FIG 6 .

Knockout experiments show that glucan synthase is not essential for tissue cyst formation by Toxoplasma in vitro. (A) PCR products for the HXGPRT gene in the glucan synthase locus are present in the glucan synthase knockout (ΔTgGS), but not in nontransformed Toxoplasma (wild type [WT]). Conversely, the Toxoplasma glucan synthase gene (TgGS) is present in nontransformed parasites, but not in the ΔTgGS parasites. (B) In vitro tissue cysts from nontransformed Toxoplasma are labeled with DBL (green walls), while nuclei are labeled with DAPI (blue). (C) ΔTgGS in vitro tissue cysts showlabeling of walls with DBL similar to that of nontransformed tissue cysts shown in panel B, (D) ΔTgGS bradyzoites within an in vitro tissue cyst are la beled with anti-SAG2Y antibody similarly to nontransformed bradyzoites.