Placental glycosylation in peccary species and its relation to that of swine and dromedary

Abstract

Comparison has been made between glycans at the fetomaternal interface of two Tayassu species (New World peccaries or wild pigs) and those of swine (true pigs) and dromedary, which have similar epitheliochorial placentae. Plastic sections of near-term fetomaternal interface from Tayassu tajacu (120 days gestation) and Tayassu pecari (140 days gestation) were stained with 20 lectins and compared with those of swine (109 days) and dromedary (375 days). Both Tayassu species showed similar staining characteristics, which differed only slightly from those of the swine. Most differences were quantitative rather than qualitative, except for binding of Arachis hypogaea lectin to terminal β-galactose which was absent in swine uterine epithelium though present in both Tayassu species, and binding of Sambucus nigra lectin to sialic acid which was absent in swine epithelium and trophoblast though present in Tayassu. Glycosylation of the dromedary fetomaternal interface showed, in contrast, significant differences compared to Tayassu and swine, particularly regarding fucosyl, sialyl and terminal galactosyl residues. Despite a divergence of between 33 million and 37 million years between true pigs and peccaries, glycosylation of the fetomaternal interface has remained similar, with most of the observed changes affecting terminal structures. The dromedary has an epitheliochorial placenta with a similar architecture, but different glycan expression, suggesting modification of glycosyl transferases with evolution. These data contain clues to changes of glycosyl transferase activity that accompany speciation.