Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Flies have morning and evening clocks

14.10.2004


Two groups of researchers have independently discovered the long sought dual body clocks in the brain of fruit flies that separately govern bursts of morning and evening activity.



Both research groups published their findings in the October 14, 2004, issue of the journal Nature. Howard Hughes Medical Institute researcher Michael Rosbash at Brandeis University led one group; François Rouyer at the Centre National de la Recherche Scientifique in France led the second group. Graduate students Dan Stoleru and Ying Peng of Brandeis were co-lead authors of the Rosbash group’s article.

In an accompanying News & Views article in the journal Nature, neurobiologist William J. Schwartz of the University of Massachusetts Medical School, writes, "A truly integrative circadian biology is close at hand, as researchers learn about an adaptable, layered system that has emergent properties at many levels of organization. Drosophila workers, who have been so effective at taking the clock apart, are now succeeding in putting it back together."


Biological clocks in both flies and humans operate on a 24-hour, or circadian (Latin for "about a day"), cycle. In humans, the clock’s influence is far-reaching, governing such functions as sleeping and waking, fluid balance, body temperature, cardiac output, and oxygen consumption. In the fruit fly Drosophila, however, the circadian clock has its most overt effect on the fly’s level of activity. In both flies and humans, the clocks are circuits of neurons that naturally oscillate with a circadian periodicity. Inside these cells, the molecular components of the clock are "rewound" daily by the effects of light and other stimuli.

According to Rosbash, the central clue to the existence of dual circadian clocks in the fly was the observation that flies have two activity peaks. "It was always intriguing that flies had two peaks of activity, in the morning and evening, with a siesta during the day and not very much activity at night," he said. "There are several ways to explain that, but one possibility was that there were two clocks running -- one governing the morning peak and one governing the evening peak."

Rosbash and his colleagues theorized that if dual circadian clocks existed, they would likely occupy different anatomical positions in the fly brain. They knew that the flies’ circadian-clock neurons included one distinctive cluster called the ventral lateral neurons and another called the dorsal lateral neurons. The ventral lateral neurons were known to express an important circadian signaling molecule called pigment dispersing factor (PDF). The dorsal lateral neurons did not express a known signaling molecule, but were part of a larger group of circadian neurons that express a gene for a circadian photoreceptor protein known as cryptochrome.

Starting with those parameters, Rosbash and his colleagues used genetic techniques to selectively deliver cell death genes to ablate specific groups of neurons. They then observed how these genetic deletions affected the flies’ activity. The experiments revealed that the PDF-expressing ventral lateral neurons govern the morning activity peak; while another group of neurons, including the dorsal lateral neurons, governs the evening activity peak.

In additional experiments, the researchers selectively disrupted the internal clock machinery of the circadian neurons. The studies showed that one set of circadian neurons drives the other. "It’s as if there is a wiring circuit from one set to the next and, under natural light conditions, one can regulate the physiology of another," said Rosbash. The scientists theorize that this type of coupling between two circadian oscillators coordinates the two activity peaks and aids responses to environmental factors such as seasonal changes in lightness and darkness.

Rosbash said that there is evidence that mammals, including humans, also possess such dual circadian systems and that the systems communicate with one another, but researchers have not yet been able to distinguish the systems anatomically or biochemically.

Rosbash and his colleagues will continue to explore the details of the different clocks. Such studies, he said, may offer an important opportunity for understanding general principles of neural structure and function. "The circadian neurons are one of the few circuits in neurobiology where we have a chance to understand at multiple levels how different sets of neurons communicate with each other -- including understanding the wiring rules, the biochemical rules and the functional behavioral rules," he said.

Jennifer Michalowski | EurekAlert!
Further information:
http://www.hhmi.org

More articles from Life Sciences:

nachricht Plant escape from waterlogging
17.10.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Study suggests oysters offer hot spot for reducing nutrient pollution
17.10.2017 | Virginia Institute of Marine Science

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

Im Focus: New nanomaterial can extract hydrogen fuel from seawater

Hybrid material converts more sunlight and can weather seawater's harsh conditions

It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Study suggests oysters offer hot spot for reducing nutrient pollution

17.10.2017 | Life Sciences

Breaking: the first light from two neutron stars merging

17.10.2017 | Physics and Astronomy

World first for reading digitally encoded synthetic molecules

17.10.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>