# Investigating mechanisms of specificity in a bioluminescent vertebrate-bacteria symbiosis

> **NIH NIH DP5** · CALIFORNIA ACADEMY OF SCIENCES · 2022 · $313,300

## Abstract

Project Summary
Investigating mechanisms of specificity in a vertebrate-bacteria symbiosis
Despite an increased awareness of the importance of the microbiome to human health and disease, relatively
little is known about the molecular mechanisms employed by symbiotic bacteria to stably colonize the gut, as
they are difficult to disentangle and experimentally study in isolation. There are several established model
systems used to explore specific pathways and processes underpinning symbiotic associations, however,
none represent a naturally evolved, binary symbiosis between a vertebrate host and a single bacterial
species. A major, long-term objective of this study is to establish the bioluminescent symbiosis
between a coral reef fish (Siphamia tubifer) and a luminous bacterium in the Vibrio family,
(Photobacterium mandapamensis) as a model association to define the mechanisms involved in
regulating specificity and colonization in a gut-associated symbiosis. The results of this project will
provide new insights on the evolution of stable interactions between vertebrate hosts and beneficial bacteria
and can be compared across model hosts to further define the universal principals underlying animal-microbe
associations.
The overall objective of this project is to investigate how the specificity of vertebrate-bacteria associations is
maintained from a broad evolutionary scale down to the molecular level by addressing the following research
aims: 1) Define the degree of specificity of the Siphamia–Photobacterium symbiosis, 2) Characterize
the infection dynamics and symbiont competition within a host light organ, and 3) Identify key
mechanisms involved in the establishment and persistence of the symbiosis. To do so, the specificity of
the symbiosis will first be broadly defined across all 23 species in the host fish genus, then across the broad
geographic distribution of a single host species, S tubifer. The specificity of the S. tubifer-P. mandapamensis
association will then be tested in culture to determine whether it is regulated by local environmental and
ecological factors or conserved at a more molecular level. Next, the intra-species symbiont diversity will be
experimentally tested to better understand strain competition and infection dynamics within a host. Finally,
the genetic mechanisms involved in regulating the symbiosis will be determined by comparing both host and
symbiont gene expression throughout the infection process. Overall this study will reveal the processes that
regulate the establishment and maintenance of specific associations between vertebrate hosts and beneficial
bacteria across multiple timescales, and in doing so, will provide the greater research community with a novel
binary vertebrate-bacteria model system with which to deepen our understanding of these vital interactions.

## Key facts

- **NIH application ID:** 10475833
- **Project number:** 5DP5OD026405-05
- **Recipient organization:** CALIFORNIA ACADEMY OF SCIENCES
- **Principal Investigator:** Alison Gould
- **Activity code:** DP5 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $313,300
- **Award type:** 5
- **Project period:** 2018-09-17 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10475833

## Citation

> US National Institutes of Health, RePORTER application 10475833, Investigating mechanisms of specificity in a bioluminescent vertebrate-bacteria symbiosis (5DP5OD026405-05). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10475833. Licensed CC0.

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