Developmental and hormone-induced changes in chicken intestinal disaccharidases

Abstract

Changes in specific activity levels, on tissue wet wt. and protein bases, were determined for avian jejunal disaccharidases in the developing chick embryo and chick. Maltase (α- d-glucoside glucohydrolase, EC 3.2.1.20) and sucrase (β- d-fructofuranoside fructohydrolase, EC 3.2.1.26) showed similar but not identical patterns of change, with marked increases of specific activity on either basis about the time of hatching, while lactase (β- d-galactoside galactohydrolase, EC 3.2.1.23) showed no increase on a protein basis. The pH-activity profile of chick jejunal maltase was significantly different from that of the embryo enzyme; no such difference was observed for sucrase or lactase. The specific activity levels of all three enzymes showed significant but quantitatively different elevations in late embryos obtained from eggs injected with hydrocortisone at 14 days of development, compared to levels in control embryos of the same developmental stages. Jejunal lactase levels were also increased modestly by hydrocortisone administration to newly hatched chicks. No significant changes in disaccharidase levels were produced by disaccharide administration to embryos or by high disaccharide diets in chicks.