| systematic relationships and cospeciation of bacterial endosymbionts and their carpenter ant host species: proposal of the new taxon candidatus blochmannia gen. nov. | the systematic relationships of intracellular bacteria of 13 camponotus species (carpenter ants) from america and europe were compared to those of their hosts. phylogenetic trees of the bacteria and the ants were based on 16s rdna (rrs) gene sequences and mitochondrial cytochrome oxidase subunit i (coi) gene sequences, respectively. the bacterial endosymbionts of camponotus spp. form a distinct lineage in the y-subclass of the proteobacteria. the taxa most closely related to these bacteria are e ... | 2000 | 11034499 |
| small genome of candidatus blochmannia, the bacterial endosymbiont of camponotus, implies irreversible specialization to an intracellular lifestyle. | blochmannia (candidatus blochmannia gen. nov.) is the primary bacterial endosymbiont of the ant genus camponotus: like other obligate endosymbionts of insects, blochmannia occurs exclusively within eukaryotic cells and has experienced long-term vertical transmission through host lineages. in this study, pfge was used to estimate the genome size of blochmannia as approximately 800 kb, which is significantly smaller than its free-living relatives in the enterobacteria. this small genome implies th ... | 2002 | 12177348 |
| tissue localization of the endosymbiotic bacterium "candidatus blochmannia floridanus" in adults and larvae of the carpenter ant camponotus floridanus. | the distribution of endosymbiotic bacteria in different tissues of queens, males, and workers of the carpenter ant camponotus floridanus was investigated by light and electron microscopy and by in situ hybridization. a large number of bacteria could be detected in bacteriocytes within the midguts of workers, young virgin queens, and males. large amounts of bacteria were also found in the oocytes of workers and queens. in contrast, bacteria were not present in oocyte-associated cells or in the sp ... | 2002 | 12200264 |
| genome evolution in an insect cell: distinct features of an ant-bacterial partnership. | bacteria that live exclusively within eukaryotic host cells include not only well-known pathogens, but also obligate mutualists, many of which occur in diverse insect groups such as aphids, psyllids, tsetse flies, and the ant genus camponotus (buchner, 1965; douglas, 1998; moran and telang, 1998; baumann et al., 2000; moran and baumann, 2000). in contrast to intracellular pathogens, these primary (p) endosymbionts of insects are required for the survival and reproduction of the host, exist withi ... | 2003 | 12700158 |
| the genome sequence of blochmannia floridanus: comparative analysis of reduced genomes. | bacterial symbioses are widespread among insects, probably being one of the key factors of their evolutionary success. we present the complete genome sequence of blochmannia floridanus, the primary endosymbiont of carpenter ants. although these ants feed on a complex diet, this symbiosis very likely has a nutritional basis: blochmannia is able to supply nitrogen and sulfur compounds to the host while it takes advantage of the host metabolic machinery. remarkably, these bacteria lack all known ge ... | 2003 | 12886019 |
| host-symbiont stability and fast evolutionary rates in an ant-bacterium association: cospeciation of camponotus species and their endosymbionts, candidatus blochmannia. | bacterial endosymbionts are widespread across several insect orders and are involved in interactions ranging from obligate mutualism to reproductive parasitism. candidatus blochmannia gen. nov. (blochmannia) is an obligate bacterial associate of camponotus and related ant genera (hymenoptera: formicidae). the occurrence of blochmannia in all camponotus species sampled from field populations and its maternal transmission to host offspring suggest that this bacterium is engaged in a long-term, sta ... | 2004 | 14965905 |
| evolutionary forces in shaping the codon and amino acid usages in blochmannia floridanus. | endosymbiotic relationship has great effect on ecological system. codon and amino acid usages bias of endosymbiotic bacteria blochmannia floridanus (whose host is an ant camponotus floridanus) was investigated using experimentally known genes of this organism. correspondence analysis on rscu values show that there exists only one single explanatory major axis that is linked to the strand specific mutational biases. majority of the genes have a tendency to concentrate on the leading strand, which ... | 2004 | 15214801 |
| replication of the endosymbiotic bacterium blochmannia floridanus is correlated with the developmental and reproductive stages of its ant host. | the dynamics of replication of the intracellular endosymbiotic bacterium blochmannia floridanus was determined during the larval development of its host ant camponotus floridanus by real-time quantitative pcr. the bacteria were found to proliferate during pupation and immediately after the eclosion of the imagines (adult ants). in older workers the number of bacteria present in the midgut bacteriocytes decreased significantly. in contrast, the bacterial population in the ovaries was dependent on ... | 2004 | 15240288 |
| nonhomogeneous model of sequence evolution indicates independent origins of primary endosymbionts within the enterobacteriales (gamma-proteobacteria). | standard methods of phylogenetic reconstruction are based on models that assume homogeneity of nucleotide composition among taxa. however, this assumption is often violated in biological data sets. in this study, we examine possible effects of nucleotide heterogeneity among lineages on the phylogenetic reconstruction of a bacterial group that spans a wide range of genomic nucleotide contents: obligately endosymbiotic bacteria and free-living or commensal species in the gamma-proteobacteria. we f ... | 2005 | 15525700 |
| genome rearrangement distances and gene order phylogeny in gamma-proteobacteria. | genome rearrangements have been studied in 30 gamma-proteobacterial complete genomes by comparing the order of a reduced set of genes on the chromosome. this set included those genes fulfilling several characteristics, the main ones being that an ortholog was present in every genome and that none of them had been acquired by horizontal gene transfer. genome rearrangement distances were estimated based on either the number of breakpoints or the minimal number of inversions separating two genomes. ... | 2005 | 15772379 |
| the roles of positive and negative selection in the molecular evolution of insect endosymbionts. | the evolutionary rate acceleration observed in most endosymbiotic bacteria may be explained by higher mutation rates, changes in selective pressure, and increased fixation of deleterious mutations by genetic drift. here, we explore the forces influencing molecular evolution in blochmannia, an obligate endosymbiont of camponotus and related ant genera. our goals were to compare rates of sequence evolution in blochmannia with related bacteria, to explore variation in the strength and efficacy of n ... | 2005 | 16039807 |
| genome sequence of blochmannia pennsylvanicus indicates parallel evolutionary trends among bacterial mutualists of insects. | the distinct lifestyle of obligately intracellular bacteria can alter fundamental forces that drive and constrain genome change. in this study, sequencing the 792-kb genome of blochmannia pennsylvanicus, an obligate endosymbiont of camponotus pennsylvanicus, enabled us to trace evolutionary changes that occurred in the context of a bacterial-ant association. comparison to the genome of blochmannia floridanus reveals differential loss of genes involved in cofactor biosynthesis, the composition an ... | 2005 | 16077009 |
| analysis of and function predictions for previously conserved hypothetical or putative proteins in blochmannia floridanus. | there is an increasing interest to better understand endosymbiont capabilities in insects both from an ecological point of view and for pest control. blochmannia floridanus provides important nutrients for its host, the ant camponotus, while the bacterium in return is provided with a niche to proliferate. blochmannia floridanus proteins and metabolites are difficult to study due to its endosymbiontic life style; however, its complete genome sequence became recently available. | 2006 | 16401340 |
| genomic comparisons among gamma-proteobacteria. | predicted highly expressed (phx) genes are compared for 16 gamma-proteobacteria and their similarities and differences are interpreted with respect to known or predicted physiological characteristics of the organisms. predicted highly expressed genes often reflect the organism's predominant lifestyle, habitat, nutrition sources and metabolic propensities. this technique allows to predict principal metabolic activities of the microorganisms operating in their natural habitats. among our findings ... | 2006 | 16423015 |
| phloem-sap feeding by animals: problems and solutions. | the incidence of phloem sap feeding by animals appears paradoxical. although phloem sap is nutrient-rich compared with many other plant products and generally lacking in toxins and feeding deterrents, it is consumed as the dominant or sole diet by a very restricted range of animals, exclusively insects of the order hemiptera. these insects display two sets of adaptations. first, linked to the high ratio of non-essential:essential amino acids in phloem sap, these insects contain symbiotic micro-o ... | 2006 | 16449374 |
| tempo and mode of early gene loss in endosymbiotic bacteria from insects. | understanding evolutionary processes that drive genome reduction requires determining the tempo (rate) and the mode (size and types of deletions) of gene losses. in this study, we analysed five endosymbiotic genome sequences of the gamma-proteobacteria (three different buchnera aphidicola strains, wigglesworthia glossinidia, blochmannia floridanus) to test if gene loss could be driven by the selective importance of genes. we used a parsimony method to reconstruct a minimal ancestral genome of in ... | 2006 | 16848891 |
| relevance of the endosymbiosis of blochmannia floridanus and carpenter ants at different stages of the life cycle of the host. | expression of several genes possibly involved in the symbiotic relationship between the obligate intracellular endosymbiont blochmannia floridanus and its ant host camponotus floridanus was investigated at different developmental stages of the host by real-time quantitative pcr. these included a set of genes related to nitrogen metabolism (urec, uref, glna, and speb) as well as genes involved in the synthesis of the aromatic amino acid tyrosine (tyra, aspc, and hisc). the overall transcriptional ... | 2006 | 16957225 |
| from phylogenetics to phylogenomics: the evolutionary relationships of insect endosymbiotic gamma-proteobacteria as a test case. | the increasing availability of complete genome sequences and the development of new, faster methods for phylogenetic reconstruction allow the exploration of the set of evolutionary trees for each gene in the genome of any species. this has led to the development of new phylogenomic methods. here, we have compared different phylogenetic and phylogenomic methods in the analysis of the monophyletic origin of insect endosymbionts from the gamma-proteobacteria, a hotly debated issue with several rece ... | 2007 | 17366133 |
| nutritional upgrading for omnivorous carpenter ants by the endosymbiont blochmannia. | carpenter ants (genus camponotus) are considered to be omnivores. nonetheless, the genome sequence of blochmannia floridanus, the obligate intracellular endosymbiont of camponotus floridanus, suggests a function in nutritional upgrading of host resources by the bacterium. thus, the strongly reduced genome of the endosymbiont retains genes for all subunits of a functional urease, as well as those for biosynthetic pathways for all but one (arginine) of the amino acids essential to the host. | 2007 | 17971224 |
| identification of two inner-membrane proteins required for the transport of lipopolysaccharide to the outer membrane of escherichia coli. | the outer membrane (om) of most gram-negative bacteria contains lipopolysaccharide (lps) in the outer leaflet. lps, or endotoxin, is a molecule of important biological activities. in the host, lps elicits a potent immune response, while in the bacterium, it plays a crucial role by establishing a barrier to limit entry of hydrophobic molecules. before lps is assembled at the om, it must be synthesized at the inner membrane (im) and transported across the aqueous periplasmic compartment. much is k ... | 2008 | 18375759 |
| complete rpob gene sequencing as a suitable supplement to dna-dna hybridization for bacterial species and genus delineation. | dna-dna hybridization (ddh), the gold standard for bacterial species delineation, is a laborious method and the alternative, average nucleotide identity (ani), a genomic sequence-derived parameter, is not applicable to non-sequenced species. a universal cut-off value to delineate bacterial species does not exist, yet a ddh value <70 % and ani <95+/-0.5 % have proved useful in selected examples. we herein compare published values for ddh and ani with sequence similarity of rpob gene sequences ret ... | 2008 | 18676461 |
| endosymbiont gene functions impaired and rescued by polymerase infidelity at poly(a) tracts. | among host-dependent bacteria that have evolved by extreme reductive genome evolution, long-term bacterial endosymbionts of insects have the smallest (160-790 kb) and most a + t-rich (>70%) bacterial genomes known to date. these genomes are riddled with poly(a) tracts, and 5-50% of genes contain tracts of 10 as or more. here, we demonstrate transcriptional slippage at poly(a) tracts within genes of buchnera aphidicola associated with aphids and blochmannia pennsylvanicus associated with ants. se ... | 2008 | 18815381 |
| transcriptional profiling of the endosymbiont blochmannia floridanus during different developmental stages of its holometabolous ant host. | the transcriptome of blochmannia floridanus, the endosymbiont of the carpenter ant camponotus floridanus, is presented during various developmental stages of its holometabolous host by use of a whole-genome dna macroarray. the detected transcription patterns indicate the presence of local transcription units as well as global regulatory mechanisms. yet, the overall regulation scale is very modest, rarely exceeding a factor of three. a large number of genes show differential expression in differe ... | 2009 | 19040455 |
| blochmannia endosymbionts improve colony growth and immune defence in the ant camponotus fellah. | microorganisms are a large and diverse form of life. many of them live in association with large multicellular organisms, developing symbiotic relations with the host and some have even evolved to form obligate endosymbiosis. all carpenter ants (genus camponotus) studied hitherto harbour primary endosymbiotic bacteria of the blochmannia genus. the role of these bacteria in ant nutrition has been demonstrated but the omnivorous diet of these ants lead us to hypothesize that the bacteria might pro ... | 2009 | 19200360 |
| promoter characterization in the at-rich genome of the obligate endosymbiont "candidatus blochmannia floridanus". | the characterization of transcriptional start sites of 14 genes encoded by the extremely at-rich genome of "candidatus blochmannia floridanus" revealed a high degree of conservation with the rpod promoter consensus sequence of the free-living relative escherichia coli. moreover, in agreement with the presence of the alternative heat shock sigma factor rpoh in "ca. blochmannia," typical rpoh-dependent promoters were identified. however, no heat shock response resembling that of e. coli could be d ... | 2009 | 19329646 |
| patterns and rates of nucleotide substitution, insertion and deletion in the endosymbiont of ants blochmannia floridanus. | genome reduction is a general process that has been studied in numerous symbiotic bacteria associated with insects. we investigated the last stages of genome degradation in blochmannia floridanus, a mutualistic bacterial endosymbiont of the ant camponotus floridanus. we determined the tempo (rates of insertion and deletion) and mode (size and number of insertion-deletion events) of the process in the last 200,000 years by analysing a total of 16 intergenic regions in several strains of this endo ... | 2008 | 19378410 |
| remaining flexible in old alliances: functional plasticity in constrained mutualisms. | central to any beneficial interaction is the capacity of partners to detect and respond to significant changes in the other. recent studies of microbial mutualists show their close integration with host development, immune responses, and acclimation to a dynamic external environment. while the significance of microbial players is broadly appreciated, we are just beginning to understand the genetic, ecological, and physiological mechanisms that generate variation in symbiont functions, broadly te ... | 2009 | 19435425 |
| evolutionary convergence and nitrogen metabolism in blattabacterium strain bge, primary endosymbiont of the cockroach blattella germanica. | bacterial endosymbionts of insects play a central role in upgrading the diet of their hosts. in certain cases, such as aphids and tsetse flies, endosymbionts complement the metabolic capacity of hosts living on nutrient-deficient diets, while the bacteria harbored by omnivorous carpenter ants are involved in nitrogen recycling. in this study, we describe the genome sequence and inferred metabolism of blattabacterium strain bge, the primary flavobacteria endosymbiont of the omnivorous german cock ... | 2009 | 19911043 |
| slip into something more functional: selection maintains ancient frameshifts in homopolymeric sequences. | mutational hotspots offer significant sources of genetic variability upon which selection can act. however, with a few notable exceptions, we know little about the dynamics and fitness consequences of mutations in these regions. here, we explore evolutionary forces shaping homopolymeric tracts that are especially vulnerable to slippage errors during replication and transcription. such tracts are typically eliminated by selection from most bacterial sequences, yet persist in genomes of endosymbio ... | 2010 | 19955479 |
| one nutritional symbiosis begat another: phylogenetic evidence that the ant tribe camponotini acquired blochmannia by tending sap-feeding insects. | bacterial endosymbiosis has a recurring significance in the evolution of insects. an estimated 10-20% of insect species depend on bacterial associates for their nutrition and reproductive viability. members of the ant tribe camponotini, the focus of this study, possess a stable, intracellular bacterial mutualist. the bacterium, blochmannia, was first discovered in camponotus and has since been documented in a distinct subgenus of camponotus, colobopsis, and in the related genus polyrhachis. howe ... | 2009 | 20015388 |
| bacteriocyte dynamics during development of a holometabolous insect, the carpenter ant camponotus floridanus. | the carpenter ant camponotus floridanus harbors obligate intracellular mutualistic bacteria (blochmannia floridanus) in specialized cells, the bacteriocytes, intercalated in their midgut tissue. the diffuse distribution of bacteriocytes over the midgut tissue is in contrast to many other insects carrying endosymbionts in specialized tissues which are often connected to the midgut but form a distinct organ, the bacteriome. c. floridanus is a holometabolous insect which undergoes a complete metamo ... | 2010 | 21122115 |
| unprecedented loss of ammonia assimilation capability in a urease-encoding bacterial mutualist. | blochmannia are obligately intracellular bacterial mutualists of ants of the tribe camponotini. blochmannia perform key nutritional functions for the host, including synthesis of several essential amino acids. we used illumina technology to sequence the genome of blochmannia associated with camponotus vafer. | 2010 | 21126349 |
| immune response of the ant camponotus floridanus against pathogens and its obligate mutualistic endosymbiont. | numerous insect species harbor mutualistic endosymbionts that play a role in nutrient cycling or confer other fitness benefits to their hosts. insect hosts face the problem of having to maintain such mutualistic bacteria while staging an immune response towards pathogens upon infection. in addition, hosts may regulate the number of endosymbionts present in their tissues via the innate immune system. camponotus floridanus ants harbor the obligate endosymbiont blochmannia floridanus in specialized ... | 2011 | 21440063 |
| Blochmannia endosymbionts and their host, the ant Camponotus fellah: cuticular hydrocarbons and melanization. | Carpenter ants (genus Camponotus) have mutualistic, endosymbiotic bacteria of the genus Blochmannia whose main contribution to their hosts is alimentary. It was also recently demonstrated that they play a role in improving immune function as well. In this study, we show that treatment with an antibiotic produces a physiological response inducing an increase in both the quantity of cuticular hydrocarbons and in the melanization of the cuticle probably due to a nutritive and immunological deficit. ... | 2011 | 21943523 |
| reduced selective constraint in endosymbionts: elevation in radical amino acid replacements occurs genome-wide. | as predicted by the nearly neutral model of evolution, numerous studies have shown that reduced n(e) accelerates the accumulation of slightly deleterious changes under genetic drift. while such studies have mostly focused on eukaryotes, bacteria also offer excellent models to explore the effects of n(e). most notably, the genomes of host-dependent bacteria with small n(e) show signatures of genetic drift, including elevated k(a)/k(s). here, i explore the utility of an alternative measure of sele ... | 2011 | 22194947 |
| multiple origins of endosymbiosis within the enterobacteriaceae (gamma-proteobacteria): convergence of complex phylogenetic approaches. | abstract: background: the bacterial family enterobacteriaceae gave rise to a variety of symbiotic forms, from the loosely associated commensals, often designated as secondary (s) symbionts, to obligate mutualists, called primary (p) symbionts. determination of the evolutionary processes behind this phenomenon has long been hampered by the unreliability of phylogenetic reconstructions within this group of bacteria. the main reasons have been the absence of sufficient data, the highly derived nat ... | 2011 | 22201529 |
| purifying selection, sequence composition and context-specific indel mutations shape intraspecific variation in a bacterial endosymbiont. | comparative genomics of closely related bacterial strains can clarify mutational processes and selective forces that impact genetic variation. among primary bacterial endosymbionts of insects, such analyses have revealed ongoing genome reduction, raising questions about the ultimate evolutionary fate of these partnerships. here, we explored genomic variation within blochmannia vafer, an obligate mutualist of the ant camponotus vafer. polymorphism analysis of the illumina dataset used previously ... | 2011 | 22117087 |
| bacteria associated with gut lumen of camponotus japonicus mayr. | camponotus ants harbor the obligate intracellular endosymbiont blochmannia in their midgut bacteriocytes, but little is known about intestinal bacteria living in the gut lumen. in this paper we reported the results of a survey of the intestinal microflora of camponotus japonicus mayr based on small-subunit rrna genes (16s rrnas) polymerase chain reaction (pcr)-restriction fragment-length polymorphism analysis of worker guts. from 107 clones, 11 different restriction fragment-length polymorphism ... | 2011 | 22217755 |