Figure 5

Msps depletion results in stable interphase microtubules. (A) Microtubule organisation after addition of colchicine, a microtubule destabilising drug. Control and Msps-depleted cells (5 days after dsRNA addition) were observed after 16 h incubation with colchicine. Some interphase microtubules remained in Msps-depleted cells, while nearly all microtubules were depolymerised in control cells. (B) Frequencies of cells that have residual microtubules after colchicine treatment. Lines indicate standard deviations from three independent experiments. (C) FRAP of GFP -tubulin. Small areas (arrowheads) of cells expressing GFP-tubulin were bleached and the recovery of fluorescence monitored for 5 min. Cells were treated with dsRNA for 5 days before the photobleach. (D) Percentages of the fluorescent recovery 5 min after photobleaching. Lines indicate standard deviations. Decreased turnover of tubulin dimers into microtubules was observed in Msps-depleted cells, indicating decreased microtubule dynamics. The estimated maximum recovery and t_1/2 are 74±5% and 54±6 s in control, and 39±9% and 63±18 s in Msps RNAi.