This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Imaging mass spectrometry is developing into one of the new tools in biomedicine. Several approaches now allow for high resolution sensitive localization of biomolecules on tissue surfaces using Matrix Assisted Laser Desorption/Ionization. Often however, the resulting data display several unknown species with a spatial distribution that is indicative for a diseased or biochemically altered region on the tissue. A strategy that combines high resolution tandem mass spectrometry with spatial profiling has the potential to overcome this problem. For that reason at FOM we are developing new FTMS based mass spectral imaging instrumentation. In a first study we intend investigate a series of unknown endogenous neuropeptides in rat brain tissue sections that have been found with the FOM high resolution mass microscope. We are currently evaluating different MALDI sources for their suitability for imaging, paying specific attention to sensitivity, hard and software and tandem MS benefits targeting selected areas in a spatial profiling approach. The stigmatic imaging mass microscope at FOM1-4 is capable of rapidly generating images of tissue slices with submicron spatial resolution and reasonable mass resolution (5-10 k FWHM depending on the flatness of the surface). Figure 1 is an example of one such image from a rat brain As is common for these instruments, most of the peak identities are not known, but the vasopressin peak is assigned by its mass and by a spatial distribution consistent with the known functions of this neuropeptide. MS/MS information would, however, greatly improve the confidence in this assignment.
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