Events - Daily
March 04, 2013 >>
|Monday, March 04|
Sebastian Maerkl, EPFL Lausanne "Large-scale single cell analysis"
Observing cellular responses to perturbations is central to generating and testing hypothesis in biology. Time-lapse microscopy is a powerful tool for studying cellular phenotypes, but has been refractory to proteome-wide investigations. We developed a live-cell microarray integrated with a massively parallel microchemostat array to quantify microbial phenotypes in large-scale. Specifically, we quantified the spatio-temporal flux of the yeast proteome in response to environmental stresses by determining single-cell protein abundance and localisation changes in 4,085 GFP-tagged strains. Analysis of over 23,000 movies and 1.5 × 10^8 cells provided insight into the precise temporal orchestration of protein abundance and localisation changes in yeast. Highly dynamic re-location events are complementary to slow and persistent protein abundance changes, and together coordinate the cellular response on different time-scales. In particular, we observed that p-bodies rapidly form in response to UV-induced DNA/RNA damage. Through the precise spatio-temporal analysis of over 500 deletion - GFP-tagged strains we could determine that the p-body response is an intricate component of the DNA damage response pathway, and link it to other previously identified components. In summary, we developed a methodology for large-scale single-cell analysis and applied it to the characterisation of the stress response pathways in S. cerevisiae. Our approach is broadly applicable, and we have shown that other microbes such as E. coli, M. smegmatis, and S. pombe, can also be analysed on our platform.
Joseph Henry Room · 12:00 p.m.– 1:00 p.m.
Condensed Matter Seminar - Collin Broholm, The Johns Hopkins University - "Continuum Excitations in Crystalline Magnets"
I present inelastic neutron scattering data from one- two- and three-dimensional insulating magnetic materials at low temperatures that do not display a coherent resonant mode of excitation. Instead, momentum resolved spectra take the form of bounded continua. I interpret the spectra as evidence for fractionalization of a spin flip into distinct quasi-particles.
The unifying feature of the quantum magnets examined is a ground state that does not break rotational or translational symmetries – conventional Neel order having been disfavored by competing interactions and/or low dimensionality. I discuss the nature of the quasi-particles based on the neutron scattering data, the underlying lattice structure, and the spin Hamiltonian.
The talk features inelastic neutron scattering data from novel instrumentation at the NIST Center for Neutron Research and the ORNL Spallation Neutron Source, which is dramatically improving our ability to probe atomic scale dynamics in condensed matter.
PCTS Seminar Room · 1:15 p.m.– 2:30 p.m.
CMT/HET Seminar - Ignacio Cirac, Max-Planck-Institute of Quantum Optics
PCTS Seminar Room · 2:30 p.m.– 4:00 p.m.