Live single-cell metabolomics of tryptophan and histidine metabolites in a rat basophil leukemia cell.

A direct and rapid metabolic analysis of a live single cell was performed by live single-cell video-mass spectrometry. The contents of the cytoplasm and a granule were sucked into a nano-electrospray ionization (nano-ESI) tip, and were directly introduced into a Q-TOF mass spectrometer by nano-spray after the addition of an ionization solvent. The metabolic pathways and the locations of tryptophan and histidine metabolites were traced by this method for a cultured rat basophil leukemia cell line (RBL-2H3). The t-values of detected peaks by a t-test between the different location, e.g. cytoplasm and a granule, revealed the molecular localization of each MS peak. A direct and quick metabolomic analysis of a living cell under simultaneous video-microscopic observations was innovated.