一种快速提取细菌总DNA的方法研究

随着分子生物学技术应用于环境微生物研究的深入开展,占自然界微生物物种总数的90%以上的不能人工培养或培养困难的微生物已经可以借助分子生物学技术进行功能基因的开发和利用。而快速得到纯度较高,结构完整的细菌染色体DNA成为这一技术得以实现的前提。本文报道了利用高温处理和SDS的裂解作用相结合而建立的一种快速、简便的提取细菌染色体DNA的方法。经过脉冲电泳实验证明,利用本方法提取得到的几种革兰氏阳性和革兰氏阴性菌株的基因组DNA结构完整,并且无明显降解,无须经过纯化,可以直接进行PCR扩增和酶切等分子生物学操作,将此方法进一步应用于土壤环境DNA的提取方面,同样达到了快速得到大片段、高质量的环境微生物基因组的目的,为研究未培养的环境微生物多样性打下了坚实的基础,同时为环境基因组的提取提供了一个新的途径。     

Allelopathic control of cyanobacterial blooms by periphyton biofilms

Periphyton biofilms are natural mixtures comprised of photoautotrophic and heterotrophic complex microorganisms. In this work, the inhibition effects of periphyton biofilms on cyanobacterial blooms were studied in pilot and field trials. Results show that the cyanobacterial species responsible for the blooms had an upper nutrient concentration threshold, below which it could not effectively compete with other organisms in the periphyton. The disappearance of the cyanobacterial blooms was due to the allelopathy between the cyanobacteria and periphyton biofilm. In particular, it was found that the periphyton biofilm could produce water-soluble allelochemicals such as indole and 3-oxo-α-ionone to significantly inhibit the growth of the cyanobacteria. These allelochemicals are able to damage the thylakoid membranes of the cyanobacteria, interrupt the electron transport in photosystem II, decrease effective quantum yields, and eventually lead to the failure of photosynthesis. A comprehensive discussion on the ecological consequences of these findings is also presented. This work demonstrates the potential of periphyton biofilm to be used as an environmentally friendly ecological engineering solution for (i) the control of cyanobacterial blooms and (ii) a transitional means for the construction of beneficial conditions for ecosystem restoration. In addition, this work provides significant insights into the competitive relationships between algae and biofilms.     

Evaluation of p38 MAPK pathway as a molecular signature in ulcerative colitis

Early diagnosis and treatment of ulcerative colitis (UC) is clinically challenging. To overcome this problem, we explored the interrelated multiplex signaling pathway to identify molecular signatures in UC by using integrated strategy in proteomics. Intestinal mucosa of 12 UC cases and 12 normal controls underwent comparative proteomic analysis. A total of 26 unique differential proteins were identified, including 12 up-regulated and 14 down-regulated in UC group. A differential protein cluster, consisting of 11 proteins involved in p38 mitogen-activated protein kinase (MAPK) pathway, was deduced and validated by Western blot. Furthermore, three proteins elicited from the protein cluster, phosphorylated p38, MAWBP and galectin-3, as a molecular signature, were analyzed by immunohistochemistry on 118 UC and normal samples. Increased expression of P-p38 and down-regulated MAWBP and/or galectin-3 were detected in UC compared to normal samples (p < 0.001). This signature correlated with disease progression of UC (p < 0.01), and classified UC risk with high sensitivity (94.83 ± 2.91%) and specificity (98.33 ± 1.65%). In addition, P38 MAPK pathway modulated the expression of the protein clusters in macrophage cell line as evidenced by the alteration with specific inhibitor SB203580. These results indicate that molecular signature of P38 MAPK pathway might be a potential biomarker for evaluating UC risk.     

土壤中聚乙烯降解菌的筛选、鉴定及降解特性

[目的] 农用地膜主要成分为聚乙烯（polyethylene,PE）,因其难以被降解,其废弃物常造成“白色污染”,本研究从常年覆盖农用地膜的土壤中筛选PE降解菌,并探究其对PE制品的降解效能。[方法] 采集的土壤样品用PE为唯一碳源的无机盐培养基进行富集,筛选、纯化PE降解菌,分离菌通过形态染色、生理生化特征、16S rRNA基因序列分析进行鉴定,检测其在不同PE浓度（0%、0.05%、0.10%、0.25%、0.50%、1.00%、2.00%、3.00%）的无机盐培养基中的生长曲线,最后通过扫描电镜、光镜观察,检测分离菌对农用地膜的降解效能。[结果] 从土壤中筛选获得一株能够降解PE的分离菌株（命名为SW1）,初步鉴定其为放线菌的诺卡氏菌属Nocardia sp.。SW1的生长对PE具有明显浓度依赖,在含2% PE的无机盐培养基中生长最快,在培养的第48 h菌液浓度开始明显增加,第60 h达到最大,而在不含PE的无机盐培养基中未见生长。形态生理学观察表明,35℃培养15 d后,扫描电镜观察可见有大量菌嵌入膜内或附于膜表面生长,膜表面粗糙,并开始出现破损;培养60 d后,光镜观察可见膜大面积破损,并出现空洞。[结论] 从土壤中筛选获得了一株能够有效降解PE制品的放线菌菌株Nocardia sp. SW1。该研究丰富了PE制品降解微生物的菌种资源,为PE塑料废弃物的生物降解提供了科学数据与参考。     

小麦不同蘖位叶片出生的两段线性模式及其品种、播期效应

叶片出生动态是小麦生长发育进程及其协调状况的重要表现,研究发现,小科叶片出生与播后累积ＧＤＤ（ｆｇｒｏｗｉｎｇ ｄｅｇｒｅｅ ｄａｙｓ ａｆｔｅｒ ｓｏｗｉｎｇ）的关系遵循两段（阶段Ⅰ快于阶段Ⅱ）线性模式,护颖分化期为两段模式的分界点,这一规律在正常发育的冬性和春性品种的７主茎及分蘖中表现一致,冬性品种播期１（９月３０日）、播期３（３月２日）的主茎及冬、春性品种各播期的Ｔ３分蘖,因生长发育异常而”     

Assembly of retrovirus capsid-nucleocapsid proteins in the presence of membranes or RNA

Retrovirus Gag precursor (PrGag) proteins direct the assembly of roughly spherical immature virus particles, while after proteolytic processing events, the Gag capsid (CA) and nucleocapsid (NC) domains condense on viral RNAs to form mature retrovirus core structures. To investigate the process of retroviral morphogenesis, we examined the properties of histidine-tagged (His-tagged) Moloney murine leukemia (M-MuLV) capsid plus nucleocapsid (CANC) (His-MoCANC) proteins in vitro. The His-MoCANC proteins bound RNA, possessed nucleic acid-annealing activities, and assembled into strand, circle (or sphere), and tube forms in the presence of RNA. Image analysis of electron micrographs revealed that tubes were formed by cage-like lattices of CANC proteins surrounding at least two different types of protein-free cage holes. By virtue of a His tag association with nickel-chelating lipids, His-MoCANC proteins also assembled into planar sheets on lipid monolayers, mimicking the membrane-associated immature PrGag protein forms. Membrane-bound His-MoCANC proteins organized into two-dimensional (2D) cage-like lattices that were closely related to the tube forms, and in the presence of both nickel-chelating lipids and RNAs, 2D lattice forms appeared similar to lattices assembled in the absence of RNA. Our observations are consistent with a M-MuLV morphogenesis model in which proteolytic processing of membrane-bound Gag proteins permits CA and NC domains to rearrange from an immature spherical structure to a condensed mature form while maintaining local protein-protein contacts.     

A 3-hydroxy-3-methylglutaryl-CoA synthase-based probe for the discovery of the acyltransferase-less type I polyketide synthases

Acyltransferase (AT)-less type I polyketide synthases (PKSs) produce complex natural products due to the presence of many unique tailoring enzymes. The 3-hydroxy-3-methylglutaryl coenzyme A synthases (HCSs) are responsible for β-alkylation of the growing polyketide intermediates in AT-less type I PKSs. In this study, we discovered a large group of HCSs, closely associated with the characterized and orphan AT-less type I PKSs through in silico genome mining, sequence and genome neighbourhood network analyses. Using HCS-based probes, the survey of 1207 in-house strains and 18 soil samples from different geographic locations revealed the vast diversity of HCS-containing AT-less type I PKSs. The presence of HCSs in many AT-less type I PKSs suggests their co-evolutionary relationship. This study provides a new probe to study the abundance and diversity of AT-less type I PKSs in the environment and microbial strain collections. Our study should inspire future efforts to discover new polyketide natural products from AT-less type I PKSs.     

恒河猴心房利钠多肽的分离、纯化及活性研究

<正> 1983年以来,人们相继从人和大鼠等动物的心房中分离到心房利钠多肽(ANP)。但对非人灵长类动物——恒河猴的ANP了解甚少。由于ANP对机体循环系统的调节起着重要作用,其强大的降压、利钠、利尿的生理功能,在心血管疾病的防治方面具有重要意义。我们曾报导过恒河猴心房肌细胞中存在着大量的ANP样物质,随后对此物质进行了分离、纯化及活性检测,现简报如下。     

Culturable Actinobacteria from the Marine Sponge Hymeniacidon perleve: Isolation and Phylogenetic Diversity by 16S rRNA gene-RFLP Analysis

A total of 106 actinobacteria associated with the marine sponge Hymeniacidon perleve collected from the Yellow Sea, China were isolated using eight different media. The number of species and genera of actinobacteria recovered from the different media varied significantly, underlining the importance of optimizing the isolation conditions. The phylogenetic diversity of the actinobacteria isolates was assessed using 16S rRNA gene amplification–restriction fragment length polymorphism (RFLP) analysis of the 106 strains with different morphologies. The RFLP fingerprinting of selected strains by HhaI-digestion of the 16S rRNA genes resulted in 11 different patterns. The HhaI-RFLP analysis gave good resolution for the identification of the actinobacteria isolates at the genus level. A phylogenetic analysis using 16S rRNA gene sequences revealed that the isolates belonged to seven genera of culturable actinobacteria including Actinoalloteichus, Micromonospora, Nocardia, Nocardiopsis, Pseudonocardia, Rhodococcus, and Streptomyces. The dominant genus was Streptomyces, which represented 74% of the isolates. Three of the strains identified are candidates for new species.