SPDM = Spectral Precision Distance Microscopy
Spectral Precision Distance Microscopy (SPDM) is a light microscopic approach of Spectrally Assigned Localization Microscopy that allows an optical resolution far beyond the conventional one. In genome research (mammals) SPDM emerged as a highly valuable tool for the study of the functional organization of nuclear nanostructure.
The principle of this "superresolution microscopy" technique is the use of "point-like" objects carrying different spectral signatures (e.g. fluorescent-dyes different in absorption and/or emission spectra; fluorescent dyes with different life-times; time dependence of luminescence, reversible bleaching behaviour etc. ).
So far, SPDM was applied in combination with confocal laser scanning microscopy as well as with SMI microscopy and even with ordinary widefield-techniques to address the following questions regarding the biophysics of the genome structure:
- study of the relative localization of the genes ANT2 and ANT3 on female X-chromosomes territories in 3D conserved human cell nuclei (Dietzel et al., 1999)
- studies on the 3D-nanostructure of the bcr/abl regions (chromosome 22 and 9) in cell nuclei of leukaemia (CML) patients (Esa et al., 2000). The distances and conformation angles measured could be used to test topological computer models of specific chromatin nanostructures.
- Conformational differences in the 3D-nanostructure of the immunoglobulin heavy-chain locus, a hotspot of chromosomal translocations in B lymphocytes. (Esa et al.,2001)
- measurements of the nuclear 3D-distances between selected sequences of the Prader-Willi-Region of chromosome 15 (Rauch et al., 2000/2008).
- Two-color intranuclear distance measurements of gene regions in human lymphocytes. (S. Fenz et al., 2007)
- SPDM: light microscopy with single-molecule resolution at the nanoscale (Reymann et al, 2008;P. Lemmer et al., 2008)
- Lokalisationsmikroskopie: Lichtoptische Nanoskopie. (C. Cremer, 2009)
- Light-Induced Dark States of Organic Fluochromes Enable 30 nm Resolution Imaging in Standard Media. (D. Baddeley et al., 2009)
- SALM: spectraly assigned localisation microscopy. (Kaufmann et al, 2008; Lemmer et al, 2009; Gunkel et al, 2009)
A number of further biomedical applications are currently under progress.
For more information, see publication list nanoscopy