UHPLC-IM-Q-ToFMS analysis of maradolipids, found exclusively in Caenorhabditis elegans dauer larvae

Abstract

Lipid identification is one of the current bottlenecks in lipidomics and lipid profiling, especially for novel lipid classes, and requires multidimensional data for correct annotation. We used the combination of chromatographic and ion mobility separation together with data-independent acquisition (DIA) of tandem mass spectrometric data for the analysis of lipids in the biomedical model organism Caenorhabditis elegans. C. elegans reacts to harsh environmental conditions by interrupting its normal life cycle and entering an alternative developmental stage called dauer stage. Dauer larvae show distinct changes in metabolism and morphology to survive unfavorable environmental conditions and are able to survive for a long time without feeding. Only at this developmental stage, dauer larvae produce a specific class of glycolipids called maradolipids. We performed an analysis of maradolipids using ultrahigh performance liquid chromatography-ion mobility spectrometry-quadrupole-time of flight-mass spectrometry (UHPLC-IM-Q-ToFMS) using drift tube ion mobility to showcase how the integration of retention times, collisional cross sections, and DIA fragmentation data can be used for lipid identification. The obtained results show that combination of UHPLC and IM separation together with DIA represents a valuable tool for initial lipid identification. Using this analytical tool, a total of 45 marado- and lysomaradolipids have been putatively identified and 10 confirmed by authentic standards directly from C. elegans dauer larvae lipid extracts without the further need for further purification of glycolipids. Furthermore, we putatively identified two isomers of a lysomaradolipid not known so far. Graphical abstract

OAC-39 is an O-acyltransferase required for the synthesis of maradolipids in the dauer larva of C. elegans

“…Less represented is the class of monoacyltrehaloses or "lyso-maradolipids" in which trehalose is singly acylated (18). As described by us and later confirmed by other groups, both classes are present only in dauer animals and are not detectable in other developmental stages (17)(18)(19). A shared feature of both classes is a specific fatty acid composition.…”

“…A shared feature of both classes is a specific fatty acid composition. They show a pronounced enrichment of monomethyl branched-chain fatty acids (mmBCFAs) (17)(18)(19), which reaches up to approximately 66 mol% in maradolipids (17).…”

Ion Mobility Mass Spectrometry for the Separation and Characterization of Small Molecules

“…In terms of metabolite screening and characterization, − LC-IMS-CID-MS provides four dimensions (LC, IMS, MS, and MS/MS) to directly study the metabolic activity of priority nontargeted features . The combination of UPLC and IM separation with data-independent acquisition (DIA) represents the value for initial lipid identification . Picmanova et al recently combined zwitterionic-phase hydrophilic interaction chromatography (HILIC) with DTIMS-QTOF to establish a fast and nontargeted metabolomics workflow with extensive metabolomic coverage.…”

Quo Vadis Caenorhabditis elegans Metabolomics—A Review of Current Methods and Applications to Explore Metabolism in the Nematode

“…Recently, analysis of maradolipids from dauer larvae using LC-IM-MS has been performed. DIA was combined with IM separation to obtain fragmentation data of maradolipids, which led to the identification of 45 marado- and lysomaradolipids directly from dauer larvae lipid extracts, without the need of further prior purification of glycolipids [ 135 ].…”