Insight into glycan diversity and evolutionary lineage based on comparative Avio-N-glycomics and sialic acid analysis of 88 egg whites of Galloanserae

A large set of glycome information was obtained from egg white proteins of 88 samples from Galloanserae (63 Anseriformes and 25 Galliformes). The data were obtained on whole N-glycan structures and types of sialic acids of these egg whites by glycoblotting-based high-throughput and quantitative glycomics. The results revealed clear trends and complexity patterns as well as diversity among taxonomic groups. It is well-known that chicken, a representative domesticated poultry involved in Galliformes, can become an influenza host. However, our data demonstrate that duck, wild goose, and swan of Anseriformes are representative migratory birds that are known as natural hosts of the influenza virus. Hierarchical clustering analysis of the expression pattern of N-glycome (total of 61 N-glycan peaks) revealed that the members of Galloanserae can be classified into two major groups and five submajor clusters (clusters 1-5) on the basis of simple m/z values obtained by MALDI-TOF MS. It is clear that expression patterns of N-glycomes in the five clusters are influenced significantly by the features such as the body size of the birds, rather than by the difference of the family. On the other hand, quantitative analysis showed that the total amounts of sialic acids in egg whites of Galliformes were distinctly larger than those of Anseriformes. However, it was also revealed in Anseriformes that Neu5Gc and KDN, in addition to common Neu5Ac, were expressed significantly in both N- and O-glycans of glycoproteins and glycosphingolipids, suggesting the influence of their lifestyles and diet. This is the first report that KDN exists in egg white. These results and the environmental factors are discussed preliminarily with respect to their evolutionary lineage.