Quantitation of luciferase activity in transformants expressing the luciferase gene. Luciferase activity was assayed using a luminescence counter. The bars represent the mean of three independent experiments. The standard deviation is indicated. (A) Luciferase activity of pPsaD-GLuc-derived transformants (T-PL...) is compared to wild type strains; T-PL-transformants descend from the wild type strain SAG 12.85. (B) Luciferase activity of pPsaD-GLuc-derived transformants (T-PLx...) is compared to wild type strains; T-PLx-transformants descend from a different wild type strain, CCAP 32/14. (C) Induction of luciferase activity in heat-shocked versus non-heat-shocked transformants. In pPsaD-GLuc-derived transformants (T-PL...) the luciferase gene is driven by the psaD promoter. In pHsp70A-GLuc-derived transformants (T-HL...) the luciferase gene is under control of the hsp70A heat shock promoter. Transformants were subject to a temperature shift from 23 to 36°C for 1 h. After a 1 h recovery phase at 23°C, cells were lysed and luciferase activity was assayed. As a reference, non-heat-shocked transformants were analyzed in the same way.