黄粉虫抗菌肽在大肠杆菌中表达条件优化及活性分析

为了提高黄粉虫抗菌肽基因tmAMP1m在大肠杆菌中的表达量,研究了培养温度、诱导时间及IPTG浓度等不同条件对HIS-TmAMP1m融合蛋白表达量和活性的影响。通过Tricine-SDS-PAGE分析确定最佳表达条件,同时,通过琼脂孔穴扩散法检测其抑菌活性。结果表明,含有重组质粒的大肠杆菌在37℃,使用终浓度为0.1 mmol/L IPTG培养4 h时,融合蛋白表达量较高,可占细菌总蛋白40%以上,抗菌活性最好。用Ni2+亲和层析纯化获得较纯的融合蛋白,Western blotting分析表明其能与His单克隆抗体起特异性反应。诱导表达的融合蛋白对宿主菌生长产生一定程度抑制。融合蛋白经100℃煮沸10 h,在20℃反复冻融10次,与强酸强碱缓冲液、不同的有机溶剂和蛋白酶混合后都具有极强的稳定性,仍然表现出良好的抗菌活性。此外,最小抑菌浓度(MIC)测定结果表明,融合蛋白对5种菌具有良好的抗菌活性。研究结果为昆虫抗菌肽推广应用和进一步研究奠定了基础。     

Integrating Culture-based Antibiotic Resistance Profiles with Whole-genome Sequencing Data for 11,087 Clinical Isolates

Emerging antibiotic resistance is a major global health threat. The analysis of nucleic acid sequences linked to susceptibility phenotypes facilitates the study of genetic antibiotic resistance determinants to inform molecular diagnostics and drug development. We collected genetic data(11,087 newly-sequenced whole genomes) and culture-based resistance profiles(10,991 out of the11,087 isolates comprehensively tested against 22 antibiotics in total) of clinical isolates including18 main species spanning a time period of 30 years. Species and drug specific resistance patterns were observed including increased resistance rates for Acinetobacter baumannii to carbapenems and for Escherichia coli to fluoroquinolones. Species-level pan-genomes were constructed to reflect the genetic repertoire of the respective species, including conserved essential genes and known resistance factors. Integrating phenotypes and genotypes through species-level pan-genomes allowed to infer gene–drug resistance associations using statistical testing. The isolate collection and the analysis results have been integrated into GEAR-base, a resource available for academic research use free of charge at https://gear-base.com.     

麻雀幼鸟和成鸟逃逸距离的比较

逃逸是鸟类常用的反捕食手段。自然选择会优化鸟类的逃逸距离,以便在躲避被捕食风险和保持能量之间做出权衡。理论模型预测动物个体可依据期望寿命来调整自身的行为：期望寿命短的个体倾向于风险偏好,即逃逸距离短;而期望寿命长的个体倾向于风险回避,即逃逸距离长。同时,逃逸距离还受到外部因素（如人为干扰强度、鸟类群体大小）的影响。本研究在北京城区收集了麻雀（Passer montanus）145只成鸟和75只幼鸟的逃逸距离数据,发现麻雀成鸟比幼鸟有着更长的逃逸距离,且成鸟更可能是群体中首先逃逸的个体。此外,研究发现麻雀的逃逸距离随着人为干扰强度的增加而降低,随着群体大小增加而增加。本研究结果符合理论预期：存活率高的类群（成鸟）有着更长的逃逸距离。     

Cellulose structure and lignin distribution in normal and compression wood of the Maidenhair tree(Ginkgo biloba L.)

We studied in detail the mean micro fibril angle and the width of cellulose crystals from the pith to the bark of a 15-year-old Maidenhair tree(Ginkgo biloba L.). The orientation of cellulose micro fibrils with respect to the cell axis and the width and length of cellulose crystallites were determined using Xray diffraction. Raman microscopy was used to compare the lignin distribution in the cell wall of normal/opposite and compression wood, which was found near the pith. Ginkgo biloba showed a relatively large mean micro fibril angle,varying between 19° and 39° in the S2 layer, and the average width of cellulose crystallites was 3.1–3.2 nm. Mild compression wood without any intercellular spaces or helical cavities was observed near the pith. Slit-like bordered pit openings and a heavily lignified S2 L layer con firmed the presence of compression wood. Ginkgo biloba showed typical features present in the juvenile wood of conifers. The micro fibril angle remained large over the 14 annual rings. The entire stem disc,with a diameter of 18 cm, was considered to consist of juvenile wood. The properties of juvenile and compression wood as well as the cellulose orientation and crystalline width indicate that the wood formation of G. biloba is similar to that of modern conifers.     

鼻息肉与鼻咽癌标本VEGF水平及微血管密度对比及其临床意义

目的:对比研究鼻咽癌和鼻息肉标本中VEGF表达强度及MVD差异,同时分析VEGF、MVD和鼻咽癌临床特征的相关性。方法:纳入我科就诊的鼻咽癌患者57例,鼻息肉患者50例。采用免疫组化SABC法检测癌组织、癌旁组织、及息肉组织中中VEGF蛋白的表达,及MVD强度。分析VEGF、MVD和鼻咽癌患者性别、临床分期、颈部淋巴结转移、远处转移、血清EBV-Ig A阳性、WHO病理分型相关性。统计分析随访结果,对可能影响鼻咽癌预后的因素进行Cox回归模型分析。结果:鼻咽癌组织、鼻咽癌旁组织、鼻息肉组织中VEGF表达、MVD强度具有明显差异(p0.05)。不同鼻咽癌临床分期、是否发生远处转移、不同WHO病理分型和VEGF表达、MVD强度具有明显差异(p0.05)。Cox回归方程显示,远处转移、病理分型、VEGF表达强度是影响鼻咽癌生存的独立危险因素(p0.05)。结论:鼻咽癌高表达VEGF,促进新生血管,形成高密度微小血管,和鼻咽癌远处转移密切相关,降低其生存率。     

Identification of four novel DC-SIGN ligands on Mycobacterium bovis BCG

Dendritic-cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN; CD209) has an important role in mediating adherence of Mycobacteria species, including M. tuberculosis and M. bovis BCG to human dendritic cells and macrophages, in which these bacteria can survive intracellularly. DC-SIGN is a C-type lectin, and interactions with mycobacterial cells are believed to occur via mannosylated structures on the mycobacterial surface. Recent studies suggest more varied modes of binding to multiple mycobacterial ligands. Here we identify, by affinity chromatography and mass-spectrometry, four novel ligands of M. bovis BCG that bind to DC-SIGN. The novel ligands are chaperone protein DnaK, 60 kDa chaperonin-1 (Cpn60.1), glyceraldehyde-3 phosphate dehydrogenase (GAPDH) and lipoprotein lprG. Other published work strongly suggests that these are on the cell surface. Of these ligands, lprG appears to bind DC-SIGN via typical protein-glycan interactions, but DnaK and Cpn60.1 binding do not show evidence of carbohydrate-dependent interactions. LprG was also identified as a ligand for DC-SIGNR (L-SIGN; CD299) and the M. tuberculosis orthologue of lprG has been found previously to interact with human toll-like receptor 2. Collectively, these findings offer new targets for combating mycobacterial adhesion and within-host survival, and reinforce the role of DC-SIGN as an important host ligand in mycobacterial infection.     

干旱区绿洲土地利用/覆被及景观格局变化特征——以新疆精河县为例

从宏观上运用3S技术,利用1972年MSS、1990年Landsat TM、2001年Landsat ETM+和2005年CBERS 4个时期遥感影像数据,将GIS和景观生态学的数量分析方法相结合,运用ArcGIS以及Fragstats,分析了干旱区绿洲精河县1972～2005年间的土地利用/覆被和景观格局的变化.结果表明:(1)1972～2005年的33a中,精河县LUCC的总体变化趋势是绿洲面积有小幅度扩张,其中人工绿洲面积扩张尤为显著,天然绿洲面积减少.(2)研究区水域面积的变化受艾比湖湖面面积的变化影响较大,变化不显著,但总体上呈缓慢增长的趋势.(3)盐渍地面积的变化经历了先扩张后减小的一个过程.1990年达到最大值,但到2005年面积又有很大程度减少.沙地面积小幅度减小,其他地类的面积始终呈增加趋势.(4)景观在各个研究时段也发生显著变化.总的来说,整个研究区景观的密度持续增大,最大斑块指数先减小后增大,面积加权形状指数减小,形状趋于规则;斑块间的最邻近距离减小.表明1972年时景观中的优势斑块类型的连接性较2005年好,逐渐向具有多种要素的密集格局演变,景观更加破碎.同时不同斑块间的分离度增大,也说明景观破碎化程度加深.从香农多样性指数和香农均度指数的变化可以看出,景观的多样性增加,且均度增强.景观多样性及破碎化程度增加,也反映了土地利用越来越丰富.总之,要实现区域土地资源的可持续发展和景观生态功能的良性发挥,必须注重土地利用格局优化,维护景观生态过程与格局的连续性.     

Thoughts of a Travelling Ecologist, 6 On monitoring

Monitoring. We, ecologists, hear the word nearly every day. From the most unexpected corners this word springs out, much used and abused. One one hand, it is often used by my peers to justify their work, their project or even their existence as scientists. They claim to do useful work, because they monitor some phenomenon or another. This, goes the argument, is essential for the continued survival of … generally, nothing less than humankind.     

猪流感病毒进化方式及其流行特点

摘要：猪在甲型流感病毒生态分布和遗传进化中占有重要地位。猪的呼吸道上皮同时具有禽和人流感病毒2种类型的受体,因此人和禽流感病毒都可以感染猪,猪被认为是禽、人流感病毒的中间宿主和不同来源流感病毒的基因“混合器”。猪流感病毒（Swine influenza virus, SIV）的进化方式包括基因重配、抗原漂移和宿主适应性进化,其中基因重配是主要进化方式。与人类季节性流感病毒相比,SIV在全球的流行情况各不相同,呈地方流行性,并具有明显的地区差异。全球范围内流行的SIV亚型主要有3种：H1N1、H3N2和H1N2亚型,其中各亚型内病毒基因来源又不尽相同。欧洲、北美及我国猪群中流行的流感病毒在遗传进化和基因来源方面各具特色。目前欧洲猪群中流行的主要是类禽H1N1、H1N2和H3N2病毒,其中后两者是基因重配病毒。从1998年开始,古典猪H1N1、“人-猪-禽”三源基因重配H3N2、H1N1和H1N2病毒共存于北美的猪群中,其遗传变异日趋复杂。在基因进化上,欧洲和北美基因重配的SIV是目前新的人类大流感病毒-“甲型H1N1病毒”-的母源病毒。我国猪群中流感病毒主要是古典猪H1N1和类人H3N2病毒,但近年来在我国猪群中分离到遗传上与欧洲和北美SIV高度相关的病毒,提示我国SIV的进化趋势值得关注。1970年代以来,全球已报道了50多起人感染SIV事件,表明SIV也是一种值得重视的人兽共患病,预示了SIV可能成为人类大流感毒株或为大流感毒株提供基因。鉴于SIV在甲型流感病毒生态学上的重要意义,以及对人类公共卫生的潜在威胁,建议应尽早启动我国SIV的常规监测工作,密切关注SIV的流行动态,掌握其分子遗传进化规律。同时,将SIV的监测工作纳入整个流感病毒（人和动物流感病毒）的监测网络,在信息上实现共享,从生态学的高度把握我国流感病毒的流行和进化趋势,这对保护动物健康和预防人类大流感都有重要意义。