Distinct classes of developmentally regulated genes and tachyzoite transcript abundance levels. The tachyzoite cDNA/reference ratios are shown in the left column, represented on a scale of gray (below the median value for all contigs) to white (equal to the median value for all contigs) to blue (above the median value for all contigs). The mean bradyzoite/tachyzoite ratios for all time points are shown in the columns to the right, represented on a scale from green (induced) to red (repressed). Genes represented by singleton ESTs are not included in this cluster. Fold change values that were not statistically significant according to SAM are marked with an asterisk and were not used in clustering the genes into distinct classes. Classes are based on the bradyzoite/tachyzoite expression patterns. The number given for each gene is the Ctoxoqual contig number. Locations or functions (either known or predicted) of genes are given in parentheses. Gene abbreviations: SAG, surface antigen; PPD, pyridoxal phosphate dependent; LDH, lactate dehydrogenase; SRS, SAG1-related sequence; MAP, methionine aminopeptidase; BAG, bradyzoite antigen; ENO, enolase; DRPA, homologue of deoxyribose phosphate aldolase; MIC, microneme; ROP, rhoptry; G6PD, glucose-6-phosphate dehydrogenase; GRA, dense granule; NTPase, nucleoside triphosphate hydrolase.