一中国白酒酒曲中的丝状真菌菌群

采用6种不同的培养基,分别于25℃、32℃、42℃以及50℃培养分离从而对某一中国白酒酒曲中的丝状真菌菌群进行研究.从酒曲中共分离得到886株丝状真菌,分属于接合菌,子囊菌和无性型真菌的20属,45种.其中最为丰富的是无性型真菌(28种),其次是接合菌(10种)和子囊菌(7种).对发酵起主要作用的为那些嗜热和耐热的种属,包括:宛氏拟青霉,伞枝梨头霉,梳棉状嗜热丝孢菌,微小根毛霉,金孢霉属一种和红曲属的几个种.文中还对一些在发酵中起重要作用的丝状真菌的特性进行了探讨.     

Detection of Pb²⁺ at attomole levels by using dynamic light scattering and unmodified gold nanoparticles

Lead ion (Pb²⁺) accumulation in nature can affect the environment and human health severely. Thus, rapid and sensitive detection is of great importance. One-step detection of Pb²⁺ at attomole levels was realized by using dynamic light scattering (DLS) technique coupled with unmodified gold nanoparticles (AuNPs). Pb²⁺-dependent DNAzyme was double-stranded and could not adsorb on the surface of AuNPs, while the substrate strand could be cleaved into ssDNA fragments on addition of Pb²⁺. The ssDNA fragments could adsorb on the surface of AuNPs and prevent them from aggregating in the presence of NaCl. Therefore, the disperse state of AuNPs changed on addition of Pb²⁺ in the presence of DNAzyme and NaCl, which was estimated with an average hydrodynamic diameter by using DLS. Under optimum conditions, the average diameter of the solution decreased linearly with the concentration of Pb²⁺ over the range from 10 to 300 pM, with a detection limit of 6.2 pM. Moreover, satisfactory results were obtained when the proposed method was applied in the detection of Pb²⁺ in water samples.     

Crystal structure of HAb18G/CD147: implications for immunoglobulin superfamily homophilic adhesion

CD147, a member of the immunoglobulin superfamily (IgSF), plays fundamental roles in intercellular interactions in numerous pathological and physiological processes. Importantly, our previous studies have demonstrated that HAb18G/CD147 is a novel hepatocellular carcinoma (HCC)-associated antigen, and HAb18G/CD147 stimulates adjacent fibroblasts and HCC cells to produce elevated levels of several matrix metalloproteinases, facilitating invasion and metastasis of HCC cells. In addition, HAb18G/CD147 has also been shown to be a novel universal cancer biomarker for diagnosis and prognostic assessment of a wide range of cancers. However, the structural basis underlying the multifunctional character of CD147 remains unresolved. We report here the crystal structure of the extracellular portion of HAb18G/CD147 at 2.8A resolution. The structure comprises an N-terminal IgC2 domain and a C-terminal IgI domain, which are connected by a 5-residue flexible linker. This unique C2-I domain organization is distinct from those of other IgSF members. Four homophilic dimers exist in the crystal and adopt C2-C2 and C2-I dimerization rather than V-V dimerization commonly found in other IgSF members. This type of homophilic association thus presents a novel model for homophilic interaction between C2 domains of IgSF members. Moreover, the crystal structure of HAb18G/CD147 provides a good structural explanation for the established multifunction of CD147 mediated by homo/hetero-oligomerizations and should represent a general architecture of other CD147 family members.     

哺乳仔猪中伪狂犬病病毒鄂A株对细胞凋亡的诱导或抑制

通过人工感染伪狂犬病病毒阴性的健康仔猪 ,取实验组和阴性对照组仔猪的咽部扁桃体、胸腺、颈部淋巴结、腹股沟淋巴结、大脑、小脑、嗅球、三叉神经节等组织作样本。通过电子显微镜观察、DNA梯谱和原位末端脱氧核苷酸标记等试验进行细胞凋亡分析 ,结果发现实验组仔猪的淋巴组织细胞呈现典型的细胞凋亡的特征 ,而神经组织中无。这一结果表明 :伪狂犬病病毒感染诱导大量淋巴细胞凋亡 ,造成仔猪免疫功能低下 ,导致大量死亡 ,这可能是伪狂犬病病毒急性感染致病机制之一 ;同时也证实伪狂犬病病毒通过抑制神经细胞的凋亡 ,在神经组织中建立潜伏感染并终生带毒。     

Characterization of Outer Membrane Proteins of Escherichia Coli in Response to Phenol Stress

Gram-negative bacteria are generally more tolerant to disinfectants than Gram-positive bacteria due to outer membrane (OM) barrier, but the tolerant mechanism is not well characterized. We have utilized comparative proteomic methodologies to characterize the OM proteins of E. coli K-12 K99+ in response to phenol stress and found that nine proteins were altered significantly. They were OM proteins OmpA, FadL, LamB, and OmpT, cytoplasmic-associated proteins AceA and EF-Tu, inner membrane protein AtpB, putative capsid protein Q8FewO, and unknown location protein Dps. They were reported here for the first time to be phenol-tolerant proteins. The alteration and functional characterization of the four OM proteins were further investigated using western blotting, genetically modified strains with gene deletion and gene complementation approaches. Our results characterized the functional OM proteins of E. coli in resistance to phenol, and provide novel insights into the mechanisms of bacterial disinfectant-tolerance and new drug targets for control of phenol-resistant bacteria.     

稻株上拮抗细菌的定殖及其对土著细菌的影响

在温室条件下,通过分批播种、接种纹枯病菌Rhizoctonia solani,以及在水稻分孽盛期喷雾拮抗细菌Pseudomonas fluorescens Pf7-14 (天然的抗萘啶酮酸菌株) 和B5423-R(Bacillus subtilis B5423的利福平抗性突变体)的菌悬浮液,并通过定期取样,平板系列稀释法回收,测定了菌株Pf7-14、B5423-R和土著细菌群体在水稻健株和纹枯病株上的种群数量,所获结果如下:①当相同的浓度(约2.0×108cfu/ml)的菌悬浮液喷雾到叶片时,菌株Pf7-14定殖的时间比菌株B5423-R长,且在相同的时间内,菌株Pf7-14的平均群体数量高于菌株B5423-R;②在健康的水稻茎部,菌株Pf7-14的两个高、低不同浓度处理的平均群体数量均表现出随时间降低的趋势;相比,较低浓度(4.0×107cfu/ml)的B5423-R在茎部的平均群体数量随着时间的下降,而较高浓度(2.0×108cfu/ml)的B5423-R的平均群体数量在水稻乳熟至黄熟期保持稳定或略有增长;③当病斑面积占取样茎面积的比率为20%～35%时,在应用1和14d后菌株Pf7-14在健茎的平均群体数量分别是病茎的6倍多和2倍多,差异均达到显著性的水平(P=0.05),而菌株B5423-R 在应用1d后病茎的数量比在健茎显著性地低大约1倍,但在7～14d后,病茎的数量比在健茎显著性地高5～6倍,群体在病茎表现出相对的增长;④土著细菌群体在病斑茎部是健茎的6～7倍.这些结果表明两类拮抗细菌有着明显不同的定殖习性,在病斑上B5423比Pf7-14具有更强的竞争能力,是一类更好的生防制剂;同时表明引入的拮抗细菌同土著细菌群体在营养和空间上竞争激烈,且土著细菌群体更具有竞争优势.     

根系分泌物介导下植物-土壤-微生物互作关系研究进展与展望

根系分泌物是植物与土壤进行物质交换和信息传递的重要载体物质, 是植物响应外界胁迫的重要途径, 是构成植物不同根际微生态特征的关键因素, 也是根际对话的主要调控者。根系分泌物对于生物地球化学循环、根际生态过程调控、植物生长发育等均具有重要功能, 尤其是在调控根际微生态系统结构与功能方面发挥着重要作用, 调节着植物-植物、植物-微生物、微生物-微生物间复杂的互作过程。植物化感作用、作物间套作、生物修复、生物入侵等都是现代农业生态学的研究热点, 它们都涉及十分复杂的根际生物学过程。越来越多的研究表明, 不论是同种植物还是不同种植物之间相互作用的正效应或是负效应, 都是由根系分泌物介导下的植物与特异微生物共同作用的结果。近年来, 随着现代生物技术的不断完善, 有关土壤这一“黑箱”的研究方法与技术取得了长足的进步, 尤其是各种宏组学技术(meta-omics technology), 如环境宏基因组学、宏转录组学、宏蛋白组学、宏代谢组学等的问世, 极大地推进了人们对土壤生物世界的认知, 尤其是对植物地下部生物多样性和功能多样性的深层次剖析, 根际生物学特性的研究成果被广泛运用于指导生产实践。深入系统地研究根系分泌物介导下的植物-土壤-微生物的相互作用方式与机理, 对揭示土壤微生态系统功能、定向调控植物根际生物学过程、促进农业生产可持续发展等具有重要的指导意义。该文综述了根系分泌物的概念、组成及功能, 论述了根系分泌物介导下植物与细菌、真菌、土壤动物群之间的密切关系, 总结了探索根际生物学特性的各种研究技术及其优缺点, 并对该领域未来的研究方向进行了展望。     

Protein identification assisted by the prediction of retention time in liquid chromatography/tandem mass spectrometry

Two-dimensional liquid chromatography (2D-LC) coupled on-line with electrospray ionization tandem mass spectrometry (2D-LC-ESI-MS/MS) is a new platform for analysis and identification of proteome. Peptides are separated by 2D-LC and then performed MS/MS analysis by tandem MS/MS. The MS/MS data are searched against database for protein identification. In one 2D-LC-ESI-MS/MS run, we obtained not only the structural information of peptides directly from MS/MS, but also the retention time of peptides eluted from LC. Information on the chromatographic behavior of peptides can assist protein identification in the new platform for proteomics. The retention time of the matching peptides of the identified protein was predicted by the hydrophobic contribute of each amino acid on reversed-phase liquid chromatography (RPLC). By using this strategy proteins were identified by four types of information: peptide mass fingerprinting (PMF), sequence query, and MS/MS ions searched and the predicted retention time. This additional information obtained from LC could assist protein identification with no extra experimental cost.     

Litter addition and understory removal influenced soil organic carbon quality and mineral nitrogen supply in a subtropical plantation forest

Plant and Soil - Aboveground litter inputs have been modified by global changes in plantation forests, where understory management is also prevalent, which may alter soil fertility and stand...     

细菌外膜蛋白参与革兰氏阴性细菌对异丙醇耐受的调节

细菌外膜蛋白与细菌对异丙醇耐受关系密切,但迄今为止尚未见相关研究.本文首先采用基于双向电泳(two dimensional electrophoresis,2-DE)的蛋白质组学技术,研究E.coli K-12 BW25113在有无异丙醇条件下外膜蛋白表达的差异.结果发现,外膜蛋白LamB、FadL和OmpC以及OmpT、Tsx、OmpA和OmpF在异丙醇应激条件下表达量分别上调和下调.然后通过基因敲除、补救和高表达等功能基因组学的方法,探讨这些功能外膜蛋白在异丙醇应激耐受中所起的作用,发现LamB、OmpA和OmpC在E.coli K-12 BW25113对异丙醇耐受过程中起到更重要的作用.最后,对EnvZ/OmpR双组分信号转导系统在对异丙醇耐受中的作用进行了研究,证实EnvZ/OmpR双组分信号转导系统确实参与细菌对异丙醇的耐受.因此,外膜蛋白的改变和EnvZ/OmpR双组分信号转导系统的调节是革兰氏阴性细菌对异丙醇耐受的一种重要机制。