# Elucidating Molecular Mechanisms Underlying Cooperation in Animal-Bacterial Symbioses

> **NIH NIH R35** · MICHIGAN STATE UNIVERSITY · 2024 · $375,400

## Abstract

PROJECT SUMMARY
Most, if not all, animals form beneficial symbioses with bacteria and live in contact with these
microbes for the majority of their lives. Understanding the mechanisms by which animals
associate with their symbionts is important to human health as we maintain consortia of
benefical bacteria at multiple body sites such as the gut and skin. While both partners ultimately
benefit from mutualistic interactions, hosts and symbionts both need to maintain mechanisms by
which they can ensure cooperation by their partner, also called “sanctioning”. While sanctioning
of symbionts is a widespread phenomenon, it can be difficult to study due to the large number
and diversity of microbial species present in many interactions and the accessibility of symbiotic
interfaces within the host.
The proposed work will determine the molecular determinants of sanctioning in two different
model systems: The Hawaiian Bobtail Squid Euprymna scolopes and its symbiont Vibrio
fischeri, and the skin microbiome of the newt Taricha granulosa. Both of these associations are
defensive mutualisms where the symbiont provides a product to the host that enables the host
to escape predation. We will leverage the tractability and accessibility of these systems, as well
as techniques that we have already developed, to answer crucial questions pertaining to
sanctioning. First, we will determine how the host detects symbiotic currency, the first step in
some sanctioning efforts, through candidate gene and unbiased approaches. Second, we will
define the mechanisms by which hosts sanction symbionts by determining which cells and
molecules lead to sanctioning and how they influence bacterial symbionts.
Overall, this work will determine the molecular mechanisms that allow animal hosts to ensure
the production of valuable symbiotic currency by their symbionts, filling a major gap in our
understanding of how mutualistic associations are maintained over the life of an animal.

## Key facts

- **NIH application ID:** 10900676
- **Project number:** 5R35GM150478-02
- **Recipient organization:** MICHIGAN STATE UNIVERSITY
- **Principal Investigator:** Elizabeth A. Heath-Heckman
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $375,400
- **Award type:** 5
- **Project period:** 2023-08-08 → 2028-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10900676

## Citation

> US National Institutes of Health, RePORTER application 10900676, Elucidating Molecular Mechanisms Underlying Cooperation in Animal-Bacterial Symbioses (5R35GM150478-02). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10900676. Licensed CC0.

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