Modeling a two-branch pipe lattice.

*See Figure 1B for lattice arrangement. Valve settings are denoted by s. Mutant status is indicated by S (spt3Δ) and D (taf1-2) [9]. Error is defined as the maximum absolute value of the error obtained between the measured [9] and calculated i0 values. Measured i0 for WT (experiment 3) corresponds to the average transcription frequency (mRNA/hr) using the data of Holstege [26] for the indicated clusters of genes (3, 4, 5, 6, 8, and 9) defined in Huisinga et al. [8]. Measured i0 for experiments 0–2 is the result of the following calculation: Transcription frequencies from experiment 3 (WT), for individual clusters, were multiplied by the fold changes in transcription (linear scale) measured previously with mutants spt3Δ and taf1-2 by Huisinga et al. [9]. “C∶E–1” error is defined in the text.