Looking for junk DNA?
Looking for my review of an article on "junk DNA"? It's here.
Looking for my review of an article on "junk DNA"? It's here.
This week's paper is "Deletion of ultraconserved elements yields viable mice" by Nadav Ahituv and collaborators, published online in PLoS Biology.
The instructions for "life as we know it" are coded in DNA, but it appears that only a fraction of our DNA is ever used. (This is probably not true of our brains, myths notwithstanding.) At least, only a fraction of it is ever translated into proteins such as enzymes. Some of the untranslated (noncoding) DNA has known functions, such as coding for the RNA part of the ribosomes that translate messenger RNA into protein, but much appears to be junk. Much of the junk is multiple copies of transposons, bits of unusually selfish DNA that reproduce like rabbits and burrow into the chromosomes, sometimes presumably disrupting functional DNA.
But if the noncoding DNA is mostly useless junk, why has some of it apparently been preserved by natural selection?
A major paper was just published in Nature. “Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project” was written by a consortium involving contributions from many scientists. I will discuss a few of their more interesting findings, related to questions like "how much of our DNA doing something useful?"