The next morning, from Amsterdam’s Schiphol airport, I catch a KLM craft bound for Sweden. We touch down in Stockholm where Greta Garbo and Ingrid Bergman were born. The archipelago stretches 80 km east of the city with over 24 000 islands dotted across the Baltic Sea. The ‘City of Bridges’ commandeers fourteen islands on lake Mälaren fusing the charm of the old world with the sophistication of city skyscrapers. A swish Swedish train takes me to Huddinge to meet Karl Ekwall (Karolinska Institute).

Karl tells me about the positive and negative regulators of gene expression. “Genes may be expressed differently in a liver versus a brain cell and that can be regulated by epigenetic markers,” he explains. “Some of those markers are modifications on histones, the basic proteins used to compact DNA. There was a big breakthrough in this field in 1996 when people isolated enzymes that change these epigenetic marks.” Like Fred, Karl is aware that understanding epigenetic mechanisms could lead to new therapies. “It’s important because in many different diseases, cancer for example, the epigenetic marks are wrong and that causes a tumour.” Karl looks at histone tags in a different kind of yeast not used in marmite, bread or brewing.
 
Fission yeast is a cousin of the budding kind. Both kinds have around 2000 genes in common with humans. Karl and his team are making maps of epigenetic marks across the yeast genome. They are flagging up points at which enzymes bind to remove tags like acetyl groups. “The aim is to understand how these enzymes actually regulate genomes,” says Karl. Recently he discovered something unexpected. “The very same enzyme that is supposed to transcribe the genes is actually involved in turning off parts of the genome”.

This novel role for the intermediary between our genetic code and functional protein highlights how much we have yet to understand about how DNA is controlled.

And with that revelation, Sweden sees me wave goodbye to my epigenetic adventures. After ten European countries I’ve only scratched the surface of this exciting research field. Yet this small sample of the network has opened my eyes to a new language, a new way of thinking about DNA and genes. The words are the same, but the grammar is evolving exponentially, and the emergent picture is very different to that painted by my old biology textbooks. Down with dogma!