Incorporation of β‐amino acids into ascidiacyclamides: Effects on conformation,cytotoxicity and interaction with copper (II) ion

Seven ascidiacyclamide [cyclo(–Ile–oxazoline–d ‐Val–thiazole–)₂] (ASC) analogues incorporating the β‐amino acids βIle, βoxazoline, and/or d ‐βVal were synthesized. We then investigated the effects of the position and number of incorporated β‐amino acids on the structure, cytotoxicity, and copper binding by these seven analogues. The structural analyses revealed that both βIle and d ‐βVal favor a gauche‐type θ torsion angles, while βoxazoline favors a trans‐type θ torsion angle. Expansion of the macrocycle by incorporation of βIle or d ‐βVal readily induced molecular folding. On the other hand, the incorporation of two βoxazoline residues strongly extended the peptide conformation, and the incorporation of one was sufficient for the moderate restriction important for conformational equilibrium and cytotoxicity. Despite expansion of the macrocycles, the structure‐cytotoxicity relationships were largely maintained. In studies of complexation of the analogues with Cu (II) ion, the position and number of incorporated β‐amino acids had a large impact on the structure of the metal complex and may contribute to its stabilization.     

正常小鼠高频心电图时域值和功率谱的研究

本文用南京新博公司生产的ＮＨＥ－１０００型心电高频信息检测分析仪研究了正常小鼠（昆明种）高频心电图（ＨＦ－ＥＣＧ）的时域值和ＱＲＳ波群的功率谱。主要结果如下（以正导为例,－Ｘ±ＳＤ）：心率６０３±８８次／ｍｉｎ（ｎ＝７４）;Ｐ－Ｒ间期相对较长。为３４．９±４．７ｍｓ（ｎ＝５８）,占心动周期的３４．９±４．９％,这与人类有很大的不同;ＱＲＳ波宽９．２±１．２ｍｓ,占心动周期的９．２±１．４％（ｎ＝７４）,这一结果与以前的文献报道相差较大。Ｔ波宽１０．３±３．２ｍｓ,占心动周期的１０．３±３．２％;Ｑ－Ｔ间期１９．４±３．２ｍｓ,占心动周期的１９．５±３．６％;ＱＲＳ波群峰－峰值（Ｖｐ－ｐ）为１．４５６±０．４８０ｍＶ;Ｔ波高０．３３６±０．１１５ｍＶ;７３只动物Ⅱ导联高频切迹总数只有３个,扭挫２６个。Ⅱ导联ＱＲＳ波群的功率谱特点：０—８０Ｈｚ的相对能量为４５．４８±１５．３２％;８０—２００Ｈｚ为４３．９７±９．９５％;２００—３００Ｈｚ为８．８９±７．３８％;３００—１０００Ｈｚ为１．６６±２．７４％。     

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。     

Nanosecond dynamics of a mimicked membrane-water interface observed by time-resolved stokes shift of LAURDAN

We studied the dipolar relaxation of the surfactant-water interface in reverse micelles of AOT-water in isooctane in the nanosecond and subnanosecond time ranges by incorporating the amphipathic solvatochromic fluorescent probes LAURDAN and TOE. A negative component was observed in the fluorescence decays in the red edge of the emission spectrum-the signature of an excited state reaction-with LAURDAN but not for TOE. The deconvolution of the transient reconstructed spectra of LAURDAN based on a model constructed by adding together three log-normal Gaussian equations made it possible to separate the specific dynamic solvent response from the intramolecular excited state reactions of the probe. The deconvoluted spectrum of lowest energy displayed the largest Stokes shift. This spectral shift was described by unimodal kinetics on the nanosecond timescale, whereas the relaxation kinetics of water-soluble probes have been reported to be biphasic (on the subnanosecond and nanosecond timescales) due to the heterogeneous distribution of these probes in the water pool. Most of this spectral shift probably resulted from water relaxation as it was highly sensitive to the water to surfactant molar ratio (w(0)) (60-65 nm at w(0) = 20-30). A small part of this spectral shift (9 nm at w(0) = 0) probably resulted from dipolar interaction with the AOT polar headgroup. The measured relaxation time values were in the range of the rotational motion of the AOT polar headgroup region as assessed by LAURDAN and TOE fluorescence anisotropy decays.     

Body-size spectra of biofilm-dwelling protozoa and their seasonal shift in coastal ecosystems

Community-based assessment of protozoa is usually performed at a taxon-dependent resolution. As an inherent ‘taxon-free’ trait, however, body-size spectrum has proved to be a highly informative indicator to summarize the functional structure of a community in both community research and monitoring programs in aquatic ecosystems. To demonstrate the relationships between the taxon-free resolution of protozoan communities and water conditions, the body-size spectra of biofilm-dwelling protozoa and their seasonal shift and environmental drivers were explored based on an annual dataset collected monthly from coastal waters of the Yellow Sea, northern China. Body sizes were calculated in equivalent spherical diameter (ESD). Among a total of 8 body-size ranks, S2 (19–27 μm), S3 (28–36 μm), S4 (37–50 μm) and S5 (53–71 μm) were the top four levels in frequency of occurrence, while rank S1 (13–17 μm), S2 and S4 were the dominant levels in abundance. These dominants showed a clear seasonal succession: S2/S4 (spring) → S2/S4 (summer) → S4 (autumn) → S2 (winter) in frequency of occurrence; S1 (spring) → S4 (summer) → S2 (autumn) → S1 (winter) in abundance. Bootstrapped average analysis showed a clear seasonal shift in body-size spectra of the protozoa during a 1-year cycle, and the best-matching analysis demonstrated that the temporal variations in frequency of occurrence and abundance were significantly correlated with water temperature, pH, dissolved oxygen (DO), alone or in combination with chemical oxygen demand (COD) and nutrients. Thus, the body-size spectra of biofilm-dwelling protozoa were seasonally shaped and might be used as a time and cost efficient bioindicator of water quality in marine ecosystems.     

Mechanical stability of trees under dynamic loads

Tree stability in windstorms and tree failure are important issues in urban areas where there can be risks of damage to people and property and in forests where wind damage causes economic loss. Current methods of managing trees, including pruning and assessment of mechanical strength, are mainly based on visual assessment or the experience of people such as trained arborists. Only limited data are available to assess tree strength and stability in winds, and most recent methods have used a static approach to estimate loads. Recent research on the measurement of dynamic wind loads and the effect on tree stability is giving a better understanding of how different trees cope with winds. Dynamic loads have been measured on trees with different canopy shapes and branch structures including a palm (Washingtonia robusta), a slender Italian cypress (Cupressus sempervirens) and trees with many branches and broad canopies including hoop pine (Araucaria cunninghamii) and two species of eucalypt (Eucalyptus grandis, E. teretecornus). Results indicate that sway is not a harmonic, but is very complex due to the dynamic interaction of branches. A new dynamic model of a tree is described, incorporating the dynamic structural properties of the trunk and branches. The branch mass contributes a dynamic damping, termed mass damping, which acts to reduce dangerous harmonic sway motion of the trunk and so minimizes loads and increases the mechanical stability of the tree. The results from 12 months of monitoring sway motion and wind loading forces are presented and discussed.     

致细菌性肝脓肿的肺炎克雷伯杆菌多位点序列分型及药敏分析

目的了解致细菌性肝脓肿的肺炎克雷伯杆菌多位点序列分型及药敏情况。方法收集2011年1月至2012年6月在浙江大学医学院附属第一医院感染科住院的细菌性肝脓肿患者,脓液培养为肺炎克雷伯杆菌的23株菌株,对23株菌株进行多位点序列分型;应用K—B纸片扩散法检测23株肺炎克雷伯杆菌菌株对10种抗菌药物的敏感性;应用超广谱β-内酰胺酶（ESBLs）确认试验了解23株菌株的产ESBLs情况。结果23株菌株经过多位点序列分型：ST23为最主要序列型,共有10株,ST25、ST30、ST65、ST86、ST163、ST367、ST375、ST380、ST660、ST700及ST806各1株,2株为新的ST型,未发现文献报道的产耐碳氢酶烯酶的常见sT型;23株菌株的药敏结果对哌拉西林他唑巴坦及头孢哌酮舒巴坦等8种抗菌药物的耐药率为0％,对头孢呋辛耐药率4．4％,而对氨苄西林的耐药率为100％;ESBLs确认试验其中22株为ESBL^-;1株为ESBL^＋。结论收治的致细菌性肝脓肿的肺炎克雷伯杆菌均为敏感菌株,可以经验性的选用青霉素（三代头孢）复合制剂,避免碳氢酶烯类抗生素的乱用及滥用。     

激光照射胚泡对家兔和小鼠的抗早孕研究

本文在家兔、小鼠上探索了激光的抗旱孕效应,观察到血卟啉衍生物(HPD)和激光的光化效应能使早期胚泡完全坏死和吸收,无流血和晚期流产现象,通过PNQ_3荧光分光光度计测定HPD在胚胎组织中的荧光谱,证实HPD对胚胎组织有亲和力,其对滋养叶细胞比对宫壁组织的亲和力大4倍,借以解释激光光化效应抗早孕的可能机理。     

目标?鄄诱饵库搜索策略在蛋白质组质谱鉴定和质控中的应用及研究进展

基于串联质谱的蛋白质组研究会产生海量的质谱数据,这些数据通常使用数据库搜索引擎进行鉴定分析,并根据肽段谱图匹配(PSM)反推真实的样品蛋白质．对于高通量蛋白质组数据的处理,其鉴定结果的可信是后续分析应用的前提,因此对鉴定结果的质量控制尤为重要,而基于目标-诱饵库(target-decoy)搜索策略的质量控制是目前应用最为广泛的方法．本文首先介绍了基于目标-诱饵库搜索策略搜库和质量控制的实施流程,然后综述了基于目标-诱饵库搜索策略的质量控制工具,并提出了目标-诱饵库搜索策略的不足及改善方法,最后对目标-诱饵库搜索策略进行了总结与展望．     

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。