Supplementary Figure 4: 13C Glucose incorporation in host lipids during Myco-GEM culture.
From: An explant technique for high-resolution imaging and manipulation of mycobacterial granulomas
Granulomas were cultured using Myco-GEM medium supplemented with 12C glucose (top) or 13C glucose (bottom) and analyzed by MALDI-MS. (a) After 4 d of culture in 13C, a + 3 mass shift was observed in the 885.55 m/z peak corresponding to phosphatidylinositol (PI) 38:4. (b) Granulomas were cultured for 4 d in 12C glucose followed by 2 d in 13C glucose. Following the 2-d incubation in 13C, a similar + 3 mass shift could be observed for the 885.55 m/z peak corresponding to phosphatidylinositol (PI) 38:4. (c) MS/MS analysis of ion 885.55 m/z shows that the two fatty acid chains are arachidonic acid (303.23 m/z) and stearic acid (283.26 m/z). (d) MS/MS analysis of ion 888.56 m/z, corresponding to 13C-labelled PI 38:4, and associated fragmentation patterns show incorporation of the labeled carbons in the glycerol moiety of PI 38:4.
