Figure 8.

Comparison of the expression ratios of Arabidopsis genes detected by 70-mer oligonucleotides at different printing concentrations. Six Arabidopsis control cRNAs were spiked at varying levels corresponding to twofold differences into two labeling reactions containing rat brain and heart RNA. Another four Arabidopsis control cRNAs were spiked at a 1:1 ratio and served as normalization controls. The measured log₂ expression ratios from four independent experiments were plotted as the mean ± SD. The expected twofold change was detectable for all oligonucleotides at the different printing concentrations (twofold difference equals a log₂ratio of 1 or -1).