细菌群体感应与细菌生物被膜形成之间的关系

由于滥用抗生素,人类致病菌的耐药日益成为全球性的公共卫生难题。据统计,细菌感染80%以上与细菌生物被膜有关。近年来,有关细菌群体感应和细菌生物被膜的形成乃至机理已有报道,但就群体感应与细菌生物被膜的关系却报道较少,而揭示二者之间的关系可能会为解决致病菌耐药问题提供一个全新的思路。本文立足群体感应和细菌生物被膜的形成机制,结合本课题组的阶段性研究内容,拟阐明细菌群体感应与生物被膜形成的关系。     

重金属胁迫下的细菌适应性进化研究进展

细菌进化的本质是碱基突变、基因重排或水平基因转移,在适应性进化过程中,主要受生物和非生物因素的影响,其中重金属胁迫也是细菌适应性进化的主要因素之一.重金属胁迫促使细菌适应性地强化与金属输入和转化有关的代谢途径,而过量的金属则诱导金属积累和外排过程.在重金属胁迫下,基于重金属抗性(HMR)基因和酶蛋白的适应,细菌抗性机制...     

重金属胁迫下的细菌适应性进化研究进展

细菌进化的本质是碱基突变、基因重排或水平基因转移,在适应性进化过程中,主要受生物和非生物因素的影响,其中重金属胁迫也是细菌适应性进化的主要因素之一。重金属胁迫促使细菌适应性地强化与金属输入和转化有关的代谢途径,而过量的金属则诱导金属积累和外排过程。在重金属胁迫下,基于重金属抗性(HMR)基因和酶蛋白的适应,细菌抗性机制亦发生适应性进化,整理和总结了包括隔离机制适应、金属调控蛋白调控机制适应及酶解毒机制适应方面的研究。目前,重金属离子已对环境造成严重污染,威胁人类健康和生态系统的稳定,因此,阐明重金属胁迫下的细菌适应性进化,不仅丰富了细菌进化研究的内容,而且为在复杂环境条件下实现重金属离子污染的微生物的修复提供了理论基础。     

基于微生物模型的合作行为进化研究进展

生物间的合作行为如何在自然选择过程中显示出对欺骗者的优势,一直以来都是进化生物学上的经典问题。实验室构建的具有合作行为的微生物种群是研究这一问题的良好素材。本文综述了几种基于微生物模型的合作行为进化理论,如亲缘选择理论、辛普森悖论、竞争抑制理论、进化博弈理论等,对其中涉及到的微生物模型进行介绍和评价,并展望其研究前景。     

“纳米细菌”与疾病的研究进展

20世纪80年代后期,芬兰科学家Kajander等在进行哺乳动物细胞培养时,用透射电子显微镜扫描检查时发现细胞内存在一种超微结构.1990年他正式将这种原核微生物命名为\"纳米细菌\"(nanobacteria,NB),并申请了专利,后来将其称为\"钙化性纳米颗粒\"(calcifying nanoparticles,CNP).     

细菌信号传导调控元件的合成生物学研究进展

合成生物学的一个重要目标是设计、改造微生物(主要指细菌),使其能够自主执行复杂任务,如合成重要生物基产品(药物、生物燃料等)、疾病治疗以及环境修复等,造福人类社会.要完成这些任务,细菌必须依赖其信号传导系统,根据环境变化作出正确及时的应答.在长期进化过程中,细菌产生了众多不同的信号传导系统,给我们提供了大量宝贵的信号传导调控元件.通过对这些调控元件的合成生物学设计、改造,我们可以给细菌装备全新的信号传导系统,从而使其能够在工业生物技术及生物医学等应用中执行设定任务.     

细菌“活的不可培养状态”的生态意义及研究进展

\"活的不可培养(VBNC)\"状态是细菌在不良条件下的一种生存方式.VBNC状态作为细菌的一种生理状态,对传统微生物学产生了深远的影响.进入VBNC状态的细胞发生了一系列变化,无法继续用常规培养方法检测,在医学健康,环境科学等领域产生了巨大的影响,改进检测方法具有重要的意义.本文介绍了进入VBNC状态细菌在DNA、蛋白质组成等方面发生的变化,复苏过程.同时还介绍了VBNC状态的最新检测方法,最后对VBNC状态未来的研究方法进行了讨论.     

基于微生物视角的“皮-肠”轴与特应性皮炎

特应性皮炎(atopic dermatitis,AD)是一种难治易复发皮肤病,由于病因复杂且患病率逐年增加,该病已经成为公共卫生领域关注的问题。随着高通量测序、元基因组学和代谢组学等技术的应用,发现AD的发生与发展与微生物群落息息相关,“微生物-皮-肠”轴及它们之间的串扰机制也逐渐被验证。“微生物-皮-肠”轴在过敏性皮肤炎症中扮演了重要角色。本文综述了“微生物-皮-肠”轴与AD的关系,及其可能交流的信号分子和潜在途径,重点关注了涉及益生菌、菌群移植和抗菌肽等微生物缓解AD的潜在机制,为靶向微生物群治疗过敏性皮肤炎症提供了一个新的视角。     

细菌“吃”油,采收有道——微生物采油技术大有前景

1954年,美国率先成功地进行了矿场试验,随后在20世纪50年代末期到70年代,前苏联和东欧一些国家、加拿大、澳大利亚及中国也开展了微生物采油研究,并进行了不少矿场试验。微生物采油技术由于1973年的石油危机得以重视并加速了其发展。进入20世纪90年代以后,生物技术和其他边缘科学技术相继应用在采油技术中,微生物采油技术在单一自然菌基础上发展了工程菌,从单纯的实验研究发展到数学模型的建立和数值模拟研究,作用方式也从单井发展到区块。     

珊瑚共生体中“细菌-虫黄藻-宿主”三角关系的通讯交流

“细菌-虫黄藻-珊瑚”是生态系统中一对经典的三角关系,其中包含着复杂的物质流、信息流和能量流,三者的平衡与稳定是维护珊瑚礁生态系统健康的重要保障。过去20年里针对共生体交互关系进行了大量研究,并取得了一些重要成果,明确了“细菌-虫黄藻-宿主”三者之间的物质代谢、营养交换以及与环境的交互关系。然而,基于共生系统的复杂性,一些现象背后的机制仍然未被充分揭示,尤其是共生体之间的通讯交流。信号分子介导的相互作用是珊瑚共生体稳态维持和高效运转的内在驱动力。本文以珊瑚共生体系中化学信号为重点,尝试梳理最新的研究进展,包括细菌与细菌、细菌与珊瑚、细菌与虫黄藻以及虫黄藻与珊瑚之间的通讯方式,重点关注了群体感应信号(QS)、二甲基巯基丙酸盐(DMSP)、糖类信号、脂类信号以及非编码RNA。选择性例举了QS信号介导的微生物协作和竞争、DMSP调节下的细菌和宿主的相互作用,以及环境胁迫下珊瑚和虫黄藻对非编码RNA的响应过程,强调了它们在共生体中的作用模式和生态意义。并对今后的研究重点和可能方向进行了提炼,包括研究维度的扩充、新技术-新方法的应用以及生态模型的构建等,旨在提升对三角关系互作方式的认识,增进对珊瑚共生体的理解,探索基于通讯语言的操纵方式为珊瑚礁生态系统的恢复和保护提供新思路。     

Cooperation,collective action,and the archeology of large‐scale societies

Archeologists investigating the emergence of large‐scale societies in the past have renewed interest in examining the dynamics of cooperation as a means of understanding societal change and organizational variability within human groups over time. Unlike earlier approaches to these issues, which used models designated voluntaristic or managerial, contemporary research articulates more explicitly with frameworks for cooperation and collective action used in other fields, thereby facilitating empirical testing through better definition of the costs, benefits, and social mechanisms associated with success or failure in coordinated group action. Current scholarship is nevertheless bifurcated along lines of epistemology and scale, which is understandable but problematic for forging a broader, more transdisciplinary field of cooperation studies. Here, we point to some areas of potential overlap by reviewing archeological research that places the dynamics of social cooperation and competition in the foreground of the emergence of large‐scale societies, which we define as those having larger populations, greater concentrations of political power, and higher degrees of social inequality. We focus on key issues involving the communal‐resource management of subsistence and other economic goods, as well as the revenue flows that undergird political institutions. Drawing on archeological cases from across the globe, with greater detail from our area of expertise in Mesoamerica, we offer suggestions for strengthening analytical methods and generating more transdisciplinary research programs that address human societies across scalar and temporal spectra.     

Social dilemma in the external immune system of the red flour beetle? It is a matter of time

Sociobiology has revolutionized our understanding of interactions between organisms. Interactions may present a social dilemma where the interests of individual actors do not align with those of the group as a whole. Viewed through a sociobiological lens, nearly all interactions can be described regarding their costs and benefits, and a number of them then resemble a social dilemma. Numerous experimental systems, from bacteria to mammals, have been proposed as models for studying such dilemmas. Here, we make use of the external immune system of the red flour beetle, Tribolium castaneum, to investigate how the experimental duration can affect whether the external secretion comprises a social dilemma or not. Some beetles (secretors) produce a costly quinone‐rich external secretion that inhibits microbial growth in the surrounding environment, providing the secretors with direct personal benefits. However, as the antimicrobial secretion acts in the environment of the beetle, it is potentially also advantageous to other beetles (nonsecretors), who avoid the cost of producing the secretion. We test experimentally if the secretion qualifies as a public good. We find that in the short term, costly quinone secretion can be interpreted as a public good presenting a social dilemma where the presence of secretors increases the fitness of the group. In the long run, the benefit to the group of having more secretors vanishes and becomes detrimental to the group. Therefore, in such seminatural environmental conditions, it turns out that qualifying a trait as social can be a matter of timing.     

Cooperation,clumping and the evolution of multicellularity

The evolution of multicellular organisms represents one of the major evolutionary transitions in the history of life. A potential advantage of forming multicellular clumps is that it provides an efficiency benefit to pre-existing cooperation, such as the production of extracellular ‘public goods’. However, this is complicated by the fact that cooperation could jointly evolve with clumping, and clumping could have multiple consequences for the evolution of cooperation. We model the evolution of clumping and a cooperative public good, showing that (i) when considered separately, both clumping and public goods production gradually increase with increasing genetic relatedness; (ii) in contrast, when the traits evolve jointly, a small increase in relatedness can lead to a major shift in evolutionary outcome—from a non-clumping state with low public goods production to a cooperative clumping state with high values of both traits; (iii) high relatedness makes it easier to get to the cooperative clumping state and (iv) clumping can be inhibited when it increases the number of cells that the benefits of cooperation must be shared with, but promoted when it increases relatedness between those cells. Overall, our results suggest that public goods sharing can facilitate the formation of well-integrated cooperative clumps as a first step in the evolution of multicellularity.     

Generational coexistence and ancestor's inhibition in bacterial populations

Generational coexistence in structured environments raises the possibility of a competition between ancestors and descendents. This type of kin competition, and in particular, the possibility that descendents might actively repress the ancestor's dominance, has been rarely considered in microbial evolutionary ecology. The recent discovery of the phenomenon of stationary-phase contact-dependent inhibition of bacterial ancestor cells by late descendents provides a new theoretical perspective to analyze intrapopulational evolutionary changes. The ancestor's inhibition effect might accelerate such changes, particularly when the descendents have acquired small adaptive advantages that are insufficient to rapidly displace the well-settled ancestors in a complex niche. Besides this effect of triggering selection of small genetic differences, the opportunities for intergenerational coexistence in bacteria, where ancestor's inhibition might occur, are reviewed in this work. A theoretical analysis is provided about the explanatory possibilities of the ancestor's inhibition effect in the controversies about intraspecific (in a large sense, including intrapopulational) genetic diversification, and the discontinuities observed in such processes, giving rise to the emergence of individualities and therefore differential units of selection.