Coupling Stable Isotope Labeling and Liquid Chromatography-Trapped Ion Mobility Spectrometry-Time-of-Flight-Tandem...

There is a need to better understand lipid metabolism during mosquito ovarian development. Lipids are the major source of energy supporting ovarian follicles development in mosquitoes. In this paper, we describe the complementary use of stable isotope labeling (SIL) and high-resolution mass spectrometry-based tools for the investigation of de novo triglycerides (TG) and diglycerides (DG) during the ovarian previtellogenic (PVG) stage (4-6 days posteclosion) of female adult Aedes aegypti. Liquid chromatography coupled to high-resolution trapped ion mobility spectrometry-parallel accumulation sequential fragmentation-time-of-flight tandem mass spectrometry (LC-TIMS-PASEF-TOF MS/MS) allowed the separation and quantification of nonlabeled and ²H/¹³C-labeled TG and DG species. Three SIL strategies were evaluated (H₂O/²H₂O with 50:50 and 95:5 mixtures, ¹³C-sucrose, and ¹³C-glucose). Results showed wide applicability with no signs of lipid ovarian impairment by SIL induced toxicity. The analytical workflow based on LC-TIMS-TOF MS/MS provided high confidence and high reproducibility for lipid DG and TG identification and SIL incorporation based on their separation by retention time (RT), collision cross section (CCS), and accurate m/z. In addition, the SIL fatty acid chain incorporation was evaluated using PASEF MS/MS. The ²H/¹³C incorporation into the mosquito diet provided information on how TG lipids are consumed, stored, and recycled during the PVG stage of ovarian development.