Morphological variations of Haemophilus parasuis strains.
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Haemophilus parasuis strains isolated from the noses of apparently healthy animals and from animals with pathological conditions were examined for the presence of a capsule, for their ability to agglutinate in acriflavine or after boiling, and for their peptide profile after polyacrylamide gel electrophoresis (PAGE). The capsule was identified by precipitation against hexadecyl trimethylammonium bromide (Cetavlon), by demonstration of iridescence, and by means of a capsule-staining method. We found a group of capsulated strains showing a rather coccobacillary morphology compared with the morphology with polymorphism, varying from rod-like to filamentous, in strains without detectable capsules. The strains of the latter group were agglutinated by acriflavine or by boiling. Soluble antigens of capsulated strains reacting with Cetavlon were thermostable and resisted proteolytic enzymes, thus suggesting the presence of an acidic polysaccharide. A few of the capsulated strains did not precipitate with Cetavlon, which indicated that their chemical composition was different. Acriflavine-positive strains belonging to a definite PAGE pattern (type II) seemed to be associated with pathological conditions more frequently than were capsulated strains which were mostly isolated from nasal cavities of apparently healthy pigs. We put forward the hypothesis that the agglutinability in acriflavine, together with the PAGE profile type II, may be associated with particular structures responsible for virulence. (+info)
Bacteriophage T4 alt gene maps between genes 30 and 54.
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Two- and three-factor crosses proved that the T4 alt gene, which codes for a virion-associated NAD+:protein ADP-ribosyltransferase, is located between genes 30 and 54. (+info)
Identification of type D Pasteurella multocida by counterimmunoelectrophoresis.
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A counterimmunoelectrophoresis (CIE) test was applied to serotype 35 isolates of type D Pasteurella multocida recovered from 32 cases of atrophic rhinitis (in swine) and 3 cases of snuffles (in rabbits). The CIE test was compared with the indirect hemagglutination (IHA) and acriflavine (AF) tests. Results of the CIE test correlated 100% with those of the IHA test whereas results of the AF test correlated 91.43% with those of the IHA test. The CIE test was rapid and simpler to perform compared with the IHA test and more sensitive than the AF test. Cross-reactions were not encountered with capsular antigens of P. multocida types A, B, and E in the CIE test. The CIE test was not found to be suitable for typing type A P. multocida strains. (+info)
Induction of antibiotic production with ethidium bromide in Streptomyces hygroscopicus.
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Protoplast regeneration carried out in a carriomycin producing organism, Streptomyces hygroscopicus 358 AV2, lose carriomycin productivity without loss of carriomycin-resistance and the ability of formation of aerial mycelium. Ethidium bromide treatment on the 358 AV2 strain generated a bald mutant that produced carriomycin and a new antibiotic curromycin. In some other media, however, the parent strain produced curromycin, indicating that the ethidium bromide treatment altered the regulation of antibiotic production. Ethidium bromide treatment on a protoplast-regenerated strain derived from the parent strain resulted in derivatives capable of producing carriomycin and curromycin. These strains were unstable and tended to lose the recovered antibiotic productivity easily. (+info)
Novel acriflavin resistance genes, acrC and acrD, in Escherichia coli K-12.
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Acriflavine-resistant mutants were isolated from an acriflavine-sensitive (acrA) strain of Escherichia coli K-12 and then tested for temperature sensitivity of cell division. Genetic analysis characterized two new genetic loci, acrC and acrD. The former was mapped between tonA and proA, and the latter between the origin of genetic transfer of HfrH and serB. acrC and acrD mutants could divide but did not initiate a new round of deoxyribonucleic acid (DNA) replication at 43 degrees C. DNA synthesis of the acrC mutant cells ceased after a period of time following temperature shift-up, and thereafter DNA degradation occurred. However, cell mass continued to increase for a long time at the nonpermissive temperature. On the other hand, DNA synthesis of the acrD mutant cells ceased soon after the shift-up, and the cell mass did not appreciably increase during the prolonged incubation. (+info)
Inhibition of deoxyribonucleic acid repair in Escherichia coli by caffeine and acriflavine after ultraviolet irradiation.
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The effects of caffeine and acriflavine on cell survival, single-strand deoxyribonucleic acid break formation, and postreplication repair in Escherichia coli wild-type WP2 and WP2 uvrA strains after ultraviolet irradiation was studied. Caffeine (0.5 mg/ml) added before and immediately after ultraviolet irradiation inhibited single-strand deoxyribonucleic acid breakage in wild-type WP2 cells. Single-strand breaks, once formed, were no longer subject to repair inhibition by caffeine. At 0.5 to 2 mg/ml, caffeine did not affect postreplication repair in uvrA strains. These data are consistent with the survival data of both irradiated WP2 and uvrA strains in the presence and absence of caffeine. In unirradiated WP2 and uvrA strains, however, a high caffeine concentration (greater than 2 mg/ml) resulted in gradual reduction of colony-forming units. At a concentration insufficient to alter survival of unirradiated cells, acriflavine (2 microgram/ml) inhibited both single-strand deoxyribonucleic acid breakage and postreplication repair after ultraviolet irradiation. These data suggest that although the modes of action for both caffeine and acriflavine may be similar in the inhibition of single-strand deoxyribonucleic acid break formation, they differ in their mechanisms of action on postreplication repair. (+info)
Acriflavine-binding capacity controlled by the acrA gene of Escherichia coli.
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The acrA mutation in Escherichia coli led to a substantial increase of the acriflavine-binding capacity of the cell, whereas the related mutations acrB (gyrB) and arcC did not. Metal ions such as Na+, K+, Mg2+, Ca2+ and Al3+ effectively released the bound acriflavine, in proportion to their ionic strengths. The presence of cations, in fact, increased the survival fraction of the cells in the acriflavine-containing medium. Polymyxin B, an antibiotic which binds to membrane phospholipid, competed with acriflavine for binding sites. Cell wall digestion by treatment with lysozyme and EDTA slightly decreased the acriflavine-binding capacity. Almost no difference was observed in acriflavine-binding capacity between intact cells and cells from which lipopolysaccharide has been extracted (46.9% removed from the acrA cells and 47.4% from the acrA+ cells). Acriflavine bound to the cells was most effectively extracted by ethanol containing 1% HCl or by 2% (w/v) SDS. The difference in the acriflavine-binding capacity between the acrA and acrA+ cells was also observed in the spheroplasts. These facts indicate a relationship between the acrA gene product and the acriflavine-binding capacity of the cells. (+info)
The growth-inhibitory effects of some dyes on different Mycoplasma and Acholeplasma spp.
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A microtitre-plate method for evaluating the inhibitory effect of dyes on the growth of mycoplasmas in fluid medium is described. Different species were shown to differ in their sensitivity to dyes. Statistical analysis (a) compared the general sensitivity and resistance of different mycoplasma species to the dyes and (b) showed that the dyes fell into two main groups in their effects on the mycoplasma species. (+info)