Tendrillar extensions of TbMORN1. (A and B) YFP-TbMORN1 (arrowheads) is sometimes seen to exhibit tendrillar extensions (arrows) to its normal hook-shaped pattern. YFP::TbMORN1 cells were fixed with paraformaldehyde, permeabilized with detergent, and labeled with anti-GFP antibodies. (C and D) The YFP-TbMORN1 tendrils (arrows) contact the basal body and maturing probasal body. Flagella extracted from YFP::TbMORN1 cells were labeled with anti-GFP antibodies and the YL1/2 antibody. YL1/2 labels fibers emanating from the mature basal body. The probasal body and the basal body are both labeled (arrowheads), indicating that the probasal body has matured. (E) Gallery showing various morphological forms of the YFP-TbMORN1 tendrils. Variously, these are single thin tendrils (i), single thick tendrils (ii), coat-hanger shapes (iii and iv), and figure-eight structures (v). All images show isolated flagella from YFP::TbMORN1 cells, fixed with paraformaldehyde. (F) A tendril emanating from the probasal body is occasionally seen in EM images of isolated flagella. The MTQ, originating between the basal body (black arrowhead) and the probasal body (white arrowhead), is indicated. The FAZf is marked for orientation. (G) Both YFP-TbMORN1 and TbLRRP1 can be found on the tendril and as part of the MTQ. Isolated flagella from YFP::TbMORN1 cells were labeled with anti-GFP (20-nm gold particles) and anti-TbLRRP1 (10-nm gold particles). Only half of the MTQ (bar) appears to be labeled. (H) The YFP-TbMORN1 tendril (long arrow) does not appear to contain alpha-tubulin (short arrow). The probasal body (arrowhead) is indicated in the DIC overlay. Isolated flagella were fixed with paraformaldehyde and labeled with anti-GFP and anti-alpha-tubulin antibodies. All immunofluorescence images are maximum-intensity z projections. Bars, 1 μm (A to E and H) and 500 nm (F and G).