Honors College Theses

Publication Date

4-29-2024

Major

Biology (B.S.B.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Lisa Brown

Abstract

Cat fleas (Ctenocephalides felis) are a blood-feeding ectoparasitic insect and a common domestic pest found throughout the world. Because of their reliance on host blood, fleas are exposed to blood-borne pathogens; however, the flea gut lumen is a hostile environment for microbial colonization. For example, the gut epithelia differentially express immune genes in response to feeding. In the present study, we measured the antimicrobial activity of gut proteins from cat fleas at different days after feeding (2, 5, 7, and 14). Dissected flea guts were homogenized, passed through a syringe filter, and measured in a protein assay kit. Antimicrobial activity was assessed by incubating flea gut samples with the bacterial species Micrococcus luteus overnight in a microtiter plate, and then plating the samples on nutrient agar to compare bacterial growth. Our results shows that protein concentrations increase with feeding days, and this increase generally corresponds to a higher antimicrobial activity.

Thesis Summary

Although the lifespan of adult fleas is relatively short (about one month), age-dependent variations in the physiology of fleas have not been examined. In the present study, we aimed to determine whether the antimicrobial activity of flea gut contents decreases with age. Specifically, we determined the protein concentration from cat fleas at different days post blood feeding (2, 5, 7 and 14) using a protein assay kit and homogenized flea gut samples. Next, flea gut samples were incubated with the Gram-positive bacterium Micrococcus luteus overnight, after which bacterial growth was measured on nutrient agar plates. We found that protein concentrations in the flea gut increase with feeding days, but the strength of antimicrobial activity is dependent on flea age.

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