Fig 1: Mass spectrometric imaging of the amyloid deposits. (A) Correlation between Congo red and MALDI images of a mouse intestine tissue sample. MALDI IMS distribution of specific ion peptides identified as Apoe with m/z values 1075.6, 1239.7, 1510.9, 1599.9, and 1743.9; Apoa4 with m/z values 1131.7, 1231.7, 1424.8, and 1461.8; and Apoa1 with m/z value 1299.7 correlates with Congo red positive staining. (B) MALDI IMS distribution of the same ion peptides detected on a different mouse intestine tissue sample. A predictive peptide (m/z 764.4) for Apoe protein was also detected correlating exclusively with the amyloid deposits. Overlay of Congo red and MALDI images shows co-localization of the different m/z species with extensive overlap with the amyloid deposits. MALDI IMS analysis was performed on the adjacent section to the Congo red staining section. The chromatic scale color bar indicates the relationship between the color of a peak displayed and the peak intensity in arbitrary units, with red and blue indicating the highest and lowest intensity color, respectively.