The Dynamics of Dynein Distributions

(A) A time-lapse sequence of a cell expressing Dhc1p-3GFP (dynein, green) and mCherry-alpha2-tubulin (red) during one oscillation period. Dynein signal is stronger on the leading than on the trailing microtubules. Time points in minutes corresponding to the intensity profiles in (D) are marked below the image sequence. (B) Time-lapse images of a region in the cell, showing that dynein is distributed in a spotted pattern along the leading microtubules. The spots are stationary with respect to the cell cortex (arrowheads). Lower panels show GFP and mCherry channels separately. (C) Time-lapse images of a region in the cell, showing that when leading microtubules detach from the cortex, dynein also detaches from the cortex and remain on the plus ends of the depolymerizing microtubules (arrowheads). Lower panels show GFP and mCherry channels separately. (D) Dynein intensity in the cell from (A) is shown for the three time points marked below (A). The intensities were calculated as maximum projection along the short axis of the image showing the sum-intensity z-projection of the GFP (dynein) channel, thus the x-axis represents the long axis of the cell. The signal of the stationary dynein spot (arrowhead) increases as the SPB (asterisk) approaches it (compare the red and the green curve). The dynein spot is removed from the cortex when the SPB passes over its location (compare the blue curve with the previous two). The arrow shows the movement of the SPB. (E) Kymograph of the GFP channel showing that dynein, which is stationary with respect to the cell cortex (yellow horizontal bars), occasionally detaches (arrowheads) and moves towards the SPB (red trace coming from a strong GFP signal). The white horizontal scale bar represents 2 min. Asterisks in all panels indicate the position of the SPB and the vertical scale bars represent 2 ��m.