Strains and Growth Conditions
Chlamydomonas sp. UWO241 and Chlamydomonas reinhardtii(cc-1690) were grown axenically in Bold’s Basal Medium (BBM) supplemented with 10 mM NaCl. All cultures were aerated continuously with ambient air filtered by a 0.2 µm filter in 250 ml glass growth tubes suspended in thermo-regulated aquaria. A continuous growth irradiance of 130 µmol photons m-2s-1 was generated by fluorescent tubes (Sylvania CW-40) and measured with a quantum sensor attached to a radiometer (Model LI-189; Li-Cor). Algal cultures were exposed to heat stress by transfer to aquaria maintained at 24°C (UWO241) and 42°C (C. reinhardtii ). Mid-log cultures were used in all experiments.