Project description:Bowman-Birk Inhibitor (BBI) has both insecticidal and anti-cancerous properties. It has been hypothesized that dietary BBI slows insect growth by inhibiting the catalytic activity of digestive enzymes trypsins and chyomotrypsins, resulting in the midgut having reduced access to amino acids needed for growth. In mammals, BBI was hypothesized to influence cellular energy metabolism. Thus, we tested the hypothesis that dietary BBI also impacts energy-associated pathways in the midgut of Drosophila melanogaster. We investigated the impact of dietary BBI on the following parameters in the midguts of third-instar Drosophila larvae: (i) cellular metabolites, (ii) global transcriptome response, (iii) putative transcription factor binding sites (TFBSs) associated with the differentially expressed transcripts, and (iv) epithelial cellular structure. Dietary BBI caused: (i) a reduction of cellular DHAP, glucose, and succinate; and, (ii) increased Fructuse-6-phosphate; (ii) differential expression of genes associated with the glucose and fatty acid utilization; and, (iii) a shortening of midgut epithelial microvilli, a phenomenon previously associated with glucose starvation. Additionally, fifty seven percent of the putative TFBSs associated with the differentially expressed transcripts have previously been associated with glucose and insulin activities in mammalian studies. Collectively these results support the hypothesis that dietary BBI influences energy utilization in the Drosophila midgut. Keywords: stress response
Project description:Survival of insects on a substrate containing toxic substances such as plant secondary metabolites or insecticides is dependent on the metabolism or excretion of those xenobiotics. The primary sites of xenobiotic metabolism are the midgut, Malpighian tubules and fat body. In general, these organs are treated as single tissues by online databases, but several studies have shown that gene expression within subsections of the midgut is compartmentalized. In this article, RNA sequencing analysis was used to investigate whole-genome expression in subsections of the third-instar larval midgut. The results support functional diversification in subsections of the midgut. Analysis of the expression of gene families that are implicated in the metabolism of xenobiotics suggests that metabolism may not be uniform along the midgut. These data provide a starting point for investigating gene expression and xenobiotic metabolism in the larval midgut.