Pederin belongs to a group of antitumor compounds found in terrestrial beetles and marine sponges. It is apparently used by some members of the rove beetle Paederus as a chemical defense against predators. A recent cl...Pederin belongs to a group of antitumor compounds found in terrestrial beetles and marine sponges. It is apparently used by some members of the rove beetle Paederus as a chemical defense against predators. A recent cluster analysis of the putative pederin biosynthesis gene （ped） strongly suggests that pederin is produced by bacterial symbionts. This paper reviewed the criteria for proving symbiontic origin of bioactive metabolite, indirect and molecular evidences for pederin bacterial origin, as well as three sets ofped clusters and putative biosynthesis process of pederin.展开更多
There exists a kind of symbiotic bacterium named ＂Candidatus Arsenophonus nilaparvatae＂ in the brown planthopper （BPH）, Nilaparvata lugens. After being filtered and assembled from the BPH genome sequencing project...There exists a kind of symbiotic bacterium named ＂Candidatus Arsenophonus nilaparvatae＂ in the brown planthopper （BPH）, Nilaparvata lugens. After being filtered and assembled from the BPH genome sequencing project, the genome sequence of this bacterial symbiont was obtained. After initial analysis based on the genome, we have found its potential role to synthesize B vitamins for the host. In order to better understand the lifestyle and the genomic changes of this symbiotic bacterium after the symbiotic relationship was established, we further report the characteristics of this draft genome. Compared with several other related bacteria, ＂Candidatus Arsenophonus nilaparvatae＂ has proven to be a facultative endosymbiont at the genomic level. Concurrently, the presence of fimbriae and flagella formation related genes indicates this maternally transmitted endosymbiont is most likely to retain the capacity to invade new hosts. Through further analysis of annotated gene sets, we also find evidence of genome reduction in its secretion system and metabolic pathways. These findings reflect its evolutionary trend to be an obligate one and enable a deeper study of microbe-insect interactions.展开更多
Facultative bacterial endosymbionts in insects have been under intense study during the last years. Endosymbionts can modify the insect＇s phenotype, conferring adap- tive advantages under environmental stress. This s...Facultative bacterial endosymbionts in insects have been under intense study during the last years. Endosymbionts can modify the insect＇s phenotype, conferring adap- tive advantages under environmental stress. This seems particularly relevant for a group of worldwide agricultural aphid pests, because endosymbionts modify key fitness-related traits, including host plant use, protection against natural enemies and heat tolerance. Aimed to understand the role of facultative endosymbionts on the success of introduced aphid pests, the distribution and abundance of 5 facultative endosymbionts （Hamiltonella defensa, Regiella insecticola, Serratia symbiotica, Rickettsia and Spiroplasma） were stud- ied and compared in 4 cereal aphids （Sitobion avenae, Diuraphis noxia, Metopolophium dirhodum and Schizaphis graminium） and in the pea aphid Acyrthosiphon pisum complex from 2 agroclimatic zones in Chile. Overall, infections with faeultative endosymbionts exhibited a highly variable and characteristic pattern depending on the aphid species/host race and geographic zone, which could explain the success of aphid pest populations after their introduction. While S. symbiotica and H. defensa were the most frequent endosym- bionts carried by the A. pisum pea-race and A. pisum alfalfa-race aphids, respectively, the most frequent facultative endosymbiont carried by all cereal aphids was R. insecticola. Interestingly, a highly variable composition of endosymbionts carried by S. avenae was also observed between agroclimatic zones, suggesting that endosymbionts are responding differentially to abiotic variables （temperature and precipitations）. In addition, our findings constitute the first report of bacterial endosymbionts in cereal aphid species not screened before, and also the first report of aphid endosymbionts in Chile.展开更多
The maternally heritable endosymbiont provides many ecosystem functions.Antibiotic elimination of a specific symbiont and establishment of experimental host lines lacking certain symbionts enable the roles of a given ...The maternally heritable endosymbiont provides many ecosystem functions.Antibiotic elimination of a specific symbiont and establishment of experimental host lines lacking certain symbionts enable the roles of a given symbiont to be explored.The whitefly Bemisia tabaci(Gennadius)in China harbors obligate symbiont Portiera infecting each in-dividual,as well as facultative symbionts,such as Hamiltonella,Rickettsia and Cardinium,with co-infections occurring relatively frequently.So far no studies have evaluated the selectivity and efficacy of a specific symbiont elimination using antibiotics in whiteflies co-infected with different symbionts.Furthermore,no success has been achieved in estab-lishing certain symbiont-free B.tabaci lines.In this study,we treated Hamiltonella infected B.tabaci line,Hamiltonella-Rickettsia-co infected line and Hamiltonella-Cardinium co-infected line by feeding B.tabaci adults with cotton plants cultured in water containing ri-fampicin,ampicillin or a mixture of them,aiming to selectively curing symbiont infections and establishing stable symbiont-free lines.We found ampicillin selectively eliminated Cardinium without afecting Portiera,Hamiltonella and Rickettsia,although they coex-isted in the same host body.Meanwhile,all of the symbionts considered in our study can be removed by rifampicin.The reduction of facultative symbionts occurred at a much quicker pace than obligate symbiont Portiera during rifampicin treatment.Also,we measured the stability of symbiont elimination in whitefly successive generations and established Rickettsia-infected and Cardinium-infected lines which are absent in natural populations.Our results provide new protocols for selective elimination of symbionts co-existing in a host and establishment of different symbiont-infected host lines.展开更多
Bemisia tabaci-transmitted geminiviruses are one of the major threats on cassava and vegetable crops in Africa. However, to date, few studies are available on the diversity orB. tabaci and their associated endosymbion...Bemisia tabaci-transmitted geminiviruses are one of the major threats on cassava and vegetable crops in Africa. However, to date, few studies are available on the diversity orB. tabaci and their associated endosymbionts in Africa. More than 28 species have been described in the complex ofB. tabaci cryptic species; among them, 2 are invasive pests worldwide： MED and MEAM1. In order to assess the species diversity orB. tabaci in vegetable crops in Senegal, several samplings in different localities, hosts and seasons were collected and analyzed with nuclear （microsatellite） and mitochondrial （COI） markers. The bacterial endosymbiont community was also studied for each sample. Two species were detected： MED Q1 and MEAM1 B. Patterns of MED Q1 （dominance on most of the samples and sites, highest nuclear and mitochondrial diversity and broader secondary endosymbiont community： Hamiltonella, Cardinium, Wolbachia and Rickettsia）, point toward a predominant resident begomovirus vector group for MED Q 1 on market gardening crops. Furthermore, the lower prevalence of the second species MEAM1 B, its lower nuclear and mitochondrial diversity and a narrower secondary endosymbiont community （Hamiltonella/Rickettsia）, indicate that this genetic group is exotic and results from a recent invasion in this area.展开更多
Bacterial endosymbionts of sap-sucking insects provide their host with a num- ber of beneficial qualities,including the supply of nutrition,defense against parasitoids, and protection from heat stress.Damage to these ...Bacterial endosymbionts of sap-sucking insects provide their host with a num- ber of beneficial qualities,including the supply of nutrition,defense against parasitoids, and protection from heat stress.Damage to these bacterial associates can therefore have a negative impact on the fitness of their insect host.We evaluated observational and experi- mental factors regarding the normative hemlock woolly adelgid (Adelges tsugae Annand) (Hemiptera:Adelgidae)to help understand the roles of its three recently identified symbionts,including under heat stress conditions.The prevalence of A.tsugae's facultafive symbiont (Serratia symbiotica)was examined at different spatial scales to determine how variable infection rates are for this symbiont.There was no significant difference found in infection rates between adelgids on a tree,within a plot,or within a state.However, significantly more adelgids in Georgia (95%)had S.symbiotica compared to those in New York (68%).Microsatellite genotyping of the adelgids found that this difference was most likely not the result of a second introduction ofA.tsugae into eastern North America.Comparison orS.symbiotica proportions between first and fourth instars showed that symbiont absence did not affect the ability ofA.tsugae to survive aestivation.Evaluations of sym- biont densities within each adelgid found that when S.symbiotica was absent,the density of obligate symbionts was significantly higher.Exposure to heat stress (32.5℃)was not consistently correlated with changes in symbiont densities over a 4-d period.Overall,we have shown that symbiont prevalence and densities vary within the broad population of A.tsugae in eastern North America,with potentially significant effects upon the ecology of this important pest.展开更多
Methanogenic endosymbionts are the only known intracellular archaeans and are especially common in anaerobic ciliated protists.Studies on the evolution of associations between anaerobic ciliates and their methanogenic...Methanogenic endosymbionts are the only known intracellular archaeans and are especially common in anaerobic ciliated protists.Studies on the evolution of associations between anaerobic ciliates and their methanogenic endosymbionts offer an excellent opportunity to broaden our knowledge about symbiosis theory and adaptation of eukaryotes to anoxic environments.Here,the diversity of methanogenic endosymbionts was analyzed with the addition of nine anaerobic ciliate populations that were newly studied by various methods.Results showed that diverse anaerobic ciliates host methanogenic endosymbionts that are limited to a few genera in orders Methanomicrobiales,Methanobacteriales,and Methanosarcinales.For the first time,anaerobic ciliates of the classes Muranotrichea and Prostomatea were found to host methanogenic endosymbionts.Distinct origins of endosymbiosis were revealed for classes Armophorea and Plagiopylea.We posit that armophoreans and plagiopyleans might have harbored Methanoregula(order Methanomicrobiales)and Methanocorpusculum(order Metha-nomicrobiales),respectively,as methanogenic endosymbionts at the beginning of their evolution.Subsequently,independent endosymbiont replacement events occurred in methanogen-ciliate associations,probably due to ecological transitions,species radiation of ciliate hosts,and vertical transmission bottlenecks of endosymbionts.Our results shed light on the evolution of associations between anaerobic ciliates and methanogens,and identifies the necessary preconditions for illustrating mecha-nisms by which endosymbioses between these partners were established.展开更多
基金supported by the National Natural Science Foundation of China (30871631)the Natural Science Foundation of Chongqing, China(2007BB1364)
文摘Pederin belongs to a group of antitumor compounds found in terrestrial beetles and marine sponges. It is apparently used by some members of the rove beetle Paederus as a chemical defense against predators. A recent cluster analysis of the putative pederin biosynthesis gene （ped） strongly suggests that pederin is produced by bacterial symbionts. This paper reviewed the criteria for proving symbiontic origin of bioactive metabolite, indirect and molecular evidences for pederin bacterial origin, as well as three sets ofped clusters and putative biosynthesis process of pederin.
基金Acknowledgments This work was supported by grants from the National Natural Science Foundation of China （31272374 and 31070136） and the National Basic Research Program of China （973 Program, No. 2010CB 126205）.
文摘There exists a kind of symbiotic bacterium named ＂Candidatus Arsenophonus nilaparvatae＂ in the brown planthopper （BPH）, Nilaparvata lugens. After being filtered and assembled from the BPH genome sequencing project, the genome sequence of this bacterial symbiont was obtained. After initial analysis based on the genome, we have found its potential role to synthesize B vitamins for the host. In order to better understand the lifestyle and the genomic changes of this symbiotic bacterium after the symbiotic relationship was established, we further report the characteristics of this draft genome. Compared with several other related bacteria, ＂Candidatus Arsenophonus nilaparvatae＂ has proven to be a facultative endosymbiont at the genomic level. Concurrently, the presence of fimbriae and flagella formation related genes indicates this maternally transmitted endosymbiont is most likely to retain the capacity to invade new hosts. Through further analysis of annotated gene sets, we also find evidence of genome reduction in its secretion system and metabolic pathways. These findings reflect its evolutionary trend to be an obligate one and enable a deeper study of microbe-insect interactions.
文摘Facultative bacterial endosymbionts in insects have been under intense study during the last years. Endosymbionts can modify the insect＇s phenotype, conferring adap- tive advantages under environmental stress. This seems particularly relevant for a group of worldwide agricultural aphid pests, because endosymbionts modify key fitness-related traits, including host plant use, protection against natural enemies and heat tolerance. Aimed to understand the role of facultative endosymbionts on the success of introduced aphid pests, the distribution and abundance of 5 facultative endosymbionts （Hamiltonella defensa, Regiella insecticola, Serratia symbiotica, Rickettsia and Spiroplasma） were stud- ied and compared in 4 cereal aphids （Sitobion avenae, Diuraphis noxia, Metopolophium dirhodum and Schizaphis graminium） and in the pea aphid Acyrthosiphon pisum complex from 2 agroclimatic zones in Chile. Overall, infections with faeultative endosymbionts exhibited a highly variable and characteristic pattern depending on the aphid species/host race and geographic zone, which could explain the success of aphid pest populations after their introduction. While S. symbiotica and H. defensa were the most frequent endosym- bionts carried by the A. pisum pea-race and A. pisum alfalfa-race aphids, respectively, the most frequent facultative endosymbiont carried by all cereal aphids was R. insecticola. Interestingly, a highly variable composition of endosymbionts carried by S. avenae was also observed between agroclimatic zones, suggesting that endosymbionts are responding differentially to abiotic variables （temperature and precipitations）. In addition, our findings constitute the first report of bacterial endosymbionts in cereal aphid species not screened before, and also the first report of aphid endosymbionts in Chile.
基金We thank Kai-Li Zhang of Institute of Plant Protection,Jiangsu Academy of Agricultural Sciences for help with the collection of B.tabaci populations.This study was supported by the National Natural Science Foundation of China(31701797)the Natural Science Foundation of Jiangsu Province,China(BK20170598)the Key Re-search and Development Program of Jiangsu Province,China(BE2010342).
文摘The maternally heritable endosymbiont provides many ecosystem functions.Antibiotic elimination of a specific symbiont and establishment of experimental host lines lacking certain symbionts enable the roles of a given symbiont to be explored.The whitefly Bemisia tabaci(Gennadius)in China harbors obligate symbiont Portiera infecting each in-dividual,as well as facultative symbionts,such as Hamiltonella,Rickettsia and Cardinium,with co-infections occurring relatively frequently.So far no studies have evaluated the selectivity and efficacy of a specific symbiont elimination using antibiotics in whiteflies co-infected with different symbionts.Furthermore,no success has been achieved in estab-lishing certain symbiont-free B.tabaci lines.In this study,we treated Hamiltonella infected B.tabaci line,Hamiltonella-Rickettsia-co infected line and Hamiltonella-Cardinium co-infected line by feeding B.tabaci adults with cotton plants cultured in water containing ri-fampicin,ampicillin or a mixture of them,aiming to selectively curing symbiont infections and establishing stable symbiont-free lines.We found ampicillin selectively eliminated Cardinium without afecting Portiera,Hamiltonella and Rickettsia,although they coex-isted in the same host body.Meanwhile,all of the symbionts considered in our study can be removed by rifampicin.The reduction of facultative symbionts occurred at a much quicker pace than obligate symbiont Portiera during rifampicin treatment.Also,we measured the stability of symbiont elimination in whitefly successive generations and established Rickettsia-infected and Cardinium-infected lines which are absent in natural populations.Our results provide new protocols for selective elimination of symbionts co-existing in a host and establishment of different symbiont-infected host lines.
文摘Bemisia tabaci-transmitted geminiviruses are one of the major threats on cassava and vegetable crops in Africa. However, to date, few studies are available on the diversity orB. tabaci and their associated endosymbionts in Africa. More than 28 species have been described in the complex ofB. tabaci cryptic species; among them, 2 are invasive pests worldwide： MED and MEAM1. In order to assess the species diversity orB. tabaci in vegetable crops in Senegal, several samplings in different localities, hosts and seasons were collected and analyzed with nuclear （microsatellite） and mitochondrial （COI） markers. The bacterial endosymbiont community was also studied for each sample. Two species were detected： MED Q1 and MEAM1 B. Patterns of MED Q1 （dominance on most of the samples and sites, highest nuclear and mitochondrial diversity and broader secondary endosymbiont community： Hamiltonella, Cardinium, Wolbachia and Rickettsia）, point toward a predominant resident begomovirus vector group for MED Q 1 on market gardening crops. Furthermore, the lower prevalence of the second species MEAM1 B, its lower nuclear and mitochondrial diversity and a narrower secondary endosymbiont community （Hamiltonella/Rickettsia）, indicate that this genetic group is exotic and results from a recent invasion in this area.
文摘Bacterial endosymbionts of sap-sucking insects provide their host with a num- ber of beneficial qualities,including the supply of nutrition,defense against parasitoids, and protection from heat stress.Damage to these bacterial associates can therefore have a negative impact on the fitness of their insect host.We evaluated observational and experi- mental factors regarding the normative hemlock woolly adelgid (Adelges tsugae Annand) (Hemiptera:Adelgidae)to help understand the roles of its three recently identified symbionts,including under heat stress conditions.The prevalence of A.tsugae's facultafive symbiont (Serratia symbiotica)was examined at different spatial scales to determine how variable infection rates are for this symbiont.There was no significant difference found in infection rates between adelgids on a tree,within a plot,or within a state.However, significantly more adelgids in Georgia (95%)had S.symbiotica compared to those in New York (68%).Microsatellite genotyping of the adelgids found that this difference was most likely not the result of a second introduction ofA.tsugae into eastern North America.Comparison orS.symbiotica proportions between first and fourth instars showed that symbiont absence did not affect the ability ofA.tsugae to survive aestivation.Evaluations of sym- biont densities within each adelgid found that when S.symbiotica was absent,the density of obligate symbionts was significantly higher.Exposure to heat stress (32.5℃)was not consistently correlated with changes in symbiont densities over a 4-d period.Overall,we have shown that symbiont prevalence and densities vary within the broad population of A.tsugae in eastern North America,with potentially significant effects upon the ecology of this important pest.
基金supported by the National Natural Science Foundation of China(32370471,32070406)Basic and Applied Basic Research Founda-tion of Guangdong Province(2024A1515011110)the Project(No.RSP2025R7)of King Saud University,Saudi Arabia.
文摘Methanogenic endosymbionts are the only known intracellular archaeans and are especially common in anaerobic ciliated protists.Studies on the evolution of associations between anaerobic ciliates and their methanogenic endosymbionts offer an excellent opportunity to broaden our knowledge about symbiosis theory and adaptation of eukaryotes to anoxic environments.Here,the diversity of methanogenic endosymbionts was analyzed with the addition of nine anaerobic ciliate populations that were newly studied by various methods.Results showed that diverse anaerobic ciliates host methanogenic endosymbionts that are limited to a few genera in orders Methanomicrobiales,Methanobacteriales,and Methanosarcinales.For the first time,anaerobic ciliates of the classes Muranotrichea and Prostomatea were found to host methanogenic endosymbionts.Distinct origins of endosymbiosis were revealed for classes Armophorea and Plagiopylea.We posit that armophoreans and plagiopyleans might have harbored Methanoregula(order Methanomicrobiales)and Methanocorpusculum(order Metha-nomicrobiales),respectively,as methanogenic endosymbionts at the beginning of their evolution.Subsequently,independent endosymbiont replacement events occurred in methanogen-ciliate associations,probably due to ecological transitions,species radiation of ciliate hosts,and vertical transmission bottlenecks of endosymbionts.Our results shed light on the evolution of associations between anaerobic ciliates and methanogens,and identifies the necessary preconditions for illustrating mecha-nisms by which endosymbioses between these partners were established.
文摘【目的】探明不同地理种群的柑橘木虱Diaphorina citri Kuwayama和柑橘粉虱Dialeurodes citri Ashmead体内昆虫内共生菌的种类及其感染率,并以Wolbachia共生菌为代表,对其系统发育关系进行分析,为今后自共生菌角度研发柑橘木虱和柑橘粉虱的新型防控技术奠定基础。【方法】以16S r DNA、23S r DNA以及wsp为目标基因,利用PCR技术检测采自于广州、湛江、南宁、桂林、厦门的柑橘木虱以及采自广州的柑橘粉虱体内共生菌的种类及其感染率;利用多位点序列分型(MLST)技术和MEGA 5.0软件对不同昆虫样本中的Wolbachia进行系统发育关系分析。【结果】本研究采集的柑橘木虱和柑橘粉虱均含有原生共生菌Portiera和次生共生菌Wolbachia、Cardinium、Rickettsia,但该3种次生共生菌在不同木虱与粉虱种群的感染率有所不同;Arsenophonus只在广州和湛江种群的柑橘木虱中检出。基于wsp基因及MLST基因序列的Wolbachia系统发育分析表明,华南地区柑橘木虱和柑橘粉虱体内的Wolbachia均属于Wolbachia的B大组Con亚组。【结论】不同地理种群的柑橘木虱与柑橘粉虱体内感染的共生菌种类及其感染率不同;Wolabchia共生菌与柑橘木虱寄主不存在协同进化关系,在同一采集点存在Wolbachia通过柑橘寄主在柑橘木虱之间、柑橘木虱与柑橘粉虱之间水平传播的可能性。
