Oligosaccharides are involved in a host of cellular processes including recognition, growth, and adhesion. Its importance to human health encompasses areas as diverse as reproduction, infection, and cancer. Structural diversity and heterogeneity is responsible for the incredible versatility of oligosaccharides, but these characteristics make it difficult to do analysis. Nonetheless, significant progress in determining structures has been made aided recently by mass spectrometry. Structural elucidation, however, is still only one-step in understanding structure-function relationship. The determination of oligosaccharide diversity is the next important step, but it represents a formidable challenge. It requires the combination of structural elucidation, rapid identification and the quantitation of expression levels. In this research the diversity of oligosaccharides in the extracellular matrix of the egg of Xenopus laevis will be determined. The egg of Xenopus laevis is an important model for vertebrate reproduction. The extracellular matrix is involved in a number of functions including protection and sperm capacitation. It consists of the fertilization layer, the vitelline envelope, and three layers of egg jelly. All four layers are composed of glycoproteins. The egg jelly is highly glycosylated with 60% glycans by weight. The biological functions of the layers are largely known but the specific roles of the oligosaccharides are relatively unknown. Methods for characterizing oligosaccharide diversity will be developed to provide analytical tools for glycomics. These methods will employ primarily mass spectrometry and will be used to rapidly elucidate structures of unknown neutral and anionic components, identify known components, and quantitate their abundances. The diversity of oligosaccharides between individuals and between individual eggs will be determined. In the process, methods for the oligosaccharide analysis of single eggs will be developed. Large diversity is expected between individuals to conform to the theory of exogenous pressures as the driving force for diversity. However, oligosaccharide diversity between individual eggs will be small. As part of this project, the vitelline envelope, or the fertilization layer, will be analyzed for its oligosaccharide content. The vitelline envelope is analogous to the zona pellucida in mammals. This research will lay the foundation for the analysis of single mammalian eggs.
Showing the most recent 10 out of 102 publications
