Publications

rhizobium japonicum serogroup and hydrogenase phenotype distribution in 12 states.	a survey was conducted in 1980 on 972 isolates of rhizobium japonicum obtained from 65 soybean field locations in 12 states. isolates were examined for the hydrogenase (hup) phenotype and somatic serogroup identity. only 20% of the isolates were hup, with a majority of hup isolates occurring in 10 of the 12 states. the most predominant serogroup was 31 (21.5%), followed by 123 (13.6%). although most serogroups contained a majority of hup isolates, marked differences occurred. none of the isolate ...	1984	16346502
complementary methods for the differentiation of rhizobium meliloti isolates.	because of the scarcity of literature on the successful use of serological methods for differentiation of rhizobium meliloti isolates, the objectives of this study were to provide a rationale for selecting isolates to which antisera could be raised and to appraise the suitability of published methods of preparing r. meliloti antigens for the serological identification of field isolates. we used one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis to develop protein profiles ...	1984	16346506
effect of plasmid pij1008 from rhizobium leguminosarum on symbiotic function of rhizobium meliloti.	plasmid pij1008, which carries determinants for uptake hydrogenase (hup) activity, was transferred from rhizobium leguminosarum to rhizobium meliloti without impairing the capacity of the latter species to form root nodules on alfalfa. the plasmid was still present in rhizobia reisolated from the root nodules of 12 different alfalfa cultivars, but only low levels of hup activity were detected in alfalfa.	1984	16346527
interaction of rhizobium sp. with toxin-producing fungus in culture medium and in a tropical soil.	experiments were conducted to determine the influence of a toxin-producing fungus on a rhizobial population in yeast-mannitol medium and in a tropical soil. the fungus, which was isolated from a highly weathered soil (tropeptic eutrustox), was identified as a metarhizum sp. the density of rhizobial populations established in yeast-mannitol medium in the absence of the fungus was 10 times higher than that established in its presence. however, the fungus did not exert similar antagonistic influenc ...	1984	16346537
fine structure of succinate-swollen rhizobium trifolii 0403.	transmission electron micrographs of glutaraldehyde- oso(4)-fixed rhizobium trifolii 0403 before and after cells were treated with 16.6 mm succinate showed that treated cells increased in mass by increasing cytoplasmic volume. the morphology of succinate-treated cells was identical to that of bacteroids, and the appearances of the envelope and periplasmic space were similar. the primary difference was in inclusion number and type.	1984	16346547
invalidity of the concept of slow growth and alkali production in cowpea rhizobia.	a total of 103 rhizobial strains representing the cowpea miscellany and rhizobium japonicum were studied with regard to growth rate, glucose metabolic pathways, and ph change in culture medium. doubling times ranged from 1.4 +/- 0.04 to 44.1 +/- 5.2 h; although two populations of "fast-growing" and "slow-growing" rhizobia were noted, they overlapped and were not distinctly separated. twenty-four strains which had doubling times of less than 8 h all showed nadp-linked 6-phosphogluconate dehydroge ...	1984	16346589
fast-growing rhizobium japonicum that effectively nodulates several commercial glycine max l. merrill cultivars.	several isolates of fast-growing rhizobium japonicum that nodulate the wild soybean glycine soja have been recently described (keyser et al., science 215:1631-1632, 1982). we demonstrate that one of these isolates, designated prc 440 or usda 191, has a wider host range than that previously reported and is able to nodulate several commercial glycine max cultivars as effectively as does slow-growing r. japonicum 61a76. electron microscopic examination revealed no obvious differences between strain ...	1984	16346594
competition among rhizobium spp. for nodulation of leucaena leucocephala in two tropical soils.	the successful nodulation of legumes by a rhizobium strain is determined by the competitive ability of that strain against the mixture of other native and inoculant rhizobia. competition among six leucaena rhizobial strains in single and multistrain inoculants were studied. field inoculation trials were conducted in an oxisol and a mollisol soil, both of which contained indigenous leucaena-nodulating rhizobia. strain-specific fluorescent antibodies were used for the identification of the strains ...	1984	16346600
nitrogen fixation and carbon dioxide assimilation in rhizobium japonicum.	in free-living rhizobium japonicum cultures, the stimulatory effect of co(2) on nitrogenase (acetylene reduction) activity was mediated through ribulose bisphosphate carboxylase activity. two mutant strains (cj5 and cj6) of r. japonicum defective in co(2) fixation were isolated by mitomycin c treatment. no ribulose bisphosphate carboxylase activity could be detected in strain cj6, but a low level of enzyme activity was present in strain cj5. mutant strain cj5 also exhibited pleiotropic effects o ...	1984	16346608
enhancing soybean rhizosphere colonization by rhizobium japonicum.	a study was conducted to seek means to increase the colonization of the rhizosphere of soybeans (glycine max l. merrill) by rhizobium japonicum. for this purpose, a strain of r. japonicum that was resistant to benomyl, streptomycin, and erythromycin was used. the numbers of r. japonicum rose quickly in the first 2 days after soybean seeds were planted in soil and then rapidly fell. the decline was slower if the seeds were coated with benomyl. this fungicide reduced the numbers of bacteria and pr ...	1984	16346616
root hair deformation, bacterial attachment, and plant growth in wheat-azospirillum associations.	seven azospirillum strains induced more deformation of root hairs of wheat than did strains of rhizobium leguminosarum, azotobacter chroococcum, or escherichia coli. azospirillum sp. strain sp245 caused the most deformation. strain sp245 (isolated from surface sterile roots of wheat) and strain sp7 (isolated from the rhizosphere of a forage grass) were compared with regard to their effects on root hair deformation, their attachment to roots, and their effects on the growth of four wheat cultivar ...	1984	16346680
variation in preference for rhizobium meliloti within and between medicago sativa cultivars grown in soil.	variation in nodulation preferences for rhizobium strains within and between medicago sativa cultivars was assessed in the greenhouse with plants grown in leonard jars and two soils of diverse origin (lanark and ottawa), using inocula consisting of effective individual or paired strains of r. meliloti which could be recognized by high-concentration antibiotic resistance. the results indicated considerable variability in host preferences for r. meliloti among plants within cultivars but not betwe ...	1984	16346682
underexpression of ap from r-plasmids in fast-growing rhizobium species.	the presence of the plasmid rp1 in the cells of rhizobium leguminosarum strains rld1, 300, and 248, r. phaseoli 1233, r. trifolii strains t1 and 6661, and r. meliloti 4013 was found to appreciably increase bacterial resistance toward kanamycin and tetracycline but not toward ampicillin. the presence of 16 other r-plasmids in r. leguminosarum was also found to either not increase or only marginally increase bacterial resistance toward ampicillin. it appears now that underexpression of the plasmid ...	1984	16346686
effect of salinity on nodule formation by soybean.	a split-root growth system was employed to evaluate the effect of nacl on nodule formation by soybean (glycine max l. merr. cv davis). by applying the salinity stress and rhizobial inoculum to only one-half the root system, the effects of salinity on shoot growth were eliminated in the nodulation process. rhizobium colonization of inoculated root surfaces was not affected by the salt treatments (0.0, 26.6, 53.2, and 79.9 millimolar nacl). while shoot dry weight remained unaffected by the treatme ...	1984	16663389
host recognition in the rhizobium-soybean symbiosis: detection of a protein factor in soybean root exudate which is involved in the nodulation process.	the mechanism of host-symbiont recognition in the soybean-rhizobium symbiosis was investigated utilizing mutants of r. japonicum defective in nodulation. soybeans were grown in clear plastic growth pouches allowing the identification of the area on the root most susceptible to rhizobium nodulation; the area between the root tip (rt) and smallest emergent root hair (serh). the location of nodules in relation to this developing zone is an indication of the rate of nodule initiation. nodules were s ...	1984	16663392
phytohormones, rhizobium mutants, and nodulation in legumes : v. cytokinin metabolism in effective and ineffective pea root nodules.	[(3)h]zeatin riboside was supplied to intact pea (pisum sativum) plants either onto the leaves or onto the root nodules. when applied directly to nodules, approximately 70% of recovered radioactivity remained in the nodules, approximately 15% was detected in the root system, and 15% was in the shoot. however, when supplied to the leaves, little (3)h was transported, with approximately 0.05% of recovered radioactivity being found in the root system and nodules. on a fresh weight basis, nodules ac ...	1984	16663404
role of lectins in the specific recognition of rhizobium by lotononis bainesii.	fluorescein isothiocyanate (fitc)-labeled lectin purified from the root of lotononis bainesii baker was bound by cells of five out of seven l. bainesii-nodulating strains of rhizobium under culture conditions. with the exception of a strain of rhizobium leguminosarum, strains of noninfective rhizobia failed to bind the root lectin under these conditions. the two nonlectin binding l. bainesii-specific strains did not bind root lectin on the l. bainesii rhizoplane although this was observed with t ...	1984	16663509
suppression of nodule development of one side of a split-root system of soybeans caused by prior inoculation of the other side.	in a split-root system of soybeans (glycine max l. merr), inoculation of one half-side suppressed subsequent development of nodules on the opposite side. at zero time, the first side of the split-root system of soybeans received rhizobium japonicum strain usda 138 as the primary inoculum. at selected time intervals, the second side was inoculated with the secondary inoculum, a mixture of r. japonicum strain usda 138 and strain usda 110. in a short-day season, nodulation by the secondary inoculum ...	1984	16663555
experimental determination of the respiration associated with soybean/rhizobium nitrogenase function, nodule maintenance, and total nodule nitrogen fixation.	the total metabolic cost of soybean (glycine max l. mer clark) nodule nitrogen fixation was empirically separated into respiration associated with electron flow through nitrogenase and respiration associated with maintenance of nodule function.rates of co(2) evolution and h(2) evolution from intact, nodulated root systems under ar:o(2) atmospheres decreased in parallel when plants were maintained in an extended dark period. while h(2) evolution approached zero after 36 hours of darkness at 22 de ...	1984	16663599
rhizobium infection and nodule development in soybean are affected by exposure of the cotyledons to light.	the initiation of rhizobium infections and the development of nodules on the primary root of soybean glycine max l. merr cv williams seedlings are strongly affected by exposure of the cotyledons/hypocotyls to light. seedlings in plastic growth pouches were inoculated with r. japonicum in dim light and the position of the root tip of each seedling was marked on the face of the pouch. the pouches were covered and kept in the dark for various times before exposing the upper portions of the plants ( ...	1984	16663609
a highly sensitive, flow through h(2) gas analyzer for use in nitrogen fixation studies.	studies of h(2) evolution by n(2) fixing systems are frequently limited by an inability to accurately measure h(2) gas concentrations of less than about 10 microliters per liter. in this study, a h(2) gas analyzer is described which is able to accurately and reproducibly detect up to 100 times lower h(2) concentrations than most thermal conductivity gas chromatographs or other conventional instruments used for the measurement of h(2) gas. this high level of sensitivity (maximum of about 0.02 mic ...	1984	16663669
a transmissible plant shoot factor promotes uptake hydrogenase activity in rhizobium symbionts.	shoot/root grafting studies showed organ and host cultivar effects on net h(2) evolution from pisum sativum l. root nodules. net h(2) evolution from those nodules represents the sum of h(2) formed by rhizobium nitrogenase and h(2) oxidized by any uptake hydrogenase present in the bacteria. grafts between pea cultivars ;ji1205' or ;alaska' and ;feltham first' in symbioses with r. leguminosarum 128c53 showed that shoots of both ji1205 and alaska increased h(2) uptake significantly (p </= 0.05) in ...	1984	16663677
purine synthesis and catabolism in soybean seedlings : the biogenesis of ureides.	the ureides, allantoin and allantoic acid, are the major nitrogenous substances transported within the xylem of n(2)-fixing soybeans (glycine max l. merr. cv amsoy 71). the ureides accumulated in the cotyledons, roots and shoots of soybean seedlings inoculated with rhizobium or grown in the presence of 10 millimolar nitrate. the patterns of activity for uricase and allantoinase, enzymes involved in ureide synthesis, were positively correlated with the accumulation of ureides in the roots and cot ...	1984	16663743
enzymes of the poly-beta-hydroxybutyrate and citric acid cycles of rhizobium japonicum bacteroids.	the activities of several enzymes of the citric acid and poly-beta-hydroxybutyrate cycles were measured in rhizobium japonicum 3i1b-143 bacteroids which had been isolated from soybean nodules by sucrose gradient centrifugation. during the period of developing nitrogenase activity, the specific activity of fumarase, hydroxybutyrate dehydrogenase, beta-ketothiolase, and pyruvate dehydrogenase complex increased whereas acetoacetate-succinyl-coa transferase and isocitrate dehydrogenase decreased. ma ...	1984	16663750
adsorption of slow- and fast-growing rhizobia to soybean and cowpea roots.	roots of soybean (glycine max [l.] merr. cv hardee) and cowpea (vigna unguiculata [l.] walp. cv pink eye purple hull) were immersed in suspensions containing 10(4)rhizobium cells per milliliter of a nitrogen-free solution. after 30 to 120 minutes the roots were rinsed, and the distal 2-centimeter segments excised and homogenized. portions of the homogenates then were plated on a yeast-extract mannitol medium for bacterial cell counts. the adsorption capacities of four slow-growing rhizobia and a ...	1984	16663761
effects of n(2) deficiency on transport and partitioning of c and n in a nodulated legume.	nodulated root systems of white lupin (lupinus albus l. cv ultra: rhizobium strain wu425) were exposed to ar:o(2) (80:20, v/v) or ar:n(2):o(2) (70:10:20, v/v/v) and c and n partitioning were examined over a 9- or 10-day period in comparison with control plants with nodulated roots retained in air. accumulation of n ceased in plants exposed to ar:o(2) or was much reduced in plants exposed to ar:n(2):o(2), but net c assimilation rates and profiles of c utilization remained similar to those of cont ...	1984	16663823
effects of short-term n(2) deficiency on n metabolism in legume nodules.	the study aimed to test the hypothesis that ammonia production by rhizobium bacteroids provides not only a source of nitrogen for growth but has a central regulatory role in maintaining the metabolic activity and functional integrity of the legume nodule. production of ammonia in intact, attached nodules was interrupted by short-term (up to 3 days) exposure of the nodulated root systems of cowpea (vigna unguiculata l. walp cv vita 3: rhizobium cb 756) and lupin (lupinus albus l. cv ultra: rhizob ...	1984	16663910
tissue cultures derived from ineffective root nodules of alfalfa : callus initiation and enzymic comparisons.	callus tissue cultures were developed from apical meristem regions of tumor-like ineffective root nodules of alfalfa. callus growth was a function of tissue source and hormone composition and concentration. callus derived from ineffective nodules also were shown not to contain rhizobium meliloti.glutamate dehydrogenase, glutamine synthetase, glutamate synthase, glutamate oxaloacetate transaminase and phosphoenolpyruvate carboxylase activities were present in callus cultures and in the respective ...	1984	16663985
mapping of the protein-coding regions of rhizobium meliloti common nodulation genes.	an 8.5-kb ecori fragment containing the common nod region of the megaplasmid prme41b of rhizobium meliloti was recloned in plasmids of escherichia coli, and a detailed restriction map was established. the region can express at least eight proteins in e. coli minicells and in an in vitro transcription/translation system, prepared from e. coli. protein coding regions were determined by subcloning of restriction fragments, deletion mutations and by transposon mutagenesis. the coding regions for at ...	1984	16453541
nodulation of soybeans as affected by half-root infection with heterodera glycines.	a split-root technique was applied to soybean, glycine max (l.) merr. cv. lee 68, to characterize the nature of the nodulation suppression by race 1 of the soybean cyst nematode (scn), heterodera glycines. root-halves of each split-root plant were inoculated with rhizobium japonicum, and one root-half only was inoculated with various numbers of scn eggs. nodulation (indicated by nodule number, nodule weights, and ratio of nodule weight to root weight) and nitrogen-fixing capacity (indicated by r ...	1984	19295882
mapping and expression of a regulatory nitrogen fixation gene (fixd) of rhizobium meliloti.	a 3.5-kb hindiii fragment from the main nif/fix (nitrogen fixation) gene cluster of rhizobium meliloti was characterized by studying its expression in escherichia coli minicells. a coding region for two polypeptides of 68 k and 66 k was mapped using tn5 insertions and hybrid fusion polypeptides. dna sequence analysis of this region revealed the presence of an open reading frame capable of coding for a polypeptide of 59.9 k mol. wt. this coding region was designated fixd. plasmids, constitutively ...	1985	16453640
specific targeting of membrane nodulins to the bacteroid-enclosing compartment in soybean nodules.	rhizobium bacteroids in nodule cells are surrounded by the peribacteroid membrane (pbm), which is derived from the host plasma membrane during infection. the pbm was purified from r. japonicum 61a76-induced soybean nodules and analyzed by comparing it with the host cell plasma membrane for the presence of nodulins, nodule-specific plant proteins. nodulins were found in pbm by reacting western blots with a nodule-specific antiserum raised against the pbm. peribacteroid fluid (the fluid enclosed i ...	1985	16453645
the nodd gene of rhizobium leguminosarum is autoregulatory and in the presence of plant exudate induces the noda,b,c genes.	to analyse nod gene expression in rhizobium leguminosarum, a broad host-range lacz protein fusion vector was constructed. two protein fusions, nodc-lacz and nodd-lacz, were used to measure the regulation of expression of the promoters of the noda,b,c and the nodd transcripts by measuring the induced levels of beta-galactosidase activity in r. leguminosarum. in the absence of plant root exudate the nodd-lacz hybrid was expressed but the nodc-lacz hybrid was not. the expression of the nodd-lacz hy ...	1985	16453650
nitrate inhibition of legume nodule growth and activity : i. long term studies with a continuous supply of nitrate.	the synthesis and accumulation of nitrite has been suggested as a causative factor in the inhibition of legume nodules supplied with nitrate. plants were grown in sand culture with a moderate level of nitrate (2.1 to 6.4 millimolar) supplied continuously from seed germination to 30 to 50 days after planting. in a comparison of nitrate treatments, a highly significant negative correlation between nitrite concentration in soybean (glycine max [l.] merr.) nodules and nodule fresh weight per shoot d ...	1985	16664051
nitrate inhibition of legume nodule growth and activity : ii. short term studies with high nitrate supply.	soybean plants (glycine max [l.] merr) were grown in sand culture with 2 millimolar nitrate for 37 days and then supplied with 15 millimolar nitrate for 7 days. control plants received 2 millimolar nitrate and 13 millimolar chloride and, after the 7-day treatment period, all plants were supplied with nil nitrate. the temporary treatment with high nitrate inhibited nitrogenase (acetylene reduction) activity by 80% whether or not rhizobium japonicum bacteroids had nitrate reductase (nr) activity. ...	1985	16664052
effect of temperature on h(2) evolution and acetylene reduction in pea nodules and in isolated bacteroids.	nitrogenase (ec 1.7.99.2) activity in pea (pisum savitum) nodules formed after infection with rhizobium leguminosarum (lacking uptake hydrogenase) was measured as acetylene reduction, h(2) evolution in air and h(2) evolution in ar:o(2). with detached roots the relative efficiency, calculated from acetylene reduction, showed a decrease (from 55 to below 0%) with increasing temperature. with excised nodules and isolated bacteroids similar results were obtained. however, the relative efficiency cal ...	1985	16664054
host recognition in the rhizobium-soybean symbiosis : evidence for the involvement of lectin in nodulation.	rhizobium japonicum mutant strain hs111 was previously shown to be defective in the rate of initiation of infection leading to subsequent nodule formation (1984 plant physiol 74: 84-89). mutant strain hs111's defect in nodulation can be phenotypically reversed to wild type levels by pretreatment with root exudates from all soybean varieties that have been tested. the data indicate that lectin-rhizobium interaction is necessary for the phenotypic reversal of the nodulation characteristics of muta ...	1985	16664109
nodule-specific polypeptides from effective alfalfa root nodules and from ineffective nodules lacking nitrogenase.	in addition to leghemoglobin, at least nine nodule-specific polypeptides from the alfalfa (medicago sativa l.)-rhizobium meliloti symbiosis were identified by immune assay. some of these polypeptides may be subunits of larger proteins but none appeared to be subunits of the same multimeric protein. all nine of the nodule-specific polypeptides were localized to within the plant cytosol; they were not found in extracts of bacteroids or in the peribacteroid space. at least one of these nodule-speci ...	1985	16664146
a supernodulation and nitrate-tolerant symbiotic (nts) soybean mutant.	the nodulation characteristics of soybean (glycine max) mutant nts382 are described. the mutant nodulated significantly more than the parent cultivar bragg in the presence and absence of several combined nitrogen sources (kno(3), urea, nh(4)cl, and nh(4)no(3)). the number of nodules on the tap root and on lateral roots was increased in the mutant line. in the presence of kno(3) and urea, nitrogenase activity was considerably higher in nts382 than in bragg. mutant plants were generally smaller th ...	1985	16664203
glycine-glomus-rhizobium symbiosis: ii. antagonistic effects between mycorrhizal colonization and nodulation.	soybean (glycine max [l.] merr.) plants grown in pot cultures were inoculated with the vesicular-arbuscular mycorrhizal (vam) fungus glomus mosseae (nicol. & gerd.) gerd. and trappe and rhizobium japonicum strain 61a118 at planting (g(1)r(1)) or at 20 days (g(20)r(20)), or with one of the endophytes after the other has colonized the host root (g(1)r(20), g(20)r(1)). nodulated (pr(1)) and vam (g(1)n) dipartite associations, or nonsymbiotic plants (pn) using nutrient solutions with n, p, or n + p ...	1985	16664528
effectiveness of rhizobium strains used in inoculants after their introduction into soil.	rhizobium strains used in inoculants for trifolium spp., medicago spp., glycine max, and lotus pedunculatus were isolated from nodules of these legumes grown in soils into which the rhizobia had been introduced 4 to 8 years before. isolations were made from a total of 420 nodules. nodule occupancy by the inoculant strains varied from 17.7% for a soybean strain to 100% in the case of l. pedunculatus whose specific rhizobia did not occur in the soils studied. in general, inoculant strains isolated ...	1985	16346692
root hair deformations associated with fractionated extracts from rhizobium trifolii.	components from culture fluid and whole cells of rhizobium trifolii were examined for effects on root hair morphology of white clover seedlings (trifolium repens var. ladino). cell-free culture fluid, exopolysaccharides, supernatant fluid from the precipitation of the exopolysaccharides, capsular polysaccharides, lipopolysaccharides, and a protein fraction from culture fluids were assayed for morphogenetic effects on the root hairs of axenically grown clover seedlings. crude fractions were chrom ...	1985	16346709
possible involvement of phage-like structures in antagonism of cowpea rhizobia by rhizobium trifolii.	a reduction in the viability of cowpea rhizobia was observed when rhizobium trifolii iari and cowpea rhizobium strain 3824 were inoculated together in soil. the reduction in number of cowpea rhizobia in soil was found to be associated with the reduction in number of nodules per plant and retardation in plant growth. an antimicrobial substance was isolated from r. trifolii which, on electron microscopic investigation, demonstrated the presence of several phage-like structures.	1985	16346736
inoculant maturity influences survival of rhizobia on seed.	survival of rhizobium trifolii on seeds of arrowleaf clover (trifolium versiculosum savi) and subclover (trifolium subterraneum l.) was affected by the maturity of peat-, vermiculite-, and charcoal-based inoculants. ten times more rhizobia survived on seed 4 days after inoculation when inoculants were stored (cured) before being utilized as compared with uncured inoculants. increasing the curing time of inoculants beyond 4 weeks had little effect on increasing survival of seed-applied rhizobia.	1985	16346738
general method for the identification of plasmid species in fast-growing soil microorganisms.	using a horizontal gel electrophoresis method, we demonstrated reproducibly the presence of indigenous plasmids in different rhizobium, agrobacterium, and pseudomonas strains. the method yields a large amount of plasmid dna and is sensitive in detecting megaplasmids with molecular weights higher than 5 x 10. in two rhizobium meliloti strains, a megaplasmid other than the low-mobility plasmid already known was detected.	1985	16346763
simplified enzyme-linked immunosorbent assay for routine identification of rhizobium japonicum antigens.	a simple, reliable, and flexible modification of the indirect enzyme-linked immunosorbent assay was developed for the identification of rhizobium japonicum antigens from cultures and nodules. the procedure emphasizes efficient use of time and reagents, adaptability to variously equipped laboratories, and maintenance of sensitivity levels that are adequate for ecological studies.	1985	16346765
studies on the inoculation and competitiveness of a rhizobium leguminosarum strain in soils containing indigenous rhizobia.	the competitiveness of a rhizobium leguminosarum strain was investigated at two separate locations in field inoculation studies on commercially grown peas. the soil at each location (sites i and ii) contained an indigenous r. leguminosarum population of ca. 3 x 10 rhizobia per g of soil. at site i it was necessary to use an inoculum concentration as large as 4 x 10 cfu ml (2 x 10 bacteria seed) to establish the inoculum strain in the majority of nodules (73%). however, at site ii the inoculum st ...	1985	16346769
influence of azospirillum strains on the nodulation of clovers by rhizobium strains.	mixed cultures of several azospirillum and rhizobium trifolii strains caused either an inhibition or stimulation of nodule formation on plant hosts as compared with nodulation of plants inoculated with r. trifolii alone. azospirillum strains affected the nodulation process at a precise cell ratio (r. trifolii/azospirillum cells) and time of inoculation. all azospirillum strains used showed a variation in their ability to inhibit or enhance nodulation by r. trifolii strains. when nonviable cell p ...	1985	16346772
interaction of azospirillum and rhizobium strains leading to inhibition of nodulation.	rhizobium-azospirillum interactions during establishment of rhizobium-clover symbiosis were studied. when mixed cultures of azospirillum and rhizobium trifolii strains were simultaneously inoculated onto clover plants, no nodulation by r. trifolii was observed. r. trifolii anu1030, which nodulated clover plants without attacking root hairs, i.e., does not cause root hair curling (hac), did not show inhibition of nodulation when inoculated together with azospirillum strains. isolation of bacteria ...	1985	16346773
influence of environmental factors on interstrain competition in rhizobium japonicum.	the effect of several biotic and abiotic factors on the pattern of competition between two strains of rhizobium japonicum was examined. in two minnesota soils, waseca and waukegan, strain usda 123 occupied 69% (waseca) and 24% (waukegan) of the root nodules on glycine max l. merrill cv. chippewa. usda 110 occupied 2% of the root nodules in the waseca soil and 12% of the nodules in the waukegan soil. under a variety of other growth conditions-vermiculite, vermiculite amended with waseca soil, and ...	1985	16346786
effect of sym plasmid curing on symbiotic effectiveness in rhizobium fredii.	a mutant, usda 206c, of rhizobium fredii usda 206 was obtained by passage on acridine plates. this mutant was cured of its 197-megadalton sym plasmid but retained its symbiotic effectiveness. multiple plasmid and chromosomally borne nif gene copies have previously been shown in r. fredii usda 206. hindiii and ecori restriction enzyme digests of plasmid and total dna showed that at least two nif gene copies are probably missing in usda 206c. to compare the symbiotic effectiveness of usda 206 and ...	1985	16346803
conserved nodulation genes in rhizobium meliloti and rhizobium trifolii.	plasmids which contained wild-type or mutated rhizobium meliloti nodulation (nod) genes were introduced into nodr. trifolii mutants anu453 and anu851 and tested for their ability to nodulate clover. cloned wild-type and mutated r. meliloti nod gene segments restored anu851 to nod, with the exception of nodd mutants. similarly, wild-type and mutant r. meliloti nod genes complemented anu453 to nod, except for nodcii mutants. thus, anu851 identifies the equivalent of the r. meliloti nodd genes, and ...	1985	16346809
association of rhizobium strains with roots of trifolium repens.	two techniques were used to assess the binding of rhizobia to clover roots: indirect counting after radiolabeling the bacteria and direct counting by using phase-contrast microscopy. microscopic observations revealed a large variability in the number of bacteria associated with individual root hairs. this variability made unbiased counting by microscopy difficult. systematic examination of all visible root hairs and "blind" counting of coded strains and treatments were adopted to minimize observ ...	1985	16346819
survival of bacteria and fungi in relation to water activity and the solvent properties of water in biopolymer gels.	survival of bacteria (rhizobium, agrobacterium, and arthrobacter spp.), fungal spores (penicillium sp.), and yeasts (saccharomyces sp.) was studied in relation to water activity (a(w)) and the presence of nutritive solutes. the cells were entrapped in polysaccharide gels, as is done to immobilize cells or enzymes, and then dehydrated. the number of living cells (10 g of dry polymer) remained constant for periods of storage of >3 years at 28 degrees c when the inocula were kept at an a(w) of <0.0 ...	1985	16346829
rates of drying and survival of rhizobium meliloti strains during storage at different relative humidities.	an investigation was made of the survival of six strains of rhizobium meliloti filtered on membrane filters and held in atmospheres of controlled relative humidities (rh) of from 0 to 100% at 30 degrees c in the presence of air. the rate of water loss in the desiccator was determined by the humidity-controlling solution used. drying was accelerated by a mild evacuation of the desiccator during the drying step. survival rates of r. meliloti strains were much higher after slow drying to 0% rh than ...	1985	16346846
inoculant production with diluted liquid cultures of rhizobium spp. and autoclaved peat: evaluation of diluents, rhizobium spp., peats, sterility requirements, storage, and plant effectiveness.	fully grown broth cultures of various fast- and slow-growing rhizobia were deliberately diluted with various diluents before their aseptic incorporation into autoclaved peat in polypropylene bags (aseptic method) or mixed with the peat autoclaved in trays (tray method). in a factorial experiment with the aseptic method, autoclaved and irradiated peat samples from five countries were used to prepare inoculants with water-diluted cultures of three rhizobium spp. when distilled water was used as th ...	1985	16346860
determination of the hydrogenase status of individual legume nodules by a methylene blue reduction assay.	we adapted a method for the rapid screening of colonies of free-living rhizobium japonicum for hydrogenase activity to determine the hydrogenase status of individual soybean nodules. crude bacteroid suspensions from nodules containing strains known to be hydrogen uptake positive (hup) caused a localized decolorization of filter paper disks, whereas suspensions from nodules arising from inoculation with hydrogen uptake-negative (hup) mutants or strains did not decolorize the disks. the reliabilit ...	1985	16346869
rhizobium sp. degradation of legume root hair cell wall at the site of infection thread origin.	using a new microinoculation technique, we demonstrated that penetration of rhizobium sp. into the host root hair cell occurs at 20 to 22 h after inoculation. it did this by dissolving the cell wall maxtrix, leaving a layer of depolymerized wall microfibrils. colony growth pressure "stretched" the weakened wall, forming a bulge into an interfacial zone between the wall and plasmalemma. at the same time vesicular bodies, similar to plasmalemmasomes, accumulated at the penetration site in a manner ...	1985	16346892
stem and root nodulation in aeschynomene spp.	nodulation ability of 15 rhizobium strains isolated from root and stem nodules of tropical aeschynomene species was studied on 20 different aeschynomene species and four other legumes-arachis hypogaea, stylosanthes guianensis, macroptilium atropurpureum, and sesbania rostrata. the results of this investigation showed that aeschynomene species could be divided into three groups according to the cross-inoculation group concept.	1985	16346895
regulation of nodulation by rhizobium meliloti 102f15 on its mutant which forms an unusually high number of nodules on alfalfa.	a mutant (wl3a150) of rhizobium meliloti 102f51 that elicits an unusually high number of nodules on its host, alfalfa (medicago sativa), supports the idea that the host may rely on early bacteroid development in the nodule or on metabolites produced in the infection thread as one of the signals to control further nodulation. this mutant was initially isolated because of its fix phenotype. it consistently formed many more nodules than all the other fix mutants isolated from strain 102f51 (a total ...	1985	16346908
uptake hydrogenase activity determined by plasmid prl6ji in rhizobium leguminosarum does not increase symbiotic nitrogen fixation.	six mutants of rhizobium leguminosarum 3855 lacking uptake hydrogenase activity (hup phenotype) as a result of tn5-mob mutagenesis of the hup-containing plasmid prl6ji were tested for symbiotic performance on pisum sativum l. and vicia benghalensis l. three pea cultivars and one vetch line, which induce four different levels of hup activity in strain 3855, were grown to flowering under microbiologically controlled conditions in the absence of combined n. direct kjeldahl n measurements showed tha ...	1985	16346912
predominance of fast-growing rhizobium japonicum in a soybean field in the people's republic of china.	soybean rhizobia were isolated from two soils with different cropping histories from hubei province in central china. the first, from honghu county, has been under soybean cultivation for decades. all of the isolates obtained from nodules on soybeans growing in this soil were fast-growing, acid-producing rhizobia. however, slow-growing, alkali-producing isolates were obtained at higher dilutions of the same soil. the second soil, from wuchang county, has been under rice cultivation with no recor ...	1985	16346926
characterization of rhizobia from ineffective alfalfa nodules: ability to nodulate bean plants [phaseolus vulgaris (l.) savi.].	this study was initiated to characterize rhizobium isolates obtained from root nodules of ineffectively nodulated, field-grown alfalfa (medicago sativa l.) plants. the purpose was to determine if these isolates possessed characteristics which would explain either their ineffectiveness in n(2) fixation or their apparent ability to tolerate the moderately acid soil conditions from which they originated. isolates were characterized by analysis of growth rate, 39 degrees c tolerance, acid production ...	1985	16346942
agrocinopine a, a phosphorylated opine is secreted from crown gall cells.	we showed that phosphorus-containing metabolites of crown gall tissues were all taken up by appropriate pti+ agrobacteria. all but one were also taken up by pti- bacteria. this one compound, produced by nopaline-, but not by octopine-type tumours, was the only phosphorylated organic compound actively secreted by healthy crown gall cells, and it appears to be agrocinopine a. testing crown gall cell exudates may be a general procedure for the identification of opines by transformed plant cells.	1985	15926217
monoclonal antibodies to antigens in the peribacteroid membrane from rhizobium-induced root nodules of pea cross-react with plasma membranes and golgi bodies.	three rat hybridoma lines that produced monoclonal antibodies reacting with the peribacteroid membrane from pisum sativum were isolated, and these all appeared to recognize the same antigenic structure. using one of these monoclonal antibodies, afrc mac 64, electron microscopy of immunogold-stained thin sections of nodule tissue revealed that the antigen, present in the peribacteroid membrane, was also found in the plant plasma membranes and in the golgi bodies, but not in the endoplasmic reticu ...	1985	15926221
the use of nuclear-encoded sequences to direct the light-regulated synthesis and transport of a foreign protein into plant chloroplasts.	the light-inducible nuclear gene coding for the small subunit of ribulose-1,5-bisphosphate carboxylase (rubisco), produces a precursor protein with an amino-terminal transit peptide which is transported into the plastids and cleaved by a specific proteinase. to test whether the promoter and transit peptide-coding sequences of the small subunit gene can be used to direct the light-inducible synthesis and transport of a foreign protein into chloroplasts, a chimeric gene was constructed consisting ...	1985	15918225
deletion analysis of rhizobium meliloti symbiotic promoters.	previous examination of dna sequences located 5' to rhizobium meliloti nif transcription units has shown that extensive sequence homology exists among them. here we have examined these reiterated sequences for their role in symbiotic gene regulation. promoter deletion analysis has shown that although an extensive upstream dna sequence 9160 bp) is required for full heterologous activation of the r. meliloti nifhdk promoter by the klebsiella pneumoniae nifa protein in escherichia coli, this region ...	1985	15929217
expression of the nodulation gene nod c of rhizobium meliloti in escherichia coli: role of the nod c gene product in nodulation.	the nod c gene of rhizobium meliloti encodes a protein of mol. wt. 44 000 which is highly conserved in at least three rhizobium species. in order to overproduce this protein, a gene fusion of lambda ci repressor sequences to a large fragment of nod c was constructed. the fusion was placed under control of the tac promoter on plasmid pea305 to yield pjs1035. iptg-induced escherichia coli cells harbouring pjs1035 accumulated the ci-nod c hybrid protein up to 19% of total cellular protein. the synt ...	1985	15929218
promoter analysis of a soybean nuclear gene coding for nodulin-23, a nodule-specific polypeptide involved in symbiosis with rhizobium.	soybean nodulin-23 gene, induced in nodules formed due to symbiosis with rhizobium, was found to contain multiple sequences capable of acting as eucaryotic and procaryotic promoters. the transcription start sites of this gene were localized by s1 nuclease mapping, primer extension with nodule mrna and in vitro run-off transcription analysis. a major transcription start site was observed by s1 mapping; however, the the primer extension revealed a second start site. sequence analysis showed the pr ...	1985	15929219
expression of plant genes during the development of pea root nodules.	the expression of plant genes involved in the pea-rhizobium symbiosis was studied by analysing mrna from root nodules. the rna was translated in vitro and the translation products were separated by two-dimensional gel electrophoresis. the results show differential expression of nodulin genes during root nodule development. one gene encoding n-40' is expressed at a significant level 5 days before the leghemoglobin genes. most other nodulin genes are expressed more of less concomitantly with the l ...	1985	15938045
ecology and genetics of tropical rhizobia species.	biological nitrogen fixation (bnf) technology with special reference to rhizobium-legume symbiosis is growing very rapidly with the hope of combatting world hunger by producing cheaper protein for animal and human consumption in the third world. one can see rapid progress made in the biochemistry and molecular biology of symbiotic nitrogen fixation in general; however, less progress has been made on the ecological aspects despite the fact that an enormous amount of literature is available on ino ...	1985	14544047
nitrogenase reductase: a functional multigene family in rhizobium phaseoli.	the complete coding sequence of the nitrogenase reductase gene (nifh) is present in three different regions of a rhizobium phaseoli symbiotic plasmid. homology between two of the regions containing nifh coding sequences extends over 5 kilobases. these in turn share 1.3 kilobases of homology with the third region. the nucleotide sequences of the three nitrogenase reductase genes were found to be identical. site-directed insertion mutagenesis indicated that none of the three genes is indispensable ...	1985	16593543
nodulin-24 gene of soybean codes for a peptide of the peribacteroid membrane and was generated by tandem duplication of a sequence resembling an insertion element.	a nodulin gene coding for a polypeptide with an apparent m(r) of 24,000 (nodulin-24) was isolated from soybean (glycine max). dna sequence analysis of this gene revealed that its coding capacity is for a polypeptide of only m(r) 15,100 and is interrupted by four introns. the three middle exons and their flanking segments appear to have been generated by duplications of a unit resembling an insertion sequence. this unit is bounded by a 12-base-pair inverted repeat and encompasses the 54-base-pair ...	1985	16593576
conservation of nodulation genes between rhizobium meliloti and a slow-growing rhizobium strain that nodulates a nonlegume host.	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 a rhizobium species. the bacterial strain rp501 is a slow-growing strain of rhizobium isolated from parasponia nodules. strain rp501 also nodulates the legumes siratro (macroptilium atropurpureum) and cowpea (vigna unguiculata). using a cosmid clone bank of rp501 dna, we isolated a 13.4-kilobase (kb) ecori fragment that complemented insertion and p ...	1985	16593600
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 ...	1985	16593624
intra- and interspecies transfer and expression of rhizobium japonicum hydrogen uptake genes and autotrophic growth capability.	cosmids containing hydrogen uptake genes have previously been isolated in this laboratory. four new cosmids that contain additional hup gene(s) have now been identified by conjugal transfer of a rhizobium japonicum 122des gene bank into a tn5-generated hup(-) mutant and screening for the acquisition of hup activity. the newly isolated cosmids, phu50-phu53, contain part of the previously isolated phu1 but extend as far as 20 kilobases beyond its border. phu52 complements five of six hup(-) mutant ...	1985	16578786
identification and genetic analysis of an agrobacterium tumefaciens chromosomal virulence region.	a genetic analysis of agrobacterium tumefaciens chromosomal functions required for virulence was undertaken. large tn5-containing cosmid clones were isolated from dna of avirulent a. tumefaciens mutants having chromosomal tn5 insertions and exhibiting defective attachment to plant cells. the clones from several different mutants each contained overlapping segments of a 30-kilobase a. tumefaciens chromosomal region, which were physically mapped. all chromosomal tn5 insertions leading to the aviru ...	1985	2982791
vector insertion mutagenesis of rhizobium sp. strain ors571: direct cloning of mutagenized dna sequences.	when the limited-host-range plasmid pvp2021 carrying tn5 was mobilized into rhizobium sp. strain ors571 and stable acquisition of tn5 was selected, ors571 plasmid-genome cointegrates were exclusively obtained; direct tn5 transposition was never observed. in every case, genomic cointegrates exhibited an additional (third) is50 element that bordered vp2021 dna sequences but maintained a single tn5 element. genomic cointegrates containing is50 triplications were stable; neither phenotypic reversion ...	1985	2984177
isolation and characterization of transposon tn5-induced symbiotic mutants of rhizobium loti.	rhizobium loti nzp2037 and nzp2213, each cured of its single large indigenous plasmid, formed effective nodules on lotus spp., suggesting that the symbiotic genes are carried on the chromosome of these strains. by using psup1011 as a vector for introducing transposon tn5 into r. loti nzp2037, symbiotic mutants blocked in hair curling (hac), nodule initiation (noi), bacterial release (bar), and nitrogen fixation (nif/cof) on lotus pedunculatus were isolated. cosmids complementing the hac, noi, an ...	1985	2984178
symbiotic mutants of rhizobium meliloti that uncouple plant from bacterial differentiation.	spontaneous mutants at a new symbiotic locus in rhizobium meliloti su47 are resistant to several phages and are conditionally insensitive to a monoclonal antibody to the bacterial surface, apparently because they are deficient in a wild-type exopolysaccharide. on alfalfa, the mutants do not curl root hairs, but penetrate the epidermis directly, forming nodules that contain no visible infection threads or "bacteroids," have a few bacteria in superficial intercellular spaces only and not within th ...	1985	2985267
physical and genetic map of a rhizobium meliloti nodulation gene region and nucleotide sequence of nodc.	infection of alfalfa by the soil bacterium rhizobium meliloti proceeds by deformation of root hairs and bacterial invasion of host tissue by way of an infection thread. we studied an 8.7-kilobase (kb) segment of the r. meliloti megaplasmid, which contains genes required for infection. site-directed tn5 mutagenesis was used to examine this fragment for nodulation genes. a total of 81 r. meliloti strains with mapped tn5 insertions in the 8.7-kb fragment were evaluated for nodulation phenotype on a ...	1985	2985535
repeated sequences similar to insertion elements clustered around the nif region of the rhizobium japonicum genome.	two different repeated sequences (rss) were discovered in the rhizobium japonicum genome: rsrj alpha is 1126 base pairs long and is repeated 12 times; rsrj beta is approximately 950 base pairs long and is repeated at least 6 times. their arrangement in root nodule bacteroid dna is the same as in dna from bacteria grown in culture. deletion analysis showed that many copies of alpha and beta are clustered around the nitrogenase genes nifdk and nifh, or, in general, they are found within a genomic ...	1985	2985537
identification of ptic58 plasmid-encoded proteins for virulence in agrobacterium tumefaciens.	analyses were made of the host-dependent-variation (hdv) locus of the virulence (vir) region of the ptic58 plasmid of agrobacterium tumefaciens. the hdv locus is comprised of at least four genes that encode polypeptides of 13, 15, 29, and 28 kda. insertion of transposon tn5 in the first gene abolishes the expression of all four genes in vitro and in vivo. nucleotide sequence analysis of the hdv locus revealed four open reading frames tandemly arranged with spacer sequences having no promoter-lik ...	1985	2986128
a small mobilizable incp group plasmid vector packageable into bacteriophage lambda capsids in vitro.	a mobilizable cosmid derivative of an incp group plasmid was constructed by cloning the orit region of rk2, a wide host-range plasmid, and the minimal dna sequence of bacteriophage lambda required for efficient packaging in vitro. this cosmid is 13 kb in size and has unique restriction sites for ecori, xhoi, hindiii, and sali. the xhoi and hindiii sites are within the kanamycin-resistance gene and the sali site is in the tetracycline-resistance gene. this plasmid was mobilizable from an escheric ...	1985	2986189
replacement of the deoxycytidine residues in rhizobium bacteriophage rl38ji dna.	rhizobium phage rl38ji dna is resistant to cleavage by a variety of restriction endonucleases, and is only partially sensitive to digestion by pancreatic dnase i or by micrococcal nuclease. we have found that a mixture of dnase i, p1 nuclease, and bacterial alkaline phosphatase will quantitatively digest rl38ji dna to deoxyribonucleosides. hplc analysis revealed that dcyd is nearly totally absent among these digestion products, while dguo, dado, and thd are readily detected. three additional pea ...	1985	2987032
cloning and nucleotide sequence of the tzs gene from agrobacterium tumefaciens strain t37.	the trans-zeatin secretion locus (tzs), from the nopaline ti plasmid of agrobacterium tumefaciens strain t37, was cloned and the nucleotide sequence determined. this gene is located in the virulence region of ptit37. the tzs gene is responsible for the secretion of trans-zeatin into bacterial culture medium and in addition has the cytokinin biosynthetic activity, dimethylallylpyrophosphate:amp dimethylallyltransferase. sequence analysis showed an open reading frame of 729 nucleotides, capable of ...	1985	2987868
tn5 insertions in the agrocin 84 plasmid: the conjugal nature of pagk84 and the locations of determinants for transfer and agrocin 84 production.	the kanamycin-resistance transposon tn5 was randomly introduced into pagk84, a 47.7-kb plasmid coding for agrocin 84 production in agrobacterium. using such marked plasmids, pagk84 was found to be conjugal. it could be transferred to several agrobacterium strains including those harboring octopine- or nopaline-type ti plasmids. its presence has no effect on ti plasmid functions such as opine utilization and tumorigenicity, but it does confer agrocin 84 immunity upon previously sensitive strains. ...	1985	2987991
rhizobium meliloti carries two megaplasmids.	in rhizobium meliloti strain 41 the existence of a second megaplasmid (prme41c) with a molecular weight similar to the sym megaplasmid prme41b was demonstrated. derivatives of the wild-type strain carrying prme41b or prme41c tagged with tn5 allowed the examination of the transfer ability of both megaplasmids. the introduction of megaplasmids into the wild-type r. meliloti was not detected, probably because of the action of plasmid genes coding for entry exclusion of the same type of plasmid. how ...	1985	2987992
slow-growing rhizobium japonicum comprises two highly divergent symbiotic types.	we examined the interrelationships of the genomes of 10 slow-growing strains of rhizobium japonicum to provide a foundation for molecular genetic studies of these agriculturally important endosymbiotic bacteria of commercial soybeans. the degree of base substitution in and around known symbiotic genes (nif and presumptive nod), constitutively expressed genes (glna and reca), and two other cloned sequences was estimated from restriction site variation by using cloned dnas as hybridization probes ...	1985	2989244
expression of symbiotic genes of rhizobium japonicum usda 191 in other rhizobia.	a 200-megadalton plasmid was mobilized from rhizobium japonicum usda 191 to other rhizobium strains either that cannot nodulate soybeans or that form fix- nodules on certain cultivars. the symbiotic properties of the transconjugants indicate that both soybean specificity for nodulation and cultivar specificity for nitrogen fixation are plasmid encoded.	1985	2989250
nitrogen fixation specific regulatory genes of klebsiella pneumoniae and rhizobium meliloti share homology with the general nitrogen regulatory gene ntrc of k. pneumoniae.	we have determined the complete nucleotide sequences of three functionally related nitrogen assimilation regulatory genes from klebsiella pneumoniae and rhizobium meliloti. these genes are: 1) the k. pneumoniae general nitrogen assimilation regulatory gene ntrc (formerly called glng), 2) the k. pneumoniae nif-specific regulatory gene nifa, and 3) an r. meliloti nif-specific regulatory gene that appears to be functionally analogous to the k. pneumoniae nifa gene. in addition to the dna sequence d ...	1985	2989799
a tn3 lacz transposon for the random generation of beta-galactosidase gene fusions: application to the analysis of gene expression in agrobacterium.	the construction and use of a tn3-lac transposon, tn3-hoho1, is described. tn3-hoho1 can serve as a transposon mutagen and provides a new and useful system for the random generation of both transcriptional and translational lacz gene fusions. in these fusions the production of beta-galactosidase, the lacz gene product, is placed under the control of the gene into which tn3-hoho1 has inserted. the expression of the gene can thus be analyzed by monitoring beta-galactosidase activity. tn3-hoho1 car ...	1985	2990912
evidence for plasmid- and chromosome-borne multiple nif genes in rhizobium fredii.	rhizobium fredii is a fast-growing rhizobium isolated from the primitive chinese soybean cultivar peking and from the wild soybean glycine soja. this rhizobium harbors nif genes on 150- to 200-megadalton plasmids. by passage on acridine orange plates, we obtained a mutant of r. fredii usda 206 cured of the 197-megadalton plasmid (usda 206c) which carries both nif and nod genes. this strain, however, has retained its symbiotic effectiveness. probing ecori digests of wild-type and cured plasmid dn ...	1985	2992376
catabolite repression and role of cyclic amp in co2 fixation and h2 metabolism in rhizobium spp.	co2 fixation in rhizobium meliloti was repressed by a variety of organic carbon sources. cellular cyclic amp levels were similar in repressed and nonrepressed cultures. exogenous cyclic amp or additional copies of the adenyl cyclase gene in cells experiencing repression failed to affect the rates of co2 fixation. however, in r. japonicum catabolite repression of h2 utilization was partially circumvented by the presence of the r. meliloti adenyl cyclase gene.	1985	2993243
vectors for transposon mutagenesis of non-enteric bacteria.	we have constructed a series of transposon delivery vectors derived from prk2013. since prk2013 has a broad host range transfer system and a cole1 replicon, it can be transferred to, but not replicated in, many non-enteric gram-negative bacteria. thus prk2013 provides an effective mechanism for the transient introduction of a transposon. delivery vectors containing tn7 (tmp str), tn10 (tet), tn10 hh104 (tet), or tn5-132 (tet) have been constructed. when transposition in caulobacter crescentus wa ...	1985	2993823
analysis of the 5' regulatory region of the gene for delta-aminolevulinic acid synthetase of rhizobium meliloti.	transcriptional regulation of the delta-aminolevulinic acid synthetase gene of rhizobium meliloti was investigated under conditions of normal vegetative growth and during symbiosis with the legume host alfalfa. s1 nuclease mapping and dna sequence analysis indicated that transcription originates from two sites separated by 238 base pairs. a deletion analysis of the putative promoter regions p1 and p2, corresponding to the proximal and distal rna start sites, was carried out with bal-31 nuclease. ...	1985	2994020
lacz gene fusions and insertion mutagenesis in the tl-region of agrobacterium rhizogenes ri plasmid.	agrobacterium rhizogenes induces root formation and inserts a fragment of its plasmid into the genome of infected plants. a part of the transferred region (tl-region) of the ri plasmid of a. rhizogenes strain a4 was cloned in pbr322. insertions of the escherichia coli lacz coding region into the hybrid plasmids were made in vivo using mini-mu-duction. two mini-mus were used, one with the mu a and b transposase genes (mudii1681) and the other without (mudii1734). two inserts which result in e. co ...	1985	2994128
expression of a rhizobium phaseoli sym plasmid in r. trifolii and agrobacterium tumefaciens: incompatibility with a r. trifolii sym plasmid.	identification of the sym plasmid in rhizobium phaseoli strain rcc3622 is described. introduction of this plasmid into r. trifolii or agrobacterium tumefaciens strains resulted in bacteria capable of forming characteristic spherical root nodules on beans. this sym plasmid, designated psym9, was characterized as 275 mda and nonconjugative. psym9 was incompatible with the r. trifolii sym plasmid psym5, and carries genes determining a melanin-like black pigment. a second plasmid of 135 mda, prph362 ...	1985	2994130
plasmid fingerprinting. a tool for bacterial strain identification and surveillance of nosocomial and community-acquired infections.	plasmid fingerprinting provides a rapid and dependable means of identifying bacterial isolates of the same strain. the stability, wide distribution, and diverse nature and size of extrachromosomal elements make it suitable for virtually all bacterial genera. there are many different procedures available for plasmid screening, and the one chosen depends primarily on the types of organisms to be analyzed. some procedures are better suited to gram-positive organisms; others are better for visualizi ...	1985	2994942
cryptic plasmid and rifampin resistance in rhizobium meliloti influencing nodulation competitiveness.	an assessment was made of the relative contributions of a spontaneous mutation to rifampin resistance and a cryptic plasmid, pta2, to competitive nodulation of medicago sativa by a strain of rhizobium meliloti. this was facilitated by use of rifampin-resistant derivatives of this strain in which pta2 was originally present, cured, or reintroduced. both curing of pta2 and spontaneous mutation to rifampin resistance significantly influenced nodulating competitiveness, but the effect of rifampin re ...	1985	2995316