Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

At that star, turn left!

17.10.2002


Our bodies contain proteins that are made of smaller molecules that can be either left- or right-handed, depending upon their structure. Regardless of which hand we use to write, however, all human beings are `left-handed` at the molecular level. Life on Earth uses the left-handed variety and no one knows how this preference crept into living systems. In 2012, ESA`s Rosetta lander will land on a comet to investigate, among other things, if the origin of this preference lies in the stars.



Living cells use tiny organic molecules (called amino acids) to build proteins in the same way as children build things out of Lego bricks. Most amino acids come in two mirror-image varieties, right- and left-handed. The arrangement of the thumb and four fingers on a left hand is the mirror image of the arrangement on the right. In amino acids, the arrangement of the atoms determines whether the molecule is left- or right-handed.

Uwe Meierhenrich, at the University of Bremen, Germany, thinks that the Earth`s early supply of amino acids came from space, carried by comets. He is part of a European team who reproduced the way organic molecules form in space, to try to understand what the Rosetta lander might find on Comet Wirtanen in 2012.


At a laboratory in Leiden, The Netherlands, they lowered the temperature of a chamber to -261°C, pumped out the air, and injected a rarefied mixture of molecules known to exist in space: water, ammonia, and simple carbon molecules. These molecules froze onto artificial dust grains inside the chamber. They then shone an ultraviolet lamp onto the samples, to simulate starlight. "Our aim was to simulate interstellar conditions as accurately as possible. We did not adapt the conditions to produce amino acids," says Meierhenrich.

Using a version of Rosetta`s Cometary Sampling and Composition (COSAC) experiment, they found newly formed right- and left-handed amino acids in equal quantities. Earthly life, however, uses only left-handed amino acids. Experiments during the 1950s showed that adding right-handed amino acids to proteins stopped the proteins from growing. Was Earth supplied with more left-handed amino acids than right-handed ones in the beginning, allowing life to begin? One famous study has suggested this. Meierhenrich says, "The excess (of left-handed amino acids) found in the Murcheson meteorite is really small and some of the analyses are controversial. Rosetta will give us a much clearer picture."

Some scientists think the key to creating an excess of left over right is in the type of ultraviolet light that shines on the amino acids. When ultraviolet starlight strikes dust grains, it can begin to twist - either clockwise or anticlockwise. Depending on the direction in which it is twisting, it destroys one handedness of amino acid more than the other. In 1998, an international group of astronomers discovered large amounts of `twisty` light occurring naturally in the dusty cocoons of some young stars, where planets might be forming. "I think this is the most probable origin of the excesses," says Meierhenrich who is now using a Paris Laboratory where scientists can twist ultraviolet light to recreate these conditions.

We may well find that Rosetta`s findings on Comet Wirtanen reliably indicate that our molecular left-handedness is indeed a legacy of the stars.

Monica Talevi | alfa
Further information:
http://www.esa.int

More articles from Life Sciences:

nachricht Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

UCLA engineers use deep learning to reconstruct holograms and improve optical microscopy

22.11.2017 | Medical Engineering

Watching atoms move in hybrid perovskite crystals reveals clues to improving solar cells

22.11.2017 | Materials Sciences

New study points the way to therapy for rare cancer that targets the young

22.11.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>