The Futile Cycle

Two interesting papers this week, one on the cyanobacterial circadian clock in PLoS Biology and the other on a global map of histones in yeast (subscription to Nature required).

The circadian clock paper is pretty neat, in that they figure out how the cyanobacterial circadian clock could be so simple, a mixture of three different proteins with ATP. It even works and oscillates with a 24 hour cycle in a test tube. They really get into the meat of the clock, and it gets pretty complex, even for “just” three proteins, to the point that they bring in a mathematician to model their ideas and verify what they suspect. The math is nothing that remarkable, but I find circadian oscillator mechanism that they finally work out to be pretty neat.

The global map of histones is quite awesome. The authors take the yeast nucleus, ChIP out the H2A.Z nucleosome-wrapped DNA (H2A.Z is traditionally a signal of the promoter and/or transcribed region), and then sequence every fragment of DNA in parallel, getting a map of H2A.Z nucleotide positioning in the yeast genome at a much higher resolution than any ChIP-chip data would give. Just a couple years ago, even to think of this sort of project would have been preposterous and probably denied funding, but with new advances in computer technology, robotics, and techniques like pyrosequencing, we get technologies like this massively parallel DNA fragment pyrosequencing. Just breath-taking. And take a look at the beautiful picture of DNA dinucleotide sequence correlation to position along the nucleosome:

This kind of huge scale experiment is a bit unwieldy, I guess, but it’s also incredibly cool when people pull off this sort of project.

Papers Referenced:
Mori et al., (2007) PLoS Biol., 5, e93.
Albert et al., (2007) Nature, 446, 572-576.

Follow the comments thread by the RSS 2.0 feed. You can leave a response, or trackback from your own site.