Mass spectrometry lipidomic analysis in bovine oocytes and embryos

Abstract

In vitro produced bovine embryos have lower quality, are less viable and more cryosensitive than in vivo derived embryos. Nowadays, expansion of commercial IVF main hindering is to obtain satisfactory pregnancy rates from cryopreserved IVF Zebu embryos. Many researches reported the relationship of lipids with fertility, their role in embryo development and cryosensitivy. The main objective of this project is to stablish a profile of the most abundant lipid classes, which are triglycerols (TAGs) and phospholipids, in bovine immature oocytes, in vitro matured oocytes, in vivo derived embryos, and in vitro produced embryos cultured with or without linoleic acid supplementation in culture medium. Harvested oocytes and embryos will have the zona pellucida eliminated by pronase 0.5% exposure, and will be stored in methanol/water 1:1 (v/v) solution at -80oC until analysis. Samples will be submitted to matrix-assisted laser desorption/ionization - time of flight mass spectrometry analysis (MALDI-TOF MS), using 2,5-dihydroxybenzoic acid (DHB) as matrix. Mass spectra collection will be performed in a MALDI-TOF (Micromass, Manchester, UK) mass spectrometer. Spectra will be processed (MassLynx v.4.0 Waters, Manchester, UK) in order to characterize the lipids and to perform chemiometric analysis (Pirouette 3.11, Infometrics Inc, EUA). Lipidomics of oocytes and embryos, which has not been yet reported in the literature, may contribute with strategies for cryopreserving in vitro produced bovine embryos. (AU)