Developmental phases of individual mouse preimplantation embryos characterized by lipid signatures using desorption electrospray ionization mass spectrometry

Abstract

Knowledge of the lipids present in individual preimplantation embryos is of interest in fundamental studies of embryology, in attempts to understand cellular pluripotency and in optimization of in vitro culture conditions necessary for the application and development of biotechnologies such as in vitro fertilization and transgenesis. In this work, the profiles of fatty acids and phospholipids (PL) in individual mouse preimplantation embryos and oocytes were acquired using an analytical strategy based on desorption electrospray ionization mass spectrometry (DESI-MS). The methodology avoids sample preparation and provides information on the lipids present in these microscopic structures. Differences in the lipid profiles observed for unfertilized oocytes, two-and four-cell embryos, and blastocysts were characterized. For a representative set of embryos (N= 114) using multivariate analysis (specifically principal component analysis) unfertilized oocytes showed a narrower range of PL species than did blastocysts. Two-and four-cell embryos showed a wide range of PLs compared with unfertilized oocytes and high abundances of fatty acids, indicating pronounced synthetic activity. The data suggest that the lipid changes observed in mouse preimplantation development reflect acquisition of a degree of cellular membrane functional and structural specialization by the blastocyst stage. It is also noteworthy that embryos cultured in vitro from the two-cell through the blastocyst stage have a more homogeneous lipid profile as compared with their in vivo-derived counterparts, which is ascribed to the restricted diversity of nutrients present in synthetic culture media. The DESI-MS data are interpreted from lipid biochemistry and previous reports on gene expression of diverse lipids known to be vital to early embryonic development.

Analysis of the Phospholipid Profile of Metaphase II Mouse Oocytes Undergoing Vitrification

“…In reproduction, similar methods have been used to compare phospholipid profiles of oocytes and embryos of several mammalian species [12]–[14], [32], [33]. Further investigation into the effect of cryopreservation on the phospholipid profile of oocytes and embryos in various species will generate insightful information regarding the biological importance of lipid conservation during this process.…”

Single-cell mass spectrometry with multi-solvent extraction identifies metabolic differences between left and right blastomeres in the 8-cell frog (Xenopus) embryo

“…Additionally, single-cell MS can be performed under atmospheric-pressure conditions. For example, lipid and fatty acid changes were monitored in bovine 28 , porcine 29 , and mouse 30 oocytes and preimplantation embryos by desorption electrospray ionization as well as Xenopus eggs by laser ablation electrospray ionization 31 . Laser desorption ionization 32 and ablation 33, 34 found cellular heterogeneity and subcellular gradients, and direct-microsampling electrospray ionization (ESI) 35–37 helped to track drug metabolism in live cells.…”

Desorption Electrospray Ionization Mass Spectrometry Reveals Lipid Metabolism of Individual Oocytes and Embryos

“…Analysis of large biological datasets like this is facilitated by principal component analysis (PCA), commonly used for exploratory investigation of mass spectral datasets [30]. It allows compression of the data for in-depth characterization of biological samples and has been previously used to analyze DESI-MS data obtained from mouse preimplantation embryos [28]. …”