Objective: To investigate the mechanism of acrylamide (AA)-induced mutational spectra in the tk gene of mouse lymphoma cells.
Methods: L5178Y3.2.7c-tk(+/-) cells were treated with AA at different concentrations. Mutational spectra of tk locus were analyzed by the mouse lymphoma assay (microtiter procedure), and frequency of loss of heterozygosity (LOH) analysis with allele special PCR. Subsequently determined the DNA sequence of negative LOH's colonies induced by AA.
Results: The LOH of mutants derived from AA induction was 78.8%, and showed a good dose-response relationship in large colonies. The occurrence of LOH of large colonies at lower doses (150 microg/ml and 300 microg/ml) were 25.0% and 33.3% respectively which were significantly different from those of control (66.7%), and at higher doses (600 microg/ml and 750 microg/ml) were 77.8% and 85.7%. By Sequence analysis showed that AA-induced point mutations were mainly base substitutions, and most of them were T:G-->G:T transversions.
Conclusion: Functional tk allele gene loss is major mutational event in both spontaneous and induced tk mutants. And point mutations were base substitution.