Lipid dynamics in zebrafish embryonic development observed by DESI-MS imaging and nanoelectrospray-MS

Abstract

The zebrafish Danio rerio is a model vertebrate organism for understanding biological mechanisms. Recent studies have explored using zebrafish as a model for lipid-related diseases, for in vivo fish bioassays, and for embryonic toxicity experiments. Mass spectrometry (MS) and MS imaging are established tools for lipid profiling and spatial mapping of biomolecules and offer rapid, sensitive, and simple analytical protocols for zebrafish analysis. When ambient ionization techniques are used, ions are generated in native environmental conditions, requiring neither sample preparation nor separation of molecules prior to MS. We used two direct MS techniques to describe the dynamics of the lipid profile during zebrafish embryonic development from 0 to 96 hours post-fertilization and to explore these analytical approaches as molecular diagnostic assays. Desorption electrospray ionization (DESI) MS imaging followed by nanoelectrospray (nESI) MS and tandem MS (MS/MS) were used in positive and negative ion modes, allowing the detection of a large variety of phosphatidylglycerols, phosphatidylcholines, phosphatidylinositols, free fatty acids, triacylglycerols, ubiquinone, squalene, and other lipids, and revealed information on the spatial distributions of lipids within the embryo and on lipid molecular structure. Differences were observed in the relative ion abundances of free fatty acids, triacylglycerols, and ubiquinone - essentially localized to the yolk - across developmental stages, whereas no relevant differences were found in the distribution of complex membrane glycerophospholipids, indicating conserved lipid constitution. Embryos exposed to trichloroethylene for 72 hours exhibited an altered lipid profile, indicating the potential utility of this technique for testing the effects of environmental contaminants.

Review and perspectives on the applications of mass spectrometry imaging under ambient conditions

“…(C) Single probe MSI images of phosphatidylcholine [PC (32:0) + H] + and [PC (34:1) + Na] + in inner medulla, outer medulla, and cortex regions of the kidney. [(A), (B), and (C) reproduced from refs Zou et al, Pirro et al, and Rao et al, respectively]…”

“…The degree of signal enhancement is highly dependent on the agent used as a dopant. Since the first report of a reactive agent, a series of agents with specific chemical reaction mechanisms have been tested: phenylboronic acid reacts with saccharides via a covalent cyclization reaction selective only towards cis‐diol functionalities, hydroxylamine has been employed for the rapid screening of oxime derivatized anabolic steroids, using betaine aldehyde to label cholesterol by derivatization on rat brain tissues, and more recently, spiking an additive such as silver nitrate in the solvent spray enables 1:1 ( 107 Ag/ 109 Ag) formation of silver lipid adducts from intact zebrafish embryos …”

“…Pirro and coworkers mapped lipid dynamics of five stages of embryonic development in zebrafish embryos by DESI‐MS imaging using a rapid and simple imaging approach . Live zebrafish embryos at 0–96 hours post‐fertilization (hpf) were individually transferred onto filter paper and taped onto a microscope glass slide, and DESI‐MS images were acquired from the embryo arrays (Figure B).…”

“…Lipidomic variations were observed upon the exposure of embryos to environmental pollutants using the animal carcinogen, trichloroethylene. After 72 h, altered lipid profiles with low‐intensity increases in ubiquinone, squalene and other minor differences in cytosolic lipids were found compared with embryos not exposed to the hepatotoxin …”

“…56 Pirro and coworkers mapped lipid dynamics of five stages of embryonic development in zebrafish embryos by DESI-MS imaging using a rapid and simple imaging approach. 48 Live zebrafish embryos at 0-96 hours post-fertilization (hpf) were individually transferred onto filter paper and taped onto a microscope glass slide, and DESI-MS images were acquired from the embryo arrays ( Figure 2B). In a multimodal lipidomic analytical approach, nESI-MS and nESI-MS/MS profiles of intact single embryos were collected after DESI-MS imaging with DMF/ACN, a non-destructive and tissue morphologically friendly solvent.…”