title: Single-cell lipidomics: characterizing and imaging lipids on the surface of individual Aplysia californica neurons with cluster secondary ion mass spectrometry.
abstract: Neurons isolated from  Aplysia californica , an organism with a well-defined neural network, were imaged with secondary ion mass spectrometry, C(60)-SIMS. A major lipid component of the neuronal membrane was identified as 1-hexadecyl-2-octadecenoyl-sn-glycero-3-phosphocholine [PC(16:0e/18:1)] using tandem mass spectrometry (MS/MS). The assignment was made directly off the sample surface using a C(60)-QSTAR instrument, a prototype instrument that combines an ion source with a commercial electrospray ionization/matrix-assisted laser desorption ionization (ESI/MALDI) mass spectrometer. Normal phase liquid chromatography mass spectrometry (NP-LC-MS) was used to confirm the assignment. Cholesterol and vitamin E were also identified with in situ tandem MS analyses that were compared to reference spectra obtained from purified compounds. In order to improve sensitivity on the single-cell level, the tandem MS spectrum of vitamin E reference material was used to extract and compile all the vitamin E related peaks from the cell image. The mass spectrometry images reveal heterogeneous distributions of intact lipid species, PC(16:0e/18:1), vitamin E, and cholesterol on the surface of a single neuron. The ability to detect these molecules and determine their relative distribution on the single-cell level shows that the C(60)-QSTAR is a potential platform for studying important biochemical processes, such as neuron degeneration.
authors: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States. melissa.passarelli@gmail.com
authors: Melissa K
authors: MK
authors: Passarelli
authors: Andrew G
authors: AG
authors: Ewing
authors: Nicholas
authors: N
authors: Winograd
mesh_terms: D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D002784:Cholesterol / Q000032:analysis; D008055:Lipids / Q000032:analysis*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000032:analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018629:Spectrometry, Mass, Secondary Ion; D053719:Tandem Mass Spectrometry; D014810:Vitamin E / Q000032:analysis
chemical_list: D008055:Lipids; D010713:Phosphatidylcholines; D014810:Vitamin E; D002784:Cholesterol