mRNA half-life in relation to transcript abundance, operon size (in number of genes) and transcript length (in nucleotides) in S. solfataricus. (a) Scatter plot of transcript abundance versus half-life. mRNA half-lives are shown in log2-scale. Transcript abundance represents log2-transformed expression (cDNA/genomic DNA) ratios, normalized such that the average of the log ratios equals zero. Red and blue dots represent genes for ribosomal proteins and polymerase subunits, respectively. (b) Box plots of half-life distributions for transcripts in one-, two- and three-gene runs; 50% of the genes are included in the boxes, and 80% between the whiskers; the line within the box represents the median half-life. (c) Scatter plot of mRNA half-life versus transcript length (counting from first start to last stop codon in each run). Genes belonging to one-, two- and three-gene runs are shown in grey, red and blue, respectively.