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  • richardmitnick 7:27 am on August 21, 2015 Permalink | Reply
    Tags: 1.5 billion year old water, , , , , Origin of Life   

    From New Scientist: “Watery time capsule hints at how life got started on early Earth” 


    New Scientist

    20 August 2015
    Colin Barras

    The chemical reactions around hydrothermal vents at the bottom of ancient seas could have kick-started life (Image: Dr Bob Embley/NOAA PMEL)

    It has all the ingredients of a primordial soup. What’s more, the chemicals of life – discovered in a pocket of water that last saw the light of day 1.5 billion years ago – appear to have formed without any influence from biological processes.

    That means the idea that life got started as a result of chemical reactions around deep-sea vents looks more likely.

    Barbara Sherwood Lollar at the University of Toronto in Ontario, Canada, and her team discovered the water a few years ago oozing from rocky fractures 2 kilometres below the surface at the Kidd mine near Timmins in Ontario. The water, which is about 1.5 billion years old, appears to show no signs of life – an extremely rare find .

    The rocks are the ancient remains of hydrothermal vents formed at the bottom of Earth’s early oceans, and that means the water they contain could reveal important details about the chemistry that might have occurred at such vents before life began exerting its influence.

    Hot, chemical-laced water gushes out of deep-sea hydrothermal vents – conditions that in theory would be ideal for the origin of life.

    But it is a difficult idea to test. “The chemistry is often heavily overprinted by life,” Sherwood Lollar says.

    Her team has previously found a wealth of complex organic molecules in the water.

    Now her colleague, Christopher Glein, has performed a raft of calculations to show that all of those molecules could have formed through perfectly feasible abiotic chemical reactions in the conditions found in such ancient hydrothermal vents.

    His calculations show the conditions were particularly favourable for the formation of some key chemicals, including glyceraldehyde, one of the precursors of RNA and DNA, and pyruvate, which is important for cell metabolism.

    Traditionally, biochemists have considered these molecules to be relatively hard to generate abiotically, says Glein who presented his findings at the Goldschmidt conference in Prague this week. “But that’s assuming they are being synthesised under familiar conditions at Earth’s surface,” he says.

    Conditions are very different in the ancient hydrothermal vents, they found. The water there has reacted with the rock through a process called serpentinisation to create an environment poor in oxygen but rich in hydrogen, iron and sulphur. Combined with temperatures of about 100 °C – also found there – many complex organic compounds can easily form.

    Sample of serpentinite from the Golden Gate National Recreation Area, California, USA

    William Martin at the University of Düsseldorf, Germany, says hydrothermal vents would have allowed for even more complex things to form. “I say that hydrocarbon synthesis at serpentinising systems is enough to make even the first membranes,” he says.

    Glein emphasises that the water pockets in Kidd mine, while ancient, are not as old as life on Earth itself.

    “We’re not claiming that Kidd actually contains the original prebiotic soup, or a second origin of life,” he says – but it’s a useful system for understanding the kind of hydrothermal chemistry that might have helped kick-start life about 4 billion years ago. “While not the first brand of prebiotic soup, it’s a variety that can potentially provide new clues about the origin of life.”

    See the full article here.

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  • richardmitnick 2:46 pm on March 7, 2015 Permalink | Reply
    Tags: , , , Origin of Life   

    From astrobio.net: “NASA Ames Reproduces the Building Blocks of Life in Laboratory” 

    Astrobiology Magazine

    Astrobiology Magazine

    Mar 7, 2015
    No Writer Credit

    Left to right: Ames scientists Michel Nuevo, Christopher Materese and Scott Sandford reproduce uracil, cytosine, and thymine, three key components of our hereditary material, in the laboratory. Image Credit: NASA/ Dominic Hart

    NASA scientists studying the origin of life have reproduced uracil, cytosine, and thymine, three key components of our hereditary material, in the laboratory. They discovered that an ice sample containing pyrimidine exposed to ultraviolet radiation under space-like conditions produces these essential ingredients of life.

    Pyrimidine is a ring-shaped molecule made up of carbon and nitrogen and is the central structure for uracil, cytosine, and thymine, which are all three part of a genetic code found in ribonucleic (RNA) and deoxyribonucleic acids (DNA). RNA and DNA are central to protein synthesis, but also have many other roles.

    “We have demonstrated for the first time that we can make uracil, cytosine, and thymine, all three components of RNA and DNA, non-biologically in a laboratory under conditions found in space,” said Michel Nuevo, research scientist at NASA’s Ames Research Center, Moffett Field, California. “We are showing that these laboratory processes, which simulate conditions in outer space, can make several fundamental building blocks used by living organisms on Earth.”

    An ice sample is deposited on a cold (approximately –440 degrees Fahrenheit) substrate in a chamber, where it is irradiated with high-energy ultraviolet (UV) photons from a hydrogen lamp. The bombarding photons break chemical bonds in the ices and break down the ice’s molecules into fragments that then recombine to form new compounds, such as uracil, cytosine, and thymine.

    Pyrimidine is a ring-shaped molecule made up of carbon and nitrogen and is the central structure for uracil, cytosine, and thymine, which are found in RNA and DNA. Image Credit: NASA

    NASA Ames scientists have been simulating the environments found in interstellar space and the outer Solar System for years. During this time, they have studied a class of carbon-rich compounds, called polycyclic aromatic hydrocarbons (PAHs), that have been identified in meteorites, and which are the most common carbon-rich compound observed in the universe. PAHs typically are structures based on several six-carbon rings that resemble fused hexagons, or a piece of chicken wire.

    The molecule pyrimidine is found in meteorites, although scientists still do not know its origin. It may be similar to the carbon-rich PAHs, in that it may be produced in the final outbursts of dying, giant red stars, or formed in dense clouds of interstellar gas and dust.

    “Molecules like pyrimidine have nitrogen atoms in their ring structures, which makes them somewhat wimpy. As a less stable molecule, it is more susceptible to destruction by radiation, compared to its counterparts that don’t have nitrogen,” said Scott Sandford, a space science researcher at Ames. “We wanted to test whether pyrimidine can survive in space, and whether it can undergo reactions that turn it into more complicated organic species, such as the nucleobases uracil, cytosine, and thymine.”

    The ring-shaped molecule pyrimidine is found in cytosine and thymine. Image Credit: NASA

    In theory, the researchers thought that if molecules of pyrimidine could survive long enough to migrate into interstellar dust clouds, they might be able to shield themselves from destructive radiation. Once in the clouds, most molecules freeze onto dust grains (much like moisture in your breath condenses on a cold window during winter).

    These clouds are dense enough to screen out much of the surrounding outside radiation of space, thereby providing some protection to the molecules inside the clouds.

    Scientists tested their hypotheses in the Ames Astrochemistry Laboratory. During their experiment, they exposed the ice sample containing pyrimidine to ultraviolet radiation under space-like conditions, including a very high vacuum, extremely low temperatures (approximately –440 degrees Fahrenheit), and harsh radiation.

    They found that when pyrimidine is frozen in ice mostly consisting of water, but also ammonia, methanol, or methane, it is much less vulnerable to destruction by radiation than it would be if it were in the gas phase in open space. Instead of being destroyed, many of the molecules took on new forms, such as the RNA/DNA components uracil, cytosine, and thymine, which are found in the genetic make-up of all living organisms on Earth.

    “We are trying to address the mechanisms in space that are forming these molecules. Considering what we produced in the laboratory, the chemistry of ice exposed to ultraviolet radiation may be an important linking step between what goes on in space and what fell to Earth early in its development,” said Christopher Materese, another researcher at NASA Ames who has been working on these experiments.

    An ice sample is held at approximately -440 degrees Fahrenheit in a vacuum chamber, where it is irradiated with high energy UV photons from a hydrogen lamp. The bombarding photons break chemical bonds in the ice samples and result in the formation of new compounds, such as uracil. Image Credit: NASA/Dominic Hart

    “Nobody really understands how life got started on Earth. Our experiments suggest that once the Earth formed, many of the building blocks of life were likely present from the beginning. Since we are simulating universal astrophysical conditions, the same is likely wherever planets are formed,” says Sandford.

    Additional team members who helped perform some of the research are Jason Dworkin, Jamie Elsila, and Stefanie Milam, three NASA scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    The research was funded by the NASA Astrobiology Institute (NAI) and the NASA Origins of Solar Systems Program. The NAI is a virtual, distributed organization of competitively-selected teams that integrates and funds astrobiology research and training programs in concert with the national and international science communities.

    See the full article here.

    Please help promote STEM in your local schools.

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    Stem Education Coalition


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