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TOPIC: Ingredients for life
Blobrana


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RE: Ingredients for life
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Scientists have shown that food enriched with natural isotopes builds bodily components that are more resistant to the processes of ageing. The concept has been demonstrated in worms and researchers hope that the same concept can help extend human life and reduce the risk of cancer and other diseases of ageing, reports Marina Murphy in Chemistry & Industry, the magazine of the SCI.
A team led by Mikhail Shchepinov, formerly of Oxford University, fed nematode worms nutrients reinforced with natural isotopes (naturally occurring atomic variations of elements). In initial experiments, worms’ life spans were extended by 10%, which, with humans expected to routinely coast close to the centenary, could add a further 10 years to human life.
Food enhanced with isotopes is thought to produce bodily constituents and DNA more resistant to detrimental processes, like free radical attack. The isotopes replace atoms in susceptible bonds making these bonds stronger.

‘Because these bonds are so much more stable, it should be possible to slow down the process of oxidation and ageing’ - Mikhail Shchepinov.

Isotopes could be used in foods or as a means to protect workers or soldiers from radiation. Deuterium, a natural isotope of hydrogen (with 2 protons rather than one) could be used routinely.
Previous successes in extending lifespan have involved withdrawing food to the point of near starvation, a process called caloric restriction.

Source : Society of Chemical Industry

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Blobrana


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A Simpler Origin for Life
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The sudden appearance of a large self-copying molecule such as RNA was exceedingly improbable. Energy-driven networks of small molecules afford better odds as the initiators of life.
Extraordinary discoveries inspire extraordinary claims. Thus James Watson reported that, immediately after they had uncovered the structure of DNA, Francis Crick "winged into the Eagle (pub) to tell everyone within hearing that we had discovered the secret of life." Their structure--an elegant double helix--almost merited such enthusiasm. Its proportions permitted information storage in a language in which four chemicals, called bases, played the same role as twenty six letters do in the English language.
Further, the information was stored in two long chains, each of which specified the contents of its partner. This arrangement suggested a mechanism for reproduction, that was subsequently illustrated in many biochemistry texts, as well as on a tie that my wife bought for me at a crafts fair: The two strands of the DNA double helix parted company. As they did so, new DNA building blocks, called nucleotides, lined up along the separated strands and linked up. Two double helices now existed in place of one, each a replica of the original.

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Blobrana


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Where did life come from?
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Although scientists have never been able to "create" life by executing the following "recipe" in a lab, some believe there's a simple answer. Let's take it gently. But remember, no one has ever been able to "create" life in a lab by combining chemicals, zapping it with electricity, or any other such method.

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Blobrana


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RE: Ingredients for life
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Title: New insights into the origin of life on Earth
Authors: Xiang V. Zhang and Scot T. Martin

In an advance toward understanding the origin of life on Earth, scientists have shown that parts of the Krebs cycle can run in reverse, producing biomolecules that could jump-start life with only sunlight and a mineral present in the primordial oceans. The Krebs cycle is a series of chemical reactions of central importance in cells — part of a metabolic pathway that changes carbohydrates, fats and proteins into carbon dioxide and water to generate energy.
Scot T. Martin and Xiang V. Zhang explain that a reverse version of the cycle, which
makes enzymes and other biomolecules from carbon dioxide, has been getting attention from scientists studying the origin of life. If the reverse cycle worked on a lifeless Earth, it could have produced the fundamental biochemicals needed for the development of more-advanced biological systems like RNA that could reproduce themselves.
In a report scheduled for the Dec. 13 issue of the weekly Journal of the American
Chemical Society, Martin and Zhang demonstrate that three of the five chemical reactions in the reverse Krebs cycle worked and produced biomolecules on the surface of a mineral believed to have been present in the waters of the early Earth. The mineral -- sphalerite -- acted as a photocatalyst that worked with sunlight to foster the chemical reactions.

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Source Journal of the American Chemical Society

Read more Weblink: “Driving Parts of Krebs Cycle in Reverse through Mineral Photochemistry”.

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Blobrana


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In just two years of work, an international research team has discovered eight new complex, biologically-significant molecules in interstellar space using the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) in West Virginia.

"This is a feat unprecedented in the 35-year history of searching for complex molecules in space and suggests that a universal prebiotic chemistry is at work" - Jan M. Hollis of the NASA Goddard Space Flight Centre, leader of the research team.

The new discoveries are helping scientists unlock the secrets of how the molecular precursors to life can form in the giant clouds of gas and dust in which stars and planets are born.

"The first of the many chemical processes that ultimately led to life on Earth probably took place even before our planet was formed. The GBT has taken the leading role in exploring the origin of biomolecules in interstellar clouds" - Phil Jewell of the National Radio Astronomy Observatory (NRAO).

GBTMolecules

The eight new molecules discovered with the GBT bring the total to 141 different molecular species found in interstellar space. About 90 percent of those interstellar molecules contain carbon, which is required for a molecule to be classified as organic. The newly-discovered molecules all contain carbon and are composed of 6 to 11 atoms each. These results suggest, the scientists say, that chemical evolution occurs routinely in the gas and dust from which stars and planets eventually are born. The mass of an interstellar cloud is 99 percent gas and one percent dust.
The GBT discoveries have been made in just two prototypical interstellar clouds. The molecules acetamide (CH3CONH2), cyclopropenone (H2C3O), propenal (CH2CHCHO), propanal (CH3CH2CHO), and ketenimine (CH2CNH) were found in a cloud called Sagittarius B2(N), which is near the center of our Milky Way Galaxy some 26,000 light years from Earth. This star-forming region is the largest repository of complex interstellar molecules known.
The molecules methyl-cyano-diacetylene (CH3C5N), methyl-triacetylene (CH3C6H), and cyanoallene (CH2CCHCN) were found in the Taurus Molecular Cloud (TMC-1), which is relatively nearby at a distance of 450 light years. The starless TMC-1 cloud is dark and cold with a temperature of only 10 degrees above absolute zero and may eventually evolve into a star-forming region.

"The discovery of these large organic molecules in the coldest regions of the interstellar medium has certainly changed the belief that large organic molecules would only have their origins in hot molecular cores. It has forced us to rethink the paradigms of interstellar chemistry" - Anthony Remijan of the NRAO.

These large molecules found with the GBT are built up from smaller ones, the scientists say, by two principal mechanisms. In the first, simple chemical reactions add an atom to a molecular structure residing on the surface of a dust grain. As an example of this process, the researchers cite a molecule called cyclopropenylidene (c-C3H2, where "c-" means cyclic), which contains three carbon atoms in a ring. Cyclopropenylidene was discovered in interstellar space in 1987, and is known to be highly reactive. In 2005, using the GBT, scientists discovered another molecule, cyclopropenone (c-H2C3O), which can be produced by adding an oxygen atom to cyclopropenylidene.
The second method for constructing larger molecules from smaller ones involves neutral-radical reactions that can occur within the gas in an interstellar cloud. For example, in 2006, the scientists discovered acetamide (CH3CONH2), which can be formed when a previously-discovered neutral molecule called formamide (HCONH2) combines with radicals such as CH2 and CH3, also previously discovered. Acetamide is particularly interesting because it contains a peptide bond which is the means for linking amino acids together to form proteins.
Once interstellar molecules are ejected from dust grains into the gas phase, presumably by shock waves, they are free to rotate end-over-end. As gas molecules change their rotational modes, they can emit or absorb radiation at precise radio frequencies, called transitions, that are unique to each type of molecule. By detecting several rotational transitions, astronomers can unambiguously identify a specific interstellar molecule.

"It is important to note that likely interstellar molecule candidates are first studied in gas-phase laboratory experiments so that transition frequencies are known in advance of an interstellar experiment" - Frank Lovas of the National Institute of Standards and Technology.

Along the line of sight from the interstellar cloud to the telescope, thousands of billions of molecules undergo the exact same transition, producing a signal strong enough to be detected by sensitive equipment. For this type of work, the GBT is the world's most sensitive tool that can be accurately pointed and track astronomical objects.
In addition to Hollis, Jewell, Remijan, and Lovas, the research team included Lewis Snyder of the University of Illinois; Harald Mollendal of the University of Oslo, Norway; Vadim Ilyushin of the Institute of Radio Astronomy of the National Academy of Sciences of the Ukraine; and Isabell Kleiner of the Universite Paris, France. The astronomers' reports on their results appeared in 8 separate editions of the Astrophysical Journal.

Source NRAO

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Blobrana


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Atomic Nitrogen
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Evidence of atomic nitrogen in interstellar gas clouds suggests that pre-life molecules may be present in comets, a discovery that gives a clue about the early conditions that gave rise to life, according to researchers from the University of Michigan and the Harvard-Smithsonian Centre for Astrophysics.
The finding also substantially changes the understanding of chemistry in space.
The question of why molecular nitrogen hasn't been detected in comets and meteorites has puzzled scientists for years. Because comets are born in the cold, dark, outer reaches of the solar system they are believed to be the least chemically altered during the formation of the Sun and its planets.
Studies of comets are thought to provide a "fossil" record of the conditions that existed within the gas cloud that collapsed to form the solar system a little more than 4.6 billion years ago. In this cloud, since nitrogen was thought to be in molecular form, and it follows that comets should contain molecular nitrogen as well.
But the reason it isn't there is because it isn't present in the gas clouds whose microscopic solid particles eventually form comets, said Sebastien Maret, research fellow in astronomy at the University of Michigan, and Edwin Bergin, a professor of astronomy at the University of Michigan. Those clouds contain mostly atomic nitrogen, not molecular nitrogen, as previously thought.
Maret, Bergin, and collaborators from Harvard-Smithsonian Centre for Astrophysics will publish their findings in the July 27 issue of the journal Nature.

The nitrogen bearing molecules in comets that crashed into Earth millions of years ago may have provided a sort of "pre-biotic jump start" to form the complex molecules that eventually led to life here.

"A lot of complex and simple biotic molecules have nitrogen and it's much easier to make complex molecules from atomic nitrogen. All DNA bases have atomic nitrogen in them, amino acids also have atomic nitrogen in them. By that statement what we're saying is if you have nitrogen in its simplest form, the atomic form, it's much more reactive and can more easily form complex prebiotic organics in space." - Edwin Bergin

These complex organics were incorporated into comets and were provided to the Earth.

"What we're seeing in space is telling us something about how you make molecules that led to us" - Edwin Bergin.

Also of importance is the fact that odd anomalies in isotopic values in meteorites can also be explained if the nitrogen is not molecular.

Source University of Michigan

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Blobrana


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Ingredients for life
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NASA's Spitzer Space Telescope has found the ingredients for life all the way back to a time when the universe was a mere youngster.
Using Spitzer, scientists have detected organic molecules in galaxies when our universe was one-fourth of its current age of about 14 billion years. These large molecules, known as polycyclic aromatic hydrocarbons, are comprised of carbon and hydrogen. The molecules are considered to be among the building blocks of life.
These complex molecules are very common on Earth. They form any time carbon-based materials are not burned completely. They can be found in sooty exhaust from cars and airplanes, and in charcoal broiled hamburgers and burnt toast.
The molecules, pervasive in galaxies like our own Milky Way, play a significant role in star and planet formation. Spitzer is the first telescope to see these molecules so far back in time.

"This is 10 billion years further back in time than we've seen them before" - Dr. Lin Yan of the Spitzer Science Center at the California Institute of Technology in Pasadena, California. Yan is lead author of a study to be published in the August 10 issue of the Astrophysical Journal. Previous missions - the Infrared Astronomical Satellite and the Infrared Space Observatory - detected these types of galaxies and molecules much closer to our own Milky Way galaxy. Spitzer's sensitivity is 100 times greater than these previous infrared telescope missions, enabling direct detection of organics so far away.

Since Earth is approximately four-and-a-half billion years old, these organic materials existed in the universe well before our planet and solar system were formed and may have even been the seeds of our solar system. Spitzer found the organic compounds in galaxies where intense star formation had taken place over a short period of time. These "flash in the pan" starburst galaxies are nearly invisible in optical images because they are very far away and contain large quantities of light-absorbing dust. But the same dust glows brightly in infrared light and is easily spotted by Spitzer.

Spitzer's infrared spectrometer split the galaxies' infrared light into distinct features that revealed the presence of organic components. These organic features gave scientists a milepost to gauge the distance of these galaxies. This is the first time scientists have been able to measure a distance as great as 10-billion light years away using the spectral fingerprints of polycyclic aromatic hydrocarbons.

"These complex compounds tell us that by the time we see these galaxies, several generations of stars have already been formed. Planets and life had very early opportunities to emerge in the universe." - Dr. George Helou of the Spitzer Science Center, a co-author of the study.

Other co-authors include Ranga-Ram Chary, Lee Armus, Harry Tepliz, David Frayer, Dario Fadda, Jason Surace, and Philip Choi, all of the Spitzer Science Center.

The Jet Propulsion Laboratory manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA. Spitzer's infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Dr. Jim Houck of Cornell.
The Infrared Astronomical Satellite was a joint scientific project sponsored by the United States, the Netherlands, and the United Kingdom. The Infrared Space Observatory was a European Space Agency mission with Japan's Institute of Space and Astronautical Science and NASA.


Credit: NASA/JPL-Caltech/L. Yan (SSC/Caltech)

This graph, or spectrum, charts light from a faraway galaxy located 10 billion light years from Earth. It tracks mid-infrared light from an extremely luminous galaxy when the universe was only 1/4 of its current age.
Spectra are created when an instrument called a spectrograph spreads light out into its basic parts, like a prism turning sunlight into a rainbow. They reveal the signatures, or "fingerprints," of molecules that make up a galaxy and contribute to its light.
Spitzer's infrared spectrometer identified characteristic fingerprints of complex organic molecules called polycyclic aromatic hydrocarbons, illustrated in the artist's concept in the inset. These large molecules comprised of carbon and hydrogen, are considered among the building blocks of life.
Scientists determined it took 10 billion years for photons from this galaxy to reach Spitzer's infrared eyes. These complex carbon and hydrogen molecules are from a young galaxy which is undergoing intense star formation, at the time the universe was only 3.5 billion years old.

These distant galaxies with enormous amounts of gas being converted into young stars are some of the most luminous objects in the sky. Enshrouded by dust, they are only faint, inconspicuous little dots in optical images. They are as bright as 10 trillion suns put together and 10 times brighter than starburst galaxies seen in our local universe.
This prompts a fascinating question as to what physical process is driving such enormous energy production in these galaxies when the universe is so young. These data were taken by Spitzer's infrared spectrograph in August and September 2004.

Source

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