Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

No mid-day nap for Finnish flies

15.03.2017

Fruit flies from warm regions have a siesta, whereas their Nordic counterparts do not. Biologists from the University of Würzburg reset the circadian clock of African flies in an experiment. As a result, these insect also reduced the length of their siesta.

There are more than 2,000 species of fruit flies around the world. Some prefer warmer climates, whereas others are home in northerly latitudes. "We wanted to find out whether the circadian clock of the northern species differs from that of their southern relatives," explains Professor Charlotte Helfrich-Förster from the University of Würzburg's Biocenter. "For this purpose, we compared two fruit fly species from Finland with one from Tanzania."


African flies show active phases limited to the time around dusk and dawn; finnish dipterans in contrast have their activity peak in the early afternoon and stay active until nightfall, mostly without taking a siesta.

Long siesta at the equator

In the laboratory, the scientists varied the length of light and dark cycles to which the insects were exposed. In their first experiment, twelve hours of day were followed by twelve hours of night. This rhythm is typical for the equator where day and night are about equally long throughout the year.

The African flies exhibited a characteristic pattern of activity under these conditions: Their active phases were limited to the time around dusk and dawn; in the meantime they rested. In nature, such behaviour is highly advantageous as it allows the insects to better cope with the heat of the day.

Being slightly more relaxed in the morning, the Finnish dipterans in contrast had their activity peak in the early afternoon and stayed active until nightfall, mostly without taking a siesta. From a biological point of view, this behaviour makes sense, because even at the height of summer, the northern Scandinavian sun is rarely strong enough to harm the animals.

In the next step, the scientists extended the lab day: They left the lights on for 20 hours before turning them off again for four hours. In response to this, the Tanzanian flies did not extend their resting period, but rather started to bustle about long before dusk. Their activity now peaked at a time of day when it would normally still be scorching hot. If there were 20-hour days in Tanzania, such behaviour would probably be very risky.

Tiny differences in the flies' brains

So the Circadian clock of the southern flies seems to be geared to more or less constant day lengths. The interval between morning and evening activity always has about the same length. The Finnish specimens on the contrary adapted their activity pattern to the longer days: They used the extended period of light for more extensive foraging which was ended only by the onset of darkness. "So the circadian clocks of the two species seem to respond very differently to the modified day-and-night rhythms, Charlotte Helfrich-Förster points out."We asked ourselves why this is the case."

On the surface of it, the circadian clocks of all three species seem to be structured identically: Both the Finnish fruit flies and their Tanzanian counterparts have the same clock neurons – these are the nerve cells in the brain that make up the circadian system. Therefore, the Würzburg scientists took a closer look at the flies' brains. "We were able to show that the Finnish species produce no blue light photoreceptor in specific neurons, very unlike their African relatives," says Helfrich-Förster. "This means that the affected nerve cells do not have a sensor for day and night." Other neurons lack a molecule named PDF which usually passes on the incoming light-dark signals to other centres in the brain.

Resetting the fly clock

But are these differences really responsible for the altered activity pattern in the Scandinavian insects? To answer this question, the Würzburg scientists "reset" the circadian clock of the African Drosophila. Through genetic modification, they switched off the production of the blue light photoreceptor in those neurons in which it was missing in the Finnish flies, too. They proceeded similarly for the PDF. The result of the manipulation was striking: "The fruit flies from Tanzania now exhibited a rhythm of activity quite similar to that of their Finnish colleagues," Professor Helfrich-Förster emphasizes. "Also their siesta was less pronounced."

The ancestral fruit fly is believed to be of African origin. Over time, the insects also spread to cooler regions. The scientists assume that the flies' circadian clock also changed in the process, allowing the insects to adapt to the day length fluctuations and the lower intensity of the sun.

Pamela Menegazzi, Elena Dalla Benetta, Marta Beauchamp, Matthias Schlichting, Ingolf Steffan-Dewenter and Charlotte Helfrich-Förster: Adaptation of Circadian Neuronal Network to Photoperiod in High-Latitude European Drosophilids; Current Biology; DOI: 10.1016/j.cub.2017.01.036

Contact

Prof. Dr. Charlotte Helfrich-Förster, Department of Neurobiology and Genetics, T: +49 931 31-88823, E-Mail: charlotte.foerster@biozentrum.uni-wuerzburg.de

Gunnar Bartsch | Julius-Maximilians-Universität Würzburg

More articles from Life Sciences:

nachricht More genes are active in high-performance maize
19.01.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht How plants see light
19.01.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

More genes are active in high-performance maize

19.01.2018 | Life Sciences

How plants see light

19.01.2018 | Life Sciences

Artificial agent designs quantum experiments

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>