Gene Tales

MRNA structure

It’s not an overly interesting “tale” today: Jeffrey Tomkins writes Long Complex Gene Tails Defy Evolution. His topic is a new paper announcing the discovery that mice and humans can both have longer and more numerous 3′ UTRs (messenger RNA untranslated regions in the 3′ direction relative to the coding sequence – i.e. the magenta section of the above image) than previously thought. The new sequences that have been “conservatively” determined to be of this nature total 6.6 million bases in mice and 5.1 million in humans, which is quite a lot – something along the lines of 0.2% of the size of the entire human genome, though I’m not certain that they can be directly compared. Individually,

they identified 2035 mouse and 1847 human genes that have 3′ UTR tails ranging from 500 to 25,000 bases long. In some cases, they were even longer than the protein-coding areas of the genes themselves.

Tomkins points to the “hundreds to thousands of built in regulatory switches per gene RNA copy.” As you can tell from the title alone he is making a “that’s complex, so it’s out of reach of evolution” argument, which we’ve looked at ad nauseam. Given this, there are only two things that are worth clarifying: first, while the individual tails had lengths up to 25,000 bases long the vast majority were much shorter and the average was only a few thousand; second, while Tomkins claims that “[t]hese incredibly long gene tails literally contain hundreds to thousands of genetic switches within each single mRNA,” (emphasis added) the paper only says that “these extensions collectively contain thousands of conserved miRNA binding sites [Tomkins’ “switches”]” (emphasis added). The results are therefore not quite as impressive as they might be, and as Tomkins is selling them.