Fig. 10: Lipidomic analyses of Lipe+/+ and Lipe−/− retina and RPE/choroid mouse tissues (n = 5 per group).
a Mass spectra of the TAGs of Lipe+/+ RPE/choroid (spectrum 1), Lipe−/− RPE/choroid (2), Lipe+/+ retina (3) and Lipe−/− retina (4) showing different peaks in Lipe−/− retina (purple oval). b Trace 1: An extracted ion chromatogram (EIC) of an analytical ion with m/z 575.501 that can originate from either DAGs or TAGs. The existence of several chromatographic peaks with different retention times (RTs) implies the presence of several parent compounds. The peak with RT 6.43 min is a true DAG with an elemental composition C37H66O4 detected as an (M − H2O + H)+ ion, while peaks with RT 13.23 min and 15.19 min are spontaneously in-source fragmented TAGs with the same C37H66O4 moiety. Trace 2: An EIC of an ion m/z 883.779. The main peaks with RT 13.06 min and 14.87 min belong to a TAG C57H102O6 detected as an (M + H)+ adduct. The existence of two major chromatographic peaks implies the presence of two major isobaric structural isomers of the compound. Trace 3: An EIC of an analytical ion m/z 369.352. The ion is characteristic of both Chl and CEs. The main peak with RT 6.36 min belongs to Chl (C27H44O) detected as an (M − H2O + H)+ adduct. Note the presence of smaller peaks at 15.02 min and 16.43 min, which reveal the presence of, at least, two CEs. All LC—MS peaks are labeled as (RT; Peak area). c The Lipe+/+ and Lipe−/− retina samples were compared using OPLS-DA. d The Lipe+/+ and Lipe−/− RPE/choroid samples were compared and demonstrated a similar grouping pattern. Inactivation of Lipe caused noticeable, statistically significant changes in the balance between TAGs and DAGs (Panels e and f), and Chl and CEs (Panel g) in the retina, but not in the RPE/choroid. Calculated ratios in panels e–g were obtained for Lipe+/+ and Lipe−/− (n = 5 for each group). Data are presented as Mean ± SEM. Two-tailed Student’s t test.
