Scientists have sequenced the entire genome of the tardigrade, AKA the water bear, for the first time. And their results suggest that this weird little creature has the most foreign genes of any animal studied so far – or to put it another way, roughly one-sixth of the tardigrade’s genome was stolen from other species.
The new research has shown that approximately 6,000 of the tardigrade’s genes come from foreign species, which equates to around 17.5 percent.
We had no idea that an animal genome could be composed of so much foreign DNA. We knew many animals acquire foreign genes, but we had no idea that it happens to this degree.
So where is the tardigrade getting all its genes from? The foreign DNA comes primarily from bacteria, but also from plants, fungi, and Archaea.
The tardigrade has the ability to dry out until its body is less than 3 percent water, and then come bounce back once they’re rehydrated. When this desiccation happens, scientists know that their DNA breaks down into tiny pieces. They also know that when their cells rehydrate, there’s a point in time when the cell nucleus is leaky, allowing DNA and other molecules to pass through. That means that while the tardigrade is quickly patching up its own genome, it may accidentally be stitching in another organism’s genes.
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I have to trust them that this is not contamination.
