#cryo-et

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In the Ring

Bacteria divide and spread in minutes – over surfaces in hospitals and schools as well as inside our bodies, where 'friendly' bacteria compete with harmful bacteria like Escherichia coli (E. coli). This microscopic ‘Z-ring’, forms early in E. coli’s division (known as binary fission) constricting to 'pinch' the bacterial cell in two. Here researchers use cryo-electron tomography and computer rendering to picture the Z-ring in 3D – its torus shape ~100,000 times smaller than a ring doughnut. They find it’s made from concentric rings of short FtsZ protein filaments (coloured blue) held together by ZapD ‘crosslinkers’, a bit like garden wire through a festive wreath. Examining these structures in detail may be a step towards designing anti-bacterial chemicals to break the rings apart, halting division and preventing the spread of bacteria that may cause harmful infections.

Written by John Ankers

Image from work by Adrián Merino-Salomón and colleagues

Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany; Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in eLife, September 2025

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[currentsinbiology]

Better get a good look before they’re all gone...

Sperm Cell Tails Have Helix Structures, Could Help With Infertility

But this knowledge gap could shrink, with a new imaging technique called cryogenic electron tomography. Also known as cryo-ET, this innovative technology can zoom in on cells to capture them in 3-D. As first author on a paper employing this technique, Zabeo and his colleagues were able to study human sperm.

Their study, published in Scientific Reports, reveals a microscopic, left-handed helix structure at the tip of the sperm tail that has never been seen before. This finding could provide insights into why some seminal swimmers are more successful than others, and help to develop new drugs for infertility problems and contraception.

The tails of human sperm cells have left-handed helix shapes, scientists have found. PHOTOGRAPH BY DEAGOSTINI, GETTY

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Boundary Settings

Cells have organs too – with the fittingly diminutive title: organelles – each with a specific structure and function. Bounding the organelles are membranes composed of fatty sheets, a lipid bilayer. With cryo-ET (electron tomography), a high-resolution imaging technique to 'see' cells' inner features, this study reveals membrane thickness varies among organelles and provides a means to analyse how this affects their function

Read the published research article here

Video from work by Desislava Glushkova, Stefanie Böhm and Martin Beck

Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany

Video originally published with no restrictions – hence we publish as Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Journal of Cell Biology, November 2025

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Nano Society

Cryogenic electron tomography reveals in 3D the organisation and interactions between components of the reovirus (causing usually mild symptoms in humans) and organelles and molecular factors of the mammalian host cells it infects. Thus illuminating, as the authors describe, the 'molecular sociology' of the interplay.

Read the published research article here

Still from video from work by Xiaoyu Liu and Xian Xia, and colleagues

Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA

Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Nature Communications, December 2024

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ET Probe Hone

A new fast, interactive, user-friendly open-source tool for the annotation and analysis of cryo-electron tomography (cryo-ET) data called blik, a plug-in to the Python software image viewer napari

Read the published article here

Image from work by Lorenzo Gaifas and colleagues

Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in PLOS Biology, April 2024

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Processing Pipeline

Electron cryo-tomography (cryo-ET) reconstructs electron microscopy images of frozen large molecules, complexes or cells at high-resolution in 3D. Here, an image processing pipeline within the open source software RELION 5 used for such reconstructions readily enables data to go from unprocessed to high-res model building, aiding standardisation and newcomers to the field

Read the published research article here

Image from work by Alister Burt and Bogdan Toader, and colleagues

MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in bioRxiv, April 2024 (not peer reviewed)

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ER Remake

Greater understanding of the role of autophagy – the breakdown and recycling of components – in the remodelling of the cell's endoplasmic reticulum (the protein transporting organelle) in nerve development

Read the published research article here

Image from work by Melissa J. Hoyer, Cristina Capitanio and Ian R. Smith, and colleagues

Department of Cell Biology, Harvard Medical School, Boston MA; Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, USA

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in bioRxiv, November 2023 (not peer reviewed)

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Smuggling Tunnels

For decades, El Chapo was the world's most powerful drug trafficker. Using an elaborate network of tunnels, he smuggled more narcotics into the USA than anyone else on the planet. Scientists have discovered that SARS-CoV-2, the virus responsible for the COVID-19 pandemic, can use a similar trick to spread around the body. After being infected, some people suffer long COVID: symptoms like depression, fatigue, and 'brain fog' that last for months. We know SARS-CoV-2 can infect the brain, but we don't understand how, as most neurons lack the molecular 'lock' that the virus 'picks' to gain entry. Here, visualised by cryo-ET, we see SARS-CoV-2 viruses (dark blue) travelling inside and along the surface of a tunnelling nanotube (green). When SARS-CoV-2 infects a cell, it forces its host to build these tunnels to uninfected cells and smuggles itself through them. These results explain why COVID-19 affects the brain and may offer a new treatment target.

Written by Henry Stennett

Image by Anna Pepe, Chiara Zurzolo Lab, Institut Pasteur

Unité de Trafic Membranaire et Pathogénèse, Département de Biologie Cellulaire et Infection, Institut Pasteur, CNRS UMR3691, Université Paris Cité, Paris, France

Image copyright held by Anna Pepe, Institut Pasteur

Research published in Science Advances, July 2022

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