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Swordfish sword under X-rays: SAXS explained

Learn how scientists use X-rays to study bones at a molecular level

Animated infographic. Scientists use X-ray techniques, such as bio-SAXS, to study molecular structures in various settings, even in the bone that forms the swordfish’s sword. Credit: Dorota Badowska, Cy Jeffries, Joana Carvalho, Isabel Romero Calvo, Da In Wi, Tabea Rauscher /EMBL

Did you know that swordfish use their long sword as a tool for hunting? Rather than using it like a sword, they use it as a club to stun their prey. However, despite being under heavy load during hunting, it doesn’t break easily.

A drawing of swordfish and a bubble containing a drawing of a molecular model. Both on blue background representing water.
Scientists use X-ray techniques, such as bio-SAXS, to study molecular structures in various settings, even in the bone that forms the swordfish’s sword. Credit: Joana Carvalho and Isabel Romero Calvo/EMBL

Scientists explore this material strength using various experimental techniques, such as SAXS. Because the swordfish sword is in many ways similar to the bones of older human adults, it can help in understanding human bone ageing.

A drawing showing an X-ray image of a swordfish’s sword and leg bones of a diving human adult. The blue background represents water.
The internal structure of the swordfish’s sword that gives it strength from base to tip has similarities to aged human bones. Credit: Joana Carvalho and Isabel Romero Calvo/EMBL

Bio-SAXS: biological small-angle X-ray scattering

Bio-SAXS lets scientists determine the shape and dynamics of proteins and other bio-molecules using X-rays.

X-ray experiments take place at specialised testing stations called beamlines in synchrotrons.

Bio-SAXS is very versatile – it can be used for samples in almost any form, e.g. liquid or solid.

During a bio-SAXS experiment, X-rays are shot at a biological sample and get scattered in a unique pattern as they pass through it. This pattern depends on the types of atoms and how they are arranged inside the sample.

A drawing of a cuvette filled with a liquid sample containing floating molecules. An X-ray passes through it and scatters into a circular pattern of tiny dots. The blue background represents water.
As the X-rays pass through the sample, they get scattered in a unique pattern that depends on the internal structure of the sample. Credit: Joana Carvalho and Isabel Romero Calvo/EMBL

Scientists then analyse the scattering pattern to ‘peek inside’ a material to work out the 3D structures of the molecules.

Bio-SAXS is very versatile – it can be used for samples in almost any form, e.g. liquid or solid. It allows studying how molecules change their structure in different conditions, and how they interact with each other. The molecular structures and interactions are what give materials their unique properties.

A drawing showing a bubble containing SAXS pattern and another bubble with a molecular model derived from that pattern. The blue background represents water.
Scientists analyse SAXS patterns using computational methods to work out the 3D structure of molecules. Credit: Joana Carvalho and Isabel Romero Calvo/EMBL

Understanding human bone ageing using the swordfish sword

Bio-SAXS has previously enabled scientists to examine the structure of mineral particles in the swordfish sword at both the young bone at its base and the old bone at its tip. Studying this could help us understand better why and how bones in older adults deteriorate with time.

A zoom into the swordfish sword at its tip and at its base shows more porosity and lower mineralisation in the bone structure at the base on the sword than at the tip. The blue background represents water.
SAXS and other experiments showed higher bone density and mineralisation at the tip of the swordfish sword bone, and more porosity and lower mineralisation at its base, which makes the bone at the base more flexible and therefore less likely to break during hunting. Credit: Joana Carvalho and Isabel Romero Calvo/EMBL

Other applications of bio-SAXS

Bio-SAXS helps scientists address other questions as well:

A drawing of four bubbles, each representing a different application of bio-SAXS. First bubble: two different molecular structures at different temperatures. Second bubble: a lipid nanoparticle. Third bubble: plastic bag in the water falls apart into tiny pieces. Fourth bubble: cells with elongated orange crystals inside them. The blue background represents water.
Bio-SAXS can be used to address various scientific questions. Credit: Joana Carvalho and Isabel Romero Calvo/EMBL

Download the full-size SAXS infographic

The infographic is available under the CC-BY-SA 3.0 IGO license.

This infographic was produced thanks to the collaborative effort of several people:
Concept and text: Dorota Badowska and Cy Jeffries/EMBL
Visual concept and design: Joana Carvalho, Isabel Romero Calvo/EMBL
Animation: Da In Wi/EMBL
Creative lead: Tabea Rauscher/EMBL
Scientific consultations: Clément Blanchet and Cy Jeffries/EMBL, Imke Fiedler and Felix Schmidt/UKE


Source article(s)

Tags: beamline, blanchet, explainer, hamburg, in cellulo structural biology, infographic, lipid nanoparticles, nanoplastic, pollution, small-angle x-ray scattering (saxs), structural biology, vaccine, x-ray

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