Colloquium
Ehrenfestii
»» 1912-2012 ««
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20 Jun |
W. Moerner (Stanford) |
Single Molecules as Light Sources for Super-resolution Imaging and Probes for Single Biomolecules in Solution |
Since the first optical detection and spectroscopy of a single molecule in condensed matter (PRL (1989)), much has been learned about the ability of single molecules to probe local nanoenvironments and individual behavior in biological and nonbiological materials in the absence of ensemble averaging that can obscure heterogeneity. Single-molecule fluorescence imaging enables biophysical measurements in cells without ensemble averaging, but also yields enhanced spatial resolution beyond the diffraction limit when combined with optical control of the single emitters to maintain sparse concentrations. Using the native photoinduced blinking and switching of EYFP (Dickson et al., Nature (1997)) we achieve sub-40 nm super-resolution imaging of protein structures in the bacterium Caulobacter crescentus: the actin-like protein MreB (Biteen et al., Nat. Meth. (2008)), the DNA binding protein HU (Lee et al., Biophys. J.Lett. (2011)), and the ParA division spindle (Ptacin et al., Nat. Cell Biol. (2010)). A new photoactivatable small-molecule emitter can be targeted to specific proteins in living cells to provide super-resolution images of protein superstructures (Lee et al., JACS (2010)). In terms of methods, a new scheme for 3D imaging based on a double-helix point spread function enables quantitative tracking of single mRNA particles in living yeast cells with 15 ms time resolution and 25-50 nm spatial precision (Thompson et al., PNAS (2010)), and this approach has been used to define the 3D spatial structure in bacterial (Lew et al., PNAS (2011)) and mammalian cells. To study a single biomolecule in solution without surface attachment or confinement, a machine called the Anti-Brownian ELectrokinetic (ABEL) trap provides real-time suppression of Brownian motion, and this device has been used to explore the photodynamics of single copies of the antenna protein allophyocyanin (Goldsmith et al., Nature Chem. (2010)), to extract ATP number distributions for single multi-subunit enzymes (Jiang et al., PNAS (2011)), and to explore the action of single redox enzymes (Goldsmith et al., PNAS (2011)). The examples provided here illustrate some of the frontiers where single-molecule spectroscopy and imaging are yielding new insights into the behavior of complex systems.
The Colloquium Ehrenfestii takes place Wednesday evenings starting at 19:30 hours in the main auditorium of the Oort building. Before the Colloquium, there is a common dinner in the canteen located on the ground floor of the Oort building. This dinner starts at 18:00 hours sharp and is free of charge, under the condition that one attends the colloquium and that one has made a reservation before noon on the Tuesday preceding the colloquium.
The registration form is only accessible from within the University (to block spammers); if you would like to register for the dinner from outside the University, please send an email to fran@lorentz.leidenuniv.nl
After 6 pm the revolving doors of the Oort building, approached by the long bridge alongside the Kamerlingh Onnes Laboratory, are locked and one should instead use the sliding doors directly adjacent to the Huygens building: these can be opened with an electronic key (seek help from locals).
Colloquium Ehrenfestii in 2012 20 June
W. Moerner (Stanford)
Single Molecules as Light Sources for Super-resolution Imaging and Probes for Single Biomolecules in Solution
09 May
S. Sachdev (Harvard)
Quantum entanglement and the phases of matter
04 Apr
L. Mahadevan (Harvard)
The geometry, continuum and statistical mechanics of ribbons
14 Mar
S. Havlin (Bar-Ilan)
Percolation of Network of Networks
29 Feb
M. Shaposhnikov (Lausanne)
Is there a new physics between electroweak and Planck scale?
08 Feb
Ivo van Vulpen (NIKHEF)
The search for the Higgs boson at the LHC.
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