STANFORD, Calif. A fruit fly's immune system can tell time, researchers at the Stanford University School of Medicine have found, and how hard it punches back against infections depends on whether the fly is snoozing or cruising. The discovery could have implications for human health, too.
Working with jerry-rigged, light-bulb-laden shoeboxes to manipulate the flies' daily cycle and with syringes small enough to inject measured amounts of germs into the wee winged ones, the investigators have shown that the insects' immune response waxes and wanes with the diurnal oscillations called circadian rhythms.
Mimi Shirasu-Hiza, PhD, a postdoctoral scholar in the laboratory of David Schneider, PhD, assistant professor of microbiology and immunology, will present the findings Dec. 14 at the annual meeting of the American Society for Cell Biology, held in San Francisco.
Insects do not have the advanced artillery that characterizes vertebrate immune systems antibody-secreting B-cells, and killer and helper T-cells that precisely target specific pathogens for attack. But they do share with vertebrate organisms a primitive, but critical, rough-and-ready response to unwanted microbes: the innate immune system. This all-important first line of defense, without which we wouldn't survive an infection for the week or two it takes for our more-sophisticated antibodies and T-cells to kick into high gear, whirls into action at once, based on its ability to recognize generic patterns that distinguish microbial pests.
One feature of the fruit fly's innate immune system is the presence of circulatory cells called phagocytes that, like our own white blood cells, engulf and digest bacteria. In their new research, Shirasu-Hiza and Schneider have found that phagocytes' activity oscillates throughout the day.
Like the mosquito, platypus and whitetail deer, fruit flies are crepuscular they are most active at dawn and dusk, tend to roam a bit du
|Contact: Bruce Goldman|
Stanford University Medical Center