#cryo-ct

Growing Brains

We’d be nothing without our neurons. These specialised cells send and receive messages that instruct us to walk, talk and everything in between through a network in our body called the nervous system, which originates from our brain. Neurons themselves have their own tree-shaped structure. The main body of the neuron is like the crown of a tree, and houses its genetic information, whilst projecting outwards from the neuron’s body, like the trunk of a tree, is the axon. Measuring up to a metre in length, the axon’s primary function is to carry electrical signals away from the neuron body towards other neurons. This modern-art style image, captures the ultrastructure of a growing axon in a lab-grown miniature brain (organoid) using a technique called electron cryo-tomography. The axon (edged by dark blue) contains smaller structures such as microtubules (magenta) and actin filaments (orange) which provide structural support and carry the all-important signals.

Written by Katy Pallister

Image by Patrick C Hoffmann and Stefano L Giandomenico, and colleagues

MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, UK

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

Published in eLife, October 2021

Pull Yourself Together

If we could zoom in on our tensing muscles, we’d see bundles of thick and thin filaments pulling together. Speedy chemical reactions form tiny ‘cross bridges’ between them and, a bit like a climbers finding a grip, one filament pulls itself along the other. This happens all the way down a muscle fibre – repeating regions or sarcomeres shorten and the overall muscle contracts, helping us lift the heavy shopping, or climb a wall. Here researchers use electron cryotomography to blast mouse muscle with beams of electrons, mapping out contours from tiny deflections made in each electron’s path. A computer simulation lifts the image into 3D, highlighting separate filaments in rainbows colours. At this level of detail, researchers can zoom in on the molecular makeup of sarcomeres and their cross bridges (seen here as sticky-out branches on the filaments), giving insight into muscle biology and eventually injury and disease.

Written by John Ankers

Video from work by Zhexin Wang and Michael Grange, and colleagues

Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany

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

Published in Cell, March 2021