Central pair microtubule defects in TbHydin RNA-induced cells. (A and B) Transmission electron microscopy images of TbHydin non-induced cells (A) and RNAi-induced cells 48 h after induction (B). Note the aberrant position of the central pair microtubules in (B) compared to the non-induced control. (C-E) Graphical representation of the central pair mispositioning in TbHydin RNAi-induced flagellar profiles (D and red bars in E) compared to the fixed central pair position seen in non-induced controls (C and black bars in E). (F) A cell late on in the cell cycle with two flagella. The new flagellum (NF) has a misoriented central pair while the old flagellum (OF) is normal. (G) Loss of the central pair microtubules in TbHydin RNA-induced cells. Flagellar profiles were analysed at 72 h after RNAi induction, and loss of one or both of the central pair microtubules quantified. Scale bars = 200 nm.