Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2010
Publication Date: 9/6/2010
Citation: Li, H., Sun, L., Omprakest, M., Xie, J., Wu, J., Schemerhorn, B.J., Pittendrigh, B. 2010. Bowman-Birk inhibitor affects pathways associated with energy metabolism in Drosophila melanogaster. Insect Molecular Biology. 13(3):303-313. Interpretive Summary: The insect digestive system is the first line of defense against anti-nutritional dietary factors. It is suggested that these dietary factors, created by plants are a defense strategy employed by the plant. These factors have been shown to slow insect development and increase larval mortality. While the regulatory mechanism of the plant for these factors is known, little is known about how the organisms exposed to them respond on a cellular level. An important group of these factors are the Bowman-Birk inhibitors (BBIs). They block important enzymes in the insect gut that are important for growth and development. Therapeutically, these types of defense factors have been used in humans for the treatment of HIV/AIDS and some cancers. In this study, we reported on the cellular and gross physical changes that occur to the midgut of Drosophila melanogaster larvae in response to dietary BBI.
Technical Abstract: Bowman-Birk inhibitor (BBI) is toxic when fed to certain insects, including the fruit fly, Drosophila melanogaster. Dietary BBI has been demonstrated to slow growth and increase insect mortality by inhibiting the digestive enzymes trypsin and chymotrypsin, resulting in a reduced supply of amino acids. In mammals, BBI influences cellular energy metabolism. Therefore, we tested the hypothesis that dietary BBI affects energy-associated pathways in the D. melanogaster midgut. Through microarray and metabolomic analyses, we show that dietary BBI affects energy utilization pathways in the midgut cells of D. melanogaster. In addition, ultrastructure studies indicate that microvilli are significantly shortened in BBI-fed larvae. These data provide further insights into the complex cellular response of insects to dietary protease inhibitors.