Michael Eisen, UC Berkeley/LBNL, Activation and control of gene expression during early Drosophila development
Apr 21, 2014 · 4:15 p.m.– 5:15 p.m. · Carl Icahn Lab 101
Apr 22, 2014 · 4:30 p.m.– 5:30 p.m. · Carl Icahn Lab 101
Short reception follows seminar
Michael Levine, University of California, Berkeley, The Regulatory Genome in Animal Development and Evolution
Apr 23, 2014 · 4:00 p.m.– 5:00 p.m. · Lewis Thomas Lab 003
Whole-genome comparisons suggest that organismal complexity scales with increasingly sophisticated mechanisms of gene regulation rather than increases in gene number. The genomes of higher animals are riddled with enhancers, with the human genome containing as many as a million enhancers. Thus, a typical gene is embedded in a complex regulatory landscape containing tens or hundreds of enhancers. An important future challenge is to integrate genome technologies with quantitative imaging methods to elucidate the functional organization of the regulatory genome during dynamic cellular processes. I will discuss our first efforts to examine enhancer dynamics in living embryos.
Dan Needleman, Harvard Medical School, Self-Focusing of the Ran Gradient in Mitosis: Signaling, Mechanics, and Spindle Size
Apr 28, 2014 · 12:00 p.m.– 1:00 p.m. · Joseph Henry Room, Jadwin Hall
During spindle assembly, microtubules are highly enriched near chromatin by a process which, in many systems, is driven by the GTPase Ran. The Ran pathway has been proposed to establish a reaction-diffusion network that generates gradients in the behaviors of soluble proteins around chromatin, but the manner in which this happens is poorly understood. To better characterize the behavior of the Ran pathway, we developed a novel form of fluorescence fluctuation spectroscopy capable of quantitatively measuring the concentration, diffusion, and interactions of soluble proteins simultaneously at hundreds of locations throughout cells. We use this technique to study the behaviors of soluble Ran, importin-alpha, importin-beta, RanBP1, RanGAP, and a variety of downstream cargo proteins throughout mitotic human tissue culture cells, and we investigate how the spatial organization of this network changes in response to perturbations. Our results suggest that a self-focusing of the Ran pathway is produced by an interplay between soluble gradients of upstream signaling molecules and the mechanics of the microtubule network they generate. This feedback has interesting implications for models of spindle assembly and the maintenance of spindle size.
Apr 28, 2014 · 4:15 p.m.– 5:15 p.m. · Carl Icahn Lab 101