首次发现扶桑绵粉蚧体内存在沃尔巴克氏体

沃尔巴克氏体(Wolbachia)是广泛分布在节肢动物生殖组织中的一类细胞质遗传的细菌，它们可以调控宿主的生殖活动。利用沃尔巴克氏体wsp基因的1对通用引物(81F，691R)从新入侵我国的扶桑绵粉蚧Phenacoccus solenopsis Tinsley雌成虫的总DNA中扩增到1个550 bp左右的片段，并克隆得到了Wolbachia的wsp基因序列，首次发现了沃尔巴克氏体对扶桑绵粉蚧的感染现象。     

我国麦蚜体内的沃尔巴克氏体(Wolbachia)的检测

沃尔巴克氏体是广泛分布于节肢动物体内的一类共生细菌 ,它们参与多种调控其寄主生殖活动的机制。本研究通过wsp基因的特异性扩增证实了沃尔巴克氏体在麦长管蚜Sitobionavenae(Fabricius)体内的共生。而且在麦长管蚜的两种体色型 (绿色型和红色型 )中都检测到了沃尔巴克氏体的共生。     

鳞翅目昆虫抗病毒免疫反应的研究进展

鳞翅目昆虫种类繁多,对农业生产和人类生活产生重大影响,宿主昆虫与病毒相互关系的研究对于利用病毒杀虫剂进行害虫治理和益虫病毒性疾病的预防具有重要意义.因此,鳞翅目昆虫与病毒的互作研究显得尤为重要,宿主昆虫的免疫系统在抗病毒感染过程中发挥着关键作用,对病毒产生不同程度的免疫反应.本文综述了昆虫围食膜和中肠对病毒入侵的防御作用,病毒进入体腔后昆虫所产生的细胞免疫和体液免疫反应,以及RNAi、细胞的自噬与凋亡、Toll、Imd、JAK-STAT和STING信号通路等相关的抗病毒免疫途径,并对昆虫抗病毒免疫研究的制约因素和未来鳞翅目昆虫抗病毒免疫的研究重点进行了讨论,以期为害虫的生物防治和益虫疾病的防控提供理论依据.     

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。     

首次发现沃尔巴克氏体Wolbachia对我国南亚果实蝇的感染现象

沃尔巴克氏体Wolbachia是广泛分布于节肢动物体生殖组织内的一类共生细菌,泰国等已发现Wolbachia感染南亚果实蝇Bactrocera(Zeugodacus)tau(Walker)的现象。利用沃尔巴克氏体wsp基因的1对通用引物(81F,691R)从我国南亚果实蝇的总DNA中扩增到1段500 bp左右的wsp基因片段,并克隆得到了Wolbachia相关序列,首次发现了沃尔巴克氏体对我国南亚果实蝇的感染现象。     

沃尔巴克氏体在中国三种稻飞虱中的感染

用PCR方法检测了采集于不同地域稻田的3种稻飞虱共生菌沃尔巴克氏体(Wolbachia)的感染,发现灰飞虱Laodelphax striatellus、褐飞虱Nilaparvata lugens、白背飞虱Sogatella furcifera为沃尔巴克氏体所感染。克隆了编码沃尔巴克氏体外膜蛋白质的wsp基因并进行了序列测定。对wsp的RFLP分析证实了这些飞虱为单一沃尔巴克氏体感染。研究了灰飞虱中沃尔巴克氏体所诱导的胞质不相容性及其在不同地域灰飞虱中的分布。还发现能寄生于上述3种飞虱的稻虱红螯蜂也受同种沃尔巴克氏体感染。沃尔巴克氏体可能通过这种寄生蜂在不同昆虫间横向传播。     

刺吸式昆虫次生内共生菌的研究进展

蚜虫作为典型的刺吸式昆虫,需要以取食植物韧皮部汁液来补充营养,几乎所有蚜虫均带有一种能为其提供植物韧皮部缺失营养物质的初生共生菌Buchnera aphidicola。此外,蚜虫还可携带一种或多种次生内共生菌。在众多共生菌—寄主系统中,蚜虫与其所带内共生菌间的互作研究最为透彻。虽然次生内共生菌对寄主的存活和生殖影响并不显著,但其在寄主对环境耐受力、天敌防御能力等方面作用明显。本文在查阅大量蚜虫次生内共生菌相关文献的基础上,着重对蚜虫次生内共生菌的种类及传播规律、次生内共生菌对蚜虫表型的影响、蚜虫次生内共生菌基因组学等方面的研究现状进行综述,以求为刺吸式昆虫次生内共生菌的研究提供参考。     

棉蚜体内感染沃尔巴克氏体（Wolbachia）的分子检测

Wolbachia是存在于节肢动物体内的一类呈母系遗传的细胞内共生细菌 ,这类细菌可以通过卵的细胞质传播并参与调控寄主的生殖活动。通过对Wolbachia外膜蛋白质的wsp基因进行特异性扩增 ,证实了寄生于不同植物的棉蚜 (AphisgossypiiGlover)体内均有感染 ,说明Wolbachia可能广泛存在于棉蚜体内 ,扩增出的Wolbachia目的片段为 5 90bp左右。通过对棉蚜体内感染的Wolbachia的wsp基因序列进行分子检测 ,为进一步研究棉蚜的孤雌生殖与Wolbachia的相关关系等奠定基础。     

昆虫RNA沉默抗病毒机制研究进展

RNA沉默是昆虫用来抵御病毒入侵的一种普遍而又进化保守的防御机制, 而昆虫病毒也会相应地编码沉默抑制子来破坏宿主的防御功能。本文主要结合果蝇的相关研究成果对昆虫RNA沉默抗病毒机制、 RNA沉默抑制子的作用特征及宿主与病毒的共进化关系做一综述。研究表明, 由小干扰RNA (small interfering RNAs, siRNA)介导的RNA干扰在果蝇抗病毒防御机制中发挥重要作用。果蝇中Dicer-2（Dcr-2）, argonaute-2（AGO2）和双链RNA结合蛋白R2D2是siRNA干扰途径中的3个关键组分, 这3个基因的缺失或突变会显著提高果蝇对RNA病毒的感受性。此外, 果蝇中还鉴定了其他与RNA干扰密切相关的基因, 如vasa intronic gene, aubergine, armitage, rm62 和piwi, 它们在抗病毒感染中同样发挥重要作用。果蝇病毒中已鉴定出3种RNA沉默病毒抑制子（viral suppressors of RNAi, VSRs）, 分别为果蝇FHV病毒沉默抑制子FHV-B2、 果蝇C病毒沉默抑制子DCV-1A及果蝇CrPV病毒沉默抑制子CrPV-1A。FHV-B2和DCV-1A通过与dsRNA或siRNA结合抑制RNA沉默, 而CrPV-1A通过与AGO2结合阻止RISC的形成抑制RNA沉默。在漫长的进化过程中, 病毒和宿主相互博弈, 协同进化。昆虫抗病毒沉默途径中的关键组分通过保持持续和快速进化来对抗高度变异的VSRs。     

A Survey of the bacteriophage WO in the endosymbiotic bacteria Wolbachia

Bacteriophages are common viruses infecting prokaryotes. In addition to their deadly effect, phages are also involved in several evolutionary processes of bacteria, such as coding functional proteins potentially beneficial to them, or favoring horizontal gene transfer through transduction. The particular lifestyle of obligatory intracellular bacteria usually protects them from phage infection. However, Wolbachia, an intracellular alpha-proteobacterium, infecting diverse arthropod and nematode species and best known for the reproductive alterations it induces, harbors a phage named WO, which has recently been proven to be lytic. Here, phage infection was checked in 31 Wolbachia strains, which induce 5 different effects in their hosts and infect 25 insect species and 3 nematodes. Only the Wolbachia infecting nematodes and Trichogramma were found devoid of phage infection. All the 25 detected phages were characterized by the DNA sequence of a minor capsid protein gene. Based on all data currently available, phylogenetic analyses show a lack of congruency between Wolbachia or insect and phage WO phylogenies, indicating numerous horizontal transfers of phage among the different Wolbachia strains. The absence of relation between phage phylogeny and the effects induced by Wolbachia suggests that WO is not directly involved in these effects. Implications on phage WO evolution are discussed.     

Two endosymbiotic bacteria, Wolbachia and Arsenophonus, in the brown planthopper Nilaparvata lugens

The brown planthopper Nilaparvata lugens harbors intracellular fungal yeast-like symbionts and endosymbiotic bacteria, with the latter mainly comprising Wolbachia and Arsenophonus. In this study, Wolbachia or Arsenophonus were detected in all 15 brown planthopper populations collected from China and Southeastern Asian countries. Furthermore, Polymerase Chain Reaction (PCR) analysis of the individuals in a population that was infected by both Wolbachia and Arsenophonus showed that each individual was infected by only one of the two symbiotic bacteria. Real-time quantitative PCR showed that both endosymbionts are mainly localized in the mycetocytes of the fat body. Reciprocal crosses between the Wolbachia ⁺ and Arsenophonus ⁺ brown planthopper populations showed that both bacteria were maternally transmitted. Our results showed that the brown planthopper populations are extensively infected by Wolbachia or Arsenophonus, and the two bacteria may be exclusive in each host individual. This finding might be helpful for further studies on the biological functions of the endosymbiotic bacteria and will deepen our understanding of the complicated symbiosis system in this host.     

Wolbachia与昆虫寄主关系研究进展

Wolbachia pipientis是一种广泛存在于节肢动物和线虫生殖组织中的细胞内共生菌,通过母系生殖细胞在寄主种群内垂直传播。据分析,Wolbachia在昆虫中的感染率大约为66%,是昆虫中分布最广泛的胞内共生菌。Wolbachia能够以多种方式调控寄主的生殖行为,包括诱导细胞质不亲和、诱导孤雌生殖、雌性化、杀雄作用等。近10年来,Wolbachia的研究在多个领域都取得了长足进展。本文介绍了Wolbachia的多样性与分布、对寄主生殖行为的影响、基因组结构,以及其与寄主在基因组水平上的相互作用等领域的最新研究成果,并展望了Wolbachia研究的发展趋势。     

我国桃蛀螟四个地理种群感染Wolbachia的研究

Wolbachia是一类广泛分布于节肢动物体内的细胞内共生菌,能参与调控寄主的多种生殖活动.桃蛀螟Conogethes punctiferalis (Guenée)可危害多种粮食作物和经济作物,近年来已成为我国玉米生产的重要害虫之一.本研究对通过对16S rRNA、fts以及wsp基因片断的PCR扩增,对我国桃蛀螟4个地理种群进行了Wolbachia感染检测,并对感染个体中wsp基因片断克隆测序,初步探究了我国桃蛀螟种群中Wolbachia的感染率和感染类群.研究结果表明我国4个桃蛀螟种群中Wolbachia感染率在2.0%～8.0%,平均感染率为4.5%.通过对不同种群感染的Wolbachia中wsp序列比对及系统树构建分析,在桃蛀螟中发现了5种Wolbachia亚型,分别命名为wPun1-wPun5,分属于A组的Uni、Dro亚组,以及B组的Div、Con亚组.此外,本研究在采自河北保定的桃蛀螟种群中发现了Wolbachia的超感染现象.     

Endosymbiotic Wolbachia bacteria as biological control tools of disease vectors and pests

Wolbachia bacteria are common cytoplasmic symbionts of insects, mites and filarial nematodes. They can alter the reproduction of their hosts. The symbiont could be eliminated, transferred or used through genetic alteration to take advantage or remove their possible influences on pests and/or natural enemies. Their extensive effects on reproduction and host fitness have made Wolbachia the subject of growing attention as a potential biocontrol agent. Here, we summarize the relations of Wolbachia in the control of disease vectors and pests. Furthermore, the drawbacks of these bacteria are also discussed.     

Recent changes in phenotype and patterns of host specialization in Wolbachia bacteria

Wolbachia are a genus of bacterial symbionts that are known to manipulate the reproduction of their arthropod hosts, both by distorting the host sex ratio and by inducing cytoplasmic incompatibility. Previous work has suggested that some Wolbachia clades specialize in particular host taxa, but others are diverse. Furthermore, the frequency with which related strains change in phenotype is unknown. We have examined these issues for Wolbachia bacteria from Acraea butterflies, where different interactions are known in different host species. We found that bacteria from Acraea butterflies mostly cluster together in several different clades on the bacterial phylogeny, implying specialization of particular strains on these host taxa. We also observed that bacterial strains with different phenotypic effects on their hosts commonly shared identical gene sequences at two different loci. This suggests both that the phenotypes of the strains have changed recently between sex ratio distortion and cytoplasmic incompatibility, and that host specialization is not related to the bacterial phenotype, as suggested from previous data. We also analysed published data from other arthropod taxa, and found that the Wolbachia infections of the majority of arthropod genera tend to cluster together on the bacterial phylogeny. Therefore, we conclude that Wolbachia is most likely to move horizontally between closely related hosts, perhaps because of a combination of shared vectors for transmission and physiological specialization of the bacteria on those hosts.     

First detection of endosymbiotic bacteria in biting midges Culicoides pulicaris and Culicoides punctatus,important Palaearctic vectors of bluetongue virus

Heritable bacteria have been highlighted as important components of vector biology, acting as required symbionts with an anabolic role, altering competence for disease transmission, and affecting patterns of gene flow by altering cross compatibility. In this paper, we tested eight U.K. species of Culicoides (Diptera: Ceratopogonidae) midge for the presence of five genera of endosymbiotic bacteria: Cardinium (Bacteroidales: Bacteroidaceae); Wolbachia (Rickettsiales: Rickettsiaceae); Spiroplasma (Entomoplasmatales: Spiroplasmataceae); Arsenophonus (Enterobacteriales: Enterobacteriaceae), and Rickettsia (Rickettsiales: Rickettsiaceae). Cardinium spp. were detected in both sexes of Culicoides pulicaris and Culicoides punctatus, two known vectors of bluetongue virus. Cardinium spp. were not detected in any other species, including the Culicoides obsoletus group, the main vector of bluetongue and Schmallenberg viruses in northern Europe. The other endosymbionts were not detected in any Culicoides species. The Cardinium strain detected in U.K. Culicoides species is very closely related to the Candidatus Cardinium hertigii group C, previously identified in Culicoides species in Asia. Further, we infer that the symbiont is not a sex ratio distorter and shows geographic variation in prevalence within a species. Despite its detection in several species of Culicoides that vector arboviruses worldwide, the absence of Cardinium in the C. obsoletus group suggests that infections of these symbionts may not be necessary to the arboviral vector competence of biting midges.     

Wolbachia对赤眼蜂的性别调控机制及生理影响

沃尔巴克氏体(Wolbachia)是广泛分布于节肢动物生殖组织内的一类共生细菌。它们通过共生诱导宿主赤眼蜂的产雌孤雌生殖,在生物防治上具有重要意义。文章概述了Wolbachia在赤眼蜂中的分布状况,对赤眼蜂的性别调控机制,在赤眼蜂种群中的传播及限制因素,以及对赤眼蜂适合度的影响。     

Bacteriophage flux in endosymbionts (Wolbachia): infection frequency, lateral transfer, and recombination rates

The highly specialized genomes of bacterial endosymbionts typically lack one of the major contributors of genomic flux in the free-living microbial world-bacteriophages. This study yields three results that show bacteriophages have, to the contrary, been influential in the genome evolution of the most prevalent bacterial endosymbiont of invertebrates, Wolbachia. First, we show that bacteriophage WO is more widespread in Wolbachia than previously recognized, occurring in at least 89% (35/39) of the sampled genomes. Second, we show through several phylogenetic approaches that bacteriophage WO underwent recent lateral transfers between Wolbachia bacteria that coinfect host cells in the dipteran Drosophila simulans and the hymenopteran Nasonia vitripennis. These two cases, along with a previous report in the lepidopteran Ephestia cautella, support a general mechanism for genetic exchange in endosymbionts--the "intracellular arena" hypothesis--in which genetic material moves horizontally between bacteria that coinfect the same intracellular environment. Third, we show recombination in this bacteriophage; in the region encoding a putative capsid protein, the recombination rate is faster than that of any known recombining genes in the endosymbiont genome. The combination of these three lines of genetic evidence indicates that this bacteriophage is a widespread source of genomic instability in the intracellular bacterium Wolbachia and potentially the invertebrate host. More generally, it is the first bacteriophage implicated in frequent lateral transfer between the genomes of bacterial endosymbionts. Gene transfer by bacteriophages could drive significant evolutionary change in the genomes of intracellular bacteria that are typically considered highly stable and prone to genomic degradation.