Heatmap comparison of changes in gene expression after sulfur addition. Changes in transcript abundance are shown, on a log2-fold scale, for the TK genes listed. Comparisons were made of the cDNA libraries generated from RNA isolated before and 20 min after addition of sulfur to T. kodakarensis cells growing exponentially in pyruvate. Values were calculated based on changes in the abundance of cDNA reads, as described in Materials and Methods. The T. kodakarensis data are aligned and compared with the microarray hybridization results reported for sulfur-induced changes in transcription of the homologous mbx and mbh operons, and related homologous genes, in P. furiosus.