When it comes to cancer, you’d think animals like elephants that live long and have many cell divisions would have a higher risk than shorter-lived creatures, like mice.
Surprisingly, that’s not the case. This surprising fact, discovered by scientist Richard Peto in 1975, is known as Peto’s paradox.
But why is this? Well, long-lived species have more advanced ways to fight off cancer than short-lived species.
This concept works for animals where rapidly dividing mutant cells can harm the health of the animal.
However, something similar to cancer can occur in the vast networks of fungi, called mycelia, and the researchers at Wageningen University & Research (WUR) think they know how some fungi outsmart this threat.
“Mycelia, the underground web of fungal filaments, can have mutations that make a nucleus more competitive but are bad news for the whole mycelium.
You could think of these as ‘nucleus cancers’,” explains Duur Aanen, one of the researchers.
The researchers think long-lived fungi, such as fairy ring-forming species, must have mechanisms to lower the risk of these “nucleus cancers.”
On the other hand, fast-growing, short-lived species don’t need such a mechanism.
Interestingly, these short-lived species can develop nucleus cancers if grown in a lab for longer than their usual lifespan in nature.
Past research showed these mutants lost the ability to fuse their fungal filaments together, which is key to the fungus’s growth.
So how do the long-lived fungi fight off these nucleus cancers? According to the researchers, the secret is in a structure known as a clamp connection, found only in mushroom-forming fungi.
Here’s how it works: During cell division in a mycelium, one of the two nuclei (each cell contains two different nuclei) takes a detour to the new daughter cell via a temporary side cell.
This side cell then fuses with the daughter cell, leaving behind a visible “clamp connection.”
“If the cell can’t fuse, that’s the end of the road for the cell and its nucleus,” explains Aanen. Aanen and his team propose that this fusion moment is a test for one of the nuclei.
Since previous research showed that the loss of the ability to fuse is the main way nucleus cancers develop, the clamp connection may act as a quality check, where the nuclei continuously test each other’s ability to fuse.
So, in essence, mushroom-forming fungi have evolved a cool trick to constantly check their nuclei for any signs of “nucleus cancers,” helping them stay healthy regardless of their size and lifespan.
That’s some pretty smart biology!
The study was published in the journal Microbiology and Molecular Biology Reviews.
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