Figure 2.
A,B. GFP-Utrophin (GFP-Utr; F-actin probe) and TMR-Kabiramide C (TMR-KabC; F-actin barbed end binding) fluorescent images of a Xenopus growth cone on PDL-laminin collected with a TIRF microscope. Note bright TMR-KabC fluorescence at the periphery (arrow in B), indicating a high concentration of F-actin barbed ends. C. Merged image of the growth cone in (A,B) shows strong co-localization of GFP-Utr and TMR-KabC in central domain, but primarily TMR-KabC in the peripheral domain. Weak labeling of peripheral actin with GFP-Utr is consistent with the slow association rate of GFP-Utr onto recently polymerized F-actin. D. Single line kymograph constructed from region indicated by the white line in (C). The slope of the diagonal bands of GFP-Utr and TMR-KabC fluorescence (arrows) indicates a retrograde flow rate of ~ 4 μm/min. Scale bars, 5 μm or as indicated. With permission from Santiago-Medina et al. (2012) Dev. Neurobiol. 72, 585-599.