Microarray analyses were performed to compare the gene expression profiles of wild-type and several mutant strains of the ciliated protozoan Tetrahymena thermophila. Elimination of H3K4 methylation (hht2-K4Q) and knockout of either of the ubiquitylation enzymes (delta-UBC2 and delta-BRE1) affects a broader spectrum of genes than elimination of H2B ubiquitylation (htb1-K115R). Cells at mid-logarithmic growing phase (cell density of 200,000 cells/ml) were collected. Then total RNAs were extracted and hybridized.