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isolation and expression of the bradyrhizobium japonicum adenylate cyclase gene (cya) in escherichia coli.a 5.0-kilobase-pair hindiii fragment of bradyrhizobium japonicum dna containing the cya gene which encodes adenylate cyclase was isolated as an insert in pbr322, using marker rescue of the maltose-negative phenotype of an escherichia coli cya mutant for identification. the isolated b. japonicum dna fragment was capable of reversing the pleiotropic phenotype of cya mutations when inserted in either orientation in the hindiii site of pbr322. the complemented e. coli strains produced high levels of ...19846090388
physical organization of the bradyrhizobium japonicum nitrogenase gene region.in bradyrhizobium japonicum usda 110 the three genes that encode the nitrogenase enzyme complex are separated into two transcription units, nifh and nifdk. we have physically mapped a 33-kilobase-pair region of the b. japonicum genome that contains both nifh and nifdk. the nifdk operon is located transcriptionally upstream from nifh, and all three genes are transcribed in the same direction. within the 20-kilobase-pair region that separates the promoters for these two transcription units, we hav ...19846090394
characterization of the gene encoding glutamine synthetase i (glna) from bradyrhizobium japonicum.we have isolated the bradyrhizobium japonicum gene encoding glutamine synthetase i (glna) from a phage lambda library by using a fragment of the escherichia coli glna gene as a hybridization probe. the rhizobial glna gene has homology to the e. coli glna gene throughout the entire length of the gene and can complement an e. coli glna mutant when borne on an expression plasmid in the proper orientation to be transcribed from the e. coli lac promoter. high levels of glutamine synthetase activity c ...19852859270
isolation and characterization of the dna region encoding nodulation functions in bradyrhizobium japonicum.the dna region encoding early nodulation functions of bradyrhizobium japonicum 3i1b110 (i110) was isolated by its homology to the functionally similar region from rhizobium meliloti. isolation of a number of overlapping recombinant clones from this region allowed the construction of a restriction map of the region. the identified nodulation region of b. japonicum shows homology exclusively to those regions of r. meliloti and rhizobium leguminosarum dna known to encode early nodulation functions. ...19852999080
molecular and immunological comparison of membrane-bound, h2-oxidizing hydrogenases of bradyrhizobium japonicum, alcaligenes eutrophus, alcaligenes latus, and azotobacter vinelandii.the membrane-bound hydrogenases of bradyrhizobium japonicum, alcaligenes eutrophus, alcaligenes latus, and azotobacter vinelandii were purified extensively and compared. sodium dodecyl sulfate-polyacrylamide gel electrophoresis of each hydrogenase revealed two prominent protein bands, one near 60 kilodaltons and the other near 30 kilodaltons. the migration distances during nondenaturing polyacrylamide gel electrophoresis were similar for all except a. vinelandii hydrogenase, which migrated furth ...19854008438
conservation of symbiotic nitrogen fixation gene sequences in rhizobium japonicum and bradyrhizobium japonicum.southern hybridization with nif (nitrogen fixation) and nod (nodulation) dna probes from rhizobium meliloti against intact plasmid dna of rhizobium japonicum and bradyrhizobium japonicum strains indicated that both nif and nod sequences are on plasmid dna in most r. japonicum strains. an exception is found with r. japonicum strain usda194 and all b. japonicum strains where nif and nod sequences are on the chromosome. in r. japonicum strains, with the exception of strain usda205, both nif and nod ...19854008441
chemotaxis to aromatic and hydroaromatic acids: comparison of bradyrhizobium japonicum and rhizobium trifolii.rhizobia are bacteria well known for their ability to fix nitrogen in symbiosis with leguminous plants. members of diverse rhizobial species grow at the expense of hydroaromatic and aromatic compounds commonly found in plant cells and plant litter. using a quantitative capillary assay to measure chemotaxis, we tested the ability of hydroaromatic acids, selected aromatic acids, and their metabolites to serve as chemoattractants for two distantly related rhizobial species, bradyrhizobium japonicum ...19854019407
anaerobic growth and denitrification among different serogroups of soybean rhizobia.we screened soybean rhizobia originating from three germplasm collections for the ability to grow anaerobically in the presence of no(3) and for differences in final product formation from anaerobic no(3) metabolism. denitrification abilities of selected strains as free-living bacteria and as bacteroids were compared. anaerobic growth in the presence of no(3) was observed in 270 of 321 strains of soybean rhizobia. all strains belonging to the 135 serogroup did not grow anaerobically in the prese ...198516346767
relationship between ureide n and n(2) fixation, aboveground n accumulation, acetylene reduction, and nodule mass in greenhouse and field studies with glycine max l. (merr).the relationship between ureide n and n(2) fixation was evaluated in greenhouse-grown soybean (glycine max l. merr.) and lima bean (phaseolus lunatus l.) and in field studies with soybean. in the greenhouse, plant n accumulation from n(2) fixation in soybean and lima bean correlated with ureide n. in soybean, n(2) fixation, ureide n, acetylene reduction, and nodule mass were correlated when n(2) fixation was inhibited by applying kno(3) solutions to the plants. the ureide-n concentrations of dif ...198516664027
decreased exopolysaccharide synthesis by anaerobic and symbiotic cells of bradyrhizobium japonicum.experiments were conducted to determine whether symbiotic bacteroids of bradyrhizobium japonicum produce exopolysaccharide within soybean (glycine max [l.] merr. cv ;lee 74') nodules. b. japonicum strains rt2, a derivative of usda 110 with resistance to streptomycin and rifampicin, and rt176-1, a mutant deficient in exopolysaccharide synthesis, were used. although aerobically cultured rt2 produced 1550 micrograms of exopolysaccharide per 10(10) cells, root nodules formed by rt2 contained only 55 ...198516664430
isolation and characterization of nodulation genes from bradyrhizobium sp. (vigna) strain irc 78.an 11.76-kilobase-pair (kb) segment of dna from bradyrhizobium sp. (vigna) strain irc 78 that hybridizes to nodulation genes of rhizobium meliloti strain 41 was isolated. hybridization of the 11.76-kb dna fragment to dna from other bradyrhizobium species revealed a high degree of sequence conservation in this region. transfer of the 11.76-kb segment to nodulation-defective (nod(-)) mutants of r. meliloti restored their ability to induce nodules on medicago sativa (alfalfa). mutants of strain irc ...198516593624
bacterial delta-aminolevulinic acid synthase activity is not essential for leghemoglobin formation in the soybean/bradyrhizobium japonicum symbiosis.previous studies of legume nodules have indicated that formation of the heme moiety of leghemoglobin is a function of the bacterial symbiont. we now show that a hema mutant of bradyrhizobium japonicum that cannot carry out the first step in heme biosynthesis forms fully effective nodules on soybeans. the bacterial mutant strain was constructed by first isolating the wild-type hema gene encoding delta-aminolevulinic acid synthase (ec 2.3.1.37) from a cosmid library, using a fragment of the rhizob ...198616593670
bioluminescence in soybean root nodules: demonstration of a general approach to assay gene expression in vivo by using bacterial luciferase.two plasmid vectors pfit001 and ppale001, containing luxab genes encoding bacterial luciferase [alkanal, reduced-fmn:oxygen oxidoreductase (1-hydroxylating, luminescing), ec 1.14.14.3] from vibrio harveyi, have been constructed. escherichia coli carrying derivatives of pfit001 with dna inserts in the unique ecori site located in luxb form "dark" colonies that can be readily distinguished from the bioluminescent or "bright" colonies. in contrast, promoterless ppale001 is used as a promoter-search ...198616593783
enzymes of alpha,alpha-trehalose metabolism in soybean nodules.metabolism of trehalose, alpha,d-glucopyranosyl-alpha,d-glucopyranoside, was studied in nodules of bradyrhizobium japonicum-glycine max [l.] merr. cv beeson 80 symbiosis. the nodule extract was divided into three fractions: bacteroid soluble protein, bacteroid fragments, and cytosol. the bacteroid soluble protein and cytosol fractions were gel-filtered. the key biosynthetic enzyme, trehalose-6-phosphate synthetase, was consistently found only in the bacteroids. trehalose-6-phosphate phosphatase ...198616664852
two indirect methods for detecting ureide synthesis by nodulated legumes.two methods were developed for the detection of altered ureide metabolism in legume nodules. both techniques are based on the positive correlation between the presence of high xanthine dehydrogenase (ec 1.2.1.37) specific activity in nodules and the ability of those nodules to produce the ureides, allantoin and allantoic acid. in the first method, nodulated legumes are treated for 2 weeks with a soil drench of allopurinol. after allopurinol treatment, leaves of n(2)-fed, ureide-producing legumes ...198616664857
regulation of the soybean-rhizobium nodule symbiosis by shoot and root factors.the availability of soybean mutants with altered symbiotic properties allowed an investigation of the shoot or root control of the relevant phenotype. by means of grafts between these mutants and wild-type plants (cultivar bragg and williams), we demonstrated that supernodulation as well as hypernodulation (nitrate tolerance in nodulation and lack of autoregulation) is shoot controlled in two mutants (nts382 and nts1116) belonging most likely to two separate complementation groups. the supernodu ...198616665072
the pleiotropic nature of symbiotic regulatory mutants: bradyrhizobium japonicum nifa gene is involved in control of nif gene expression and formation of determinate symbiosis.in the slow-growing soybean symbiont, bradyrhizobium japonicum (strain 110), a nifa-like regulatory gene was located immediately upstream of the previously mapped fixa gene. by interspecies hybridization and partial dna sequencing the gene was found to be homologous to nifa from klebsiella pneumoniae and rhizobium meliloti, and to a lesser extent, also to ntrc from k. pneumoniae. the b. japonicum nifa gene product was shown to activate b. japonicum and k. pneumoniae nif promoters (using nif::lac ...198615966104
rhizobins, a group of peptides in the free-amino-acid pool of the soybean-rhizobium system.free-living rhizobium (according to bergey's manual of systematic bacteriology, [1984, the williams & wilkins co., baltimore], bradyrhizobium) japonicum was found to release a peptide into the nutrient media. soybean nodules contained this peptide and exuded it into the soil. the name "rhizobin a" is suggested for this peptide. nodules also contained another peptide, rhizobin b, as well as an unidentified, ninhydrin-positive compound, rhizobin c. the three peptides were confined to the free-amin ...198616347004
restriction endonuclease and nif homology patterns of bradyrhizobium japonicum usda 110 derivatives with and without nitrogen fixation competence.dnas from bradyrhizobium japonicum usda 110 derivatives that differ in nitrogen-fixing ability produced similar electrophoretic patterns with five different restriction enzymes. our data support the hypothesis of common ancestry for these derivatives. derivatives i-110 and l1-110 differed as much as 100-fold in acetylene reduction activity when they were tested with several soybean cultivars in both greenhouse and field experiments. while possessing nodulating ability, derivative l1-110 is defic ...198616347007
identification of bradyrhizobium japonicum nodule isolates from wisconsin soybean farms.one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis was a more discriminating method than serotyping for identifying strains of bradyrhizobium japonicum. analysis of 543 nodule isolates from southeastern wisconsin soybean farms revealed that none of the isolates were formed by any of the inoculant strains supplied by either of two inoculant companies. twenty-nine indigenous strains and six inoculant strains were identified. strain 61a76, the most competitive indigenous stra ...198616347009
improved method of typing bradyrhizobium japonicum in soybean nodules.an improved method for antibiotic resistance recovery of bradyrhizobium japonicum from soybean (glycine max (l.) merr.) nodules that is simple, time saving, and economical was developed. this technique involves the use of two 96-well microtiter plates as a multinodule sterilization chamber and a template and a third plate as a 16-point replicator constructed with steel nails affixed to the plate with epoxy cement. with this system a team of four technicians could type 3,000 nodules per day. this ...198616347035
asymbiotic acetylene reduction by a fast-growing cowpea rhizobium strain with nitrogenase structural genes located on a symbiotic plasmid.a procedure was designed which enabled the detection of ex planta nitrogenase activity in the fast-growing cowpea rhizobium strain ihp100. nitrogenase activity in agar culture under air occurred at a rate similar to that found for bradyrhizobium strain cb756 but lower than that for rhizobium strain ors571. hybridization studies showed that both nod and nif genes were located on a 410-kilobase sym plasmid in strain ihp100.198616347045
symbiotic effectiveness and host-strain interactions of rhizobium fredii usda 191 on different soybean cultivars.nodulation, acetylene reduction activity, dry matter accumulation, and total nitrogen accumulation by nodulated plants growing in a nitrogen-free culture system were used to compare the symbiotic effectiveness of the fast-growing rhizobium fredii usda 191 with that of the slow-growing bradyrhizobium japonicum usda 110 in symbiosis with five soybean (glycine max (l.) merr.) cultivars. measurement of the amount of nitrogen accumulated during a 20-day period of vegetative growth (28 to 48 days afte ...198616347066
bradyrhizobium japonicum serocluster 123 and diversity among member isolates.diversity was examined within a group of 79 isolates of bradyrhizobium japonicum reactive to fluorescent antibodies (fas) prepared against b. japonicum usda 123. analyses were by means of cross-adsorbed fas, bacteriophage typing, and endonuclease restriction digest patterns. serogroups 127 and 129 shared antigenic determinants with serogroup 123 but not with each other. bacteriophage and dna digest patterns reflected more common features between serogroups 123 and 127 than between 123 and 129. s ...198616347079
role of pili (fimbriae) in attachment of bradyrhizobium japonicum to soybean roots.pili (fimbriae) were observed on cells of each of the five strains of bradyrhizobium japonicum and the one strain of rhizobium trifolii examined. pili on b. japonicum were about 4 nm in diameter and polarly expressed. piliated cells were estimated by transmission electron microscopy and hydrophobic attachment to polystyrene to constitute only a small percentage of the total population. the proportion of piliated cells in these populations was dependent on culture age in some strains. piliated b. ...198616347100
analysis of the symbiotic performance of bradyrhizobium japonicum usda 110 and its derivative i-110 and discovery of a new mannitol-utilizing, nitrogen-fixing usda 110 derivative.previously, bradyrhizobium japonicum usda 110 was shown to contain colony morphology variants which differed in nitrogen-fixing ability. mannitol-utilizing derivatives l1-110 and l2-110 have been shown to be devoid of symbiotic nitrogen fixation ability, and non-mannitol-utilizing derivatives i-110 and s-110 have been shown to be efficient at nitrogen fixation. the objectives of this study were to determine the effect of media carbon sources on the symbiotic n(2)-fixing ability of strain usda 11 ...198616347117
characterization of a mannitol-utilizing, nitrogen-fixing bradyrhizobium japonicum usda 110 derivative.we have isolated a colonial derivative of bradyrhizobium japonicum usda 110 (designated mn-110) that is both mannitol utilizing and n(2) fixing. derivative mn-110 showed growth on mannitol and glucose similar to that of non-n(2)-fixing, mannitol-utilizing l2-110. derivative mn-110 showed high constitutive and induced d-mannitol dehydrogenase activity (similar to l2-110) relative to n(2)-fixing, non-mannitol-utilizing i-110. hybridization to ecori and hindiii total dna digests with cloned usda 11 ...198616347118
bacterial growth rates and competition affect nodulation and root colonization by rhizobium meliloti.the addition of streptomycin to nonsterile soil suppressed the numbers of bacterial cells in the rhizosphere of alfalfa (medicago sativa l.) for several days, resulted in the enhanced growth of a streptomycin-resistant strain of rhizobium meliloti, and increased the numbers of nodules on the alfalfa roots. a bacterial mixture inoculated into sterile soil inhibited the colonization of alfalfa roots by r. meliloti, caused a diminution in the number of nodules, and reduced plant growth. enterobacte ...198616347173
rapid colored-nodule assay for assessing root exudate-enhanced competitiveness of bradyrhizobium japonicum.the effects of root exudate (re) treatment on nodule occupancy by bradyrhizobium japonicum were investigated by a rapid colored-nodule assay, which is based on the observation that b. japonicum l-110 and its antibiotically marked derivatives form dark-red nodules on certain soybean (glycine max) cultivars, whereas other strains form beige nodules. the efficacy of the assay was confirmed by direct immunofluorescence and by antibiotic platings of nodule bacteria. both logarithmic- and stationary-p ...198616347177
fractionation and estimation of particle-attached and unattached bradyrhizobium japonicum strains in soils.rhizobial cells attached or unattached to soil particles were estimated. nonsterile soils into which antibiotic-resistant mutants of bradyrhizobium japonicum had been introduced were fractionated by a centrifugation technique into two fractions: a, which contained mainly rhizobial cells attached to soil particles, and f, which contained mainly rhizobial cells unattached to them. rhizobial counts decreased in both fractions during incubation of the soil at 30 degrees c, with a concomitant decreas ...198616347182
growth of fast- and slow-growing rhizobia on ethanol.free-living soybean rhizobia and bradyrhizobium spp. (lupine) have the ability to catabolize ethanol. of the 30 strains of rhizobia examined, only the fast- and slow-growing soybean rhizobia and the slow-growing bradyrhizobium sp. (lupine) were capable of using ethanol as a sole source of carbon and energy for growth. two strains from each of the other rhizobium species examined (r. meliloti, r. loti, and r. leguminosarum biovars phaseoli, trifolii, and viceae) failed to grow on ethanol. one rhi ...198616347190
enrichment for hydrogen-oxidizing acinetobacter spp. in the rhizosphere of hydrogen-evolving soybean root nodules.field soybean plants were inoculated with hup wild-type or h(2) uptake-negative (hup) mutants of bradyrhizobium japonicum. for two consecutive summers we found an enrichment for acinetobacters associated with the surfaces of the h(2)-evolving nodules. soybean root nodules that evolved h(2) had up to 12 times more acinetobacter spp. bacteria associated with their surfaces than did nodules incapable of evolving h(2). all of the newly isolated strains identified as acinetobacter obtained from the s ...198616347197
evaluation of diverse antisera, conjugates, and support media for detecting bradyrhizobium japonicum by indirect enzyme-linked immunosorbent assay.we evaluated three antisera and four enzyme conjugates for the detection of bradyrhizobium japonicum by an indirect enzyme-linked immunosorbent assay in microtiter plates. nitrocellulose membrane sheets were then evaluated as an alternative support medium by using some combinations. partially purified immunoglobulin g (igg) or unpurified antisera to strain usda 110 raised in rabbits, goats, or sheep was reacted in microtiter plates with alkaline phosphatase conjugated to protein a, goat anti-rab ...198616347212
effects of k+ on the proton motive force of bradyrhizobium sp. strain 32h1.in previous studies, respiring bradyrhizobium sp. strain 32h1 cells grown under 0.2% o2, conditions that derepress n2 fixation, were found to have a low proton motive force of less than -121 mv, because of a low membrane potential (delta psi). in contrast, cells grown under 21% o2, which do not fix n2, had high proton motive force values of -175 mv or more, which are typical of respiring bacteria, because of high delta psi values. in the present study, we found that a delta psi of 0 mv in respir ...19863009414
genetic locus in rhizobium japonicum (fredii) affecting soybean root nodule differentiation.a genetic locus in fast-growing rhizobium japonicum (fredii) usda 191 (fix+ on several contemporary soybean cultivars) was identified by random tn5 mutagenesis as affecting the development and differentiation of root nodules. this mutant (mu042) is prototrophic and shows no apparent alterations in its surface properties. it induces aberrant nodules, arrested at the same early level of differentiation, on all its host plants. an 8.1-kilobase ecori fragment containing tn5 was cloned from mu042. in ...19863009416
two-component regulatory systems responsive to environmental stimuli share strongly conserved domains with the nitrogen assimilation regulatory genes ntrb and ntrc.we report that the ntrb and ntrc proteins of bradyrhizobium sp. [parasponia] strain rp501 share homology with other regulatory proteins. there is extensive conservation of c-terminal regions between products of rp501 ntrb; klebsiella pneumoniae ntrb; escherichia coli envz, cpxa, and phor; agrobacterium tumefaciens vira; and, to a lesser extent, e. coli chea. there is also extensive conservation of n-terminal regions between products of rp501 ntrc; k. pneumoniae ntrc; e. coli ompr, sfra, phob, ch ...19863020561
activation of the bradyrhizobium japonicum nifh and nifdk operons is dependent on promoter-upstream dna sequences.previous analysis of b. japonicum nifh'- and nifd'-'lacz translational fusions showed that these promoters could be activated by the k. pneumoniae nifa plus the e. coli ntra gene products. to study the functions of the dna 5' to these promoters, plasmids carrying deletions in this region were constructed and analyzed in vivo in a heterologous system consisting of an e. coli (ntra+) background with a plasmid that constitutively expresses the k. pneumoniae nifa gene. activation of the b. japonicum ...19863086837
organization and characterization of genes essential for symbiotic nitrogen fixation from bradyrhizobium japonicum i110.a total of 96 independent tn5 insertions within a 39-kilobase-pair (kbp) segment of chromosomal dna containing the three structural genes for nitrogenase (nifh, nifd, and nifk) from bradyhizobium japonicum i110 were obtained in escherichia coli and transferred to the wild-type strain by marker exchange. individual transconjugants containing a tn5 insertion were inoculated onto glycine max cv. wilkin (soybeans) and analyzed for their effect on symbiotic nitrogen fixation. in addition to the three ...19863462181
nitrogenase promoter-lacz fusion studies of essential nitrogen fixation genes in bradyrhizobium japonicum i110.dna fragments containing either the nifd or nifh promoter and 5' structural gene sequences from bradyrhizobium japonicum i110 were fused in frame to the lacz gene. stable integration of these nif promoter-lacz fusions by homologous double reciprocal crossover into a symbiotically nonessential region of the b. japonicum chromosome provided an easy assay for the effects of potential nif regulatory mutants. the level of beta-galactosidase activity expressed from these two nif promoter-lacz fusions ...19863462182
cloning and expression of bradyrhizobium japonicum uptake hydrogenase structural genes in escherichia coli.to identify the structural genes for the components of bradyrhizobium japonicum uptake hydrogenase (mr 60,000 and 30,000), we have expressed these genes in escherichia coli and shown that the products cross-react with antibodies to the respective hydrogenase subunits. we constructed subclones of overlapping dna fragments from an uptake hydrogenase-complementing cosmid, phu52 [lambert, g. r., cantrell, m. a., hanus, f. j., russell, s. a., haddad, k. r. & evans, h. j. (1985) proc. natl. acad. sci. ...19863532119
effect of lectin on nodulation by wild-type bradyrhizobium japonicum and a nodulation-defective mutant.the nodulation characteristics of wild-type bradyrhizobium japonicum usda 110 and mutant strain hs111 were examined. mutant strain hs111 exhibits a delayed-nodulation phenotype, a result of its inability to initiate successful nodulation promptly following inoculation of the soybean root. previously, we showed that the defect in initiation of infection leading to subsequent nodulation which is found in hs111 can be phenotypically reversed by pretreatment with soybean root exudate or soybean seed ...19863707122
enzymes of the beta-ketoadipate pathway are inducible in rhizobium and agrobacterium spp. and constitutive in bradyrhizobium spp.protocatechuate is a universal growth substrate for members of the family rhizobiaceae, and these bacteria utilize the aromatic compound via the beta-ketoadipate pathway. this report describes transcriptional controls exercised by different subgroups of the rhizobiaceae over five enzymes that catalyze consecutive reactions in the pathway: protocatechuate oxygenase (ec 1.13.11.3), beta-carboxy-cis,cis-muconate lactonizing enzyme (ec 5.5.1.2), gamma-carboxymuconolactone decarboxylase (ec 4.1.1.44) ...19863941043
conserved nodulation genes from the non-legume symbiont bradyrhizobium sp. (parasponia).a nodulation locus from the broad-host-range, non-legume symbiont bradyrhizobium sp. (parasponia) strain anu289, has been identified by hybridisation to cloned rhizobium trifolii nodulation (nod) genes. transfer of cloned anu289 nod genes to r.trifolii nodulation-deficient mutants showed that the locus contains a functional homologue of the r. trifolii nodd gene. dna sequence analysis revealed the presence of three additional genes noda, nodb and nodc clustered adjacent to nodd. the four genes f ...19863960737
cell surface polysaccharides from bradyrhizobium japonicum and a nonnodulating mutant.the cell surface polysaccharides of wild-type bradyrhizobium japonicum usda 110 and a nonnodulating mutant, strain hs123, were analyzed. the capsular polysaccharide (cps) and exopolysaccharide (eps) of the wild type and the mutant strain do not differ in their sugar composition. cps and eps are composed of mannose, 4-o-methylgalactose/galactose, glucose, and galacturonic acid in a ratio of 1:1:2:1, respectively. h nuclear magnetic resonance spectra of the eps and cps of the wild type and mutant ...19873793715
nodulin-26, a peribacteroid membrane nodulin is expressed independently of the development of the peribacteroid compartment.the peribacteroid membrane (pbm) of root nodules is derived from the plant cell plasma membrane but contains in addition several nodule-specific host proteins (nodulins). antibodies raised against purified pbm of soybean were used to immunoprecipitate polysomes to isolate an rna fraction that served as a template for the synthesis of a cdna probe for screening a nodule-specific cdna library. clone p1b1 was found to encode a 26.5 kda polypeptide (nodulin-26) which is immunoprecipitable specifical ...19873822816
nickel uptake in bradyrhizobium japonicum.free-living bradyrhizobium japonicum grown heterotrophically with 1 microm 63ni2+ accumulated label. strain sr470, a hupc mutant, accumulated almost 10-fold more 63ni2+ on a per-cell basis than did strain sr, the wild type. nongrowing cells were also able to accumulate nickel over a 2-h period, with the hupc mutant strain sr470 again accumulating significantly more 63ni2+ than strain sr. these results suggest that this mutant is constitutive for nickel uptake as well as for hydrogenase expressio ...19873558318
a locus encoding host range is linked to the common nodulation genes of bradyrhizobium japonicum.by using cloned rhizobium meliloti, rhizobium leguminosarum, and rhizobium sp. strain mpik3030 nodulation (nod) genes as hybridization probes, homologous regions were detected in the slow-growing soybean symbiont bradyrhizobium japonicum usda 110. these regions were found to cluster within a 25-kilobase (kb) region. specific nod probes from r. meliloti were used to identify noda-, nodb-, nodc-, and nodd-like sequences clustered on two adjacent hindiii restriction fragments of 3.9 and 5.6 kb. a 7 ...19873584066
structure of the bradyrhizobium japonicum gene hema encoding 5-aminolevulinic acid synthase.the nucleotide (nt) sequence of the hema gene, which encodes 5-aminolevulinic acid synthase (alas) from the bacterium bradyrhizobium japonicum, is presented. this sequence predicts a protein of 408 amino acids (aa) with an mr of 44,599. this predicted amino acid sequence is highly homologous to that of the chicken embryonic liver alas, exhibiting a 48.8% identical amino acid sequence over the entire length of the bacterial protein. a single mrna start point was demonstrated by s1 protection anal ...19873609750
mapping and nucleotide sequence of the nifs promoter of bradyrhizobium japonicum. 19873684606
bradyrhizobium japonicum mutants defective in nitrogen fixation and molybdenum metabolism.bradyrhizobium japonicum jh mutants deficient in molybdenum metabolism into the enzymes nitrogenase and nitrate reductase were isolated by using the vector psup1011, which carries transposon tn5 (streptomycin and kanamycin resistance). mutants in mo metabolism were obtained at a frequency of 3.6 x 10(-3) (per kan strr colony). the mutants were detected by their poor ability to grow in nitrate-containing medium without added mo. one of the mutant types required 10(5) times more molybdate than the ...19873473063
variability in molybdenum uptake activity in bradyrhizobium japonicum strains.twenty naturally occurring strains of bradyrhizobium japonicum in 11 serogroups were screened for the ability to take up mo as bacteroids from soybean root nodules. the strains varied greatly in their ability to take up mo in a 1-min period. the best strain was usda 136, which had an mo uptake activity of almost 3.0 pmol/min per mg of bacteroid (dry weight). in contrast, the poorest strain, usda 62, had an mo uptake activity of 0.35 pmol of mo per min per mg of bacteroid. there were similarities ...19873473064
bacterial heme synthesis is required for expression of the leghemoglobin holoprotein but not the apoprotein in soybean root nodules.in bradyrhizobium japonicum/soybean symbiosis, the leghemoglobin (legume hemoglobin) apoprotein is a plant product, but the origin of the heme prosthetic group is not known. b. japonicum strain lo505 is a transposon tn5-induced cytochrome-deficient mutant; it excreted the oxidized heme precursor coproporphyrin iii into the growth medium. mutant strain lo505 was specifically deficient in protoporphyrinogen oxidase (protoporphyrinogen-ix:oxygen oxidoreductase, ec 1.3.3.4) activity, and thus it cou ...19873479799
expression of uptake hydrogenase and hydrogen oxidation during heterotrophic growth of bradyrhizobium japonicum.strains i-110 ars, sr, usda 136, usda 137, and ak13 1c of bradyrhizobium japonicum induced hup activity when growing heterotrophically in medium with carbon substrate and nh4cl in the presence of 2% h2 and 2% o2. hup activity was induced during heterotrophic growth in the presence of carbon substrates, which were assimilated during the time of h2 oxidation. strains i-110 ars and sr grown heterotrophically or chemoautotrophically for 3 days had similar rates of h2 oxidation. similar rates of hup ...19873115959
analysis of lectin binding by bradyrhizobium japonicum strains grown on nitrocellulose filters using peroxidase-labeled lectin.a procedure was developed to assess the ability of wild-type and mutant strains of bradyrhizobium japonicum to bind soybean lectin. the lectin-binding ability of bacteria grown on nitrocellulose filters was determined using peroxidase-labeled soybean lectin. the assay produced clear differences between strains known to be unable to bind soybean lectin and those which can. the assay gave results identical to those of the fluorescein isothiocyanate-soybean lectin-binding assay of t. v. bhuvaneswar ...19873118739
involvement of glutamate in the respiratory metabolism of bradyrhizobium japonicum bacteroids.bradyrhizobium japonicum bacteroids were isolated anaerobically and supplied with 14c-labeled succinate, malate, aspartate, or glutamate for periods of up to 60 min in the presence of myoglobin to control the o2 concentration. succinate and malate were absorbed about twice as rapidly as glutamate and aspartate. conversion of substrate to co2 was most rapid for malate, followed by succinate, glutamate, and aspartate. when co2 production was expressed as a proportion of total carbon taken up, mala ...19872879829
identification and characterization of the rhizobium meliloti ntrc gene: r. meliloti has separate regulatory pathways for activation of nitrogen fixation genes in free-living and symbiotic cells.we show here that rhizobium meliloti, the nitrogen-fixing endosymbiont of alfalfa (medicago sativa), has a regulatory gene that is structurally homologous to previously characterized ntrc genes in enteric bacteria. dna sequence analysis showed that r. meliloti ntrc is homologous to previously sequenced ntrc genes from klebsiella pneumoniae and bradyrhizobium sp. (parasponia) and that an ntrb-like gene is situated directly upstream from r. meliloti ntrc. similar to its counterparts in k. pneumoni ...19872881918
acetoacetyl-coa thiolase of bradyrhizobium japonicum bacteroids: purification and properties.acetoacetyl-coa thiolase of bradyrhizobium japonicum bacteroids has been purified greater than 130-fold. the enzyme has a molecular weight of 180,000 +/- 15,000 and consists of four identical subunits of 44,000 +/- 2,000. the enzyme was specific for acetoacetyl-coa; ketodecanoyl-coa did not serve as a substrate. catalysis proceeds via a ping-pong mechanism. iodoacetamide effectively inhibited the enzyme but acetoacetyl-coa provided considerable protection against this compound. magnesium was fou ...19872883931
the symbiotic nitrogen fixation regulatory operon (fixrnifa) of bradyrhizobium japonicum is expressed aerobically and is subject to a novel, nifa-independent type of activation.the bradyrhizobium japonicum n2 fixation regulatory gene, nifa, was sequenced and its transcription start site determined. between the start of transcription and the nifa gene an open reading frame of 278 codons was found and named fixr. a deletion in fixr which allowed transcription into nifa resulted in a 50% reduced fix activity. the fixrnifa operon was expressed in soybean root nodules, in cultures grown anaerobically with nitrate as terminal electron acceptor, in microaerobic cultures, and ...19873313281
effect of ph on tritium exchange and hydrogen production and uptake in free-living cells and in bacteroids of bradyrhizobium japonicum.soybean nodule bacteroids and bradyrhizobium japonicum free-living cells induced for h2-uptake hydrogenase, actively catalyze the evolution of h2 in a reaction highly dependent on the ph. the optimal phs for the evolution and uptake reactions were 4.0 and 7.5-8.0, respectively. no differences were found between free-living cells and bacteroids with respect to hydrogen acceptor specificity, although absolute rates of h2 uptake were higher for free-living cells. both types of cells were able to ev ...19873322198
tn5-induced cytochrome mutants of bradyrhizobium japonicum: effects of the mutations on cells grown symbiotically and in culture.two bradyrhizobium japonicum cytochrome mutants were obtained by tn5 mutagenesis of strain lo and were characterized in free-living cultures and in symbiosis in soybean root nodules. one mutant strain, lo501, expressed no cytochrome aa3 in culture; it had wild-type levels of succinate oxidase activity but could not oxidize nadh or n,n,n',n'-tetramethyl-p-phenylenediamine (tmpd). the cytochrome content of lo501 root nodule bacteroids was nearly identical to that of the wild type, but the mutant e ...19873029019
genetic and structural analysis of the rhizobium meliloti fixa, fixb, fixc, and fixx genes.the fixa, fixb, fixc, and fixx genes of rhizobium meliloti 1021 constitute an operon and are required for nitrogen fixation in alfalfa nodules. dna homologous to the r. meliloti fixabc genes is present in all other rhizobium and bradyrhizobium species examined, but fixabc-homologous sequences were found in only one free-living diazotroph, azotobacter vinelandii. to determine whether the fixabcx genes share sequence homology with any of the 17 klebsiella pneumoniae nif genes, we determined the en ...19873029021
isolation and characterization of symbiotic mutants of bradyrhizobium sp. (arachis) strain nc92: mutants with host-specific defects in nodulation and nitrogen fixation.random transposon tn5 mutagenesis of bradyrhizobium sp. (arachis) strain nc92, a member of the cowpea cross-inoculation group, was carried out, and kanamycin-resistant transconjugants were tested for their symbiotic phenotype on three host plants: groundnut, siratro, and pigeonpea. two nodulation (nod- phenotype) mutants were isolated. one is unable to nodulate all three hosts and appears to contain an insertion in one of the common nodulation genes (nodabcd); the other is a host-specific nodula ...19873032910
inhibition of hydrogenase synthesis by dna gyrase inhibitors in bradyrhizobium japonicum.derepression of an uptake hydrogenase in bradyrhizobium japonicum is dependent on a microaerophilic environment. addition of dna gyrase inhibitors during depression of hydrogenase specifically prevented expression of the hydrogenase enzyme. antibodies to individual hydrogenase subunits failed to detect the protein after derepression in the presence of inhibitors, although there was no general inhibition of protein synthesis. the general pattern of proteins synthesized from 14c-labeled amino acid ...19873034865
a genetic locus essential for formate-dependent growth of bradyrhizobium japonicum.a genetic locus essential for the formate-dependent growth of bradyrhizobium japonicum was isolated by complementation of ethyl methanesulfonate-induced mutants with a cosmid gene library of b. japonicum dna. three related cosmids containing 18.7 kilobase pairs of b. japonicum dna in common were identified as being able to restore formate-dependent growth capability to mutants lacking either ribulosebisphosphate carboxylase or both ribulosebisphosphate carboxylase and phosphoribulokinase activit ...19873036781
transposon-induced symbiotic mutants of bradyrhizobium japonicum: isolation of two gene regions essential for nodulation.two strains of the soybean endosymbiont bradyrhizobium japonicum, usda 110 and 61 a101 c, were mutagenized with transposon tn5. after plant infection tests of a total of 6,926 kanamycin and streptomycin resistant transconjugants, 25 mutants were identified that are defective in nodule formation (nod-) or nitrogen fixation (fix-). seven nod- mutants were isolated from strain usda110 and from strain 61 a101 c, 4 nod- mutants and 14 fix- mutants were identified. subsequent auxotrophic tests on thes ...19873037278
differential transcription of the two glutamine synthetase genes of bradyrhizobium japonicum.bradyrhizobium japonicum induces the formation of nitrogen-fixing symbiotic root nodules on soybean plants. the b. japonicum genome encodes two isoforms of glutamine synthetase (gs). one form, gsi, encoded by the gene glna, is similar in structure and activity to the enzyme found in all other bacteria. the second form, gsii, encoded by glnii, is structurally related to the eucaryotic enzyme. genetic analyses indicate that glna or glnii alone is sufficient to provide glutamine prototrophy, wherea ...19872445733
long-term effects of metal-rich sewage sludge application on soil populations of bradyrhizobium japonicum.the application of sewage sludge to land may increase the concentration of heavy metals in soil. of considerable concern is the effect of heavy metals on soil microorganisms, especially those involved in the biocycling of elements important to soil productivity. bradyrhizobium japonicum is a soil bacterium involved in symbiotic nitrogen fixation with glycine max, the common soybean. to examine the effect of metal-rich sludge application on b. japonicum, the mics for pb, cu, al, fe, ni, zn, cd, a ...198716347281
symbiotic expression of cosmid-borne bradyrhizobium japonicum hydrogenase genes.the expression of cosmid-borne bradyrhizobium japonicum hydrogenase genes in alfalfa, clover, and soybean nodules harboring rhizobium transconjugants was studied. cosmid phu52 conferred hydrogen uptake (hup) activity in both free-living bacteria and in nodules on the different plant hosts, although in nodules the instability of the cosmid resulted in low levels of hup activity. in contrast, cosmid phu1, which does not confer hup activity on free-living bacteria, gave a hup phenotype in nodules o ...198716347291
influence of the bradyrhizobium japonicum hydrogenase on the growth of glycine and vigna species.the effect of the bradyrhizobium japonicum hydrogenase on nitrogen fixation was evaluated by comparing the growth of vigna and glycine species inoculated with a hup mutant and its hup revertant. in all experiments, the growth of plants inoculated with the strain without hydrogenase was at least equal to the growth of the strain with hydrogenase. for glycine usuriensis and glycine max cv. hodgson in liquid culture, the growth was higher with the hup strain. it is possible that reduced rates of ni ...198716347309
influence of 5-methyltryptophan-resistant bradyrhizobium japonicum on soybean root nodule indole-3-acetic acid content.bradyrhizobium japonicum mutants resistant to 5-methyltryptophan were isolated. some of these mutants were found to accumulate indole-3-acetic acid (iaa) and tryptophan in culture. in greenhouse studies, nodules from control plants inoculated with wild-type bradyrhizobia contained 0.04, 0.10, and 0.58 mug of free, ester-linked, and peptidyl iaa g (fresh weight) of nodules, respectively. nodules from plants inoculated with 5-methyltryptophan-resistant bradyrhizobia contained 0.94, 1.30, and 10.6 ...198716347335
bradyrhizobium japonicum-environment interactions: nodulation and interstrain competition in soils along an elevational transect.the effects of temperature and soil type on interstrain competition of bradyrhizobium japonicum and on nodulation and nitrogen accumulation in five soybean varieties belonging to four maturity groups were investigated at three sites devoid of soybean rhizobia along an elevational transect in hawaii. competition patterns of the three b. japonicum strains were unaffected by soil type or soil temperature. strain usda 110 was the best competitor, occupying on the average 81 and 64% of the nodules in ...198716347338
identification of lotus rhizobia by direct dna hybridization of crushed root nodules.hybridization of crushed lotus pedunculatus root nodules with p-labeled total genomic dna probes was used to identify rhizobium loti and bradyrhizobium sp. (lotus rhizobia). probes always hybridized with homologous target dna and frequently with dnas of other strains from the same genus. intergeneric hybridization did not occur. results were comparable to those from colony hybridization.198716347400
methods to alter the recovery and nodule location of bradyrhizobium japonicum inoculant strains on field-grown soybeans.three strains of bradyrhizobium japonicum, i17, 110, and 61a76, were evaluated for their ability to form nodules on field-grown soybeans in soil with a highly competitive indigenous b. japonicum population. the predominant indigenous strain, 0336, in the field site used was unlike the more common isolates from midwestern soils which belong to the 123 or 138 serogroups. this strain persisted in the soil for at least 30 years without any soybean crops. the three inoculant strains differed in their ...198716347401
serological relatedness of rhizobium fredii to other rhizobia and to the bradyrhizobia.several isolates of rhizobium fredii were examined for their serological relatedness to each other, to bradyrhizobium japonicum, and to other fast- and slow-growing rhizobia. immunofluorescence, agglutination, and immunodiffusion analyses indicated that r. fredii contains at least three separate somatic serogroups, usda 192, usda 194, and usda 205. there was no cross-reaction between any of the r. fredii isolates and 13 of the 14 b. japonicum somatic serogroups tested. cross-reactions were obtai ...198716347404
ecology of indigenous soil rhizobia: response of bradyrhizobium japonicum to readily available substrates.populations of indigenous bradyrhizobium japonicum serocluster 123 and serogroups 110 and 138 were studied after various sugars were added to their soil habitat. loam soil with approximately 10 cells of each group per g of soil were amended every 3 days with 0.1% glucose, sucrose, arabinose, xylose, or galactose. enumerations of the populations were made every 12 days by immunofluorescence assay. each b. japonicum population in the sugar-treated soils increased by about 1 log during the first 12 ...198716347412
transposon mutants of bradyrhizobium japonicum altered in attachment to host roots.transposon mutants of bradyrhizobium japonicum 110 ars were produced and screened for changes in attachment ability. mutant cfk4 produced twice as many piliated cells, attached in 2.5-fold-higher numbers to soybean root segments, and colonized roots in about 2-fold-higher numbers than did the parental strain, 110 ars. mutants cfk35 and cfk38 were reduced in their attachment about 2-fold and 3.5-fold, respectively. this corresponded to reductions in piliated cells in their populations, reduced re ...198716347421
mapping of a bradyrhizobium japonicum dna region carrying genes for symbiosis and an asymmetric accumulation of reiterated sequences.spontaneous kanamycin-sensitive derivatives were obtained from bradyrhizobium japonicum (strain 110) carrying tn5 insertions in symbiotic gene cluster i; the derivatives were shown to have deletions of cluster i plus flanking dna which was indicated by the absence of different copies of the repeated sequences rsalpha and rsbeta. the deletion endpoints were mapped using cloned wild-type dna fragments containing rsalpha copies which also served as origins for overlapped cosmid cloning. the majorit ...198716347445
conservation of a symbiotic dna region in soybean root nodule bacteria.bradyrhizobium japonicum usda 3i1b110 contains a dna region in which symbiotic genes and many repeated sequences are closely linked. hybridization analysis revealed that this region was highly conserved in some b. japonicum strains (usda 24, usda 122, usda 123, atcc 10324, 61a24) but not in others (usda 76, 61a76, 61a101). the genomic presence of multiple copies of one of the repeated sequences (rsalpha) appeared to be specifically characteristic for soybean root nodule bacteria, including the f ...198716347446
conserved plasmid hydrogen-uptake (hup)-specific sequences within huprhizobium leguminosarum strains.thirteen rhizobium leguminosarum strains previously reported as h(2)-uptake hydrogenase positive (hup) or negative (hup) were analyzed for the presence and conservation of dna sequences homologous to cloned bradyrhizobium japonicum hup-specific dna from cosmid phu1 (m. a. cantrell, r. a. haugland, and h. j. evans, proc. natl. acad. sci. usa 80:181-185, 1983). the hup phenotype of these strains was reexamined by determining hydrogenase activity induced in bacteroids from pea nodules. five strains ...198716347471
genetic diversity in bradyrhizobium japonicum serogroup 123 and its relation to genotype-specific nodulation of soybean.the genetic diversity among 20 field isolates of bradyrhizobium japonicum serogroup 123 was examined by using restriction endonuclease digestions, one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total cell proteins, southern hybridization analysis of nif and nod genes, and intrinsic antibiotic resistance profiles. all of the isolates were previously separated into three broad nodulation classes (low, medium, and high) based on their ability to form symbioses with spe ...198716347481
nodulation and competition for nodulation of selected soybean genotypes among bradyrhizobium japonicum serogroup 123 isolates.twenty recently obtained field isolates of bradyrhizobium japonicum serogroup 123 were tested for their nodule mass production on the standard commercial soybean (glycine max (l.) merr. cv. williams) and on two soybean plant introduction (pi) genotypes previously determined to restrict nodulation by strain usda 123. four of the field isolates showed similar restricted nodulation on the two genotypes, while all 20 isolates produced a normal amount of nodules on g. max cv. williams. serological an ...198716347482
variability in effectiveness of rhizobia during culture and in nodules.the ability of three strains of bradyrhizobium sp. (vigna) to fix dinitrogen in symbiotic association with siratro (macropitilium atropurpureum) was measured after culture in broth and after isolation from nodules. seven transfers were made between the initial broth culture and the final broth culture. a total of 40 single-colony isolates were obtained from cultures 1 and 7 to test effectiveness. variation in dinitrogen-fixing effectiveness of the population of one strain did not change on cultu ...198716347512
glutamine synthetase genes are regulated by ammonia provided externally or by symbiotic nitrogen fixation.glutamine synthetase is the key enzyme in the assimilation by plants of reduced nitrogen provided from either the soil or fixed symbiotically in association with rhizobium. we have isolated a number of cdna clones for soybean glutamine synthetase (gs) from a nodule-cdna library, using rna from polysomes immunoprecipitated by gs antibodies. transcripts corresponding to two clones differing in their 3' non-translated sequences were present in both root and nodule tissue; however, the concentration ...198716453762
the occurrence of phytoferritin and its relationship to effectiveness of soybean nodules.polyacrylamide gel electrophoresis and electron microscopy revealed that accumulation of iron-protein in soybean nodules is influenced by nodule age, mutation in bradyrhizobia, and rhizobial/bradyrhizobial strain-soybean cultivar interactions. iron-protein concentrations (micrograms per milligram protein) were inversely related to heme concentrations (nanomoles per milligram protein), with correlation coefficients (r values) ranging from -0.98 in young nodules to -0.83 in mature ones. bradyrhizo ...198716665240
uptake and metabolism of carbohydrates by bradyrhizobium japonicum bacteroids.bradyrhizobium japonicum bacteroids were isolated anaerobically and were supplied with (14)c-labeled trehalose, sucrose, udp-glucose, glucose, or fructose under low o(2) (2% in the gas phase). uptake and conversion of (14)c to co(2) were measured at intervals up to 90 minutes. of the five compounds studied, udp-glucose was most rapidly absorbed but it was very slowly metabolized. trehalose was the sugar most rapidly converted to co(2), and fructose was respired at a rate at least double that of ...198716665284
nitrate induced regulation of nodule formation in soybean.nodule formation was inhibited by exposing soybean plants to nitrate in plastic growth pouches. exposure to 15 millimolar nitrate resulted in a 2.5-fold decrease in the number of nodules formed in the region of the primary root above the mark made at the time of inoculation to indicate the position of the root tip. serial section analysis of bradyrhizobium infections in this region revealed that infection initiation was inhibited approximately 3-fold by exposure to nitrate. both initial cortical ...198716665428
responses of rj(1) and rj(1) soybean isolines to inoculation with bradyrhizobium japonicum.we evaluated the symbiotic phenotypes of nodulation-restrictive and normal soybean isolines by inoculating clark (genotypically rj(1)rj(1)) and mutant clark-rj(1) (genotypically rj(1)rj(1)) seedlings in plastic growth pouches. nodules first appeared on clark seedlings inoculated with bradyrhizobium japonicum usda 94 after 6 days. the mean number of nodules per plant was 13.9 +/- 0.8 after 24 days. in contrast, clark-rj(1) seedlings first nodulated at 12 days, and the mean number of nodules per p ...198716665600
regulation of nodulation in the soybean-rhizobium symbiosis : strain and cultivar variability.double inoculation (15 h apart) of the soybean cultivar williams with bradyrhizobium japonicum i-110ars reveals a rapid regulatory plant response that inhibits nodulation of distal portions of the primary root (m pierce, wd bauer 1984 plant physiol 73: 286-290). only living, homologous rhizobia elicit the response. we conducted similar double inoculation experiments to test the hypothesis that this is a universal phenomenon in soybean symbioses. we investigated interactions of the cultivar mccal ...198716665616
glycine-glomus-rhizobium symbiosis: v. effects of mycorrhiza on nodule activity and transpiration in soybeans under drought stress.soybean (glycine max [l.] merr.) plants were nodulated (bradyrhizobium japonicum) and either inoculated with the vesicular-arbuscular mycorrhizal (vam) fungus glomus mosseae (nicol. & gerd.) gerd. and trappe or left uncolonized. all plants were grown unstressed for 21 days initially. after this period, some vam and non-vam plants were exposed to four 8-day drought cycles while others were kept well watered. drought cycles were terminated by rewatering when soil moisture potentials reached -1.2 m ...198716665641
carbohydrate, organic acid, and amino acid composition of bacteroids and cytosol from soybean nodules.metabolites in bradyrhizobium japonicum bacteroids and in glycine max (l.) merr. cytosol from root nodules were analyzed using an isolation technique which makes it possible to estimate and correct for changes in concentration which may occur during bacteroid isolation. bacteroid and cytosol extracts were fractionated on ion-exchange columns and were analyzed for carbohydrate composition using gas-liquid chromatography and for organic acid and amino acid composition using high performance liquid ...198716665774
effect of nitrate on the organic acid and amino acid composition of legume nodules.nitrate supplied to legume plants inhibits the activity of nitrogenase in rhizobium bacteroids in root nodules. the accumulation of amino n which is known to occur in glycine max (l.) merr. nodules as nitrogenase activity declines was studied in more detail by analysis of changes in free amino acid composition in response to high nitrate supply. a 6-fold increase in asparagine concentration in bradyrhizobium japonicum bacteroids was found about the time of maximum nitrogenase inhibition. however ...198716665775
sequence of nifl from klebsiella pneumoniae: mode of action and relationship to two families of regulatory proteins.we present the nucleotide sequence of k. pneumoniae nifl, which negatively regulates nif transcription in response to oxygen and fixed nitrogen. it shows partial sequence homology to the general nitrogen regulatory proteins ntrb of k. pneumoniae and bradyrhizobium parasponiae. this homology is weaker than that shown between the nifa and ntrc activator components of the nif and general nitrogen control systems. the n-terminal section of the nifl protein includes a structural duplication sharing s ...19872838726
rhizobium symbiotic genes required for nodulation of legume and nonlegume hosts.parasponia, a woody member of the elm family, is the only nonlegume genus whose members are known to form an effective nitrogen-fixing symbiosis with bradyrhizobium or rhizobium species. the bradyrhizobium strain rp501, isolated from parasponia nodules, also nodulates the legumes siratro (macroptilium atropurpureum) and cowpea (vigna unguiculata). to test whether some of the same genes are involved in the early stages of legume and nonlegume nodulation, we generated transposon tn5 insertions in ...198716593814
isolation of a cytochrome aa(3) gene from bradyrhizobium japonicum.bradyhizobium japonicum strain lo501 is a tn5-induced mutant that does not express the terminal oxidase cytochrome aa(3) (cytochrome-c oxidase, ec 1.9.3.1). two and one-half kilobase pairs of lo501 genomic dna that flanks the transposon was isolated and used as a hybridization probe to obtain the wild-type gene from a cosmid library. two subcloned fragments from two of the isolated cosmids were ligated into broad host range vectors, and restriction maps of these fragments were generated. the res ...198716593835
k regulates bacteroid-associated functions of bradyrhizobium.cowpea bradyrhizobium 32h1 cells, when grown under 0.2% o(2), synthesize nitrogenase, as well as a methylammonium (ammonium) transport system and an electrogenic k(+)/h(+) antiporter. this effect was seen in growth medium containing 8-12 mm k(+) but not with 50 mum k(+). addition of k(+) to cells growing under low o(2) tensions in low-k(+) medium led to various phenotypic properties associated with bacteroids, including the ability to reduce acetylene, induction of an ammonium transport carrier ...198716593858
induction of bradyrhizobium japonicum common nod genes by isoflavones isolated from glycine max.the early events in legume nodulation by rhizobium spp. involve a conserved gene cluster known as the common nod region. a broad-host-range plasmid (pea2-21) containing a bradyrhizobium japonicum noddabc-lacz translational fusion was constructed and used to monitor nod gene expression in response to soybean root extract. two inducing compounds were isolated and identified. analysis using ultraviolet absorption spectra, proton nuclear magnetic resonance, and mass spectrometry showed that the two ...198716593884
direct response of bradyrhizobium japonicum nifa-mediated nif gene regulation to cellular oxygen status.the nifa genes of klebsiella pneumoniae and bradyrhizobium japonicum were constitutively expressed from the pbr329-derived chloramphenicol resistance promoter. the inserts of these nifa plasmid constructs were devoid of any other intact flanking genes. the nifa genes thus expressed led to a marked activation of a b. japonicum nifd-lacz fusion under microaerobic conditions. under aerobic growth conditions, however, activation was mediated only by the k. pneumoniae nifa gene but not by the b. japo ...198717193716
isolation of genes involved in nodulation competitiveness from rhizobium leguminosarum bv. trifolii t24.rhizobium leguminosarum bv. trifolii t24 produces a potent anti-rhizobial compound, trifolitoxin, and exclusively nodulates clover roots when in mixed inoculum with trifolitoxin-sensitive strains of r. leguminosarum bv. trifolii [schwinghamer, e. a. & belkengren r. p. (1968) arch. mikrobiol. 64, 130-145]. in the present study, the isolation of trifolitoxin production and resistance genes is described. a cosmid genomic library of t24 was prepared in plafr3. no trifolitoxin expression was observed ...198816593933
uniformity of the microsymbiont population from soybean nodules with respect to buoyant density.the microsymbiont population in soybean root nodules (glycine max l. cv williams 82 inoculated with bradyrhizobium japonicum 2143) was characterized during symbiotic development to determine the extent of heterogeneity in this population. the microsymbiont population was isolated by centrifugation through a continuous sucrose gradient (44 to 57% weight to weight ratio) and appeared homogeneous at each age examined up to 26 days after planting based on the symmetrical distribution of the populati ...198816665972
efficiency of nodule initiation in cowpea and soybean.when serial dilutions of a suspension of bradyrhizobium japonicum strain 138 were inoculated onto both soybean and cowpea roots, the formation of nodules in the initially susceptible region of the roots of both hosts was found to be linearly dependent on the log of the inoculum dosage until an optimum dosage was reached. approximately 30- to 100-fold higher dosages were required to elicit half-maximal nodulation on cowpea than on soybean in the initially susceptible zone of the root. however, at ...198816666056
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