FIGURE 7.

NcGrx1 deficiency caused growth-inhibition, excessive ROS accumulation and apoptosis induction of parasites under oxidative stress. (A) ΔNcGrx1, NcGrx1 OE, and WT parasites were grown under oxidative stress (H₂O₂) in HFF. The proliferation of all strains was observed by IFA. Anti-SRS2 was used as a parasite surface marker. In each assay, 100 total PVs of each strain were counted. (B) Hydroxyl radical levels of parasites under normal condition or 100 μM H₂O₂ condition were determined by FACS analysis. The mean fluorescence intensity can reflect the hydroxyl radical level in parasites. (C) Apoptosis of ΔNcGrx1, NcGrx1 OE, and Nc1 parasites was assessed by the TUNEL assay after treatment with H₂O₂. The TUNEL-positive and TUNEL-negative parasites are shown in the left panel. The ratio of apoptotic parasites was counted using Graph Pad Prism (right panel). Asterisks indicate statistically significant results as determined by the t-test (p < 0.001). Scale bar = 5 μm. Asterisks indicated statistically significant results (***p < 0.001, **p < 0.01, and *p < 0.05 as determined by t-test). (D) The parasites were grown under normal condition or 100 μM H₂O₂ condition1. 1 × 10⁷ ΔNcGrx1, NcGrx1 OE, and Nc1 parasites were harvested. The concentration of GSH and GSSG was quantified by GSH and GSSG Assay Kit. The GSH/GSSG ratio was calculated and represented by a bar charts according to three independent experiments. Asterisks indicate statistically significant results as determined by the t-test.