Alexander Pines Lecture: Imaging in biology and bio-medicine

Seminar | September 24 | 4-5 p.m. | 120 Latimer Hall

 Steven Chu, Department of Physics, Stanford University

 College of Chemistry

In recent years, new imaging probes such as organic dyes, green fluorescent proteins, optical tweezers, single molecule FRET, and super-resolution microscopy are having a profound impact on biological sciences. I will discuss our development of improved, photostable rare earth nanoparticles that allow the long-term, real time tracking of cargos in neurons. We observe that the number of engaged dynein motors changes repeatedly during the transport of a single cargo over a 900-micron trek. With the 1.0 millisecond time resolution, we are able to resolve single dynein steps, and argue that each dynein step requires the hydrolysis of two ATPs. Using the fluctuation theorem, we provide evidence that the dynein motor system operates well out of thermal equilibrium. If time permits, recent results in linear and non-linear ultrasound imaging will be presented.