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Comment Re:DNA Data Storage (Score 1) 204

When I mentioned DNA from millenia ago, I was referring to scientists being able sequence DNA from the remains of dead, extinct animals (like the woolly mammoth genome). In the Science paper, they print the DNA onto a microchip which can be easily read out with standard DNA sequencing machines. Storing information in the DNA of a living organism would, of course, not work very well because of the low but significant error rate of DNA replication.

Comment DNA Data Storage (Score 3, Interesting) 204

Last year George Church and colleagues published a paper in Science describing data storage using DNA (Church, Gao, and Kosuri. 2012. Next-Generation Digital Information Storage in DNA. Science 337: 1628. doi:10.1126/science.1226355) . While perhaps not lasting billions of years, given that we've been able to read DNA from creatures that existed millenia ago (whose DNA was definitely stored in non-ideal conditions), DNA data storage could potentially preserve data for very long periods of time.

Comment Happend with the papaya in Hawaii (Score 2) 358

A similar situation occurred with the papaya ringspot virus threatening to devastate the papaya industry in Hawaii. However, in 1998, researchers developed a genetically modified papaya resistant to the virus, and this scientific development has been credited with saving Hawaii's papaya industry. Perhaps this offers some hope for a good outcome in using genetic modification to solve the problem of citrus greening.

Comment Re:Why was that viral gene inside in the first pla (Score 5, Informative) 391

1. Why is that viral gene in there?

When you insert a new gene (such as an herbicide resistance gene in Monsanto's Roundup Ready crops) into a plant, you also need to insert a piece of DNA called a promoter that tells the plant to turn the gene on. The scientists who created the GMOs chose to insert the promoter from the cauliflower mosaic virus (CaMV), as it is particularly good at this task and is very well studied. This promoter also happens to include part, but not the entirety, of gene VI from the virus.

* 2. Was it put there by accident or by purpose? * 2(a). If by accident, how, when, what happened? * 2(b). If by purpose, why, and by whom?

As stated above, the fragment of gene VI was placed into the GMOs on purpose. Because fragments of genes are generally inactive, the presence of the gene fragment is not expected to be problematic and showed no evidence of causing problems during the testing of the GMOs. Furthermore, because cauliflower mosaic virus is a naturally occurring virus, the full gene VI can be found in many non-GMO crops (for example, see this 2004 study).

3. How come the American scientists never detected this viral gene? * 3(a). Was it because of incompetence, or was it because the American scientists were not allowed to publish their finding, if they had found it before the Europeans?

These findings were not published before because we already knew that many GMOs contain a fragment of CaMV gene VI. In fact, in the Podevin and du Jardin study, the authors "found" the gene VI fragments by simply querying a database. A more substantial finding would have been if they found evidence that the gene VI fragments are actually made into functional protein (a prerequisite for the gene VI fragment to cause any deleterious effects), but this study did not investigate this issue. Rather, the study simply looked at what proteins might be produced in the worst case scenario and concluded that any possible proteins made from the gene VI fragments are unlikely to be human allergens or toxins. The authors speculate these possible proteins could be harmful to the plant itself, but because many of these GMOs are very productive plants that produce high yields in commercial settings, this possibility seems unlikely.

Comment Paradigm shifts in Biology (Score 2) 265

Sydney Brenner, who won the Nobel Prize in Physiology or Medicine for his work on programmed cell death, wrote a nice essay in the journal Science (subscription required) describing what he saw as a major paradigm shift in the 1950s and 60s that created modern molecular biology. Prior to the discovery of the structure of DNA by Watson and Crick, biologists had been focusing on how DNA and its associated proteins might be carrying out the functions of the cell. The discovery of the structure of DNA, however, fundamentally changed how researchers approached these questions by revealing that DNA is really just carrying information. Brenner writes:

"We can now see exactly what constituted the new paradigm in the life sciences: It was the introduction of the idea of information and its physical embodiment in DNA sequences of four different bases. Thus, although the components of DNA are simple chemicals, the complexity that can be generated by different sequences is enormous. In 1953, biochemists were preoccupied only with questions of matter and energy, but now they had to add information. In the study of protein synthesis, most biochemists were concerned with the source of energy for the synthesis of the peptide bond; a few wrote about the “patternization” problem. For molecular biologists, the problem was how one sequence of four nucleotides encoded another sequence of 20 amino acids."

Indeed, following this paradigm shift, Watson and others quickly worked out the question of how the information encoded in DNA gets read by the cell and their work now forms the central dogma of modern molecular biology. Therefore, Kuhn's concept of paradigm shifts does indeed apply to biology.

Comment Re:I hope.. (Score 1) 304

William Press and Freeman Dyson recently published a very interesting paper showing that the optimal IPD strategy depends on whether your opponent is mindlessly following a particular algorithm or is actually sentient. In particular, if you who can figure out your opponent's algorithm, you can then game the opponent's algorithm for your benefit. You may find reading the paper (http://www.pnas.org/content/109/26/10409) and the accompanying commentary by Stewart and Plotkin (http://www.pnas.org/content/109/26/10134) to be useful.

Comment Re:I work for one of these companies... (Score 2) 153

You've got it backwards. The cost of materials for sequencing is dropping to $1k, but the data analysis (stitching together all of the short DNA reads to assemble a full genome sequence) still costs well in excess of $1k. For example, a 2011 Chemical and Engineering News article suggests that the cost of the analysis was still ~$100k.

Comment Atomic and Electronic Structure (Score 1) 70

The same group of researchers published a paper in 2009 in the journal Science using a technique called atomic force microscopy (AFM) rather than the scanning tunneling microscopy (STM) approached used here. This technique allowed them to resolve the atomic structure of pentacene, showing the classic ring structure as one might see drawn on a chalk board in their chemistry class. Combined with their means of imaging molecular orbitals by STM, these researchers have developed some really nice tools for studying molecules. Here's the citation for the AFM paper:

Gross et al. (2009) The Chemical Structure of a Molecule Resolved by Atomic Force Microscopy. Science, 325: 1110. doi:10.1126/science.1176210

Comment Re:I'm a little uneasy about this (Score 2) 149

Well, let's say these engineered worms escape into the environment. 1) the paper does not show whether the changes they made to the worm's genome are heritable, so the worm's offspring might not be able to incorporate the unnatural amino acids and the trait might go away after the escaped engineered worms die. Even if the trait is heritable, the paper suggests that the gene cassette they engineered into the worm gets lost from the genome over time, so after a few generations, the trait would likely be lost. 2) these worms do not have the ability to synthesize the unnatural amino acids on their own. They incorporate the unnatural amino acids into their proteins only when the researchers feed the worms large amounts of the unnatural amino acid. Without a source of unnatural amino acids, they are just slightly broken versions of a normal C. elegans worm.

Does this make you feel any better?

Comment Re:What's with the glowing? (Score 1) 149

In the case of this study, the researchers are tricking the worm to incorporate an unnatural amino acid in the place of a stop codon (TAG to be specific). The researchers created an reporter gene that codes for a red fluorescent protein (mCherry) after a TAG stop codon. If the worm is not able to incorporate the unnatural amino acid, the cell will stop producing the protein once it encounters the TAG stop codon and not produce the red fluorescent part of the reporter gene. Successful incorporation of the unnatural amino acid, however, allows the cell to bypass the TAG stop codon and produce the red fluorescent part of the reporter gene. So, even though the unnatural amino acid is not directly producing the fluorescence, seeing the worms glowing red means that the worm's cells were able to incorporate the unnatural amino acid successfully.

Comment Re:Smallpox Genome is Public, Its a Permanent Thre (Score 1) 248

You actually wouldn't need to even start with Vaccinia virus. In 2008, scientists at the J Craig Venter Institute synthesized and assembled the genome of an entire bacterium from scratch (Gibson et al. 2008. Complete Chemical Synthesis, Assembly, and Cloning of a Mycoplasma genitalium Genome. Science 319: 1215 - 1220. doi:10.1126/science.1151721) . The bacterial genome they synthesized was 580,000 base pairs compared to the 186,000 base pair size of the smallpox genome. Of course, commercial gene synthesis companies would never sell anyone any sequence resembling a smallpox sequence, but given enough resources, a government or even some well funded group could conceivably resurrect smallpox without needing a sample of the virus.

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