Tania Valdes-Gonzalez, Naoko Goto-Inoue, Takahiro Hayasaka, Hironobu Ishiyama, Mitsutoshi Setou and Takao Taki
Glycosphingolipids and phospholipids from white matter of human hippocampus, were analyzed by a sequential procedure of two-dimensional TLC (2d-TLC), transference of separated lipids to a PVDF membrane by a TLC-Blot equipment and Mass spectrometry (MS) analysis with an ion-trap type MALDI-TOF equipment. The method is simple and quick; very small amount of sample (0.1 mg of brain tissue) is enough to analyze all lipid components. The 2d-TLC provided excellent separation and the MS analyses allowed identifying the characteristic profile of molecular species for individual glycolipids and phospholipids. The results of MS analyses on gangliosides showed that di- and tri-sialogangliosides are richer in d20:1 sphingosine-containing ceramide than monosialogangliosides, suggesting the presence of sialylation selection after GM1 gangliosides. Then we analyzed ganglioside molecular species obtained from different brain regions by using MS imaging technology. The MS images of individual gangliosides provided clear visual profiles in terms of molecular species distribution. The imaging profiles were region dependent and also indicated that the sialyltransferase toward GM1 ganglioside prefers to select d20:1 sphingosine containing molecule. This technology provides visual characterization of individual phospholipid and glycosphingolipid molecular species and informs us about the metabolic characterization of target tissue, opening a new gate for colorful lipidomics research.