Abstract
Transcriptionally active regions of the Haloferax volcanii genome were mapped by hybridization of radiolabeled cDNA to Southern blots of our minimal set of overlapping cosmid clones covering 96% of the 4.1-Mbp genome. Transcription during exponential growth occurred in nearly every region of the 2,920-kbp chromosome. Large parts of the 690- and the 86-kbp plasmids were transcribed, but the 440-kbp plasmid showed little expression. Transcription after a 40-min heat shock at 65 degrees C was generally reduced, apart from a small set of strongly expressed loci all situated on the chromosome.