Use of a novel epithelial assay to screen for polyamine transport in Drosophila melanogaster


Polyamines are polycationic molecules that perform many functions essential to cell growth and proliferation. These compounds can be synthesized inside the cell or taken into the cell exogenously. Many tumor types have been shown to contain elevated polyamine levels and an activated polyamine transporter (PAT) for importing exogenous polyamines. Thus, the PAT represents a potential target for anti-cancer strategies. To date, the mechanism of polyamine uptake into cells of multicellular eukaryotes is poorly understood, primarily because the only PAT proteins that have been identified are in the unicellular organisms Escherichia coli, Saccharomyces cerevisiae, and the protozoan parasite Leishmania major. In order to identify a PAT, in a higher eukaryote, a novel Drosophila imaginal disc epithelial development assay was employed. In this assay, development of the imaginal disc epithelium is inhibited by polyamine-toxin conjugates with results (PAT selectivity and toxicity) similar to those shown in vertebrate Chinese Hamster Ovary (CHO) cells. Using the Gene Ontogeny database at Fly Base, 39 candidates for a Drosophila PAT were identified based on their putative function as cation transport proteins or polyamine transport proteins. Twenty of the candidate genes were selected for further analysis based on their expression in imaginal discs and availability of strains carrying mutations in these genes. Imaginal discs dissected from the candidate mutant strains were tested for defects in polyamine uptake following exposure to polyamine-toxin conjugates. Mutations in two genes, Orct2 and CG9413, conferred increased resistance to the polyamine-toxin in the epithelial assay, as would be expected for imaginal disc cells defective in polyamine transport. Therefore, these two genes represent candidates for the polyamine transporter in a multicellular eukaryote


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Thesis Completion





Von Kalm, Laurence


Bachelor of Science (B.S.)


Burnett College of Biomedical Sciences

Degree Program

Molecular Biology and Microbiology


Biomedical Sciences -- Dissertations, Academic;Dissertations, Academic -- Biomedical Sciences







Access Status

Open Access

Length of Campus-only Access


Document Type

Honors in the Major Thesis

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