Fig. 8. A distinct ultrastructural defect accompanies TbCLH-depletion in procyclic culture form (PCF) trypanosomes. Electron micrographs of PCF cells following 48 h induction of clathrin dsRNA. (A) Two cells exhibiting normal (bottom) and abnormal (top) phenotypes. The major effects of clathrin double-stranded RNA expression is in the accumulation of vesicular profiles of variable diameter (∼50–400 nm) and a rounding up of the cell. Other structures (nucleus, mitochondria, acidocalcisomes) appear normal. (B) A more extreme example of a PCF clathrin RNAi cell. The plasma membrane has become smooth, possibly due to increased cytoplasmic pressure. In addition, the nucleus, kinetoplast and mitochondria appear normal. (C and D) Details of the Golgi region of PCF RNAi cells showing distortions to the trans-Golgi cisternae and membranes. The cell in (C) is in early mitosis, as the Golgi stack appears to be undergoing binary fission (Field et al., 2000). A, acidocalcisomes; K, kinetoplast; FP, flagellar pocket; M, mitochondria; N, nucleus; *, vesicles containing electron-dense matrix-like material (possibly FP-derived); arrowhead, distorted trans-Golgi. Scale bars: (A and B) 500 nm, (C) 200 nm and (D) 250 nm.