Data from: Systematic morphological and morphometric analysis of identified olfactory receptor neurons in Drosophila melanogaster
Data files
Jun 17, 2026 version files 56 GB
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Ir75c-GAL4_10XUAS-myc-APEX2-Orco.mrc
1.33 GB
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Or22a-GAL4__10XUAS-mCD8GFP-APEX2.mrc
1.60 GB
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Or47a-GAL4_10XUAS-myc-APEX2-Orco.mrc
9.87 GB
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Or47b-GAL4_10XUAS-myc-APEX2-Orco_Antenna_1.mrc
2.31 GB
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Or47b-GAL4_10XUAS-myc-APEX2-Orco_Antenna_2.mrc
8.72 GB
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Or56a-GAL4__10XUAS-myc-APEX2-Orco.mrc
8.92 GB
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Or7a-GAL4_10XUAS-myc-APEX2-Orco.mrc
16.55 GB
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Or88a-GAL4_10XUAS-myc-APEX2-Orco.mrc
6.71 GB
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README.md
3.77 KB
Abstract
The biophysical properties of sensory neurons are influenced by their morphometric and morphological features, whose precise measurements require high-quality volume electron microscopy (EM). However, systematic surveys of nanoscale characteristics for identified neurons are scarce. Here, we characterize the morphology of Drosophila olfactory receptor neurons (ORNs) across the majority of genetically identified sensory hairs. By analyzing serial block-face electron microscopy images of cryofixed antennal tissues, we compile an extensive morphometric data set based on 122 reconstructed 3D models for 33 of the 40 identified antennal ORN types. Additionally, we observe multiple novel features—including extracellular vacuoles within sensillum lumen, intricate dendritic branching, mitochondria enrichment in select ORNs, novel sensillum types, and empty sensilla containing no neurons—which raise new questions pertinent to cell biology and sensory neurobiology. Our systematic survey is critical for future investigations into how the size and shape of sensory neurons influence their responses, sensitivity, and circuit function.
Dataset DOI: 10.5061/dryad.zkh1893s6
Description of the data and file structure
Files and variables
File: Ir75c-GAL4_10XUAS-myc-APEX2-Orco.mrc
Description: Olfactory receptor neurons (ac3AII) with Ir75c receptors are labeled with APEX2 (dark stain).
File: Or47b-GAL4_10XUAS-myc-APEX2-Orco_Antenna_1.mrc
Description: One of two antennae where olfactory receptor neurons (at4A) with Or47b receptors are labeled with APEX2 (dark stain).
File: Or22a-GAL4__10XUAS-mCD8GFP-APEX2.mrc
Description: Olfactory receptor neurons (ab3A) with Or22a receptors are labeled with APEX2 (dark stain).
File: Or88a-GAL4_10XUAS-myc-APEX2-Orco.mrc
Description: Olfactory receptor neurons (at4C) with Or88a receptors are labeled with APEX2 (dark stain).
File: Or47b-GAL4_10XUAS-myc-APEX2-Orco_Antenna_2.mrc
Description: Second antenna, from a different individual, where olfactory receptor neurons (at4A) with Or47b receptors are labeled with APEX2 (dark stain).
File: Or56a-GAL4__10XUAS-myc-APEX2-Orco.mrc
Description: Olfactory receptor neurons (ab4B) with Or56a receptors are labeled with APEX2 (dark stain).
File: Or7a-GAL4_10XUAS-myc-APEX2-Orco.mrc
Description: Olfactory receptor neurons (ab4A) with Or7a receptors are labeled with APEX2 (dark stain).
File: Or47a-GAL4_10XUAS-myc-APEX2-Orco.mrc
Description: Olfactory receptor neurons (ab5B) with Or47a receptors are labeled with APEX2 (dark stain).
Code/software
Option 1. IMOD
We used the IMOD image processing package (https://bio3d.colorado.edu/imod/) to view these volumes. Download the appropriate version that is compatible with your operating system.
- Open the 3dmod application (the main viewing component of IMOD).
- In the startup window, click on "Select..." next to "Image file(s)" and browse to select the downloaded file.
- In case of low system memory: Before clicking "Open", look for the "Cache" option in that same startup window. Set the cache to 5 sections. This reduces the memory used so the file can load smoothly.
- Click Open.
Option 2: Fiji / ImageJ
If you do not have specialized electron microscopy software, you can open the file in Fiji using the Bio-Formats plugin to bypass memory limits. However, this option results in poorer image quality.
- Open Fiji/ImageJ.
- Go to File > Import > Bio-Formats.
- Select the .mrc file.
- In the Bio-Formats Import Options window that pops up, look under the "Dataset Organization" section.
- Check the box for "Use virtual stack".
- Click OK. The file will stream directly from your storage without overloading your computer's RAM.
System Requirements
Because these volumes are large, the primary bottleneck is system memory (RAM).
- Minimum RAM: 8 GB (but the file must be opened with cache turned on, as described above).
- Recommended RAM: 16 GB or higher to load the volume at full resolution.
- Operating System: Windows, macOS, or Linux.
Access information
Other publicly accessible locations of the data:
The Cell Image Library (http://www.cellimagelibrary.org/home) at the following accession numbers:
- CIL:54606 (Or22a/ab3A-labeled volume)
- CIL:54614 (Or7a/ab4A-labeled volume)
- CIL:54610 (Or56a/ab4B-labeled volume)
- CIL:54611 (Ir75c/ac3AII-labeled volume)
- CIL:54612 (Or47a/ab5B-labeled volume)
- CIL:54607 and CIL:54608 (Or47b/at4A-labeled volumes)
- CIL:54609 (Or88a/at4C-labeled volume)
The SBEM data sets were generated previously (Tsang et al., 2018; Zhang et al., 2019), except for the Or7a-labeled data set. Briefly, 6–8-day-old females were cold anesthetized and their antennae removed. Following isolation of the third antennal segment, the sample was subjected to high-pressure freezing, freeze-substitution, rehydration, DAB labeling, en bloc heavy metal staining, dehydration, and resin infiltration. The flies expressed membrane-tethered APEX2 (10xUAS-myc-APEX2-Orco or 10xUAS-mCD8GFP-APEX2) in select ORNs under the control of specific OrX- or Ir-X GAL4 drivers as described (Tsang et al., 2018; Zhang et al., 2019). Following microcomputed X-ray tomography to determine the position and proper orientation of the resin-embedded specimens, samples were mounted on aluminum pins with conductive silver epoxy and sputter coated with gold-palladium for SBEM imaging with a Gemini SEM (Zeiss) equipped with a 3View block-face unit or a Merlin SEM (Zeiss) equipped with a 3View2XP and OnPoint backscatter detector.
