Dresden 2017 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 25: Posters - Cytoskeletal Filaments
BP 25.10: Poster
Dienstag, 21. März 2017, 14:00–16:00, P2-EG
The shape of k-fibers reveals the existence of torques at the spindle poles — •Maja Novak1,2, Bruno Polak2, Zvonimir Boban1, Iva M. Tolic2, and Nenad Pavin1 — 1Faculty of Science, University of Zagreb, Zagreb, Croatia — 2Rudjer Boskovic Institute, Zagreb, Croatia
During cell division, the mitotic spindle made of microtubules drives segregation of the genetic material into two nascent cells. Bundles of microtubules known as k-fibers pull on kinetochores, protein complexes on the chromosomes. Recently, by investigating bundles of microtubules at the outer part of the spindle, we have found that bridging microtubules, which link sister k-fibers, attain a C-shape and balance the forces at the kinetochores (Kajtez et al, Nat Commun 2016). However, it is unknown what forces and torques are present in the inner part of the spindle. To answer this question, we have developed a theoretical model, where sister k-fibers are represented as an elastic slender rod shaped by forces and torques generated at the spindle poles. We found that k-fibers attain a general helical shape, whose projection on a plane can be identified as C-, S- and M- shape. By live-cell imaging experiments, we observed these three characteristic shapes, indicating a helical shape of k-fibers and consequently torques in the direction of the major axis. In addition, we found that helical shapes can exist under both tension and compression. We conclude that torques, as well as forces at the spindle poles determine the shape of mitotic spindle.