Pass it on Researchers have discovered an unusual epigenetic heirloom that can be passed down more than 14 generations.
M
any families have heirlooms – special items that are passed down the generations, transferring precious memories of bygone times. For tiny nematode worms, this treasure takes the form of chemical marks in the genome, transmitting information about what life was
like in the past. Impressively, these cellular memories can be passed down for at least 14 generations – although because worms live, breed and die in the space of a few days, that’s still only a few months. The discovery, published by CRG group leader Ben Lehner in collaboration with researchers from the Josep Carreras Leukaemia Research Institute (IJC) and the Institute for Health Science Research Germans Trias i Pujol (IGTP), was initially made by accident. His PhD student Adam Klosin was studying C. elegans worms carrying a transgene array – a long string of repeated copies of a gene encoding a red fluorescent protein – when he noticed something strange. If the worms were kept at 20˚C, the array of transgenes was less active, creating only a small amount of fluorescent protein. But shifting the animals to a warmer climate of 25˚C significantly increased the activity of the transgenes, making the animals glow bright red under ultraviolet light.
Then things got really weird. When these worms were moved back to the cooler temperature, their transgenes were still highly active, suggesting they were somehow retaining the ‘memory’ of their warmer youth. Intriguingly, the bright fluorescence was passed on to their offspring and onwards for another seven generations living at the cooler temperature, even though the original animals only experienced the higher temperature for a brief time. Amazingly, keeping worms at 25 degrees for five generations led to the increased transgene activity being maintained for at least 14 generations once the animals went back to a colder life. “It’s super cool!” Lehner jokes. “This is an artificial system, but the effect is really pronounced. We had to find out what was causing it so Adam abandoned his original PhD project and started working on this instead.”
Executive Summary 2017 - 23