Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Visualizing DNA using Tunable Nanoscale Confinement

Sabrina Leslie
McGill University

Date: Thursday, Jan. 23, 2014
Time: 10:30 AM
Location: Stirling 401


A wide range of physiological processes rely on weak intermolecular interactions and slow dynamics that occur at high concentrations, over long time periods, and often under confinement. Probing such interactions and dynamics presents a challenge to fluorescence microscopy, the work horse for resolving biological processes at the molecular scale.

To address this challenge, we present new microscopy methodologies which, by imposing tunable nano-scale confinement, enable new biophysical measurements under previously inaccessible conditions. In particular, we are interested in directly visualizing DNA conformations and dynamics, and their interactions with other DNA and protein molecules, over a continuum of applied confinement from the nanometer to micrometer scale. In one experimental study, we visualize the conformations, diffusion and free energy of confinement experienced by DNA molecules, as a function of applied confinement. In a second experimental study, we combine tunable vertical and transverse applied confinement to dynamically manipulate DNA conformations in-situ. We demonstrate the ability to dynamically template extended DNA molecules into nano channels for optical interrogation and potentially genome mapping. Third, we create custom DNA constructs for new biophysical experiments which will enable superhelicity-driven transitions in DNA topology to be visualized directly in conjunction with protein-DNA binding. How conformational fluctuations in DNA regulate transcription and gene expression remains an open and compelling question which our technology development aims to address.