![Figure 5. A model based on dynamic viscoelastic KT–MT bonds reproduces the dynamic behavior of middle sister KT pairs. (A) KT–pole (left KT, red; right KT, blue) and inter-KT (green) distances, and cohesin rest length (purple) over time. The periods of sister KT and inter-KT oscillations (by fast Fourier transform) are 280 s and ∼5 min and 150 s and ∼2.5 min, respectively (compare with Fig. 1 B). (B) Position of sister KTs (left KT in red, right KT in blue) and spindle poles (black) over time (the spindle equator is set to zero). (C and D) Inter- (C) and intra-KT (D) distances produced by the model (2.31 ± 0.24 µm [n = 400] and 0.12 ± 0.01 µm [n = 60], respectively) shown side-by-side with the distance observed experimentally in live (inter-KT distances; n = 558) or fixed (intra-KT distances; n = 228) cells. Experimental data are shown in dark blue and model data are shown in light blue. The inset in D shows a close-up of the distribution of the data produced by the model. (E–H) Time evolution of the total number of attached MTs (17 ± 4 and 44% in depolymerization state; E), attached Ndc80 complexes (49 ± 19; F), and mean (G) and maximal (H) intra-KT distance of the left (red) and right (blue) sister KTs. In H, the maximum intra-KT distances and the corresponding sister KT positions for the left (red) and right (blue) sister KTs are shown over time. The gray and pink shaded areas mark the AP movement of the sister attached to the right and left pole, respectively. The AP-moving sister generally displays a higher intra-KT distance. (I and J) Kinetic profiles of normalized P (J) and AP (I) movement for oscillating KTs. The solid lines through the kinetic data in I and J were obtained by fourth-degree polynomial fitting. The insets in I and J represent the normalized AP and P velocity kinetics obtained from the derivatives of the polynomial curves of AP and P movement, respectively. Note, the slight differences between the model and the experimental results (I and J vs. Fig. 1, E and F, insets) can be explained by the fact that the time of the P-AP switch can be tracked with high precision in the model, but not in the experiments. This would account for the delay in the normalized time for reaching maximal velocity for both the AP- and P-moving sister KTs in the model results. An example of a model simulation of KT and kMT dynamics for an oscillating middle KT pair is shown in Video 1 (top).](https://cdn.rupress.org/rup/content_public/journal/jcb/201/4/10.1083_jcb.201301022/6/jcb_201301022r_fig5.jpeg?Expires=1771587503&Signature=DVQiSfLEhQLPETTLYd~j4J1-ivwBr6uHohd63yTwKGf7RttyBDua7pMLvkx4ICj54gfZ9mGsFb3ysX28bURKpijwgfC1Ot~~DSj2tE5ktpK7GrMLPZRnoaWMipuY8Zibgr9sdsbn1-l76nNtt2WELG4XjCNU9eio1hCDXiBI4~AGO49w7yQsScjJMYAUkPbctmvFgMO6~ROHU2oz7NJQVarXC07NJpHeca4hB4Vocde7mDwVjTPFjju4Vq5nCM2wcbwXD5YR8MXhlI4dz0YFVU-9S6xCsVVlAQw7w4suCDS9g5lW9A5SeQ-yRO3SmJHEAj8DJaqvbG9HSD1vQu5J3g__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A model based on dynamic viscoelastic KT–MT bonds reproduces the dynamic behavior of middle sister KT pairs. (A) KT–pole (left KT, red; right KT, blue) and inter-KT (green) distances, and cohesin rest length (purple) over time. The periods of sister KT and inter-KT oscillations (by fast Fourier transform) are 280 s and ∼5 min and 150 s and ∼2.5 min, respectively (compare with Fig. 1 B). (B) Position of sister KTs (left KT in red, right KT in blue) and spindle poles (black) over time (the spindle equator is set to zero). (C and D) Inter- (C) and intra-KT (D) distances produced by the model (2.31 ± 0.24 µm [n = 400] and 0.12 ± 0.01 µm [n = 60], respectively) shown side-by-side with the distance observed experimentally in live (inter-KT distances; n = 558) or fixed (intra-KT distances; n = 228) cells. Experimental data are shown in dark blue and model data are shown in light blue. The inset in D shows a close-up of the distribution of the data produced by the model. (E–H) Time evolution of the total number of attached MTs (17 ± 4 and 44% in depolymerization state; E), attached Ndc80 complexes (49 ± 19; F), and mean (G) and maximal (H) intra-KT distance of the left (red) and right (blue) sister KTs. In H, the maximum intra-KT distances and the corresponding sister KT positions for the left (red) and right (blue) sister KTs are shown over time. The gray and pink shaded areas mark the AP movement of the sister attached to the right and left pole, respectively. The AP-moving sister generally displays a higher intra-KT distance. (I and J) Kinetic profiles of normalized P (J) and AP (I) movement for oscillating KTs. The solid lines through the kinetic data in I and J were obtained by fourth-degree polynomial fitting. The insets in I and J represent the normalized AP and P velocity kinetics obtained from the derivatives of the polynomial curves of AP and P movement, respectively. Note, the slight differences between the model and the experimental results (I and J vs. Fig. 1, E and F, insets) can be explained by the fact that the time of the P-AP switch can be tracked with high precision in the model, but not in the experiments. This would account for the delay in the normalized time for reaching maximal velocity for both the AP- and P-moving sister KTs in the model results. An example of a model simulation of KT and kMT dynamics for an oscillating middle KT pair is shown in Video 1 (top).
