UNC-6 stably polarizes UNC-40/F-actin oscillatory clustering. Anterior is left; ventral is down. (A) The time series shows F-actin polarity (orange arrowhead, grayscale) stabilized in the AC of an unc-6 mutant toward UNC-6 (zmp-5 > unc-6::nlg-1 TM::GFP; magenta), which is localized to dorsal uterine cell membranes (outlined with yellow lines; the asterisk marks a dorsal cell expressing UNC-6; the location of basement membrane [BM] is indicated with an orange line). (B) The red line in the graph represents the volume of the dominant F-actin patch in the time series shown above (the light green line is a small, transient F-actin patch localized away from the dominant patch). (C) Similar stabilization in four other cases. (D) The time series shows dynamic reorientation of F-actin polarity (grayscale) toward a changing UNC-6 source (magenta in top panels; outlined by broken lines in the bottom panels with spectral representation of fluorescence intensity). When the AC made contact with a new anterior source of UNC-6 (orange arrowheads), a polarized response was directed toward this new source, and polarity was lost on the posterior dorsal uterine cell as UNC-6 levels diminished (fading white arrowheads). See also Video 4. (E) A kymograph of the two outlined areas in the top of D from time 24 to 55 min of Video 4. (F) Quantification of UNC-6 (top) within the anterior domain and the associated increase in F-actin volume (bottom) during polarity reorientation after contact with this UNC-6 source (white boxed area in D). Bars: (A and D) 5 µm; (E) 0.5 µm.