Analysis of the phenotype and the restriction enzyme mapping level of mutations induced by the new mutagen glycidyl methacrylate.
Glycidyl methacrylate (GMA) is a recently recognized chemical mutagen. In order to explore the mutagenicity and mutagenic process of GMA, plasmid pBR322 was used for in vitro binding, mutant screening, and restriction enzyme mapping. The binding between GMA and DNA in vitro has been verified by means of a spectrophotometric method. When pBR322 and GMA-bound pBR322 were used to transform Escherichia coli HB101, the following results were obtained: (1) The transformation efficiency of GMA-bound pBR322 was much lower than that of pBR322 alone. (2) GMA-bound pBR322 induced phenotype changes in competent cells (i.e., tetracycline-resistance inactivation or ampicillin-resistance inactivation). There were two mutants of pBR322, ApRTCS and ApSTcR, in the transformants and a deductive mutant ApsTcs in the nontransformants. (3) All of the selected mutants were stable and heritable. (4) When restriction enzyme maps were used to analyze the mutant ApRTcS, four of seven maps were changed, some sites were shifted to other resistant gene regions, for example, sites of Bg/I, EcoRI, HindIII, HincII, etc., and there was a new recognition site for HincII (252). We did not observe any DNA fragment insertion or deletion on any maps. Our results suggest that when GMA is covalently linked to the plasmid DNA, it gives rise to a premutagenic lesion of DNA that is converted in vivo into a point mutation.
Xie
D Y
DY
Institute of Occupational Medicine, Chinese Academy of Preventive Medicine, Beijing.
Gao
H L
HL
Zuo
J
J
Zhang
W
W
Li
Z S
ZS
Yang
H F
HF
Fang
F D
FD
D000668:Ampicillin Resistance / Q000235:genetics; D004269:DNA, Bacterial / Q000187:drug effects*; D004852:Epoxy Compounds / Q000633:toxicity*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D008689:Methacrylates / Q000633:toxicity*; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation; D010641:Phenotype; D011815:R Factors / Q000235:genetics*; D015183:Restriction Mapping; D013753:Tetracycline Resistance / Q000235:genetics; D014170:Transformation, Genetic / Q000235:genetics
D004269:DNA, Bacterial; D004852:Epoxy Compounds; D008689:Methacrylates; D009153:Mutagens; C007870:glycidyl methacrylate