RESUMEN
Induction of precise excision of Tn10 by UV or mitomycin C (MMC) is dependent on the expression of the SOS system. Ruv mutants of Escherichia coli, which are defective in DNA repair and recombination, showed diminished frequencies of both spontaneous and UV- or MMC-induced excision of Tn10 inserted in gal. RecG mutants, which are also defective in DNA repair and recombination, showed decreased induction of Tn10 excision with MMC, but not after UV treatment. A recG ruv double mutant showed a greater decrease in induction of excision with MMC than either single mutant. One can speculate that the Ruv proteins, which are known to be involved in the resolution of Holliday junctions, might also be involved in the resolution of putative intermediates generated during the precise excision of Tn10. RecG protein, whose function partially overlaps those of Ruv proteins, might also have some role in this process.
Asunto(s)
Proteínas Bacterianas/genética , Elementos Transponibles de ADN , Proteínas de Escherichia coli , Escherichia coli/genética , Mitomicina/farmacología , Mutágenos/farmacología , Mutación , Rayos UltravioletaRESUMEN
To re-evaluate the usefulness of the IgM fluorescent treponemal antibody absorption test in the diagnosis of congenital syphilis, three groups of infants were investigated. Group 1 infants showed that the test was always negative in normal neonates born to seronegative mothers. From Group 2 infants we determined the standardization of the test using commercially prepared conjugate to allow the maximum exclusion of false positive and negative results. Studies on Group 3 neonates confirmed that the standardized test was extremely successful in determining whether or not an asymptomatic infant was infected with Treponema pallidum. Finally it was shown that the standardization of the test varies with different commercially prepared conjugates. From the investigation it was concluded that the IgM FTA test, if suitably standardized, was a highly successful method for diagnosing congenital syphilis, especially in asymptomatic neonates.