Swap Meet

We inherit a blend of mum and dad’s genetic traits, but our DNA was a jumble even before sperm met egg. Mum’s DNA, for example, was 'mixed' during meiosis, when corresponding or homologous regions of DNA came together to swap bits, giving each egg a blend of her parent’s genes. Here synaptonemal complex (SC) proteins help this crossing over to happen – these tiny biological machines are carefully ‘expanded’ after bathing in stretchy chemicals, so they're visible under sensitive structured illumination microscopy. A bit like a magician holding two balloon animals before they twist together, 'arms' of the SC (highlighted in red) attach to homologous regions of DNA called chromosomes, while green ‘filaments’ attached to a central 'body' (purple) help bring them together. This vital stage of meiosis is one of the reasons we are who we are, a unique combination of our parents, and grandparents too.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Video from work by Fabian U. Zwettler and Marie-Christin Spindler, and colleagues
• University of Würzburg, Am Hubland, Würzburg, Germany
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Nature Communications, June 2020