Jul. 22, 2013
We explore the potential of a novel imaging method to exploit differential susceptibility of biological tissue to erosion by Focused Ion Beam (FIB) milling. The contents of a given cell (nucleus, Golgi apparatus, vacuoles) have different physical compositions and will ablate differentially under the ion beam. Sequential fine slices of frozen cells have been ablated, after which slice-by-slice image analysis of the extracted ablation vectors is back-converted to a FIB susceptibility parameter. moreJul. 09, 2013
The extraction of quantities from image data represents a common yet powerful way of obtaining information about the imaged objects. In the last decade or so, it has come to play an important role in single molecule microscopy data analysis, where attributes of a fluorescent molecule such as its location need to be estimated accurately from an image. Different estimators can be used to determine the quantities of interest with varying levels of accuracy. However, even when an accurate estimator is used, the obtainable accuracies are fundamentally limited by the fact that the estimation is carried out on image data that has been deteriorated by pixelation and detector noise. We describe here an imaging method that produces image data from which quantities of interest can be estimated with accuracies significantly higher than those that could be expected when the quantities are estimated from conventionally acquired image data. Focus is given to a particular implementation that minimizes the deteriorative effects of both pixelation and detector noise. moreJun. 18, 2013
Correlative light and electron microscopy (CLEM) combines the versatility of fluorescence microscopy (FLM) with the spatial resolution of transmission electron microscopy (TEM). For the analysis of tissues single resin or cryo-sections are incubated with fluorochrome- and gold-labeled probes. Areas of interest are selected at the FLM, and analyzed in the TEM at high resolution. This way, fluorescence is directly correlated to subcellular structures and/or corresponding immunogold signals. moreJun. 11, 2013
For excitable cells in which signaling events occur in milliseconds, a mathematical formalism for pixel-wise fitting generates virtually pixel noise-free image sequences from high-speed 2-dimensional confocal data. This approach provides novel insight into cardiac excitation-contraction coupling and its pathophysiology. Such an analytical approach can be extended into other biological systems to uncover otherwise inaccessible features of subcellular signal transduction in living cells.
moreJun. 07, 2013
The early growth stage and growth evolution to a unique gold (Au) honeycomb nano-network on Si(111)7×7 at room temperature have been studied by direct filled-state and empty-state imaging by scanning tunneling microscopy (STM). The gold honeycomb structure is made up of six triangular gold clusters around the corner hole interconnected to one another in the dimer rows of the Si(111)7×7 substrate. moreApr. 29, 2013
The plasma membrane (PM) is a selective barrier that separates cells from their environment and acts as signalling platform. Many PM proteins localize into characteristic domains but the molecular basis for their segregation is under debate. Using a combination of total internal reflection fluorescence microscopy and 2D deconvolution we visualized a large set of PM proteins in budding yeast. We found that the yeast PM self-organizes into numerous domains through weak protein-lipid interactions.
moreApr. 22, 2013
Scattering-type near-field optical microscopy (s-SNOM) is a powerful technique to image nano objects. It can be employed in a broad spectral range, namely the complete infrared region spanning from the terahertz range up to the visible range. In this article we describe a system which utilizes a free-electron laser as a spectrally narrow and widely tunable source of infrared radiation. This system was employed to study electrons confined in self-assembled InAs quantum dots. We spatially resolved single quantum dots upon resonant excitation of transitions between discrete energy levels of the confined electrons. moreApr. 16, 2013
We developed a new approach using cryo-correlative light and scanning transmission electron microscopy allowing analysis of targeted in situ intracellular ions and water measurements at the ultrastructural level within domains identified by examination of specific GFP-tagged proteins . We illustrate the potential of this approach by investigating changes in water and ion content in nuclear domains identified by GFP-tagged proteins in cells stressed by Actinomycin D treatment and controls. more