Sialylation of intestinal microvillar membranes in newborn, sucking and weaned pigs.

Affinity cytochemistry and biochemistry revealed distinctive temporal changes in the expression of sialylated and compositionally related membrane glycoconjugates in the pig small intestine between birth and weaning. The expression of membrane NeuAc alpha 2,6 moieties, recognized by Sambucus nigra agglutinin-1, was high in newborn pigs, declined slightly during sucking and was very low in weaned animals. Conversely, the expression of membrane NeuAc alpha 2.3 moieties, recognized by Maackia amurensis agglutinin-2, was low at birth but higher in sucking and weaned animals. Histoblood group O- and A-antigen expression was first detected in a minority of sucking pigs, but was evident in all weaned pigs examined. Lactase glycoforms were isolated from solubilized microvillar membranes of newborn and weaned pigs. The newborn (predominantly alpha 2,6-sialylated) and weaned (predominantly alpha 1,2-fucosylated) glycoforms exhibited similar specific activity, indicating that postnatal lactase decline in the pig intestine is unrelated to temporal changes in membrane sialylation and fucosylation.