Chemotactic Sensitivity to Cyclic AMP and Suppression of the Chemotactic Response by Ammonia in Post-Vegetative Cells of Dictyostelium discoideum
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Growth and morphogenesis observed in the multicellular aggregates of the slime mold Dictyostelium discoideum exhibit many coordinated cell rearrangements that often parallel embryonic development of higher life forms. The development of D. discoideumnulls chemotactic apparatus potentially provide insights into how one such process changes as the organism matures. This study measured sensitivity to cyclic AMP, a chemoattractant that plays a significant role in the organization of unicellular Dictyostelium into multicellular aggregates, comparing results to more "advanced" stages in its life cycle. To measure the chemotactic response of post-vegetative cells, Dictyostelium response drops were placed 5 mm away from cyclic AMP source drops of varying concentration, and the distance Dictyostelium traveled was measured. After the minimum cyclic AMP concentration required to elicit a chemotactic response was determined to be between 2x10-7 M and 1x10-6 M, trials testing the lowest concentrations of ammonium chloride that suppressed chemotaxis at the determined cyclic AMP threshold were conducted. The range of ammonium chloride inhibiting chemotaxis was measured to be between 2.5x10-4 M and 4x10-4 M, identical to previously established values for prespore cells of the Dictyostelium slug.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2008
- F&M Theses Collection