Thursday, June 9, 2011
Friday, August 13, 2010
Tenure and Turing Award
Ken Iverson was denied tenure at Harvard in 1959,went to IBM Research, and won the Turing award in 1979. http://keiapl.info/anec/#one_little_bookEdsger Dijkstra was denied tenure at Amsterdam in 1970,went to UT Austin, and won the Turing award in 1972.http://www.cbi.umn.edu/oh/pdf.phtml?id=317 page 12Stephen Cook was denied tenure at UC Berkeley in 1970,went to the University of Toronto, and won the Turing award in 1983.http://www.cbi.umn.edu/oh/pdf.phtml?id=317 page 12
Wednesday, July 22, 2009
Strange! Humans Glow in Visible Light - Yahoo! News
Strange! Humans Glow in Visible Light - Yahoo! News
The human body literally glows, emitting a visible light in extremely small quantities at levels that rise and fall with the day, scientists now reveal.
Past research has shown that the body emits visible light, 1,000 times less intense than the levels to which our naked eyes are sensitive. In fact, virtually all living creatures emit very weak light, which is thought to be a byproduct of biochemical reactions involving free radicals.
(This visible light differs from the infrared radiation - an invisible form of light - that comes from body heat.)
To learn more about this faint visible light, scientists in Japan employed extraordinarily sensitive cameras capable of detecting single photons. Five healthy male volunteers in their 20s were placed bare-chested in front of the cameras in complete darkness in light-tight rooms for 20 minutes every three hours from 10 a.m. to 10 p.m. for three days.
The researchers found the body glow rose and fell over the day, with its lowest point at 10 a.m. and its peak at 4 p.m., dropping gradually after that. These findings suggest there is light emission linked to our body clocks, most likely due to how our metabolic rhythms fluctuate over the course of the day.
Faces glowed more than the rest of the body. This might be because faces are more tanned than the rest of the body, since they get more exposure to sunlight - the pigment behind skin color, melanin, has fluorescent components that could enhance the body's miniscule light production.
Since this faint light is linked with the body's metabolism, this finding suggests cameras that can spot the weak emissions could help spot medical conditions, said researcher Hitoshi Okamura, a circadian biologist at Kyoto University in Japan.
"If you can see the glimmer from the body's surface, you could see the whole body condition," said researcher Masaki Kobayashi, a biomedical photonics specialist at the Tohoku Institute of Technology in Sendai, Japan.
The scientists detailed their findings online July 16 in the journal PLoS ONE.
The human body literally glows, emitting a visible light in extremely small quantities at levels that rise and fall with the day, scientists now reveal.
Past research has shown that the body emits visible light, 1,000 times less intense than the levels to which our naked eyes are sensitive. In fact, virtually all living creatures emit very weak light, which is thought to be a byproduct of biochemical reactions involving free radicals.
(This visible light differs from the infrared radiation - an invisible form of light - that comes from body heat.)
To learn more about this faint visible light, scientists in Japan employed extraordinarily sensitive cameras capable of detecting single photons. Five healthy male volunteers in their 20s were placed bare-chested in front of the cameras in complete darkness in light-tight rooms for 20 minutes every three hours from 10 a.m. to 10 p.m. for three days.
The researchers found the body glow rose and fell over the day, with its lowest point at 10 a.m. and its peak at 4 p.m., dropping gradually after that. These findings suggest there is light emission linked to our body clocks, most likely due to how our metabolic rhythms fluctuate over the course of the day.
Faces glowed more than the rest of the body. This might be because faces are more tanned than the rest of the body, since they get more exposure to sunlight - the pigment behind skin color, melanin, has fluorescent components that could enhance the body's miniscule light production.
Since this faint light is linked with the body's metabolism, this finding suggests cameras that can spot the weak emissions could help spot medical conditions, said researcher Hitoshi Okamura, a circadian biologist at Kyoto University in Japan.
"If you can see the glimmer from the body's surface, you could see the whole body condition," said researcher Masaki Kobayashi, a biomedical photonics specialist at the Tohoku Institute of Technology in Sendai, Japan.
The scientists detailed their findings online July 16 in the journal PLoS ONE.
Tuesday, February 24, 2009
Music-Memory Connection Found in Brain | LiveScience
Music-Memory Connection Found in Brain LiveScience
People have long known that music can trigger powerful recollections, but now a brain-scan study has revealed where this happens in our noggins.
The part of the brain known as the medial pre-frontal cortex sits just behind the forehead, acting like recent Oscar host Hugh Jackman singing and dancing down Hollywood's memory lane.
"What seems to happen is that a piece of familiar music serves as a soundtrack for a mental movie that starts playing in our head." said Petr Janata, a cognitive neuroscientist at University of California, Davis. "It calls back memories of a particular person or place, and you might all of a sudden see that person's face in your mind's eye."
Janata began suspecting the medial pre-frontal cortex as a music-processing and music-memories region when he saw that part of the brain actively tracking chord and key changes in music. He had also seen studies which showed the same region lighting up in response to self-reflection and recall of autobiographical details, and so he decided to examine the possible music-memory link by recruiting 13 UC-Davis students.
Test subjects went under an fMRI brain scanner and listened to 30 different songs randomly chosen from the Billboard "Top 100" music charts from years when the subjects would have been 8 to 18 years old. They signaled researchers when a certain 30-second music sample triggered any autobiographical memory, as opposed to just being a familiar or unfamiliar song.
"This is the first study using music to evoke autobiographical memory," Janata told LiveScience. His full study is detailed online this week in the journal Cerebral Cortex.
The students also filled out the details of their memories in a survey immediately following the MRI session, explaining the content and clarity of their recollections. Most recognized about 17 out of 30 music samples on average, with about 13 having moderate or strong links with a memory from their lives.
Janata saw that tunes linked to the strongest self-reported memories triggered the most vivid and emotion-filled responses – findings corroborated by the brain scan showing spikes in mental activity within the medial prefrontal cortex.
The brain region responded quickly to music signature and timescale, but also reacted overall when a tune was autobiographically relevant. Furthermore, music tracking activity in the brain was stronger during more powerful autobiographical memories.
This latest research could explain why even Alzheimer's patients who endure increasing memory loss can still recall songs from their distant past.
"What's striking is that the prefrontal cortex is among the last [brain regions] to atrophy," Janata noted. He pointed to behavioral observations of Alzheimer's patients singing along or brightening up when familiar songs came on.
Janata said that his research merely tried to establish a neuroscience basis for why music can tickle memory. He voiced the hope that his and other studies could encourage practices such as giving iPods to Alzheimer's patients – perhaps providing real-life testament to the power of music.
"It's not going to reverse the disease," Janata said. "But if you can make quality of life better, why not?"
People have long known that music can trigger powerful recollections, but now a brain-scan study has revealed where this happens in our noggins.
The part of the brain known as the medial pre-frontal cortex sits just behind the forehead, acting like recent Oscar host Hugh Jackman singing and dancing down Hollywood's memory lane.
"What seems to happen is that a piece of familiar music serves as a soundtrack for a mental movie that starts playing in our head." said Petr Janata, a cognitive neuroscientist at University of California, Davis. "It calls back memories of a particular person or place, and you might all of a sudden see that person's face in your mind's eye."
Janata began suspecting the medial pre-frontal cortex as a music-processing and music-memories region when he saw that part of the brain actively tracking chord and key changes in music. He had also seen studies which showed the same region lighting up in response to self-reflection and recall of autobiographical details, and so he decided to examine the possible music-memory link by recruiting 13 UC-Davis students.
Test subjects went under an fMRI brain scanner and listened to 30 different songs randomly chosen from the Billboard "Top 100" music charts from years when the subjects would have been 8 to 18 years old. They signaled researchers when a certain 30-second music sample triggered any autobiographical memory, as opposed to just being a familiar or unfamiliar song.
"This is the first study using music to evoke autobiographical memory," Janata told LiveScience. His full study is detailed online this week in the journal Cerebral Cortex.
The students also filled out the details of their memories in a survey immediately following the MRI session, explaining the content and clarity of their recollections. Most recognized about 17 out of 30 music samples on average, with about 13 having moderate or strong links with a memory from their lives.
Janata saw that tunes linked to the strongest self-reported memories triggered the most vivid and emotion-filled responses – findings corroborated by the brain scan showing spikes in mental activity within the medial prefrontal cortex.
The brain region responded quickly to music signature and timescale, but also reacted overall when a tune was autobiographically relevant. Furthermore, music tracking activity in the brain was stronger during more powerful autobiographical memories.
This latest research could explain why even Alzheimer's patients who endure increasing memory loss can still recall songs from their distant past.
"What's striking is that the prefrontal cortex is among the last [brain regions] to atrophy," Janata noted. He pointed to behavioral observations of Alzheimer's patients singing along or brightening up when familiar songs came on.
Janata said that his research merely tried to establish a neuroscience basis for why music can tickle memory. He voiced the hope that his and other studies could encourage practices such as giving iPods to Alzheimer's patients – perhaps providing real-life testament to the power of music.
"It's not going to reverse the disease," Janata said. "But if you can make quality of life better, why not?"
Wednesday, February 18, 2009
Forensic Science System Needs Overhaul | LiveScience
Forensic Science System Needs Overhaul LiveScience
On CSI, forensic science nearly always leads to a closed case. Reality is far different. And the system needs vast change, a new report claims.
With the exception of nuclear DNA analysis, says the report from the National Research Council, "no forensic method has been rigorously shown able to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source."
That means fingerprinting techniques and lie detection methods, among others, can lead to convictions of innocent people and, of course, fail to help convict bad guys. The report writers were careful not to pass judgment on any specific past cases, however. Rather, they looked at the overall state of things.
Other studies have shown the weaknesses of some common methods used in courtrooms:
In 2002, a study by the National Academy of Sciences revealed that "polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection."
A study in 2005 found that though people often claim to recognize a suspect they had spotted from hundreds of feet away, a person with 20/20 vision can't recognize a celebrity's face at 110 feet.
A study in the Journal of Criminal Law & Criminology indicated that there are hundreds of errors made each year in fingerprint matching.
The new, congressionally mandated report "finds serious deficiencies in the nation's forensic science system and calls for major reforms and new research," according to a statement released today by the National Academy of Sciences.
Rigorous and mandatory certification programs for forensic scientists are lacking, the report says, as are strong standards and protocols for analyzing and reporting on evidence.
Non-DNA forensic disciplines have important roles, the report states, but many need substantial research to validate basic premises and techniques, assess limitations, and discern the sources and magnitude of error. "There is a dearth of peer-reviewed, published studies establishing the scientific bases and reliability of many forensic methods," the committee writes. "Moreover, many forensic science labs are underfunded, understaffed, and have no effective oversight."
Meanwhile, laws governing how crime is prosecuted vary greatly by state. Recently, Washington state proposed to collect DNA samples from suspects in cases as minor as shoplifting. Yet in Los Angeles, the police department recently was found to have in cold storage nearly 7,000 untested DNA samples from sexual assault cases. Last year the department let the deadline pass for prosecuting some 200 potential sexual assault cases without ever testing DNA evidence on file that might have resulted in convictions.
"Reliable forensic evidence increases the ability of law enforcement officials to identify those who commit crimes, and it protects innocent people from being convicted of crimes they didn't commit," said committee co-chair Harry T. Edwards, senior circuit judge and chief judge emeritus of the U.S. Court of Appeals for the District of Columbia Circuit. "Because it is clear that judicial review alone will not cure the infirmities of the forensic science community, there is a tremendous need for the forensic science community to improve."
Edwards and his colleagues today urged Congress to establish a new, independent National Institute of Forensic Science to lead research efforts, set and enforce standards for forensic science professionals and laboratories, and oversee education standards.
On CSI, forensic science nearly always leads to a closed case. Reality is far different. And the system needs vast change, a new report claims.
With the exception of nuclear DNA analysis, says the report from the National Research Council, "no forensic method has been rigorously shown able to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source."
That means fingerprinting techniques and lie detection methods, among others, can lead to convictions of innocent people and, of course, fail to help convict bad guys. The report writers were careful not to pass judgment on any specific past cases, however. Rather, they looked at the overall state of things.
Other studies have shown the weaknesses of some common methods used in courtrooms:
In 2002, a study by the National Academy of Sciences revealed that "polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection."
A study in 2005 found that though people often claim to recognize a suspect they had spotted from hundreds of feet away, a person with 20/20 vision can't recognize a celebrity's face at 110 feet.
A study in the Journal of Criminal Law & Criminology indicated that there are hundreds of errors made each year in fingerprint matching.
The new, congressionally mandated report "finds serious deficiencies in the nation's forensic science system and calls for major reforms and new research," according to a statement released today by the National Academy of Sciences.
Rigorous and mandatory certification programs for forensic scientists are lacking, the report says, as are strong standards and protocols for analyzing and reporting on evidence.
Non-DNA forensic disciplines have important roles, the report states, but many need substantial research to validate basic premises and techniques, assess limitations, and discern the sources and magnitude of error. "There is a dearth of peer-reviewed, published studies establishing the scientific bases and reliability of many forensic methods," the committee writes. "Moreover, many forensic science labs are underfunded, understaffed, and have no effective oversight."
Meanwhile, laws governing how crime is prosecuted vary greatly by state. Recently, Washington state proposed to collect DNA samples from suspects in cases as minor as shoplifting. Yet in Los Angeles, the police department recently was found to have in cold storage nearly 7,000 untested DNA samples from sexual assault cases. Last year the department let the deadline pass for prosecuting some 200 potential sexual assault cases without ever testing DNA evidence on file that might have resulted in convictions.
"Reliable forensic evidence increases the ability of law enforcement officials to identify those who commit crimes, and it protects innocent people from being convicted of crimes they didn't commit," said committee co-chair Harry T. Edwards, senior circuit judge and chief judge emeritus of the U.S. Court of Appeals for the District of Columbia Circuit. "Because it is clear that judicial review alone will not cure the infirmities of the forensic science community, there is a tremendous need for the forensic science community to improve."
Edwards and his colleagues today urged Congress to establish a new, independent National Institute of Forensic Science to lead research efforts, set and enforce standards for forensic science professionals and laboratories, and oversee education standards.
Idea of Infinity Stretched Back to Third Century B.C. | LiveScience
Idea of Infinity Stretched Back to Third Century B.C. LiveScience
CHICAGO - The first mathematical use of the concept of actual infinity has been pushed back some 2,000 years via a new analysis of a tattered page of parchment on which a medieval monk in Constantinople copied the third century B.C. work of the Greek mathematician Archimedes.
Infinity is one of the most fundamental questions in mathematics and still remains an unsolved riddle. For instance, if you add or subtract a number from infinity, the remaining value is still infinity, some Indian philosophers said. Mathematicians today refer to actual infinity as an uncountable set of numbers such as the number of points existing on a line at the same time, while a potential infinity is an endless sequence that unfolds consecutively over time.
The parchment page comes from the 348-page Archimedes Palimpsest, the oldest copy of some of the Greek genius' writings, which were hidden for centuries because a monk partly scraped them off the animal-skin parchment in the 13th century A.D. to clear the pages to print a prayer book. Also, a forger painted pictures over the prayer book hundreds of years after that.
A scholar named Johan Ludvig Heiberg in 1906 studied the written remnants behind the religious words to discover the Palimpsest, finding evidence of Archimedes' systematic use of the concept of infinity in a portion of the document called the Method of Mechanical Theorems. In the past few years, the Palimpsest was re-examined at a far higher level of detail using multispectral imaging and also a hair-thin X-ray scanning technique at Stanford University's Synchrotron Radiation Lightsource in California. The scanner can image a million pixels in less than one hour.
With one of the X-ray images, Stanford classicist Reviel Netz made out the edge of a torn page, where Heiberg had figured just one line of text was missing. The X-rays produced images of iron from the ink used on the document.
Netz examined the scan and was able to deduce the presence of previously unseen Greek letters, kappa and alpha, which were likely followed by an iota to spell the Greek word for "and." This led Netz to conclude that two lines were missing, rather than one and to arrive at a new reading of the passage, physicist Uwe Bergmann of the Synchrotron facility told a small group of reporters here Sunday at the American Association for the Advancement of Science.
"Scholars are now talking about some new words which are emerging in the reconstruction of the evidence in introduction to the Method, that Archimedes' concept of infinity was rather different from what was previously thought," Bergmann said.
In fact, the new reading reveals that Archimedes was engaged in math that made conceptual use of actual infinity, as Netz describes on the Web site ArchimedesPalimpsest.org. The calculations involved adding infinite numbers of sums, such as the number of triangles inside a prism, as well as the number of lines inside a rectangle. Archimedes tried to argue that these values are equal to each other, making a statement about actual infinity, not just potential infinity, Nets writes.
The Palimpsest resides at the Walters Museum of Art in Baltimore.
The Archimedes Palimpsest project forced researchers to come up with a new system to scan large objects, Bergmann said. A commercial-grade X-ray scanning machine might take a year to complete a scan that the Stanford Synchrotron now can complete in half a day, he said.
"It is now taking milliseconds rather than seconds to get each pixel — that has been for us the great novelty," he said.
CHICAGO - The first mathematical use of the concept of actual infinity has been pushed back some 2,000 years via a new analysis of a tattered page of parchment on which a medieval monk in Constantinople copied the third century B.C. work of the Greek mathematician Archimedes.
Infinity is one of the most fundamental questions in mathematics and still remains an unsolved riddle. For instance, if you add or subtract a number from infinity, the remaining value is still infinity, some Indian philosophers said. Mathematicians today refer to actual infinity as an uncountable set of numbers such as the number of points existing on a line at the same time, while a potential infinity is an endless sequence that unfolds consecutively over time.
The parchment page comes from the 348-page Archimedes Palimpsest, the oldest copy of some of the Greek genius' writings, which were hidden for centuries because a monk partly scraped them off the animal-skin parchment in the 13th century A.D. to clear the pages to print a prayer book. Also, a forger painted pictures over the prayer book hundreds of years after that.
A scholar named Johan Ludvig Heiberg in 1906 studied the written remnants behind the religious words to discover the Palimpsest, finding evidence of Archimedes' systematic use of the concept of infinity in a portion of the document called the Method of Mechanical Theorems. In the past few years, the Palimpsest was re-examined at a far higher level of detail using multispectral imaging and also a hair-thin X-ray scanning technique at Stanford University's Synchrotron Radiation Lightsource in California. The scanner can image a million pixels in less than one hour.
With one of the X-ray images, Stanford classicist Reviel Netz made out the edge of a torn page, where Heiberg had figured just one line of text was missing. The X-rays produced images of iron from the ink used on the document.
Netz examined the scan and was able to deduce the presence of previously unseen Greek letters, kappa and alpha, which were likely followed by an iota to spell the Greek word for "and." This led Netz to conclude that two lines were missing, rather than one and to arrive at a new reading of the passage, physicist Uwe Bergmann of the Synchrotron facility told a small group of reporters here Sunday at the American Association for the Advancement of Science.
"Scholars are now talking about some new words which are emerging in the reconstruction of the evidence in introduction to the Method, that Archimedes' concept of infinity was rather different from what was previously thought," Bergmann said.
In fact, the new reading reveals that Archimedes was engaged in math that made conceptual use of actual infinity, as Netz describes on the Web site ArchimedesPalimpsest.org. The calculations involved adding infinite numbers of sums, such as the number of triangles inside a prism, as well as the number of lines inside a rectangle. Archimedes tried to argue that these values are equal to each other, making a statement about actual infinity, not just potential infinity, Nets writes.
The Palimpsest resides at the Walters Museum of Art in Baltimore.
The Archimedes Palimpsest project forced researchers to come up with a new system to scan large objects, Bergmann said. A commercial-grade X-ray scanning machine might take a year to complete a scan that the Stanford Synchrotron now can complete in half a day, he said.
"It is now taking milliseconds rather than seconds to get each pixel — that has been for us the great novelty," he said.
Monday, February 16, 2009
New Artificial DNA Points to Alien Life | LiveScience
New Artificial DNA Points to Alien Life LiveScience
CHICAGO — A strange, new genetic code a lot like that found in all terrestrial life is sitting in a beaker full of oily water in a laboratory in Florida, a scientist said today, calling it the first example of an artificial chemical system that is capable of Darwinian evolution.
The system is made of the four molecules that are the basic building blocks of our DNA along with eight synthetic modifications of them, said biochemist Steven A. Benner of the Foundation for Applied Molecular Evolution in Gainesville.
The main difference between the synthetic molecules and those that make up conventional DNA is that Benner's molecules cannot make copies of themselves, although that is just "a couple of years" away, he said.
The wild biochemistry finding, described to a small group of reporters today at the annual meeting of the American Association for the Advancement of Science, offers ideas about new types of life for scientists to look for beyond our planet, or even possibly hidden on our planet.
"Unless it happens to shoot at you with a ray gun, the life that you encounter off of Earth will not necessarily have same biochemistry as us," Benner said.
And the step from Benner's system to something that could be called artificial life is still large. "There is not enough information in them to build organisms," Benner said.
Expanded alphabet for DNA
For some 20 years, Benner's labs have been involved in trying to make artificial life or things approximating it, with similar genetic and inheritance properties to life on Earth. (Previously, Benner worked at the University of Florida.)
He and his colleagues have focused in part on expanding the DNA alphabet to develop an "Artificially Expanded Genetic Information System," which now has its own supporting molecular biology.
The building blocks of DNA are four chemicals called nucleotides that are referred to as A, C, T and G, for short. The nucleotides pair up and bond in predictable ways to form the double helix structure of DNA. Benner's new nucleotides, which he and his colleagues have named Z, P, V, J, Iso-C, Iso-G, X and K, are reshufflings of the constituents of those molecules found in our DNA.
The evolution in this system happens when the 12-letter genetic code makes copying mistakes and subsequent sequences have properties that make them more liable to get copied. Those sequences would survive in greater numbers than the original sequence.
Benner's synthetic approach was conceptualized using "ball and stick plastic model chemistry," he said, the technique used by James Watson and Francis Crick to arrive at the structure of the DNA molecule in 1953.
The human genome's DNA includes 3 billion base pairs. Some of the molecules synthesized in Benner's lab are 81 base pairs long — relatively short.
The molecules are "fed" and grow via a process called the polymerase chain reaction (PCR) that allows the molecules to make copies of themselves. Once the replication of the molecules in Benner's system is self-catalyzed, without PCR, the process is self-sustaining. Benner claims, "then it's artificial life."
Dreaming up extra-terrestrial life
The research resulted from a NASA-funded project to try to understand what life might look like beyond Earth. Such life might live in water, but it could also live in liquid nitrogen or methane (as speculated for Saturn's moon Titan) and in environments with extremely high or low acidity.
The results are published in a technical book, "Life, the Universe and the Scientific Method," of which Benner has made about 100 copies to distribute to his colleagues.
"One of the ways scientists try to understand life as a universal concept ... is you try to make life on your own in the lab," Benner said. "We try to put together chemicals that do that."
Any potential life forms made from such molecules would be "so alien in terms of their biochemistry that they will not able to eat you," Benner said.
NASA has been involved in searching for extra-terrestrial life along numerous avenues for decades, including the Viking mission to Mars in the 1970s and its recent missions to the red planet which have searched for signs of habitability there. NASA also funds an Astrobiology Institute, which partners with hundreds of researchers world-wide who study of the origins, evolution, distribution and future of life in the universe
The trick to searching for alien life is how to look for it, said Paul Davies of Arizona State University, who also spoke with reporters here today.
"All of the techniques which microbiologists use to [look for alien life] are customized to life as we know it," Davies said. "It's no surprise that microbiologists haven't come across micro-organisms that seem to have relatively different biochemistry."
In the future, more scientists could "talk with Steve Benner," Davies said, "to come up with perfectly good molecules that life could use — but doesn't."
CHICAGO — A strange, new genetic code a lot like that found in all terrestrial life is sitting in a beaker full of oily water in a laboratory in Florida, a scientist said today, calling it the first example of an artificial chemical system that is capable of Darwinian evolution.
The system is made of the four molecules that are the basic building blocks of our DNA along with eight synthetic modifications of them, said biochemist Steven A. Benner of the Foundation for Applied Molecular Evolution in Gainesville.
The main difference between the synthetic molecules and those that make up conventional DNA is that Benner's molecules cannot make copies of themselves, although that is just "a couple of years" away, he said.
The wild biochemistry finding, described to a small group of reporters today at the annual meeting of the American Association for the Advancement of Science, offers ideas about new types of life for scientists to look for beyond our planet, or even possibly hidden on our planet.
"Unless it happens to shoot at you with a ray gun, the life that you encounter off of Earth will not necessarily have same biochemistry as us," Benner said.
And the step from Benner's system to something that could be called artificial life is still large. "There is not enough information in them to build organisms," Benner said.
Expanded alphabet for DNA
For some 20 years, Benner's labs have been involved in trying to make artificial life or things approximating it, with similar genetic and inheritance properties to life on Earth. (Previously, Benner worked at the University of Florida.)
He and his colleagues have focused in part on expanding the DNA alphabet to develop an "Artificially Expanded Genetic Information System," which now has its own supporting molecular biology.
The building blocks of DNA are four chemicals called nucleotides that are referred to as A, C, T and G, for short. The nucleotides pair up and bond in predictable ways to form the double helix structure of DNA. Benner's new nucleotides, which he and his colleagues have named Z, P, V, J, Iso-C, Iso-G, X and K, are reshufflings of the constituents of those molecules found in our DNA.
The evolution in this system happens when the 12-letter genetic code makes copying mistakes and subsequent sequences have properties that make them more liable to get copied. Those sequences would survive in greater numbers than the original sequence.
Benner's synthetic approach was conceptualized using "ball and stick plastic model chemistry," he said, the technique used by James Watson and Francis Crick to arrive at the structure of the DNA molecule in 1953.
The human genome's DNA includes 3 billion base pairs. Some of the molecules synthesized in Benner's lab are 81 base pairs long — relatively short.
The molecules are "fed" and grow via a process called the polymerase chain reaction (PCR) that allows the molecules to make copies of themselves. Once the replication of the molecules in Benner's system is self-catalyzed, without PCR, the process is self-sustaining. Benner claims, "then it's artificial life."
Dreaming up extra-terrestrial life
The research resulted from a NASA-funded project to try to understand what life might look like beyond Earth. Such life might live in water, but it could also live in liquid nitrogen or methane (as speculated for Saturn's moon Titan) and in environments with extremely high or low acidity.
The results are published in a technical book, "Life, the Universe and the Scientific Method," of which Benner has made about 100 copies to distribute to his colleagues.
"One of the ways scientists try to understand life as a universal concept ... is you try to make life on your own in the lab," Benner said. "We try to put together chemicals that do that."
Any potential life forms made from such molecules would be "so alien in terms of their biochemistry that they will not able to eat you," Benner said.
NASA has been involved in searching for extra-terrestrial life along numerous avenues for decades, including the Viking mission to Mars in the 1970s and its recent missions to the red planet which have searched for signs of habitability there. NASA also funds an Astrobiology Institute, which partners with hundreds of researchers world-wide who study of the origins, evolution, distribution and future of life in the universe
The trick to searching for alien life is how to look for it, said Paul Davies of Arizona State University, who also spoke with reporters here today.
"All of the techniques which microbiologists use to [look for alien life] are customized to life as we know it," Davies said. "It's no surprise that microbiologists haven't come across micro-organisms that seem to have relatively different biochemistry."
In the future, more scientists could "talk with Steve Benner," Davies said, "to come up with perfectly good molecules that life could use — but doesn't."
Subscribe to:
Posts (Atom)