昆虫内共生菌研究概况

内共生菌与昆虫形成互惠共生关系,在宿主昆虫的生长、生殖、传播植物病害以及探讨生命起源与进化等等方面都有很重要的意义。从昆虫内共生菌的特点、内共生菌在昆虫体内的分布、对昆虫的影响、获得少或缺内共生菌的方法及其研究内共生菌的潜在意义等方面进行了综述。     

鳞翅目昆虫内共生菌研究进展

内共生菌(endosymbionts)与其昆虫宿主的共生关系是普遍存在的,它们彼此相互依赖、相互影响、协同进化.近年来,关于昆虫内共生菌的研究多以半翅目(Hemiptera)和双翅目(Diptera)昆虫为主,但数量不断增加的研究表明鳞翅目(Lepidoptera)昆虫与其体内共生菌的互作模式和机制也正在受到越来越多的...     

昆虫内共生菌及其功能研究进展

昆虫内共生菌与宿主之间的互作关系已逐渐成为昆虫学的研究热点之一。昆虫内共生菌具有协助宿主营养代谢、 逃避天敌攻击和增强抗药性等功能： 通过协助宿主营养代谢, 提供食物中缺乏的营养物质来弥补食物中营养物质的不足; 分泌抗菌肽、 毒素等物质以增强对外源寄生物等的防御能力, 抑制对宿主的不利影响; 同时, 也可以增强宿主抗逆性, 调控植物生理反应, 抑制植物对宿主的不利影响; 利用对抗逆性基因精确的表达调控来增强宿主抗药性等。因此, 内共生菌介导的宿主生物学性状的改变, 扩大了宿主昆虫的生态位, 成为昆虫生长发育过程中的重要调控因子。目前, 昆虫内共生菌的功能往往是通过研究宿主感染共生菌前后性状的变化而证实。近几年, 转录组学、 蛋白质组学、 基因组学等技术的进步, 促进了内共生菌与宿主昆虫共生机制研究的发展。通过研究内共生菌及其功能基因在昆虫种群动态中的作用, 特别是内共生菌感染对宿主生殖、 存活、 适应环境能力的影响, 将有利于揭示内共生菌与宿主的共生机制, 并最终为开发新的防控技术提供理论依据。本文针对昆虫内共生菌的功能进行了综述, 并对日后的研究方向进行了展望, 提供了研究昆虫内共生菌与宿主互作关系的方法及建议。     

昆虫内共生菌及其传病毒相关GroEL蛋白

昆虫传播的植物病毒种类多、危害大,其传病毒的能力与昆虫体内共生菌产生的GroEL蛋白关系密切,该蛋白是分子伴侣hsp60家族的成员,对病毒进入昆虫血体腔免遭破坏起着保护作用,也与昆虫传病毒的专一性有关。本对昆虫内共生菌及其产生的GroEL进行了综述,并分析了研究内共生菌及其产生的蛋白质的科学意义与发展趋势,为植物病毒病的防治研究提供了新的思路。     

昆虫内共生菌研究概况*

内共生菌与昆虫形成互惠共生关系,在宿主昆虫的生长、生殖、传播植物病害以及探讨生命起源与进化等等方面都有很重要的意义。从昆虫内共生菌的特点、内共生菌在昆虫体内的分布、对昆虫的影响、获得少或缺内共生菌的方法及其研究内共生菌的潜在意义等方面进行了综述。     

昆虫体外共生菌研究进展

昆虫体外共生菌是指能在体外与宿主发生互利共生关系的微生物。体外共生菌虽然不如肠道微生物那样普遍存在于昆虫中,但也在宿主生长发育过程中扮演着重要的角色。昆虫体外共生菌一般寄生于昆虫体表或体内特异器官(如储菌器),在特定时期转移到植物组织中。体外共生菌产生的挥发物能作为宿主定位寄主植物的信号物质,能为宿主提供生长发育所需的营养物质,还参与了宿主体外免疫。对昆虫体外共生菌的研究,不仅能进一步揭示昆虫与微生物之间的互作关系,丰富昆虫共生菌的研究,还能从共生菌的角度探索害虫引诱剂和昆虫免疫豁免机制。本文对昆虫体外共生菌寄生方式、传播途径、对宿主的影响等研究成果进行了综述,旨在为害虫综合防控提供新思路。     

防御素在免疫中的作用

哺乳动物的防御素是在体内形成的一种小分子杭菌性阳离子肽,是天然免疫中的一种类似抗生素的效应物质。防御素利用树突细胞和T细胞上的趋化因子受体,在微生物侵入后的获得性免疫调节上超重要作用。它也有一定的免疫佐剂活性。本文叙述了各种具有抗菌活性的防御素或抗菌肽的各项免疫活性。     

共生菌在昆虫宿主抵抗病原菌侵染中的作用

昆虫共生菌与宿主的互作关系现已成为昆虫学的研究热点之一。昆虫共生菌不仅能够为宿主的生长发育提供营养物质;还可合成很多活性物质参与调控宿主的生态适应性、抗逆性、多样性形成以及生殖、交配行为等。微生物类杀虫剂虽应用广泛;但由于其代谢产物的毒性以及在田间的长期应用;逐渐在害虫中产生了不同程度的抗性;这与害虫体内共生菌密切相关。本文主要阐述了昆虫共生菌介导宿主在抵御逆境胁迫中的抗性形成;重点归纳了昆虫共生菌协助宿主在抵抗白僵菌Beauveria、绿僵菌Metarhizium、新蚜虫疠霉Pandora neoaphidis以及苏云金芽胞杆菌Bacillus thuringiensis(Bt)等生防真（细）菌侵染中的作用;还深入解析了共生菌对外来病原物侵染宿主的防御机制。现有研究表明;抵御外源病菌侵染的共生菌主要分布于昆虫的表皮、触角腺和肠道等器官或组织中;泛菌Pantoea、假单胞菌Pseudomonas、沃尔巴克氏菌Wolbachia、弗氏柠檬酸杆菌Citrobacter freundii和杀雄菌Arsenophonus等共生菌在协助宿主对抗病原侵染中的表现较为突出;对多种昆虫宿主具有保护作用;此外;这些共生菌主要通过与外源菌竞争营养、分泌抗菌物质和调节免疫系统3条途径来提高昆虫对病原菌的抵抗力。本文为深入解析病原微生物-昆虫-共生菌的之间的互作关系提供了新的思路;也为开发基于共生关系调控的害虫生物防治策略提供了重要参考。     

昆虫免疫防御系统的限制因素

本文主要针对昆虫对寄生物的免疫防御并从进化生态学的角度采阐述昆虫防御系统所存在的一些限制因素,如识别抗原失败、免疫特异性、防御代价、自体免疫、性别、资源利用率和寄生物的干扰等,而这些局限使得昆虫的免疫防御受到不同（自发或诱导的、广泛或具体的）免疫反应的影响。从而限制其持续的免疫防御。     

Pathogen effectors: What do they do at plasmodesmata?

Plants perceive an assortment of external cues during their life cycle, including abiotic and biotic stressors. Biotic stress from a variety of pathogens, including viruses, oomycetes, fungi, and bacteria, is considered to be a substantial factor hindering plant growth and development. To hijack the host cell's defence machinery, plant pathogens have evolved sophisticated attack strategies mediated by numerous effector proteins. Several studies have indicated that plasmodesmata (PD), symplasmic pores that facilitate cell-to-cell communication between a cell and neighbouring cells, are one of the targets of pathogen effectors. However, in contrast to plant-pathogenic viruses, reports of fungal- and bacterial-encoded effectors that localize to and exploit PD are limited. Surprisingly, a recent study of PD-associated bacterial effectors has shown that a number of bacterial effectors undergo cell-to-cell movement via PD. Here we summarize and highlight recent advances in the study of PD-associated fungal/oomycete/bacterial effectors. We also discuss how pathogen effectors interfere with host defence mechanisms in the context of PD regulation.     

Effect of Japanese Paramecium bursaria extract on photosynthetic carbon fixation of symbiotic algae

To investigate the relationship between the Japanese Paramecium bursaria host and its symbiont, we studied the effect of a host cell-free extract on carbon fixation and photosynthate release of the symbiont. The host extract enhanced symbiotic algal carbon fixation about 3-fold at an increased concentration; however, release of photosynthate hardly changed. Since the enhancing effect was not affected by elimination of carbon dioxide from the host extract, the existence of a host factor that stimulates algal carbon fixation was made clear. The host factor is a heat-stable, low molecular weight substance. In relation to the pH dependence, the extract improved carbon fixation at acidic and neutral pH and showed almost no effect at pH 9.0. Therefore, the stimulation of carbon fixation by the host factor is unlikely to be caused by intracellular pH change. The extract also improved carbon fixation of several Chlorella species, symbiotic and free-living, and apparently exhibited no species specificity. Therefore, the host seems to regulate the photosynthesis of the symbiont via a specific compound.     

烟粉虱内共生菌 Rickettsia 在植物体内的分布及转移效率初探

【目的】检测 Q 型烟粉虱 Bemisia tabaci （Gennadius）体内 Rickettsia 的感染情况,研究分析Rickettsia 共生菌经烟粉虱传入豇豆植物后的分布、转移效率等。【方法】以 Q 型烟粉虱为实验材料,利用常规 PCR 及荧光原位杂交技术(FISH),检测了烟粉虱体内 Rickettsia 的感染率,以及 Rickettsia 传入豇豆植物体内后的存留情况。【结果】 Q 型烟粉虱可以通过取食将 Rickettsia 传至豇豆植株内;接虫数量与 Rickettsia传入效率及其在取食部位相邻的下部叶片中检测到的起始时间呈负相关;Rickettsia 经烟粉虱取食传入豇豆叶片后,集中分布在叶片的韧皮部筛管中;基于16S rRNA 的系统发育分析结果表明,Q 型烟粉虱体内的Rickettsia 与经取食传入豇豆叶片的 Rickettsia 高度同源。【结论】 Rickettsia 可以通过烟粉虱的取食传入植物体内,并且可以在相邻叶片之间转移传播,Rickettsia 在由寄主昆虫向植株传播过程中高度保守。     

Wood ants use resin to protect themselves against pathogens

Social life is generally associated with an increased exposure to pathogens and parasites, due to factors such as high population density, frequent physical contact and the use of perennial nest sites. However, sociality also permits the evolution of new collective behavioural defences. Wood ants, Formica paralugubris, commonly bring back pieces of solidified coniferous resin to their nest. Many birds and a few mammals also incorporate green plant material into their nests. Collecting plant material rich in volatile compounds might be an efficient way to fight bacteria and fungi. However, no study has demonstrated that this behaviour has a positive effect on survival. Here, we provide the first experimental evidence that animals using plant compounds with antibacterial and antifungal properties survive better when exposed to detrimental micro-organisms. The presence of resin strongly improves the survival of F. paralugubris adults and larvae exposed to the bacteria Pseudomonas fluorescens, and the survival of larvae exposed to the entomopathogenic fungus Metarhizium anisopliae. These results show that wood ants capitalize on the chemical defences which have evolved in plants to collectively protect themselves against pathogens.