FIGURE 5:

Heterogeneity of radial spokes in ndk5 axonemes. (A) Density map from the total 96 nm–based average shown as longitudinal sections. (B) A corresponding 3D variance map from aligned and normalized particles. Scale bar: 20 nm. The regions with high variance have darker pixel densities. An absence of variance and electron density in the spokehead and spokeneck indicates that the majority of spokes miss the bifurcated neck and head parts. High variance in the spoke stalks infers either orientation or compositional heterogeneity in that region. An absence of variance in individual MTDs serves as a positive control of applied analysis procedures. The representative density map subaveraged from subvolumes reveals typical straight, rigid conformation of spoke stalk with respect to the doublet in MTD 1 (C), in contrast to the subaverage from MTD 2 (D). Red dashed lines are drawn following the spoke-stalk density for the visual representation of the spoke tilt relative to the doublet. The subaverage from MTD 3 (E) shows complete absence of RS assembly. The numbering of the doublets is arbitrary and does not correspond to accepted numbering in the WT axoneme. Scale bar: 24 nm.