Fig. 6.

Differential MALDI spectra reveal compensatory PCs generated in Adipor1^−/− and the Mfrp^rd6 retina. Difference spectra show relative abundances detected by MALDI IMS. A: Molecules more abundant in WT retina versus Adipor1^−/− retina are presented in the upper part of the graph, while molecules more abundant in the Adipor1^−/− retina are displayed at the bottom. 22:6- and/or VLC-PUFA–containing PCs are much more abundant in WT while 20:4-containing PCs are increased in the mutant retina. The regions from which the spectra are extracted are shown in the insets H and E (top) and MALDI (bottom), showing PC40:6 (m/z = 856.6, red) and PC38:4 (m/z = 832.6, green). B: The difference spectra of Mfrp^rd6 to WT. C: The difference spectra of Adipor1^−/− to Mfrp^rd6. Inset images show that in both mutants, the PRC layers contain both PCs 40:6 and 38:4 (yellow), whereas WT has clear separation of the two PCs species between PRC layer and inner retina layer. Reproduced, with permission, from the Federation of American Societies for Experimental Biology (57). IMS, imaging mass spectrometry; PRC, photoreceptor cell; VLC-PUFA, very long-chain PUFA.