The Nature Podcast: How cells use their own DNA to recall how their training has been affected by climate change and the melting of the polar ice caps

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There are variations in the speed of Earth’s rotation that can affect the length of a day. The melting of the polar ice caps is one of the factors that has been shown to affect the effect on Earth’s rotation. As global time kept by atomic clocks occasionally has to be altered to match Earth’s rotation, human-induced climate change may delay plans to add a negative leap-second to ensure the two align.

When the researchers deleted the gene encoding the TLR9 protein from mice, the animals had trouble recalling long-term memories about their training: they froze much less often when placed into the environment where they had previously been shocked than did mice that had the gene intact. These findings suggest that “we are using our own DNA as a signalling system” to “retain information over a long time”, Radulovic says.

It also suggests a tantalizing possibility: this cycle might be faulty in people with neurodegenerative diseases such as Alzheimer’s, causing a build-up of errors in a neuron’s DNA, says study co-author Jelena Radulovic, a neuroscientist at the Albert Einstein College of Medicine in New York City.

The cause of the inflammation was found to be a specific immune response to DNA fragments that occurs on the surface of cells. This inflammatory response is similar to one that immune cells use when they defend against genetic material from invading pathogens, Radulovic says. However, in this case, the nerve cells were responding not to invaders, but to their own DNA, the researchers found.

Neurons: What do we understand about memory formation and persistence inside neurons? A Neuroscientist’s Perspective on Persistence in Cells and Brains

Clara Ortega de San Luis, a neuroscientist who works with Ryan at Trinity College Dublin, says that these results bring much-needed attention to mechanisms of memory formation and persistence inside cells. She says there is not as much information about what happens inside neurons as there is about the connections between them.