What are Circadian rhythms and what's the connection with transgenic flies?
Circadian rhythms are the patterns of activity that occur on a 24-hour cycle. These rhythms are important biological regulators in virtually every living creature. In mammals, the internal circadian clock resides in the brain, and sunlight is the cue that rewinds this clock daily. “Researchers have now found a biochemical pathway that senses blue light, and thereby connects the sun to molecular components of the circadian clock,” says Joseph Takhashi, , a researcher at Northwestern University.
“Although the existence of a circadian clock in humans had been postulated for decades, an understanding of the molecular mechanisms has required the full complement of research tools. To gain the initial insights into circadian mechanisms, researchers turned to genetically tractable model organisms such as transgenic flies.”
Transgenic organisms are creatures that contain foreign DNA that has been inserted in the laboratory. This foreign DNA becomes a "marker" which allows scientists to study the course of biological processes. The transgenic flies, like all flies, have their particular circadian rhythms, but the bodies of these with this marker inserted will glow when a certain gene involved in the circadian cycle is activated. This is then used to study the change in the molecules that regulate the circadian rhythm, simply by observing if the fly glows or not. See more at the link: