Fig. 2. Effects of imposed bending on the reversal of microtubule sliding in elastase-treated quiescent flagellar axonemes severed distally to the basal P-bend. (A,B) Video images with explanatory diagrams. UV flashes induced splitting of the flagellum into two doublet bundles. When the region of overlap was bent in the P-bend direction (left panels), the subsequent UV flashes induced backward sliding of the thinner bundle (open arrow in 5) in the whole region of the bending, whereas by imposed bending in the R-bend direction (right panels), forward sliding (filled arrows in 5) was induced. (C) Relative frequency of sliding patterns induced by imposed bending. (D) Tracings showing that, by bending the distal region of the flagellum in the P-bend direction, backward sliding in the proximal region of the bending (open arrow) and splitting of the distal edge of the thinner bundle in the bent region were induced by a UV flash. (E) Tracings taken from the same axoneme as shown in B (left) after bending.