RESUMO
Constitutive overexpression of Cyp6g1 and Cyp6a2 genes in DDT-resistant line Oregon-flare of the Drosophila melanogaster wing spot test (SMART) has been reported. Cyp6g1 and Cyp6a2 expression levels were compared against the ß-actin gene in the standard (ST) and high bioactivation (HB) crosses of the Somatic Mutation and Recombination test (SMART) treated with sulforaphane or phenobarbital as the control inductor. The CYP450s' enzymatic activity was determined by overall NADH consumption. The expression levels of both genes and the CYP450s activity was higher in the HB cross. The Cyp6g1 levels were higher than those of Cyp6a2 in both crosses, but lower than the expression of ß-actin. Sulforaphane decreased Cyp6g1 in the HB cross and increased it in the ST cross; Cyp6a2 expression was inhibited in the ST cross. Sulforaphane resulted mutagenic in the ST cross, which could be related to the inhibition of Cyp6a2. Phenobarbital did not modify the Cyp6g1 levels but increased the Cyp6a2 and CYP450s basal activity. Although the transcript levels were always higher in the HB cross than in the ST, the expression of Cyp6a2 and Cyp6g1 was not constitutive and was independent one from the other. Sulforaphane modulated both genes in a differential way in each cross and, in contrast to its putative protective effect, it resulted to be mutagenic.
Assuntos
Anticarcinógenos/farmacologia , Sistema Enzimático do Citocromo P-450/biossíntese , Proteínas de Drosophila/biossíntese , Mutagênicos , Tiocianatos/farmacologia , Asas de Animais/anatomia & histologia , Actinas/biossíntese , Actinas/genética , Animais , Anticarcinógenos/toxicidade , Cruzamentos Genéticos , Sistema Enzimático do Citocromo P-450/genética , Família 6 do Citocromo P450 , Proteínas de Drosophila/genética , Drosophila melanogaster , Vetores Genéticos , Hipnóticos e Sedativos/toxicidade , Isotiocianatos , Larva/metabolismo , Testes de Mutagenicidade , NAD/metabolismo , Oligonucleotídeos/síntese química , Oligonucleotídeos/genética , Fenobarbital/toxicidade , Recombinação Genética/genética , Sulfóxidos , Tiocianatos/toxicidadeRESUMO
Escherichia coli C600 and C600(lambda) strains were tested for their susceptibility to the bactericidal action of 4% normal human serum. C600 survival was reduced to 30%, 23% and 16% after 60, 150 and 180 min of exposure to serum, respectively, whereas the percentage of survival of C600(lambda) was 199, 109 and 65% at the same times. The estimated exposition times for 50% killing showed an eight-fold difference, they were 23 and 202 min for C600 and C600(lambda), respectively. None of the two strains tested was killed when incubated with serum whose alternative complement pathway was inactivated by heating at 50 degrees C for 20 min, showing that this pathway, and not the classical one, was responsible of the bactericidal action, a conclusion further supported by the finding that both strains were differentially killed by the alternative complement pathway, C600 showing a 14X, 10X and 4X greater susceptibility than C600(lambda) at 60, 120 and 180 min of exposure to serum whose classical pathway was selectively inhibited by chelation with 10 mM EGTA plus 2 mM MgCl2. We feel that lambda phage may lower the serum sensitivity of its lysogen by altering the bacterial external surface, perhaps by the inclusion of some protein encoded by an accessory gene of the lambda genome, and thus interfering with either the formation, deposition or activity of the membrane attack complex.