T. gondii genes, probes, and probe-level expression profiles. Top panel shows a 50 kb region of chromosome Ib, illustrating, in addition to the 3'-biased expression profiling probes that are available genome-wide, the high density of probes available for this chromosome, including intron, exon, and antisense probes for each annotated gene (blue genes run from left to right; red from right to left). Transcript discovery probes interrogate unannotated EST clusters (≥3 ESTs) and ORFs (≥150 nt) that intersect with BLAST hits (bitscore ≥100). A barplot provides normalized probe-level expression data (union of sense probe intensities from antisense target kits, antisense probe intensities from sense kit), indicating probable expression of unannotated EST clusters and BLAST hits. See text and Table 1 for further details. Bottom panel displays a 6 kb span at higher resolution, illustrating the validation of gene structure, and comparable transcription levels in upstream ESTs that may correspond to non-coding exons.