效应物理过程参数化方案优化等方面进行探讨,以期为后续研究提供思路和借鉴。     

Alterations to plasma membrane lipid contents affect the biophysical properties of erythrocytes from individuals with hypertension

Genetic and environmental factors may contribute to high blood pressure, which is termed essential hypertension. Hypertension is a major independent risk factor for cardiovascular disease, stroke and renal failure; thus, elucidation of the etiopathology of hypertension merits further research. We recently reported that the platelets and neutrophils of patients with hypertension exhibit altered biophysical characteristics. In the present study, we assessed whether the major structural elements of erythrocyte plasma membranes are altered in individuals with hypertension. We compared the phospholipid (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, sphingosine) and cholesterol contents of erythrocytes from individuals with hypertension (HTN) and healthy individuals (HI) using LC/MS-MS. HTN erythrocytes contained higher phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine contents and a lower cholesterol content than HI erythrocytes. Furthermore, atomic force microscopy revealed important morphological changes in HTN erythrocytes, which reflected the increased membrane fragility and fluidity and higher levels of oxidative stress observed in HTN erythrocytes using spectrophotofluorometry, flow cytometry and spectrometry. This study reveals that alterations to the lipid contents of erythrocyte plasma membranes occur in hypertension, and these alterations in lipid composition result in morphological and physiological abnormalities that modify the dynamic properties of erythrocytes and contribute to the pathophysiology of hypertension.     

Carbon “quantum” dots for bioapplications

Carbon “quantum” dots or carbon dots (CDots) exploit and enhance the intrinsic photoexcited state properties and processes of small carbon nanoparticles via effective nanoparticle surface passivation by chemical functionalization with organic species. The optical properties and photoinduced redox characteristics of CDots are competitive to those of established conventional semiconductor quantum dots and also fullerenes and other carbon nanomaterials. Highlighted here are major advances in the exploration of CDots for their serving as high-performance yet nontoxic fluorescence probes for one- and multi-photon bioimaging in vitro and in vivo, and for their uniquely potent antimicrobial function to inactivate effectively and efficiently some of the toughest bacterial pathogens and viruses under visible/natural or ambient light conditions. Opportunities and challenges in the further development of the CDots platform and related technologies are discussed.     

基于低相干光干涉的眼睛光学生物参数测量研究

目的 眼睛的光学生物参数中的眼轴长度(AL)和角膜曲率半径(CR)可以作为预防和监测眼球近视的两个重要参数。为了提高测量眼轴长度的速度与精度和同步实现角膜曲率高精度动态测量,本文提出一种基于低相干光干涉技术眼睛光学生物参数测量的系统。方法 该系统使用旋转光学延迟线快速改变参考光的光程,利用曲率半径为8 mm的标准件标定人眼角膜顶点到靶环之间的距离,利用角膜的干涉信号对相机和数据采集卡进行触发实现同步采集,从而实现眼轴长度的快速测量和精准定位靶环到角膜顶点之间的距离,同时保证成像系统的放大倍率恒定和数据的实时采集。结果 实验结果表明,这种低相干光干涉测量系统,可以实时测量眼轴长度和角膜曲率半径,眼轴长度误差低于40μm,人眼角膜曲率半径方差为2.082 36×10^-2μm。结论 该系统能够快速、精准地测量AL和CR,可在近视的预防和监测中发挥重要作用。     

Molecular epidemiology of plasmid mediated resistance to fosfomycin among bacteria isolated from different environments

In this report we present data on the dispersion of a gene responsible for the plasmid-mediated resistance to fosfomycin among bacteria isolated from four hospitals and seven geographically separated domestic sewage treatment plants. Colony hybridization experiments, using a 0.85 kbp DNA fragment which carried the fosfomycin resistance determinant, have shown that the gene was present in isolates from three hospitals and six sewage plants although with different incidence and that it is carried by species of Enterobacteriaceae, Pseudomonas, Acinetobacter, Staphylococcus and Bacillus .     

Differential interactions of antitumor antibiotics chromomycin A(3) and mithramycin with d(TATGCATA)(2) in presence of Mg(2+)

The antitumor antibiotics chromomycin A(3) (CHR) and mithramycin (MTR) are known to inhibit macromolecular biosynthesis by reversibly binding to double stranded DNA with a GC base specificity via the minor groove in the presence of a divalent cation such as Mg(2+). Earlier reports from our laboratory showed that the antibiotics form two types of complexes with Mg(2+): complex I with 1:1 stoichiometry and complex II with 2:1 stoichiometry in terms of the antibiotic and Mg(2+). The binding potential of an octanucleotide, d(TATGCATA)(2), which contains one potential site of association with the above complexes of the two antibiotics, was examined using spectroscopic techniques such as absorption, fluorescence, and circular dichroism. We also evaluated thermodynamic parameters for the interaction. In spite of the presence of two structural moieties of the antibiotic in complex II, a major characteristic feature was the association of a single ligand molecule per molecule of octameric duplex in all cases. This indicated that the modes of association for the two types of complexes with the oligomeric DNA were different. The association was dependent on the nature of the antibiotics. Spectroscopic characterization along with analysis of binding and thermodynamic parameters showed that differences in the mode of recognition by complexes I and II of the antibiotics with polymeric DNA existed at the oligomeric level. Analysis of the thermodynamic parameters led us to propose a partial accommodation of the ligand in the groove without the displacement of bound water molecules and supported earlier results on the DNA structural transition from B --> A type geometry as an obligatory requirement for the accommodation of the bulkier complex II of the two drugs. The role of the carbohydrate moieties of the antibiotics in the DNA recognition process was indicated when we compared the DNA binding properties with the same type of Mg(2+) complex for the two antibiotics.     

Reflective properties of different eyespot types in dinoflagellates

The reflective properties of different types of dinoflagellate eyespots were investigated using confocal laser scanning microscopy in the epireflection contrast mode. Although the eyespots studied differed with respect to localization (cytosol or plastid) and organization of the globule layer(s), all types effectively absorbed and reflected blue-green laser light (principal lines of 488/514 nm). The relative orientation of the eyespot surface towards the light source strongly influenced the reflective properties. Maximal reflection occurred when the eyespot surface was approximately perpendicular to the light source and rapidly decreased at increasing angles of light incidence. Horizontal and vertical optical sectioning of live and fixed cells resolved differences in the reflection patterns. Focusing of reflected light on the basal portion of the longitudinal flagellum was observed for the cytosolic eyespot of Glenodinium sp. and the triple membrane-bounded eyespot of Peridinium foliaceum, presumably a vestige of a host plastid. This flagellum is thought to be mainly involved in mediating orientational movement responses. In contrast, the reflection patterns obtained from the eyespot of Woloszynskia pascheri, which represents the third and most commonly observed dinoflagellate eyespot type within a plastid, point to only minor focusing. Reflection signals could be followed a considerable distance into the sulcus in all cases, indicating that in dinoflagellate eyespots, irrespective of the presumed receptor location (plasma membrane overlying the eyespot and/or the basal part of the longitudinal flagellum), back reflection of non-absorbed light can enhance the excitation probability of the photoreceptor(s). Such a combined reflection/absorption screen allows maximal contrast modulation and will, in conjunction with the specialized geometry of the dinoflagellate eyespots, increase the directionality of these eyespot aparatuses considerably.     

Pollen dispersion, pollen viability and pistil receptivity in Leymus chinensis

BACKGROUND AND AIMS: Leymus chinensis is an economically and ecologically important grass that is widely distributed across eastern areas of the Eurasian steppe. A major problem facing its propagation by man is its low sexual reproductivity. The causes of low fecundity are uncertain, largely because many aspects of the reproductive biology of this species remained unknown or incomplete. This study aims to address some of these issues. METHODS: Pollen dispersion, pollen viability, pollen longevity and pistil receptivity were studied in a representative, natural population of L. chinensis growing in Inner Mongolia. KEY RESULTS: Flowering of L. chinensis occurred at the end of June and lasted for 5 d. Pollination peaked between 1600 h and 1700 h, and about 56.1 % of the total pollen grains were released at this time. Pollen density was highest towards the middle of flowering spikes and lowest at the bottom over the 5 d measurement period. Pollen viability (62.4 %) assessed using TTC was more accurate than using IKI (85.6 %); 50 % of pollen arriving on stigmas germinated. Pollen remained viable for only 3 h and the pollen : ovule ratio was 79 333 : 1. Pistil receptivity lasted for only 3 h and, overall, 86.7 % of pistils were pollinated. Within the spike, the relative fecundity of different positions was middle > lower > upper throughout the period of pollination; daily variation of fecundity was similar to that of the pollen flow. The spikes that opened on the day of highest pollen density exhibited the highest fecundity (36.0 %). No seeds were produced by self-pollination. CONCLUSIONS: The data suggest that low pollen viability, short pollen longevity and short pistil receptivity all appear to contribute to the low seed production typical of this important forage crop.     

Development of an optical immunosensor based on the fluorescence of Cyanine-5 for veterinarian diagnostics

A model optical immunosensor was developed to quantify an antibody present in a sample by measuring the fluorescence of Cyanine-5 conjugated with the antibody, using a competitive and a sandwich immunoreaction configuration, with the antigen immobilised in controlled pore glass beads. At pH 2, 94% of the antigen-antibody complex was dissociated, allowing reutilisation. Photobleaching had no effect on the fluorescence. This model system was used to detect Brucella sp. infection and could quantify anti-Brucella sp. antibodies in ovine serum samples in the range from 0.005 to 0.11 mg ml(-1).     

Hsp42 is the general small heat shock protein in the cytosol of Saccharomyces cerevisiae

Small heat shock proteins (sHsps) are ubiquitous molecular chaperones that prevent the unspecific aggregation of proteins. So far, Hsp26 was the only unambiguously identified member of the sHsp family in Saccharomyces cerevisiae. We show here that the sHsp system in the cytosol of S. cerevisiae consists of two proteins, Hsp26 and Hsp42. Hsp42 forms large dynamic oligomers with a barrel-like structure. In contrast to Hsp26, which functions predominantly at heat shock temperatures, Hsp42 is active as a chaperone under all conditions tested in vivo and in vitro. Under heat shock conditions, both Hsp42 and Hsp26 suppress the aggregation of one-third of the cytosolic proteins. This subset is about 90% overlapping for Hsp42 and Hsp26. The sHsp substrates belong to different biochemical pathways. This indicates a general protective function of sHsps for proteome stability in S. cerevisiae. Consistent with this observation, sHsp knockout strains show phenotypical defects. Taken together, our results define Hsp42 as an important player for protein homeostasis at physiological and under stress conditions.