Fig. 6. Phenotype of cells overexpressing SodA. (A) Exponentially growing cells (Ax2, control cells expressing ß-galactosidase and SOD-OE cells, the latter two grown in 50 µg/ml G418) were diluted to a density of 3x10⁵/ml in fresh HL5 medium in triplicate. The cultures were incubated at 22°C and 180 rpm and aliquots were taken in duplicate every day to determine cell density. One experiment typical of three independent experiments is shown. (B) Control cells (expressing ß-gal from the actin 15 promoter) grown in 100 µg/ml G418 and SOD-OE cells grown in 20 and 50 µg/ml G418 were harvested, washed in phosphate buffer and plated on phosphate-buffered agar at the cell densities indicated. The plates were incubated at 22°C in the dark and photographs were taken after 12 hours. No aggregates subsequently formed on the two plates of SOD-OE 50 cells at the two lowest cell densities and no aggregates were seen at any of these cell densities for SOD-OE cells grown in 100 µg/ml G418 (data not shown).