Role of specific activators of intestinal amino acid transport in Bombyx mori larval growth and nutrition

Nutrient absorption and its modulation are critical for animal growth. In, this paper, we demonstrate that leucine methyl ester (Leu-OMe) can greatly increase the activity of the transport system responsible for the absorptio n of most essential amino acids in the larval, midgut of the silkworm Bomby x mori. We investigated leucine uptake activation by Leu-OMe in brush borde r membrane vesicles, and in the apical. membrane of epithelial cells: in th e midgut incubated in vitro. Moreover, the addition of this strong. activat or of amino acid absorption to diet significantly affected larval growth. S ilkworms fed on artificial, diet supplemented with Leu-OMe reached maximum body weight 12-18: h before control larvae, and produced cocoon shells up t o 20% heavier than those of controls. The activation of amino acid, absorpt ion plays an essential role in larval development so that larval growth and cocoon production similar to controls reared on an artificial diet with 25 % of dry mulberry leaf powder were observed in silkworms fed on an artifici al diet with only 5% of mulberry powder. (C) 2001 Wiley-Liss, Inc.