FIG 4.

Effects of 75 nM SQ109 on T. cruzi trypomastigotes, as observed by scanning electron microscopy. (A) Untreated trypomastigotes exhibit a (typical) elongated shape and have a smooth cell surface. (B to D) Trypomastigotes treated with SQ109 for 6 h (B) and 12 h (C and D) show torsion of the cell body, the appearance of a large number of vesicles associated with the plasma membrane (arrows), and wrinkling of the parasite's surface. Scale bars = 2.5 μm. The observation of deranged morphologies at 6 to 12 h suggests that the depletion of sterols (which requires multiple cell divisions, and these cells are not dividing) is not involved.