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S K Farrand

Publications and source records attributed to S K Farrand.

84 records · Page 5Linked to original sources
PubMed1980

Diversity among B6 strains of Agrobacterium tumefaciens.

A total of 20 laboratory substrains of Agrobacterium tumefaciens strain B6 were compared with respect to six characteristics, including 3-ketolactose production, lysogeny, octopine catabolism, tumorigenic host range, and plasmid content. Within this group of strains diversity was found for all characteristics except 3-ketolactose production. Six substrains were lysogenized with an omega-type phage, whereas one substrain appeared neither sensitive to nor lysogenized with this bacteriophage. All but two substrains catabolized octopine and induced tumors on carrot disks. These 18 substrains harbor deoxyribonucleic acid sequences homologous to pTiB6-806. The two substrains unable to catabolize octopine were nontumorigenic and lacked detectable Ti plasmid sequences. Of the 20 substrains, 13 also contained sequences homologous to the cryptic plasmid pAtB6-806; 2 of the 18 substrains tumorigenic on carrots failed to induce tumors on Kalanchoe leaves. Their inability to induced tumors on this host, could not be correlated with lysogeny, with the presence or absence of pAtB6-806, or with the very large cryptic plasmid recently described. The Ti plasmids from these two strains were indistinguishable from pTiB6-806 by restriction enzyme analysis and could genetically convert a cured A. tumefaciens strain to tumorigenicity on both plant species. The results with these two strains suggest that parameters of tumorigenicity, such as host range, may be controlled by the bacterial chromosome.

Arginine↗
PubMed1979

Hospital isolates of Serratia marcescens transferring ampicillin, carbenicillin, and gentamicin resistance to other gram-negative bacteria including Pseudomonas aeruginosa.

Thirteen independent isolates of Serratia marcescens associated with nosocomial urinary tract infections were obtained from the clinical microbiology laboratory at Hines Veterans Administration Hospital. The isolates were resistant to at least ampicillin, carbenicillin, gentamicin, and tobramycin. They could be divided into two groups on the basis of their antibiotypes. Group I (9 strains) showed resistance to 13 antibiotics, including 3 beta-lactams, 6 aminoglycosides, tetracycline, sulfonamide, trimethoprim, and polymyxin B. Group II (4 strains) was resistant to 11 antibiotics, including 3 beta-lactams, 5 aminoglycosides, sulfonamide, trimethoprim, and polymyxin B. Donors from both groups transferred resistance traits to Escherichia coli. Transconjugants from matings with group II donors all acquired resistance to nine antibiotics, including the three beta-lactams, five aminoglycosides, and sulfonamide. Transconjugants from matings with group I donors were of varied antibiotypes, inheriting resistance to up to 11 of the 13 antibiotics. Resistances to trimethoprim and polymyxin B were never observed to transfer. E. coli transconjugants of each group were capable of transferring multiple-antibiotic resistance to several other members of the family Enterobacteriaceae. All group II S. marcescens and E. coli donors and all group I S. marcescens donors transferred carbenicillin, streptomycin, kanamycin, gentamicin, tobramycin, and sisomicin resistance to Pseudomonas aeruginosa. The results suggest that these S. marcescens strains harbor R factors of a broader host range than previously reported.

Ampicillin↗
PubMed1979

R-plasmid-mediated chromosomal gene transfer in Agrobacterium tumefaciens.

Although several techniques are available for transferring the Ti plasmids from one strain of agrobacterium tumefaciens to another, there are no reproducible methods for analysis of chromosomal markers in this phytopathogen. The R plasmid, R68.45, is known to show chromosomal mobilizing ability in several bacterial genera including the closely related Rhizobia. R68.45 was transferred into the prototrophic A. tumefaciens strain 15955. Ten kanamycin-resistant transconjugant clones were tested for chromosomal mobilizing ability by mating with strain SA10, rifampin- and streptomycin-resistant histidine auxotroph of strain 15955. Of the 10 donor clones, 2 showed high chromosomal mobilizing ability. Between 1,000 and 2,000 His+ colony-forming units per ml were obtained, a value 10 to 20 times greater than can be accounted for by spontaneous reversion. Sequential recloning and matings resulted in the isolation of relatively stable donor cultures. Chromosome gene transfer is dependent upon the presence in the donor of R68.45. Donors lacking an R plasmid or harboring the closely related plasmid RP4 failed to yield His+ transconjugants. With strain SA11, a methionine auxotroph of strain SA10, coinheritance of histidine and methionine independence could be demonstrated. Approximately half of the transconjugants also inherited R68.45. These results indicate that A. tumefaciens 15955 is capable of undergoing host chromosomal genetic exchange.

Chromosomes, Bacterial↗
PubMed1976

RP4 promotion of transfer of a large Agrobacterium plasmid which confers virulence.

Introduction of RP4 plasmid into Agrobacterium tumefaciens promotes the transfer on solid medium of large virulence-associated plasmids from virulent donor strains to a plasmidless avirulent recipient. Exconjugants were selected for the ability to utilize octopine or nopaline as the sole source of arginine, traits which are coded for by virulence-associated plasmids in the strains employed here. All exconjugants retained the arginine auxotrophy of the recipient strain, and were resistant to ampicillin and kanamycin, drugs to which RP4 confers resistance. Five exconjugant clones from one cross were shown by alkaline sucrose gradient analysis to contain both RP4 plasmid and the large virulence-associated plasmid of the donor strain. All five exconjugants exhibited virulence on carrot, sunflower and kalanchoe plants. These results indicate that virulence and the ability to degrade octopine are plasmid-borne traits in A. tumefaciens strains 15955 and A6, and extend the evidence that large plasmids in A. tumefaciens are vectors of virulence genes.

Arginine↗
PubMed1976

Conjugation in Agrobacterium tumefaciens in the absence of plant tissue.

A general, reliable conjugation system for Agrobacterium tumefaciens in the absence of plant tissue is described in which A. tumefaciens can serve either as the donor or recipient of plasmid deoxyribonucleic acid with reasonable efficiency. Plasmid RP4 was transferred from Escherichia coli to A. tumefaciens and from strain of A. tumefaciens. Both RP4 and the A. tumefaciens virulence-associated plasmids were detected by alkaline sucrose gradients in A. tumefaciens strains A6 and C58 after mating with E. coli J53(RP4). The pathogenicity (tumor foramtion) of strains A6 and C58 and the sensitivity of strain C58 to bacteriocin 84 were unaffected by the acquistion of RP4 by the Agrobacterium strains. Plasmid R1drd-19 was not transferred to A. tumefaciens. Transformation experiments with plasmid deoxyribonucleic acid were unsuccessful, even though, in the case of RP4, conjugation studies showed taht the deoxyribonucleic acid was compatible with that of the recipient strains.

Anti-Bacterial Agents↗
PubMed1975

Attempts to detect Agrobacterium tumefaciens and bacteriophage PS8 DNA in crown gall tumors by DNA-DNA-filter hybridization.

A systematic study of the DNA-DNA-filter reaction is presented which measures its ability to detect small amounts of simple DNA (bacterial or bacteriophage) in model mixtures of DNA immobilized on filters. Saturation curves show qualitatively that significant binding occurs when there is 10% Agrobacterium tumefaciens DNA on the filter but not 1%. PS8 bacteriophage DNA is detectable at a level of 0.1%. True saturation is not attained in the bacterial DNA reaction : radioactivity bound represents only 3% of the theoretical saturation value. The bacteriophage DNA reactions attain 15-30% of the expected saturation value. When crown gall tumor DNA filters were tested for the presence of A. tumefaciens or PS8 bacteriophage DNA by saturation reactions, an apparently significant amount of binding was observed compared with usual background levels for heterologous DNA filters. However thermal dissociation profiles revealed that no well-matched duplexes were formed. Normal tobacco callus DNA filters exhibited the same type of binding of labeled DNA to a similar extent (50-100% as much as tumor DNA filters). Both types of DNA-filters bound Bacillus subtilis and bacteriophage T4 DNA as efficiently as A. tumefaciens and PS8 DNA. The high non-specific background binding of labeled DNA by filters containing DNA isolated from plant tissue culture materials is ascribed to low single strand molecular weight of the filterbound DNA. This study provides no evidence for foreign DNA in crown gall tumors, and raises objections to the interpretation of the data of earlier investigators (Quetier, F., Huguet, T. and Guille, E. (1969) Biochem, Biophys. Res, Commun. 34, 128-133 and Srivastava, B.I.S. (1970) Life Sci. 9, 889-892) who claimed to detect A. tumefaciens DNA in crown gall tumors by DNA-DNA-filter hybridization.

Bacteriophages↗
PubMed1974

Agrobacterium tumefaciens DNA and PS8 bacteriophage DNA not detected in crown gall tumors.

Renaturation kinetics of labeled Agrobacterium tumefaciens DNA are not influenced by addition of 10(4)-fold excess of crown gall tumor DNA. Reconstruction experiments demonstrated that 0.01% added bacterial DNA produces a detectable increase in rate of renaturation of labeled DNA. Crown gall tumor DNA therefore cannot contain as much as 0.01% A. tumefaciens DNA (one entire bacterial genome per three diploid tumor cells). By the same technique, PS8 bacteriophage DNA is not detected in crown gall tumor DNA under conditions that allow detection of 0.0007-0.001% added phage DNA. Crown gall tumor DNA cannot contain as much as one entire phage genome per diploid tumor cell. The presence of a small fraction of either genome (less than 5%), even if present as multiple copies, would escape detection by this method.

Bacteriophages↗
PubMed1974

Attempts to detect deoxyribonucleic acid from Agrobacterium tumefaciens and bacteriophage PS8 in crown gall tumors by complementary ribonucleic acid-deoxyribonucleic acid-filter hybridization.

Labeled ribonucleic acid (RNA) complementary to Agrobacterium tumefaciens DNA and PS8 bacteriophage DNA (cRNA) were used in a systematic study of the sensitivity of cRNA/deoxyribonucleic acid (DNA)-filter hybridization for detection of small amounts of phage or bacterial DNA immobilized on filters. A. tumefaciens cRNA of specific activity 10(6) to 2 x 10(6) counts per min per mug reacted to a significant extent when the DNA-filter contained 1% A. tumefaciens DNA in a salmon DNA background, but 0.1% A. tumefaciens DNA was not detectable. PS8 phage cRNA of the same specific activity reacted to a significant extent when the DNA-filter contained as little as 0.01% PS8 DNA in a salmon DNA background. Both kinds of cRNA were found to bind to tobacco crown gall tumor DNA-filters. Similar reaction was found with control normal callus DNA-filters but not with tobacco seedling DNA-filters. The "hybrids" formed by cRNA with normal callus and tumor DNA-filters had low thermal stability. Attempts to purify the tumor and normal callus DNA prior to immobilization on the filter resulted in elimination of this spurious binding. No evidence was found for bacterial or phage DNA in crown gall tumor DNA.

Bacteriophages↗
PubMed1973

Pleiotropic menaquinone-deficient mutant of Bacillus subtilis.

A multiple aromatic amino acid auxotroph of Bacillus subtilis 168 has been isolated which is unable to synthesize menaquinone-7 (MK-7) unless supplied with shikimic acid (SHK). The mutant, RB163, was isolated by selecting for resistance to low levels (1.5 mug/ml) of kanamycin. Enzymatic and genetic analyses show that the strain is an aroD mutant lacking 5-dehydroshikimate reductase. Under growth conditions in which its MK-7 deficiency is expressed, RB163 is deficient in cytochromes a, b, and c, exhibits low growth yields, and does not sporulate. Genetic analysis indicates that this pleiotropic phenotype is the result of a single genetic event. All phenotypic characteristics are reversible when the mutant is grown under conditions such that MK is synthesized. Comparison of strain RB163 with other aro mutants blocked before SHK ("early-aro" mutants) reveals interesting differences. Most early-aro mutants are cytochrome- and MK-sufficient, sporogenous, and sensitive to kanamycin when grown in the absence of SHK. However, in addition to strain RB163, two other aro mutants were found to show the pleiotropic phenotype. These three mutants have in common, and differ from other early-aro strains in, the inability to synthesize MK. It is suggested that the phenotypically wild-type aro mutants are bradytrophic, allowing enough substrate flow through the common aromatic pathway to satisfy the MK requirement. The pleiotropic mutants are thought to be completely blocked in the common pathway, thus accounting for their inability to synthesize MK.

Alcohol Oxidoreductases↗
PubMed1973

Physiological effects of menaquinone deficiency in Bacillus subtilis.

Several aspects of the respiratory physiology of a mutant of Bacillus subtilis deficient in menaquinone-7 (MK-7) and in cytochromes were investigated. The mutant, an aromatic amino acid auxotroph blocked at dehydroshikimate reductase, is unable to synthesize MK-7 unless grown in the presence of the common aromatic amino acid intermediate, shikimate. The inability to synthesize MK-7 prevents the mutant from expressing the normal postexponentialphase cytochrome phenotype. When grown in the presence of shikimate, normal levels of these electron transport components are formed. It was found that the intracellular concentration of MK-7 could be predictably regulated by growing the cells with known concentrations of exogenous shikimate. When the mutant was grown under conditions where MK-7 biosynthesis was severely limited, there was a decrease in oxygen uptake and in membrane-associated reduced nicotinamide adenine dinucleotide (NADH) oxidase and succinate oxidase activity. NADH oxidase, but not succinoxidase, could be restored in membrane preparations by the addition of menadione to the reaction mixture. Reduced-minus-oxidized cytochrome difference spectra indicate that an MK-7 deficiency limits electron flow through the cytochrome chain. Furthermore, oxidation-reduction patterns suggest that MK-7 functions between the primary dehydrogenases and the cytochromes. Although the mutant is asporogenous when grown under conditions where MK-7 biosynthesis is limited, the inability to sporulate does not appear to result from lesions in the electron transport system.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Localization and characterization of the region encoding catabolism of mannopinic acid from the octopine-type Ti plasmid pTi15955.

The region of the octopine-type tumor-inducing (Ti) plasmid pTi15955 encoding catabolism of mannopinic acid was localized to an 18-kilobase (kb) segment mapping between Ti plasmid coordinates 70 and 88. A subclone containing only this region normally did not allow utilization of any other mannityl opine. However, spontaneous mutants of the plasmid were isolated that conferred catabolism of agropinic acid. While the mutants remained regulated for mannopinic acid utilization, induction by this opine resulted in increased activity associated with agropinic acid catabolism. Respirometric studies and results from growth assays on mannopinic acid analogues indicated that the genes encoded on the 18-kb subclone were regulated in a wild-type fashion. By means of these analogues, spontaneous constitutive mutants were isolated. In several cases, the mutant phenotype was associated with an insertion event mapping within a 300-base pair region of the subclone insert. Although constitutive for catabolism of mannopinic acid, these mutants remained unable to catabolize any of the other mannityl opines. Segregation studies and genetic reconstitution experiments showed that one of the subclones isolated directly in Agrobacterium was actually composed of two complementing recombinant plasmids contained in the same cell. This indicated that the genes encoding mannopinic acid catabolism were organized into at least two complementation groups. These results point to a high degree of complexity in the organization and regulation of Ti plasmid genes encoding catabolism of a relatively simple carbon source.

DNA Restriction Enzymes↗