Current Research

Superimposed confocal planes of budding yeast cells expressing surface (GFP-Gpa1) and spindle pole body (CFP-spc42) reporters. Scale bar is 10 μm.
Role of forces and of micromechanics of biopolymers in the cellular process of cell division. To carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex non-equilibrium processes with high fidelity, in an environment dominated by thermal noise. We use quantitative image analysis algorithms applied to populations of cells expressing up to three different fluorescent markers (spindle pole components, cell surface components, and chromosome components) to determine the precise motions arising from forces involved in chromosome segregation. We investigate how different force generators on the mitotic spindle impact fluctuations and the important transitions in spindle length during mitosis.
Cartoon of molecular motors on F-actin and microtubule filaments.
Mechanical properties of the cytoskeleton. The cytoskeleton is a network of polymers that can span the cell volume. It gives the cell its mechanical strength, and is also involved in many functions such as cell division, cell motility and intracellular transportation. The three main filaments in the cytoskeleton are actin, microtubules and intermediate filaments, yet this complex system also consists of various binding proteins which cross-link and bundle the filaments, as well as motor proteins which move along the filaments. The polymerization of the different components is highly regulated by the cell according to specific needs. The mechanical properties of networks of these polymers are important for understanding cell mechanics and, indirectly, cancer therapy. Our measurements of the elastic storage and viscous loss moduli of a model system comprising microtubules and F-actin has provided novel results that suggest some of the design principles by which the cell uses these materials. For more on this work, see here.

Older Research

A reconstruction of 3D real space data obtained by confocal microscopy. High to low mobility is shown as light to dark color, with unit arrows placed on the most mobile particles to indicate 3D direction of motion. Field of view is (22.6 μm)^2 by 5 μm.
Correlated motions in colloidal gels and glasses.Gels are macroscopic networks composed of microscopic or smaller subunits that are bonded to each other, either chemically or physically, so that the network spans the entire system. In a mixture of colloids and non-adsorbing polymers, an attraction is induced by the imbalance of osmotic pressure, caused by the depletion of polymers between colloidal particles, a purely entropic effect. We observe dynamical heterogeneities in this system. For more information on this research, see here and here.