Date of Award

Spring 5-15-2022

Degree Type


Degree Name

Doctor of Philosophy (PhD)




Ross, Jennifer L.


Asters, LLPS, MAP65, Microtubule, Tactoids

Subject Categories

Biochemistry, Biophysics, and Structural Biology | Biophysics | Life Sciences


One of the most fascinating micron-scale structures in the biological world is the cell cytoskele- ton, with numerous components of different sizes, shapes, and geometries working together. How the local interactions of these macromolecules and polymers in nano-scale help self- organize into this higher-order micron-scale structure remains an open question in the field of biophysics. In this thesis, via a minimal two-protein in vitro system containing cytoskeletal fiber microtubule and associated protein MAP65, I try to address self-organization through passive entropic force mechanisms. I use techniques like protein purification, light microscopy, and image analysis to quantify my results. First, I show how crowded environments contribute to microtubule nucleation, polymerization, and bundling via experiments and simulations. Next, I discuss a self-assembled limited-size microtubule bundle that is reminiscent of the mitotic spindle. I characterize these 'tactoids' and show that these are homogeneous and jammed inside. Lastly, I present results of the MAP65 condensate formation via liquid-liquid phase separation and quantification of their properties. Additionally, I elucidate a mechanism of non-centrosomal microtubule nucleation that may play an essential role in the mitotic spindle.


Open Access

Included in

Biophysics Commons