Figure 3.

Simplified mechanical models of the axoneme. Selected longitudinal members (outer doublets) experience distributed axial loads and bending moments due to dynein activity. Colour indicates axial stress. (a,b) 3D model with six outer doublets. (a) Steady, uniform dynein force applied between doublets on one side (e.g. P) of the axoneme produces bending in one direction and a small amount of twist. (b) Steady dynein loading applied between doublet pairs equally on both P and R sides of the axoneme leads to a straight, slightly twisted configuration, with axial stress in doublets. (c) A 2D model showing steady, distributed axial loads and axial stress, in response to steady dynein activity on a single (P or R) side. (d) Axial stress in a 2D model assuming equal activity on both P and R sides. (Online version in colour.)