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Doctoral Thesis
DOI
https://doi.org/10.11606/T.11.2019.tde-20191220-122659
Document
Author
Full name
Jose Pinto de Siqueira Junior
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1981
Supervisor
Title in Portuguese
Efeito da 8-metoxipsoraleina associada à luz ultravioleta longa em profagos e plasmídio de Staphylococcus aureus
Keywords in Portuguese
BACTÉRIAS PATOGÊNICAS
FUROCUMARINAS
LUZ ULTRAVIOLETA
PLASMÍDEOS
PROFAGOS
Abstract in Portuguese
O presente trabalho teve como objetivo avaliar a 8-metoxipsoraleina associada à luz ultravioleta longa (8MOP-UVL) na indução de profagos, na cura do profago responsável pela supressão da atividade lipolítica e na cura do plasmídio responsável pela resistência à tetraciclina, na linhagem 609tet-r de Staphylococcus aureus. As frequências de indução de profagos, após irradiação por UVL, na presença de 8MOP, quando lançadas em gráfico, em função da dose, revelaram uma curva de dose-efeito típica, de há muito conhecida para outros sistemas lisogênicos. Para as condições experimentais utilizadas, a frequência máxima de indução foi maior que aquela obtida após irradiação por luz ultravioleta curta (UVC). Após irradiação por UVL, na presença de 8MOP, a partir da linhagem lip- utilizada, variantes lip+ foram obtidas com frequências maiores que as obtidas espontaneamente, sendo o tratamento tão eficiente quanto a UVC. Fagotipagem e experimentos de conversão fágica evidenciaram a ocorrência de cura do profago, detectando-se assim mais um efeito biológico da associação 8MOP-UVL em bactérias. Após tratamento com 8MOP-UVL, variantes sensíveis à tetraciclina foram obtidas com frequências maiores que as obtidas espontaneamente ou sob ação de temperatura elevada ou brometo de etídio. Com as variantes sensíveis e com a linhagem original, foi feita eletroforese de DNA em gel de agarose e o resultado mostrou que concomitante ao desaparecimento do caráter fenotípico, houve também desaparecimento de uma banda que pôde ser identificada como relativa ao plasmídio portador do gene para resistência a tetraciclina. Assim a associação 8MOP-UVL poderia ser considerada como um novo agente capaz de eliminar plasmídios de S. aureus.
Title in English
Effect of 8-methoxypsoralen plus near ultraviolet light on prophages and plasmid of Staphylococcus aureus
Abstract in English
The present research was aimed to evaluate the association of 8-methoxypsoralen plus near ultraviolet light (8MOP-NUV) on induction of prophages and cure of the prophage responsible for suppression of the lypolitic activity on Staphylococcus aureus. The same association was also investigated on the cure of the plasmid responsible by tetracycline resistance on the used strain 609tet-r. The prophage induction frequencies after NUV irradiation associated to 8MOP treatment have shown in a graphic a typical dosis-effect curve also known for other lysogenic systems. For the experimental conditions the maximum frequency of induction was greater than that obtained after far ultraviolet light irradiation (FUV). After 8MOP-NUV treatment, variants lip+ were obtained from the lip- strain used, in frequencies which were greater than those achieved spontaneously. This treatment was as efficient as the FUV one. Bacteriophage typing and experiments of phage conversion have shown that cure of prophage was achieved. This can be considered one additional biological effect of 8MOP-NUV association. Following 8MOP-NUV treatment, variants which were tetracycline sensitive were obtained. The observed frequencies were higher than those achieved spontaneously or after ethidium bromide and high temperature treatments. Gel agarose electrophoresis were carried out from the original strain and non-resistant variants lysates. The results have shown that loss of resistance correspond to a loss of a band on agarose gel which must correspond to the plasmid carrying the tetracycline resistance gene. In this way 8MOP-NUV association can be considered as another agent able to eliminate plasmids from S. aureus.
 
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Publishing Date
2019-12-20
 
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