Date of Graduation

Summer 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Committee Chairperson

Greg Turner, PhD

Committee Member

Jessica Sowa, PhD

Committee Member

Benjamin Chambers, PhD

Committee Member

Eric Sweet, PhD

Committee Member

Jessica Sullivan-Brown, PhD

Abstract

The nematode Caenorhabditis elegans has emerged as a popular model system to investigate cell biology and host-pathogen interactions. Presently, C. elegans is studied as a natural host of intracellular pathogens such as microsporidia and Orsay virus along with extracellular bacterial and fungal pathogens. The use of C. elegans as a model in host-pathogen research is limited by the number of naturally occurring pathogens to the organism. Through a sampling project to identify new pathogens of C. elegans, we identified the fungus Mucor hiemalis as a pathogen of Caenorhabditis species. We observed the fungus in the intestinal lumen of wild-caught Caenorhabditis briggsae, and co-culturing the wild-caught species with infection reporter C. elegans confirmed infection by M. hiemalis. This study characterizes the fungal infection by M. hiemalis in Caenorhabditis nematodes. Fluorescence microscopy with fungal staining revealed the life cycle of M. hiemalis within multiple Caenorhabditis species at varying growth stages. We observed the killing of nematodes by M. hiemalis via intestinal perforation and assessed its’ host range through a series of lifespan assays. We investigated the food preference of C. elegans and determined that nematodes show a preference towards food that contains M. hiemalis sporangiospores. Lastly, we evaluated common C. elegans transcriptional immune responses and found that M. hiemalis induces two genes related to the Intracellular Pathogen Response Characterization of this fungal infection in Caenorhabditis nematodes will provide new insights into the biology of pathogenic fungi and host immune responses.

Final Version Confirmation

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