Started by Icarus, December 13, 2014, 11:41:28 PM
QuoteUCLA geochemists have found evidence that life likely existed on Earth at least 4.1 billion years ago -- 300 million years earlier than previous research suggested. The discovery indicates that life may have begun shortly after the planet formed 4.54 billion years ago.The research is published today in the online early edition of the journal Proceedings of the National Academy of Sciences."Twenty years ago, this would have been heretical; finding evidence of life 3.8 billion years ago was shocking," said Mark Harrison, co-author of the research and a professor of geochemistry at UCLA.. . .The researchers, led by Elizabeth Bell -- a postdoctoral scholar in [Mark] Harrison's laboratory -- studied more than 10,000 zircons originally formed from molten rocks, or magmas, from Western Australia. Zircons are heavy, durable minerals related to the synthetic cubic zirconium used for imitation diamonds. They capture and preserve their immediate environment, meaning they can serve as time capsules.The scientists identified 656 zircons containing dark specks that could be revealing and closely analyzed 79 of them with Raman spectroscopy, a technique that shows the molecular and chemical structure of ancient microorganisms in three dimensions.Bell and [Patrick] Boehnke, who have pioneered chemical and mineralogical tests to determine the condition of ancient zircons, were searching for carbon, the key component for life.One of the 79 zircons contained graphite -- pure carbon -- in two locations."The first time that the graphite ever got exposed in the last 4.1 billion years is when Beth Ann and Patrick made the measurements this year," Harrison said.[Continues . . .]
QuoteThe crucibles that bore out early building blocks of life may have been, in many cases, modest puddles.Now, researchers working with that hypothesis have achieved a significant advancement toward understanding an evolutionary mystery -- how components of RNA and DNA formed from chemicals present on early Earth before life existed.In surprisingly simple laboratory reactions in water, under everyday conditions, they have produced what could be good candidates for missing links on the pathway to the code of life.And when those components joined up, the result even looked like RNA.As the researchers' work progresses, it could reveal that much of the original chemistry that led to life arose not in fiery cataclysms and in scarce quantities, but abundantly and gradually on quiet, rain-swept dirt flats or lakeshore rocks lapped by waves.[Continues . . .]
QuoteComplex life, as we know it, started completely by chance, with small strands of molecules linking up, which eventually would have given them the ability to replicate themselves.In this world, billions of years ago, nothing existed that we would recognise today as living. The world contained only lifeless molecules that formed spontaneously through the natural chemical and physical processes on Earth.However, the moment that small molecules connected and formed larger molecules with the ability to replicate themselves, life started to evolve."Life was a chance event, there is no doubt about that," says Dr Pierre Durand from the Evolution of Complexity Laboratory in the Evolutionary Studies Institute at Wits University, who led a project to find out how exactly these molecules linked up with each other. Their results are published today in the journal Royal Society Open Science, in a paper entitled "Molecular trade-offs in RNA ligases affected the modular emergence of complex ribozymes at the origin of life".Very simple ribonucleic acid (RNA) molecules (compounds similar to Deoxyribonucleic acid(DNA)) can join other RNA molecules to themselves though a chemical reaction called ligation. The random joining together of different pieces or RNA could give rise to a group of molecules able to produce copies of themselves and so kick start the process of life. While the process that eventually led to the evolution of life took place over a long period of time, and involved a number of steps, Wits PhD student Nisha Dhar and Durand have uncovered how one of these crucial steps may have occurred.They have demonstrated how small non-living molecules may have given rise to larger molecules that were capable of reproducing themselves. This path to self-replicating molecules was a key event for life to take hold. "Something needed to happen for these small molecules to interact and form longer, more complex molecules and that happened completely by chance," says Durand.[Continues . . .]
QuoteLigases (and related polymerases) have primarily been explored with the aim of evolving a self-replicating enzyme. However, while these self-replicating ribozymes are key components of a replicating RNA world, an explanation is needed for the emergence of such molecules that are much larger in size than those that formed spontaneously in the prebiotic world. This study reveals how the activity of small ligases could have led to larger, more complex molecules. The ligases exhibited differential functional flexibility and efficiency which correlated with their size and stability. The results indicate that, in the early stages of the RNA world, molecular size could have increased in a modular, stepwise fashion via the reactions of small ligases with a range of oligomers, albeit with a relatively poor efficiency. It supports the computational and theoretical predictions that assembly of larger functional molecules resulted from short RNA ligases. The derived larger and more complex ligases developed specificity and efficiency for the kinds of substrates ligated. This trade-off could have contributed to building molecular complexity and the generation of a pool of functionally specialized molecules, which were necessary for the emergence of a self-sustained replicating system.
QuoteScientists have created a new type of genetic replication system which demonstrates how the first life on Earth -- in the form of RNA -- could have replicated itself. The scientists say the new RNA utilizes a system of genetic replication unlike any known to naturally occur on Earth today.A popular theory for the earliest stages of life on Earth is that it was founded on strands of RNA, a chemical cousin of DNA. Like DNA, RNA strands can carry genetic information using a code of four molecular letters (bases), but RNA can be more than a simple 'string' of information. Some RNA strands can also fold up into three-dimensional shapes that can form enzymes, called ribozymes, and carry out chemical reactions.If a ribozyme could replicate folded RNA, it might be able to copy itself and support a simple living system.Previously, scientists had developed ribozymes that could replicate straight strands of RNA, but if the RNA was folded it blocked the ribozyme from copying it. Since ribozymes themselves are folded RNAs, their own replication is blocked.Now, in a paper published today in the journal eLife, the scientists have resolved this paradox by engineering the first ribozyme that is able to replicate folded RNAs, including itself.[. . .]Dr Nathan Richardson, Head of Molecular and Cellular Medicine at the MRC, said: "This is a really exciting example of blue skies research that has revealed important insights into how the very beginnings of life may have emerged from the 'primordial soup' some 3.7 billion years ago. Not only is this fascinating science, but understanding the minimal requirements for RNA replication and how these systems can be manipulated could offer exciting new strategies for treating human disease."[Link to full article.]
Quote from: No one on May 31, 2018, 10:13:27 PMSo, it wasn't a wave of a magic wand?
Quote from: Icarus on June 02, 2018, 07:04:24 AMPrince Charlie may be onto something. The May edition of Scientific American has a rather interesting article about deep sea mining. There are minerals on the bottom of the ocean that have been accumulating in useful quantities for a million years or so. Those minerals, metals actually, are thousands of feet below the surface. The process of extraction involves dredging and also scraping of undersea rock formations. The problem is that such displacement of the natural environment is likely to influence, even destroy, some of the animal and bacterial life that helps keep the ocean "clean". Nickle, Cobalt and copper are some of the deposits that are being depleted on terra firma. There is ample deposit of those metals far down in the briny deep. Mining them may cause a great deal of distress to the ocean and its' inhabitants.See International Seabed authority ....www.isa.org.jm or the Scripps Institute of Oceanography at.. www.mod.uscd.edu/plumex
QuoteA new look at old data from NASA's Cassini orbiter shows complex organic molecules are gushing from the tiny moon [Enceladus]Complex organic molecules have been discovered for the first time coming from the depths of Saturn's moon Enceladus, a new study reported.Spacecraft scheduled to launch soon could explore what this new discovery says about the chances of life within icy moons like Enceladus, the study's researchers said.The sixth largest of Saturn's moons, Enceladus is only about 314 miles (505 kilometers) in diameter. This makes the moon small enough to fit inside the borders of Arizona.