# The role of a previously undiscovered sensory cilium in the model neural circuit that controls C. elegans egg laying

> **NIH NIH F31** · YALE UNIVERSITY · 2021 · $30,896

## Abstract

Project summary
Neural circuits are groups of neurons that respond to stimuli and signal to each other to form functional units of
the brain. When compromised, they are thought to cause brain disorders such as anxiety and depression.
However, it remains difficult to understand how abnormalities in neural circuits arise because we have yet to
understand how all the cells in any neural circuit interact normally. Due to its simple anatomy and easily-read
output, the C. elegans egg-laying circuit is intensively studied as a model for neural circuits. Even so, the egg-
laying circuit shows phenomena that cannot be explained, such as coordination between egg-laying and
locomotion behaviors, that suggest the circuit may have components that currently remain unknown. I have
discovered what may be a previously unrecognized neuron of the egg-laying system, and here I describe my
plans to utilize the many advantages this model circuit to characterize the functional role of this neuron in the
circuit. I initially discovered new neural structures lying immediately over the egg-laying system by examining
multiple transgenic strains that express fluorescent proteins in various subsets of C. elegans neurons. After
creating a GFP reporter transgene that labels only the cells that create these structures, I successfully
identified the structures to be branches off of the main processes of the two "PVP" neurons, whose functions
have not yet been determined. I used confocal microscopy to find that (a) the branches terminate in winged-
shaped sensory cilia; (b) the cilia develop concurrently as the rest of the egg-laying circuit differentiates; (c) the
PVP cilia are specific to hermaphrodites, and are not present in males (which lack an egg-laying circuit); and
(d) the PVP cilium vary in morphology and position from animal to animal. Furthermore, by expressing a
histamine-gated chloride channel specifically in PVP, I inhibited PVP activity in adult animals and observed
resulting changes in locomotion behavior, including increased reversals and decreased forward speed. This,
confirms a functional role for PVPs in controlling locomotion that had been hinted at by earlier studies. My
project tests the hypothesis that PVP uses its cilium to sense function of the egg-laying circuit and coordinates
locomotion with egg laying. To investigate this hypothesis, in Aim 1 I will visualize PVP in conjunction with
markers of other structures in the egg-laying anatomy to better understand the PVP cilium's position and
morphology in relation to the egg-laying circuit. In Aim 2, I will inhibit PVP activity and determine if and how
PVP functionally affects egg-laying and locomotion behaviors using a battery of behavioral assays. Lastly, in
Aim 3 I will express a calcium-sensitive fluorescent reporter in PVP and observe when PVP is active in freely-
behaving animals and moreover, using PVP-specific RNAi to disrupt the structure and function of PVP cilia,
determine if the PVP cilia are ...

## Key facts

- **NIH application ID:** 10124995
- **Project number:** 5F31NS115315-02
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Nakeirah Tashiara Mathews Christie
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $30,896
- **Award type:** 5
- **Project period:** 2020-04-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10124995

## Citation

> US National Institutes of Health, RePORTER application 10124995, The role of a previously undiscovered sensory cilium in the model neural circuit that controls C. elegans egg laying (5F31NS115315-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10124995. Licensed CC0.

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