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ELIMINATION OF GENETIC ELEMENTS GOVERNING COMPETENCE IN TRANSFORMATION OF NEISSERIA MENINGITIDIS BY TREATMENT WITH ETHIDIUM BROMIDE AND ACRIFLAVIN
Author(s) -
Jyssum Kaare
Publication year - 1971
Publication title -
acta pathologica microbiologica scandinavica section b microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0365-5563
DOI - 10.1111/j.1699-0463.1971.tb02153.x
Subject(s) - ethidium bromide , neisseria meningitidis , plasmid , dna , microbiology and biotechnology , transformation (genetics) , reversion , biology , mutant , strain (injury) , chemistry , genetics , gene , bacteria , phenotype , anatomy
Competence in the DNA‐mediated transformation of Neisseria meningitidis Strain M1 and Strain Ne15 depends upon a heritable factor called cp . Ethidium bromide was found to be a powerful agent in eliminating competence in genetically competent ( cp +) variants of the two strains. The strain Ne15 could also be rendered genetically incompetent ( cp ‐ ) by acriflavin at low frequencies. When suspensions of meningococci were treated with ethidium bromide, the frequency of streptomycin resistant mutants could be increased around ten‐fold above the spontaneous frequency. With acriflavin the frequency could be increased approximately two‐fold. Both drugs seemed preferentially to mutagenize at the replication point of the chromosome. The mutagenic effect as well as the killing effect of ethidium bromide and acriflavin was higher in cp + variants than in cp ‐ ones. In growing cultures a mutagenic effect of ethidium bromide could also be demonstrated, whereas no significant mutagenic effect of acriflavin could be found. The inhibiting effect of the two drugs seemed to be the same in growing cultures of cp + variants as it was in cultures of cp ‐ variants. The findings from N. meningitidis have been discussed in relation to the action of these dyes on various genetic determinants of plasmid type in other microbes.