Sea Urchins and our future

Fascinating research blogging post about the long life of Sea Urchins sans an innate adaptive immune system.

"Even though sea urchins are capable of reaching this old age, they do so without an adaptive immune system. Jawed vertebrates (that includes us) are the only species that have such an adaptive immune system. In a nutshell, this means that when we face a pathogen which we’ve never encountered before, our immune system ‘learns’ how to recognize the germ in future encounters, so that it can react faster next time. Because sea urchins don’t have this adaptive immunity, it is interesting to see how they evolved to deal with a wide variety of pathogens (them seas are full with bacteria and viruses!).
Scientists sequenced the sea urchin’s genome  in 2006. First analyses of the sea urchin quickly revealed the complexity of its immune system ². One of the most striking observation was the sheer amount of Toll-like Receptors (TLRs). In the sea urchin’s genome, 222 of these receptors could be identified, whereas most animals only have 1 to 20! TLRs are important for sensing different pathogenic signals. They can recognize bacterial cell wall components or viral RNAs, for example. In animals, TLRs only recognize the most conserved pathogenic signals. It has been suggested that this large expansion in TLR genes increases the spectrum of pathogens that can be recognized by the spiny fellow. This expansion is not exclusive to the family of TLRs, but also includes the NLR (203) and SRCR (218) gene families.
An interesting question would be if the expanded gene families in echinoderms (sea urchins, amongst others) resemble the Deuterostomian ancestor of Echinoderms (sea urchins and starfish) and Chordates. Maybe Chordates lost this expansion when they evolved an adaptive immune system? This seems to be supported by the fact that amphioxus, which is a closer relative to vertebrates but still lacks an adaptive immune system, also shows this expansion in immunologically related gene families.
So, there’s more to these globular animals than you might expect from their spiny first impression. I think this is another great example that shows us we can learn much about ourselves, evolution and how immunity works by the study of seemingly bizarre corners of the animal kingdom."

Soon one of these days, man will tinker our genome (for good) and increase the Toll-like Receptors or create another biomimicry so that we can reap the benefits. Well, all this possible only if people don't eat and convert them into excrement. In few centuries there is a good chance an exchange between a student and teacher might go like this:

"What do you mean our forefathers were gluttons and simply ate all biodiversity of the face of earth?"