# Genetically engineered ants to label and study neurons involved in social behavior

> **NIH NIH R21** · UNIVERSITY OF PENNSYLVANIA · 2021 · $243,563

## Abstract

ABSTRACT
The goal of this proposal is to generate genetic reporter lines for neuronal circuits that regulate social
behavior in Harpegnathos saltator ants and to utilize these lines to visualize brain remodeling as adult workers
reprogram themselves to behave as ant queens.
Social insects are an emerging model system to study the epigenetic regulation of brain function and behavior
because the same genome specifies alternative behavioral states in different castes. Whether and how brains
of workers and queens are differently wired to implement distinct sets of caste-specific behaviors is not known.
In Harpegnathos ants, adult workers can become queens via a caste transition that involves dramatic
phenotypic changes in reproduction, physiology, and behavior. This feature of Harpegnathos ants allows for
easy propagation of engineered alleles, as any individual can become reproductive.
The ability of adult Harpegnathos workers to become queens offers unique opportunities for the mechanistic
dissection of adult brain plasticity. Single-cell RNA-seq analyses revealed major changes in cellular
composition affecting both neurons and glia, indicating that a structural remodeling of the brain accompanies
the caste transition. The molecular signals that direct this brain remodeling remain unknown.
We previously showed that the neuropeptide corazonin stimulates hunting, a worker-specific behavior, and
is downregulated as workers become queens. We have since obtained new preliminary evidence that the ant
homolog of human vasopressin is expressed in a caste-specific manner and likely also regulates a subset
of social behaviors in Harpegnathos ants. We hypothesize that signaling by these neuropeptides directs brain
remodeling events that underpin the switch in social behaviors during the caste transitions.
In Aim 1, we will utilize a transgenic approach to label corazonin- and vasopressin-producing neurons and
their projection with membrane-bound GFP and to observe their remodeling during the natural caste transition.
In Aim 2, we will utilize CRISPR/Cas9 to generate knock-in driver and reporter lines to label neurons that
respond to corazonin or vasopressin and visualize their plasticity at the cellular and synaptic level in response
to the neuropeptides.
These experiments will reveal crucial information on adult brain plasticity in Harpegnathos ants and provide
sophisticated genetic tools for the further dissection of the epigenetic regulation of social behavior in these
ants. Given that corazonin and vasopressin have mammalian counterparts, our results are expected to have a
broad impact on our understanding of how neuropeptides regulate brain plasticity and social behavior.

## Key facts

- **NIH application ID:** 10218394
- **Project number:** 1R21MH123841-01A1
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Roberto Bonasio
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $243,563
- **Award type:** 1
- **Project period:** 2021-04-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10218394

## Citation

> US National Institutes of Health, RePORTER application 10218394, Genetically engineered ants to label and study neurons involved in social behavior (1R21MH123841-01A1). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10218394. Licensed CC0.

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