克鲁斯假丝酵母及其近似种的脉冲电泳核型分析

用钳位均匀电场脉冲电泳(CHEF)系统分析了克鲁斯假丝酵母(Candida krusei),郎比可假丝酵母(C. lambica)和粗状假丝酵母(C. valiad)的模式菌株的电泳核型,发现这三种表型相似的假丝酵母却具有互不相同的染色体DNA分子带型,为其分类学研究提供了可靠的鉴别依据。在常规分类学研究的基础上,测定了AS 2.75(原定种名为(C. incospicua),AS2.1182(原定种名为 C. lambica)和AS 2.1772(未定种)等三株假丝酵母的G+C含量和脉冲电泳核型。通过对已报道的C. inconspicu的G+C含量及上述三种假丝酵母模式菌株的脉冲电泳核型的比较分析证明,AS 2.75和AS 2.1772为粗状假丝酵母(C. valida),AS 2.1182为克鲁斯假丝酵母(C. krusei)。     

基于23S／5SrDNA序列的柑橘黄龙病病原菌亚洲种系统发育研究

根据柑橘黄龙病亚洲种23S/5S的DNA序列设计一对引物对不同地理来源的6个柑橘黄龙病样品DNA进行扩增,扩增片段大小均为1 654 bp包括一个假定细胞壁水解酶假基因(putative cell wall hydrolase pseudogene)和5S rRNA 基因.序列同源性分析结果表明;6个柑橘黄龙病病原菌样品与柑橘黄龙病病原菌亚洲种Sihui样品的同源性为99%,然而与土壤杆菌,布鲁氏菌,根瘤菌,中华根瘤菌,巴通体菌和中慢生根瘤菌的同源性只有89%～95%,说明在23S/5S rDNA序列上黄龙病病原菌亚洲种与α变形菌纲根瘤菌目的其他病原菌相差较大.对黄龙病病原菌亚洲种种内的23S/5S rDNA序列进行比较分析,结果发现黄龙病病原菌亚洲种种内之间putative cell wall hydrolase pseudogene和5S rRNA的基因序列非常保守,但不同地理来源的柑橘黄龙病样品碱基序列间确实存在差异,差异的大小与地理的远近无关.利用简约法对黄龙病病原菌亚洲种及α变形菌纲其它病原菌的23S/5S rDNA序列构建的系统发育树显示黄龙病病原菌亚洲种单独聚为一类,其他细菌聚为另一类,该结果与基于rplJ基因及16S rRNA基因的DNA序列构建的分子系统进化树结果一致.     

Apoptosis is involved in the senescence of endothelial cells induced by angiotensin II

Vascular endothelial cells have a finite cell lifespan and eventually enter an irreversible growth arrest, cellular senescence. The functional changes associated with cellular senescence are thought to contribute to human aging and age-related cardiovascular disorders, e.g. atherosclerosis. In this study, induction of Angiotensin II (Ang II) promoted a growth arrest with phenotypic characteristics of cell senescence, such as enlarged cell shapes, increased senescence-associated beta-galactosidase (SA-beta-gal) positive staining cell, and depressed cell proliferation. Apoptotic changes were increased in senescent cells, with a small subset of the senescent cells showing aberrant morphology such as pronounced nuclear fragmentation or multiple micronuclei. The results suggest cell apoptosis is possibly an important factor in the process of pathologic and physiologic senescence of endothelial cells as well as vascular aging.     

Draft genome sequence of Streptomyces coelicoflavus ZG0656 reveals the putative biosynthetic gene cluster of acarviostatin family α-amylase inhibitors

Aims: The aims of this study are to obtain the draft genome sequence of Streptomyces coelicoflavus ZG0656, which produces novel acarviostatin family α‐amylase inhibitors, and then to reveal the putative acarviostatin‐related gene cluster and the biosynthetic pathway. Methods and Results: The draft genome sequence of S. coelicoflavus ZG0656 was generated using a shotgun approach employing a combination of 454 and Solexa sequencing technologies. Genome analysis revealed a putative gene cluster for acarviostatin biosynthesis, termed sct‐cluster. The cluster contains 13 acarviostatin synthetic genes, six transporter genes, four starch degrading or transglycosylation enzyme genes and two regulator genes. On the basis of bioinformatic analysis, we proposed a putative biosynthetic pathway of acarviostatins. The intracellular steps produce a structural core, acarviostatin I00‐7‐P, and the extracellular assemblies lead to diverse acarviostatin end products. Conclusions: The draft genome sequence of S. coelicoflavus ZG0656 revealed the putative biosynthetic gene cluster of acarviostatins and a putative pathway of acarviostatin production. Significance and Impact of the Study: To our knowledge, S. coelicoflavus ZG0656 is the first strain in this species for which a genome sequence has been reported. The analysis of sct‐cluster provided important insights into the biosynthesis of acarviostatins. This work will be a platform for producing novel variants and yield improvement.     

Hydrological regulation drives regime shifts: evidence from paleolimnology and ecosystem modeling of a large shallow Chinese lake

Quantitative evidence of sudden shifts in ecological structure and function in large shallow lakes is rare, even though they provide essential benefits to society. Such ‘regime shifts’ can be driven by human activities which degrade ecological stability including water level control (WLC) and nutrient loading. Interactions between WLC and nutrient loading on the long‐term dynamics of shallow lake ecosystems are, however, often overlooked and largely underestimated, which has hampered the effectiveness of lake management. Here, we focus on a large shallow lake (Lake Chaohu) located in one of the most densely populated areas in China, the lower Yangtze River floodplain, which has undergone both WLC and increasing nutrient loading over the last several decades. We applied a novel methodology that combines consistent evidence from both paleolimnological records and ecosystem modeling to overcome the hurdle of data insufficiency and to unravel the drivers and underlying mechanisms in ecosystem dynamics. We identified the occurrence of two regime shifts: one in 1963, characterized by the abrupt disappearance of submerged vegetation, and another around 1980, with strong algal blooms being observed thereafter. Using model scenarios, we further disentangled the roles of WLC and nutrient loading, showing that the 1963 shift was predominantly triggered by WLC, whereas the shift ca. 1980 was attributed to aggravated nutrient loading. Our analysis also shows interactions between these two stressors. Compared to the dynamics driven by nutrient loading alone, WLC reduced the critical P loading and resulted in earlier disappearance of submerged vegetation and emergence of algal blooms by approximately 26 and 10 years, respectively. Overall, our study reveals the significant role of hydrological regulation in driving shallow lake ecosystem dynamics, and it highlights the urgency of using multi‐objective management criteria that includes ecological sustainability perspectives when implementing hydrological regulation for aquatic ecosystems around the globe.     

人骨髓间充质干细胞在成年大鼠脑内的迁移及分化

骨髓间充质干细胞 (mesenchymalstemcells,MSCs)是目前备受关注的一类具有多向分化潜能的组织干细胞 ,体外可以分化为骨、软骨、脂肪等多种细胞。因此 ,MSCs是细胞治疗和基因治疗的种子细胞之一。为了探索MSCs的迁移和分化趋势 ,为帕金森病 (Parkinsondisease,PD)的干细胞治疗提供理论和实验依据 ,本实验将体外扩增并转染增强型绿色荧光蛋白 (enhancedgreenfluorescentprotein ,EGFP)的人骨髓MSCs注入PD大鼠脑内纹状体 ,观察了人骨髓MSCs在大鼠脑内的存活、迁移、分化以及注射MSCs前后大鼠的行为变化。结果表明 ,人骨髓MSCs在大鼠脑内可存活较长时间 ( 10周以上 ) ;随着时间的延长 ,MSCs迁移范围扩大 ,分布于纹状体、胼胝体、皮质以及脑内血管壁 ;免疫组化法检测证实MSCs在大鼠脑内表达人神经丝蛋白 (neurofilament,NF)、神经元特异性烯醇化酶 (neuron specificeno lase,NSE)以及胶质原纤维酸性蛋白 ( glialfibrillaryacidprotein ,GFAP) ;PD大鼠的异常行为有所缓解 ,转圈数由 8 86±2 0 9r/min下降到 4 87± 2 0 6r/min ,统计学分析P <0 0 5为差异显著。以上观察结果表明 ,骨髓MSCs有望成为治疗PD的种子细胞     

Spectroscopic characterization and molecular weight distribution of dissolved organic matter in sediment porewaters from Lake Erhai, Southwest China

Dissolved organic matter (DOM) in sediment porewaters from Lake Erhai, Southwest China was investigated using dissolved organic carbon (DOC) concentration, UV absorbance, fluorescence and molecular weight distribution. DOC exhibited a high concentration at the sediment–water interface with a rapid decrease to the oxic–anoxic interface at approximately 7 cm, and then increased with depth. Similar trends were also found for the UV absorption coefficients at 254 and 280 nm in the porewaters. DNA in the sediment was also measured, which confirmed the high abundance of aerobic bacteria in the upper layer of the sediment. Both humic-like (peaks A and C) and protein-like (peaks B and D) fluorescence were observed in the porewater DOM, and their fluorescence intensities exhibited a similar porewater profile as DOC concentration. A strong correlation was found between the peak fluorescence intensity ratio r(A, C) and r(D, B). Both the fluorescence index and UV absorption coefficient at 254 nm suggested a dramatic increase in aromaticity of porewater DOM across the oxic–anoxic interface. Porewater DOM exhibited a multimodal distribution of molecular weight with a relatively low polydispersity. The results of this study offer significant insight into the nature and properties of DOM in freshwater ecosystems.     

Synaptic neurotransmission depression in ventral tegmental dopamine neurons and cannabinoid-associated addictive learning

Drug addiction is an association of compulsive drug use with long-term associative learning/memory. Multiple forms of learning/memory are primarily subserved by activity- or experience-dependent synaptic long-term potentiation (LTP) and long-term depression (LTD). Recent studies suggest LTP expression in locally activated glutamate synapses onto dopamine neurons (local Glu-DA synapses) of the midbrain ventral tegmental area (VTA) following a single or chronic exposure to many drugs of abuse, whereas a single exposure to cannabinoid did not significantly affect synaptic plasticity at these synapses. It is unknown whether chronic exposure of cannabis (marijuana or cannabinoids), the most commonly used illicit drug worldwide, induce LTP or LTD at these synapses. More importantly, whether such alterations in VTA synaptic plasticity causatively contribute to drug addictive behavior has not previously been addressed. Here we show in rats that chronic cannabinoid exposure activates VTA cannabinoid CB1 receptors to induce transient neurotransmission depression at VTA local Glu-DA synapses through activation of NMDA receptors and subsequent endocytosis of AMPA receptor GluR2 subunits. A GluR2-derived peptide blocks cannabinoid-induced VTA synaptic depression and conditioned place preference, i.e., learning to associate drug exposure with environmental cues. These data not only provide the first evidence, to our knowledge, that NMDA receptor-dependent synaptic depression at VTA dopamine circuitry requires GluR2 endocytosis, but also suggest an essential contribution of such synaptic depression to cannabinoid-associated addictive learning, in addition to pointing to novel pharmacological strategies for the treatment of cannabis addiction.     

一种新的DyP-type过氧化物酶在大肠杆菌中的重组表达、纯化及鉴定

染料脱色过氧化物酶(DyP-type过氧化物酶)是含有亚铁血红素,能降解各种有毒染料的一类蛋白.为了研究运动发酵单胞菌Zymomonas mobilis ZM4 (ATCC 31821)中一种新的DyP-type过氧化物酶的特点和功能,以Z.mobilis基因组DNA为模板,通过PCR扩增目的基因,克隆到大肠杆菌表达载体pET-21b(+)中.通过ZmDyP与其他DyP-type过氧化物酶的比对,发现它们存在着共同保守氨基酸D149、R239、T254、F256和GXXDG结构基序,说明ZmDyP是Dyp-type过氧化物酶家族的一个新成员.经IPTG诱导大肠杆菌中pET21 b(+)-ZmDyP表达,并将表达的酶进行金属螯合层析纯化.SDS-PAGE分析表明,纯酶分子量为36 kDa,而活性染色显示分子量为108 kDa,表明该酶在活性状态下可能是一个三聚体.光谱扫描显示ZmDyP有一个典型的亚铁血红素吸收峰,说明它是含有亚铁血红素的蛋白.对ZmDyP性质进行了研究,发现以2,2-二氨-双(3-乙基苯并噻唑-6-磺酸)ABTS为底物,ZmDyP表现出更高的转化效率.这些研究结果丰富了DyP-type 过氧化物酶家族信息,并且为ZmDyP的结构功能和反应机制研究奠定了基础.