Phone (Lab): 401-863-2156
email: patrick_oakes @ physics . brown . edu

• Boston College (2000-2004) - B.Sc.
• Brown University (2004-2005) - M.Sc Physics
• Brown University (2005 - present)

I am currently beginning a research project focusing on integrin mediated force generation in migrating T cells. Migration is is an important cellular process that has been shown to be involved in a wide range of applications including tissue repar, immune surveillance, vascular diseases, chronic inflammations and even things like cancer, multiple sclerosis and mental retardation. In our research we focus on the migration of T cells which through a cyclic process of protrustion, adhesion and retraction are able to migrate over substrates. We will be using Total Internal Reflection Fluorescence (TIRF) to probe the role of integrin and other proteins in the process of migration and adhesion. The TIRF system will focus on the thin adhesion layer that it is in direct connection with the substrate allowing distinct visualization of only those integrin that are involved in the migration process. In addition we will take adavantage of the laboratory's Atomic Force Microscope (AFM) to probe the elastic nature and response of the migrating cells.

In my previous research I worked on the phase transition of actin. Actin is one of the most abundant proteins in the cytoskeleton. It comes in two forms, G-actin, a globular form, and F-actin, a filament consisting of G-actin monomers connected together. These filaments can have their length regulated through the use of the capping protein gelsolin. F-actin can then be modeled as a system of semiflexible rods which behaves as a liquid crystal. Using the theories of people like Onsager and Flory this system is predicted to undergo a first order phase transition from the isotropic (completely unaligned) to nematic (aligned) state. By controlling the average filament length and the concentrations of the F-actin solution, both isoptropic and nematic states are easily produces. Curiously though the transition between the two states seemed to be continuous in both concentration and alignment, showing none of the characteristics of a first order transition. Recently we have shown that a first order transition, that is to say one discontinuous in both concentration and alignment, can be found for solutions that are highly concentrated and which consist of short average filament lengths. This is the first clear instance of a first order phase transition in solutions of F-actin.

These solutions of F-actin exhibit tactoidal droplets of nematic F-actin in a background of isotropic F-actin. The tactoids appear in shape like an American football with two point defects at either end. The director field is tangent to the surface at all points and connects the two point defects. The formation of these tactoids is achieved by two methods: nucleation and growth, and spinodal decomposition. We are currently studying these growth methods and what they tell us about the solution.

Morin, N. A., Oakes, P. W., Hyun, Y.-M., Lee, D., Chin, E. Y., King, M. R., Springer, T. A., Shimaoka, M., Tang, J. X., Reichner, J. S., Kim, M.,
Nonmuscle Myosin Heavy Chain IIA Mediates Integrin LFA-1 De-adhesion During T Lympphocyte Migration
J. Exp. Med. 205, 195-205 (2008) (PDF)

Viamontes, J., Oakes, P. W., and Tang, J. X.,
The Isotropic to Nematic Liquid Crystalline Phase Transition of F-actin Varies from Continuous to First Order.
Phys. Rev. Lett. 97, 118103 (2006) (PDF)