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Toxins may pass down generations
Toxic chemicals that poisoned your great-grandparents may also damage your health, US research suggests.
Dr Michael Skinner, BBC News
A team from Washington State University has produced evidence that some inherited diseases may be caused by poisons polluting the womb.
Research on rats indicates man-made environmental toxins may alter genetic activity, giving rise to diseases that pass down at least four generations.
The research is published in the journal Science.
The scientists exposed pregnant rats to two agricultural chemicals during the period that the sex of their offspring was being determined.
The compounds were vinclozolin, a fungicide commonly used in vineyards, and the pesticide methoxychlor.
Both are known as endocrine disruptors - chemicals that interfere with the normal functioning of reproductive hormones.
Rats exposed to the compounds produced male offspring with low sperm counts and poor fertility.
They were still able to produce young, however. When these rats were then mated with females that had not been exposed to the toxins, their male offspring had the same problems.
The effect persisted through at least four generations, impairing the fertility of more than 90% of male offspring in each generation.
The researchers found the damage was not caused by alterations in the DNA code, but changes in the way the genes work.
These epigenetic changes, as they are known, are caused by small chemicals that become attached to the DNA, modifying its activity.
Epigenetic changes have been observed before - but were not previously known to pass onto later generations.
Cancer clue
Lead researcher Dr Michael Skinner believes they may contribute to diseases such as breast cancer and prostate cancer.
Both diseases are becoming more common, and Dr Skinner says that cannot be down to genetic mutations alone.
The researchers believe their findings suggest exposure to environmental toxins may play a key role in the evolutionary process.
Evolution may not be driven entirely by genetic mutations, as commonly thought.
Dr Skinner said: "It is a new way to think about disease. We believe this phenomenon will be widespread and be a major factor in understanding how disease develops."
However, Dr Skinner stressed more work was needed to corroborate the findings.
The levels of chemicals the rats were exposed to were very high - much higher than people normally ever encounter.
Professor Alan Boobis, a toxicologist at Imperial College London, UK, told the BBC News website the findings were interesting, but he said there was no need for people to be alarmed.
"This effect is likely to be concentration dependent, and these animals were exposed to very high levels of chemicals," he said.
"We need to find out whether this trans-generational effect is translated to much lower doses."
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/4605847.stm
Drawing uncovered of 'Nazi nuke'
Historians working in Germany and the US claim to have found a 60-year-old diagram showing a Nazi nuclear bomb.
BBC NEWS
It is the only known drawing of a "nuke" made by Nazi experts and appears in a report held by a private archive.
The researchers who brought it to light say the drawing is a rough schematic and does not imply the Nazis built, or were close to building, an atomic bomb.
But a detail in the report hints some Nazi scientists may have been closer to that goal than was previously believed.
The report containing the diagram is undated, but the researchers claim the evidence points to it being produced immediately after the end of the war in Europe. It deals with the work of German nuclear scientists during the war and lacks a title page, so there is no evidence of who composed it.
One historian behind the discovery, Rainer Karlsch, caused a storm of controversy earlier this year when he claimed to have uncovered evidence that the Nazis successfully tested a primitive nuclear device in the last days of WWII. A number of historians rejected the claim.
The drawing is published in an article written for Physics World magazine by Karlsch and Mark Walker, professor of history at Union College in Schenectady, US.
'Mini-nuke'
The newly uncovered document was discovered after the publication of Karlsch's book, Hitlers Bombe (Hitler's Bomb), in which he made the nuclear test claim.
"The Nazis were far away from a 'classic' atomic bomb. But they hoped to combine a 'mini-nuke' with a rocket," Dr Karlsch told the BBC News website.
"The military believed they needed around six months more to bring the new weapon into action. But the scientists knew better how difficult it was to get the enriched uranium required."
The head of Nazi Germany's nuclear energy programme was the physicist Werner Heisenberg. Though he was highly accomplished in other areas of physics, Heisenberg failed to understand a key aspect of nuclear fission chain reactions.
Heisenberg's uncertainty
Some researchers say this led him to overestimate the amount of uranium - the so-called fissile material - required to build a nuclear bomb.
However, the German report contains an estimate of slightly more than 5kg for the critical mass of a plutonium bomb. This is comparatively close to the real figure and may suggest some Nazi scientists had a better grasp of nuclear fission than Heisenberg.
Professor Paul Lawrence Rose, of Pennsylvania State University, US, and author of a 1998 book about the German uranium programme, said he had no reason to believe the report was not genuine, but was dubious about the significance of the critical mass detail.
"Though it's wonderful to find the 5kg figure written on the document, one has to be sceptical about the rationale for it. Even if it's true and [some scientists] did understand it, Heisenberg's group wouldn't have accepted it," Rose told the BBC News website.
He further speculated it was possible the author arrived at this figure by reading the Smyth Report into the development of the US atomic bomb, which was published in July 1945. But Karlsch and Walker reject this claim.
Bombshell claim
In Hitlers Bombe, Dr Karlsch suggests a team of scientists directed by the physicist Kurt Diebner, which was in competition with Heisenberg's group, tested a primitive nuclear device in Thuringia, eastern Germany, in March 1945.
Rose says that this is unlikely. Transcripts of conversations taped by MI6 when the scientists were held captive in England after the war showed Diebner lacked the knowledge to have done this, he says.
"Karlsch revealed some very important details in his book, but I can't go along with the picture he constructs with those details - of a Nazi nuclear test," said Professor Dieter Hoffmann, of the Max Planck Institute for the History of Science, in Berlin.
But in their Physics World article, Karlsch and Walker point to evidence of innovations made by Diebner's team, including a nuclear reactor design superior to that produced by Heisenberg's group.
"[Diebner] got the research papers from all other groups and he could control the information flux. Only a few scientists around Diebner knew about his bomb project. Heisenberg was not aware of it," Dr Karlsch explained.
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/4598955.stm
Extinct cave bear DNA sequenced
By Helen Briggs, BBC News science reporter, BBC NEWS
Scientists have extracted and decoded the DNA of a cave bear that died 40,000 years ago.
They plan to unravel the DNA of other extinct species, including our closest ancient relatives, the Neanderthals.
But they say the idea of obtaining DNA from dinosaurs, depicted in the film Jurassic Park, remains science fiction.
It is highly unlikely that viable genetic material will ever be recovered from fossils that are hundreds of millions of years old.
But the scientists hope to be able to sequence the DNA of ancient humans, which lived at the same time as cave bears, raising the prospect of perhaps one day being able to "build" a Neanderthal from their genetic blueprint.
Jurassic Park
"In hundreds or thousands of years from now, we may have advanced our technology so we can create creatures from DNA sequence information," Dr Eddy Rubin, director of the US Department of Energy Joint Genome Institute in Walnut Creek, California, told the BBC News website.
"I don't think we can extract DNA from dinosaurs; I think they are too old. As for creating Jurassic Park, I think that remains science fiction."
The scientists extracted DNA from the tooth and bones of cave bears found at two sites in Austria.
The cave bear was once common in Europe but died out about 10,000 years ago, when the forests shrank at the end of the last Ice Age.
Dr Rubin's team analysed the extinct bear's DNA using powerful computing technology developed during the human genome project.
This approach has been hampered in the past by the fact that ancient DNA is contaminated with genetic material from bacteria and people who have handled the ancient remains.
Sifting out the ancient DNA from this genetic soup is like looking for a needle in a haystack.
But because we now know the genetic sequences of many organisms - including numerous microbes, the human, and animals such as the dog - the researchers were able to isolate the sequences they were interested in.
In the case of the cave bear, they used the sequence of the dog, which exists in public databases, and the DNA of modern bears, as a "magnet".
Dr Rubin said it served as a "proof of principle" that the method works.
They are now turning their attention to the Neanderthals, the closest ancient relatives of modern humans, who lived around the same time as the bears.
"I think it will work," he said. "It is just a matter of time."
Mitochondrial DNA
Most fossils are of no use to scientists hunting ancient biomolecules. It is only in those specimens where some sub-fossil material - tissues that have not been fully mineralised - still exists that researchers can hope to retrieve some genetic information.
And in the last few years, a number of labs have developed the expertise to extract fragments of DNA from animals that died out tens of thousands of years ago.
Most of these samples, though, have been from mitochondria, the structures in the cell that produce energy and have their own genetic material.
While this can provide valuable information about the evolutionary history of a species, it is the DNA within the nucleus, the nuclear or genomic DNA, which contains the bulk of an animal's genetic information, including the secrets of how modern animals differ from their ancestors.
Dr Dan Bradley, an expert on ancient DNA at Trinity College, Dublin, Ireland, said the research was "very encouraging".
"It has been very difficult thus far to get anything other than mitochondrial DNA from ancient material," he said.
"That is only a very small part of our DNA with limited interest."
The research is reported in the journal Science.
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/4602739.stm
How blood disorder blocks malaria
Scientists believe they have uncovered why people with a gene for a blood disorder are immune to malaria.
BBC NEWS
It is known that people with a single gene for sickle cell anaemia, but not the full-blown condition, are somewhat resistant to the malaria parasite.
Some say the distorted red blood cells caused by the gene are broken down quicker than normal by the body so malaria has no home in which to thrive.
Now a Wellcome Trust team suggests the immune system also plays a big role.
By studying more than 1,000 children living on the coast of Kenya, where malaria is rife, they found many with the sickle cell trait developed increasing protection against malaria as they aged.
Between the ages of two and 10, immunity to the disease rose rapidly.
The protection against malaria was around 20% in the first two years of life compared with over 50% by the age of 10, the researchers report in the journal PLoS Medicine.
However, protection is not 100%, so people with the trait still need to be aware of the risks of malaria, they stressed.
Lead researcher Dr Tom Williams said: "It has been known for some time that sickle cell trait offers this protection, but the accelerated level of immunity in the first years of life has not been revealed before."
He said there were several possible reasons why this happened, but that further research was needed to know for sure.
One explanation might be that although the bulk of blood cells carrying malaria are destroyed quickly, a few may escape destruction - but not enough to cause malaria symptoms.
This would allow the immune system time to gradually build up an effective defence against malaria, he suggested.
He cautioned that his team had studied only mild malaria, which causes fever and does not kill.
"We do not know if our findings can be applied to severe forms of malaria, which can lead to death," he said.
Dr Colin Sutherland, of the Health Protection Agency's Malaria Reference Laboratory at the London School of Hygiene & Tropical Medicine, said: "This work has provided us with tantalising evidence that mild sickle cell trait does more than just impede the malaria parasite's growth in the abnormal red cell, it actually enhances the child's acquisition of specific anti-malaria immunity.
'New model'
'"If these results are confirmed by further studies, then children with the mild form of sickle cell anaemia will have provided a new model for understanding the natural process of becoming immune to malaria."
Sickle cell trait occurs when someone inherits a normal gene from one parent and a sickle cell gene from the other parent.
Children with sickle cell trait do not usually display the symptoms of those with full-blown sickle cell anaemia, such as breathlessness and bone and joint pain.
In sickle cell disease, the major protein in red blood cells that carries oxygen around the body, haemoglobin, is different from normal.
Although it can still carry oxygen, the red blood cells tend to distort into a sickle shape, instead of a doughnut shape, and can disrupt smooth blood flow, which leads to complications.
Sickle cell anaemia:
-Inherited disorder affecting red blood cells
-Named after scythe-type shape of red blood cells
-Those with two faulty genes have full-blown disease
-Those with only one copy have "sickle cell trait"
-More common in African and Afro-Caribbean people and malarious areas
-Children with sickle cell trait do not usually display symptoms of full-blown sickle cell anaemia, such as breathlessness and bone and joint pain
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/4587311.stm
Toxic chemicals that poisoned your great-grandparents may also damage your health, US research suggests.
Dr Michael Skinner, BBC News
A team from Washington State University has produced evidence that some inherited diseases may be caused by poisons polluting the womb.
Research on rats indicates man-made environmental toxins may alter genetic activity, giving rise to diseases that pass down at least four generations.
The research is published in the journal Science.
The scientists exposed pregnant rats to two agricultural chemicals during the period that the sex of their offspring was being determined.
The compounds were vinclozolin, a fungicide commonly used in vineyards, and the pesticide methoxychlor.
Both are known as endocrine disruptors - chemicals that interfere with the normal functioning of reproductive hormones.
Rats exposed to the compounds produced male offspring with low sperm counts and poor fertility.
They were still able to produce young, however. When these rats were then mated with females that had not been exposed to the toxins, their male offspring had the same problems.
The effect persisted through at least four generations, impairing the fertility of more than 90% of male offspring in each generation.
The researchers found the damage was not caused by alterations in the DNA code, but changes in the way the genes work.
These epigenetic changes, as they are known, are caused by small chemicals that become attached to the DNA, modifying its activity.
Epigenetic changes have been observed before - but were not previously known to pass onto later generations.
Cancer clue
Lead researcher Dr Michael Skinner believes they may contribute to diseases such as breast cancer and prostate cancer.
Both diseases are becoming more common, and Dr Skinner says that cannot be down to genetic mutations alone.
The researchers believe their findings suggest exposure to environmental toxins may play a key role in the evolutionary process.
Evolution may not be driven entirely by genetic mutations, as commonly thought.
Dr Skinner said: "It is a new way to think about disease. We believe this phenomenon will be widespread and be a major factor in understanding how disease develops."
However, Dr Skinner stressed more work was needed to corroborate the findings.
The levels of chemicals the rats were exposed to were very high - much higher than people normally ever encounter.
Professor Alan Boobis, a toxicologist at Imperial College London, UK, told the BBC News website the findings were interesting, but he said there was no need for people to be alarmed.
"This effect is likely to be concentration dependent, and these animals were exposed to very high levels of chemicals," he said.
"We need to find out whether this trans-generational effect is translated to much lower doses."
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/4605847.stm
Drawing uncovered of 'Nazi nuke'
Historians working in Germany and the US claim to have found a 60-year-old diagram showing a Nazi nuclear bomb.
BBC NEWS
It is the only known drawing of a "nuke" made by Nazi experts and appears in a report held by a private archive.
The researchers who brought it to light say the drawing is a rough schematic and does not imply the Nazis built, or were close to building, an atomic bomb.
But a detail in the report hints some Nazi scientists may have been closer to that goal than was previously believed.
The report containing the diagram is undated, but the researchers claim the evidence points to it being produced immediately after the end of the war in Europe. It deals with the work of German nuclear scientists during the war and lacks a title page, so there is no evidence of who composed it.
One historian behind the discovery, Rainer Karlsch, caused a storm of controversy earlier this year when he claimed to have uncovered evidence that the Nazis successfully tested a primitive nuclear device in the last days of WWII. A number of historians rejected the claim.
The drawing is published in an article written for Physics World magazine by Karlsch and Mark Walker, professor of history at Union College in Schenectady, US.
'Mini-nuke'
The newly uncovered document was discovered after the publication of Karlsch's book, Hitlers Bombe (Hitler's Bomb), in which he made the nuclear test claim.
"The Nazis were far away from a 'classic' atomic bomb. But they hoped to combine a 'mini-nuke' with a rocket," Dr Karlsch told the BBC News website.
"The military believed they needed around six months more to bring the new weapon into action. But the scientists knew better how difficult it was to get the enriched uranium required."
The head of Nazi Germany's nuclear energy programme was the physicist Werner Heisenberg. Though he was highly accomplished in other areas of physics, Heisenberg failed to understand a key aspect of nuclear fission chain reactions.
Heisenberg's uncertainty
Some researchers say this led him to overestimate the amount of uranium - the so-called fissile material - required to build a nuclear bomb.
However, the German report contains an estimate of slightly more than 5kg for the critical mass of a plutonium bomb. This is comparatively close to the real figure and may suggest some Nazi scientists had a better grasp of nuclear fission than Heisenberg.
Professor Paul Lawrence Rose, of Pennsylvania State University, US, and author of a 1998 book about the German uranium programme, said he had no reason to believe the report was not genuine, but was dubious about the significance of the critical mass detail.
"Though it's wonderful to find the 5kg figure written on the document, one has to be sceptical about the rationale for it. Even if it's true and [some scientists] did understand it, Heisenberg's group wouldn't have accepted it," Rose told the BBC News website.
He further speculated it was possible the author arrived at this figure by reading the Smyth Report into the development of the US atomic bomb, which was published in July 1945. But Karlsch and Walker reject this claim.
Bombshell claim
In Hitlers Bombe, Dr Karlsch suggests a team of scientists directed by the physicist Kurt Diebner, which was in competition with Heisenberg's group, tested a primitive nuclear device in Thuringia, eastern Germany, in March 1945.
Rose says that this is unlikely. Transcripts of conversations taped by MI6 when the scientists were held captive in England after the war showed Diebner lacked the knowledge to have done this, he says.
"Karlsch revealed some very important details in his book, but I can't go along with the picture he constructs with those details - of a Nazi nuclear test," said Professor Dieter Hoffmann, of the Max Planck Institute for the History of Science, in Berlin.
But in their Physics World article, Karlsch and Walker point to evidence of innovations made by Diebner's team, including a nuclear reactor design superior to that produced by Heisenberg's group.
"[Diebner] got the research papers from all other groups and he could control the information flux. Only a few scientists around Diebner knew about his bomb project. Heisenberg was not aware of it," Dr Karlsch explained.
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/4598955.stm
Extinct cave bear DNA sequenced
By Helen Briggs, BBC News science reporter, BBC NEWS
Scientists have extracted and decoded the DNA of a cave bear that died 40,000 years ago.
They plan to unravel the DNA of other extinct species, including our closest ancient relatives, the Neanderthals.
But they say the idea of obtaining DNA from dinosaurs, depicted in the film Jurassic Park, remains science fiction.
It is highly unlikely that viable genetic material will ever be recovered from fossils that are hundreds of millions of years old.
But the scientists hope to be able to sequence the DNA of ancient humans, which lived at the same time as cave bears, raising the prospect of perhaps one day being able to "build" a Neanderthal from their genetic blueprint.
Jurassic Park
"In hundreds or thousands of years from now, we may have advanced our technology so we can create creatures from DNA sequence information," Dr Eddy Rubin, director of the US Department of Energy Joint Genome Institute in Walnut Creek, California, told the BBC News website.
"I don't think we can extract DNA from dinosaurs; I think they are too old. As for creating Jurassic Park, I think that remains science fiction."
The scientists extracted DNA from the tooth and bones of cave bears found at two sites in Austria.
The cave bear was once common in Europe but died out about 10,000 years ago, when the forests shrank at the end of the last Ice Age.
Dr Rubin's team analysed the extinct bear's DNA using powerful computing technology developed during the human genome project.
This approach has been hampered in the past by the fact that ancient DNA is contaminated with genetic material from bacteria and people who have handled the ancient remains.
Sifting out the ancient DNA from this genetic soup is like looking for a needle in a haystack.
But because we now know the genetic sequences of many organisms - including numerous microbes, the human, and animals such as the dog - the researchers were able to isolate the sequences they were interested in.
In the case of the cave bear, they used the sequence of the dog, which exists in public databases, and the DNA of modern bears, as a "magnet".
Dr Rubin said it served as a "proof of principle" that the method works.
They are now turning their attention to the Neanderthals, the closest ancient relatives of modern humans, who lived around the same time as the bears.
"I think it will work," he said. "It is just a matter of time."
Mitochondrial DNA
Most fossils are of no use to scientists hunting ancient biomolecules. It is only in those specimens where some sub-fossil material - tissues that have not been fully mineralised - still exists that researchers can hope to retrieve some genetic information.
And in the last few years, a number of labs have developed the expertise to extract fragments of DNA from animals that died out tens of thousands of years ago.
Most of these samples, though, have been from mitochondria, the structures in the cell that produce energy and have their own genetic material.
While this can provide valuable information about the evolutionary history of a species, it is the DNA within the nucleus, the nuclear or genomic DNA, which contains the bulk of an animal's genetic information, including the secrets of how modern animals differ from their ancestors.
Dr Dan Bradley, an expert on ancient DNA at Trinity College, Dublin, Ireland, said the research was "very encouraging".
"It has been very difficult thus far to get anything other than mitochondrial DNA from ancient material," he said.
"That is only a very small part of our DNA with limited interest."
The research is reported in the journal Science.
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/4602739.stm
How blood disorder blocks malaria
Scientists believe they have uncovered why people with a gene for a blood disorder are immune to malaria.
BBC NEWS
It is known that people with a single gene for sickle cell anaemia, but not the full-blown condition, are somewhat resistant to the malaria parasite.
Some say the distorted red blood cells caused by the gene are broken down quicker than normal by the body so malaria has no home in which to thrive.
Now a Wellcome Trust team suggests the immune system also plays a big role.
By studying more than 1,000 children living on the coast of Kenya, where malaria is rife, they found many with the sickle cell trait developed increasing protection against malaria as they aged.
Between the ages of two and 10, immunity to the disease rose rapidly.
The protection against malaria was around 20% in the first two years of life compared with over 50% by the age of 10, the researchers report in the journal PLoS Medicine.
However, protection is not 100%, so people with the trait still need to be aware of the risks of malaria, they stressed.
Lead researcher Dr Tom Williams said: "It has been known for some time that sickle cell trait offers this protection, but the accelerated level of immunity in the first years of life has not been revealed before."
He said there were several possible reasons why this happened, but that further research was needed to know for sure.
One explanation might be that although the bulk of blood cells carrying malaria are destroyed quickly, a few may escape destruction - but not enough to cause malaria symptoms.
This would allow the immune system time to gradually build up an effective defence against malaria, he suggested.
He cautioned that his team had studied only mild malaria, which causes fever and does not kill.
"We do not know if our findings can be applied to severe forms of malaria, which can lead to death," he said.
Dr Colin Sutherland, of the Health Protection Agency's Malaria Reference Laboratory at the London School of Hygiene & Tropical Medicine, said: "This work has provided us with tantalising evidence that mild sickle cell trait does more than just impede the malaria parasite's growth in the abnormal red cell, it actually enhances the child's acquisition of specific anti-malaria immunity.
'New model'
'"If these results are confirmed by further studies, then children with the mild form of sickle cell anaemia will have provided a new model for understanding the natural process of becoming immune to malaria."
Sickle cell trait occurs when someone inherits a normal gene from one parent and a sickle cell gene from the other parent.
Children with sickle cell trait do not usually display the symptoms of those with full-blown sickle cell anaemia, such as breathlessness and bone and joint pain.
In sickle cell disease, the major protein in red blood cells that carries oxygen around the body, haemoglobin, is different from normal.
Although it can still carry oxygen, the red blood cells tend to distort into a sickle shape, instead of a doughnut shape, and can disrupt smooth blood flow, which leads to complications.
Sickle cell anaemia:
-Inherited disorder affecting red blood cells
-Named after scythe-type shape of red blood cells
-Those with two faulty genes have full-blown disease
-Those with only one copy have "sickle cell trait"
-More common in African and Afro-Caribbean people and malarious areas
-Children with sickle cell trait do not usually display symptoms of full-blown sickle cell anaemia, such as breathlessness and bone and joint pain
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/4587311.stm
