Visualization of biomolecules in the eyestalk of the blue swimming crab, Portunus pelagicus, by imaging mass spectrometry using the atmospheric-pressure mass microscope

Abstract

We have developed an imaging mass spectrometer-the atmospheric-pressure mass microscope-with high spatial resolution, which is composed of an atmospheric pressure ion-source chamber for matrix-assisted laser desorption/ionization (AP-MALDI) and a quadrupole ion trap time-of-flight (QIT-TOF) mass spectrometer. The production of 2-dimensional mass spectrum intensity by the atmospheric-pressure mass microscope with a very fine scan pitch enables us to visualize the distribution of lipids and their metabolites in frozen sections without any specific probes or labels. In this study, we applied AP-MALDI-QIT-TOF imaging mass spectrometry to investigate the distribution of lipids in the compound eye-associated eyestalk of the blue swimming crab, Portunus pelagicus. The eyestalk of crustaceans responds to many signaling substances, and most of these substances are involved in lipid metabolism. The merged ion image of five significant biomolecules clearly showed seven separate zones in the eye and eyestalk. The results indicate that the lipid components of each cell layer of the compound eye are different. This study provides information regarding lipid compositions and locations on real tissue that correlate with function. Imaging mass spectrometry (IMS) with high spatial resolution could thus be a powerful tool for imaging and measurement of various samples for a first molecular screening. © 2010 John Wiley & Sons, Ltd.