August 8, 2013
The Right Temperature Makes Tasty Treat For Fruit Flies
April Flowers for redOrbit.com - Your Universe Online
Scientists call it the Goldilocks Principle. Animals can survive and breed only if the temperature is just right -- too hot and they will overheat; too cold and they will freeze. Animals have evolved very sensitive temperature sensors, which allow them to detect the relatively narrow margin in which they can survive.
Until recently, very little was known about how these sensors worked. A new study from Brandeis University has discovered a previously unknown molecular temperature sensor in fruit flies belonging to a protein family responsible for sensing tastes and smells.
The study, published online in Nature, reveals these types of sensors are present in disease-spreading insects like mosquitoes and tsetse flies. These findings may help scientists better understand how insects target warm-blooded prey -- like humans -- and spread disease. Carbon dioxide and heat attract biting insects like mosquitoes.
Paul Garrity, professor of biology in the National Center for Behavioral Genomics at Brandeis, says mosquitoes tend to bite the areas on a person's body where there is the most blood because those places are the warmest.
"If you can find a mosquito's temperature receptor, you can potentially produce a more effective repellent or trap," Garrity says. "The discovery of this new temperature receptor in the fruit fly gives scientists an idea of where to look for similar receptors in the mosquito and in other insects."
The research team, comprised of biology professor Leslie Griffith, associate professor of biochemistry Douglas Theobald, and postdoctoral fellows Lina Ni and Peter Bronk, found the newly discovered sensor belongs to a family of proteins called gustatory receptors. Gustatory receptors have been studied for more than a decade, but were never before linked to thermosensation, according to Garrity. Other gustatory receptors are used by prey-seeking insects to smell carbon dioxide and to taste sugar and bitter chemicals like caffeine.
One type of gustatory receptor in fruit flies, however, senses heat rather than taste or smell. This receptor, responsible for sensing external temperatures and triggering a quick response if temperatures exceed the fly's Goldilocks zone, is known as Gr28b.
By showing that the insect has distinct external and internal systems for thermal detection, the team's research reconciles previously conflicting views of how a fruit fly senses warmth.
Other insects, including those responsible for spreading diseases like malaria and sleeping sickness, likely have related systems. Better understanding of how insects respond to and sense heat could help scientists understand insect migration in response to rising global temperatures and the spread of disease through insect bites.
"This research has opened a new avenue to understand how animals respond to temperature," Garrity says. "It's important because heat detection is critical for the behavior of insects that spread disease, kill crops and impact the environment."