Experiment design for global analysis of UV-response in Halobacterium NRC-1. Halobacterial cells were harvested from the growth medium, resuspended at a low density in a clear isotonic buffer, and placed on ice. Total RNA prepared from an aliquot of the cells at this point was used as the reference (R) in microarray analyses. Subsequently, one-half of the cell suspension was kept aside on ice for use as control. The remainder was irradiated on ice with UV-C light and post-irradiation the cells were diluted twofold in CM and allowed to recover at 42°C under light or dark conditions. Total RNA was prepared at 30 and 60 min from both the light and dark repair samples. The control was processed in a manner identical to the 60-min light repair sample, except that it was not irradiated.