GENETIC engineers have just got a new set of tools. One group of scientists
in the US has designed switches that can flick genes into and out of action,
while another group has devised timers that activate genes like clockwork.
Tools like these should shed light on how genes interact. They also open up
the possibility of building complex genetic “circuits” to treat disease.
For more than a decade, biologists have had only two ways of activating
engineered genes. Either the gene is permanently active and produces a protein
all the time, or it is activated in response to some…
