Structural determination of the oligosaccharides in the milk of a giant anteater (Myrmecophaga tridatyla)

There appears to be strong evidence supporting four major clades of placental mammals: (i) Afrotheria; (ii) Xenarthea; (iii) Euarchontoglires; and (iv) Laurasiathera. This is the first study in which the carbohydrates have been analyzed in the milks of Xenarthea. Our aim was to clarify whether the saccharides of giant anteater milk resemble those of other eutherian species, especially of the Asian elephant, which is one of the Afrotherea. We found that lactose is a dominant saccharide in this milk, as it is in that of most eutherians, and that the milk contains smaller amounts of oligosaccharides, whose structures were determined as Gal(alpha 1-3)Gal(beta 1-4)Glc (isoglobotriose), Neu5Ac(alpha 2-6)Gal(beta 1-4)Glc (6'-N-acetylneuraminyllactose), Neu5Gc(alpha 2-6)Gal(beta 1-4)Glc (6'-N-glycolylneuraminyllactose), Neu5Ac(alpha 2-6)Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc (LST c) and Neu5Gc(alpha 2-6)Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc. This pattern of milk carbohydrates is rather close to that of the milks of other eutherian species. It is notable that the milk contained oligosaccharides with Neu5Gc residues but no oligosaccharides containing alpha(2-3) linked Neu5Ac residues such as Neu5Ac(alpha 2-3)Gal(beta 1-4)Glc.