A recent claim that tardigrades got a sixth of their DNA from microbes is starting to unravel.
Ed Yong in The Atlantic:
Last Monday, a team from the University of North Carolina at Chapel Hill published the first ever genome of a tardigrade—a group of endearing microscopic animals with a reputation for being nigh-invincible. Astonishingly, as we reported last week, they found that around 6,600 of the animal’s genes—a full sixth of its genome—had jumped in from bacteria and other foreign sources. And perhaps, they speculated, this massive horizontal gene transfer (HGT) explained the tardigrade’s famed ability to withstand extreme conditions.
Just one week later, those claims are starting to unravel. A second team from the University of Edinburgh had also been sequencing the genome of the same species of tardigrade, ordered from the same supplier. And their results, released on Tuesday as a preprint paper, are totally different.
They found very few horizontally transferred genes—as few as 36, and just 500 at the very most. They concluded that their rivals had sequenced DNA from bacteria that were living alongside the tardigrades and, despite their best efforts, had mistaken the genes of those microbes for genuine tardigrade genes.
More here.