Recent Advances in Shotgun Lipidomics and Their Implication for Vision Research and Ophthalmology

Abstract

In the past decade, mass spectrometry (MS) has made tremendous advances toward the profiling and identification of lipids from biological samples. MS is attractive for the simplicity it offers toward total profiling of lipids, the identification and characterization of individual entities directly after extraction from complex biological mixtures utilizing an infusion mode. Fundamentally, two types of mass analyzers exist, depending upon whether the fragment ion resolution and analysis occurs in space domain or in time domain within the mass spectrometer. Compared to MS, chromatographic methods are cumbersome. Nuclear magnetic resonance, which provides unequivocal elucidation of structures, necessitates much higher absolute amount and demands purity of lipids. We present here an account of recent developments in class-specific lipid identification strategies, targeted and untargeted lipid analyses, identification and de novo structure elucidation using mass spectrometric and combinatorial chemical derivatization and MS. We have reviewed the strategies with emphasis for spatial domain fragment resolution mass analyzers enabling analysis of lipids in a class-specific manner. We also provide a brief account of database and bioinformatic tools that have been recently developed toward profiling, identification and quantification of lipids in complex biological mixtures.

Isolation and Identification of Allelochemicals from Ascocarp of Tuber Species

“…A possibility to analyse a large pool of compounds simultaneously has greatly improved the knowledge of many aspects, and the scientifi c papers on-omic studies are in exponential rise. The use of less invasive extraction and analysis protocols is well accepted and produces less chemical artefacts Tang et al 2011 ;Han et al 2012 ;Bhattacharya 2013 ;Brenna 2013 ;Fouillen et al 2013 ;Hartler et al 2013 ;Lam and Shui 2013 ;Schone et al 2013 ).…”

Lipidomic mass spectrometry and its application in neuroscience

“…Electrospray ionization mass spectrometry enables the identification and quantification of the cellular or tissue lipidomes directly from crude extracts of cell, tissue or organ samples [21][22][23] . The mass spectrometers that resolve fragments of entrant precursor ions of biomolecules in space domains enable identification and quantification in a class specific manner, referred to as automated shotgun lipid profiling [24] .…”

“…In mass spectrometric lipidomics, the quantification of lipids is ratiometric and performed with a synthetic or purified standard, often termed as internal standard usually in a two-step process [23][24][25] . The most abundant lipid species are quantified using direct comparison of the peak intensities to those of the added internal standard for the lipid class in the mass spectrum from the first step.…”

A Comparison of Trabecular Meshwork Sphingolipids and Ceramides of Ocular Normotensive and Hypertensive States of DBA/2J Mice

“…20,22 Briefly, in the first step, the most abundant lipid species were quantified in a class-specific manner after isotopic correction (in direct comparison of peak intensities with the added internal standard for each class), which was subsequently used to quantify less abundant species in the second step. 19,21,22 All lipid standards were procured from Avanti Polar Lipids, Albaster, Alabama. The quantitative standards used were N-oleoyl-D-erythro-sphingosylphosphorylcholine (Catalog number 860587; molecular mass 729.08) for the sphingomyelin class, D-erythro-sphingosine (Catalog number 860490; molecular mass 299.5) for the sphingoid base class, D-erythro-sphingosine-1-phosphate (Catalog number 860402; molecular mass 379.47) for the sphingoid base -1-phosphate class, and N-oleoyl-D-erythrosphingosine (Catalog number 860519; molecular mass 563.94) for ceramides.…”

“…We utilized standardized triple quadrupole instrument parameters for detection of lipid species by mass spectrometry. 19 Briefly, the sphingomyelin and sphingoid base species were detected by a neutral loss scan of m/z 213.2 and 48 in the positive ion mode with collision energies of 50 and 18 V, respectively. Ceramide and sphingoid base-1-phosphate species were detected in the negative ion mode by neutral loss scan of m/z of 256.2 at collision energy of 32 V, and precursor ion scan for m/z 79.1 at collision energy of 24 V, respectively.…”