title: High-resolution quantitative imaging of mammalian and bacterial cells using stable isotope mass spectrometry.
abstract: BACKGROUND
  Secondary-ion mass spectrometry (SIMS) is an important tool for investigating isotopic composition in the chemical and materials sciences, but its use in biology has been limited by technical considerations. Multi-isotope imaging mass spectrometry (MIMS), which combines a new generation of SIMS instrument with sophisticated ion optics, labeling with stable isotopes, and quantitative image-analysis software, was developed to study biological materials.
  
  
  RESULTS
  The new instrument allows the production of mass images of high lateral resolution (down to 33 nm), as well as the counting or imaging of several isotopes simultaneously. As MIMS can distinguish between ions of very similar mass, such as 12C15N- and 13C14N-, it enables the precise and reproducible measurement of isotope ratios, and thus of the levels of enrichment in specific isotopic labels, within volumes of less than a cubic micrometer. The sensitivity of MIMS is at least 1,000 times that of 14C autoradiography. The depth resolution can be smaller than 1 nm because only a few atomic layers are needed to create an atomic mass image. We illustrate the use of MIMS to image unlabeled mammalian cultured cells and tissue sections; to analyze fatty-acid transport in adipocyte lipid droplets using 13C-oleic acid; to examine nitrogen fixation in bacteria using 15N gaseous nitrogen; to measure levels of protein renewal in the cochlea and in post-ischemic kidney cells using 15N-leucine; to study DNA and RNA co-distribution and uridine incorporation in the nucleolus using 15N-uridine and 81Br of bromodeoxyuridine or 14C-thymidine; to reveal domains in cultured endothelial cells using the native isotopes 12C, 16O, 14N and 31P; and to track a few 15N-labeled donor spleen cells in the lymph nodes of the host mouse.
  
  
  CONCLUSIONS
  MIMS makes it possible for the first time to both image and quantify molecules labeled with stable or radioactive isotopes within subcellular compartments.
authors.affiliation: National Resource for Imaging Mass Spectrometry, Harvard Medical School and Department of Medicine, Brigham and Women's Hospital, Cambridge, MA 02139, USA. cpl@harvard.edu
authors.forename: Claude
authors.initials: C
authors.lastname: Lechene
authors.forename: Francois
authors.initials: F
authors.lastname: Hillion
authors.forename: Greg
authors.initials: G
authors.lastname: McMahon
authors.forename: Douglas
authors.initials: D
authors.lastname: Benson
authors.forename: Alan M
authors.initials: AM
authors.lastname: Kleinfeld
authors.forename: J Patrick
authors.initials: JP
authors.lastname: Kampf
authors.forename: Daniel
authors.initials: D
authors.lastname: Distel
authors.forename: Yvette
authors.initials: Y
authors.lastname: Luyten
authors.forename: Joseph
authors.initials: J
authors.lastname: Bonventre
authors.forename: Dirk
authors.initials: D
authors.lastname: Hentschel
authors.forename: Kwon Moo
authors.initials: KM
authors.lastname: Park
authors.forename: Susumu
authors.initials: S
authors.lastname: Ito
authors.forename: Martin
authors.initials: M
authors.lastname: Schwartz
authors.forename: Gilles
authors.initials: G
authors.lastname: Benichou
authors.forename: Georges
authors.initials: G
authors.lastname: Slodzian
mesh_terms: D017667:Adipocytes / Q000737:chemistry / Q000166:cytology; D000818:Animals; D001973:Bromodeoxyuridine; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D042783:Endothelial Cells / Q000737:chemistry / Q000166:cytology; D020563:Gammaproteobacteria / Q000737:chemistry / Q000166:cytology; D007554:Isotopes / Q000737:chemistry; D013058:Mass Spectrometry / Q000295:instrumentation* / Q000379:methods*; D051379:Mice; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D051381:Rats
chemical_list: D007554:Isotopes; D011506:Proteins; D012313:RNA; D004247:DNA; D001973:Bromodeoxyuridine