tagged w/ RNA
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Did a recent scientific study just change the way we should think about the safety of genetically modified foods? According to Ari Levaux at the Atlantic, the answer is a resounding yes.
The study in question, performed by researchers at China’s Nanjing University and published in the journal Cell Research, found that a form of genetic material — called microRNA — from conventional rice survived the human digestive process and proceeded to affect cholesterol function in humans.
Levaux argues that this new study “reveals a pathway by which genetically modified (GM) foods might influence human health” which should cause us to completely revisit the question of GM crops’ safety. And he’s right to be alarmed, just a little off on the reasoning.
Let’s take a closer look at how this study applies to current GM technology, shall we?
I would argue that several studies have already suggested that existing GM foods might present a health risk. For example, this study in The International Journal of Biological Sciences found evidence that Monsanto’s Bt corn causes organ damage in lab animals. Then there’s this one which showed that GM soybeans can alter mice on the cellular level — an indication that genetically modified material survives digestion and is active in animals that consume it.
Of course, advocates of genetically modified foods will observe that the phenomenon of genetic transfer through consumption applies to all plants and that GM foods are therefore “substantially equivalent” to non-GM foods. As Levaux explains at length, this concept of substantial equivalence has been used by the biotech industry as well as our government to push GM foods through safety testing with minimal scrutiny. What’s Monsanto’s defense of all this? On its website, the company claims:
There is no need to test the safety of DNA introduced into GM crops. DNA (and resulting RNA) is present in almost all foods … DNA is non-toxic and the presence of DNA, in and of itself, presents no hazard … So long as the introduced protein is determined to be safe, food from GM crops determined to be substantially equivalent is not expected to pose any health risks.
So the fact that the Chinese team found active genetic material going from plants to humans isn’t really new and doesn’t really change what we know about how existing genetically engineered crops might affect us.
But what is new — and what Levaux missed — is that the Chinese study happens to involve exactly the kind of genetic matrieral — microRNA — that biotech companies hope to use in their next generation of genetically modified foods.
Today’s GMOs are almost entirely based on adding new genes to crops like corn, soy, and cotton in order to alter the way the plants function. And even then new functions are mostly limited to making plants either able to tolerate herbicides or to produce their own. But if biotechnology companies are successful in their efforts, there may soon be genetically modified foods that use microRNA — simply put, snippets of RNA whose potency were only discovered around a decade ago — to target, and block the function of specific genes in pests.
Thus the news that plant microRNA can survive digestion and affect human systems brings into question the wisdom of pursuing this kind of technology in food.
As explained to me by Doug Gurian-Sherman, senior scientist for the Union of Concerned Scientists and expert in genetically modified foods, microRNA technology is an area that biotech companies are actively pursuing. Monsanto itself has a whole web page devoted to the technology, which they call RNA interference.
Gurian-Sherman notes that the Chinese study — though requiring confirmation and follow-up research — raises “an initial red flag.” It calls into question “any general statement that [microRNA] technology would be inherently safe,” he adds.
He observes that humans and insects share a surprising amount of DNA material — evolution favors reusing and recycling genes even among creatures as different as insects and humans. If this research bears out, then it’s entirely possible that microRNA meant to target a specific insect gene will also have an effect — possibly unpredictable — in humans. This is especially true because, for technology like this to work as a pesticide, the microRNA must be present in high levels in the plant, which makes it even more likely the genetic material will make it all the way into the human gut.
snip
UPDATE: Dr. Michael Hansen, Senior Scientist at Consumers Union wrote to me after this post was published with an important point about the significance of the Chinese study. While he agreed that the main implications relate to the possible risk from microRNA-based GM foods, he also felt that this study did make a new and somewhat startling finding regarding how plant genetic material affects humans. As he put it, the study “showed that the miRNA not only survived digestion [in humans] but also was taken up and moved to other parts of the body where a specific impact was noted. The studies you cited — from Seralini’s lab and Malatesta’s lab — only show that GE crops can have an adverse effect on animals.”
more at the linkDid a recent scientific study just change the way we should think about the safety of... more
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Scientists in Scotland have discovered a "missing link" which helps them understand how human cells decode genes important for cell growth and multiplication.
The University of Dundee researchers are studying the process of transcription, in which cells copy the DNA of genes into Ribonucleic acid or RNA, ultimately leading to the manufacture of proteins.
RNA is one of the three major macromolecules - along with DNA and proteins - that are essential for all known forms of life.
Transcription must be tightly controlled because otherwise the cells can die or grow and multiply without restraint, as seen in certain human diseases including cancer.
Dr Joost Zomerdijk and his team have discovered a previously hidden link within the components of the transcription machinery.
He said: "My lab and I are extremely excited to have discovered this important missing link.
"Furthermore, this research, funded primarily by the Wellcome Trust, advances our understanding of how normal transcription is maintained and controlled in human cells, which will help us to work out how transcription becomes deregulated in certain diseased cells and, potentially, how we can reverse such deregulation."
Human cells contain three separate transcription machineries, each of which is important for transcription of a subset of genes within the cells.
Each of the three is made up of one specific RNA polymerase enzyme and several other groups of proteins that direct and control transcription activity.
While TFIIB proteins, or similar proteins, were found in the transcription machineries containing RNA polymerases II and III, a similar protein had not been identified as a component of the RNA polymerase I transcription machinery.
However the scientists have now discovered that the protein TAF1B, one of a group of proteins that directs the RNA polymerase I enzyme, is similar to TFIIB in structure and function.
Dr Zomerdijk said: "This discovery indicates that the three transcription machineries of human cells, which are likely to have evolved from a common ancestor, are even more similar than previously realised."
He and his colleagues work at the Wellcome Trust Centre for Gene Regulation and Expression in the College of Life Sciences at Dundee University.
Details of their findings are being published in a research paper in the journal Science.Scientists in Scotland have discovered a "missing link" which helps them... more
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pdy
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9 months ago
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I can’t believe the number of things you can find out about yourself by spitting in a cup. A recent study at UCLA demonstrated that certain strands of micro RNA (miRNA) found in your saliva could indicate the presence of oral carcinoma.
The work was published in Clinical Cancer Research, a journal of the American Association for Cancer Research. Doctors may have found a quick and easy way to routinely scan patients for oral cancer without the need for biopsy, which would mean a better chance of early detection. That’s good news for the tobacco chewers, who make up about 75% of all oral cancer patients in the US.
As with so many cancers, oral carcinoma is very survivable if found early. The problem is that low public awareness keeps most people from seeking a routine examination, even if they partake in high risk behavior. While current diagnosis for oral cancer is actually quite quick and painless, the measurements of miRNA in spit could allow the test to be taken along with others.
Already we’ve seen how breathalysers can detect lung cancer. Perhaps all our cancer risks may one day be assessed just by opening our mouths.I can’t believe the number of things you can find out about yourself by spitting... more
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photi
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2 years ago
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Scientist are seceptical of news that states a man who under went a bone marrow transplant to treat an unrelated acute myeloid leukemia.
The man specifically sought out a donor who had a defective CCR5 receptor which are protected against the virus.
People with two copies of the CCR5 mutation, dubbed delta32, are relatively rare -- only about one in 100 people in Central Europe, Dr. Hütter said in February.
Among the 232 HLA-matched donors found by the German Central Bone Marrow Donor Registry, the researchers found one with the double CCR5 mutation.
The transplant itself was without incident, the researchers said, with standard regimens to prevent graft-versus-host disease, and engraftment was achieved by day 13.
"The patient managed transplantation and engraftment without any remarkable irregularities," the researchers said.
The man's HIV treatment was stopped from the day of transplantation and has not been resumed. His immune cells were completely converted to the new CCR5 pattern by day 60 and there was no sign of HIV RNA or proviral DNA after day 68.
But specialists -- and even Dr. Hütter -- are cautioning that a bone marrow transplant is too dangerous and too expensive to be considered as a routine treatment for HIV.
So the question is are people willing to dish out the cash and take the risk for a possible cure?Scientist are seceptical of news that states a man who under went a bone marrow... more
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A new way to reveal the genesis of all life, the deepest question in biology, has been devised by scientists.
Many experts believe that the first kinds of life depended on RNA, a more flexible kind of genetic material than the DNA that today carries genes for most life on Earth.
Now an American team proposes that a study be carried out of proteins that viruses and other parasites use to pirate DNA, and convert it into RNA, to reveal details of the kind of RNA genetic machinery that must have been present in the first life, which is estimated to have emerged about four billion years ago.
The team at The Pennsylvania State University, Penn State, focuses on proteins such as the enzyme reverse transcriptase, which is used by the Aids virus (written in RNA) to alter the DNA or genetic material of an infected cell to produce more virus particles.
There are many more examples, since half the human genetic code, previously thought to be meaningless junk, is actually composed of sequences for these related ancient proteins, called retroelements.
Aside from the reverse transcriptases of viruses, there are retrotransposons, which are virus like genetic elements that are thought to play a role in evolution by generating diversity in the genetic code, as well as telomerases, enzymes that play a basic role in the ageing of animals.
By tracking the similarities between these proteins, which sit at the boundary between the RNA world, and the one written in DNA, has the potential to trace the evolutionary histories of proteins all the way back to either cells or viruses, thus settling the debate once and for all over which of these life forms came first, RNA based or DNA based.
"We have just begun to tap the potential power of this method," said Dr Randen Patterson. "We believe, if it is possible at all, that it is within our grasp to determine whether viruses evolved from cells or vice-versa."
The new computational method is described in the journal Proceedings of the National Academy of Sciences and creates a tree-like diagram, called a phylogenetic tree, based on the retroelements' similarities to one another.
According to Dr Damian van Rossum, coauthor, the new method can be used in conjunction with the conventional method to get a clearer picture of the evolutionary histories of proteins. "The more independent measures you have, the better view of the world you can get," he said.
The tree provides evolutionary distance estimates and, hence, relationships among retroelements: the more similar they are, the more recent the common ancestor.
By the same token, a survey of the most distantly related retroelements could help them estimate the age and the function of the most ancient, perhaps even at the moment of genesis.A new way to reveal the genesis of all life, the deepest question in biology, has been... more
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Working in mice infected with HIV, a team used a method called RNA interference to knock down three genes in T cells, protecting them from the virus. This method seemed to prevent HIV from jumping between cells in the mice.
"For the first time, we've used RNAi to dramatically suppress HIV infection in an organism," says corresponding author Premlata Shankar, who conducted the work while she was a junior investigator at the Harvard Medical School-affiliated Immune Disease Institute and an assistant professor at Harvard Medical School. Shankar is now a professor at Texas Tech University Health Sciences Center in El Paso.Working in mice infected with HIV, a team used a method called RNA interference to... more
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bshipp
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3 years ago
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