From Nature, two articles demonstrating how micro RNA controls development of the nervous system pathways, and also control supression of extra X chromosomes since only one X should be in control. - http://www.nature.com/nature/journal/v460/n7255/edsumm/e090730-13.html - http://www.nature.com/nature/journal/v460/n7255/edsumm/e090730-12.html