Meeting Abstract
Dietary flexibility in digestive enzyme activity is widespread in vertebrates, but mechanisms are poorly understood. Fragmentary evidence indicates that laboratory rats modulate intestinal α-glucosidase (AG) activity mainly by relying on rapid increase in enzyme transcription followed by translation and translocation to the intestineʼs apical, brush border membrane (BBM). We performed the first unified study of this overall process, relying on activity, transcriptomic and proteomic data from the same animals. We used as our model nestling house sparrows (Passer domesticus), which increase their intestinal AG activity as they switch naturally from low starch insect diet to higher starch seed diet. Twenty-four hours after a switch to a high starch diet, intestinal AG activity and mRNA were increased. The protein sucrase-isomaltase (SI), which is responsible for all maltase and sucrase activity, was the only hydrolase increased in the BBM, and its abundance and activity were positively correlated. This is the first demonstration that birds may rely on rapid increase in enzyme abundance when adjusting to high starch diet.
