Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| structure and biosynthesis of free lipid a molecules that replace lipopolysaccharide in francisella tularensis subsp. novicida. | francisella tularensis subsp. novicida u112 phospholipids, extracted without hydrolysis, consist mainly of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, and two lipid a species, designated a1 and a2. these lipid a species, present in a ratio of 7:1, comprise 15% of the total phospholipids, as judged by 32pi labeling. although lipopolysaccharide is detectable in f. tularensis subsp. novicida u112, less than 5% of the total lipid a is covalently linked to it. a1 and a2 were ... | 2006 | 17128982 |
| increased susceptibility to repeated freeze-thaw cycles in escherichia coli following long-term evolution in a benign environment. | in order to study the dynamics of evolutionary change, 12 populations of e. coli b were serially propagated for 20,000 generations in minimal glucose medium at constant 37 degrees c. correlated changes in various other traits have been previously associated with the improvement in competitive fitness in the selective environment. this study examines whether these evolved lines changed in their ability to tolerate the stresses of prolonged freezing and repeated freeze-thaw cycles during adaptatio ... | 2006 | 17147797 |
| only one of five groel genes is required for viability and successful symbiosis in sinorhizobium meliloti. | many bacterial species contain multiple copies of the genes that encode the chaperone groel and its cochaperone, groes, including all of the fully sequenced root-nodulating bacteria that interact symbiotically with legumes to generate fixed nitrogen. in particular, in sinorhizobium meliloti there are four groesl operons and one groel gene. to uncover functional redundancies of these genes during growth and symbiosis, we attempted to construct strains containing all combinations of groel mutation ... | 2007 | 17158666 |
| only one of five groel genes is required for viability and successful symbiosis in sinorhizobium meliloti. | many bacterial species contain multiple copies of the genes that encode the chaperone groel and its cochaperone, groes, including all of the fully sequenced root-nodulating bacteria that interact symbiotically with legumes to generate fixed nitrogen. in particular, in sinorhizobium meliloti there are four groesl operons and one groel gene. to uncover functional redundancies of these genes during growth and symbiosis, we attempted to construct strains containing all combinations of groel mutation ... | 2007 | 17158666 |
| the sxt conjugative element and linear prophage n15 encode toxin-antitoxin-stabilizing systems homologous to the tad-ata module of the paracoccus aminophilus plasmid pami2. | a group of proteic toxin-antitoxin (ta) cassettes whose representatives are widely distributed among bacterial genomes has been identified. these cassettes occur in chromosomes, plasmids, bacteriophages, and noncomposite transposons, as well as in the sxt conjugative element of vibrio cholerae. the following four homologous loci were subjected to detailed comparative studies: (i) tad-ata from plasmid pami2 of paracoccus aminophilus (the prototype of this group), (ii) gp49-gp48 from the linear ba ... | 2007 | 17158670 |
| the sxt conjugative element and linear prophage n15 encode toxin-antitoxin-stabilizing systems homologous to the tad-ata module of the paracoccus aminophilus plasmid pami2. | a group of proteic toxin-antitoxin (ta) cassettes whose representatives are widely distributed among bacterial genomes has been identified. these cassettes occur in chromosomes, plasmids, bacteriophages, and noncomposite transposons, as well as in the sxt conjugative element of vibrio cholerae. the following four homologous loci were subjected to detailed comparative studies: (i) tad-ata from plasmid pami2 of paracoccus aminophilus (the prototype of this group), (ii) gp49-gp48 from the linear ba ... | 2007 | 17158670 |
| stimulus perception in bacterial signal-transducing histidine kinases. | two-component signal-transducing systems are ubiquitously distributed communication interfaces in bacteria. they consist of a histidine kinase that senses a specific environmental stimulus and a cognate response regulator that mediates the cellular response, mostly through differential expression of target genes. histidine kinases are typically transmembrane proteins harboring at least two domains: an input (or sensor) domain and a cytoplasmic transmitter (or kinase) domain. they can be identifi ... | 2006 | 17158704 |
| lengsin is a survivor of an ancient family of class i glutamine synthetases re-engineered by evolution for a role in the vertebrate lens. | lengsin is a major protein of the vertebrate eye lens. it belongs to the hitherto purely prokaryotic gs i branch of the glutamine synthetase (gs) superfamily, but has no enzyme activity. like the taxon-specific crystallins, lengsin is the result of the recruitment of an ancient enzyme to a noncatalytic role in the vertebrate lens. cryo-em and modeling studies of lengsin show a dodecamer structure with important similarities and differences with prokaryotic gs i structures. gs homology regions of ... | 2006 | 17161372 |
| the major chemotaxis gene cluster of rhizobium leguminosarum bv. viciae is essential for competitive nodulation. | rhizobium leguminosarum biovar viciae strain 3841 is a motile alpha-proteobacterium that can establish a nitrogen-fixing symbiosis within the roots of pea plants. in order to determine the contribution of chemotaxis to the lifestyle of r. leguminosarum, we have characterized the function of two chemotaxis gene clusters (che1 and che2) in controlling motility behaviour. we have found that both chemotaxis gene clusters modulate the motility swimming bias of r. leguminosarum cells and that the che1 ... | 2007 | 17163982 |
| computational reconstruction of iron- and manganese-responsive transcriptional networks in alpha-proteobacteria. | we used comparative genomics to investigate the distribution of conserved dna-binding motifs in the regulatory regions of genes involved in iron and manganese homeostasis in alpha-proteobacteria. combined with other computational approaches, this allowed us to reconstruct the metal regulatory network in more than three dozen species with available genome sequences. we identified several classes of cis-acting regulatory dna motifs (irr-boxes or ices, rira-boxes, iron-rhodo-boxes, fur-alpha-boxes, ... | 2006 | 17173478 |
| mariner mutagenesis of brucella melitensis reveals genes with previously uncharacterized roles in virulence and survival. | random gene inactivation used to identify cellular functions associated with virulence and survival of brucella spp has relied heavily upon the use of the transposon tn5 that integrates at g/c base pairs. transposons of the mariner family do not require species-specific host factors for efficient transposition, integrate nonspecifically at t/a base pairs, and, at a minimum, provide an alternative approach for gene discovery. in this study, plasmid vector psc189, containing both the hyperactive t ... | 2006 | 17176467 |
| a plasmid sequence from rhizobium leguminosarum 300 contains homology to sequences near the octopine tl-dna right border. | the dna sequence from a rhizobium leguminosarum 300 (rl300) plasmid that contains homology to the tc-dna of agrobacterium tumefaciens is described. the rl300 sequence has 78% homology to a 359 bp sequence in the tc-dna of pti15955. the rl300 homology starts approximately 100 bp from the 24 bp border sequence of the tl-dna and ends approximately 3 bp from an is66 homolog in the tc-dna. an unusual feature of the rl300 homology is the presence of 81 bp direct repeats with tc-dna homology, separated ... | 1987 | 17193713 |
| the lipopolysaccharide of sinorhizobium meliloti suppresses defense-associated gene expression in cell cultures of the host plant medicago truncatula. | in the establishment of symbiosis between medicago truncatula and the nitrogen-fixing bacterium sinorhizobium meliloti, the lipopolysaccharide (lps) of the microsymbiont plays an important role as a signal molecule. it has been shown in cell cultures that the lps is able to suppress an elicitor-induced oxidative burst. to investigate the effect of s. meliloti lps on defense-associated gene expression, a microarray experiment was performed. for evaluation of the m. truncatula microarray datasets, ... | 2007 | 17220366 |
| the francisella pathogenicity island protein igla localizes to the bacterial cytoplasm and is needed for intracellular growth. | francisella tularensis is a gram negative, facultative intracellular bacterium that is the etiological agent of tularemia. f. novicida is closely related to f. tularensis but has low virulence for humans while being highly virulent in mice. igla is a 21 kda protein encoded by a gene that is part of an iglabcd operon located on the francisella pathogenicity island (fpi). | 2007 | 17233889 |
| the symbiosis regulator cbra modulates a complex regulatory network affecting the flagellar apparatus and cell envelope proteins. | sinorhizobium meliloti participates in a nitrogen-fixing symbiosis with legume plant host species of the genera medicago, melilotus, and trigonella. we recently identified an s. meliloti two-component sensory histidine kinase, cbra, which is absolutely required to establish a successful symbiosis with medicago sativa (k. e. gibson, g. r. campbell, j. lloret, and g. c. walker, j. bacteriol. 188:4508-4521, 2006). in addition to having a symbiotic defect, the cbra::tn5 mutant also has free-living p ... | 2007 | 17237174 |
| a novel superfamily containing the beta-grasp fold involved in binding diverse soluble ligands. | domains containing the beta-grasp fold are utilized in a great diversity of physiological functions but their role, if any, in soluble or small molecule ligand recognition is poorly studied. | 2007 | 17250770 |
| pleiotropic effects of mutations that alter the sinorhizobium meliloti cytochrome c respiratory system. | using transposon mutagenesis, mutations have been isolated in several genes (ccda, cycm, ccmc, ccmb and senc) that play a role in sinorhizobium meliloti cytochrome metabolism. as in other bacteria, mutations in the s. meliloti ccda, ccmb and ccmc genes resulted in the absence of all c-type cytochromes. however, the s. meliloti ccda mutant also lacked cytochrome oxidase aa(3), a defect that does not appear to have been reported for other bacteria. the aa(3)-type cytochromes were also missing from ... | 2007 | 17259611 |
| a complete set of flagellar genes acquired by horizontal transfer coexists with the endogenous flagellar system in rhodobacter sphaeroides. | bacteria swim in liquid environments by means of a complex rotating structure known as the flagellum. approximately 40 proteins are required for the assembly and functionality of this structure. rhodobacter sphaeroides has two flagellar systems. one of these systems has been shown to be functional and is required for the synthesis of the well-characterized single subpolar flagellum, while the other was found only after the genome sequence of this bacterium was completed. in this work we found th ... | 2007 | 17293429 |
| meningococcal genetic variation mechanisms viewed through comparative analysis of serogroup c strain fam18. | the bacterium neisseria meningitidis is commonly found harmlessly colonising the mucosal surfaces of the human nasopharynx. occasionally strains can invade host tissues causing septicaemia and meningitis, making the bacterium a major cause of morbidity and mortality in both the developed and developing world. the species is known to be diverse in many ways, as a product of its natural transformability and of a range of recombination and mutation-based systems. previous work on pathogenic neisser ... | 2007 | 17305430 |
| living without fur: the subtlety and complexity of iron-responsive gene regulation in the symbiotic bacterium rhizobium and other alpha-proteobacteria. | the alpha-proteobacteria include several important genera, including the symbiotic n(2)-fixing "rhizobia", the plant pathogen agrobacterium, the mammalian pathogens brucella, bartonella as well as many others that are of environmental or other interest--including rhodobacter, caulobacter and the hugely abundant marine genus pelagibacter. only a few species--mainly different members of the rhizobia--have been analyzed directly for their ability to use and to respond to iron. these studies, howeve ... | 2007 | 17310401 |
| role of soil rhizobacteria in phytoremediation of heavy metal contaminated soils. | heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential ... | 2007 | 17323432 |
| inhibition of lipid a biosynthesis as the primary mechanism of chir-090 antibiotic activity in escherichia coli. | the deacetylation of udp-3-o-[(r)-3-hydroxymyristoyl]-n-acetylglucosamine (udp-3-o-acyl-glcnac) by lpxc is the committed reaction of lipid a biosynthesis. chir-090, a novel n-aroyl-l-threonine hydroxamic acid, is a potent, slow, tight-binding inhibitor of the lpxc deacetylase from the hyperthermophile aquifex aeolicus, and it has excellent antibiotic activity against pseudomonas aeruginosa and escherichia coli, as judged by disk diffusion assays. we now report that chir-090 is also a two-step sl ... | 2007 | 17335290 |
| characterization of sinorhizobium meliloti triose phosphate isomerase genes. | a tn5 mutant strain of sinorhizobium meliloti with an insertion in tpia (systematic identifier smc01023), a putative triose phosphate isomerase (tpi)-encoding gene, was isolated. the tpia mutant grew more slowly than the wild type on rhamnose and did not grow with glycerol as a sole carbon source. the genome of s. meliloti wild-type rm1021 contains a second predicted tpi-encoding gene, tpib (smc01614). we have constructed mutations and confirmed that both genes encode functional tpi enzymes. tpi ... | 2007 | 17337584 |
| finding the needles in the metagenome haystack. | in the collective genomes (the metagenome) of the microorganisms inhabiting the earth's diverse environments is written the history of life on this planet. new molecular tools developed and used for the past 15 years by microbial ecologists are facilitating the extraction, cloning, screening, and sequencing of these genomes. this approach allows microbial ecologists to access and study the full range of microbial diversity, regardless of our ability to culture organisms, and provides an unpreced ... | 2007 | 17345132 |
| quorum-sensing regulation in rhizobia and its role in symbiotic interactions with legumes. | legume-nodulating bacteria (rhizobia) usually produce n-acyl homoserine lactones, which regulate the induction of gene expression in a quorum-sensing (or population-density)-dependent manner. there is significant diversity in the types of quorum-sensing regulatory systems that are present in different rhizobia and no two independent isolates worked on in detail have the same complement of quorum-sensing genes. the genes regulated by quorum sensing appear to be rather diverse and many are associa ... | 2007 | 17360278 |
| look who's talking: communication and quorum sensing in the bacterial world. | for many years bacteria were considered primarily as autonomous unicellular organisms with little capacity for collective behaviour. however, we now appreciate that bacterial cells are in fact, highly communicative. the generic term 'quorum sensing' has been adopted to describe the bacterial cell-to-cell communication mechanisms which co-ordinate gene expression usually, but not always, when the population has reached a high cell density. quorum sensing depends on the synthesis of small molecule ... | 2007 | 17360280 |
| attenuated virulence of a francisella mutant lacking the lipid a 4'-phosphatase. | francisella tularensis causes tularemia, a highly contagious disease of animals and humans, but the virulence features of f. tularensis are poorly defined. f. tularensis and the related mouse pathogen francisella novicida synthesize unusual lipid a molecules lacking the 4'-monophosphate group typically found in the lipid a of gram-negative bacteria. lpxf, a selective phosphatase located on the periplasmic surface of the inner membrane, removes the 4'-phosphate moiety in the late stages of f. nov ... | 2007 | 17360489 |
| lipid a modification systems in gram-negative bacteria. | the lipid a moiety of lipopolysaccharide forms the outer monolayer of the outer membrane of most gram-negative bacteria. escherichia coli lipid a is synthesized on the cytoplasmic surface of the inner membrane by a conserved pathway of nine constitutive enzymes. following attachment of the core oligosaccharide, nascent core-lipid a is flipped to the outer surface of the inner membrane by the abc transporter msba, where the o-antigen polymer is attached. diverse covalent modifications of the lipi ... | 2007 | 17362200 |
| [the pssa gene encodes udp-glucose: polyprenyl phosphate-glucosyl phosphotransferase initiating biosynthesis of rhizobium leguminosarum exopolysaccharide]. | symbiotic nitrogen-fixing bacteria rhizobium leguminosarum by. viciae vf39 secrete an acidic heteropolysaccharide, the biosynthesis of which involves the stage of polyprenyl diphosphate octasaccharide formation, with its carbohydrate fragment corresponding to the repeating polymer unit. the amino acid analysis of the product of the pssa gene, we have earlier identified, showed its homology to bacterial polyisoprenyl phosphate hexose 1-phosphate transferases catalyzing the formation of phosphodie ... | 2007 | 17375671 |
| symbiosis-induced cascade regulation of the mesorhizobium loti r7a virb/d4 type iv secretion system. | the mesorhizobium loti r7a symbiosis island contains genes encoding a virb/d4 type iv secretion system (t4ss) similar to that of agrobacterium tumefaciens. this system has host-dependent effects on symbiosis that probably are due to translocation of two effector proteins, msi059 and msi061, into host cells. here we report that, as in a. tumefaciens, the m. loti vir genes are transcriptionally regulated by a vira/virg two-component regulatory system. a virgn54d mutant gene of m. loti caused const ... | 2007 | 17378428 |
| rhizobium-initiated rice growth inhibition caused by nitric oxide accumulation. | isolates of rhizobium leguminosarum bv. trifolii (the clover root-nodule endosymbiont) from the nile river delta have been found to infect rice roots and colonize the intercellular spaces of the rice roots. some of these isolates inhibit rice seedling growth but one in particular, r4, has been found in rice roots which develop and grow normally. we present evidence that the induced growth inhibition is due to a toxic accumulation of nitric oxide (no), from the reduction of nitrate, and suggest t ... | 2007 | 17378431 |
| abnormal root and nodule vasculature in r50 (sym16), a pea nodulation mutant which accumulates cytokinins. | r50 (sym16) is a pea nodulation mutant with fewer and shorter lateral roots (lr), fewer nodules and high levels of cytokinins (ck). because a link exists between ck imbalance and abnormal vasculature, the vasculature of the primary root (pr) and lr of r50 was studied and it was compared with that of the wild-type 'sparkle'. also nodule vasculature was investigated to correlate r50 low nodulation phenotype with ck accumulation. | 2007 | 17383989 |
| effector-stimulated single molecule protein-dna interactions of a quorum-sensing system in sinorhizobium meliloti. | intercellular communication by means of small signal molecules coordinates gene expression among bacteria. this population density-dependent regulation is known as quorum sensing. the symbiotic nitrogen-fixing bacterium sinorhizobium meliloti rm1021 possesses the sin quorum sensing system based on n-acyl homoserine lactones (ahl) as signal molecules. here, we demonstrate that the luxr-type regulator expr binds specifically to a target sequence in the sinri locus in the presence of different ahls ... | 2007 | 17384071 |
| response of inoculated foliar fed pea plants (pisum sativum l.) to reduced mo supply. | the application of nutrients to the roots and leaves of inoculated pea plants grown under conditions of reduced mo supply was studied. pea plants (pisum sativum l.) were grown on liquid nutrient solution excluding mo from the media until the 35th day under glasshouse conditions. plants were inoculated with the bacterial suspension of rhizobium leguminosarum bv. vicae, strain d293 at approximately 10(8) cells per cm3. the foliar fertilizer agroleaf was applied at 0.3% concentration. changes in th ... | 2007 | 17385546 |
| an extracytoplasmic function sigma factor acts as a general stress response regulator in sinorhizobium meliloti. | sinorhizobium meliloti genes transcriptionally up-regulated after heat stress, as well as upon entry into stationary phase, were identified by microarray analyses. sixty stress response genes were thus found to be up-regulated under both conditions. one of them, rpoe2 (smc01506), encodes a putative extracytoplasmic function (ecf) sigma factor. we showed that this sigma factor controls its own transcription and is activated by various stress conditions, including heat and salt, as well as entry i ... | 2007 | 17400745 |
| a marine mesorhizobium sp. produces structurally novel long-chain n-acyl-l-homoserine lactones. | our study focused on a mesorhizobium sp. that is phylogenetically affiliated by 16s rrna gene sequence to other marine and saline bacteria of this genus. liquid chromatography-mass spectrometry investigations of the extract obtained from solid-phase extraction of cultures of this bacterium indicated the presence of several n-acyl homoserine lactones (ahls), with chain lengths of c(10) to c(16). chromatographic separation of the active bacterial extract yielded extraordinarily large amounts of tw ... | 2007 | 17400774 |
| responses of rhizobia to desiccation in relation to osmotic stress, oxygen, and temperature. | 2007 | 17400779 | |
| nitrogen fixation control under drought stress. localized or systemic? | legume-rhizobium nitrogen fixation is dramatically affected under drought and other environmental constraints. however, it has yet to be established as to whether such regulation of nitrogen fixation is only exerted at the whole-plant level (e.g. by a systemic nitrogen feedback mechanism) or can also occur at a local nodule level. to address this question, nodulated pea (pisum sativum) plants were grown in a split-root system, which allowed for half of the root system to be irrigated at field ca ... | 2007 | 17416644 |
| rhizavidin from rhizobium etli: the first natural dimer in the avidin protein family. | rhizobium etli cfn42 is a symbiotic nitrogen-fixing bacterium of the common bean phaseolus vulgaris. the symbiotic plasmid p42d of r. etli comprises a gene encoding a putative (strept)avidin-like protein, named rhizavidin. the amino acid sequence identity of rhizavidin in relation to other known avidin-like proteins is 20-30%. the amino acid residues involved in the (strept)avidin-biotin interaction are well conserved in rhizavidin. the structural and functional properties of rhizavidin were car ... | 2007 | 17447892 |
| developmental genes have pleiotropic effects on plant morphology and source capacity, eventually impacting on seed protein content and productivity in pea. | increasing pea (pisum sativum) seed nutritional value and particularly seed protein content, while maintaining yield, is an important challenge for further development of this crop. seed protein content and yield are complex and unstable traits, integrating all the processes occurring during the plant life cycle. during filling, seeds are the main sink to which assimilates are preferentially allocated at the expense of vegetative organs. nitrogen seed demand is satisfied partly by nitrogen acqui ... | 2007 | 17449650 |
| identification of a gene cluster enabling lactobacillus casei bl23 to utilize myo-inositol. | genome analysis of lactobacillus casei bl23 revealed that, compared to l. casei atcc 334, it carries a 12.8-kb dna insertion containing genes involved in the catabolism of the cyclic polyol myo-inositol (mi). indeed, l. casei atcc 334 does not ferment mi, whereas strain bl23 is able to utilize this carbon source. the inserted dna consists of an iolr gene encoding a deor family transcriptional repressor and a divergently transcribed ioltabcdg1g2ejk operon, encoding a complete mi catabolic pathway ... | 2007 | 17449687 |
| trehalose biosynthesis in rhizobium leguminosarum bv. trifolii and its role in desiccation tolerance. | rhizobium leguminosarum bv. trifolii forms nitrogen-fixing root nodules on the pasture legume trifolium repens, and t. repens seed is often coated with a compatible r. leguminosarum bv. trifolii strain prior to sowing. however, significant losses in bacterial viability occur during the seed-coating process and during storage of the coated seeds, most likely due to desiccation stress. the disaccharide trehalose is known to function as an osmoprotectant, and trehalose accumulation due to de novo b ... | 2007 | 17449695 |
| mutagenesis of the carboxy terminal protease ctpa decreases desiccation tolerance in rhizobium leguminosarum. | to better understand the role of proteases in rhizobium leguminosarum biovar viciae, a gene with homology to the carboxy-terminal protease (ctpa), which belongs to a novel group of serine proteases, was studied. the ctpa gene was cloned and mutated using allelic exchange and a gusa reporter gene was used to study ctpa expression. mutational analysis shows that ctpa is critical for the viability of r. leguminosarum when cells are grown on complex semi-solid media but is dispensable when cells are ... | 2007 | 17456188 |
| using the ralstonia solanacearum tat secretome to identify bacterial wilt virulence factors. | to identify secreted virulence factors involved in bacterial wilt disease caused by the phytopathogen ralstonia solanacearum, we mutated tatc, a key component of the twin-arginine translocation (tat) secretion system. the r. solanacearum tatc mutation was pleiotropic; its phenotypes included defects in cell division, nitrate utilization, polygalacturonase activity, membrane stability, and growth in plant tissue. bioinformatic analysis of the r. solanacearum strain gmi1000 genome predicted that t ... | 2007 | 17468289 |
| [a study of the competitive properties of the aluminum-tolerant strain rhizobium leguminosarum bv. trifolii 9-4a by the antibiotic resistance method]. | the virulence, competitive ability, and symbiotic efficiency of 2 rhizobium leguminosarum bv. trifolii strains--the wild aluminum tolerant strain 9-4a and the commercial strain 348a-were compared when introducing their variants marked with antibiotic resistance into the rhizosphere of red clover (trifolium pratense l.) plants. high virulence and competitive ability of the strain tolerant to aluminum was demonstrated by a concurrent inoculation of the seeds with these two strains. the resistance ... | 2007 | 17476807 |
| [active oxygen species in pea seedlings during the interactions with symbiotic and pathogenic microorganisms]. | the level of active oxygen species (aos)--superoxide anion radical (o2*-) and hydrogen peroxide (h2o2)--in pea (pisum sativum l.) cultivar marat seedlings was studied upon their inoculation with symbiotic (rhizobium leguminosarum bv. viceae strain ciam 1026) and pathogenic (pseudomonas syringae pv. pisi sackett) microorganisms. different patterns of the changes in aos in pea seedlings during the interactions with the symbiont and the phytopathogen were recorded. it is assumed that o2*- and h2o2 ... | 2007 | 17476814 |
| genetic diversity of rhizobia associated with vicia faba in three ecological regions of china. | great genetic diversity was revealed among 75 rhizobal isolates associated with vicia faba grown in chinese fields with aflp, ardra, 16s rdna sequencing, dna-dna hybridization, box-pcr and rflp of pcr-amplified nodd and nodc. most of the isolates were rhizobium leguminosarum, and six isolates belonged to an unnamed rhizobium species. in the homogeneity analysis, the isolates were grouped into three clusters corresponding to (1) autumn sowing (subtropical) region where the winter ecotype of v. fa ... | 2007 | 17479251 |
| auxin and nitric oxide control indeterminate nodule formation. | rhizobia symbionts elicit root nodule formation in leguminous plants. nodule development requires local accumulation of auxin. both plants and rhizobia synthesise auxin. we have addressed the effects of bacterial auxin (iaa) on nodulation by using sinorhizobium meliloti and rhizobium leguminosarum bacteria genetically engineered for increased auxin synthesis. | 2007 | 17488509 |
| horizontal gene transfer and homologous recombination drive the evolution of the nitrogen-fixing symbionts of medicago species. | using nitrogen-fixing sinorhizobium species that interact with medicago plants as a model system, we aimed at clarifying how sex has shaped the diversity of bacteria associated with the genus medicago on the interspecific and intraspecific scales. to gain insights into the diversification of these symbionts, we inferred a topology that includes the different specificity groups which interact with medicago species, based on sequences of the nodulation gene cluster. furthermore, 126 bacterial isol ... | 2007 | 17496100 |
| bioformulation of burkholderia sp. mssp with a multispecies consortium for growth promotion of cajanus cajan. | the present work was undertaken to formulate an effective bioformulation using burkholderia sp. strain mssp, a known plant-growth-promoting rhizobacterium. mssp was tagged with the reporter gene of green fluorescent protein (gfp) to monitor its population in cost-effective solid carriers, including sugarcane-bagasse, sawdust, cocoa peat, rice husk, wheat bran, charcoal, and rock phosphate, and paneer-whey as liquid carrier. physical and chemical properties of different low-cost carrier materials ... | 2007 | 17496969 |
| functional characterization of the sinorhizobium meliloti acetate metabolism genes acea, smc00767, and glcb. | the genes encoding malate synthase (glcb) and isocitrate lyase (acea) and a 240-bp open reading frame (smc00767) located downstream of acea were isolated and functionally characterized in sinorhizobium meliloti. independent and double interposon mutants of each gene were constructed, and the corresponding phenotypes were analyzed. acea mutants failed to grow on acetate, and mutants deficient in smc00767 were also affected in acetate utilization. in contrast, mutants deficient in glcb grew on ace ... | 2007 | 17526694 |
| context dependence in the coevolution of plant and rhizobial mutualists. | several mechanisms are expected to rapidly rid mutualisms of genetic variation in partner quality. variation for mutualist quality, however, appears to be widespread. we used a model legume-rhizobium mutualism to test for evidence that context-dependent selection may maintain variation in partner quality. in a greenhouse experiment using 10 natural populations of medicago truncatula and two strains of sinorhizobium medicae, we detected significant genotype x genotype (g x g) interactions for pla ... | 2007 | 17535796 |
| aspartate-444 is essential for productive substrate interactions in a neuronal glutamate transporter. | in the central nervous system, electrogenic sodium- and potassium-coupled glutamate transporters terminate the synaptic actions of this neurotransmitter. in contrast to acidic amino acids, dicarboxylic acids are not recognized by glutamate transporters, but the related bacterial dcta transporters are capable of transporting succinate and other dicarboxylic acids. transmembrane domain 8 contains several residues that differ between these two types of transporters. one of these, aspartate-444 of t ... | 2007 | 17535962 |
| characterization of symbiotic and endophytic bacteria isolated from root nodules of herbaceous legumes grown in qinghai-tibet plateau and in other zones of china. | qinghai-tibet plateau is the highest place in the world and the environment in that plateau is hard for animals and plants, with low temperature, low concentration of oxygen and high solar radiation. in this study, 61 root nodule isolates from vicia, oxytropis, medicago, melilotus and onobrychis species grown in qinghai-tibet plateau and in loess plateau were comparatively characterized. based upon the results of numerical taxonomy, ardra, aflp, dna-dna hybridization and 16s rdna sequencing, the ... | 2007 | 17541555 |
| agrobacterium tumefaciens fur has important physiological roles in iron and manganese homeostasis, the oxidative stress response, and full virulence. | in agrobacterium tumefaciens, the balance between acquiring enough iron and avoiding iron-induced toxicity is regulated in part by fur (ferric uptake regulator). a fur mutant was constructed to address the physiological role of the regulator. atypically, the mutant did not show alterations in the levels of siderophore biosynthesis and the expression of iron transport genes. however, the fur mutant was more sensitive than the wild type to an iron chelator, 2,2'-dipyridyl, and was also more resist ... | 2007 | 17545320 |
| isolation and characterization of a novel haloacid permease from burkholderia cepacia mba4. | burkholderia cepacia mba4 is a bacterium that can utilize 2-haloacids as carbon and energy sources for growth. it has been proposed that dehalogenase-associated permease mediates the uptake of haloacid. in this paper, we report the first cloning and characterization of such a haloacid permease. the structural gene, designated deh4p, was found 353 bases downstream of the dehalogenase gene deh4a. quantitative analysis of the expression of deh4p showed that it was induced by monochloroacetate (mca) ... | 2007 | 17545323 |
| nutrient sharing between symbionts. | 2007 | 17556524 | |
| genomes of the symbiotic nitrogen-fixing bacteria of legumes. | 2007 | 17556525 | |
| copper induction of lactate oxidase of lactococcus lactis: a novel metal stress response. | lactococcus lactis il1403, a lactic acid bacterium widely used for food fermentation, is often exposed to stress conditions. one such condition is exposure to copper, such as in cheese making in copper vats. copper is an essential micronutrient in prokaryotes and eukaryotes but can be toxic if in excess. thus, copper homeostatic mechanisms, consisting chiefly of copper transporters and their regulators, have evolved in all organisms to control cytoplasmic copper levels. using proteomics to ident ... | 2007 | 17557814 |
| mutations of the quorum sensing-dependent regulator vjbr lead to drastic surface modifications in brucella melitensis. | successful establishment of infection by bacterial pathogens requires fine-tuning of virulence-related genes. quorum sensing (qs) is a global regulation process based on the synthesis of, detection of, and response to small diffusible molecules, called n-acyl-homoserine lactones (ahl), in gram-negative bacteria. in numerous species, qs has been shown to regulate genes involved in the establishment of pathogenic interactions with the host. brucella melitensis produces n-dodecanoyl homoserine lact ... | 2007 | 17557825 |
| sinorhizobium meliloti fur-like (mur) protein binds a fur box-like sequence present in the mnta promoter in a manganese-responsive manner. | in sinorhizobium meliloti, the mur(sm) protein, a homologue of the ferric uptake regulator (fur), mediates manganese-dependent regulation of the mntabcd manganese uptake system. in this study, we analyzed mur(sm) binding to the promoter region of the s. meliloti mnta gene. we demonstrated that mur(sm) protein binds with high affinity to the promoter region of mnta gene in a manganese-responsive manner. moreover, the results presented here indicate that two monomers, or one dimer, of mur(sm) bind ... | 2007 | 17557847 |
| the novel alkali tolerance function of tfxg in sinorhizobium meliloti. | tfxg, one of the tfxabcdefg cluster genes that code for trifolitoxin (tfx) production, was initially described in rhizobium leguminosarum bv. trifolii t24. although several genes in the tfx family have functions related to tfx production or resistance to tfx, the function of tfxg is largely unknown. using cdna-amplified fragment length polymorphism (cdna-aflp) analysis, we found that expression of the tfxg gene dramatically increased under alkaline culture conditions in sinorhizobium meliloti cc ... | 2007 | 17566711 |
| transcriptional regulation of the heme binding protein gene family of bartonella quintana is accomplished by a novel promoter element and iron response regulator. | we previously identified a five-member family of hemin-binding proteins (hbp's) of bartonella quintana that bind hemin on the outer surface but share no homology with known bacterial heme receptors. subsequently, we demonstrated that expression of the hbp family is significantly influenced by oxygen, heme, and temperature conditions encountered by the pathogen in the human host and the body louse vector; e.g., we observed a dramatic (>100-fold) increase in hbpc transcript levels in response to t ... | 2007 | 17576755 |
| large genotypic variation but small variation in n2 fixation among rhizobia nodulating red clover in soils of northern scandinavia. | to analyse the symbiotic variations within indigenous populations of rhizobia nodulating red clover (trifolium pratense l.) in soils of northern norway and sweden at different times of the growing season. | 2007 | 17578428 |
| brucella suis urease encoded by ure1 but not ure2 is necessary for intestinal infection of balb/c mice. | in prokaryotes, the ureases are multi-subunit, nickel-containing enzymes that catalyze the hydrolysis of urea to carbon dioxide and ammonia. the brucella genomes contain two urease operons designated as ure1 and ure2. we investigated the role of the two brucella suis urease operons on the infection, intracellular persistence, growth, and resistance to low-ph killing. | 2007 | 17578575 |
| bigr, a transcriptional repressor from plant-associated bacteria, regulates an operon implicated in biofilm growth. | xylella fastidiosa is a plant pathogen that colonizes the xylem vessels, causing vascular occlusion due to bacterial biofilm growth. however, little is known about the molecular mechanisms driving biofilm formation in xylella-plant interactions. here we show that bigr (for "biofilm growth-associated repressor") is a novel helix-turn-helix repressor that controls the transcription of an operon implicated in biofilm growth. this operon, which encodes bigr, membrane proteins, and an unusual beta-la ... | 2007 | 17586627 |
| quorum-sensing-regulated transcriptional initiation of plasmid transfer and replication genes in rhizobium leguminosarum biovar viciae. | transfer of the rhizobium leguminosarum biovar viciae symbiosis plasmid prl1ji is regulated by a cascade of gene induction involving three luxr-type quorum-sensing regulators, trar, bisr and cinr. trar induces the plasmid transfer trai-trb operon in a population-density-dependent manner in response to n-acylhomoserine lactones (ahls) made by trai. expression of the trar gene is primarily induced by bisr in response to ahls made by cini, and expression of cini is induced by cinr and repressed by ... | 2007 | 17600052 |
| the rhizobium leguminosarum bv. trifolii rosr: transcriptional regulator involved in exopolysaccharide production. | the acidic exopolysaccharide is required for the establishment of symbiosis between the nitrogen-fixing bacterium rhizobium leguminosarum bv. trifolii and clover. here, we describe rosr protein from r. leguminosarum bv. trifolii 24.2, a homolog of transcriptional regulators belonging to the family of ros/mucr proteins. r. leguminosarum bv. trifolii rosr possesses a characteristic cys2his2 type zinc-finger motif in its c-terminal domain. recombinant (his)6rosr binds to an rosr-box sequence locate ... | 2007 | 17601173 |
| [the effect of inoculation with rhizobium leguminosarum on the contents of cytoplasmic protein and free amino acids in the roots of pea seedlings]. | the changes in the contents of protein and free amino acids in pea plants inoculated with rhizobium leguminosarum were studied taking into account the susceptibility of roots to root nodule bacteria. the content of cytoplasmic protein during infection increased in the actively growing root region (0-5 mm) and decreased in the root regions susceptible to rhizobia (5-20 mm from the root tip). the quantitative composition of free amino acids changed essentially upon inoculation of pea seedlings wit ... | 2007 | 17619576 |
| how rhizobial symbionts invade plants: the sinorhizobium-medicago model. | nitrogen-fixing rhizobial bacteria and leguminous plants have evolved complex signal exchange mechanisms that allow a specific bacterial species to induce its host plant to form invasion structures through which the bacteria can enter the plant root. once the bacteria have been endocytosed within a host-membrane-bound compartment by root cells, the bacteria differentiate into a new form that can convert atmospheric nitrogen into ammonia. bacterial differentiation and nitrogen fixation are depend ... | 2007 | 17632573 |
| controlled synthesis of the dsf cell-cell signal is required for biofilm formation and virulence in xanthomonas campestris. | virulence of the black rot pathogen xanthomonas campestris pv. campestris (xcc) is regulated by cell-cell signalling involving the diffusible signal factor dsf. synthesis and perception of dsf require products of genes within the rpf cluster (for regulation of pathogenicity factors). rpff directs dsf synthesis whereas rpfc and rpfg are involved in dsf perception. here we have examined the role of the rpf/dsf system in biofilm formation in minimal medium using confocal laser-scanning microscopy o ... | 2007 | 17635553 |
| comparative genomic reconstruction of transcriptional regulatory networks in bacteria. | 2007 | 17636889 | |
| the expr/sin quorum-sensing system controls succinoglycan production in sinorhizobium meliloti. | sinorhizobium meliloti is a gram-negative soil bacterium capable of forming a symbiotic nitrogen-fixing relationship with its plant host, medicago sativa. various bacterially produced factors are essential for successful nodulation. for example, at least one of two exopolysaccharides produced by s. meliloti (succinoglycan or eps ii) is required for nodule invasion. both of these polymers are produced in high- and low-molecular-weight (hmw and lmw, respectively) fractions; however, only the lmw f ... | 2007 | 17644606 |
| roles of curli, cellulose and bapa in salmonella biofilm morphology studied by atomic force microscopy. | curli, cellulose and the cell surface protein bapa are matrix components in salmonella biofilms. in this study we have investigated the roles of these components for the morphology of bacteria grown as colonies on agar plates and within a biofilm on submerged mica surfaces by applying atomic force microscopy (afm) and light microscopy. | 2007 | 17650335 |
| transcriptional and physiological responses of bradyrhizobium japonicum to desiccation-induced stress. | the growth and persistence of rhizobia and bradyrhizobia in soils are negatively impacted by drought conditions. in this study, we used genome-wide transcriptional analyses to obtain a comprehensive understanding of the response of bradyrhizobium japonicum to drought. desiccation of cells resulted in the differential expression of 15 to 20% of the 8,453 [corrected] b. japonicum open reading frames, with considerable differentiation between early (after 4 h) and late (after 24 and 72 h) expressed ... | 2007 | 17660288 |
| genetic variability in nodulation and root growth affects nitrogen fixation and accumulation in pea. | legume nitrogen is derived from two different sources, symbiotically fixed atmospheric n(2) and soil n. the effect of genetic variability of root and nodule establishment on n acquisition and seed protein yield was investigated under field conditions in pea (pisum sativum). in addition, these parameters were related to the variability in preference for rhizobial genotypes. | 2007 | 17670753 |
| homologous cpn60 genes in rhizobium leguminosarum are not functionally equivalent. | many bacteria possess 2 or more genes for the chaperonin groel and the cochaperonin groes. in particular, rhizobial species often have multiple groel and groes genes, with a high degree of amino-acid similarity, in their genomes. the rhizobium leguminosarum strain a34 has 3 complete groe operons, which we have named cpn.1, cpn.2 and cpn.3. previously we have shown the cpn. 1 operon to be essential for growth, but the two other cpn operons to be dispensable. here, we have investigated the extent ... | 2007 | 17688191 |
| lysm domains mediate lipochitin-oligosaccharide recognition and nfr genes extend the symbiotic host range. | legume-rhizobium symbiosis is an example of selective cell recognition controlled by host/non-host determinants. individual bacterial strains have a distinct host range enabling nodulation of a limited set of legume species and vice versa. we show here that expression of lotus japonicus nfr1 and nfr5 nod-factor receptor genes in medicago truncatula and l. filicaulis, extends their host range to include bacterial strains, mesorhizobium loti or dzl, normally infecting l. japonicus. as a result, th ... | 2007 | 17690687 |
| diminished redundancy of outer membrane factor proteins in rhizobiales: a nodt homolog is essential for free-living rhizobium etli. | rhizobium etli is a gram-negative soil bacterium that induces nitrogen-fixing nodules on common bean roots (phaseolus vulgaris). r. etli encodes two genes homologous to nodt of rhizobium leguminosarum. nodtch is chromosomal and forms an operon with new genes resembling a multi-drug efflux pump of the resistance-nodulation-cell division (rnd) family. nodtch is the last gene of this operon and can also be independently transcribed; the gene product is located in the bacterial outer membrane. cell ... | 2007 | 17693710 |
| enzymatic synthesis of aromatic polyketides using pks4 from gibberella fujikuroi. | 2007 | 17696354 | |
| gntr family of regulators in mycobacterium smegmatis: a sequence and structure based characterization. | mycobacterium smegmatis is fast growing non-pathogenic mycobacteria. this organism has been widely used as a model organism to study the biology of other virulent and extremely slow growing species like mycobacterium tuberculosis. based on the homology of the n-terminal dna binding domain, the recently sequenced genome of m. smegmatis has been shown to possess several putative gntr regulators. a striking characteristic feature of this family of regulators is that they possess a conserved n-termi ... | 2007 | 17714599 |
| host-specific regulation of symbiotic nitrogen fixation in rhizobium leguminosarum biovar trifolii. | strains of rhizobium leguminosarum bv. trifolii (rlt) able to form effective nodules on trifolium ambiguum (caucasian clover, cc) form ineffective nodules on trifolium repens (white clover, wc), whereas strains that form effective nodules on wc usually do not nodulate cc. here, we investigate the genetic basis of the host-specific nitrogen-fixation phenotype of cc rhizobia. a cosmid library of the symbiotic plasmid from the wc rhizobium strain rlt nzp514 was introduced into the cc rhizobium stra ... | 2007 | 17768261 |
| induction of pre-infection thread structures in the leguminous host plant by mitogenic lipo-oligosaccharides of rhizobium. | root nodules of leguminous plants are symbiotic organs in which rhizobium bacteria fix nitrogen. their formation requires the induction of a nodule meristem and the formation of a tubular structure, the infection thread, through which the rhizobia reach the nodule primordium. in the rhizobium host plants pea and vetch, pre-infection thread structures always preceded the formation of infection threads. these structures consisted of cytoplasmic bridges traversing the central vacuole of outer corti ... | 1992 | 17800714 |
| rhizobium leguminosarum bv. viciae genotypes interact with pea plants in developmental responses of nodules, roots and shoots. | the variability of the developmental responses of two contrasting cultivars of pea (pisum sativum) was studied in relation to the genetic diversity of their nitrogen-fixing symbiont rhizobium leguminosarum bv. viciae. a sample of 42 strains of pea rhizobia was chosen to represent 17 genotypes predominating in indigenous rhizobial populations, the genotypes being defined by the combination of haplotypes characterized with rdna intergenic spacer and nodd gene regions as markers. we found contrasti ... | 2007 | 17822397 |
| the mesorhizobium loti purb gene is involved in infection thread formation and nodule development in lotus japonicus. | the purb and purh mutants of mesorhizobium loti exhibited purine auxotrophy and nodulation deficiency on lotus japonicus. in the presence of adenine, only the purh mutant induced nodule formation and the purb mutant produced few infection threads, suggesting that 5-aminoimidazole-4-carboxamide ribonucleotide biosynthesis catalyzed by purb is required for the establishment of symbiosis. | 2007 | 17827288 |
| genome sequence analysis of the emerging human pathogenic acetic acid bacterium granulibacter bethesdensis. | chronic granulomatous disease (cgd) is an inherited immune deficiency characterized by increased susceptibility to infection with staphylococcus, certain gram-negative bacteria, and fungi. granulibacter bethesdensis, a newly described genus and species within the family acetobacteraceae, was recently isolated from four cgd patients residing in geographically distinct locales who presented with fever and lymphadenitis. we sequenced the genome of the reference strain of granulibacter bethesdensis, ... | 2007 | 17827295 |
| type vi secretion system translocates a phage tail spike-like protein into target cells where it cross-links actin. | genes encoding type vi secretion systems (t6ss) are widely distributed in pathogenic gram-negative bacterial species. in vibrio cholerae, t6ss have been found to secrete three related proteins extracellularly, vgrg-1, vgrg-2, and vgrg-3. vgrg-1 can covalently cross-link actin in vitro, and this activity was used to demonstrate that v. cholerae can translocate vgrg-1 into macrophages by a t6ss-dependent mechanism. protein structure search algorithms predict that vgrg-related proteins likely assem ... | 2007 | 17873062 |
| structural biology of membrane-intrinsic beta-barrel enzymes: sentinels of the bacterial outer membrane. | the outer membranes of gram-negative bacteria are replete with integral membrane proteins that exhibit antiparallel beta-barrel structures, but very few of these proteins function as enzymes. in escherichia coli, only three beta-barrel enzymes are known to exist in the outer membrane; these are the phospholipase ompla, the protease ompt, and the phospholipidcolon, two colonslipid a palmitoyltransferase pagp, all of which have been characterized at the structural level. structural details have al ... | 2008 | 17880914 |
| structural biology of membrane-intrinsic beta-barrel enzymes: sentinels of the bacterial outer membrane. | the outer membranes of gram-negative bacteria are replete with integral membrane proteins that exhibit antiparallel beta-barrel structures, but very few of these proteins function as enzymes. in escherichia coli, only three beta-barrel enzymes are known to exist in the outer membrane; these are the phospholipase ompla, the protease ompt, and the phospholipidcolon, two colonslipid a palmitoyltransferase pagp, all of which have been characterized at the structural level. structural details have al ... | 2008 | 17880914 |
| l-rhamnose transport is sugar kinase (rhak) dependent in rhizobium leguminosarum bv. trifolii. | strains of rhizobium leguminosarum which are unable to catabolize l-rhamnose, a methyl-pentose sugar, are compromised in the ability to compete for nodule occupancy versus wild-type strains. previous characterization of the 11-kb region necessary for the utilization of rhamnose identified a locus carrying catabolic genes and genes encoding the components of an abc transporter. genetic evidence suggested that the putative kinase rhak carried out the first step in the catabolism of rhamnose. chara ... | 2007 | 17890304 |
| increased metabolic potential of rhizobium spp. is associated with bacterial competitiveness. | of 105 rhizobial isolates obtained from nodules of commonly cultivated legumes, we selected 19 strains on the basis of a high rate of symbiotic plant growth promotion. individual strains within the species rhizobium leguminosarum bv. trifolii, r. leguminosarum bv. viciae, and rhizobium etli displayed variation not only in plasmid sizes and numbers but also in the chromosomal 16s-23s internal transcribed spacer. the strains were tagged with gusa gene and their competitiveness was examined in rela ... | 2007 | 17898852 |
| genetic diversity of a natural population of rhizobium leguminosarum bv. viciae nodulating plants of vicia faba in the vesuvian area. | a total of 98 rhizobial strains, isolated during the winter of the years 2003 (35 isolates), 2004 (33 isolates), and 2005 (30 isolates) were analyzed to determine the genetic diversity of the natural population nodulating vicia faba plants and to identify dominant genotypes. all isolates were identified as rhizobium leguminosarum bv. viciae by biovar-specific polymerase chain reaction amplification of the nodc gene. intraspecific dna polymorphism was evaluated through the restriction endonucleas ... | 2007 | 17899266 |
| chromosomal and symbiotic relationships of rhizobia nodulating medicago truncatula and m. laciniata. | multilocus sequence typing (mlst) is a sequence-based method used to characterize bacterial genomes. this method was used to examine the genetic structure of medicago-nodulating rhizobia at the amra site, which is located in an arid region of tunisia. here the annual medics medicago laciniata and m. truncatula are part of the natural flora. the goal of this study was to identify whether distinct chromosomal groups of rhizobia nodulate m. laciniata because of its restricted requirement for specif ... | 2007 | 17921275 |
| orotate phosphoribosyltransferase from corynebacterium ammoniagenes lacking a conserved lysine. | the pyre gene, encoding orotate phosphoribosyltransferase (oprtase), was cloned by nested pcr and colony blotting from corynebacterium ammoniagenes atcc 6872, which is widely used in nucleotide production. sequence analysis shows that there is a lack of an important conserved lysine (lys 73 in salmonella enterica serovar typhimurium oprtase) in the c. ammoniagenes oprtase. this lysine has been considered to contribute to the initiation of catalysis. the enzyme was overexpressed and purified from ... | 2007 | 17921291 |
| influence of the poly-3-hydroxybutyrate (phb) granule-associated proteins (phap1 and phap2) on phb accumulation and symbiotic nitrogen fixation in sinorhizobium meliloti rm1021. | sinorhizobium meliloti cells store excess carbon as intracellular poly-3-hydroxybutyrate (phb) granules that assist survival under fluctuating nutritional conditions. phb granule-associated proteins (phasins) are proposed to regulate phb synthesis and granule formation. although the enzymology and genetics of phb metabolism in s. meliloti have been well characterized, phasins have not yet been described for this organism. comparison of the protein profiles of the wild type and a phb synthesis mu ... | 2007 | 17921298 |
| h2o2 is required for optimal establishment of the medicago sativa/sinorhizobium meliloti symbiosis. | the symbiotic interaction between medicago sativa and sinorhizobium meliloti rmkatb(++) overexpressing the housekeeping catalase katb is delayed, and this delay is combined with an enlargement of infection threads. this result provides evidence that h(2)o(2) is required for optimal progression of infection threads through the root hairs and plant cell layers. | 2007 | 17921312 |
| using an ecophysiological analysis to dissect genetic variability and to propose an ideotype for nitrogen nutrition in pea. | nitrogen nutrition of legumes, which relies both on atmospheric n2 and soil mineral n, remains a major limiting factor of growth. a decade ago, breeders tried to increase n uptake through hypernodulation. despite their high nodule biomass, hypernodulating mutants were never shown to accumulate more nitrogen than wild types; they even generally displayed depressed shoot growth. the aim of this study was to dissect genetic variability associated with n nutrition in relation to c nutrition, using a ... | 2007 | 17921490 |
| metabolic reconstruction and modeling of nitrogen fixation in rhizobium etli. | rhizobiaceas are bacteria that fix nitrogen during symbiosis with plants. this symbiotic relationship is crucial for the nitrogen cycle, and understanding symbiotic mechanisms is a scientific challenge with direct applications in agronomy and plant development. rhizobium etli is a bacteria which provides legumes with ammonia (among other chemical compounds), thereby stimulating plant growth. a genome-scale approach, integrating the biochemical information available for r. etli, constitutes an im ... | 2007 | 17922569 |
| human selection and the relaxation of legume defences against ineffective rhizobia. | enforcement mechanisms are thought to be important in maintaining mutualistic cooperation between species. a clear example of an enforcement mechanism is how legumes impose sanctions on rhizobial symbionts that fail to provide sufficient fixed n2. however, with domestication and breeding in high-soil-n environments, humans may have altered these natural legume defences and reduced the agricultural benefits of the symbiosis. using six genotypes of soya beans, representing 60 years of breeding, we ... | 2007 | 17939985 |
| application of physical and genetic map of rhizobium leguminosarum bv. trifolii ta1 to comparison of three closely related rhizobial genomes. | a combined physical and genetic map of rhizobium leguminosarum biovar trifolii ta1 (rtta1) genome was constructed and used in comparison of chromosomal organization with the closely related r. leguminosarum bv. viciae 3841 (rlv) and rhizobium etli cnf42 (rhe). this approach allowed evaluation of chromosome and genome plasticity and provided important insights into r. leguminosarum lineage diversity. mssi, smii, paci, and i-ceui restriction endonucleases were chosen for the analysis, generating f ... | 2008 | 17960422 |