大肠杆菌SOS反应诱导动力学和诱导抑制作用的研究

STUDIES ON THE KINETICS AND INHIBITION OF SOS INDUCTION IN E.COLI.

在E.Coli K12带有融合基因Sfi:Lacz的PQ37菌株上,用改良的SOS显色试验程序,研究了化学诱变剂(4NQO和MMC)诱导的SOS反应诱导动力学和化学物质(肉桂醛和二烯丙三硫)对SOS反应的抑制作用。发现用脉冲式诱导的程序,可使4NQO诱导Sfi基因的SOS反应在15分钟内出现,30～60分钟时其峰值比持续诱导高一倍,但 MMC诱导的并不完全相同,表明SOS反应诱导动力学的类型随诱变剂不同而有所不同,改良的脉冲式诱导程序能更如实地揭示诱导效应。与此同时,本研究还证明了肉桂醛和二烯丙三硫对4NQO脉冲诱导的SOS反应的抑制效应(P<0.01),其作用环节可能是在菌体内破坏4NQO或干扰它的代谢活化。

Studies on the kinetics of SOS responses induced by 4NQO and MMC, and the inhibition of SOS by cinnamaldehyde and diallyl trisulfide witth the modified protocol of SOS Chromotest in the sfi : lacz fusion strain PQ37 of E.coli K12 were conducted.The SOS responses of the gene sfi was derived by the modified pulse-induction in 15 minutes by 4NQO; however, the height of the responding peak by 30-60 minutes continueous induction reached two folds as that of the former.But there was inconsistency between the kinetics of SOS induction by MMC and. that by 4NQO. Results suggested that the pattern of SOS inducing kinetics vary with the mutagens, and the inducibility of SOS response could be better showed by the modified pulse induction protocol.It was demonstrated that cinnamaldehyde and diallyl trisulfide rendered suppression on the SOS response induced by 4NQO impulsively.It is suggested that the suppressors could interfere the metabolic activation of 4NQO or breaking down 4NQO within the cells.