2 December 2010 Last updated at 12:23 ET

Arsenic-loving bacteria may help in hunt for alien life

By Jason Palmer Science and technology reporter, BBC News


Halomonadaceae bacteria The bacteria slowly incorporated arsenic into their innermost workings


The first organism able to substitute one of the six chemical elements crucial to life has been found.

The bacterium, found in a California lake, uses the usually poisonous element arsenic in place of phosphorus.

The find, described in Science, gives weight to the long-standing idea that life on other planets may have a radically different chemical makeup.

It also has implications for the way life arose on Earth - and how many times it may have done so.

The "extremophile" bacteria were found in a briny lake in eastern California in the US.

While bacteria have been found in inhospitable environments and can consume what other life finds poisonous, this bacterial strain has actually taken arsenic on board in its cellular machinery.

Until now, the idea has been that life on Earth must be composed of at least the six elements carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus - no example had ever been found that violates this golden rule of biochemistry.

The bacteria were found as part of a hunt for life forms radically different from those we know.

"At the moment we have no idea if life is just a freak, bizarre accident which is confined to Earth or whether it is a natural part of a fundamentally biofriendly universe in which life pops up wherever there are Earth-like conditions," explained Paul Davies, the Arizona State University and Nasa Astrobiology Institute researcher who co-authored the research.

"Although it is fashionable to support the latter view, we have zero evidence in favour of it," he told BBC News.

"If that is the case then life should've started many times on Earth - so perhaps there's a 'shadow biosphere' all around us and we've overlooked it because it doesn't look terribly remarkable."
As unexpected

Proof of that idea could come in the form of organisms on Earth that break the "golden rules" of biochemistry - in effect, finding life that evolved separately from our own lineage.
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“Start Quote

The take-home message is: who knows what else is there? We've only scratched the surface of the microbial realm”

End Quote Professor Paul Davies Arizona State University

Study lead author Felisa Wolfe-Simon and her colleagues Professor Davies and Ariel Anbar of Arizona State University initially suggested in a paper an alternative scheme to life as we know it.

Their idea was that there might be life in which the normally poisonous element arsenic (in particular as chemical groups known as arsenates) could work in place of phosphorus and phosphates.

Putting it to the test, the three authors teamed up with a number of collaborators and began to study the bacteria that live in Mono Lake in California, home to arsenic-rich waters.

The researchers began to grow the bacteria in a laboratory on a diet of increasing levels of arsenic, finding to their surprise that the microbes eventually fully took up the element, even incorporating it into the phosphate groups that cling to the bacteria's DNA.

Notably, the research found that the bacteria thrived best in a phosphorus environment.

That probably means that the bacteria, while a striking first for science, are not a sign of a "second genesis" of life on Earth, adapted specifically to work best with arsenic in place of phosphorus.
'Weird branch'

However, Professor Davies said, the fact that an organism that breaks such a perceived cardinal rule of life makes it is a promising step forward.

"This is just a weird branch on the known tree of life," said Professor Davies. "We're interested ultimately in finding a different tree of life... that will be the thing that will have massive implications in the search for life in the Universe.

"The take-home message is: who knows what else is there? We've only scratched the surface of the microbial realm."

John Elliott, a Leeds Metropolitan University researcher who is a veteran of the UK's search for extraterestrial life, called the find a "major discovery".
Mono Lake, California (H Bortman) The bacteria were found in the salty Mono Lake

"It starts to show life can survive outside the traditional truths and universals that we thought you have to use... this is knocking one brick out of that wall," he said.

"The general consensus is that this really could still be an evolutionary adapatation rather than a second genesis. But it's early days, within about the first year of this project; it's certainly one to think on and keep looking for that second genesis, because you've almost immediately found an example of something that's new."

Simon Conway Morris of the University of Cambridge agreed that, whatever its implications for extraterrestrial life, the find was significant for what we understand about life on Earth.

"The bacteria is effectively painted by the investigators into an 'arsenic corner', so what it certainly shows is the astonishing and perhaps under-appreciated versatility of life," he told BBC News.

"It opens some really exciting prospects as to both un-appreciated metabolic versatility... and prompting the questions as to the possible element inventory of remote Earth-like planets".

8 February 2011 Last updated at 07:19 ET


Studying how snakes got legless

By Jonathan Amos Science correspondent, BBC News

Fossil snake (Alexandra Houssaye) The snake would have slithered along the ground during the Late Cretaceous


A 95-million-year-old fossil is helping scientists understand how snakes lost their legs through evolutionary time.

Found in Lebanon, the specimen is one of only three examples of an ancient snake with preserved leg bones.

One rear leg is clearly visible but researchers had to use a novel X-ray technique to examine another leg hidden inside the fossil rock.

Writing in the Journal of Vertebrate Paleontology, the team says the snake records an early stage in limb loss.

The scientists' high-resolution 3D images suggest the legs in this particular species, Eupodophis descouensi, grew more slowly, or for a shorter period of time.

It is a conclusion made possible only after seeing all the bones obscured inside the limestone, and determining that although the creature possessed ankle bones, it actually had neither foot nor toe bones.

"This study reveals the degree of regression of the legs," said Dr Alexandra Houssaye from the Museum National d'Histoire Naturelle (MNHN) in Paris, France.


X-ray of bones (ESRF) Revealed: Scientists see features on the scale of a few micrometers

"This could not be clearly determined based only on the visible leg, as some tiny bones such as ankle and foot bones might have been broken or removed from the surface. However, as all the second leg was preserved in the rock, we can now be almost completely sure of the degree of resorption of the leg," she told BBC News.

Current evidence suggests that snakes started to evolve less than 150 million years ago.

Two theories compete. One points to a land origin in which lizards started to burrow, and as they adapted to their subterranean existence, their legs were reduced and lost - first the fore-limbs and then the hind-limbs.

The second theory considers the origin to be in water, from marine reptiles.

This makes the few known bipedal snakes in the fossil record hugely significant, because they could hold the clues that settle this particular debate.

But Dr Houssaye says Eupodophis descouensi of itself cannot resolve such arguments.

"This study does not enable us to choose between the two hypotheses," she told BBC News. "In fact, a true answer might not be brought before 10 years.

"That is why our role now is to try to get as much information as possible from the few important fossil remains we have. Hind-limbed snakes are key fossils in this debate and that is why we really need to study them in detail."


Alexandra Houssaye explains how a fossil snake had two legs

The BBC was with Dr Houssaye in 2008 when she took the fossil to the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.

The machine produces a brilliant X-ray beam that can pierce just about any material, revealing its inner structure in incredibly fine detail.

For this study, the fossil snake was clamped to an inclined table and rotated in front of the X-ray beam.

In a process known as computed laminography, many hundreds of 2D images were produced which were then woven, with the aid of a smart algorithm, into a detailed 3D picture. The scientists can see features on the scale of a few micrometers.


Finger pointing to the leg attached to the pelvis of the ancient snake (C. Argoud/ESRF) A finger points to the visible leg of the ancient snake

Eupodophis descouensi was just under a metre long. It would have slithered along the ground during the Late Cretaceous, when dinosaurs still roamed the Earth.

It is unlikely the animal would have used the legs for moving, although it is possible they could have served some other function.

In a number of modern snakes, such as boas and pythons, tiny "spurs" are evident near their rear ends that are used as grippers during sex.

The Eupodophis descouensi fossil was unearthed near the Lebanese village of al-Nammoura and was first described in 2000.

Its remains are divided across the two interior faces of a thin limestone block that has been broken apart.

A portion of the vertebral column is missing; and in the process of preservation, the rear end - with the legs - became detached and positioned near the head.

"It will be interesting to make comparisons now with other fossil specimens but also with [living] lizards and snakes with regressed pelvic and limb elements," Dr Houssaye said.

Ecuadorean Villagers May Hold Secret to Longevity

By NICHOLAS WADE
Published: February 16, 2011


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People living in remote villages in Ecuador have a mutation that some biologists say may throw light on human longevity and ways to increase it.

Enlarge This Image
Arlan Rosenbloom

A 67-year-old man who has Laron-type dwarfism with his daughter, 5, and sons, 7 and 10.
Multimedia


A 32-year-old community leader and artist who has the rare dwarfism condition, with his bride, 17.

The villagers are very small, generally less than three and a half feet tall, and have a rare condition known as Laron syndrome or Laron-type dwarfism. They are probably the descendants of conversos, Sephardic Jews from Spain and Portugal who were forced to convert to Christianity in the 1490s but were nonetheless persecuted in the Inquisition. They are also almost completely free of two age-related diseases, cancer and diabetes.

A group of 99 villagers with Laron syndrome has been studied for 24 years by Dr. Jaime Guevara-Aguirre, an Ecuadorean physician and diabetes specialist. He discovered them when traveling on horseback to a roadless mountain village. Most such villages are inhabited by Indians, but these were Europeans, with Spanish surnames typical of conversos.

As Dr. Guevara-Aguirre accumulated health data on his patients, he noticed a remarkable pattern: though cancer was frequent among people who did not have the Laron mutation, those who did have it almost never got cancer. And they never developed diabetes, even though many were obese, which often brings on the condition.

“I discovered the population in 1987,” Dr. Guevara-Aguirre said in an interview from Ecuador. “In 1994, I noticed these patients were not having cancer, compared with their relatives. People told me they are too few people to make any assumption. People said, ‘You have to wait 10 years,’ so I waited. No one believed me until I got to Valter Longo in 2005.”

Valter D. Longo, a researcher on aging at the University of Southern California, saw the patients as providing an opportunity to explore in people the genetic mutations that researchers had found could make laboratory animals live much longer than usual.

The Laron patients have a mutation in the gene that makes the receptor for growth hormone. The receptor is a protein embedded in the membrane of cells. Its outside region is recognized by growth hormone circulating through the body; the inside region sends signals through the cell when growth hormone triggers the receptor.

The Laron patients’ mutation means that their growth hormone receptor lacks the last eight units of its exterior region, so it cannot react to growth hormone. In normal children, growth hormone makes the cells of the liver churn out another hormone, called insulinlike growth factor, or IGF-1, and this hormone makes the children grow. If the Laron patients are given doses of IGF-1 before puberty, they can grow to fairly normal height.

This is where the physiology of the Laron patients links up with the longevity studies that researchers have been pursuing with laboratory animals. IGF-1 is part of an ancient signaling pathway that exists in the laboratory roundworm as well as in people. The gene that makes the receptor for IGF-1 in the roundworm is called DAF-2. And worms in which this gene is knocked out live twice as long as normal.

The Laron patients have the equivalent defect — their cells make very little IGF-1, so very little IGF-1 signaling takes place, just as in the DAF-2-ablated worms. So the Laron patients might be expected to live much longer.

Because of their striking freedom from cancer and diabetes, they probably could live much longer if they did not have a much higher than usual death rate from causes unrelated to age, like alcoholism and accidents.

Dr. Longo said he believed that having very low levels of IGF-1 was the critical feature of the Laron patients’ freedom from age-related diseases. In collaboration with Dr. Guevara-Aguirre, he exposed human cells growing in a laboratory dish to serum from the Laron patients. The cells were then damaged with a chemical that disrupts their DNA. The Laron serum had two significant effects, the two physicians reported on Wednesday in Science Translational Medicine.

First, the serum protected the cells from genetic damage. Second, it spurred the cells that were damaged to destroy themselves, a mechanism the body uses to prevent damaged cells from becoming cancerous. Both these effects were reversed when small amounts of IGF-1 were added to the serum.

Dr. Longo said that some level of IGF-1 was necessary to protect against heart disease, but that lowering the level might be beneficial. A drug that does this is already on the market for treatment of acromegaly, a thickening of the bones caused by excessive growth hormone. “Our underlying hypothesis is that this drug would prolong life span,” Dr. Longo said. He said he was not taking the drug, called pegvisomant or Somavert, which is very hard to obtain.

A strain of mice bred by John Kopchick of Ohio University has a defect in the growth hormone receptor gene, just as do the Laron patients, and lives 40 percent longer than usual.

Dr. Longo said that his report had first been submitted to Science, a better-known journal, which turned down the paper because of an adverse report from one reviewer.

Andrzej Bartke, a gerontology expert at Southern Illinois University, said that the new result was “very important” and that the authors had done a fine job in following the patients and generating high-quality data. “This fits in with what we are learning from studies in animals about the relationship of growth hormone to aging, because both cancer and diabetes are related to aging,” Dr. Bartke said.

The longest-lived mouse on record is one studied by Dr. Bartke. It had a defect in its growth hormone receptor gene, just as do the Laron patients. “It missed its fifth birthday by a week,” he said. The mouse lived twice as long as usual and won Dr. Bartke a prize presented by the Methuselah Foundation (which rewards developments in life-extension therapies) in 2003.

Dr. Guevara-Aguirre said he had been struggling to get sufficient IGF-1 to treat 30 of his patients before they reached puberty, at which point it will be too late. He said his group of Laron patients, the largest in the world, had provided essential data for drug companies making IGF-1, and he chided the companies for not reciprocating by providing the drug for his patients.

Dr. Arlan Rosenbloom, a pediatric endocrinologist at the University of Florida who has worked with Dr. Guevara-Aguirre, took a similar position. “Considering that the drug companies needed the initial studies to determine dosage and efficacy, it seems ironic that we should have so much difficulty getting the drug,” he said.

Ownership of the drug has passed through several companies’ hands, so any initial obligation may have been weakened. Dr. Guevara-Aguirre also said he believed that the government of Ecuador should do more to help get the drug for his patients.

Dr. Harry Ostrer, a geneticist at New York University who is exploring the Laron patients’ degree of Sephardic ancestry, said that he had seen several of Dr. Guevara-Aguirre’s patients in Quito, Ecuador’s capital, and that they were “remarkably youthful in appearance.”

Shedding our penis spines helped us become human, DNA study hints

Genetic comparison with chimps suggests that losing chunks of DNA – including one associated with penis spines and facial whiskers – played a crucial role in making us human



* Ian Sample, science correspondent
* guardian.co.uk, Wednesday 9 March 2011 18.00 GMT
*

Chimpanzees waiting to be fed The secret of human brain power and social structures may owe more to lost DNA than anything else. Photograph: Gert Janssen/EPA

Scientists have identified a clutch of subtle genetic changes that have shaped our minds and bodies into the unique form that sets humans apart from chimpanzees and the rest of the animal kingdom.

The work by researchers in the US represents a landmark in a search that has occupied philosophers and scientists for millennia and one that goes to the heart of understanding what it means to be human.

The findings offer up the humbling conclusion that the secret of human success may owe more to what we lost along the path of evolution, rather than anything we gained.

When the human genome was first deciphered more than a decade ago, some scientists expected to find extra genes that explained why humans had an intellectual edge over their closest living relatives and other species. But since diverging from chimpanzees around seven million years ago, it turns out that our human ancestors lost several hundred snippets of DNA, which together led to traits that are uniquely human, the researchers claim.

In ditching these chunks of DNA, our ancient ancestors lost facial whiskers and short, tactile spines on their penises. The latter development is thought to have paved the way for more intimate sex and monogamous relationships. The loss of other DNA may have been crucial in allowing humans to grow larger brains.

Intriguingly, hardly any of the lost DNA was from genes, which make the proteins that are the building blocks of life. Instead, the missing DNA came from areas of the genome that regulate where and when certain genes are active.

"Like someone looking for their keys under a lamp post, the genes were the easiest place to look for differences between humans and chimpanzees, and in many respects those have been studied pretty well," said Philip Reno, a co-author on the study at Penn State University.

"But there is a larger unknown in the form of these other regions of DNA, and in those we are only just beginning to find ways to pull out the differences between humans and chimpanzees."

In the years since the human genome project was completed it has become clear that humans and chimps share around 96% of their DNA. Of the three billion pairs of "letters" that make up the human genetic code, genes account for less than 2%.

The US team compared the complete human genome with sequences from the chimp, macaque and mouse. They found that humans lack 510 short sections of DNA that are present in the other animals. Intriguingly, only one missing piece of DNA affected a human gene directly. The vast majority of lost DNA disrupted parts of the genome that control how genes are expressed.

One missing section of DNA was found to block a gene that, in other animals, stifles the growth of brain cells. Losing that DNA may have been a pivotal moment in human development, as it allowed parts of the human brain to expand into the most complex organ known.

Writing in the journal Nature, the researchers describe how our ancestors lost another piece of DNA that gives rise to both facial whiskers and sensitive spines on the tip of the penis, both of which are found in chimpanzees and other non-human primates.

Penile spines – which make the penis more sensitive and speed ejaculation – are more common in animals that face intense competition for mates, and where females are likely to mate with many males in rapid succession.

The loss of penile spines may have allowed our ancient ancestors to copulate for longer, a development thought to have nurtured monogamous couples and paved the way for more complex social structures.

When the scientists checked their genetic discoveries against the Neanderthal genome, they found the same chunks of DNA were missing, meaning the DNA was lost more than 800,000 years ago, which is when our human ancestors split from the Neanderthal lineage.

The scientists are still working out what many of the lost sections of DNA do, but expect to find more evidence of how humans differ genetically from chimpanzees.

"There are going to be many different features that make humans unique and I don't think we're close to describing all the links between genes that make us different from chimpanzees," said Reno. "We are just getting the initial picture."

Shedding our penis spines helped us become human, DNA study hints

Genetic comparison with chimps suggests that losing chunks of DNA – including one associated with penis spines and facial whiskers – played a crucial role in making us human
.
In ditching these chunks of DNA, our ancient ancestors lost facial whiskers and short, tactile spines on their penises. The latter development is thought to have paved the way for more intimate sex and monogamous relationships. The loss of other DNA may have been crucial in allowing humans to grow larger brains.

Writing in the journal Nature, the researchers describe how our ancestors lost another piece of DNA that gives rise to both facial whiskers and sensitive spines on the tip of the penis, both of which are found in chimpanzees and other non-human primates.

Penile spines – which make the penis more sensitive and speed ejaculation – are more common in animals that face intense competition for mates, and where females are likely to mate with many males in rapid succession.

The loss of penile spines may have allowed our ancient ancestors to copulate for longer, a development thought to have nurtured monogamous couples and paved the way for more complex social structures.



This just in:
Archaelogists and a group of scientists have just reported finding a human tribe in a remote section of the Jungles of Ecuador, where the men have "cat like whiskers and spined penises". Further studies observed that the women of this tribe seemed bitchy, frigid and and noticably elusive!!
(I know this is a serious conversation, but I couldn't resist!)

whoops!!~! edited.

The BEST comment you have ever written.....PLEASE stick to writing that and ONLY that.