Electronic Thesis and Dissertation Repository


Master of Science




Dr. Brent J. Sinclair


Evidence of immune response enhancement after cold exposure suggests that cold activates the insect immune system. I investigated whether the immune response of Drosophila melanogaster is activated by cold exposure in the absence of pathogens. To explore if different kinds of cold affect the immune response differently, I included acute and chronic cold exposure. I cold-exposed flies, and then examined up-regulation of immune-related genes. In addition, I measured hemocyte concentration, phenoloxidase activity, and woundinduced melanization. Acute cold exposure increased hemocyte concentration and woundinduced melanization. Chronic cold did not change hemocyte concentration, phenoloxidase activity or melanization in flies. Acute and chronic cold did not affect the Toll pathway but up-regulated the JAK/STAT pathway. Acute, but not chronic cold activated the IMD pathway. I suggest a cold-immunity “cross-talk” in insects which can be affected differently by acute and chronic cold-exposure.