Meeting Abstract

P3.103  Tuesday, Jan. 6  Tracheal system expression of a matrix metalloproteinase varies throughout development in the tobacco hornworm, Manduca sexta VISHNUVARDHAN, Smitha*; GREENLEE, Kendra J.; North Dakota State University, Fargo; North Dakota State University, Fargo smitha.vishnuvardhan@ndsu.edu

Matrix metalloproteinases (MMPs) are a family of highly conserved, proteolytic enzymes found in most organisms. MMPs can degrade most types of extracellular matrix protein, making them important enzymes in the regulation of development. In fruitflies, MMPs are critical for metamorphosis and important for proper tracheal system development. During the molting process, MMPs cleave an adhesion molecule releasing the old exoskeleton from the new cuticle. In this study, we tested the hypothesis that MMPs play a role in tracheal system molting in Manduca sexta, the tobacco hornworm. Using zymography, we found active MMPs in isolated tracheae of 4th and 5th instar caterpillars. Tracheae of larvae from both the instars showed higher proteolytic activity at the end of the instar when compared to the beginning. In addition, proteolytic bands were also observed in samples of cuticle from late 5th instar larvae, further supporting the hypothesis that these enzymes are important for molting and metamorphosis. Recently, MMPs were identified in another lepidopteran, the waxmoth, Galleria mellonella. In the waxmoth, MMPs are hypothesized to be important for immune function, as they are upregulated upon exposure of hemocytes to bacterial lipopolysaccaride. If M. sexta MMPs are also important for immune function, then we should find MMP expression in immune-related organs such as fat body, hemolymph or hemocytes. However, we were unable to detect any proteolysis in the fat body, suggesting that MMPs present there may be inactive. Furthermore, MMP activity detected in hemolymph and hemocytes was found sporadically, indicating that MMP expression in these tissues may require induction by an immune response.