A tiny plant called Arabidopsis thaliana just helped scientists unearth new clues about the daily cycles of many organisms, including humans. This is the latest in a long line of research, much of it supported by the National Institutes of Health, that uses plants to solve puzzles in human health.
While other model organisms may seem to have more in common with us, greens like Arabidopsis provide an important view into genetics, cell division and especially light sensing, which drives 24-hour behavioral cycles called circadian rhythms.
Some human cells, including cancer cells, divide with a 24-hour rhythm. One of the main human circadian rhythm genes, cryptochrome, has been associated with diabetes and depression. Both of these discoveries grew from work with plants.
"We don't have stems and we don't flower, but our body parts, like those of plants, are controlled by circadian clocks," says NIH geneticist Laurie Tompkins. "Clocks operate more or less the same way in all organisms, but some aspects of clock function are easier to study in plants."
The new work, released this week in the early online publication of Nature, investigated why Arabidopsis does its major stem-growing in the darka pattern common to most plants. Biologist Steve Kay and colleagues at the University of California, San Diego, report that a specific trio of proteins regulates the rhythm in Arabidopsis stems.
The group of proteins, called the evening complex, interacts in the early evening to silence two genes that usually promote plant growth. When the evening complex's activity trails off a few hours before dawn, proteins release the brakes on growth and plants enter their nightly phase of rapid stem elongation.
When Kay's team mutated the three genes that code for the evening complex, they noticed that this made the Arabidopsis biological clock run out of syncstems grew unusually long
|Contact: Emily Carlson|
NIH/National Institute of General Medical Sciences