Table 1. Influence of ectopic A-lattice seams on MT dynamics.
| Growth (mean±s.e.m. (n) nm s−1) | Shrinkage (mean±s.e.m. (n) nm s−1) | Catastrophe (frequency±CL (n) min−1) | Growth % | Shrinkage % | Dithering % | |
|---|---|---|---|---|---|---|
| Plus end | ||||||
| B-lattice | 5.86±0.19 (85) | 158.5±6.0 (77) | 0.25±0.20/0.29 (135) | 92.1 | 1.9 | 6.0 |
| A-lattice (5 μM Mal3FL seed) | 6.22±0.15 (158) | 156.5±4.48 (124) | 0.33±0.29/0.38 (243) | 90.5 | 2.4 | 7.1 |
| A-lattice (50 μM Mal3FL seed) | 5.27±0.38 (27) | 139.3±10.7 (15) | 0.35±0.27/0.46 (54) | 74.7 | 1.8 | 23.5 |
| Minus end | ||||||
| B-lattice | 3.62±0.16 (25) | 90.9±10.8 (7) | 0.040±0.03/0.07 (25) | 99.2 | 0.6 | 0.2 |
| A-lattice (5 μM Mal3FL seed) | 4.11±0.11 (57) | 140.6±10.2 (23) | 0.080±0.06/0.10 (54) | 97.4 | 1.1 | 1.5 |
| A-lattice (50 μM Mal3FL seed) | 3.55±0.33 (10) | 130±20.1 (6) | 0.12±0.07/0.19 (19) | 98.3 | 1.7 | 0.0 |
MT dynamics parameters were determined from plots of MT length against time automatically generated from kymographs of dynamic (GTP/GDP) MTs (Fig. 2). Mean rates of growth and shrinkage were compared by one-way ANOVA and Tukey post test. The means of plus end growth rates (F (2, 267)=3.40, P=0.035), minus-end growth rates (F (2, 89)=3.82, P=0.026) and minus-end shrinkage rates (F (2, 29)=3.605, P=0.04) were significantly different, whilst plus end MT shrinkage rates were not (F (2, 213)=0.93, P=0.40). Using Tukey post test for pair-wise comparisons the differences in mean growth were significant (at P<0.05) between the two A-lattice seeds (5 μM Mal3FL was 1.2 × faster growth than 50 μM), but not between the A-lattice and B-lattice single-seam seeds. Minus-end shrinkage with A-lattice 5 μM Mal3FL seeds was significantly faster than from the B-lattice seeds. The Tukey test found no pair-wise significant differences in the minus-end growth rates at P<0.05. Total observation times were 598.4, 811.4 and 203.7 min at the plus end and 566.7, 703.8 and 158.5 min at the minus ends for B-lattice single-seam and A-lattice-enriched assembled from 5 and 50 μM Mal3FL seeds respectively. CL, Poison confidence limits, P=0.05.