title: Subcellular metabolite and lipid analysis of Xenopus laevis eggs by LAESI mass spectrometry.
abstract: Xenopus laevis eggs are used as a biological model system for studying fertilization and early embryonic development in vertebrates. Most methods used for their molecular analysis require elaborate sample preparation including separate protocols for the water soluble and lipid components. In this study, laser ablation electrospray ionization (LAESI), an ambient ionization technique, was used for direct mass spectrometric analysis of X. laevis eggs and early stage embryos up to five cleavage cycles. Single unfertilized and fertilized eggs, their animal and vegetal poles, and embryos through the 32-cell stage were analyzed. Fifty two small metabolite ions, including glutathione, GABA and amino acids, as well as numerous lipids including 14 fatty acids, 13 lysophosphatidylcholines, 36 phosphatidylcholines and 29 triacylglycerols were putatively identified. Additionally, some proteins, for example thymosin β4 (Xen), were also detected. On the subcellular level, the lipid profiles were found to differ between the animal and vegetal poles of the eggs. Radial profiling revealed profound compositional differences between the jelly coat vitelline/plasma membrane and egg cytoplasm. Changes in the metabolic profile of the egg following fertilization, e.g., the decline of polyamine content with the development of the embryo were observed using LAESI-MS. This approach enables the exploration of metabolic and lipid changes during the early stages of embryogenesis.
authors.affiliation: Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, D.C., United States of America.
authors.forename: Bindesh
authors.initials: B
authors.lastname: Shrestha
authors.affiliation: Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, D.C., United States of America.
authors.forename: Prabhakar
authors.initials: P
authors.lastname: Sripadi
authors.affiliation: Protea Biosciences, Morgantown, West Virginia, United States of America.
authors.forename: Brent R
authors.initials: BR
authors.lastname: Reschke
authors.affiliation: Protea Biosciences, Morgantown, West Virginia, United States of America.
authors.forename: Holly D
authors.initials: HD
authors.lastname: Henderson
authors.affiliation: Protea Biosciences, Morgantown, West Virginia, United States of America.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Powell
authors.affiliation: Department of Anatomy and Regenerative Biology, The George Washington University, Washington, D.C., United States of America.
authors.forename: Sally A
authors.initials: SA
authors.lastname: Moody
authors.affiliation: Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, D.C., United States of America.
authors.forename: Akos
authors.initials: A
authors.lastname: Vertes
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D047108:Embryonic Development; D005978:Glutathione / Q000032:analysis; D008055:Lipids / Q000032:analysis*; D010063:Ovum / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013347:Subcellular Fractions / Q000737:chemistry; D014982:Xenopus laevis; D005680:gamma-Aminobutyric Acid / Q000032:analysis
chemical_list: D000596:Amino Acids; D008055:Lipids; D005680:gamma-Aminobutyric Acid; D005978:Glutathione