Publications

regulation of o(2) concentration in soybean nodules observed by in situ spectroscopic measurement of leghemoglobin oxygenation.	a fiber optic spectrophotometric system was used to monitor the in vivo oxygenation of leghemoglobin in intact, attached soybean root nodules (glycine max l. merr. x usda 16 bradyrhizobium japonicum) which were flattened during development by growth in narrow, glass-walled cuvettes. when equilibrated at an external po(2) of 20 kilopascals, leghemoglobin was 36.6 +/- 5.4% oxygenated, a value estimated to represent an infected cell o(2) concentration of 21.5 nanomolar. increasing the external po(2 ...	1988	16666136
when does the self-regulatory response elicited in soybean root after inoculation occur?	the inoculation of soybean (glycine max l.) roots with bradyrhizobium japonicum produces a regulatory response that inhibits nodulation in the younger regions of the roots. by exposing the soybean roots to live homologous bacteria for only a short period of time, the question of whether or not early interactions of rhizobia with root cells, prior to infection, elicit this regulatory response has been explored. b. japonicum cells mixed with infective bacteriophages were applied to the roots and t ...	1988	16666343
expression and functional analysis of the rhizobium meliloti nifa gene.	the translational initiation point for rhizobium meliloti nifa, the specific activator for nitrogen fixation (nif) genes, was determined. when expressed in an escherichia coli linked transcriptional-translational system the dna coding for the r.meliloti nifa gene produced four polypeptide bands of 71 000, 67 000, 62 000 and 59 000 daltons. there are three in-frame atg codons at the n-terminus of the gene; by replacing the poor ribosome binding sites of the native dna with a synthetic consensus r ...	1988	16453824
cloning and mapping of a novel nodulation region from bradyrhizobium japonicum by genetic complementation of a deletion mutant.	the phenotypes of a set of bradyrhizobium japonicum 110 mutants with large deletions in the region of symbiotic gene cluster i were tested. the majority of the mutants showed a delayed nodulation on soybean and, by mixed-infection experiments, were found to be strongly reduced in their competitiveness. phenotypic comparison of mutants with different deletion endpoints allowed a preliminary localization of two genomic regions, called nod-1 and nod-2, which were required for normal nodulation on s ...	1988	16347539
nodulation, nitrogen fixation, and hydrogen oxidation by pigeon pea bradyrhizobium spp. in symbiotic association with pigeon pea, cowpea, and soybean.	the pigeon pea strains of bradyrhizobium cc-1, cc-8, uasgr(s), and f4 were evaluated for nodulation, effectiveness for n(2) fixation, and h(2) oxidation with homologous and nonhomologous host plants. strain cc-1 nodulated macroptilium atropurpureum, vigna unguiculata, glycine max, and g. soja but did not nodulate pisum sativum, phaseolus vulgaris, trigonella foenum-graecum, and trifolium repens. strain f4 nodulated g. max cv. peking and pi 434937 (malayan), but the symbioses formed were poor. si ...	1988	16347542
transposon tn5-generated bradyrhizobium japonicum mutants unable to grow chemoautotrophically with h(2).	twelve tn5-induced mutants of bradyrhizobium japonicum unable to grow chemoautotrophically with co(2) and h(2) (aut) were isolated. five aut mutants lacked hydrogen uptake activity (hup). the other seven aut mutants possessed wild-type levels of hydrogen uptake activity (hup), both in free-living culture and symbiotically. three of the hup mutants lacked hydrogenase activity both in free-living culture and as nodule bacteroids. the other two mutants were hup only in free-living culture. the latt ...	1988	16347549
dna probe method for the detection of specific microorganisms in the soil bacterial community.	we developed a protocol which yields purified bacterial dna from the soil bacterial community. the bacteria were first dispersed and separated from soil particles in the presence of polyvinylpolypyrrolidone, which removes humic acid contaminants by adsorption to this insoluble polymer. the soil bacteria were then collected by centrifugation and lysed by using a comprehensive protocol designed to maximize disruption of the various types of bacteria present. total bacterial dna was purified from t ...	1988	16347582
influence of glycine spp. on competitiveness of bradyrhizobium japonicum and rhizobium fredii.	the displacement of indigenous bradyrhizobium japonicum in soybean nodules with more effective strains offers the possibility of enhanced n(2) fixation in soybean (glycine max (l.) merr.). our objective was to determine whether the wild soybean (g. soja sieb. & zucc.) genotype pi 468397 would cause reduced competitiveness of important indigenous b. japonicum strains usda 31, 76, and 123 and thereby permit nodulation by rhizobium fredii, the fast-growing microsymbiont of soybean. in an initial ex ...	1988	16347589
colony dimorphism in bradyrhizobium strains.	ten isolates of bradyrhizobium spp. which form two colony types were studied; the isolates originated from a range of legume species. the two colony types differed in the amount of gum formed or size or both, depending on the strain. whole 7-day-old colonies of each type were subcultured to determine the proportion of cells which had changed to the other type. an iterative computerized procedure was used to determine the rate of switching per generation between the two types and to predict propo ...	1988	16347599
ecological indicators of native rhizobia in tropical soils.	the relationship between environment and abundance of rhizobia was described by determining the populations of root nodule bacteria at 14 diverse sites on the island of maui. mean annual rainfall at the sites ranged from 320 to 1,875 mm, elevation from 37 to 1,650 m, and soil ph from 4.6 to 7.9. four different soil orders were represented in this study: inceptisols, mollisols, ultisols, and an oxisol. the rhizobial populations were determined by plant infection counts of five legumes (trifolium ...	1988	16347624
synthesis of exopolysaccharide by bradyrhizobium japonicum during growth on hydroaromatic substrates.	the hydroaromatic acids shikimate and quinate, which may be available as carbon sources in the soil, supported production of only low levels of acidic exopolysaccharide by bradyrhizobium japonicum. exopolysaccharide production (micrograms per 10 cells) was 4.9 on quinate and 4.5 on shikimate; in comparison, it was 128 on adipate, 18 on l-arabinose, and 39 on d-glucose.	1988	16347670
melanin production by rhizobium strains.	different rhizobium and bradyrhizobium strains were screened for their ability to produce melanin. pigment producers (mel) were found among strains of r. leguminosarum biovars viceae, trifolii, and phaseoli, r. meliloti, and r. fredii; none of 19 bradyrhizobium strains examined gave a positive response. melanin production and nod genes were plasmid borne in r. leguminosarum biovar trifolii rs24. in r. leguminosarum biovar phaseoli cfn42 and r. meliloti gr015, mel genes were located in the respec ...	1988	16347690
numerical taxonomic analysis of some strains of rhizobium spp. that uses a qualitative coding of immunodiffusion reactions.	antigenic relationships among seven strains of bradyrhizobium japonicum were examined by immunodiffusion reactions, in which cells of each strain were reacted against each of the seven corresponding antisera. similar analyses were performed with rhizobium trifolii (28 strains), rhizobium meliloti (9 strains), and rhizobia of the cowpea miscellany (13 strains). antigens and antisera were reacted within each species only; serological interspecies cross-reactions were not performed. the results, sc ...	1988	16347692
nodulation and nitrogen fixation efficacy of rhizobium fredii with phaseolus vulgaris genotypes.	phaseolus plant introduction (pi) genotypes (consisting of 684 p. vulgaris, 26 p. acutifolius, 39 p. lunatus, and 5 p. coccineus accessions) were evaluated for their ability to form effective symbioses with strains of six slow-growing (bradyrhizobium) and four fast-growing (rhizobium fredii) soybean rhizobia. of the 684 p. vulgaris genotypes examined, three pis were found to form effective nitrogen-fixing symbioses with the r. fredii strains. while none of the bradyrhizobium strains nodulated an ...	1988	16347705
early infection and competition for nodulation of soybean by bradyrhizobium japonicum 123 and 138.	interactions of soybean with bradyrhizobium japonicum 123 (serogroup 123) and 138 (serogroup c1) were used to examine the relationship between early infection rates, competition for nodulation, and patterns of nodule occupancy. both strains formed more infections in autoclaved soil (sterile soil) than in untreated soil (unsterile soil). inoculation did not increase numbers of infection threads in unsterile soil-grown plants, where infection of proximal portions of primary roots was complete by 5 ...	1988	16347710
host ranges of the incn group plasmid pcu1 and its minireplicon in gram-negative purple bacteria.	the bacterial host ranges of the conjugatively self-transmissible incn group plasmid pcu1 and its mobilizable miniderivative, pcu785, were examined. species of the gram-negative purple bacteria were chosen for this study. conjugative mobilization of pcu785 into a wide variety of bacteria was facilitated by the presence of orit of the broad-host-range plasmid rk2 in pcu785. although the host range of the incn tra system of pcu1 is broad, the host range of its replicon is limited. however, the pcu ...	1988	16347740
effects of bradyrhizobium japonicum and soybean (glycine max (l.) merr.) phosphorus nutrition on nodulation and dinitrogen fixation.	cells of bradyrhizobium japonicum were grown in media containing either 1.0 mm or 0.5 mum phosphorus. in growth pouch experiments, infection of the primary root of soybean (glycine max (l.) merr.) by b. japonicum usda 31, 110, and 142 was significantly delayed when p-limited cells were applied to the root. in a greenhouse experiment, b. japonicum usda 31, 110, 122, and 142 grown with sufficient and limiting p were used to inoculate soybeans which were grown with either 5 mum or 1 mm p nutrient s ...	1988	16347750
stability of bradyrhizobium japonicum inoculants after introduction into soil.	bradyrhizobium japonicum usda 125-sp, usda 138, and usda 138-sm had been used as inoculants for soybean (glycine max (l.) merr.) in soils previously free of b. japonicum. at 8 to 13 years after their release, these strains were reisolated from soil samples. a total of 115 isolates were obtained through nodules, and seven colonies were obtained directly by a serological method. the stability of the inoculants was confirmed by comparing the reisolated cultures with their respective parental strain ...	1988	16347768
two host-inducible genes of rhizobium fredii and characterization of the inducing compound.	random transcription fusions with mu d1(kan lac) generated three mutants in rhizobium fredii (strain usda 201) which showed induction of beta-galactosidase when grown in root exudate of the host plants glycine max, phaseolus vulgaris, and vigna ungliculata. two genes were isolated from a library of total plasmid dna of one of the mutants, 3f1. these genes, present in tandem on a 4.2-kilobase hindiii fragment, appear in one copy each on the symbiotic plasmid and do not hybridize to the rhizobium ...	1988	2447061
conformational changes in the membrane-bound hydrogenase of bradyrhizobium japonicum. evidence that the redox state of the enzyme affects its accessibility to protease and membrane-impermeant reagents.	the sensitivity of the membrane-bound hydrogenase of bradyrhizobium japonicum to inactivation by proteases and membrane-impermeant protein modification reagents was compared under hydrogen versus oxygen. in membrane vesicles, the half-life of enzyme inactivation by trypsin of the h2-reduced enzyme was approximately 10 min, whereas o2-oxidized enzyme was much less sensitive to trypsin inactivation (half-life of over 90 min). diazobenzene sulfonate (dabs) affected the enzyme activity in a manner s ...	1988	3053719
nucleotide sequence of the genetic loci encoding subunits of bradyrhizobium japonicum uptake hydrogenase.	an indispensable part of the hydrogen-recycling system in bradyrhizobium japonicum is the uptake hydrogenase, which is composed of 34.5- and 65.9-kda subunits. the gene encoding the large subunit is located on a 5.9-kilobase fragment of the h2-uptake-complementing cosmid phu52 [zuber, m., harker, a.r., sultana, m.a. & evans, h.j. (1986) proc. natl. acad. sci. usa 83, 7668-7672]. we have now determined that the structural genes for both subunits are present on this fragment. two open reading fram ...	1988	3054886
selenium increases hydrogenase expression in autotrophically cultured bradyrhizobium japonicum and is a constituent of the purified enzyme.	we have investigated the effect of added selenite on autotrophic growth and the time course of hydrogen oxidation derepression in bradyrhizobium japonicum 122des cultured in a medium purified to remove selenium compounds. in addition, hydrogenase was purified to near homogeneity and examined for the specific incorporation of se into the enzyme. the addition of se at 0.1 microm significantly increased total cell protein and hydrogenase specific activity of harvested cells. also, the addition of s ...	1988	3056905
cloning and sequencing of the genes encoding the large and the small subunits of the h2 uptake hydrogenase (hup) of rhodobacter capsulatus.	the structural genes (hup) of the h2 uptake hydrogenase of rhodobacter capsulatus were isolated from a cosmid gene library of r. capsulatus dna by hybridization of bradyrhizobium japonicum. the r. capsulatus genes were localized on a 3.5 kb hindiii fragment. the fragment, cloned onto plasmid pac76, restored hydrogenase activity and autotrophic growth of the r. capsulatus mutant jp91, deficient in hydrogenase activity (hup-). the nucleotide sequence, determined by the dideoxy chain termination me ...	1988	3067084
nickel as a micronutrient element for plants.	the detrimental effects of excessive ni on plant growth have been well known for many years. more recent evidence indicates that ni is required in small amounts for normal plant growth and development. ni is an essential component of urease in plants and microorganisms. a deficiency of ni in plants is reported to result in necrotic lesions in leaves in response to toxic accumulations of urea. urease plays an essential role in mobilization of nitrogenous compounds in plants, a process that is esp ...	1988	3076427
regulation of the fixa gene and fixbc operon in bradyrhizobium japonicum.	the transcriptional start site of the bradyrhizobium japonicum fixbc operon was identified by nuclease s1 mapping. it was located approximately 700 base pairs upstream of fixb and was preceded by a promoter sequence that showed strong homology to the b. japonicum fixa promoter and thus to the general nif consensus promoter sequence. further transcript mapping experiments revealed that fixa and fixbc transcription in b. japonicum strictly depended on the presence of the regulatory gene nifa and o ...	1988	3343218
lack of carbon substrate repression of uptake hydrogenase activity in bradyrhizobium japonicum sr.	the expression of ex planta uptake hydrogenase (hup) activity in bradyrhizobium japonicum sr induced in the absence or presence of carbon substrates was compared. hup activity was influenced by ph, indicating that acidification of induction medium with low buffering capacity resulting from carbon substrate metabolism inhibited hup activity. cell suspensions in medium with adequate buffering capacity and carbon substrate were limited in o2; increasing o2 availability to cells during induction sti ...	1988	3350794
identification of a new bradyrhizobium japonicum gene (frxa) encoding a ferredoxinlike protein.	an open reading frame of 74 codons was identified downstream of the nifb gene of bradyrhizobium japonicum 110. the predicted amino acid sequence shared 63% similarity with the rhodopseudomonas palustris ferredoxin i sequence. we propose to name the gene frxa. the frxa gene was found to be cotranscribed with the nifb gene. an insertion mutation within frxa hardly affected nitrogen fixation activity.	1988	3350797
essential and non-essential domains in the bradyrhizobium japonicum nifa protein: identification of indispensable cysteine residues potentially involved in redox reactivity and/or metal binding.	the amino acid sequence of the bradyrhizobium japonicum nitrogen fixation regulatory protein nifa, as derived from the nucleotide sequence of the nifa gene, was aligned to the corresponding protein sequences from klebsiella pneumoniae, rhizobium meliloti and rhizobium leguminosarum biovar viciae. high conservation was found in the central domain and in the cooh-terminal, putative dna binding domain, whereas very little homology was present within the first 250 amino acids from the nh2-terminus. ...	1988	3357773
quantitative assay for binding of bradyrhizobium japonicum to cultured soybean cells.	incubation of bradyrhizobium japonicum with the cultured soybean cell line sb-1 resulted in the adhesion of the bacteria to the plant cells. an antiserum was raised against b. japonicum, and the 125i-labeled immunoglobulin fraction was used to quantitate the number of bacteria bound to the soybean cells. the measurement of 125i-labeled antibody binding correlated well with parallel assays by microscopic observation. using this quantitation, we have optimized the parameters of the assay in terms ...	1988	3410819
dicarboxylic acid transport in bradyrhizobium japonicum: use of rhizobium meliloti dct gene(s) to enhance nitrogen fixation.	a recombinant plasmid encoding rhizobium meliloti sequences involved in dicarboxylic acid transport (plasmid prk290:4:46) (e. bolton, b. higgisson, a. harrington, and f. o'gara, arch. microbiol. 144:142-146, 1986) was used to study the relationship between dicarboxylic acid transport and nitrogen fixation in bradyrhizobium japonicum. the expression of the dct sequences on plasmid prk290:4:46 in b. japonicum cj1 resulted in increased growth rates in media containing dicarboxylic acids as the sole ...	1988	3422072
role of the bradyrhizobium japonicum ntrc gene product in differential regulation of the glutamine synthetase ii gene (glnii).	we isolated the ntrc gene from bradyrhizobium japonicum, the endosymbiont of soybean (glycine max), and examined its role in regulating nitrogen assimilation. two independent ntrc mutants were constructed by gene replacement techniques. one mutant was unable to produce ntrc protein, while the other constitutively produced a stable, truncated ntrc protein. both ntrc mutants were unable to utilize potassium nitrate as a sole nitrogen source. in contrast to wild-type b. japonicum, the ntrc null mut ...	1988	2903856
identification of the klebsiella pneumoniae glnb gene: nucleotide sequence of wild-type and mutant alleles.	the glnb gene of klebsiella pneumoniae, which encodes the nitrogen regulation protein pii, has been cloned and sequenced. the gene encodes a 12429 dalton polypeptide and is highly homologous to the escherichia coli glnb gene. the sequences of a glnb mutation which causes glutamine auxotrophy and of a tn5 induced gln+ suppressor of this mutation were also determined. the glutamine auxotrophy was deduced to be the result of a modification of the uridylylation site of pii, and the suppression was s ...	1988	2907369
characterization of the rhizobium leguminosarum genes nodlmn involved in efficient host-specific nodulation.	three nodulation genes, nodl, nodm and nodn, were isolated from rhizobium leguminosarum and their dna sequences were determined. the three genes are in the same orientation as the previously described nodfe genes and the predicted molecular weights of their products are 20,105 (nodl), 65,795 (nodm) and 18,031 (nodn). analysis of gene regulation using operon fusions showed that nodl, nodm and nodn are induced in response to flavanone molecules and that this induction is nodd-dependent. in additio ...	1988	3132583
regulation of nod gene expression in bradyrhizobium japonicum.	the best inducers of nod::lacz translational fusions in bradyrhizobium japonicum are isoflavones, primarily genistein and daidzein. upstream of the nodabc genes in b. japonicum is a novel gene, nody, which is coregulated with nodabc. measurements of the activity of lacz fusions to the nodd gene of b. japonicum show that this gene is inducible by soybean seed extract and selected flavonoid chemicals. the induction of the nody abc and nodd operons appears to require a functional nodd gene, indicat ...	1988	3146016
molybdate transport by bradyrhizobium japonicum bacteroids.	bacteroid suspensions of bradyrhizobium japonicum usda 136 isolated from soybeans grown in mo-deficient conditions were able to transport molybdate at a nearly constant rate for up to 1 min. the apparent km for molybdate was 0.1 microm, and the vmax was about 5 pmol/min per mg (dry weight) of bacteroid. supplementation of bacteroid suspensions with oxidizable carbon sources did not markedly increase molybdate uptake rates. anaerobically isolated bacteroids accumulated twice as much mo in 1 h as ...	1988	3192511
protoporphyrinogen oxidation, a step in heme synthesis in soybean root nodules and free-living rhizobia.	extracts of the crude bacteroid fraction of symbiotically grown bradyrhizobium japonicum were much more active in oxidizing protoporphyrinogen to protoporphyrin than were extracts of cells grown under free-living conditions, especially when assayed in atmospheres containing only traces of oxygen. this correlates with the higher heme content of the microaerophilic nodules. furthermore, the high level of oxidative activity in the crude bacteroid fraction was associated with an uncharacterized memb ...	1989	2914857
immunological relationship among hydrogenases.	we examined the immunological cross-reactions of 11 different hydrogenase antigens with 9 different hydrogenase antibodies. included were antibodies and antigens of both subunits of the hydrogenases of bradyrhizobium japonicum and thiocapsa roseopersicina. the results showed a strong relationship among the ni-fe dimeric hydrogenases. the two subunits of ni-fe dimeric hydrogenases appeared immunologically distinct: specific interactions occurred only when antibodies to the 60- and 30-kilodalton s ...	1989	2464579
o-antigen from bradyrhizobium japonicum lipopolysaccharide inhibits intercellular (symplast) communication between soybean (glycine max) cells.	the technique of fluorescence redistribution after photobleaching was utilized to measure intercellular movement of low molecular weight fluorescent hydrophilic substances across the cell wall/membrane interface between contiguous soybean (glycine max (l.) merr. cv. mandarin) root cells (sb-1 cell line) in tissue culture. lipopolysaccharide (lps) purified from bradyrhizobium japonicum r110d, a gram-negative bacterium that normally infects and induces nodulation in soybean roots in vivo, inhibits ...	1989	2473070
expression of bradyrhizobium japonicum nodulation gene in rhizobium fredii nod mutants.	the b. japonicum usda 110 plafr1 gene library was transferred to tn5-induced rhizobium fredii usda 191-4 nod- mutants with helper plasmid prk2013. smr tcr transconjugants occurred with a frequency of 5 x 10(-4). the transconjugants were purified and used to inoculate germinated soybean seeds. seven nodules were obtained in the nodulation experiment. the fast-growing nod+ smr tcr rhizobium fredii strain was isolated from all nodules. each isolate had acquired a new plasmid with a molecular mass o ...	1989	2491321
characterization of hydrogen-uptake activity in the hyperthermophile pyrodictium brockii.	pyrodictium brockii is a hyperthermophilic archaebacterium with an optimal growth temperature of 105 degrees c. p. brockii is also a chemolithotroph, requiring h2 and co2 for growth. we have characterized p. brockii hydrogen-uptake activity with regard to temperature, ability to couple hydrogen oxidation to artificial electron acceptor reduction, sensitivity to o2, and cellular localization. the hydrogen-uptake activity was localized predominantly in a particulate fraction, was reversibly inhibi ...	1989	2492097
protein phosphorylation in bradyrhizobium japonicum bacteroids and cultures.	protein phosphorylation was demonstrated in bradyrhizobium japonicum bacteroids in vivo and in cultures in vivo and in vitro. comparison of in vivo-labeled phosphoproteins of bacteroids and of cultured cells showed differences in both the pattern and intensity of labeling. in cultured cells, comparison of the labeling patterns and intensities of in vivo- and in vitro-labeled phosphoproteins showed a number of similarities; however, several phosphoproteins were found only after one of the two lab ...	1989	2498290
the bradyrhizobium japonicum fixbcx operon: identification of fixx and of a 5' mrna region affecting the level of the fixbcx transcript.	the bradyrhizobium japonicum fixx gene was identified and shown to be essential for symbiotic and free-living, microaerobic nitrogen fixation. the fixx gene encodes a ferredoxin-like protein which may be involved in a redox process (electron transport?) essential for nitrogenase activity. this gene was localized downstream of fixc and its expression was dependent on the fixb promoter, providing evidence for the existence of a fixbcx operon. mutagenesis and sequence analysis of the unusually long ...	1989	2503674
fine-tuning of nif and fix gene expression by upstream activator sequences in bradyrhizobium japonicum.	the significance of bradyrhizobium japonicum upstream activator sequences (uass) for differential nifa-mediated fix and nif gene expression was investigated by two means: (i) hybrid fixa- and fixb-lacz fusions were constructed by transposing a nifh-uas cartridge in front of their promoters; and (ii) b. japonicum mutants were generated carrying specific chromosomal deletions or uas cartridge insertions within the fixa, fixb or nifh promoter-upstream regions. expression of fixa was not affected, a ...	1989	2503675
production of extracellular nucleic acids by genetically altered bacteria in aquatic-environment microcosms.	the factors which affect the production of extracellular dna by genetically altered strains of escherichia coli, pseudomonas aeruginosa, pseudomonas cepacia, and bradyrhizobium japonicum in aquatic environments were investigated. cellular nucleic acids were labeled in vivo by incubation with [3h]thymidine or [3h]adenine, and production of extracellular dna in marine waters, artificial seawater, or minimal salts media was determined by detecting radiolabeled macromolecules in incubation filtrates ...	1989	2506807
identification, cloning, and sequence analysis of the nitrogen regulation gene ntrc of agrobacterium tumefaciens c58.	we describe the cloning of an ntrc gene of agrobacterium tumefaciens c58 by interspecific complementation of an escherichia coli ntrc mutant. restriction mapping and southern blot analysis of the complementing clone identified a 1.7-kb ecori-pvuii dna fragment whose sequence was determined. analysis of this sequence revealed coding regions corresponding to a complete ntrc gene and the c-terminal region of an ntrb gene. amino acid sequence comparisons of a. tumefaciens ntrc protein with ntrc sequ ...	1989	2520824
nodule-specific kinases phosphorylating nuclear factors in isolated nuclei.	in vitro phosphorylation of total nuclear proteins from soybean (glycine max l) nodules formed by bradyrhizobium japonicum 61a76 showed several differences in comparison with those from uninfected roots or embryonic-axes nuclei. three types of protein phosphorylations were observed in nodule nuclei: ca(2+)- and calmodulin-independent, ca(2+)- and calmodulin-dependent, and ca(2+)-dependent but calmodulin-independent. in addition, ca(2+)-dependent dephosphorylation of some nuclear proteins was obs ...	1989	2535508
identification and isolation of genes essential for h2 oxidation in rhodobacter capsulatus.	mutants of rhodobacter capsulatus unable to grow photoautotrophically with h2 and co2 were isolated. those lacking uptake hydrogenase activity as measured by h2-dependent methylene blue reduction were analyzed genetically and used in complementation studies for the isolation of the wild-type genes. results of further subcloning and transposon tn5 mutagenesis suggest the involvement of a minimum of five genes. hybridization to the 2.2-kilobase-pair ssti fragment that lies within the coding region ...	1989	2536678
an unusual gene cluster for the cytochrome bc1 complex in bradyrhizobium japonicum and its requirement for effective root nodule symbiosis.	two adjacent genes in bradyrhizobium japonicum, fbcf and fbch, encode the rieske iron sulfur protein and cytochromes b and c1, characteristic constituents of the respiratory complex iii. remarkably, fbch is a single gene of which the 5' half codes for cytochrome b and the 3' half codes for cytochrome c1. experimental evidence suggests that a large fbch precursor is posttranslationally processed into the two proteins. b. japonicum fbcf and fbch insertion mutants grow aerobically but are unable to ...	1989	2541921
identification of bradyrhizobium nod genes involved in host-specific nodulation.	three loci important for soybean nodulation by bradyrhizobium japonicum were delimited by tn5 mutagenesis on a 5.3-kilobase ecori fragment adjacent to the nodabc genes. results of hybridization studies suggested that this region is conserved in bradyrhizobium species but absent in all rhizobium species. lacz translational fusions of two of the loci contained in this region were found to be inducible by host-produced flavonoid chemicals via a mechanism requiring a functional nodd gene product. a ...	1989	2542223
hydrogenase synthesis in bradyrhizobium japonicum hupc mutants is altered in sensitivity to dna gyrase inhibitors.	in the hupc mutants of bradyrhizobium japonicum sr, regulation of expression of hydrogenase is altered; the mutants synthesize hydrogenase constitutively in the presence of atmospheric levels of oxygen. the dna gyrase inhibitors nalidixic acid, novobiocin, and coumermycin were used to inhibit growth of wild-type and mutant cells. for each inhibitor tested, growth of mutant and wild-type strains was equally sensitive. however, in contrast to the wild type, the hupc mutants synthesized hydrogenase ...	1989	2547335
adenylate cyclase and cyclic amp phosphodiesterase in bradyrhizobium japonicum bacteroids.	adenylate cyclase and cyclic amp (camp) phosphodiesterase have been identified and partially characterized in bacteroids of bradyrhizobium japonicum 3i1b-143. adenylate cyclase activity was found in the bacteroid membrane fraction, whereas camp phosphodiesterase activity was located in both the membrane and the cytosol. in contrast to other microorganisms, b. japonicum adenylate cyclase remained firmly bound to the membrane during treatment with detergents. adenylate cyclase was activated four- ...	1989	2548992
the nifa gene product from rhizobium leguminosarum biovar trifolii lacks the n-terminal domain found in other nifa proteins.	the nifa gene has been identified between the fixx and nifb genes in the clover microsymbiont rhizobium leguminosarum biovar trifolii (r.i. bv. trifolii) strain anu843. expression of the nifa gene is induced in the symbiotic state and site-directed mutagenesis experiments indicate that nifa expression is essential for symbiotic nitrogen fixation. interestingly, the predicted r.i. bv. trifolii nifa protein lacks an n-terminal domain that is present in the homologous proteins from r.i. bv. viciae, ...	1989	2552256
expression of the adenyl cyclase-encoding gene (cya) of rhizobium meliloti f34: existence of two cya genes?	to gain insight into the role of cyclic amp (camp) in gram-negative soil bacteria, we have studied the expression of an adenyl cyclase-encoding gene 'cya' of rhizobium meliloti f34. in both escherichia coli and bradyrhizobium japonicum, the gene is expressed from a promoter(s) contained on a 2.6-kb fragment of the cloned insert, which may indicate the presence of a functional 'cya' promoter or the coincidental presence of sequences which can function as promoters in these two species. the study ...	1989	2555267
identification of a regulatory nifa type gene and physical mapping of cloned new nif regions of azospirillum brasilense.	three new tn5-mutagenized nif genes of azospirillum brasilense were characterized. the sizes of the restriction fragments and the restriction maps of the cloned nif dna regions showed that these nif genes are distinct from those reported earlier, e.g. nifhdk, nife, nifus, fixabc. the nif27 mutant was identified as a nifa type regulatory gene of a. brasilense (a) by genetic complementation with nifa of klebsiella pneumoniae, (b) by the absence of nitrogenase iron protein in western protein blots ...	1989	2559312
rhizobium meliloti 1021 has three differentially regulated loci involved in glutamine biosynthesis, none of which is essential for symbiotic nitrogen fixation.	we have cloned and characterized three distinct rhizobium meliloti loci involved in glutamine biosynthesis (glna, glnii, and glnt). the glna locus shares dna homology with the glna gene of klebsiella pneumoniae, encodes a 55,000-dalton monomer subunit of the heat-stable glutamine synthetase (gs) protein (gsi), and complemented an escherichia coli glna mutation. the glnii locus shares dna homology with the glnii gene of bradyrhizobium japonicum and encodes a 36,000-dalton monomer subunit of the h ...	1989	2563998
isolation, characterization, and complementation of rhizobium meliloti 104a14 mutants that lack glutamine synthetase ii activity.	the glutamine synthetase (gs)-glutamate synthase pathway is the primary route used by members of the family rhizobiaceae to assimilate ammonia. two forms of glutamine synthetase, gsi and gsii, are found in rhizobium and bradyrhizobium species. these are encoded by the glna and glnii genes, respectively. starting with a rhizobium meliloti glna mutant as the parent strain, we isolated mutants unable to grow on minimal medium with ammonia as the sole nitrogen source. for two auxotrophs that lacked ...	1989	2570058
glutamine synthetase ii in rhizobium: reexamination of the proposed horizontal transfer of dna from eukaryotes to prokaryotes.	we have determined the dna sequence of a rhizobium meliloti gene that encodes glutamine synthetase ii (gsii). the deduced amino acid sequence was compared to that of bradyrhizobium japonicum gsii and those of various plant and mammalian glutamine synthetases (gs) in order to evaluate a proposal that the gene for this enzyme was recently transferred from plants to their symbiotic bacteria. there is 83.6% identity between the r. meliloti and b. japonicum proteins. the bacterial gsii proteins avera ...	1989	2575672
fast-growing root nodule bacteria produce a novel polyamine, aminobutylhomospermidine.	polyamines in various root nodule bacteria including bradyrhizobium japonicum, rhizobium fredii, r. leguminosarum, r. meliloti and r. loti were identified by capillary gas chromatography. homospermidine was the polyamine present in highest concentration in all the rhizobia tested. in addition to putrescine and homospermidine, fast-growing type of rhizobial cells contained a novel polyamine, aminobutylhomospermidine, nh2(ch2)4nh(ch2)4nh(ch2)4nh2. the unusual tetraamine was not found in the cells ...	1989	2597153
common nodabc genes in nod locus 1 of azorhizobium caulinodans: nucleotide sequence and plant-inducible expression.	azorhizobium caulinodans strain ors571 induces nitrogen-fixing nodules on roots and stem-located root primordia of sesbania rostrata. two essential nod loci have been previously identified in the bacterial genome, one of which (nod locus 1) shows weak homology with the common nodc gene of rhizobium meliloti. here we present the nucleotide sequence of this region and show that it contains three contiguous open reading frames (orfa, orfb and orfc) that are related to the nodabc genes of rhizobium ...	1989	2615763
immunological identification and distribution of dissimilatory heme cd1 and nonheme copper nitrite reductases in denitrifying bacteria.	polyclonal antibodies were used to identify heme or copper nitrite reductases in the following groups: 23 taxonomically diverse denitrifiers from culture collections, 100 numerically dominant denitrifiers from geographically diverse environments, and 51 denitrifiers from a culture collection not selected for denitrification. antisera were raised against heme nitrite reductases from pseudomonas aeruginosa and pseudomonas stutzeri and against copper nitrite reductase from achromobacter cycloclaste ...	1989	2624465
molecular cloning of a gene for indole-3-acetamide hydrolase from bradyrhizobium japonicum.	a plafr1 cosmid genomic library of wild-type bradyrhizobium japonicum j1063 was constructed. a cosmid clone designated pbjj4, containing a 26-kilobase (kb) dna insert, was identified as being able to confer the ability to convert alpha-naphthaleneacetamide acid on b. japonicum j1b7 rifr, which cannot perform this conversion. the gene coding for the enzyme that converts alpha-naphthaleneacetamide to alpha-naphthaleneacetic acid was localized in the 3.5-kb region of pbjj4 by recloning in plasmid p ...	1989	2646294
estimation of nitrogenase activity in the presence of ethylene biosynthesis by use of deuterated acetylene as a substrate.	nitrogenase reduces deuterated acetylene primarily to cis dideuterated ethylene. this can be distinguished from undeuterated ethylene by the use of fourier transform infrared spectroscopy. characteristic bands in the region from 800 to 3,500 cm-1 can be used to identify and quantitate levels of these products. this technique is applicable to field studies of nitrogen fixation where ethylene biosynthesis by plants or bacteria is occurring. we have verified the reaction stoichiometry by using kleb ...	1989	2655535
construction of chimaeric promoter regions by exchange of the upstream regulatory sequences from fdhf and nif genes.	hybrid 5' regulatory regions were constructed in which the upstream activator sequence (uas) and promoter of various nif genes were exchanged with the upstream regulatory sequence (urs) of the fdhf gene from escherichia coli. they were analysed for their regulatory response under different growth conditions with the aid of fdhf'-'lacz or nif'-'lacz fusions. placement of the uas from the bradyrhizobium japonicum nifh gene in front of the spacer (dna region between urs and promoter) plus promoter ...	1989	2664422
the azorhizobium caulinodans nitrogen-fixation regulatory gene, nifa, is controlled by the cellular nitrogen and oxygen status.	the nucleotide sequence of the azorhizobium caulinodans ors571 nifa locus was determined and the deduced nifa amino acid sequence compared with that of nifa from other nitrogen-fixing species. highly conserved domains, including helix-turn-helix and atp-binding motifs, and specific conserved residues, such as a cluster of cysteines, were identified. the nifa 5' upstream region was found to contain dna sequence motifs highly homologous to promoter elements involved in nifa/ntr-mediated control an ...	1989	2664425
identification of dna regions homologous to nitrogen fixation genes nife, nifus and fixabc in azospirillum brasilense sp7.	a 30 kb dna region from azospirillum brasilense sp7, containing the nitrogenase structural genes (nifhdk), has been cloned. the presence of nif genes, in the 20 kb located next to nifhdk, was explored by tn5 mutagenesis after subcloning various restriction fragments in the broad-host-range suicide vehicle psup202. over 25 mutations due to tn5 random insertions were obtained in the 20 kb and each recombined into the genome of strain sp7. four new nif loci were identified, located at about 4, 9, 1 ...	1989	2695597
mutational analysis of the bradyrhizobium japonicum common nod genes and further nod box-linked genomic dna regions.	by insertional and deletional marker replacement mutagenesis the common nod region of bradyrhizobium japonicum was examined for the presence of additional, essential nodulation genes. an open reading frame located in the 800 bp large intergenic region between nodd1 and noda did not appear to be essential for nodulation of soybean. furthermore, a strain with a deletion of the nodi- and nodj-like genes downstream of nodc had a nod+ phenotype. a mutant with a 1.7 kb deletion immediately downstream ...	1989	2710106
lipid a with 2,3-diamino-2,3-dideoxy-glucose in lipopolysaccharides from slow-growing members of rhizobiaceae and from "pseudomonas carboxydovorans".	lipid a's from two bradyrhizobium species and from the phylogenetically closely related species "pseudomonas carboxydovorans" were found to contain 2,3-diamino-2,3-dideoxy-glucose as lipid a backbone sugar. in contrast, three representatives of the genus rhizobium, as well as the phylogenetically related species agrobacterium tumefaciens, contain solely glucosamine as lipid a backbone sugar. these findings support independent studies on the phylogenetical relatedness based on 16s rrna-data of th ...	1989	2719525
purification and partial characterization of the rhizobium leguminosarum biovar viciae ca2+-dependent adhesin, which mediates the first step in attachment of cells of the family rhizobiaceae to plant root hair tips.	the ca2+-dependent adhesin which mediates the first step in attachment of bacteria of the family rhizobiaceae to plant root hair tips was isolated from the surface of rhizobium leguminosarum biovar viciae cells; its ability to inhibit attachment of r. leguminosarum to pea root hair tips was used as a bioassay. isolated adhesin was found to be able to inhibit attachment of both carbon-limited and manganese-limited r. leguminosarum cells. a multicolumn purification procedure was developed which re ...	1989	2738027
structural and functional analysis of nitrogenase genes from the broad-host-range rhizobium strain anu240.	the genes encoding the structural components of nitrogenase, nifh, nifd and nifk, from the fast-growing, broad-host-range rhizobium strain anu240 have been identified and characterized. they are duplicated and linked in an operon nifhdk in both copies. sequence analysis of the nifh gene from each copy, together with partial sequence analysis of the nifd and nifk genes, and restriction endonuclease analysis suggested that the duplication is precise. comparison of the fe-protein sequence from stra ...	1989	2744485
dual control of the bradyrhizobium japonicum symbiotic nitrogen fixation regulatory operon fixr nifa: analysis of cis- and trans-acting elements.	aerobic expression of the fixr nifa operon in bradyrhizobium japonicum was shown to depend on a cis-acting, promoter-upstream dna sequence located between the -24/-12 promoter and position -86 relative to the transcription start site. an adenine at position -66 was essential for maximal expression. a chromosomal deletion of the upstream activator sequence (uas) led to a symbiotically defective phenotype which was typical of nifa mutants. b. japonicum crude extracts contained a protein that bound ...	1989	2753853
cytoplasmic membrane systems involved in bacterium release into soybean nodule cells as studied with two bradyrhizobium japonicum mutant strains.	two bradyrhizobium japonicum, tn5-induced, mutant strains, ml126 and ml150, were studied. both induce host cell division to form normal-sized nodules that do not fix nitrogen and whose cells have very few bacteroids (bar-). early-infection (15 days post infection) cells have much endoplasmic reticulum (er), numerous golgi bodies, and large vacuoles that are probably secondary lysosomes. later the cytoplasm of the host cells of both are dominated by hundreds of vesicles containing only finely fib ...	1989	2759102
nucleotide sequence of a gene for indole-3-acetamide hydrolase from bradyrhizobium japonicum.		1989	2771653
critical spacing between two essential cysteine residues in the interdomain linker of the bradyrhizobium japonicum nifa protein.	a special sequence motif in the bradyrhizobium japonicum nifa protein, consisting of two functionally essential cysteines separated by four other amino acids (cys-aa4-cys), has been proposed to be part of a potential metal-binding site [(1988) nucleic acids res. 16, 2207-2224]. using the techniques of oligonucleotide-directed mutagenesis, we report here that several of the four intervening amino acids can be replaced by others without loss of nifa function. the deletion of one amino acid to give ...	1989	2792368
bradyrhizobium japonicum glnb, a putative nitrogen-regulatory gene, is regulated by ntrc at tandem promoters.	the glnb gene from bradyrhizobium japonicum, the endosymbiont of soybeans (glycine max), was isolated and sequenced, and its expression was examined under various culture conditions and in soybean nodules. the b. japonicum glnb gene encodes a 12,237-dalton polypeptide that is highly homologous to the glnb gene products from klebsiella pneumoniae and escherichia coli. the gene is located directly upstream from glna (encoding glutamine synthetase), a linkage not observed in enteric bacteria. the g ...	1989	2793830
acetate-activating enzymes of bradyrhizobium japonicum bacteroids.	acetyl coenzyme a (acetyl-coa) synthetase and acetate kinase were localized within the soluble portion of bradyrhizobium japonicum bacteroids, and no appreciable activity was found elsewhere in the nodule. the presence of each acetate-activating enzyme was confirmed by separation of the two enzyme activities on a hydroxylapatite column, by substrate dependence of each enzyme in both the forward and reverse directions, by substrate specificity, by inhibition patterns, and also by identification o ...	1989	16347818
bradyrhizobium japonicum survival in and soybean inoculation with fluid gels.	the utilization of gels, which are used for fluid drilling of seeds, as carriers of bradyrhizobium japonicum for soybean (glycine max (l.) merr.) inoculation was studied. gels of various chemical composition (magnesium silicate, potassium acrylate-acrylamide, grafted starch, and hydroxyethyl cellulose) were used, although the hydroxyethyl cellulose gels were more extensively investigated. gel inocula were prepared by mixing gel powder with liquid cultures of b. japonicum (2% [wt/vol]). the popul ...	1989	16347870
physiological characterization of dicarboxylate-induced pleomorphic forms of bradyrhizobium japonicum.	when bradyrhizobium japonicum i-110 was transferred into medium containing 40 mm succinate or 40 mm fumarate, over 90% of the bacteria acquired a swollen, pleomorphic form similar to that of bacteroids. the induction of pleomorphism was dependent on the carbon substrate and concentration but was independent of the hydrogen ion and sodium ion concentration. cell extracts of rod-shaped and pleomorphic cells contained enzymes required for sugar catabolism and gluconeogenesis. variations in these en ...	1989	16347873
use of the chrome azurol s agar plate technique to differentiate strains and field isolates of rhizobium leguminosarum biovar trifolii.	identification of rhizobium and bradyrhizobium strains and especially of indigenous isolates continues to be one of the major difficulties associated with competition studies. because there is no universally accepted method, the method of choice depends on preference, experience, and equipment. here, an agar plate technique was used to distinguish strains and field isolates of rhizobium leguminosarum biovar trifolii to provide a basis for identifying nodule occupants in further competition studi ...	1989	16347877
improvement of rhizobium inoculants.	a practical approach was used to develop a rhizobium (bradyrhizobium) japonicum inoculant that increases soybean (glycine max (l.) merr.) yield in fields with indigenous rhizobium populations, which typically outcompete strains present in existing commercial inoculants and therefore decrease the value of inoculant use. field tests managed by several universities in the mississippi delta region averaged a 169-kg/ha (p < 0.01) grain yield increase. the inoculant contains a mixture of mutants selec ...	1989	16347891
competition by bradyrhizobium strains for nodulation of the nonlegume parasponia andersonii.	bradyrhizobium strains isolated from the nonlegume parasponia spp. formed a group of strains that were highly competitive for nodulation of p. andersonii when paired with strains isolated from legumes. strains from legumes, including those of similar effectiveness to ngr231 and cp283, were not able to form nodules as single occupants on p. andersonii in the presence of parasponia strains. however, ngr86, an isolate from macroptilium lathyroides, jointly occupied one-third of the nodules formed w ...	1989	16347913
role of dna superhelicity in regulation of bacteroid-associated functions of bradyrhizobium sp. strain 32h1.	bradyrhizobium sp. strain 32h1 cells express a number of bacteroid-associated functions and repress some functions related to the free-living state when grown ex planta under conditions of low (0.2%) oxygen tension and relatively high levels (>8 mm) of medium k. expression of the bacteroid-associated phenotype was blocked by the dna gyrase inhibitor novobiocin. because the degree of negative supercoiling of dna is the result of the activities of both dna gyrase and topoisomerase i, we measured t ...	1989	16347935
influence of bradyrhizobium japonicum location and movement on nodulation and nitrogen fixation in soybeans.	the influence of seed and soil inoculation on bradyrhizobial migration, nodulation, and n(2) fixation was examined by using two bradyrhizobium japonicum strains of contrasting effectiveness in n(2) fixation. seed-inoculated strains formed fewer nodules on soybeans (mostly restricted to the tap and crown roots within 0 to 5 cm from the stem base) than did bradyrhizobia distributed throughout the soil or inoculated at specific depths. nodulation was greater below the depths at which bradyrhizobial ...	1989	16347964
nodulating competitiveness of a nonmotile tn7 mutant of bradyrhizobium japonicum in nonsterile soil.	a nonmotile mutant of bradyrhizobium japonicum serogroup 127 was generated by tn7 mutagenesis and matched with the wild type against a common competitor in studies of soybean nodulation in nonsterile soil. the tn7 mutant was very similar to the wild type in growth rate in culture, soybean lectin-binding ability, flagellar morphology, and nodulating capability, but it had a longer lag phase. competing strains were distributed uniformly in soil in various ratios and at different population densiti ...	1989	16347986
nodulation of glycine max by six bradyrhizobium japonicum strains with different competitive abilities.	the root nodule locations of six bradyrhizobium japonicum strains were examined to determine if there were any differences which might explain their varying competitiveness for nodule occupancy on glycine max. when five strains were added to soybeans in plastic growth pouches in equal proportions with a reference strain (u.s. department of agriculture, strain 110), north carolina strain 1028 and strain 110 were the most competitive for nodule occupancy, followed by u.s. department of agriculture ...	1989	16347987
localization of bacteria and hemoglobin in root nodules of parasponia andersonii containing both bradyrhizobium strains and rhizobium leguminosarum biovar trifolii.	dual occupancy of parasponia andersonii nodules with different bradyrhizobium strains and rhizobium leguminosarum biovar trifolii was frequently obtained when two strains were inoculated into plants grown aseptically in tubes. since reisolates of bradyrhizobium strains from dually occupied nodules acquired the ability to nodulate trifolium repens, the spatial relationship of the two species of bacteria during nodule initiation and development was investigated and their proximity was demonstrated ...	1989	16347995
bradyrhizobium japonicum inoculant mobility, nodule occupancy, and acetylene reduction in the soybean root system.	in the american midwest, superior inoculant rhizobia applied to soybeans usually occupy only 5 to 20% of nodules, and response to inoculation is the exception rather than the rule. attempts to overcome this problem have met with limited success. we evaluated the ability of bradyrhizobium japonicum, supplied as a seed coat inoculant, to stay abreast of the infectible region of the developing soybean root system. the rhizoplane population of the inoculant strain declined with distance from site of ...	1989	16348026
host plant effects on nodulation and competitiveness of the bradyrhizobium japonicum serotype strains constituting serocluster 123.	strains in bradyrhizobium japonicum serocluster 123 are the major indigenous competitors for nodulation in a large portion of the soybean production area of the united states. serocluster 123 is defined by the serotype strains usda 123, usda 127, and usda 129. the objective of the work reported here was to evaluate the ability of two soybean genotypes, pi 377578 and pi 417566, to restrict the nodulation and reduce the competitiveness of serotype strains usda 123, usda 127, and usda 129 in favor ...	1989	16348029
unaltered nodulation competitiveness of a strain of bradyrhizobium sp. (lotus) after a decade in soil.	a bradyrhizobium sp. (lotus) strain that formed a soil population that was highly competitive for nodulation of lotus pedunculatus 11 years after its introduction into a field soil and a culture of the same strain stored lyophilized were compared with an antibiotic-resistant mutant in respect of their nodulation competitiveness. the mutant was less competitive than the wild-type strain it was isolated from and had to be present at a cell ratio of 5.76:1 in mixed inoculum in sand culture to form ...	1989	16348061
identification of a locus upstream from the hydrogenase structural genes that is involved in hydrogenase expression in bradyrhizobium japonicum.	a locus involved in the expression of the uptake hydrogenase system of bradyrhizobium japonicum was identified adjacent to genes encoding the hydrogenase subunits. a cloned fragment of dna was used to complement to autotrophy a hup putative regulatory mutant of b. japonicum. the mutant strain lacked hydrogenase activity and synthesized low levels of the large subunit of hydrogenase as determined by western gels. tn5-induced mutagenesis located the region within the fragment which was necessary f ...	1989	16348066
selection and initial characterization of partially nitrate tolerant nodulation mutants of soybean.	since no(3) (-) availability in the rooting medium seriously limits symbiotic n(2) fixation by soybean (glycine max [l.] merr.), studies were initiated to select nodulation mutants which were more tolerant to no(3) (-) and were adapted to the midwest area of the united states. three independent mutants were selected in the m(2) generation from ethyl methanesulfonate or n-nitroso-n-methylurea mutagenized williams seed. all three mutants (designated nod1-3, nod2-4, and nod3-7) were more extensivel ...	1989	16666510
occurrence of h(2)-uptake hydrogenases in bradyrhizobium sp. (lupinus) and their expression in nodules of lupinus spp. and ornithopus compressus.	fifty-four strains of bradyrhizobium sp. (lupinus) from worldwide collections were screened by a colony hybridization method for the presence of dna sequences homologous to the structural genes of the bradyrhizobium japonicum hydrogenase. twelve strains exhibited strong colony hybridization signals, and subsequent southern blot hybridization experiments showed that they fell into two different groups on the basis of the pattern of ecori fragments containing the homology to the hup probe. all str ...	1989	16666550
in vivop nmr spectroscopic studies of soybean bradyrhizobium symbiosis: i. optimization of parameters.	(31)p nmr spectroscopy was used to study in vivo the symbiotic state established between soybean (glycine max [l.] merr. cv williams) and bradyrhizobium japonicum (usda 110 and 138). different experimental conditions were used to maintain perfused, respiring detached or attached nodules in an nmr magnet. the ph of the perfusion medium affected the cytoplasmic ph and the resolution of the spectra. the internal pi content and distribution were assessed as a function of nodule age and green-house g ...	1989	16666690
cytokinin production by bradyrhizobium japonicum.	although there is considerable circumstantial evidence for the involvement of cytokinins in legume nodulation, the cytokinins produced by rhizobia have not been well characterized. bradyrhizobium japonicum 61a68, a bacterium which nodulates soybean (glycine max [l.] merr.), was grown in defined medium. cytokinins were purified from the culture medium by amberlite xad-2 chromatography and fractionated by column chromatography on sephadex lh-20 in 35% ethanol. pooled fractions from the sephadex co ...	1989	16666691
leghemoglobin in lupin plants (lupinus albus cv multolupa).	leghemoglobin was localized by immunogold techniques in nodules of lupinus albus cv multolupa inoculated with bradyrhizobium sp. (lupinus) strain islu 16. the protein localization was performed in nodules embedded in spurr's and araldite epoxy resins and lowycryl k4m. a very good preservation of both the ultrastructure and antigenicity was obtained with the tissues embedded in araldite following glutaraldehyde fixation and unpostfixed in osmium tetroxide. lupin leghemoglobin is a stable and abun ...	1989	16666792
cytochrome mutants of bradyrhizobium induced by transposon tn5.	transposon tn5 was used to mutate bradyrhizobium japonicum usda 61n. from over 5000 clones containing tn5, 12 were selected and purified using a chemical reaction to identify oxidase-deficient clones. four classes of mutants were identified based on the alterations in cytochromes. most of the mutants had alterations in more than one cytochrome. southern hybridization analysis of restricted genomic dna of a representative strain of each class demonstrated that each mutant had a single tn5 insert. ...	1989	16666807
isoenzymes of superoxide dismutase in nodules of phaseolus vulgaris l., pisum sativum l., and vigna unguiculata (l.) walp.	the activity and isozymic composition of superoxide dismutase (sod; ec 1.15.1.1) were determined in nodules of phaseolus vulgaris l., pisum sativum l., and vigna unguiculata (l.) walp. formed by rhizobium phaseoll 3622, r. ieguminosarum 3855, and bradyrhizobium sp. br7301, respectively. a mn-sod was present in rhizobium and two in bradyrhizobium and bacteroids. nodule mitochondria from all three legume species had a single mn-sod with similar relative mobility, whereas the cytosol contained seve ...	1989	16666924
lack of systemic suppression of nodulation in split root systems of supernodulating soybean (glycine max [l.] merr.) mutants.	wild-type soybean (glycine max [l] merr. cv bragg) and a nitrate-tolerant supernodulating mutant (nts382) were grown in split root systems to investigate the involvement of the autoregulation response and the effect of timing of inoculation on nodule suppression. in bragg, nodulation of the root portion receiving the delayed inoculation was suppressed nearly 100% by a 7-day prior inoculation of the other root portion with bradyrhizobium japonicum strain usda 110. significant suppression was also ...	1989	16666934
hydrogen inhibition of nitrogen reduction by nitrogenase in isolated soybean nodule bacteroids.	dihydrogen, a by-product of biological nitrogen fixation, is a competitive inhibitor of n(2) reduction by nitrogenase. to evaluate the significance of h(2) inhibition in vivo, we have measured the apparent inhibition constant for h(2) inhibition of n(2) reduction in bradyrhizobium japonicum bacteroids isolated from soybean nodules. the rate of n(2) reduction was measured as ammonia production by bacteroids incubated in a buffer containing 200 micromolar leghemoglobin and 10 millimolar succinate ...	1989	16667084
developmental regulation of enzymes of sucrose and hexose metabolism in effective and ineffective soybean nodules.	soybean (glycine max) nodules formed by inoculation with either an effective strain or an ineffective (noninvasive, nodule-forming) strain of bradyrhizobium japonicum were assayed for changes in developmental patterns of carbon metabolic enzymes of the plant nodule cells. of the enzyme activities measured, only sucrose synthase, glutamine synthetase, and alcohol dehydrogenase were altered in the ineffective nodules relative to the effective nodules. sucrose synthase and glutamine synthetase acti ...	1990	16667280
ureide assay for measuring nitrogen fixation by nodulated soybean calibrated by n methods.	we report experiments to quantify the relationships between the relative abundance of ureide-n in root-bleeding sap, vacuum-extracted sap, and hot water extracts of stems and petioles of nodulated soybean (glycine max [l.] merrill cv bragg) and the proportion of plant n derived from nitrogen fixation. additional experiments examined the effects of plant genotype and strain of rhizobia on these relationships. in each of the five experiments reported, plants of cv bragg (experiment 1), cv lincoln ...	1990	16667494