Meeting Abstract

24.5  Friday, Jan. 4  Diet-induced plasticity in intestinal maltase activity in nestling house sparrows during development KOHL, K.; BRZEK, P.; CAVIEDES-VIDAL, E.; KARASOV, W.H.*; University of Wisconsin, Madison; University of Wisconsin, Madison; Universidad Nacional de San Luis, Argentina; University of Wisconsin, Madison pbrzek2@wisc.edu

Previous studies in adult house sparrows (Passer domesticus) showed a lack of modulation of intestinal maltase activity (i.e. activity of maltase-glucoamylase and sucrase-isomaltase complexes) when birds were fed diets with contrasting starch contents (Comp Biochem Physiology [2000] 125:11-24). Nestling house sparrows are mainly insectivorous immediately after hatch but then shift to seeds. If they are also digestively inflexible, then maltase activity will be diet-independent during development. Nestlings were collected at 3 days of age and raised on an insect-like diet (59% casein, 20% corn oil, 0% starch) or a diet with 25% corn starch (replacing some casein). Rates of mass gain and development were diet-independent. Surprisingly, specific maltase activity increased significantly faster during development in nestlings fed +starch diet, compared with 0 starch diet, and was twice as high in the former group at time of fledging (12 days; P < 0.001). The change in maltase was specific, with no dietary difference in aminopeptidase-N activity. Thus, diet-induced plasticity in maltase activity, absent in adults, is now shown to be present in nestlings. Future studies must test whether the increase in maltase activity during development is (a) due to increments in both disaccharidase complexes and, (b) if it is irreversible or reversible reflecting, respectively, a developmental plasticity or a phenotypic flexibility that is lost later in life. Supported by NSF IOS-0615678 to W.H.K.