CRISPR

In 1987, a Japanese researcher named Yoshizumi Ishino was sequencing a gene in E. coli and noticed, right next to it, 29 strange repetitive sequences separated by what looked like random DNA. He had no idea what to do with them. He published a footnote. Nobody cared for two decades. In 2005, Francisco Mojica, a microbiologist in Alicante, noticed that the "random" DNA stretches between the repeats were actually fragments of viruses. The bacterium was keeping a vaccination record. In 2007, Rodolphe Barrangou and Philippe Horvath (who were working at the dairy company Danisco to protect yogurt starter cultures) proved that CRISPR was a genuine adaptive immune system — the bacterium memorizes the viruses it has encountered and cuts their DNA if they come back. Five years later, Jennifer Doudna and Emmanuelle Charpentier repurposed this mechanism to edit any genome. Nobel Prize in Chemistry 2020. CRISPR has become such a staple of molecular biology that people forget it is first and foremost a bacterial defense against phages — discovered by accident in the margins of a paper nobody read.