Global transcriptome analysis indicates that depletion of rps13 and ribosomes leads to cell cycle arrest in G1

Affymetrix Toxoplasma microarray data was analyzed to determine whether there was an association with a G1 transcript profile. Four hundred seventy-five genes with significant gene expression differences (Welch T-test, P = 0.01) between ±ATc samples were identified. Genes were clustered into those increased (153) or decreased (322) -ATc. There are a number of genes with diminished expression and pronounced over expression -ATc including LDH1, 4 zinc finger proteins, leucine-rich protein, and ABC transporter-like molecules, myosin-related molecules with many fold increases and one AP2 protein with a small increase. These gene sets have a large overlap with G1 genes defined in an ongoing cell cycle expression study in T. gondii (Behnke, White). Over 60% of those genes that have diminished expression -ATc overlap with genes that are diminished at G1, and over 40% of genes with increased expression -ATc overlap with genes that are up regulated at G1. A hypergeometric distribution of this association suggests that the probability of this happening by chance is essentially zero. Thus, by both methods, FACS and arrays, parasites -ATc display a G1 profile. To determine the global transcriptional differences of the RSP13 conditional mutant with and without anhydrotetracycline (ATc). Four replicates each.