Fig. 8.

DESI-MSI of retinal tissue sections: (a) schematic representation of the DESI-MSI in the range m/z 50–1,000. The impinging primary charged droplets desorb the surface metabolites into the secondary charged droplets, followed by the ion transfer to the mass spectrometer. The 2D-chemical map of docosahexaenoic acid (DHA; peak listed in red font) is shown with pixel size 200 µm. Raw MS spectrum across the pixels in a row is shown for (b) wild type retina tissue (c) arRP retina tissue and (d) ɑ-KG treated retina tissue. Red labels denote peaks assigned to identified metabolites and lipids. NL, normalization level; FA, fatty acid; PA, phosphatidic acid; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; PI, phosphatidylinositol; PS, phosphatidylserine.