Date of Award

Summer 8-22-2026

Document Type

Dissertation

Degree Name

Ph.D. in Biological Sciences

Organizational Unit

College of Natural Science and Mathematics, Biological Sciences

First Advisor

Scott A. Nichols

Second Advisor

Erica Larson

Third Advisor

Schuyler van Engelenburg

Fourth Advisor

Jon Velotta

Copyright Statement / License for Reuse

All Rights Reserved
All Rights Reserved.

Keywords

Animal origins, Host-microbe, Multicellularity, Non-model immunity, Porifera, Symbiosis

Abstract

The most ancient eukaryotic immune defense mechanisms evolved in unicellular species. Multicellular eukaryotes, however, expanded these mechanisms to meet challenges unique to multicellular life, including barrier formation, long-distance cell signaling, and coordinated responses that eliminate microbial threats while minimizing damage to the host. As such, animal immune signaling pathways are exceptionally intricate and diverse. Though, most of what is understood about animal host–microbe interactions stems from a small handful of model systems. Here, I evaluate host–microbe interactions and innate immunity in sponges using the highly tractable freshwater sponge, Ephydatia muelleri. I report the discovery of an external host-derived matrix that physically separates host cells from environmental microbes, which reconciles longstanding inconsistencies between bulk-sequencing and ultrastructural surveys. I additionally take a reductionist approach in evaluating the E. muelleri response to immunogenic MAMPs (e.g., LPS), and show that these responses frequently converge on the ancient, highly conserved NF-κB transcriptional complex—a signaling hub that directly initiates inflammation in other animals. I further probe the innate immune responses of E. muelleri by developing a tractable infection model with the opportunistic pathogen, Legionella pneumophila. I show that L. pneumophila employs similar infection mechanisms in E. muelleri as for other eukaryotic hosts, including humans. This work highlights the importance of studying non-model animal immune systems to inform ancestral states and identify fundamental aspects of animal host–microbe interactions.

Copyright Date

8-2026

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Jacob S. Pawley

Provenance

Received from ProQuest

File Format

application/pdf

Language

English (eng)

Extent

203 pgs

File Size

162 MB

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