FIGURE 6.

The overexpression of TopA allows cell survival in the presence of seconeolitsine. Exponentially growing cultures of R6 carrying pLS1R (open symbols) or pLS1R-topA (full symbols) were grown in AGCH containing 0.8% sucrose to A₆₂₀ = 0.6. At this moment, the cultures were diluted 20-fold in medium containing 0.4% sucrose and 0.4% maltose. Growth (A) and viability (B) in the absence or the presence of compound 17 (seconeolitsine) at different concentrations were determined. Initial A₆₂₀ values were 0.17 for pLS1R and 0.15 for pLS1R-topA. Initial viable values were 6.6 × 10⁷ colony-forming units/ml for pLS1R and 3.2 × 10⁷ colony-forming units/ml for pLS1R-topA.