Meeting Abstract
It has already been shown that house sparrow nestlings are capable of modulating their intestinal digestive enzyme activity to match changes in substrate levels in their diet. However, it is not known how quickly nestlings can adjust to new diets with different substrate compositions. Wild house sparrows are primarily fed a low-carbohydrate insect diet during the first few days post-hatch and are gradually transitioned to a high-carbohydrate seed diet that they eat as adults, and it is possible that sometimes rapid diet switches are necessary in the wild in order to ensure survival. In the current study, 3-day-old nestlings were captured and fed a low-carbohydrate diet for three days before being switched to a high carbohydrate diet. Intestinal tissue was then harvested at 24, 48, and 72 hours after the diet switch and analyzed for enzyme activity per gram tissue. We found that activities of the intestinal carbohydrases maltase-glucoamylase and sucrase-isomaltase approximately doubled within 24 hours of the switch to high carbohydrate, and activity did not significantly increase in nestlings with further time on the new diet. Intestinal aminopeptidase-N activity significantly decreased once the animals were switched to the higher carbohydrate, lower protein diet within 24-48 hours. Future studies will determine the time course for reversed trends when nestlings are switched from initially high-carbohydrate diet to low-carbohydrate diet and will also test for underlying changes in intestinal enzyme mRNA. Supported by NSF IOS-1354893 to WHK.
