Fig. 2.

Histones upstream of bradyzoite-specific genes become acetylated during stress-induced differentiation in vitro. Chromatin immunoprecipitation using anti-acetylated histone H3 (AcH3) or H4 (AcH4) was performed on Toxoplasma tachyzoites (Tz) or a population enriched in bradyzoites (Bz) due to alkaline pH exposure for three days. Upstream regions of constitutively expressed genes like tubulin (TUB) are acetylated regardless of life cycle stage. However, those of Bz-specific genes (LDH2) become hyperacetylated after subjecting parasites to a pH stress that induces cyst development. “No Ab” refers to a no antibody control ChIP and “input” is the PCR of the DNA prior to immunoprecipitation. Methods used have been described previously (Saksouk et al. 2005).