Figure 1.
Composite photomicrograph of a micronucleus in RTL-W1 cells directly after cytokinesis (arrow).
Nuclei and micronuclei were stained using Acridine Orange dye. The micrograph was captured at 1000× magnification and is a composite of bright-field and epifluorescence microscopy. Scale bar = 5 µm.
Table 1.
Corrected and uncorrected REPs relative to NQO, as well as respective corrected and uncorrected EC25 values in the micronucleus assay with RTL-W1 cells.
Figure 2.
Exemplary concentration-response curve (carbazole) measured in the micronucleus assay with RTL-W1 cells (closed circles).
The concentration-response curve for NQO (open circles) and the blanks, i.e. control cells without treatment (open square and lower dashed line), are given for reference. Induction factors are fold-changes relative to blanks. EC25 values relative to the maximum induction of NQO (upper dashed line) were calculated to derive fixed-effect-level-based REPs. Concentration values on the x-axis refer to nominal medium concentrations of the substances. Circles represent mean values measured in duplicate experiments, error bars the standard deviation. The red line depicts 25% of the maximum induction caused by the standard NQO. Asterisks denote statistically significant differences compared to blanks (one-way ANOVA with Dunnet’s test, p≤0.05).
Figure 3.
Uncorrected and corrected relative potency (REP) values of hetero-PAHs.
Uncorrected values refer to nominal concentrations and corrected to measured concentrations in the exposure medium after incubation without cells. N.d.: inactive in assay system, i.e. substances which did not reach the stipulated level of 25% induction of the NQO standard.
Figure 4.
Dose-response curves in the micronucleus assay with RTL-W1 cells for all investigated heterocyclic compounds (closed circles).
Standard curves for NQO (open circles) and blanks, i.e. control cells without treatment (open squares, grey line), are given for reference. Induction factors are fold-changes relative to blanks. Concentration values on the x-axis refer to nominal medium concentrations of the substances. Dots represent mean values measured in duplicate experiments, error bars the standard deviation. Asterisks denote statistically significant differences compared to blanks (one-way ANOVA with Dunnet’s test, p≤0.05).