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 me mbrane glycoconjugates in the pig small intestine between birth and we aning. The expression of membrane NeuAc alpha 2,6 moieties, recognized by Sambucus nigra agglutinin-1, was high in newborn pigs, declined sl ightly during sucking and was very low in weaned animals. Conversely, the expression of membrane NeuAc alpha 2,3 moieties, recognized by Maa ckia amurensis agglutinin-2, was low at birth but higher in sucking an d weaned animals. Histoblood group O- and A-antigen expression was fir st detected in a minority of sucking pigs, but was evident in all wean ed pigs examined. Lactase glycoforms were isolated from solubilized mi crovillar membranes of newborn and weaned pigs. The newborn (predomina ntly alpha 2,6-sialylated) and weaned (predominantly alpha 1,2-fucosyl ated) glycoforms exhibited similar specific activity, indicating that postnatal lactase decline in the pig intestine is unrelated to tempora l changes in membrane sialylation and fucosylation.