August 19, 2006

As Science Week Draws to a Close: Let's look at Humanity

I bet you didn't even know.

Researchers at the University of California have been looking at what seperates us from chimpanzees (apart from flinging poo), and have discovered Human Accelerated Regions (HAR) in the genome.
The article from the Scientist, that I read on the subject is very good, with the significance of Haussler's work being explained well, as well as the science behind it. It shows how biotechnology is used to give a picture of what genetic differences develop between species.

HAR aren't just found in humans, they are found in chickens and chimps (and presumably other mammals and birds, possibly reptiles?). The HAR genes that chickens have are practically the same as those in chimpanzees (2 significant differences), but the ones in humans are vastly more different (18 significant differences). Hence the name, these previously dormant stretches of non-protein coding DNA, rapidly vary as we move from our close relatives to us. They are (genetically speaking) most likely a key thing in what makes us humans, well human. It's super cool, in a totally genetic scientist geek sort of way.

The article explains the steps involved in working out what HAR, particularly HAR-1, are. HAR-1 doesn't code for a protein, which is not too special, quite a lot of DNA doesn't, but it's not absolute junk. HAR-1 codes for RNA, RNA are nucleic acid structures that exist outside the normal DNA structures in the nucleus - thus they can have an exo-nucleic role, affecting translation, transcription and other parts of genomics, proteomics and cell function. (RNA cheat sheet - there's even more than there were only 12 months ago when I was doing this at uni). RNA are pivotal in regulating gene expression in different species, and different systems within an organism. You don't want your skin cells generating the same proteins your spleen does - it could just get ugly.

These HAR express themselves in cells that play a key role in brain development in the foetus. Intelligence and brain function is one of those things that make humans human, making it more likely that HAR has a human-o-centric role in our genomme. In Nature's podcast, I heard that the researchers may consider popping the Human HAR-1 regions into mice, to see exactly what developmental changes would express themselves. Possibly we'll get really smart mice. While he did say that they weren't about to start playing Mozart, at least they aren't doing it with sharks. This too will hopefully yield some super-cool geeky results.

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