中药对细菌群体感应系统的抑制作用研究进展

细菌的群体感应系统控制着细菌生物膜的形成、毒力因子的表达和耐药性的产生等过程,群体感应抑制剂可在一定程度上减弱细菌的致病性和耐药性,给临床感染性疾病的防治带来福音。中药群体感应抑制剂通过抑制细菌信号分子的合成、促进信号分子的降解以及抑制信号分子与受体蛋白相结合,对细菌群体感应系统起到抑制作用。文章综述了中药对革兰氏阴性细菌和革兰氏阳性细菌群体感应系统的抑制作用,以期为新型抗菌药物的筛选提供新的思路。     

细菌天然群体感应信号分子抑制剂研究进展

长期抗生素滥用导致了多重耐药菌株及其超级细菌的出现,由密度感应系统调控的生物被膜的形成和成熟是造成细菌感染的机制之一。自然界存在的生物活性物质能够淬灭密度感应系统,这些生物活性物质被称为群体感应信号分子抑制剂(quorum sensing inhibitor,QSI)。近年来,群体感应抑制剂成为细菌抗感染药物开发的靶点,有必要对细菌群体感应信号分子抑制剂种类、作用机制进行研究,本文综述了细菌天然群体感应信号分子抑制剂,干扰群体感应系统,从而治疗细菌感染。绝大多数原核生物能够产生群体感应抑制剂,这被认为是安全的。动物、豆类、传统的药用植物、海洋生物均能产生群体感应抑制剂。这些天然抑制剂可能替代传统抗生素,具有广阔的研究和应用前景。     

群体感应分子——法尼醇与白色念珠菌的相互作用

群体感应最早在细菌中发现,近年来也陆续发现存在于真菌中。群体感应中的关键信号分子被称为群体感应分子,是由微生物自身所分泌、感知、响应并作用于其自身,在引起反应的浓度时对其自身没有毒性的一类物质。法尼醇是白色念珠菌的群体感应分子,影响白色念珠菌的耐药性、菌丝形成、黏附力和凋亡;影响白色念珠菌宿主机体的免疫及宿主细胞的凋亡。此外,白色念珠菌对法尼醇具有高于其他真菌的耐受性,但这种机制尚不明确。目前对群体感应分子法尼醇的作用机制缺乏了解,本文就群体感应分子法尼醇与白色念珠菌之间的相互作用展开综述。     

反刍家畜瘤胃微生物群体感应

群体感应(quorum-sensing,QS)是一种微生物细胞间的通讯机制,微生物通过分泌信号分子来感知细胞(群体)密度,并在信号分子达到一定浓度时,通过调节特定基因的表达来调控群体内微生物众多生理生化过程的行为.研究发现群体感应广泛存在于微生物界,并在调控微生物间的共生或竞争中发挥了重要作用.反刍家畜瘤胃适宜的环境(如恒定的温度、pH及充足的养分)为众多微生物的生长提供了良好条件,同时,这些瘤胃微生物在对营养物质进行降解时存在着复杂的共生、竞争关系.目前,研究人员经研究证实反刍家畜瘤胃微生物同样具有群体感应,本文对反刍家畜瘤胃微生物群体感应的研究进展进行了综述,并对今后该领域的研究作出了展望.     

胃肠营养化学感应及其生理效应

胃肠化学感应(chemosensing)是指胃肠道内分泌细胞功能与内脏迷走神经元之间复杂的相互作用。胃肠道内分泌细胞监测到管腔内容物后,释放信号分子,激活神经纤维或其他靶目标,产生生理效应。本文综述了胃肠营养化学感应受体和信号转导途径,阐述了胃肠道内分泌细胞碳水化合物、蛋白质和脂肪的感应机制及其在激素分泌、摄食和黏膜防御调控中的作用。     

胃肠营养化学感应及其生理效应

胃肠化学感应(chemosensing)是指胃肠道内分泌细胞功能与内脏迷走神经元之间复杂的相互作用。胃肠道内分泌细胞监测到管腔内容物后,释放信号分子,激活神经纤维或其他靶目标,产生生理效应。本文综述了胃肠营养化学感应受体和信号转导途径,阐述了胃肠道内分泌细胞碳水化合物、蛋白质和脂肪的感应机制及其在激素分泌、摄食和黏膜防御调控中的作用。     

鱼类mtDNA及其非编码区的研究概况

自从上世纪80年代以来,线粒体DNA一直是分子生物学研究中的一个热点领域,已成为鱼类进化生物学和群体遗传学研究的重要分子遗传标记。文章介绍了鱼类线粒体DNA结构特征及研究方法,重点介绍了鱼类线粒体DNA非编码区结构研究的概况。     

细菌群体感应种类及其信号分子的研究进展

<正>细菌的群体感应(Quorum sensing,QS)效应为存在于细菌中,通过响应细菌细胞的密度变化而调节基因表达的机制。随着细菌细胞数目的增加,细菌通过QS的作用产生、释放类激素分子-自诱导物(Autoinducers,AI)并积聚在细菌细胞的外环境中,细菌就是通过这种被称作AI的信号分子的浓度变化来进行信息交流[1]。AI是随着细菌细胞密度的增大而增大的,当AI积聚达到一定的阈值时,     

黄曲霉次级代谢的分子机制研究进展

黄曲霉是一种常见的霉菌,其次级代谢产物黄曲霉毒素是公认的致癌物质。综述黄曲霉菌次级代谢的分子机制,包括环境反应机制(应激反应途径、群体感应和G蛋白信号通路等),并介绍转录调控单元Velvet Complex的功能和用分子生物技术消除黄曲霉菌毒素对人类危害的可能。     

甜味

动物觅食受化学感应信号驱使,这种信号能检测可用食物源的营养价值。食物经口腔进入胃肠道,在吞咽之前,食物在口腔中按多种化学和物理指标受到检查和辨别。饥饿时,位于口鼻腔的化学感应系统(主要是嗅觉和味觉)感知日粮的养分,并产生     

The impact of quorum sensing on the virulence of Aeromonas hydrophila and Aeromonas salmonicida towards burbot (Lota lota L.) larvae

In this study, the link between quorum sensing in Aeromonas spp. and its virulence towards burbot (Lota lota) was investigated. High mortality occurred in burbot juveniles challenged with Aeromonas salmonicida HN-00, but not in juveniles challenged with Aeromonas hydrophila AH-1N. Meanwhile, both A. hydrophila AH-1N and A. salmonicida HN-00 were virulent towards larvae. The effect of quorum sensing on the virulence of A. hydrophila AH-1N towards burbot larvae was further investigated using quorum sensing mutants (N-(butyryl)-L-homoserine lactone production and receptor mutants). Challenge with these mutants resulted in higher survival of burbot larvae when compared to challenge with the wild type, and the addition of the signal molecule N-butyryl-L-homoserine lactone restored the virulence of the quorum sensing production mutant. Moreover, quorum sensing inhibitors protected the burbot larvae from both Aeromonas strains. Finally, the freshwater micro-algae Chlorella saccharophila and Chlamydomonas reinhardtii, which are able to interfere with quorum sensing, also protected burbot from the pathogens. However, QS interference was unlikely to be the only mechanism. This study revealed that the virulence of Aeromonas spp. towards burbot is regulated by quorum sensing and that quorum sensing inhibitors and micro-algae are promising biocontrol agents.     

Construction and analysis of a Mannheimia haemolytica A1 luxS mutant

Mannheimia haemolytica A1 is the causative agent of bovine pneumonic pasteurellosis, a major cause of sickness, death, and economic loss to the feedlot cattle industry. M. haemolytica A1 produces autoinducer-2 (AI-2) like molecules that are capable of inducing quorum sensing system 2 of Vibrio harveyi. This interspecies quorum sensing system has been shown to regulate the expression of virulence genes in several pathogenic bacteria. The protein central to the production of AI-2 is LuxS. To determine if quorum sensing is involved in the regulation of virulence genes in M. haemolytica A1, a luxS mutant was constructed by replacing luxS with a cat cassette. This mutant was verified by PCR analysis, Southern hybridization, as well as its inability to induce bioluminescence in the V. harveyi reporter strain. RT-PCR analysis showed there was no difference in leukotoxin (lktC) mRNA levels, however there were increased mRNA levels of putative virulence associated genes, transferrin binding protein B (tbpB), adhesin (ahs) and capsule biosynthesis (nmaA). Electron microscopy showed that the level of encapsulation in the mutant is higher than the parent. Additionally, the mutant was slightly more adherent to bovine tracheal cells than the parent. In vitro competition assays showed the mutant out-competed the parent under iron-restricted conditions. However, in a calf challenge, the parent was the dominant isolate recovered.     

Comparative genomics reveals insights into characterization and distribution of quorum sensing-related genes in Shewanella algae from marine environment and clinical sources

Shewanella algae is not only the most commonly reported species in Shewanella human infections but also capable to inhabit a wide variety of habitats. Although there is evidence that quorum sensing is associated with bacterial adaptation to changing environmental conditions, little is known of the quorum sensing system in S. algae. In this study, we conducted the whole genome sequencing of S. algae strains and applied comparative genomics to reveal the core genome. Genes related to the quorum sensing system were identified by integrated bioinformatics analysis. S. algae harbor genes involved in all three main types of autoinducer systems. This study provides insights into the quorum sensing systems in S. algae, which might be valuable in the future study of cell behavior in S. algae.     

铜绿假单胞菌生物膜研究进展

条件致病菌铜绿假单胞菌（PA）是一种能形成生物膜的革兰氏阴性菌,作者综述了PA生物膜形成的生物学机制,包括菌体黏附、胞外多糖Psl和Pel、藻朊酸盐等参与细菌生物膜成熟的过程及群体感应系统调节相关因子表达,从而调控细菌形成生物膜应对不良环境。此外还概括了将生物膜作为靶点开发的药物等生物膜相关的研究进展。生物膜是菌体逃避有害刺激的护盾,研究其结构、形成及致病机理,了解PA产生耐药性的分子机制,对于通过调节生物膜形成或调控生物膜相关因子的表达进而优化PA的抗感染治疗有十分重要的意义。     

Research Progress on Biofilms in Pseudomonas aeruginosa

The opportunistic pathogen Pseudomonas aeruginosa is a gram-negative bacteria which can form biofilms.In this review,we summarized the biology mechanism of biofilms in Pseudomonas aeruginosa,including Pseudomonas aeruginosa adhesion,extracellular polysaccharide Psl and Pel,alginate participated in the biofilm maturation,and quorum sensing systems regulated the formation of biofilm in Pseudomonas aeruginosa,and the drug target on biofilm.The bacterial biofilms protected the bacteria from unsuitable environmental conditions.Through researching the structure and the pathogenesis of Pseudomonas aeruginosa,and its resistance molecular mechanisms,we could adjust or regulate the expression of biofilm-associated factors,optimize the anti-infection treatment in Pseudomonas aeruginosa.     

Flagellin and F4 fimbriae have opposite effects on biofilm formation and quorum sensing in F4ac+ enterotoxigenic Escherichia coli

Bacteria that form biofilms are often highly resistant to antibiotics and are capable of evading the host immune system. To evaluate the role of flagellin and F4 fimbriae on biofilm formation by enterotoxigenic Escherichia coli (ETEC), we deleted the fliC (encoding the major flagellin protein) and/or the faeG (encoding the major subunit of F4 fimbriae) genes from ETEC C83902. Biofilm formation was reduced in the fliC mutant but increased in the faeG mutant, as compared with the wild-type strain. The expression of AI-2 quorum sensing associated genes was regulated in the fliC and faeG mutants, consistent with the biofilm formation of these strains. But, deleting fliC and/or faeG also inhibited AI-2 quorum sensing activity.     

钙磷对酸铝胁迫后紫花苜蓿-根瘤菌体系结瘤固氮的修复效应

本试验采用水培法,以三得利紫花苜蓿和耐酸苜蓿根瘤菌91522为材料,探讨了酸铝胁迫处理苜蓿幼苗1周后,施加Ca²⁺、P对紫花苜蓿-根瘤菌结瘤固氮性能和群体感应的修复/恢复作用。结果表明,酸铝毒害后,Ca²⁺对紫花苜蓿-根瘤菌结瘤过程有显著的修复效应,根瘤菌群体感应、根瘤固氮酶活性显著提高;4 μmol/L P素营养与Ca²⁺存在交互效应,导致苜蓿现瘤时间较未经修复的处理提前14 d,苜蓿结瘤总数提高了247.09%,结瘤率达到90%,根毛变形率由3.33%提高到28.89%。Ca²⁺对结瘤动力学曲线的修复作用主要表现为从开始结瘤起同期结瘤数显著提高。P素对结瘤数影响在Ca²⁺ 5 mmol/L条件下较显著;Ca²⁺对固氮酶活性有显著提高作用,而且5 mmol/L效果优于10 mmol/L,4 μmol/L P素可以进一步提高固氮酶活性。初步认为,补充Ca²⁺和4 μmol/L P可以促进根瘤菌在酸铝胁迫条件下群体感应物的分泌、改善苜蓿根毛对结瘤信号的感知和变形,修复酸铝对苜蓿和根瘤菌的毒害,恢复和提高固氮性能。     

Toll样受体信号传导通路的研究进展

Toll样受体（toll like receptors,TLRs）能识别病原微生物相关分子模式,募集含有Toll/白介素-1受体（TIR）结构域的接头蛋白分子,通过髓样分化蛋白88（MyD88）依赖性信号传导通路或由β-干扰素TIR结构域衔接蛋白（TRIF）依赖性信号传导通路启动信号传导,继而引发特异性的免疫应答。作者就TLRs的结构特征、分布、配体识别、参与信号传导的接头蛋白分子及介导的信号传导通路的最新研究进展进行综述。     

群体感应系统调控细菌生物膜的研究进展

主要介绍了细菌生物膜的概念及其形成过程、细菌群体感应（QS）的概念以及革兰阴性菌的AHL-LuxI/LuxR型QS系统、革兰阳性菌的QS系统、LuxS/AI-2介导的种间QS系统、AI-3/肾上腺素/去甲肾上腺素信息系统4种QS系统的调节机制。就QS系统在细菌中发挥的作用以及对生物膜的调控进行初步阐述,以期为乳酸菌的开发利用和致病菌耐药性的研究提供参考。