Mutagenic pathway

Translesion Synthesis and Mutagenic Pathways in Escherichia coli Cells... 

Figure 15.3 Current model for insertion and extension of+BP and -BP adducts by Pols IV and V in the nonmutagenic and G —> T mutagenic pathway in E. coli (see text).

Mismatches. Watson-Crick A T or G C pairs have to compete with 8 non-Watson-Crick alternatives termed mispairs or mismatches. These are the purine-pyrimidine G T and A C pairings, the purine-purine GO, A A and G A and the pyrimidine-pyrimidine C C, T T and C T mismatches. Mutagenic pathways are divided into... 

Vanillin has been reported to be a bio antimutagen, demonstrating the abiUty to protect against mutagenic effects by enhancement of an error-free post-rephcation repair pathway. Vanillin has been reported to be nonmutagenic in bacterial systems, but conflicting results in mammalian systems leave no clear indication of the SCE-inducing potential of vanillin. 

On the other hand, chloral, a metabolite of trichloroethylene, which is also a mutagen and inducer of aneuploidy, is produced via a pathway which is more predominant in rats and humans than in mice (Kimbrough et al. 1985). A study using identical trichloroethylene concentrations in rats and mice, and which found increased aneuploidy in rats but no effect in mice, offered this mechanism as a possible explanation (Kligerman et al. 1994). An implication from this would be that humans are similarly more susceptible to chloral-mediated effects of trichloroethylene exposure. 

Current evidence favors a-hydroxylation as a major activation pathway for NPYR. The model compounds, 2-acetoxyNPYR and 4-(N-carbethoxy-N-nitrosamino)butanal are both highly mutagenic towards typhimurium without enzymatic activation (21, 22). 

Sunscreens and their degradation metabolites analyzed in this study are potential inducers of the oestrogen (ER) and aryl hydrocarbon receptors (AhR, also known as Dioxin Receptor). Ectopic activation of these pathways can cause severe damage to organisms and their ecosystem by altering reproduction, hormonal and/or circulatory systems [73-75] as well as they have been associated with carcinogenic and mutagenic effects [76-78]. 

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