Lipid profile of bovine oocytes and embryos by MALDI imaging

In the field of “single cell analysis”, many classical strategies like immunoflurescence and electron microscopy are the fundamental choices. However, these methodologies are time consuming and do not permit direct identification of specific molecular classes such as lipids. This study was conducted to determine a new mass spectrometry based analytical approach to bovine oocytes and embryos in vitro produced. Images and mass spectra were acquired in a MALDI-LTQ-XL instrument with imaging feature (Thermo Scientific, California, USA). It was equipped with a UV laser (Nd:YAG, 355 nm) at “minimum” focus. Imaging data were analyzed in quadruplicates using ImageQuest software (Thermo Scientific, California, USA). A new metabolomics based application uses Mass Spectrometry Imaging (MSI), efficient data processing and multivariate data analysis. Metabolic fingerprinting (MF) was applied to the analysis of bovine occytes and blastocysts. A semi quantitative strategy for sphingomyelin [SM (16:0) + Na]+ (m/z 725) and phosphatidylcholine [PC (32:0) + Na]+ (m/z 756) was developed, showing that lipid concentration was useful for selecting the best biomarkers. This information furthers our understanding of fertilization and pre implantation events during bovine embryo development.