全内反射荧光法的发展及其应用

全内反射荧光法是空间分辨荧光分析技术中重要的部分,该技术突破了传统荧光分析的局限,为获得空间定位信息提供了技术保障.该文系统地综述了全内反射荧光法的原理,特点,发展进程及其应用.引用文献37篇.     

Aerosol particles in the developing world; a comparison between New Delhi in India and Beijing in China

In developing countries, aerosol particles damage the health of hundreds of millions of people. Migration from the country side to megacities increases emissions and exposure to particles. Some countries have started to limit emissions based on particulate mass, but this may increase particle number concentrations. In this study we discuss some earlier measurements carried out in the developing world and compare results from one-week measurement campaigns concerning the particle number size distribution and PM₁₀ mass concentrations in New Delhi, India and Beijing, China. Our results show that submicron particle concentrations are high in both places. The average PM₁₀ concentration was 360 μg/m³ in New Delhi and 120 μg/m³ in Beijing. The corresponding total particle number concentrations in the size range 3–800 nm were 63 000 cm^?3 and 35 000 cm^?3. Number and mass concentrations and their characteristics showed significantly different behaviour between these two locations, which stresses the importance of long-term simultaneous measurements of both quantities in different types of megacities.     

猪场重要虫媒及其传播病原研究进展

近年来,非洲猪瘟、牛结节性皮肤病等外来可由虫媒传播的疫病肆虐中国,而一些已在国外流行的虫媒传播病原如非洲马瘟等传入中国的风险也越来越高,严重危害中国畜牧养殖业的发展和公共卫生安全。特别是2018年8月以来非洲猪瘟在中国的流行给养猪业带来重要警示信息,即防止猪场媒介生物进入并阻断其携带病原的传播将成为猪场生物安全的重点。蚊、蝇、蠓及蜱等是猪场和发病猪群传播疫病的重要虫媒因素,虫媒种类及从虫媒中分离到的病毒、细菌、寄生虫等病原种类繁杂,虫媒生物特性的差异对病原的传播方式和传播能力也不尽相同。鉴于此,作者详细归纳了猪场存在的主要虫媒种类及其传播的重要猪病病原,包括猪乙型脑炎病毒、猪繁殖与呼吸综合征病毒、非洲猪瘟病毒、盖塔病毒、猪肠道冠状病毒、大肠杆菌、猪链球菌等,并探讨其危害性和传播风险,以降低猪场虫媒传播疾病所带来的经济损失。     

Myosin I can act as a molecular force sensor

The ability to sense molecular tension is crucial for a wide array of cellular processes, including the detection of auditory stimuli, control of cell shape, and internalization and transport of membranes. We show that myosin I, a motor protein that has been implicated in powering key steps in these processes, dramatically alters its motile properties in response to tension. We measured the displacement generated by single myosin I molecules, and we determined the actin-attachment kinetics with varying tensions using an optical trap. The rate of myosin I detachment from actin decreases >75-fold under tension of 2 piconewtons or less, resulting in myosin I transitioning from a low (<0.2) to a high (>0.9) duty-ratio motor. This impressive tension sensitivity supports a role for myosin I as a molecular force sensor.     

嘉宝果风味低糖桃酥配方的优化

为研究嘉宝果风味低糖桃酥的制备工艺,按照国标对嘉宝果果渣粉的主要成分进行测定和分析,并以嘉宝果果渣粉、黄油、糖粉添加量和嘉宝果果渣粉目数为主要因素,以桃酥感官评分和质构评分为指标,采用L₉(3⁴)正交试验设计方案进行优化。研究得出桃酥的最优配方为低筋面粉100%,添加泡打粉1%,小苏打1%,全蛋液20%,100目嘉宝果果渣粉5%,黄油50%,糖粉9%,甜菊糖0.1%。在此配方下制得的桃酥感官评分89.91分,硬度为33.56N,黏附性为0.25 N/mm,弹性为0.49 mm,咀嚼性为0.81 mJ。     

Optimization of Quantitative Real-time PCR System on Amplification of Beta-glucosidase Gene Os1bglu4

[Objective] This study aimed to establish a quantitative real-time PCR(qRT-PCR) system for detecting the expression of rice beta-glucosidase gene Os1bglu4. [Method] The PCR was conducted with SYBR Green I method, using the primers of reference gene actin or ubiquitin. [Result] Actin was more suitable to be the reference gene than ubiquitin. More accurate results were obtained when the 100 ng cDNA template was added at a large volume and a lower concentration.The primer concentration in the range from 0.2 to 0.8 μmol/L we set had no significant influence on the results, so, 0.4 μmol/L was selected as the optimal primer concentration in this study. The amplification efficiency was greatly reduced when the annealing temperature was set at 64 ℃, therefore, annealing temperature was set at 60 ℃. Compared with the reaction system of 25 μl, the fluorescence intensity was significantly lower but the CT value did not change greatly in 10 μl system.So, the 10 μl reaction system was selected, which significantly reduces the research costs for the detection of a large amount of samples in future study.     

Sprouting of Populus tremula L. in spruce regeneration areas following alternative treatments

We investigated the efficiency of three different methods to restrict sprouting in European aspen (Populus tremula L.) in regeneration areas of spruce in Finland. The methods compared were (1) traditional method (cutting at 10?C15 cm height) (2) cutting at 1 m height, and (3) fungus treatment (cutting at 10?C15 cm height, and mycelium of a white-rot fungus, Chondrostereum purpureum [Pers. Ex Fr.] Pouzar was applied to freshly cut stumps). The results indicated that the fungus treatment can restrict the emergence and growth of stump sprouts better than other methods, whereas cutting at 1 m seemed to yield the lowest numbers of root suckers. However, differences between the treatments were not significantly different (P values were > 0.05). For future experimentation, we suggest that the cutting of higher stumps to control the number of root suckers should be combined with application of C. purpureum to restrict the emergence and growth of stump sprouts. We also suggest developing more efficient C. purpureum isolates to control European aspen stump sprouting.     

Microwave heating causes rapid degradation of antioxidants in polypropylene packaging, leading to greatly increased specific migration to food simulants as shown by ESI-MS and GC-MS

Microwave heating of commercial microwavable polypropylene packaging in contact with fatty food simulants caused significant antioxidant degradation and increased specific migration as shown by electrospray ionization-mass spectrometry (ESI-MS) and gas chromatography-mass spectrometry (GC-MS). Degradation of the antioxidants Irgafos 168 and Irganox 1010 was not detected during conventional heating of polypropylene packaging at the same temperature. The migration into aqueous food simulants was primarily restricted by the water solubility of the migrants. Using isooctane as fatty food simulant caused significant swelling and greatly enhanced overall migration values compared to the other fatty food simulant, 99.9% ethanol, or the aqueous food simulants 10% ethanol, 3% acetic acid, or water. ESI-MS spectra clearly reflected the overall migration values, and the number and amount of compounds detected decreased as the hydrophilicity of the food simulant increased. ESI-MS was shown to be an excellent tool for the analysis of semivolatile migrants and a good complement to GC-MS analysis of volatile migrants.     

Characterization of <Emphasis Type="Italic">Dickeya</Emphasis> strains isolated from potato and river water samples in Finland

Plant pathogenic enterobacteria in the genera Pectobacterium and Dickeya (formerly classified as Erwinia) were isolated from diseased potato stems and tubers. The isolated bacteria were identified as P. atrosepticum, P. carotovorum and pathogens in the genus Dickeya with PCR tests. Furthermore, Dickeya strains were isolated from river water samples throughout the country. Phylogenetic analysis with 16S-23S rDNA intergenic spacer sequences suggested that the Dickeya strains could be divided into three groups, two of which were isolated from potato samples. Phylogenetic analysis with 16S rDNA sequences and growth at 39°C suggested that one of the groups corresponds to D. dianthicola, a quarantine pathogen in greenhouse cultivation of ornamentals, while two of the groups did not clearly resemble any of the previously characterised Dickeya species. Field trials with the strains indicated that D. dianthicola-like strains isolated from river samples caused the highest incidence of rotting and necrosis of potato stems, but some of the Dickeya strains isolated from potato samples also caused symptoms. The results showed that although P. atrosepticum is still the major cause of blackleg in Finland, virulent Dickeya strains were commonly present in potato stocks and rivers. This is the first report suggesting that Dickeya, originally known as a pathogen in tropical and warm climates, may cause diseases in potato in northern Europe.     

Edge effects and trampling in boreal urban forest fragments – impacts on the soil microbial community

Fragmentation of forest ecosystems increases the proportion of edge habitat and is accompanied by a change in plant species composition. The recreational use of urban forests leads to decreased vegetation cover and the formation of paths, and thus, to fragmentation at small scales. We studied the impacts of forest and path edge effects on the soil microbial community structure (by using the phospholipid fatty acid (PLFA) method) and microbial activity (measured as basal respiration) in 34 mesic boreal urban forest fragments in Finland. We sampled the humus layer 1) from the forest edge into the interior (0–80 m), and 2) at different distances from paths. Microbial community structure was only slightly affected by the forest edge but differences were found between distances of 0–10 m and over 50 m from the edge. These changes correlated with changes in soil pH. Although changes in the microbial community structure were not pronounced, microbial biomass and activity were 30–45% lower at the first 20 m into the forest fragments, due to a low moisture content of the humus near the edge. The decreased microbial activity detected at forest edges implies decreased litter decomposition rates, and thus, a change in ecosystem nutrient cycling. The microbial community structure differed between paths and surrounding areas and correlated with changes in soil pH. Paths also supported approximately 25–30% higher microbial biomass with a transition zone of at least 1 m from the path edge. Path associated disturbances (mainly alterations in vegetation and soil pH) were reflected in the soil microbial community structure up to 1.5 m from the paths.