title: Optimization of whole-body zebrafish sectioning methods for mass spectrometry imaging.
abstract: Mass spectrometry imaging (MSI) methods and protocols have become widely adapted to a variety of tissues and species. However, the MSI literature contains minimal information on whole-body cryosection preparation for the zebrafish (ZF; Danio rerio), a model organism routinely used in developmental, toxicity, and carcinogenicity studies. The optimal medium for embedding and cryosectioning a whole organism or soft-tissue specimen for histological examination is a synthetic polymer mixture that is incompatible with MSI as a result of ion suppression. We describe the optimal methods and results for embedding and cryosectioning whole-body ZF for MALDI-MSI. We evaluated 13 distinct embedding media formulations and found a supportive hydrogel with the consistency of cartilage to be the optimal embedding medium. The hydrogel medium does not interfere with MSI data collection, aids in tissue stability, is readily available for purchase, and is easy to prepare and handle during cryosectioning. Additionally, we decreased the matrix cluster interference commonly caused by α-cyano-4-hydroxycinnamic acid by adding ammonium phosphate to the solvent spray solution. The optimized methods developed in our laboratory produced high-quality cryosections, as well as high-quality mass spectral images of sectioned ZF.
authors.affiliation: United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, FL 32561, USA. nelson.kimberly@epa.gov
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Nelson
authors.forename: Gabrielle J
authors.initials: GJ
authors.lastname: Daniels
authors.forename: John W
authors.initials: JW
authors.lastname: Fournie
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hemmer
mesh_terms: D000818:Animals; D003373:Coumaric Acids / Q000737:chemistry; D006652:Histological Techniques; D057054:Molecular Imaging; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D015027:Zebrafish / Q000033:anatomy & histology*
chemical_list: D003373:Coumaric Acids; C007175:alpha-cyano-4-hydroxycinnamate
keywords: MALDI-MS; ammonium phosphate; cryosectioning; hydrogel; whole-body imaging; zebrafish proteins; α-cyano-4-hydroxycinnamic acid