# Live imaging of neuron circuit assembly in Drosophila olfactory system

> **NIH NIH K99** · STANFORD UNIVERSITY · 2021 · $127,683

## Abstract

Project Summary/Abstract
Proper functions of the brain rely on specific neuron connections and their assembly into functional circuit.
However, many detailed mechanisms of the dynamic process of circuit assembly are unclear due to difficulty to
visualize it in live brains. Employing an explant system based live imaging, here I propose to investigate the
cell biology underpinnings of neural circuit assembly using the Drosophila olfactory system.
 In the Drosophila olfactory circuit, 50 classes of olfactory receptor neurons (ORNs) send their axons to
specific glomeruli in the antennal lobe (AL), where they make one-to-one connections with corresponding
second-order olfactory projection neurons (PNs). This provides an excellent system to study how neurons form
specific connections during circuit assembly. Recently I developed an explant system that allows me to use live
imaging to reveal the dynamic process of olfactory circuit assembly. Here I propose to use this explant to: 1.
image how single ORN axon targets its glomerulus; 2. explore how ORN-ORN or ORN-PN interaction
regulates targeting through surgical cutting one antennal nerve; 3. characterize the mistargeting phenotype in
Drosophila latrophilin mutant using live imaging (Aim 1 and part of Aim 3, K99 training phase).
 The K99 training phase studies mostly focus on defining the coarse targeting using two-photon
microscope based long term imaging. To further pursue detailed mechanisms underlying interesting behaviors
of the ORN axons, advanced imaging method allowing higher temporal and spatial resolution is required.
Therefore I propose to perform high speed two color imaging using adaptive optical lattice lightsheet
microscope. Combined with genetic tool for cytoskeleton labeling and manipulation, I aim to understand cell
biology mechanism of crucial steps in ORN axon targeting. This study will be in collaboration with Dr. Eric
Betzig at Janelia Research Campus. We have already got promising results from pilot experiments. I will also
pursue potential Latrophilin-Ten-a mediated axon-axon or axon-dendrite repulsion using live imaging (Aim 2
and part of Aim 3, R00 training phase). In general the R00 training phase studies will deal with more
complex situation in both imaging strategy and biological context.
 My mentoring team consists of Dr. Liqun Luo (mentor), a world-renowned neuroscientist, and Drs. Kang
Shen (co-mentor), an experienced cell biologist and developmental neurobiologist and Eric Betzig
(collaborator), Nobel laureate and world-renowned microscopist, as well as Dr. Michael Lin (consultant), an
expert on developing genetic imaging tools. With their guidance, I believe that I will gain extensive training in
my transition to be an independent PI.

## Key facts

- **NIH application ID:** 10225345
- **Project number:** 5K99DC018830-02
- **Recipient organization:** STANFORD UNIVERSITY
- **Principal Investigator:** Tongchao Li
- **Activity code:** K99 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $127,683
- **Award type:** 5
- **Project period:** 2020-08-01 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10225345

## Citation

> US National Institutes of Health, RePORTER application 10225345, Live imaging of neuron circuit assembly in Drosophila olfactory system (5K99DC018830-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10225345. Licensed CC0.

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