High frequency of hypermutable Pseudomonas aeruginosa in cystic fibrosis lung infection

The lungs of cystic fibrosis (CF) patients are chronically infected for years by one or a few lineages of Pseudomonas aeruginosa. These bacterial populations adapt to the highly compartmentalized and anatomically deteriorating lung environment of CF patients, as well as to the challenges of the immune defenses and antibiotic therapy. These selective conditions are precisely those that recent theoretical studies predict for the evolution of mechanisms that augment the rate of variation. Determination of spontaneous mutation rates in 128 P. aeruginosa isolates from 30 CF patients revealed that 36% of the patients were colonized by a hypermutable (mutator) strain that persisted for years in most patients. Mutator strains were not found in 75 non-CF patients acutely infected with P. aeruginosa. This investigation also reveals a link between high mutation rates in vivo and the evolution of antibiotic resistance.     

Specific lipopolysaccharide found in cystic fibrosis airway Pseudomonas aeruginosa

Cystic fibrosis (CF) patients develop chronic airway infections with Pseudomonas aeruginosa (PA). Pseudomonas aeruginosa synthesized lipopolysaccharide (LPS) with a variety of penta- and hexa-acylated lipid A structures under different environmental conditions. CF patient PA synthesized LPS with specific lipid A structures indicating unique recognition of the CF airway environment. CF-specific lipid A forms containing palmitate and aminoarabinose were associated with resistance to cationic antimicrobial peptides and increased inflammatory responses, indicating that they are likely to be involved in airway disease.     

Pseudomonas-Candida interactions: an ecological role for virulence factors

Bacterial-fungal interactions have great environmental, medical, and economic importance, yet few have been well characterized at the molecular level. Here, we describe a pathogenic interaction between Pseudomonas aeruginosa and Candida albicans, two opportunistic pathogens. P. aeruginosa forms a dense biofilm on C. albicans filaments and kills the fungus. In contrast, P. aeruginosa neither binds to nor kills yeast-form C. albicans. Several P. aeruginosa virulence factors that are important in disease are involved in the killing of C. albicans filaments. We propose that many virulence factors studied in the context of human infection may also have a role in bacterial-fungal interactions.     

Altered regulation of airway epithelial cell chloride channels in cystic fibrosis

In many epithelial cells the chloride conductance of the apical membrane increases during the stimulation of electrolyte secretion. Single-channel recordings from human airway epithelial cells showed that beta-adrenergic stimulation evoked apical membrane chloride channel activity, but this response was absent in cells from patients with cystic fibrosis (CF). However, when membrane patches were excised from CF cells into media containing sufficient free calcium (approximately 180 nanomolar), chloride channels were activated. The chloride channels of CF cells were similar to those of normal cells as judged by their current-voltage relations, ion selectivity, and kinetic behavior. These findings demonstrate the presence of chloride channels in the apical membranes of CF airway cells. Their regulation by calcium appears to be intact, but cyclic adenosine monophosphate (cAMP)-dependent control of their activity is defective.     

副溶血性弧菌Ⅲ型分泌系统与Ⅵ型分泌系统的研究进展

副溶血性弧菌(Vibrio parahaemolyticus,VP)是一种常见的革兰氏阴性细菌,主要分布在海洋、海口和河口沉积物中,能够引起人急性肠胃炎、伤口感染和败血症,同时危害水产品养殖业。由该菌引起的食物中毒事件在全世界范围内频繁发生,该菌被认为是微生物性食物中毒的主要病原菌之一。影响副溶血性弧菌致病性的毒力因素包括溶血素、黏附因子、分泌系统等,尤其在分泌系统中,Ⅲ型分泌系统(TypeⅢsecretion systems, T3SS)和Ⅵ型分泌系统(T6SS)与副溶血性弧菌致病性密切相关。T3SS是一种多亚基针状结构,将分泌蛋白通过供体细胞质直接注入受体细胞质;T6SS是一种接触依赖性蛋白分泌装置,将毒素直接注入目标细胞内。通过对Ⅲ型分泌系统和Ⅵ型分泌系统的研究进展进行梳理,从这两种分泌系统的结构出发,并对其功能和调控机制分别进行分析比较,指出了二者在效应蛋白及产生毒素上的不同,找出了二者与副溶血性弧菌定植的关系,以期通过这两者的联系进而深入了解副溶血性弧菌的致病机制,为防治该菌提供科学指导。     

Recognition of host immune activation by Pseudomonas aeruginosa

It is generally reasoned that lethal infections caused by opportunistic pathogens develop permissively by invading a host that is both physiologically stressed and immunologically compromised. However, an alternative hypothesis might be that opportunistic pathogens actively sense alterations in host immune function and respond by enhancing their virulence phenotype. We demonstrate that interferon-gamma binds to an outer membrane protein in Pseudomonas aeruginosa, OprF, resulting in the expression of a quorum-sensing dependent virulence determinant, the PA-I lectin. These observations provide details of the mechanisms by which prokaryotic organisms are directly signaled by immune activation in their eukaryotic host.     

A microdomain for protein secretion in Gram-positive bacteria

Gram-positive bacteria face unique challenges in generating biologically active conformations for their exported proteins because they lack a dedicated compartment for folding secreted polypeptides. We have discovered that protein secretion by way of the general secretory (Sec) pathway in the important human pathogen Streptococcus pyogenes proceeds through a single microdomain. Unlike other mechanisms for asymmetry involving the Sec pathway, proteins destined for secretion are targeted to a single locus distal to either cell pole that has specialized to contain the Sec translocons. This subcellular organization may represent a paradigm for secretion common to other Gram-positive pathogens with profound implications for pathogenesis.     

Type 6 secretion dynamics within and between bacterial cells

The bacterial type 6 secretion system (T6SS) functions as a virulence factor capable of attacking both eukaryotic and prokaryotic target cells by a process that involves protein transport through a contractile bacteriophage tail-like structure. The T6SS apparatus is composed, in part, of an exterior sheath wrapped around an interior tube. Here, we report that in living cells the cytoplasmic adenosine triphosphatase called ClpV specifically recognizes the contracted T6SS sheath structure, causing its disassembly within seconds. ClpV imaging allowed spatial and temporal documentation of cell-cell interactions (termed T6SS dueling) that likely mark the location of repeated T6SS-mediated protein translocation events between bacterial cells.     

沼气发酵残留物对萝卜品质的影响

[目的]研究沼气发酵残留物对萝卜品质的影响。[方法]以萝卜为材料,研究了7个工程沼肥和户用沼气沼肥与化肥混合施用的处理对萝卜品质的影响。[结果]工程沼肥与化肥按1∶1处理的总糖含量最高;沼肥与化肥按1∶2混合施用总酸含量最高;全施化肥区的萝卜粗纤维和粗蛋白含量最高。户用沼气沼肥与化肥按4∶1混合施用萝卜维生素含量最高,比含量最低的全沼肥区高31.4%;沼肥与化肥按1∶4混合施用,萝卜总糖含量最高,全施化肥区最低;沼肥与化肥按1∶2混合施用,萝卜总酸含量最高;沼肥与化肥按4∶1混合施用,萝卜粗纤维和粗蛋白含量最高;沼肥与化肥配比为2∶1时,萝卜粗蛋白含量最低。[结论]沼气发酵残留物可以显著改善萝卜品质。     

Host resistance to lung infection mediated by major vault protein in epithelial cells

The airway epithelium plays an essential role in innate immunity to lung pathogens. Ribonucleoprotein particles primarily composed of major vault protein (MVP) are highly expressed in cells that encounter xenobiotics. However, a clear biologic function for MVP is not established. We report here that MVP is rapidly recruited to lipid rafts when human lung epithelial cells are infected with Pseudomonas aeruginosa, and maximal recruitment is dependent on bacterial binding to the cystic fibrosis transmembrane conductance regulator. MVP was also essential for optimal epithelial cell internalization and clearance of P. aeruginosa. These results suggest that MVP makes a substantial contribution to epithelial cell-mediated resistance to infection.     

地表臭氧胁迫对冬小麦籽粒品质的影响研究

为深入探讨地表臭氧(O3)对冬小麦品质的影响,采用开顶式气室(OTC),设置3个处理组:CK(对照组)、CF100(O3浓度为100nL·L-1)、CF150(O3浓度为150nL·L-1),通过大田试验和实验室分析,开展了O3浓度增加对冬小麦蛋白质及其组分、氨基酸及其组成、淀粉含量等营养品质和加工品质的影响研究。结果表明:①籽粒氨基酸总量依次为CF100>CF150>CK,而人体所需的必需氨基酸总量为CF150>CF100>CK,处理间均差异显著(P<0.05)。②粗蛋白含量随O3浓度的升高而增加,但各组分间变化趋势不同:清蛋白、球蛋白的含量为CF150>CF100>CK,醇溶蛋白、谷蛋白的含量则为CF100>CF150>CK。③淀粉含量随着O3浓度的升高而降低,两者呈显著负相关(P<0.05),与CK相比,CF100、CF150冬小麦淀粉含量分别下降了4.06%和16.61%。可见,O3胁迫能促进籽粒营养品质和加工品质的合成。     

A sorting platform determines the order of protein secretion in bacterial type III systems

Bacterial type III protein secretion systems deliver effector proteins into eukaryotic cells in order to modulate cellular processes. Central to the function of these protein-delivery machines is their ability to recognize and secrete substrates in a defined order. Here, we describe a mechanism by which a type III secretion system from the bacterial enteropathogen Salmonella enterica serovar Typhimurium can sort its substrates before secretion. This mechanism involves a cytoplasmic sorting platform that is sequentially loaded with the appropriate secreted proteins. The sequential loading of this platform, facilitated by customized chaperones, ensures the hierarchy in type III protein secretion. Given the presence of these machines in many important pathogens, these findings can serve as the bases for the development of novel antimicrobial strategies.     

慢性阻塞性肺疾病急性加重患者痰病原菌分布及耐药性分析

目的 分析本院慢性阻塞性肺疾病急性加重期（acute exacerbation of chronic obstructive pulmonary disease,AECOPD）患者痰菌分布及耐药特点,更好的指导早期临床用药。方法 采集2014年8月到2016年7月本院呼吸病房的613例行痰培养的AECOPD患者的临床资料及痰培养结果,分析其痰菌分布及耐药特点。结果 送检痰标本共检出病菌406株,其中革兰阴性菌、真菌、革兰阳性菌各247株（60.8%）、103株（25.4%）、56株（13.8%）,常见的病菌包括铜绿假单胞菌（17.0%）、白假丝酵母菌（12.8%）、金黄色葡萄球菌（9.9%）、鲍氏/溶血不动杆菌（8.1%）、肺炎克雷伯菌（7.9%）、大肠埃希氏菌（6.9%）、嗜麦芽窄食单胞菌（6.9%）。大肠埃希菌及肺炎克雷伯杆菌产超广谱β-内酰胺酶（ESBLs）阳性率分别为71.4%和34.4%,二者对大部分抗生素有不同程度耐药,铜绿假单胞菌、鲍氏/溶血不动杆菌、嗜麦芽窄食单胞菌耐药率均较高。结论 革兰阴性杆菌为AECOPD患者痰培养的主要菌群,总体耐药性高,结合当地病菌分布及耐药特点选用抗菌药物尤为重要。     

Cl- channels in CF: lack of activation by protein kinase C and cAMP-dependent protein kinase

Secretory chloride channels can be activated by adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase in normal airway epithelial cells but not in cells from individuals with cystic fibrosis (CF). In excised, inside-out patches of apical membrane of normal human airway cells and airway cells from three patients with CF, the chloride channels exhibited a characteristic outwardly rectifying current-voltage relation and depolarization-induced activation. Channels from normal tissues were activated by both cAMP-dependent protein kinase and protein kinase C. However, chloride channels from CF patients could not be activated by either kinase. Thus, gating of normal epithelial chloride channels is regulated by both cAMP-dependent protein kinase and protein kinase C, and regulation by both kinases is defective in CF.     

Study of signal transduction factors involved in mycoparasitic response of Trichoderma atroviride

Numerous Trichoderma spp. are mycoparasites and commercially applied as biological control agents against a large number of plant pathogenic fungi. The mycoparasitic interaction is host-specific and several research strategies have been applied to identify the main genes and compounds involved in the antagonist-plant-pathogen three-way interaction. During mycoparasitism, signals from the host fungus are recognised by Trichoderma, stimulating antifungal activities that are accompanied by mo…     

水稻白叶枯病菌致病性分子遗传学基础

 水稻-白叶枯病原菌互作符合基因对基因关系，是研究禾本科植物-病原菌互作的理想模式系统。目前已鉴定和克隆出许多白叶枯病菌致病相关基因。其它革兰氏阴性植物病原细菌致病性分子遗传学和基因组学研究，为揭示水稻白叶枯病菌致病性分子机理提供了丰富的背景知识，其中以发掘TTSS效应分子的研究备受关注。本文将对白叶枯病菌致病性分子机理进行综述，以期为研究水稻-白叶枯病菌互作的功能基因组学提供科学线索。     

犬皮肤化脓性病灶中主要致病菌的调查及药物敏感实验

采集了30份患皮肤化脓病的犬的化脓灶分泌物进行细菌的分离培养和药敏实验。结果分离出溶血性链球菌11株、金黄色葡萄球菌16株、化脓性棒状杆菌1株和绿脓杆菌5株。药敏实验表明:链球菌的敏感药物为卡那霉素等,金黄色葡萄球菌的敏感药物为庆大霉素等,化脓性棒状杆菌的敏感药物为呋喃妥因等,绿脓杆菌的敏感药物为链霉素等。     

Herpesviral protein networks and their interaction with the human proteome

The comprehensive yeast two-hybrid analysis of intraviral protein interactions in two members of the herpesvirus family, Kaposi sarcoma-associated herpesvirus (KSHV) and varicella-zoster virus (VZV), revealed 123 and 173 interactions, respectively. Viral protein interaction networks resemble single, highly coupled modules, whereas cellular networks are organized in separate functional submodules. Predicted and experimentally verified interactions between KSHV and human proteins were used to connect the viral interactome into a prototypical human interactome and to simulate infection. The analysis of the combined system showed that the viral network adopts cellular network features and that protein networks of herpesviruses and possibly other intracellular pathogens have distinguishing topologies.