Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First biomarker for human sleepiness identified in fruit flies

13.12.2006
Scientists have identified the first biochemical marker linked to sleep loss, an enzyme in saliva known as amylase, which increases in activity when sleep deprivation is prolonged.

Researchers hope to make amylase the first of a panel of biomarkers that will aid diagnosis and treatment of sleep disorders and may one day help assess the risk of falling asleep at the wheel of a car or in other dangerous contexts.

"As we prepare for the holiday season and long drives to distant relative's houses, I hope this finding will get people thinking about the dangers and costs of sleep deprivation," says lead author Paul J. Shaw, Ph.D., assistant professor of neurobiology. "If you're feeling sleepy on your way over the river and through the woods to grandmother's house, it's much better to pull over and find a place where you can sleep for a while than to continue on and risk a serious accident."

The study appears this week in the online edition of Proceedings of the National Academy of Sciences. Shaw's lab was the first to show that fruit flies enter a state of inactivity comparable to sleep. They demonstrated that the flies have periods of inactivity where greater stimulation is required to rouse them. Like humans, flies deprived of sleep one day will try to make up for the lost time by sleeping more the next day, a phenomenon referred to as increased sleep drive or sleep debt.

... more about:
»Biomarker »Deprivation »amylase »saliva

To identify a marker for sleep debt, Shaw decided to look in saliva. Easily accessible, saliva contains many of the substances found in blood and urine, making it an increasingly popular target for diagnostics. Saliva was also an attractive target for Shaw's lab because the brain areas that regulate sleep drive are known to send signals to the brain areas that regulate salivation.

To start his search, Shaw subjected the flies to different kinds of sleep deprivation and used microarrays to look for changes in activity in many different genes. Amylase levels consistently changed after sleep loss. Amylases are a family of enzymes found in the saliva that break down starch.

To verify amylase's connection to sleep loss, Shaw's lab monitored its activity level after sleep deprivation in different fruit fly lines genetically altered to modify their sleep drive.

In one key test, amylase did not increase in a fly modified to endure sleep deprivation longer than normal flies without incurring sleep debt. When scientists kept the same mutant flies awake for extended nine or 12 hour stretches that normally cause them to incur sleep debt, their amylase levels increased.

"This helped prove that the increases in amylase activity level we were seeing weren't just triggered by wakefulness," Shaw says.

Humans kept awake for 28 hours also had increased amylase levels versus controls allowed to sleep normally.

Shaw's lab previously showed that they can use caffeine and methamphetamine to keep flies awake. Caffeine inflicts sleep debt, causing flies to sleep for extended periods when it wears off, while methamphetamine does not. When they monitored fly amylase levels in response to these drugs, they found caffeine drove amylase activity up while methamphetamine did not.

Flies dosed with the herbicide paraquat did not have increased amylase levels, suggesting changes in amylase activity were not related to stress. Flies lacking the gene for amylase had normal sleep and waking cycles, showing that while amylase is tightly linked to sleep drive, it is not actively involved in its regulation.

"We're very pleased with how tightly amylase levels correlate with sleep debt, but for a good diagnostic test we're likely going to need more than one biomarker," Shaw says. "So we're going to continue to use the processes that we've developed to look for other substances that change in connection with the level of sleep debt."

Stephen L. Duntley, M.D., associate professor of neurology and director of the Washington University Sleep Medicine Center, is a frequent research collaborator with Shaw.

"Despite the tremendous medical and public health consequences of sleep debt, its measurement in humans relies upon unreliable subjective rating scales and expensive, often impractical sleep laboratory testing," Duntley says. "Simple, easily accessible biomarkers for sleep debt in humans would revolutionize our ability to conduct research on the causes and consequences of sleep deprivation and provide clinicians with valuable new tools for diagnosing and assessing treatment efficacy in patients with sleep disorders."

According to Shaw, sleepiness biomarkers will also prove useful to studies of sleep in animals.

"Cetaceans like killer whales, for example, are known to go for extended periods of time without sleep, and we'd like to know more about how that works and whether they incur sleep debt," Shaw says. "Until now, the main way to study sleep deprivation's effects on the brain has been to attach electrodes, which can be a bit awkward when your target is a killer whale. Hopefully the markers we develop will make these kinds of phenomena much easier to study."

Michael C. Purdy | EurekAlert!
Further information:
http://www.wustl.edu

Further reports about: Biomarker Deprivation amylase saliva

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>