The Drosophila wing disc is divided along the proximaldistal axis into regions giving rise to the body wall (proximal), wing hinge(central) and wing blade (distal). We applied DNA microarray analysis to discover genes with potential roles in the development of these regions. We identified a set of 94 transcripts enriched (two fold or greater) in the body wall and 56 transcripts enriched in the wing/hinge region. Transcripts that are known to have highly restricted expression patterns, such aspannier, twist and Bar-H1 (body wall) and knot,nubbin and Distal-less (wing/hinge), showed strong differential expression on the arrays. In situ hybridization for 50 previously uncharacterized genes similarly revealed that transcript enrichment identified by the array analysis was consistent with the observed spatial expression. There was a broad spectrum of patterns, in some cases suggesting that the genes could be targets of known signaling pathways. We show that three of these genes respond to wingless signaling. We also discovered genes likely to play specific roles in tracheal and myoblast cell types, as these cells are part of the body wall fragment. In summary, the identification of genes with restricted expression patterns using whole genome profiling suggests that many genes with potential roles in wing disc development remain to be characterized.

The highly conserved epidermal growth factor receptor (Egfr) pathway is required in all animals for normal development and homeostasis; consequently, aberrant Egfr signaling is implicated in a number of diseases. Genetic analysis of Drosophila melanogaster Egfr has contributed significantly to understanding this conserved pathway and led to the discovery of new components and targets. Here we used microarray analysis of third instar wing discs, in which Egfr signaling was perturbed, to identify new Egfrresponsive genes. Upregulated transcripts included five known targets, suggesting the approach was valid. We investigated the function of 29 previously uncharacterized genes, which had pronounced responses. The Egfr pathway is important for wing-vein patterning and using reverse genetic analysis we identified five genes that showed venation defects. Three of these genes are expressed in vein primordia and all showed transcriptional changes in response to altered Egfr activity consistent with being targets of the pathway. Genetic interactions with Egfr further linked two of the genes, Sulfated (Sulf1), an endosulfatase gene, and CG4096, an A Disintegrin And Metalloproteinase with ThromboSpondin motifs (ADAMTS) gene, to the pathway. Sulf1 showed a strong genetic interaction with the neuregulin-like ligand vein (vn) and may influence binding of Vn to heparan-sulfated proteoglycans (HSPGs). How Drosophila Egfr activity is modulated by CG4096 is unknown, but interestingly vertebrate EGF ligands are regulated by a related ADAMTS protein. We suggest Sulf1 and CG4096 are negative feedback regulators of Egfr signaling that function in the extracellular space to influence ligand activity.

Education research shows many benefits of involving students in service learning. However, designing service-learning projects for science courses such as microbiology can be problematic. This article describes an effective, easily adapted project design that gets allied-health microbiology students to apply classroom knowledge towards educating the general public about infectious diseases.

Differential gene expression is the major mechanism underlying the development of specific body regions. Here we assessed the role of genes differentially expressed in the Drosophila wing imaginal disc, which gives rise to two distinct adult structures: the body wall and the wing. Reverse genetics was used to test the function of uncharacterized genes first identified in a microarray screen as having high levels of expression in the presumptive wing. Such genes could participate in elaborating the specific morphological characteristics of the wing. The activity of the genes was modulated using misexpression and RNAi-mediated silencing. Misexpression of eight of nine genes tested caused phenotypes. Of 12 genes tested, 10 showed effective silencing with RNAi transgenes, but only 3 of these had resulting phenotypes. The wing phenotypes resulting from RNAi suggest that CG8780 is involved in patterning the veins in the proximal region of the wing blade and that CG17278 and CG30069 are required for adhesion of wing surfaces. Venation and apposition of the wing surfaces are processes specific to wing development providing a correlation between the expression and function of these genes. The results show that a combination of expression profiling and tissue-specific gene silencing has the potential to identify new genes involved in wing development and hence to contribute to our understanding of this process. However, there are both technical and biological limitations to this approach, including the efficacy of RNAi and the role that gene redundancy may play in masking phenotypes.