Yao and Webb just published an awesome article in Nature vol. 442 that included some incredible photos that resolved the actual activation of a gene in real-time. Webb, a physicist from Cornell, pioneered the multi-photon fluorescence microscopy that made the images possible.
The results were stunning. "Within two weeks we had spectacular pictures," said Lis. The images included pictures of the genes (hsp70 genes) that protect flies from the effects of extreme heat. By cranking up the heat, the researchers could activate these genes, and by using fruit flies specifically bred to carry fluorescent proteins on HSF, they could watch the transcription factors in action.
"This is the first time ever that anyone has been able to see in detail, at native genes in vivo, how a transcription factor is turned on, and how it then is activated," said Webb.
I couldn't imagine a more fantastic application of new optical imaging technology than to look into the very fundamental mechanisms of life and actually see them unfold before our eyes.