Date of Award

2018

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dr. Christopher Sheil

Abstract

Batrachochytrium dendrobatidis (Bd) is one of the primary drivers of amphibian decline, and has spread rapidly on a global scale, but the mechanisms of Bd movement on small spatial scales are poorly understood and may play a role in transmission and infection. The flagellated zoospores of this fungus exhibit chemotaxis in response to single chemical cues, towards potential nutrient sources and away from metabolites of anti-fungal bacteria (AFB) present on amphibian skin. Levels of cutaneous AFB were manipulated on Eurycea bislineata hosts (either by bathing in a culture of the AFB Janthinobacterium lividum, or bathing in antibiotics) to test the effects of differences in cutaneous microbiota on the chemotaxis of Bd zoospores. Chemotaxis was measured using a hemocytometer grid to track average movement of zoospores for 45 minutes. A stochastic model was implemented based on observed magnitudes of chemotaxis to estimate probability of zoospores reaching a host as a function of distance from host. Differences in net chemotaxis between treatments was non-significant, and overall levels of mean net chemotaxis were low with high variance. The model suggests that chemotaxis is not a strong driver of probability of Bd zoospores reaching a host relative to simple distance from the host. Results do not support chemotaxis as a strong driver of Bd transmission, but chemotaxis may play a role in the development of Bd infections.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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