S6.20: That’s so extra: Exploring the weird world of extrachromosomal DNA
Hello, and welcome to Genetics Unzipped - the Genetics Society podcast, with me, Dr Kat Arney. In this episode we’re getting very extra, talking about extrachromosomal DNA - what it is, what it does, and why it’s responsible for all sorts of genetic shenanigans. Plus, we discover what happens when nature gets up to a spot of genetic engineering.
Before we start, I’d like to draw your attention to a radio series I think you might enjoy. Bug in the System: The Past, Present and Future of Cancer is a three part documentary series on BBC Radio 4, presented by me, taking a look at where cancer came from, where it’s going, and how we might finally beat it. In the first episode we delve back in time and expand across species to understand cancer as a deep biological phenomenon rather than a purely human disease. In the second, I discover why - despite more than a century of dedicated research and an arsenal of sophisticated drugs that cost a small fortune - we’re still not very good at treating advanced cancers that have spread around the body, thanks to a pesky little thing called evolution. And in the final show, I find out how we might finally be able to beat this evolutionary monster with a little help from some mischievous moths and our own immune systems.
These are all themes that I explored in my book, Rebel Cell: Cancer, Evolution and the Science of Life, and I’ve been so excited to work with a brilliant BBC producer Beth Sagar-Fenton to turn them into a radio series, interviewing some of the leading cancer researchers around the world as well as archaeologists, historians and patients. You can listen to all three parts of Bug in the System on the BBC Sounds app - just search for Bug In The System Kat Arney, or follow the link on the page for this podcast at Geneticsunzipped.com And, of course, if you want to delve deeper, my book Rebel Cell is still available in paperback and ebook from all good - and evil - bookstores.
One question I always like to ask researchers is ‘what’s really weird?’ It often throws up some fascinating phenomena that are on the frontiers of research, or curiosities from the past that deserve a closer look. Well, when I spoke to Professor Charles Swanton from UCL and the Francis Crick Institute for Bug in the System, his answer to that question was “Extrachromosomal DNA.” And because we didn’t have time to squeeze it into our radio show, I thought I’d do a bit more digging and share the story with you. So, here we go - let’s get a little bit extra.
AI-generated image via Canva
Going round in circles: The story of extrachromosomal DNA
When you think about DNA, I’m willing to bet you either zoom in to imagine the double helix itself, or zoom out, picturing DNA neatly bundled up into X-shaped chromosomes. But while it is true that most of our genome - a staggering 2 metres of DNA in every cell - is packaged into these structures, that’s not the whole story.
If you’ve been paying attention to our previous episodes, you’ll also know that mitochondria also have their own little package of DNA, as do chloroplasts - the light-harvesting structures in plants.
And then there’s the weird stuff.
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Nature’s genetic engineers
Extrachromosomal DNA may be weird, but it’s just one of the many ways that cells break the rules when it comes to chromosomal behaviour.
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Coming up from the Genetics Society!
The next Genetics Society meeting is on the Genetics of Future Food production and the Green Revolution 2.0. It’s running from the 7th to the 9th of November at Newcastle University in the UK, and registration is still open, with grants available for junior researchers, as well as a carers allowance, to support attendance at the meeting. Find out more and register for your place now by heading to genetics.org.uk/event
For more information about this podcast including show notes, transcripts, links, references, music credits and everything else head over to geneticsunzipped.com You can find us on Twitter @geneticsunzip and please do take a moment to rate and review us on Apple podcasts - it really makes a difference and helps more people discover the show.
This episode of Genetics Unzipped was presented by me, Kat Arney, with additional research and scripting by Miyako Rogers. It’s a First Create the Media production for The Genetics Society - one of the oldest learned societies dedicated to promoting research, training, teaching and public engagement in all areas of genetics. You can find out more and apply to join at genetics.org.uk. Our theme music was composed by Dan Pollard, and the logo was designed by James Mayall, audio production was by Emma Werner and our producer is Sally Le Page. Thanks for listening, and until next time, goodbye.
