Term of Award
Master of Science in Biology (M.S.)
Document Type and Release Option
Thesis (open access)
Copyright Statement / License for Reuse
This work is licensed under a Creative Commons Attribution 4.0 License.
Department of Biology
Committee Member 1
Committee Member 2
Fleas (Order Siphonaptera) are opportunistic blood feeders that parasitize a wide variety of mammals and birds. They also transmit bacterial pathogens that cause diseases in humans (e.g., murine typhus, flea-borne spotted fever, cat scratch disease, and plague). Because they acquire infectious pathogens while blood feeding, the flea gut is considered to be the initial site of infection. While immune responses have been well documented in other disease vectors, few studies have identified the immune mechanisms involved in defense of the flea gut. In other hematophagous insects, the synthesis of reactive oxygen species (ROS) is the immediate immune defense mechanism against foreign microbes. To investigate the role of ROS in flea gut immunity, cat fleas (Ctenocephalides felis) were orally infected with the model insect pathogen Serratia marcescens. Specifically, fleas were treated with an antioxidant to reduce the amount of microbicidal ROS before infection, and then S. marcescens infection loads were measured. Additionally, we measured hydrogen peroxide (ROS) levels, and the relative quantity of mRNA for select genes associated with DUOX, a surface protein of epithelial cells responsible for ROS production. Four experimental groups were examined: (1) S. marcescens-infected fleas; (2) fleas fed an antioxidant; (3) fleas fed an antioxidant and then infected with S. marcescens, and (4) fleas fed on untreated blood (control). Overall, these results show that ROS levels in the gut increase in response to infection, and the signaling pathway for DUOX activation is tightly regulated. This study provides evidence that ROS is a key mechanism for early gut defense in cat fleas.
Maness, Ryne W., "Transcriptional Regulation of DUOX-Dependent Reactive Oxygen Species Production Against Bacterial Infection in the Gut of Cat Fleas (Ctenocephalides felis)." (2021). Electronic Theses and Dissertations. 2215.
Research Data and Supplementary Material