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Title: Subcellular-level resolution MALDI-MS imaging of maize leaf metabolites by MALDI-linear ion trap-Orbitrap mass spectrometer

A significant limiting factor in achieving high spatial resolution for matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) imaging is the size of the laser spot at the sample surface. We present modifications to the beam-delivery optics of a commercial MALDI-linear ion trap-Orbitrap instrument, incorporating an external Nd:YAG laser, beam-shaping optics, and an aspheric focusing lens, to reduce the minimum laser spot size from ~50 μm for the commercial configuration down to ~9 μm for the modified configuration. This improved system was applied for MALDI-MS imaging of cross sections of juvenile maize leaves at 5-μm spatial resolution using an oversampling method. There are a variety of different metabolites including amino acids, glycerolipids, and defense-related compounds were imaged at a spatial resolution well below the size of a single cell. Such images provide unprecedented insights into the metabolism associated with the different tissue types of the maize leaf, which is known to asymmetrically distribute the reactions of C4 photosynthesis among the mesophyll and bundle sheath cell types. The metabolite ion images correlate with the optical images that reveal the structures of the different tissues, and previously known and newly revealed asymmetric metabolic features are observed.
 [1] ;  [2] ;  [1] ;  [1]
  1. Iowa State Univ., Ames, IA (United States); Ames Lab., Ames, IA (United States)
  2. Iowa State Univ., Ames, IA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
IS--J 8571
Journal ID: ISSN 1618-2642; PII: 8460
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Analytical and Bioanalytical Chemistry
Additional Journal Information:
Journal Volume: 407; Journal Issue: 8; Journal ID: ISSN 1618-2642
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
Country of Publication:
United States
47 OTHER INSTRUMENTATION; 59 BASIC BIOLOGICAL SCIENCES mass spectrometry imaging; metabolite; maize