Figure 3.

Principal component analysis of the genes distinctly differentially expressed between smoke and KAR₁ treatments. Biplot representation of the principal component analysis. The figure shows the 199 genes at 1.5 h, 3 h, 6 h, 9 h, 12 h and 24 h that were distinctly differentially expressed (fold-change ≥ 4 and a corrected p-value < 0.1) in at least one experiment. All of the genes were plotted with respect to the first and second principal components and they are represented with a light gray text. The originally observed variables are plotted as red (smoke- related) and blue (KAR₁-related) responsive arrows. The arrows represent the association of the measured variables (fold-change) with the samples in the visualization: the length and location are proportional to the variable loadings on the two first principal components. The analysis suggests that much of the variability and difference between the two gene sets can be attributed to the two different treatments (smoke and KAR₁). Also see Additional File 10.