儿科产超广谱β-内酰胺酶肺炎克雷伯菌感染现状及耐药性分析

目的研究吉林市2005年1月至2007年12月期间儿科产超广谱β－内酰胺酶（extended speetrurn β－lactamases,ESBLs）肺炎克雷伯菌感染现状及耐药性。方法按照CLSI／NCCLS2005年标准筛选确认ESBLs表型,采用琼脂纸片扩散法进行药敏试验。结果ESBLs总检出率为56．3％,3年检出率分别为2005年33．3％、2006年47．1％和2007年为57．1％。产ESBLs菌株全部表现为多重耐药,对氨苄西林、哌拉西林、头孢呋辛和头孢唑啉的耐药率达100％,对阿米卡星、头孢吡肟、头孢他啶和哌拉西林／他唑巴坦的耐药率低于50％,对头孢噻肟、头孢曲松和氨曲南的耐药率逐年上升,发现对亚胺培南耐药菌株。结论吉林市儿科产ESBLs肺炎克雷伯菌检出率较高,临床治疗中应重视产ESBLs菌的监测,并动态监测其耐药性变迁,防止ESBLs肺炎克雷伯菌的传播。     

胶毒素与BSA的相互作用

应用荧光、圆二色和紫外—可见吸收等波谱法研究胶毒素与牛血清白蛋白(BSA)的相互作用。荧光光谱实验结果表明胶毒素主要靠疏水作用与BSA结合, 而对其内源荧光产生猝灭作用,其淬灭方式为静态猝灭, 胶毒素与BSA的结合常数为7.2×103 L/mol。圆二色光谱检测发现, 随着胶毒素浓度的增加, BSA的a-螺旋数量也增加, 当胶毒素浓度为BSA浓度的100倍时, BSA的a-螺旋增加40.1%, 表明胶毒素与BSA的结合改变了BSA的空间构象。     

Estimation of Cellobiohydrolase I Activity by Numerical Differentiation of Dynamic Ultraviolet Spectroscopy

1,4-β-D-glucan cellobiohydrolase I (CBH I),p-nitrophenyl β-D-cellobioside,p-nitrophenol andcellobiose show distinct ultraviolet spectra,allowing the design of an assay to track the dynamic process ofp-nitrophenyl β-D-cellobioside hydrolysis by CBH I.Based on the linear relationship between p-nitrophenolformation in the hydrolysate and its first derivative absorption Curve of AUC340_400_(nm)(area under the curve),a new sensitive assay for the determination of CBH I activity was developed.The dynamic parameters ofcatalysis reaction,such as Vm and k_(cat),can all be derived from this result.The influence of β-glucosidase andendoglucanase in crude enzyme sample on the assay was discussed in detail.This approach is useful foraccurate determination of the activity of CBHs.     

大蒜产香内生真菌的分离及其挥发性成分分析

大蒜(Allium sativum L.)是百合科葱属常见的植物,富含丰富的生物活性成分和营养物质。本研究采用组织分离法从新鲜的大蒜中分离内生真菌并进行纯化,获得1株产香浓郁的菌株KLBMPAS015。采用固相微萃取固定吸附,结合气相色谱-质谱解吸附分析技术(SPME-GC-MS)对菌株KLBMPAS015的挥发成分进行分析。结果表明:该菌株代谢产物的香气成分主要为:n-丁酸2-乙基己基酯(n-butyric acid 2-ethylhexyl ester)(1.36%)、1-丁醇3-甲基-丙酸(1-butanol,3-methyl-,propanoate)(25.40%)和戊基惕各酸(iso-amyl tiglate)(65.51%)。产香真菌KLBMPAS015的戊基惕各酸含量相对较高,在天然香料生产中具有重要的潜在应用价值。     

Study of the Antifungal Ability of Bacillus subtilis Strain PY-1 in Vitro and Identification of its Antifungal Substance （Iturin A）

A Bacillus strain,denoted as PY-1,was isolated from the vascular bundle of cotton.Biochemical,physiological and 16S rDNA sequence analysis proved that it should belong to Bacillus subtilis.The PY-1strain showed strong ability against many common plant fungal pathogens in vitro.The antibiotics producedby this strain were stable in neutral and basic conditions,and not sensitive to high temperature.From theculture broth of PY-1 strain,five antifungal compounds were isolated by acidic precipitation,methanolextraction,gel filtration and reverse-phase HPLC.Advanced identification was performed by mass spec-trometry and nuclear magnetic resonance spectroscopy.These five antifungal compounds were proved to bethe isomers of iturin A:A2,A3,A4,A6 and A7.In fast atom bombardment mass spectrometry/mass spec-trometry collision-induced dissociation spectra,fragmentation ions from two prior linear acylium ions wereobserved,and the prior ion,Tyr-Asn-Gln-Pro-Asn-Ser-βAA-Asn-CO~ ,was first reported.     

紫球藻藻红蛋白的分离纯化及光谱学特性

采用4℃反复浸提、离心、硫酸铵沉淀、DEAE—Sepharose Fast Flow离子交换柱层析,从紫球藻（Porphyridium cruentum Naegeli）冻干粉中分离纯化藻红蛋白,分离纯度达到4．85,总收率51．9％;经羟基磷灰石柱层析纯化,藻红蛋白纯度达到5．10,总收率34．0％,聚丙烯酰胺凝胶电泳显示1条带。所分离纯化的藻红蛋白含有3个亚基（α、β、γ）,在可见光区545nm和560nm处有2个吸收峰,在498nm处有1个吸收肩峰。实验结果说明所分离纯化的藻红蛋白纯度符合要求。     

Biological implications of genetic variations in autism spectrum disorders from genomics studies

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental condition characterized by atypical social interaction and communication together with repetitive behaviors and restricted interests. The prevalence of ASD has been increased these years. Compelling evidence has shown that genetic factors contribute largely to the development of ASD. However, knowledge about its genetic etiology and pathogenesis is limited. Broad applications of genomics studies have revealed the importance of gene mutations at protein-coding regions as well as the interrupted non-coding regions in the development of ASD. In this review, we summarize the current evidence for the known molecular genetic basis and possible pathological mechanisms as well as the risk genes and loci of ASD. Functional studies for the underlying mechanisms are also implicated. The understanding of the genetics and genomics of ASD is important for the genetic diagnosis and intervention for this condition.     

七姊妹山自然保护区黄杉林群落学特征

黄杉为国家Ⅱ级保护植物,是我国特有的第三纪孑遗的珍贵树种,主要分布在我国亚热带的中山地带。采用Braun-Blanquet的植物社会学调查方法并结合典型样方法对七姊妹山自然保护区的原生黄杉群落进行调查,并对其群落特征进行了分析。结果表明:在2300 m~2的调查样地,共有维管束植物52种,隶属24科38属,群落物种组成主要以杜鹃花科、豆科、五加科、壳斗科等种类为主;群落生活型组成分析显示,该黄杉群落高位芽植物占绝对优势,高位芽植物、地面芽植物占比分别为76.9%、13.5%,地上芽和地下芽植物较少,植物的生活型谱大致呈"L"型;群落重要值分析表明,黄杉重要值为53.6,占较大优势,是群落建群种,乌冈栎、石韦分别是灌木层及草本层的优势种,其重要值分别为24.0、54.8;该黄杉群落物种多样性指数整体较低,除均匀度指数外,优势度指数、多样性指数、丰富度指数总体表现出灌木层乔木层草本层,上坡山脊的规律;种群年龄结构分析表明,七姊妹山自然保护区黄杉种群年龄结构呈"L"型分布,属于增长型种群,在一定时间内,表明黄杉仍为该群落的优势种群,林窗的出现使该黄杉群落保持持续更新。     

Variations of leaf longevity in tropical moist forests predicted by a trait‐driven carbon optimality model

Leaf longevity (LL) varies more than 20‐fold in tropical evergreen forests, but it remains unclear how to capture these variations using predictive models. Current theories of LL that are based on carbon optimisation principles are challenging to quantitatively assess because of uncertainty across species in the ‘ageing rate:’ the rate at which leaf photosynthetic capacity declines with age. Here, we present a meta‐analysis of 49 species across temperate and tropical biomes, demonstrating that the ageing rate of photosynthetic capacity is positively correlated with the mass‐based carboxylation rate of mature leaves. We assess an improved trait‐driven carbon optimality model with in situLL data for 105 species in two Panamanian forests. We show that our model explains over 40% of the cross‐species variation in LL under contrasting light environment. Collectively, our results reveal how variation in LL emerges from carbon optimisation constrained by both leaf structural traits and abiotic environment.     

Air and surface soil samples – two different pairs of shoes? Comparing the pollen spectrum on different days of the pollen season

The pollen spectra of air and surface soil samples from a rooftop (at 14 m) and from ground level (at 1.6 m) in the suburbs of Vienna (Austria) were compared. Two soil samples and two air samples were taken on four different days to account for possible differences: in winter when no pollination occurred (reference day), in spring during the main flowering of Betula (birch day), in spring/summer during the main flowering of Poaceae (grass day), and in autumn during the main flowering of Ambrosia (ragweed day). Thirty-five different pollen types were used to describe the pollen spectra. Frequencies of certain pollen types reflect a seasonal impact on both the surface soil and air samples and show a similarity between air and soil samples on most of the days. However, the seasonal impact is higher in the air samples and shows a high consistency for ground and rooftop level. Kendall’s tau correlation coefficients further substantiate the similarities of the samples especially for the pollen season days. Exceptions include the winter day when pollination was low and the air samples recorded nearly no pollen at all, and the ragweed day when Ambrosia pollen was abundant in three of four samples but not in the ground surface soil sample. Thus, (1) air and surface pollen samples record similar signals during the pollen season but not during the ragweed and winter season and (2) air and surface pollen samples show the impact of local vegetation also in pollen traps located at different heights.