Description:

Professor Daniel Needleman: Harvard University

Title: Biophysics of Spindle Positioning and Elongation

Abstract: The spindle is positioned asymmetrically during the first mitotic division in C. elegans. We are investigating how different forces coordinated to move the spindle, and if these forces are generated from interactions with the cytoplasm, the cortex, or a combination of both. For this purpose, we constructed a laser ablation system capable of cutting complex patterns with high spatial and temporal precision, and we are applying it to quantitatively perturb spindle movements. We are also using fluorescent nanodiamonds to track cytoplasmic fluid flow as the spindle moves. We interpret our data using a combination of theory and simulations (in collaboration with Mike Shelley, NYU/Courant/Flatironan and Ehssan Nazockdast, UNC). Our results argue that pulling forces from the cortex drive key aspects of spindle motions, including the initial centering, subsequent asymmetric positioning, transverse oscillating behaviors, and elongation. We hope to provide a quantitative, integrated understanding of spindle positioning.

Host: Michelle Driscoll