The world of genetics is filled with stories that are as gripping as the plot of any thriller. Take the IRGM gene – its saga, played out over millions of years, has all the makings of a classic drama. Act One: setting the scene. By duplicating and diverging, this gene thrived in the cells of most mammals as a trinity of related versions that played vital roles in the immune system.
Act Two: tragedy strikes. About 50 million years ago, in the ancestors of today’s apes and monkeys, the entire IRGM cluster was practically deleted, leaving behind a sole survivor. Things took a turn for the worse – a parasitic chunk of DNA called Alu hopped into the middle of the remaining gene, rendering it useless. IRGM was, for all intents and purposes, dead and it remained that way for over 25 million years of evolution.
Act Three: the uplifting ending. The future looked bleak, but IRGM’s fortunes were revived in the common ancestor of humans and great apes. Out of the blue, a virus inserted itself into this ancient genome in just the right place to resurrect the long-defunct gene. A fall from grace, a tragic demise and an last-minute resurrection – what more could you ask for from a story?
This twisting tale lies hidden in the genomes of the world’s mammals and it was discovered and narrated by Cemalettin Bekpen from the University of Seattle. To reconstruct the evolutionary story of the IRGM gene, Bekpen searched for it in a variety of different species.
(Oh come on – you try to find an image to illustrate this story!)