Fig. 4. Reduction of rhoptry cholesterol content and [NBD-C]-LDL acquisition by antisense-expressing parasites. Fibroblasts infected with Toxoplasma gondii, wild-type (A-A') or ROP2AS (B-B') were cultivated for 24 hours in medium containing 10% FCS, fixed, cytochemically stained with filipin for cholesterol detection and observed by fluorescence microscopy as described (Coppens et al., 2000). Twenty-four hours post-infection with T. gondii, wild type (C-C') or ROP2AS (D-D') in medium containing 10% LPDS, fibroblasts were pulse-labeled at 37°C with 0.1 mg/ml of [NBD-C]-LDL for 60 minutes. Cells were washed and processed for fluorescence observation.