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TOPIC: Primitive life


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RE: Primitive life
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Scientists have suspected that the three known domains of life -- eukaryotes, bacteria, and archaea -- branched off and went their separate ways around three billion years ago. But pinning down the time of that split has been an elusive task.
Now, a team of scientists present direct evidence that the three domains of life coexisted at least as long as 2.7 billion years ago.
The discovery came from chemical examination of shale samples, loaded with oily lipid remains of archaea found in a deep Canadian gold mine near Timmins, Ontario, about 400 miles north of Toronto.
Details are reported in the August 20-24 early edition of the Proceedings of the National Academy of Sciences.
Fabien Kenig, associate professor of earth and environmental sciences at the University of Illinois at Chicago, and his former doctoral student Gregory Ventura, spent nearly five years carefully analysing the shale samples, originally to compare what they found with an earlier Australian study suggesting the presence of eukaryotes some 2.7 billion years ago.
Ventura, now a post-doctoral researcher at the Woods Hole Oceanographic Institution, said initial laboratory results stunned him.

 "I thought there was something very wrong, that the samples were contaminated" - Gregory Ventura.

But Kenig was more confident they were on to something significant.
They didn't learn the true value of the material until it was analysed using a sophisticated, multi-dimensional gas chromatography instrument at the U.S. Coast Guard Academy.
When they analysed a sample, Kenig said, they were able to pull apart its complex mixture of molecular fossils, and found it was "essentially made of archaea-derived lipids."

The archaea lived in water and sediments when the region was covered by the sea. After burial, the archaea thrived where very hot water circulated in the rocks and where gold was deposited. Later, shale containing fossilised archaea got buried under thousands of feet of volcanic rock and sediments.
The researchers studied shale samples using a scanning electron microscope. They also analysed rock formation, mineral deposits and molecular fossils. Findings led the researchers to conclude that archaea and the other two life domains coexisted.

"Now we are sure the three domains of life were well separated and evolving (independently) by 2.7 billion years ago" -Fabien Kenig.

The finding broadens the known geographic reach of archaea during this time period, adding proof that the ancient organisms existed both in sedimentary environments and in subsurface hydrothermal settings.

"Considering the extent and composition of today's deep biosphere, it is likely that such hydrothermal subsurface communities have existed for much of the Earth's history"

Other collaborators in the study include Christopher Reddy of the Woods Hole Oceanographic Institution, Glenn Frysinger of the U.S. Coast Guard Academy, and Juergen Schieber, professor of geological sciences at Indiana University.
The project was supported by an exobiology grant from NASA

University of Illinois at Chicago

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Candidatus chloracidobacterium (Cab.) thermophilum
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In the hot springs of Yellowstone National Park, a team of researchers partially funded by the National Science Foundation (NSF) discovered a new bacterium that transforms light into chemical energy.
The discovery of the chlorophyll-producing bacterium, Candidatus chloracidobacterium (Cab.) thermophilum, is described in the July 27, 2007, issue of Science in a paper led by Don Bryant of Penn State University and David M. Ward of Montana State University.

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Candidatus Chloracidobacterium thermophilium
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A heat-loving bacterium that reveals a new way to harvest light energy has been discovered in the colourful microbial mats around the hot springs of Yellowstone National Park. For only the third time in 100 years, scientists have found a new group of bacteria that turns sunlight into chemical energy.

"This organism provides insights into the history of photosynthesis and increases our knowledge of how solar energy is captured in this microbial community. Thus, this bacterium may have implications for alternative fuels" - Dave Ward, a Montana State University professor who co-authored a scientific paper describing the bacterium.

The scientific paper will run Friday, July 27, in the journal, Science. The lead author, Don Bryant from The Pennsylvania State University, was a visiting scientist in MSU's Thermal Biology Institute during the summer of 2005. MSU co-authors are Ward, Christian Klatt and Mary Bateson; all in the Department of Land Resources and Environmental Sciences. Ward is also an adjunct professor in the Department of Microbiology.

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black chimney rock
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Ancient Matters Telling Life Origin
The research team headed by Prof. Li Jianghai of Peking University has recently found the so-called black chimney rock samples dated back to 2.5 billion years ago. These samples have gained the acknowledgement of the U.S. and Canadian scientists, which means scientific community has obtained the ancient matters to verify life origin.
The so-called black chimney is a pillar shaped vertical mound cumulated by sulphides such as pyrite, blend and brass. Surrounding the black chimney is the only habitat where self-support living creatures can grow and the hot fluid exhausted from the chimney may turn the ocean floor gas into biochemical energy.
Prof. Li believed that black chimney serves as natural lab for studying internal earth and life evolution and is of important impacts on global climate change, sea water chemistry and ocean heat balance. The obtained geological records of ancient black chimney are of important scientific and economic values. His team will analyse and test the rocks from different disciplinary angles so as to understand the earlier geological evolution of the oceans, look for relevant record on ancient life and test the scenarios such as that life originates from the adjacent areas of black chimneys on sea floor.
It is reported that a cross area sitting between Wutai Mount and Taihang Mount has preserved a complete geological record of such black chimneys which are made of sea floor sedimentary layer, sulphide cumulating for the formation of black chimneys, mineral fluid path and serpentinite. With complete rock types and intact structures, the black chimney will be of great values for unveiling the life origin and evolution in earlier oceans, earlier earth heat releasing mechanism and formation of metallic ores.

Source CHINA SCIENCE AND TECHNOLOGY NEWSLETTER 306 (Sept. 2002)

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Life on Earth Developed on Sea Floor
Researchers from Saint Louis University (SLU) and Peking University in China are revealing for the first time the findings of a discovery that could change the way we think about the development of life on Earth.
Two years ago, Timothy Kusky, Ph.D., the Paul C. Reinert Professor of Natural Sciences at SLU, and Jianghai Li, a professor of geological science at Peking University, dug up hundreds of fossilised black smoker chimneys in northern China.
Since then, the researchers have been analysing the samples in several laboratories. The discovery is important, the researchers say, because it lends support to the theory that life on the planet developed on the sea floor.
Findings the discovery are being reported in the latest issue of Gondwana Research, an international interdisciplinary journal published by Elsevier, the world's leading publisher of science and health information. It is featured as the journal's cover article.

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A Second Genesis -Did Early 'Alien' Microbial Life Co-Exist with Known Life?
One of the great outstanding scientific mysteries is the origin of life. How did it happen?
One Sunday in September, 1969 thousands of Australians were startled by a series of sonic booms and the sight of a fireball streaking from east to west across the sky before it exploded above the Goulburn Valley north of Melbourne. The fireball, later shown to be a rare carbonaceous meteorite, exploded into chunks and rained down on the small town of Murchison, where, amazingly, no one was injured.
The Murchison meteorite event was preceded two months earlier by the Apollo 11 mission and it's haul of moon rocks. Fortunately, the scientific community was prepared for the analysis of rocks of extraterrestrial origin.
The Murchison meteorite was found to be 4.5 million years old and packed with amino acids -some 74 types in all, eight of which are involved in the formation of earthly proteins. Thirty years later, scientists at NASA's Ames Research Centre discovered that the Murchison rock also harboured complex strings of sugars called polyols, which had never been found on Earth before.

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Extreme lifeform
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Scientists have long assumed that fungi exist mainly to decompose matter into chemicals that other organisms can then use. But researchers at the Albert Einstein College of Medicine of Yeshiva University have found evidence that fungi possess a previously undiscovered talent with profound implications: the ability to use radioactivity as an energy source for making food and spurring their growth.

"The fungal kingdom comprises more species than any other plant or animal kingdom, so finding that they're making food in addition to breaking it down means that Earth's energeticsin particular, the amount of radiation energy being converted to biological energymay need to be recalculated" - Dr. Arturo Casadevall, chair of microbiology & immunology at Einstein and senior author of the study, published May 23 in PLoS ONE.

The ability of fungi to live off radiation could also prove useful to people:

"Since ionising radiation is prevalent in outer space, astronauts might be able to rely on fungi as an inexhaustible food source on long missions or for colonizing other planets" - Dr. Ekaterina Dadachova, associate professor of nuclear medicine and microbiology & immunology at Einstein and lead author of the study.

Those fungi able to "eat" radiation must possess melanin, the pigment found in many if not most fungal species. But up until now, melanin's biological role in fungiif any--has been a mystery.

"Just as the pigment chlorophyll converts sunlight into chemical energy that allows green plants to live and grow, our research suggests that melanin can use a different portion of the electromagnetic spectrumionising radiationto benefit the fungi containing it" - Dr. Ekaterina Dadachova.

The research began five years ago when Dr. Casadevall read on the Web that a robot sent into the still-highly-radioactive damaged reactor at Chernobyl had returned with samples of black, melanin-rich fungi that were growing on the reactor's walls.

"I found that very interesting and began discussing with colleagues whether these fungi might be using the radiation emissions as an energy source" - Dr. Arturo Casadevall.

To test this idea, the Einstein researchers performed a variety of in vivo tests using three genetically diverse fungi and four measures of cell growth. The studies consistently showed that ionising radiation significantly enhances the growth of fungi that contain melanin.
For example, two types of fungi--one that was induced to make melanin (Crytococcus neoformans) and another that naturally contains it (Wangiella dermatitidis)were exposed to levels of ionising radiation approximately 500 times higher than background levels. Both species grew significantly faster (as measured by the number of colony forming units and dry weight) than when exposed to standard background radiation.
The researchers also carried out physico-chemical studies into melanin's ability to capture radiation. By measuring the electron spin resonance signal after melanin was exposed to ionising radiation, they showed that radiation interacts with melanin to alter its electron structure. This is an essential step for capturing radiation and converting it into a different form of energy to make food.
The melanin in fungi is no different chemically from the melanin in our skin.

"It's pure speculation but not outside the realm of possibility that melanin could be providing energy to skin cells. While it wouldn't be enough energy to fuel a run on the beach, maybe it could help you to open an eyelid"  - Dr. Arturo Casadevall.

Source

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One of the world's tiniest celebrities hails from one of the planet's toughest neighbourhoods.
Its story began a couple of years ago, when scientists fished a strange slime off a probe used to examine decades-old, high-level nuclear waste inside tanks stored at Savannah River Site.

"At first, nobody was sure what it was" - Christopher "Kitt" Bagwell, a senior scientist at the top-secret Savannah River National Laboratory.

Turns out, the greenish-orange slime was alive.

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New phylum of Archaea
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Jill Banfield, a scientist at the University of California, Berkeley, has been poking around in disused mines for more than 10 years, studying the microbes that inhabit these dark environs. Now, together with co-researcher Brett Baker, Banfield has discovered three new nano-sized microbes living amidst the more commonplace bacteria of the mine's interior. All three were so small - the size of large viruses - as to be virtually invisible under a microscope, and belonged to a totally new phylum of Archaea.

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The full family tree of the species known as social amoebas has been plotted for the first time – a breakthrough which will provide important clues to the evolution of life on earth.
Researchers, headed by evolutionary biologist Professor Sandie Baldauf, of the University of York, and biochemist Professor Pauline Schaap, of the University of Dundee, have produced the first molecular ‘dictionary’ of the 100 or so known species of social amoeba.
Using this family tree, they have devised a model system to establish how single cell organisms communicate and interact to create multi-cellular structures in response to changing environmental conditions. Previously, there was almost no molecular data for social amoeba – Dictyostelia – which are a hugely diverse and ancient group.
Social amoebas are a group of organisms with a genetic diversity that is greater than that of fungi and similar to that of all animals. They offer an excellent experimental system for studying aspects of evolution and communication that are not easy to study in more complex multi-cellular organisms.
The York and Dundee teams have worked with field biologists in Germany, the US and Japan, and their research is published today (Friday 27 October 2006) in the prestigious international journal Science.

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