A very interesting article on a paper that just came out in Nature.
The nucleosome is made up of proteins known as histones, which are among the most highly conserved in evolution, meaning that they change very little from one species to another. A histone of peas and cows differs in just 2 of its 102 amino acid units. The conservation is usually attributed to the precise fit required between the histones and the DNA wound around them. But another reason, Dr. Segal suggested, could be that any change would interfere with the nucleosomes’ ability to find their assigned positions on the DNA.
There has been some really great work coming out recently on DNA regulation, the chemical coding by which genes are turned on or off in order to give cells with identical DNA their own functional identities - what makes a skin cell a skin cell and not a muscle or nerve cell.
Not my field, but I've been interested in this since taking embryology way back in biology class. All of the complicated things that happen within and between cells as they migrate and differentiate during development - it was fascinating, because at the time so little was known about the mechanisms behind them. In the last 10 - 15 years, though, they have finally begun to shed some light on some of these mechanisms.