Dynein Resides along the Lateral Sides of Microtubules in Addition to the Plus Ends

(A) and (C) image and the corresponding intensity profile of dynein (green) and tubulin (red) for a cell in meiotic prophase. (B) and (D) image and the corresponding intensity profile of tubulin (red) for an interphase cell of the same strain as in (A). The two cells shown in (A) and (B) were in the same field of view, 9 ��m apart. (C) and (D) The intensities were measured along the white dashed lines shown in (A) and (B), respectively. The cytoplasmic tubulin signal was estimated as a difference between the cytoplasmic level (dashed red line) and the background level (red arrows). In the interphase cell, the signal of a single microtubule (horizontal solid red line), which is found in the part of the bundle near the cell tip, was ��50% above the cytoplasmic signal (D). The signal along the leading microtubules in the meiotic cell (horizontal solid red line) was ��100% above the cytoplasmic signal (C), indicating that there are two leading microtubules in the meiotic cell. The dynein signal (solid green line) shows several peaks along the leading microtubules, above the cytoplasmic level of dynein (dashed green line). This suggests that dynein is present along the microtubules and not only at their ends. (E) A time-lapse sequence of a cell expressing Mal3-GFP (plus end marker) during the SPB movement showing microtubule nucleation events (arrowheads). Nucleation events were identified when the signal was visible also in the previous and the subsequent image. The nucleation rate was 3.5 �� 1.2 min?1 (mean �� standard deviation, n = 105 events in three cells). Asterisks (A and C) indicate the position of the SPB. Vertical scale bars (A,B,E) represent 2 ��m.