June 14, 2007

RNA and metagenomics revolutions

The Economist looks at the RNA revolution

The DNA of a human cell is only a small part of the overall puzzle of what is going on within the human body.

Ever since the human-genome project was completed, it has puzzled biologists that animals, be they worms, flies or people, all seem to have about the same number of genes for proteins—around 20,000. Yet flies are more complex than worms, and people are more complex than either. Traditional genes are thus not as important as proponents of human nature had suspected nor as proponents of nurture had feared. Instead, the solution to the puzzle seems to lie in the RNA operating system of the cells. This gets bigger with each advance in complexity. And it is noticeably different in a human from that in the brain of a chimpanzee.

If RNA is controlling the complexity of the whole organism, that suggests the operating system of each cell is not only running the cell in question, but is linking up with those of the other cells when a creature is developing. To push the analogy, organs such as the brain are the result of a biological internet. If that is right, the search for the essence of humanity has been looking in the wrong genetic direction.

Recent work in metagenomics shows that we only have partial understanding or even recently awareness of 1% of the activity of microbes in human bodies

We contain 10 times more microbial than human cells and 100 times more microbial genes than human genes We are superorganisms of human and microbial parts.

10 to 100 trillion microbes perform functions in our body that we have not had to evolve

So we are now shedding light onto areas that we had very little awareness of until recently.