April 17, 2011
In 2000, Roy Cullimore, a microbial ecologist and Charles Pellegrino, scientist and author of Ghosts of the Titanic discovered that the Titanic --which sank in the Atlantic Ocean 97 years ago -- was being devoured by a monster microbial industrial complex of extremophiles as alien we might expect to find on Jupiter's ocean-bound Europa. What they discovered is the largest, strangest cooperative microorganism on Earth.
Scientists believe that this strange super-organism is using a common microbial language that could be either chemical or electrical -a phenomenon called "quorum sensing" by which whole communities "sense" each other's presence and activities aiding and abetting the organization, cooperation, and growth.
The microbes are consuming the wreck's metal, creating mats of rust bigger than a dozen four-story brownstones that are creeping slowly along the hull harvesting iron from the rivets and burrowing into layers of steel plating. The creatures also leave behind "rusticles," 30-foot icicle-like deposits of rust dangling from the sides of the ship's bow. Structurally, rusticles contain channels to allow water to flow through, and they seem to be built up in a ring structure similar to the growth rings of a tree. They are very delicate and can easily disintegrate into fine powder on even the slightest touch.
These live mats and rusticles form a communicating super-organism funneling iron-rich fluids, sulfur, and electrical charges through the collective of archea, fungi, and bacteria that thrives in the icy dark, low oxygen waters. Using DNA technology, researchers discovered that the rusticles were formed by a combination of 27 different strains of bacteria. Among the bacteria feasting on the Titanic, there was a brand new member of the salt-loving Halomonas genus.
In June 2003, NOAA’s Office of Ocean Exploration sponsored an 11-day research cruise to the wreck site aboard the Russian Research Vessel Akademik Mstislav Keldysh. The vessel is equipped with two three-person submersibles (Mir I and Mir II) capable of diving to depths of 6,000 meters; the depth of the Titanic is 3,800 meters (12,467 feet).
OE planned four Mir dives to the Titanic to assess the wreck site in its current condition, and provide an opportunity to conduct scientific observations for ongoing research. Scientists from the United States and Canada were invited to participate in the expedition.
Larry Murphy, chief of the Submerged Resources Center, National Park Service, was on hand to provide archaeology assistance and advice. His expertise on metallic shipwrecks and site formation processes from the USS Arizona Memorial directly complements NOAA’s guidelines on Titanic. Dr. George Bass, known as the “father of maritime archaeology” from the Institute of Nautical Archaeology (INA), also joined the trip to offer archaeological expertise.
More than 24 hrs of annotated, on-site video data were acquired and catalogued, used to construct a photo mosaic of the wreck site, provide a context for site characteristics, and form a better understanding of site formation processes. The stern section of Titanic, which has largely been ignored in the past because it is in a jumbled state, was specifically analyzed.
The second objective of the expedition addressed microbial communities, the rusticles, that consume Titanic’s iron and cling to the wreck like rusty icicles. These features have been observed throughout the years. Ongoing qualitative analyses contribute to the scientific research regarding the ship’s degradation. Roy Cullimore and Lori Johnston from Droycon Bioconcepts, Inc. (DBI) of Canada organized the microbiological and rusticle observations.
A view of the bathtub in Capt. Smiths bathroom. Rusticles are observed growing over most of the pipes and fixtures in the room. Image courtesy of Lori Johnston, RMS Titanic Expedition 2003, NOAA-OE.
A 2003 expedition sent two Mir submersibles to survey the microbes that are infesting the ship and to determine their rate of growth. In 1998, four steel test platforms were placed in various locations near and on the wreck to assess the growth of rusticles on steel in different stages of fatigue. This expedition visited these platforms, and the video imagery revealed that all four showed strong evidence of rusticle growth. The longest rusticle extended 2.5 inches from the steel coupon.
One of the experiments conducted on this expedition was to see if a common species of surface-dwelling bacteria could survive exposure to the conditions at the Titanic site. In 1998, five species were sent to the site and survived for 18 hrs with losses of no more than one order of magnitude of cells. This year, the experiment was limited to one species of bacteria (Pseudomonas aeruginosa) with replication made possible using the BART reader system. This data showed that survivors from the dive (without any protection from the conditions at the site) were impacted to a varying degree, from no reduction of cell activity to less than one order of magnitude of reduction. One of the replicates showed three orders of magnitude reduction in cell activity.
Further observations were made on the deterioration of the bow and stern sections of Titanic. From these observations it appears that the stern section of the ship is deteriorating at a faster rate than the bow section, and has been calculated to be about 40 yrs ahead of the forward section. This was determined due to the state of the steel at the stern, which was severely embrittled and distorted, providing better "habitat" for rusticle formation. Also, because food was stored on Titanic primarily in the stern section of the ship, it supplied the initial nutrients for rusticle growth. Lastly, surfaces within the hull that had been torn apart served as a staging ground for rusticle growth.
See more: http://www.dailygalaxy.com/my_weblog/2011/04/gigantic-new-superorganism-with-social-intelligence-is-devouring-the-titanic-todays-most-popular.html
Showing posts with label microorganisms. Show all posts
Showing posts with label microorganisms. Show all posts
Friday, April 22, 2011
Thursday, May 20, 2010
'Artificial life' breakthrough announced by scientists
Thursday, 20 May 2010
By Victoria Gill
Science reporter, BBC News
Scientists in the US have succeeded in developing the first synthetic living cell.
The researchers constructed a bacterium's "genetic software" and transplanted it into a host cell.
The resulting microbe then looked and behaved like the species "dictated" by the synthetic DNA.
The advance, published in Science, has been hailed as a scientific landmark, but critics say there are dangers posed by synthetic organisms.
The researchers hope eventually to design bacterial cells that will produce medicines and fuels and even absorb greenhouse gases.
The team was led by Dr Craig Venter of the J Craig Venter Institute (JCVI) in Maryland and California.
He and his colleagues had previously made a synthetic bacterial genome, and transplanted the genome of one bacterium into another.
Now, the scientists have put both methods together, to create what they call a "synthetic cell", although only its genome is truly synthetic.
Dr Venter likened the advance to making new software for the cell.
The researchers copied an existing bacterial genome. They sequenced its genetic code and then used "synthesis machines" to chemically construct a copy.
Dr Venter told BBC News: "We've now been able to take our synthetic chromosome and transplant it into a recipient cell - a different organism.
"As soon as this new software goes into the cell, the cell reads [it] and converts into the species specified in that genetic code."
The new bacteria replicated over a billion times, producing copies that contained and were controlled by the constructed, synthetic DNA.
"This is the first time any synthetic DNA has been in complete control of a cell," said Dr Venter.
'New industrial revolution'
Dr Venter and his colleagues hope eventually to design and build new bacteria that will perform useful functions.
"I think they're going to potentially create a new industrial revolution," he said.
"If we can really get cells to do the production that we want, they could help wean us off oil and reverse some of the damage to the environment by capturing carbon dioxide."
Dr Venter and his colleagues are already collaborating with pharmaceutical and fuel companies to design and develop chromosomes for bacteria that would produce useful fuels and new vaccines.
But critics say that the potential benefits of synthetic organisms have been overstated.
Dr Helen Wallace from Genewatch UK, an organisation that monitors developments in genetic technologies, told BBC News that synthetic bacteria could be dangerous.
"If you release new organisms into the environment, you can do more harm than good," she said.
"By releasing them into areas of pollution, [with the aim of cleaning it up], you're actually releasing a new kind of pollution.
"We don't know how these organisms will behave in the environment."
Dr Wallace accused Dr Venter of playing down the potential drawbacks.
"He isn't God," she said, "he's actually being very human; trying to get money invested in his technology and avoid regulation that would restrict its use."
But Dr Venter said that he was "driving the discussions" about the regulations governing this relatively new scientific field and about the ethical implications of the work.
He said: "In 2003, when we made the first synthetic virus, it underwent an extensive ethical review that went all the way up to the level of the White House.
"And there have been extensive reviews including from the National Academy of Sciences, which has done a comprehensive report on this new field.
"We think these are important issues and we urge continued discussion that we want to take part in."
Ethical discussions
Dr Gos Micklem, a geneticist from the University of Cambridge, said that the advance was "undoubtedly a landmark" study.
But, he said, "there is already a wealth of simple, cheap, powerful and mature techniques for genetically engineering a range of organisms. Therefore, for the time being, this approach is unlikely to supplant existing methods for genetic engineering".
The ethical discussions surrounding the creation of synthetic or artificial life are set to continue.
Professor Julian Savulescu, from the Oxford Uehiro Centre for Practical Ethics at the University of Oxford, said the potential of this science was "in the far future, but real and significant".
"But the risks are also unparalleled," he continued. "We need new standards of safety evaluation for this kind of radical research and protections from military or terrorist misuse and abuse.
"These could be used in the future to make the most powerful bioweapons imaginable. The challenge is to eat the fruit without the worm."
The advance did not pose a danger in the form of bio-terrorism, Dr Venter said.
"That was reviewed extensively in the US in a report from Massachusetts Institute of Technology (MIT) and a Washington defence think tank, indicating that there were very small new dangers from this.
"Most people are in agreement that there is a slight increase in the potential for harm. But there's an exponential increase in the potential benefit to society," he told BBC's Newsnight.
"The flu vaccine you'll get next year could be developed by these processes," he added.
More at: http://news.bbc.co.uk/1/hi/science_and_environment/10132762.stm
By Victoria Gill
Science reporter, BBC News
Scientists in the US have succeeded in developing the first synthetic living cell.
The researchers constructed a bacterium's "genetic software" and transplanted it into a host cell.
The resulting microbe then looked and behaved like the species "dictated" by the synthetic DNA.
The advance, published in Science, has been hailed as a scientific landmark, but critics say there are dangers posed by synthetic organisms.
The researchers hope eventually to design bacterial cells that will produce medicines and fuels and even absorb greenhouse gases.
The team was led by Dr Craig Venter of the J Craig Venter Institute (JCVI) in Maryland and California.
He and his colleagues had previously made a synthetic bacterial genome, and transplanted the genome of one bacterium into another.
Now, the scientists have put both methods together, to create what they call a "synthetic cell", although only its genome is truly synthetic.
Dr Venter likened the advance to making new software for the cell.
The researchers copied an existing bacterial genome. They sequenced its genetic code and then used "synthesis machines" to chemically construct a copy.
Dr Venter told BBC News: "We've now been able to take our synthetic chromosome and transplant it into a recipient cell - a different organism.
"As soon as this new software goes into the cell, the cell reads [it] and converts into the species specified in that genetic code."
The new bacteria replicated over a billion times, producing copies that contained and were controlled by the constructed, synthetic DNA.
"This is the first time any synthetic DNA has been in complete control of a cell," said Dr Venter.
'New industrial revolution'
Dr Venter and his colleagues hope eventually to design and build new bacteria that will perform useful functions.
"I think they're going to potentially create a new industrial revolution," he said.
"If we can really get cells to do the production that we want, they could help wean us off oil and reverse some of the damage to the environment by capturing carbon dioxide."
Dr Venter and his colleagues are already collaborating with pharmaceutical and fuel companies to design and develop chromosomes for bacteria that would produce useful fuels and new vaccines.
But critics say that the potential benefits of synthetic organisms have been overstated.
Dr Helen Wallace from Genewatch UK, an organisation that monitors developments in genetic technologies, told BBC News that synthetic bacteria could be dangerous.
"If you release new organisms into the environment, you can do more harm than good," she said.
"By releasing them into areas of pollution, [with the aim of cleaning it up], you're actually releasing a new kind of pollution.
"We don't know how these organisms will behave in the environment."
Dr Wallace accused Dr Venter of playing down the potential drawbacks.
"He isn't God," she said, "he's actually being very human; trying to get money invested in his technology and avoid regulation that would restrict its use."
But Dr Venter said that he was "driving the discussions" about the regulations governing this relatively new scientific field and about the ethical implications of the work.
He said: "In 2003, when we made the first synthetic virus, it underwent an extensive ethical review that went all the way up to the level of the White House.
"And there have been extensive reviews including from the National Academy of Sciences, which has done a comprehensive report on this new field.
"We think these are important issues and we urge continued discussion that we want to take part in."
Ethical discussions
Dr Gos Micklem, a geneticist from the University of Cambridge, said that the advance was "undoubtedly a landmark" study.
But, he said, "there is already a wealth of simple, cheap, powerful and mature techniques for genetically engineering a range of organisms. Therefore, for the time being, this approach is unlikely to supplant existing methods for genetic engineering".
The ethical discussions surrounding the creation of synthetic or artificial life are set to continue.
Professor Julian Savulescu, from the Oxford Uehiro Centre for Practical Ethics at the University of Oxford, said the potential of this science was "in the far future, but real and significant".
"But the risks are also unparalleled," he continued. "We need new standards of safety evaluation for this kind of radical research and protections from military or terrorist misuse and abuse.
"These could be used in the future to make the most powerful bioweapons imaginable. The challenge is to eat the fruit without the worm."
The advance did not pose a danger in the form of bio-terrorism, Dr Venter said.
"That was reviewed extensively in the US in a report from Massachusetts Institute of Technology (MIT) and a Washington defence think tank, indicating that there were very small new dangers from this.
"Most people are in agreement that there is a slight increase in the potential for harm. But there's an exponential increase in the potential benefit to society," he told BBC's Newsnight.
"The flu vaccine you'll get next year could be developed by these processes," he added.
More at: http://news.bbc.co.uk/1/hi/science_and_environment/10132762.stm
Wednesday, February 3, 2010
New Research Rejects 80-Year Theory of 'Primordial Soup' as the Origin of Life
ScienceDaily (Feb. 3, 2010) — For 80 years it has been accepted that early life began in a 'primordial soup' of organic molecules before evolving out of the oceans millions of years later. Today the 'soup' theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth's chemical energy, from hydrothermal vents on the ocean floor, which kick-started early life.
"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won't work at all," said team leader Dr Nick lane from University College London. "We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent -- one that is riddled with tiny interconnected compartments or pores."
The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.
"Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life," said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. "But soup has no capacity for producing the energy vital for life."
In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides which may have given rise to the first true cells.
The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today -- a gradient of protons over a membrane. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO2.
"Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation -- positive outside and negative inside -- as the inorganic vesicles from which they arose" said co-author John Allen, a biochemist at Queen Mary, University of London.
"Thermodynamic constraints mean that chemiosmosis is strictly necessary for carbon and energy metabolism in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells," said Lane. "Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own."
This was a vital transition, as chemiosmosis is the only mechanism by which organisms could escape from the vents. "The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved -- and they could not have evolved without it," said Martin.
"Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis," concluded Lane. "It is time to cast off the shackles of fermentation in some primordial soup as 'life without oxygen' -- an idea that dates back to a time before anybody in biology had any understanding of how ATP is made."
http://www.sciencedaily.com/releases/2010/02/100202101245.htm
(Submitted by Tim Chapman)
"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won't work at all," said team leader Dr Nick lane from University College London. "We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent -- one that is riddled with tiny interconnected compartments or pores."
The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.
"Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life," said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. "But soup has no capacity for producing the energy vital for life."
In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides which may have given rise to the first true cells.
The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today -- a gradient of protons over a membrane. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO2.
"Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation -- positive outside and negative inside -- as the inorganic vesicles from which they arose" said co-author John Allen, a biochemist at Queen Mary, University of London.
"Thermodynamic constraints mean that chemiosmosis is strictly necessary for carbon and energy metabolism in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells," said Lane. "Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own."
This was a vital transition, as chemiosmosis is the only mechanism by which organisms could escape from the vents. "The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved -- and they could not have evolved without it," said Martin.
"Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis," concluded Lane. "It is time to cast off the shackles of fermentation in some primordial soup as 'life without oxygen' -- an idea that dates back to a time before anybody in biology had any understanding of how ATP is made."
http://www.sciencedaily.com/releases/2010/02/100202101245.htm
(Submitted by Tim Chapman)
Astrobiologist Claims Life on Earth Seeded by Comets
bbc - New evidence from astrobiology "overwhelmingly" supports the view that life was seeded from outside Earth, a scientist has claimed.
Prof Chandra Wickramasinghe of Cardiff University says the first microbes were deposited on Earth 3,800m years ago.
The astrobiologist has helped developed the panspermia theory which suggests an extra-terrestrial origin for life.
He argues for a cycle of life as microbes find their way into comets and "multiply and seed other planets".
In the article, published in the International Journal of Astrobiology, Monday, he argues humans and indeed all life on Earth is of alien origin, brought onto the planet by comets hitting the planet.
Prof Wickramasinghe, of Cardiff University's centre for astrobiology, says there is a cyclical transfer process of life from planet to planet.
He believes comets hit planets and push living organic matter out into space, some of which survives and in turn gets transferred to developing planetary systems over a timescale of millions and millions of years, seeding life on the newly formed planets.
He accepts this model still does not explain how life actually began in the first place, but says there is no hard evidence to support the theory that life only began in a "primordial soup" on Earth, or other places.
Over the past three decades research has shown that large swathes of the Milky Way are strewn with gigantic dust clouds full of organic molecules, which some people have argued shows life emerging independently from new in these clouds.
In his paper, he says recent interpretation of spectra readings from the organic molecules found in interstellar clouds has indicated that they are in fact the remains of bacteria which has been broken down, rather than being built up.
"Interstellar clouds appear to be the graveyard of life not its cradle," he said.
"Each time a new planetary system forms a few surviving microbes find their way into comets. These then multiply and seed other planets," he said.
He adds: "We are thus part of a connected chain of being that extends over a large volume of the cosmos. Evidence is pointing inexorably in this direction."
The professor and his late colleague Sir Fred Hoyle championed the panspermia theory from the 1960s.
http://naturalplane.blogspot.com/2010/02/astrobiologist-claims-life-on-earth.html
(Submitted by T. Peter Park)
See also: http://news.bbc.co.uk/1/hi/wales/south_east/8491398.stm
Prof Chandra Wickramasinghe of Cardiff University says the first microbes were deposited on Earth 3,800m years ago.
The astrobiologist has helped developed the panspermia theory which suggests an extra-terrestrial origin for life.
He argues for a cycle of life as microbes find their way into comets and "multiply and seed other planets".
In the article, published in the International Journal of Astrobiology, Monday, he argues humans and indeed all life on Earth is of alien origin, brought onto the planet by comets hitting the planet.
Prof Wickramasinghe, of Cardiff University's centre for astrobiology, says there is a cyclical transfer process of life from planet to planet.
He believes comets hit planets and push living organic matter out into space, some of which survives and in turn gets transferred to developing planetary systems over a timescale of millions and millions of years, seeding life on the newly formed planets.
He accepts this model still does not explain how life actually began in the first place, but says there is no hard evidence to support the theory that life only began in a "primordial soup" on Earth, or other places.
Over the past three decades research has shown that large swathes of the Milky Way are strewn with gigantic dust clouds full of organic molecules, which some people have argued shows life emerging independently from new in these clouds.
In his paper, he says recent interpretation of spectra readings from the organic molecules found in interstellar clouds has indicated that they are in fact the remains of bacteria which has been broken down, rather than being built up.
"Interstellar clouds appear to be the graveyard of life not its cradle," he said.
"Each time a new planetary system forms a few surviving microbes find their way into comets. These then multiply and seed other planets," he said.
He adds: "We are thus part of a connected chain of being that extends over a large volume of the cosmos. Evidence is pointing inexorably in this direction."
The professor and his late colleague Sir Fred Hoyle championed the panspermia theory from the 1960s.
http://naturalplane.blogspot.com/2010/02/astrobiologist-claims-life-on-earth.html
(Submitted by T. Peter Park)
See also: http://news.bbc.co.uk/1/hi/wales/south_east/8491398.stm
Thursday, June 18, 2009
Microbiologists find magnetic bacteria in Lonar lake
Microbiologists in Maharashtra have found 'magnetic bacteria' in the ancient Lonar lake formed due to meteorite impact, a finding that might open a vista for searching extra-terrestrial life.The magnetotactic bacteria, which are object of interest of scientists from various fields world over, were isolated from the lake in Maharashtra's Buldana district which is the only impact crater formed in basaltic rock.
The bacteria are unique as they swim along geomagnetic field lines because they contain tiny magnetic crystals called magnetosomes, said Mahesh Chavadar, a microbiologist at the Yashwantrao Chavan College of Science in Karad.The fact that the bacteria was found in the lake has thrown open doors for research on life outside universe.
"This seems to hint at a certain correlation between these bacteria and meteorites, and that could have tremendous implications on the search for extra-terrestrial life. We need to explore if life outside the earth existed in this form," Chavadar said reporting his findings in a recent issue of 'Current Science'.
The bacteria was first discovered in 1975 and only a few cultures of the micro-organisms are available in laboratories across the world.Chavadar said scientists have found that magnetic nano-crystals in Martian meteorite ALH84001 were similar to bacterial magnetosomes. The meteorite dating back to 4.5 billion years was found in Antarctica in 1984.In light of the ecological importance of magnetic bacteria in bio-geochemical cycles, their study in hitherto unexplored environments can be significant.The magnetotactic bacteria have the ability to orient and migrate or swim along geomagnetic field lines, a behaviour referred to as magnetoaxis.This property is based on specific intracellular structures -- the magnetosomes -- which are tiny magnetic crystals composed of iron minerals.The presence of magnetosomes in the bacteria was confirmed by measuring their iron content which was found to be much greater than the nonmagnetic cultures."Intracellular iron accumulation studies on these bacteria showed up to 11.5 times more iron than non-magnetic bacteria," Chavadar said.
Wednesday, March 11, 2009
Texas-sized tract of single-celled clones
Biologists find world-record colony of amoebae in Houston cow pasture
HOUSTON -- (March 11, 2009) -- A Rice University study of microbes from a Houston-area cow pasture has confirmed once again that everything is bigger in Texas, even the single-celled stuff. The tests revealed the first-ever report of a large, natural colony of amoebae clones -- a Texas-sized expanse measuring at least 12 meters across.
The research is available online and featured on cover of the March issue of Molecular Ecology.
This is the Houston pasture where the amoeba colony was found.
Credit: O. Gilbert/Rice University
Some large organisms like aspen trees and sea anemones are well-known for growing in large clonal colonies. For example, one colony of aspen clones in Utah contains more than 40,000 trees that share a massive root system.
In contrast, the short-lived patch of amoeba clones contained millions of genetically identical individuals of the species Dictyostelium discoideum. Though they typically live as loners, hunting and eating bacteria, D. discoideum are known to cooperate when food gets scarce and even to sacrifice their lives altruistically. Biologists say the discovery of the clonal colony could yield important clues about the evolution of such cooperative behavior.
"This discovery is important for our understanding of microbial social evolution because the processes of selection, cooperation and competition play out differently when populations are geographically mixed as opposed to being isolated in patches," said study co-author Joan Strassmann, the Harry C. and Olga K. Wiess Professor in Natural Sciences and chair of Rice's Department of Ecology and Evolutionary Biology.
Studies of clonal colonies in other species show that the colonies often appear at the edge of a species' natural range.
D. discoideum cooperate to form stalks topped with "fruiting bodies."
Credit: O. Gilbert/Rice University
"People had seen this in studies of sea anemone and other species," said study co-author Owen Gilbert, a Rice graduate student in ecology and evolutionary biology. "There are thought to be two ways that these colonies can form at the edge of a species' natural range: either just one clone finds its way there, or perhaps a few make it there but they compete with each other and just one wins out."
Based on these studies, Strassmann, Gilbert and co-author and evolutionary biologist David Queller, Rice's Harry C. and Olga K. Wiess Professor of Ecology and Evolutionary Biology, surmised that clonal patches could form on the edge of a microbial species' range, and they looked for a suitable location to test the idea in D. discoideum.
"D. discoideum tends to thrive at higher altitudes and in densely wooded areas where the soil stays moist," Gilbert said. "A Texas cattle pasture is simply the wrong type of habitat. But D. discoideum thrives on the dung of various animals, which suggests that given a good amount of rain, a cattle pasture could be the perfect place for a population explosion."
Strassmann, Gilbert and a team of Rice undergraduate researchers took samples from 18 local pastures. In each, they plotted a grid and collected soil and dung samples. Back at the lab, they put the samples on clear plates and examined them daily to see whether they produced any feeding amoebae. When amoebae were found, they were analyzed genetically to see whether they were the same species, and if so, whether they were genetic clones.
In one of the fields, they found that all the D. discoideum samples were genetic clones. Subsequent tests in the lab showed that the strain didn't have a distinct competitive advantage over three other strains found in nearby pastures. Exactly how and why the large clonal patch appeared in that particular field isn't clear, but the fact that it was there raises some intriguing questions.
For example, Strassmann and Queller's prior work with D. discoideum has turned up more than 100 genes that help the organism regulate its cooperative behavior. They also know that mutations to these genes can allow individual amoebae to "cheat" and take advantage of nonmutants' willingness to sacrifice themselves. How species like D. discoideum manage to keep cheaters from out-producing and eliminating cooperative strains is one focus of their work.
"The existence of clonal patches in microbial species presents very interesting possibilities for the appearance and regulation of cheating behaviors," Queller said. "It is likely that additional natural studies of social microbes will continue to complement the genetic and evolutionary laboratory studies of these organisms."
###
The research was supported by a grant from the National Science Foundation, a Wray-Todd Graduate Fellowship and a Houston Livestock Show and Rodeo Scholarship.
http://www.eurekalert.org/pub_releases/2009-03/ru-tto031109.php
HOUSTON -- (March 11, 2009) -- A Rice University study of microbes from a Houston-area cow pasture has confirmed once again that everything is bigger in Texas, even the single-celled stuff. The tests revealed the first-ever report of a large, natural colony of amoebae clones -- a Texas-sized expanse measuring at least 12 meters across.
The research is available online and featured on cover of the March issue of Molecular Ecology.
Credit: O. Gilbert/Rice University
Some large organisms like aspen trees and sea anemones are well-known for growing in large clonal colonies. For example, one colony of aspen clones in Utah contains more than 40,000 trees that share a massive root system.
In contrast, the short-lived patch of amoeba clones contained millions of genetically identical individuals of the species Dictyostelium discoideum. Though they typically live as loners, hunting and eating bacteria, D. discoideum are known to cooperate when food gets scarce and even to sacrifice their lives altruistically. Biologists say the discovery of the clonal colony could yield important clues about the evolution of such cooperative behavior.
"This discovery is important for our understanding of microbial social evolution because the processes of selection, cooperation and competition play out differently when populations are geographically mixed as opposed to being isolated in patches," said study co-author Joan Strassmann, the Harry C. and Olga K. Wiess Professor in Natural Sciences and chair of Rice's Department of Ecology and Evolutionary Biology.
Studies of clonal colonies in other species show that the colonies often appear at the edge of a species' natural range.
Credit: O. Gilbert/Rice University
"People had seen this in studies of sea anemone and other species," said study co-author Owen Gilbert, a Rice graduate student in ecology and evolutionary biology. "There are thought to be two ways that these colonies can form at the edge of a species' natural range: either just one clone finds its way there, or perhaps a few make it there but they compete with each other and just one wins out."
Based on these studies, Strassmann, Gilbert and co-author and evolutionary biologist David Queller, Rice's Harry C. and Olga K. Wiess Professor of Ecology and Evolutionary Biology, surmised that clonal patches could form on the edge of a microbial species' range, and they looked for a suitable location to test the idea in D. discoideum.
"D. discoideum tends to thrive at higher altitudes and in densely wooded areas where the soil stays moist," Gilbert said. "A Texas cattle pasture is simply the wrong type of habitat. But D. discoideum thrives on the dung of various animals, which suggests that given a good amount of rain, a cattle pasture could be the perfect place for a population explosion."
Strassmann, Gilbert and a team of Rice undergraduate researchers took samples from 18 local pastures. In each, they plotted a grid and collected soil and dung samples. Back at the lab, they put the samples on clear plates and examined them daily to see whether they produced any feeding amoebae. When amoebae were found, they were analyzed genetically to see whether they were the same species, and if so, whether they were genetic clones.
In one of the fields, they found that all the D. discoideum samples were genetic clones. Subsequent tests in the lab showed that the strain didn't have a distinct competitive advantage over three other strains found in nearby pastures. Exactly how and why the large clonal patch appeared in that particular field isn't clear, but the fact that it was there raises some intriguing questions.
For example, Strassmann and Queller's prior work with D. discoideum has turned up more than 100 genes that help the organism regulate its cooperative behavior. They also know that mutations to these genes can allow individual amoebae to "cheat" and take advantage of nonmutants' willingness to sacrifice themselves. How species like D. discoideum manage to keep cheaters from out-producing and eliminating cooperative strains is one focus of their work.
"The existence of clonal patches in microbial species presents very interesting possibilities for the appearance and regulation of cheating behaviors," Queller said. "It is likely that additional natural studies of social microbes will continue to complement the genetic and evolutionary laboratory studies of these organisms."
###
The research was supported by a grant from the National Science Foundation, a Wray-Todd Graduate Fellowship and a Houston Livestock Show and Rodeo Scholarship.
http://www.eurekalert.org/pub_releases/2009-03/ru-tto031109.php
Monday, February 23, 2009
Life Forms May Have Evolved In Ancient Hot Springs On Mars
ScienceDaily (Feb. 21, 2009) — Data from the Mars Reconnaissance Orbiter (MRO) suggest the discovery of ancient springs in the Vernal Crater, sites where life forms may have evolved on Mars, according to a new report.
Hot springs have great astrobiological significance, as the closest relatives of many of the most ancient organisms on Earth can thrive in and around hydrothermal springs. If life forms have ever been present on Mars, hot spring deposits would be ideal locations to search for physical or chemical evidence of these organisms and could be target areas for future exploratory missions.
Carlton C. Allen and Dorothy Z. Oehler, from the Astromaterials Research and Exploration Science Directorate at the NASA Johnson Space Center, Houston, Texas, propose that new image data from the High Resolution Imaging Science Experiment (HiRISE) on MRO depict structures in Vernal Crater that appear to have arisen as part of a major area of ancient spring activity. The data suggest that the southern part of Vernal Crater has experienced episodes of water flow from underground to the surface and may be a site where martian life could have developed.
"Hot spring deposits are key target areas for future Mars missions," says Sherry L. Cady, PhD, Editor of Astrobiology and Associate Professor in the Department of Geology at Portland State University.
"Such deposits on Earth preserve evidence of the fossilized remains of the microbial communities that inhabited the hot springs over a wide range of spatial scales. The potential to find key evidence indicative of life––biofabrics, microbial remains, chemical fossils in minerals––is high when sedimentary deposits form from hydrothermal fluids. Hot spring fluids are typically laden with dissolved mineral ions that, when they precipitate out and create the hydrothermal deposit, enhance fossilization of all types of biosignatures."
-----
Journal reference:
Carlton C. Allen and Dorothy Z. Oehler. A Case for Ancient Springs in Arabia Terra, Mars. Astrobiology, 2008; 8 (6): 1093 DOI: 10.1089/ast.2008.0239
Adapted from materials provided by Mary Ann Liebert, Inc./Genetic Engineering News, via EurekAlert!, a service of AAAS.
http://www.sciencedaily.com/releases/2009/02/090212112829.htm
Hot springs have great astrobiological significance, as the closest relatives of many of the most ancient organisms on Earth can thrive in and around hydrothermal springs. If life forms have ever been present on Mars, hot spring deposits would be ideal locations to search for physical or chemical evidence of these organisms and could be target areas for future exploratory missions.
Carlton C. Allen and Dorothy Z. Oehler, from the Astromaterials Research and Exploration Science Directorate at the NASA Johnson Space Center, Houston, Texas, propose that new image data from the High Resolution Imaging Science Experiment (HiRISE) on MRO depict structures in Vernal Crater that appear to have arisen as part of a major area of ancient spring activity. The data suggest that the southern part of Vernal Crater has experienced episodes of water flow from underground to the surface and may be a site where martian life could have developed.
"Hot spring deposits are key target areas for future Mars missions," says Sherry L. Cady, PhD, Editor of Astrobiology and Associate Professor in the Department of Geology at Portland State University.
"Such deposits on Earth preserve evidence of the fossilized remains of the microbial communities that inhabited the hot springs over a wide range of spatial scales. The potential to find key evidence indicative of life––biofabrics, microbial remains, chemical fossils in minerals––is high when sedimentary deposits form from hydrothermal fluids. Hot spring fluids are typically laden with dissolved mineral ions that, when they precipitate out and create the hydrothermal deposit, enhance fossilization of all types of biosignatures."
-----
Journal reference:
Carlton C. Allen and Dorothy Z. Oehler. A Case for Ancient Springs in Arabia Terra, Mars. Astrobiology, 2008; 8 (6): 1093 DOI: 10.1089/ast.2008.0239
Adapted from materials provided by Mary Ann Liebert, Inc./Genetic Engineering News, via EurekAlert!, a service of AAAS.
http://www.sciencedaily.com/releases/2009/02/090212112829.htm
Controversy Over World’s Oldest Traces Of Life
ScienceDaily (Feb. 16, 2009) — The argument over whether an outcrop of rock in South West Greenland contains the earliest known traces of life on Earth has been reignited, in a study to be published in the Journal of the Geological Society on 23 February. The research, led by Martin J. Whitehouse at the Swedish Museum of Natural History, argues that the controversial rocks ‘cannot host evidence of Earth’s oldest life’, reopening the debate over where the oldest traces of life are located.
The small island of Akilia has long been the centre of attention for scientists looking for early evidence of life. Research carried out in 1996 argued that a five metre wide outcrop of rock on the island contained graphite with depleted levels of 13C. Carbon isotopes are frequently used to search for evidence of early life, because the lightest form of carbon, 12C (atomic weight 12), is preferred in biological processes as it requires less energy to be used by organisms. This results in heavier forms, such as 13C, being less concentrated, which might account for the depleted levels found in the rocks at Akilia.
Crucial to the dating of these traces was analysing the cross-cutting intrusions made by igneous rocks into the outcrop. Whatever is cross-cut must be older than the intruding rocks, so obtaining a date for the intrusive rock was vital. When these were claimed to be at least 3.85 billion years old, it seemed that Akilia did indeed hold evidence of the oldest traces of life on Earth.
Since then, many critics have cast doubt on the findings. Over billions of years, the rocks have undergone countless changes to their structure, being folded, distorted, heated and compressed to such an extent that their mineral composition is very different now to what it was originally. The dating of the intrusive rock has also been questioned .Nevertheless, in July 2006, an international team of scientists, led by Craig E. Manning at UCLA, published a paper claiming that they had proved conclusively that the traces of life were older than 3.8 billion years, after having mapped the area extensively. They argued that the rocks formed part of a volcanic stratigraphy, with igneous intrusions, using the cross-cutting relationships between the rocks as an important part of their theory.
The new research, led by Martin J. Whitehouse at the Swedish Museum of Natural History and Nordic Center for Earth Evolution, casts doubt on this interpretation. The researchers present new evidence demonstrating that the cross-cutting relationships are instead caused by tectonic activity, and represent a deformed fault or unconformity. If so, the age of the intrusive rock is irrelevant to the dating of the graphite, and it could well be older. Because of this, the scientists turned their attention to dating the graphite-containing rocks themselves, and found no evidence that they are any older than c. 3.67 billion years.
‘The rocks of Akilia provide no evidence that life existed at or before c. 3.82 Ga, or indeed before 3.67 Ga’, they conclude.
The age of the Earth itself is around 4.5 billion years. If life complex enough to have the ability to fractionate carbon were to exist at 3.8 billion years, this would suggest life originated even earlier. The Hadean eon, 3.8 – 4.5 billion years ago, is thought to have been an environment extremely hostile to life. In addition to surviving this period, such early life would have had to contend with the ‘Late Heavy Bombardment’ between 3.8 and 4.1 billion years ago, when a large number of impact craters on the Moon suggest that both the Earth and the Moon underwent significant bombardment, probably by collision with asteroids.
-----
Journal reference:
M J Whitehouse, J S Myers & C M Fedo. The Akilia Controversy: field, structural and geochronological evidence questions interpretations of >3.8 Ga life in SW Greenland. Journal of the Geological Society, Vol. 166, 2009, pp. 1-14
Adapted from materials provided by Geological Society of London, via AlphaGalileo.
The small island of Akilia has long been the centre of attention for scientists looking for early evidence of life. Research carried out in 1996 argued that a five metre wide outcrop of rock on the island contained graphite with depleted levels of 13C. Carbon isotopes are frequently used to search for evidence of early life, because the lightest form of carbon, 12C (atomic weight 12), is preferred in biological processes as it requires less energy to be used by organisms. This results in heavier forms, such as 13C, being less concentrated, which might account for the depleted levels found in the rocks at Akilia.
Crucial to the dating of these traces was analysing the cross-cutting intrusions made by igneous rocks into the outcrop. Whatever is cross-cut must be older than the intruding rocks, so obtaining a date for the intrusive rock was vital. When these were claimed to be at least 3.85 billion years old, it seemed that Akilia did indeed hold evidence of the oldest traces of life on Earth.
Since then, many critics have cast doubt on the findings. Over billions of years, the rocks have undergone countless changes to their structure, being folded, distorted, heated and compressed to such an extent that their mineral composition is very different now to what it was originally. The dating of the intrusive rock has also been questioned .Nevertheless, in July 2006, an international team of scientists, led by Craig E. Manning at UCLA, published a paper claiming that they had proved conclusively that the traces of life were older than 3.8 billion years, after having mapped the area extensively. They argued that the rocks formed part of a volcanic stratigraphy, with igneous intrusions, using the cross-cutting relationships between the rocks as an important part of their theory.
The new research, led by Martin J. Whitehouse at the Swedish Museum of Natural History and Nordic Center for Earth Evolution, casts doubt on this interpretation. The researchers present new evidence demonstrating that the cross-cutting relationships are instead caused by tectonic activity, and represent a deformed fault or unconformity. If so, the age of the intrusive rock is irrelevant to the dating of the graphite, and it could well be older. Because of this, the scientists turned their attention to dating the graphite-containing rocks themselves, and found no evidence that they are any older than c. 3.67 billion years.
‘The rocks of Akilia provide no evidence that life existed at or before c. 3.82 Ga, or indeed before 3.67 Ga’, they conclude.
The age of the Earth itself is around 4.5 billion years. If life complex enough to have the ability to fractionate carbon were to exist at 3.8 billion years, this would suggest life originated even earlier. The Hadean eon, 3.8 – 4.5 billion years ago, is thought to have been an environment extremely hostile to life. In addition to surviving this period, such early life would have had to contend with the ‘Late Heavy Bombardment’ between 3.8 and 4.1 billion years ago, when a large number of impact craters on the Moon suggest that both the Earth and the Moon underwent significant bombardment, probably by collision with asteroids.
-----
Journal reference:
M J Whitehouse, J S Myers & C M Fedo. The Akilia Controversy: field, structural and geochronological evidence questions interpretations of >3.8 Ga life in SW Greenland. Journal of the Geological Society, Vol. 166, 2009, pp. 1-14
Adapted from materials provided by Geological Society of London, via AlphaGalileo.
Friday, February 20, 2009
Alien life 'may exist among us'
By James Morgan
Science reporter, BBC News, Chicago
Never mind Mars, alien life may be thriving right here on Earth, a major science conference has heard.
Our planet may harbour forms of "weird life" unrelated to life as we know it, according to Professor Paul Davies, a physicist at Arizona State University.
This "shadow life" may be hidden in toxic arsenic lakes or in boiling deep sea hydrothermal vents, he says.
He has called on scientists to launch a "mission to Earth" by trawling hostile environments for signs of bio-activity.
Weird life could even be living among us, in forms which we don't yet recognise, he told the American Association for the Advancement of Science (AAAS) meeting in Chicago.
"We don't have to go to other planets to find weird life.
"It could be right in front of our noses - or even in our noses," said the physicist.
"It is entirely reasonable to expect we will find a shadow biosphere here on Earth.
"But nobody has actually taken the trouble to look.
"The question is why? The cost is not expensive - it would be a fraction of the money we spend searching for extraterrestrial life."
'Second genesis'
Professor Davies was one of the speakers at a symposium exploring the possibility that life has evolved on Earth more than once.
The descendants of this "second genesis" may have survived until today in a "shadow biosphere" which is beyond our radar because its inhabitants have biochemistry so different from our own.
"All our microscopes are customised for life as we know it - so it's no surprise that we haven't found microbes with different biochemistry," said Professor Davies.
"We don't quite know how weird life would look. It's as wide as the imagination and that's why it's really hard to look for."
If it exists, weird life could be based on DNA and RNA - but with a slightly different genetic code or different amino acids.
At the other end of the spectrum, we could find creatures which have more drastic differences.
"Maybe one of the elements life uses - carbon, hydrogen, oxygen, nitrogen, phosphorus - could be replaced by something else," said Professor Davies.
"When I say that, everyone immediately thinks of silicon life - because of Star Trek. But I'm not talking about anything that drastic.
"For example, most of the jobs that can be done by phosphorus can be done by arsenic."
Arsenic may be poisonous to humans, but it has chemical properties which might make it ideal in a microbe's machinery, he said.
'Mission to Earth'
So how do we go about hunting for something we have never seen before?
"There are two possibilities," said Prof Davies, Director of the BEYOND Center for Fundamental Concepts in Science.
"One is that weird life is ecologically isolated, in niches beyond the reach of mankind."
In this case, we must begin trawling the world's most inhospitable environments - deserts, salt lakes, and areas of high pressure, temperature or UV radiation.
"We could have a 'mission to Earth'. There's a big long list of places we could be looking," observed Professor Davies.
"For example, if we are looking for arsenic life, we could head for environments which are both arsenic rich and phosphorus poor - such as deep ocean vents.
"There is also a heavily contaminated lake in California which is arsenic rich - Mono Lake - and we do find microbes in there which get their energy from arsenic.
"But they don't actually incorporate the arsenic into themselves. They spit it back out again. They smoke but they don't inhale."
On the other hand, it could be that "weird life" is actually all around us - intermingled with carbon based life.
"In that case it's going to be really hard to detect - you have to find some way of filtering everything else out."
This laborious process has been used to search for unknown organisms in seawater - by painstakingly filtering everything else away.
If we did discover something unprecedented, "we'd all start arguing" said Professor Davies, a theoretical physicist.
"The question would be whether this life was truly different, or whether there was a common precursor a deep branch on the main tree of life.
"Also, how do we know we are dealing with separate Earth genesis and not a Mars genesis?
"We know rocks do get traded between the two planets, and life could hitch a ride.
"Personally, I'm only interested in establishing whether life happened more than once. If we find it has happened twice from scratch then its going to have happened all around the universe.
"It's going to be teeming with life and there's a very good chance we are not alone."
Life in the lab
Another way to determine what alternative life might look like is to try to invent it ourselves.
If we can create new molecules which can behave in life-like way, we may then go out and look for these in the environment, says Professor Steven Benner, of the University of Florida.
His team have created perhaps the closest yet to a man-made alternative form of life.
"We are announcing the first example of an artificial synthetic chemical system capable of Darwinian evolution," he told the conference.
"Is it alive? Well, I can tell you that it is not self-sustaining.
"You have to have a graduate student stand there and feed it from time to time, but it is evolving."
The molecule is essentially a modified version of our own DNA double helix - but with six "letters" in its genetic alphabet, instead of four.
These nucleotides pair up in strands, which can replicate, though only with the help of polymerase enzymes and heat.
"Sometimes mistakes are made in pairing and these mistakes are maintained in the next generation - it is evolving," said Prof Brenner.
"The next step is to apply natural selection to it, to see if it can evolve under selective pressure.
"The accepted definition of life is a molecule capable of Darwinian evolution, so we are trying to put together molecules that are capable of doing it."
But he questioned whether our definition of "living" is perhaps too "Earth-centric".
"Remember - just because you are a chemical system which is self-sustaining and capable of Darwinian evolution, that doesn't mean that is the universal definition of life," he said.
http://news.bbc.co.uk/1/hi/sci/tech/7893414.stm
Science reporter, BBC News, Chicago
Never mind Mars, alien life may be thriving right here on Earth, a major science conference has heard.
Our planet may harbour forms of "weird life" unrelated to life as we know it, according to Professor Paul Davies, a physicist at Arizona State University.
This "shadow life" may be hidden in toxic arsenic lakes or in boiling deep sea hydrothermal vents, he says.
He has called on scientists to launch a "mission to Earth" by trawling hostile environments for signs of bio-activity.
Weird life could even be living among us, in forms which we don't yet recognise, he told the American Association for the Advancement of Science (AAAS) meeting in Chicago.
"We don't have to go to other planets to find weird life.
"It could be right in front of our noses - or even in our noses," said the physicist.
"It is entirely reasonable to expect we will find a shadow biosphere here on Earth.
"But nobody has actually taken the trouble to look.
"The question is why? The cost is not expensive - it would be a fraction of the money we spend searching for extraterrestrial life."
'Second genesis'
Professor Davies was one of the speakers at a symposium exploring the possibility that life has evolved on Earth more than once.
The descendants of this "second genesis" may have survived until today in a "shadow biosphere" which is beyond our radar because its inhabitants have biochemistry so different from our own.
"All our microscopes are customised for life as we know it - so it's no surprise that we haven't found microbes with different biochemistry," said Professor Davies.
"We don't quite know how weird life would look. It's as wide as the imagination and that's why it's really hard to look for."
If it exists, weird life could be based on DNA and RNA - but with a slightly different genetic code or different amino acids.
At the other end of the spectrum, we could find creatures which have more drastic differences.
"Maybe one of the elements life uses - carbon, hydrogen, oxygen, nitrogen, phosphorus - could be replaced by something else," said Professor Davies.
"When I say that, everyone immediately thinks of silicon life - because of Star Trek. But I'm not talking about anything that drastic.
"For example, most of the jobs that can be done by phosphorus can be done by arsenic."
Arsenic may be poisonous to humans, but it has chemical properties which might make it ideal in a microbe's machinery, he said.
'Mission to Earth'
So how do we go about hunting for something we have never seen before?
"There are two possibilities," said Prof Davies, Director of the BEYOND Center for Fundamental Concepts in Science.
"One is that weird life is ecologically isolated, in niches beyond the reach of mankind."
In this case, we must begin trawling the world's most inhospitable environments - deserts, salt lakes, and areas of high pressure, temperature or UV radiation.
"We could have a 'mission to Earth'. There's a big long list of places we could be looking," observed Professor Davies.
"For example, if we are looking for arsenic life, we could head for environments which are both arsenic rich and phosphorus poor - such as deep ocean vents.
"There is also a heavily contaminated lake in California which is arsenic rich - Mono Lake - and we do find microbes in there which get their energy from arsenic.
"But they don't actually incorporate the arsenic into themselves. They spit it back out again. They smoke but they don't inhale."
On the other hand, it could be that "weird life" is actually all around us - intermingled with carbon based life.
"In that case it's going to be really hard to detect - you have to find some way of filtering everything else out."
This laborious process has been used to search for unknown organisms in seawater - by painstakingly filtering everything else away.
If we did discover something unprecedented, "we'd all start arguing" said Professor Davies, a theoretical physicist.
"The question would be whether this life was truly different, or whether there was a common precursor a deep branch on the main tree of life.
"Also, how do we know we are dealing with separate Earth genesis and not a Mars genesis?
"We know rocks do get traded between the two planets, and life could hitch a ride.
"Personally, I'm only interested in establishing whether life happened more than once. If we find it has happened twice from scratch then its going to have happened all around the universe.
"It's going to be teeming with life and there's a very good chance we are not alone."
Life in the lab
Another way to determine what alternative life might look like is to try to invent it ourselves.
If we can create new molecules which can behave in life-like way, we may then go out and look for these in the environment, says Professor Steven Benner, of the University of Florida.
His team have created perhaps the closest yet to a man-made alternative form of life.
"We are announcing the first example of an artificial synthetic chemical system capable of Darwinian evolution," he told the conference.
"Is it alive? Well, I can tell you that it is not self-sustaining.
"You have to have a graduate student stand there and feed it from time to time, but it is evolving."
The molecule is essentially a modified version of our own DNA double helix - but with six "letters" in its genetic alphabet, instead of four.
These nucleotides pair up in strands, which can replicate, though only with the help of polymerase enzymes and heat.
"Sometimes mistakes are made in pairing and these mistakes are maintained in the next generation - it is evolving," said Prof Brenner.
"The next step is to apply natural selection to it, to see if it can evolve under selective pressure.
"The accepted definition of life is a molecule capable of Darwinian evolution, so we are trying to put together molecules that are capable of doing it."
But he questioned whether our definition of "living" is perhaps too "Earth-centric".
"Remember - just because you are a chemical system which is self-sustaining and capable of Darwinian evolution, that doesn't mean that is the universal definition of life," he said.
http://news.bbc.co.uk/1/hi/sci/tech/7893414.stm
Genetic differences between yeasts greater than those between humans and chimpanzees
The mapping of the entire yeast genome in 1996 marked the beginning of a revolution in biological and medical research. The human genome was mapped in 2001, and by now the number of characterised species is approaching 1000, most of which are bacteria. The next advance is only a few years away – mapping the genetic evolution of individual multicellular animals, including humans."We shall then be able to identify the genetic causes of human disease and to understand how the process of evolution works when species are being formed," says Anders Blomberg, professor at the Department of Cell and Molecular Biology, University of Gothenburg.
Anders Blomberg and his colleague Jonas Warringer are publishing a paper in the highly respected scientific journal Nature, that to some extent leads to a new era in evolutionary and functional genetics research. The lowly yeast is, once again, leading the way.
In collaboration with the Sanger Institute in Cambridge, and the University of Nottingham, the Gothenburg researchers have succeeded in sequencing the DNA and characterising the genome properties (i.e. phenotypes) of 70 different individual organisms from two different species of yeast – the common brewer's yeast Saccharomyces cerevisiae and its evolutionary cousin Saccharomyces paradoxus. The paper presents several interesting conclusions, e.g. that human alcohol consumption has altered yeast DNA.
"As humans transported wine and beer yeasts around the world, different yeasts have mated and recombined, so that the strains of today carry gene variants from various parts of the world. This mosaic pattern is not at all visible in our studies of another yeast that has not been exploited by humans," says Anders Blomberg.
The study also shows that there can be greater genetic differences between individuals within a particular species of yeast than there are between humans and chimpanzees. The DNA of individual yeast organisms can vary by up to 4 per cent, compared to the 1 per cent difference between the DNA of humans and chimpanzees. Another interesting observation is that individual organisms from the same species can have extra genetic material. Most of these "extra genes" occur at the periphery of the chromosome (the telomer region), which lends support to the theory that these areas are very important in evolution.
http://www.eurekalert.org/pub_releases/2009-02/uog-gdb021309.php
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