Reversed-phase chromatography of novel biologically effective aminoacridine-N-glycosides by OPLC.
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The reversed-phase chromatographic behavior of novel biologically active aminoacridine-N-glycosides is studied. The chromatographic experiments are performed with overpressurized layer chromatography. Weak ion pairs are formed with methanesulfonic acid, but only at low concentrations of the ion-pairing reagent. The retention seems to involve a reversed-phase mechanism. The base compounds only slightly modify the retention, while the number and polarity of the substituents have larger effects. The pH dependence of the retention is very typical for the aminoacridine-N-glycosides, and it plays an important role in the separation. The monoglycosides are completely separated from the corresponding base compounds, as are the diglycosides from the monoglycosides, on RP-2, RP-8, and RP-18 layers with eluents containing 30 to 60% acetonitrile and at least 0.005 M ammonium carbonate at pH 4 to 6. (+info)
Induction and characterization of mitochondrial DNA mutants in Chlamydomonas reinhardtii.
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In addition to lethal minute colony mutations which correspond to loss of mitochondrial DNA, acriflavin induces in Chlamydomonas reinhardtii a low percentage of cells that grow in the light but do not divide under heterotrophic conditions. Two such obligate photoautotrophic mutants were shown to lack the cyanide-sensitive cytochrome pathway of the respiration and to have a reduced cytochrome c oxidase activity. In crosses to wild type, the mutations are transmitted almost exclusively from the mating type minus parent. A same pattern of inheritance is seen for the mitochondrial DNA in crosses between the two interfertile species C. reinhardtii and Chlamydomonas smithii. Both mutants have a deletion in the region of the mitochondrial DNA containing the apocytochrome b gene and possibly the unidentified URFx gene. (+info)
Expression of the cloned ColE1 kil gene in normal and Kilr Escherichia coli.
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The kil gene of the ColE1 plasmid was cloned under control of the lac promoter. Its expression under this promoter gave rise to the same pattern of bacterial cell damage and lethality as that which accompanies induction of the kil gene in the colicin operon by mitomycin C. This confirms that cell damage after induction is solely due to expression of kil and is independent of the cea or imm gene products. Escherichia coli derivatives resistant to the lethal effects of kil gene expression under either the normal or the lac promoter were isolated and found to fall into several classes, some of which were altered in sensitivity to agents that affect the bacterial envelope. (+info)
Second acriflavine sensitivity mutation, acrB, in Escherichia coli K-12.
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A novel acriflavine-sensitive mutant was isolated. The mutation was referred to as acrB1 and was demonstrated to be located at min 82. (+info)
Genetic instability in auxotrophs of Salmonella typhimurium requiring cysteine or methionine and resistant to inhibition by 1,2,4-triazole.
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Triazole-resistant (Trz(r)) derivatives of six cysteine- or methionine-requiring (Cym(-)) mutants of Salmonella typhimurium were isolated. Some of the derivatives of each mutant (CTS) were prototrophic, i.e., Cym(-) was suppressed. In every case suppression was initially unstable, Cym(-) auxotrophs being segregated at high frequency, although Trz(r) was stable. After several subcultures on selective medium, CTS strains were classified as either persistently unstable or stabilized. The unstable strains segregated Cym( -) auxotrophs at frequencies of 50-70%, whereas the stabilized strains segregated at frequencies of less than 1%. All suppressed strains had a stable Trz(r) marker co-transducible with cysA. However, there was a correlation between the class of CTS strain and Cym(- ) phenotype. The stabilized strains were Cym(+), whereas the unstable strains were Cym(-). Acriflavin and ethidium bromide increased segregation in the unstable strains, suggesting the involvement of a plasmid. The stabilized strains were refractory to the curing agents. There was no detectable change in the quantity or quality of the S. typhimurium cryptic plasmid. The Trz(r) phenotype of the CTS strains suggested that Trz(r) mutations were of the stable TrzA type. It is suggested that correction of the Cym(-) lesions in CTS strains results from an insertion within the cysCDHIJ gene cluster of a DNA species originating in the cysALKptsHI region of the S. typhimurium chromosome. (+info)
Virulence markers of mesophilic aeromonads: association of the autoagglutination phenomenon with mouse pathogenicity and the presence of a peripheral cell-associated layer.
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Autoagglutination (AA phenotype) of mesophilic aeromonads in broth was found to be a virulence-associated marker. There were two kinds of AA+ strains: those that spontaneously pelleted (SP+), and those that pelleted only after boiling (PAB+). Of 79 strains tested, 24 (30%) were AA+, and 18 of these were recovered from clinical specimens. Most of the AA+ strains (n = 21) were identified as either Aeromonas sobria or Aeromonas hydrophila. Of the well-documented clinical isolates of A. sobria and A. hydrophila available, 5 (46%) of 11 from invasive disease and 4 (14%) of 29 from noninvasive disease were SP- PAB+. The SP- PAB+ phenotype was significantly associated with invasive infections (e.g., bacteremia and peritonitis [chi 2, P less than 0.05]). All seven of the SP- PAB+ A. sobria and A. hydrophila strains tested killed mice within 48 h after intraperitoneal infection with 1 x 10(7) to 3 x 10(7) CFU, whereas only two of four SP+ PAB+ strains tested were lethal. All of the SP- PAB+ A. sobria and A. hydrophila isolates examined shared common O somatic antigens and possessed an external layer peripheral to the cell wall as determined by thin-section electron micrography. The LL1 strain of A. hydrophila used by Dooley et al. (J. S. G. Dooley, R. Lallier, and T. J. Trust, Vet. Immunol. Immunopathol. 12:339-344, 1986) to demonstrate an S membrane protein component in aeromonads virulent for fish also was SP- PAB+ and possessed the peripheral membrane, suggesting an association between these two components. Seven AA- and three SP+ strains tested lacked this layer; furthermore, 22 (71%) of 31 such isolates did not kill mice. The AA phenotype was a stable characteristic upon long-term passage of isolates in vitro. Study of SP+ and PAB+ aeromonads by surface charge and hydrophobicity analyses indicated that neither property correlated with either virulence or the presence of an external layer. (+info)