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shallowdeep -> RE: Man tells God to beat it. (5/22/2010 2:38:17 AM)
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The work, while very interesting, is definitely not the creation of life. I caught part of an interview with Craig Venter on Charlie Rose tonight in which he agreed with that when answering a question about this point, saying, "I don't think we've created life. We've created a new life form." The episode should eventually be available online.
The actual paper is freely available here as a PDF: Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome. There's also a fluffier version of what the team did here: Synthetic Genome Brings New Life to Bacterium.
If you are curious, while they may not be freely accessible, it also helps to take a look at some of the previous publications by the same team leading up to this, namely:
Genome Transplantation in Bacteria: Changing One Species to Another (2007)
and
Creating Bacterial Strains from Genomes That Have Been Cloned and Engineered in Yeast (2009)
Just to sort of recap what was actually done: The genome of one bacteria, Mycoplasma mycoides, was sequenced. A few minor modifications to the sequence were specified and this altered sequence was then created using a process that starts from just base nucleotides – but relies heavily on living cells to put things together. The eventual result was a "synthetic" genome contained in a chromosome. This synthetic chromosome was then successfully transplanted into living cells from a somewhat different bacteria, Mycoplasma capricolum. Offspring containing only genetic information from the synthetic M. mycoides genome were then isolated. The final result was a colony of viable cells containing only a genome (almost*) perfectly identical to the altered genome they set out to synthesize.
I actually think LadyEllen's analogy of assembling parts versus truly creating something from scratch is fairly valid. This is really about manipulating existing life, not about creating it. The techniques used rely heavily on harnessing existing, living organisms. The base chemicals you start with aren't alive, but the process to create something that can reproduce and replicate the synthetic genome is entirely dependent on already having life. E. coli and then and a yeast, Saccharomyces cerevisiae, are used to splice the synthetic DNA sequence together and construct the chromosome. The final step requires a preexisting, living recipient cell similar to that of the original organism to be provided for the chromosome to "hijack" in a manner not dissimilar from how a virus works.
So, this doesn't really create life… and certainly not in an absence of life. Actually being able to control the output of the entire process is pretty impressive, though. Is it revolutionary? Not particularly. This was more about the perfection of techniques and their application on an unprecedented scale (1.08 Mb) than something truly new. It's not something that took anyone by surprise. It's actually almost mildly surprising it took them as long as it did for this latest step. In an interview with CNN Venter noted, "This, when it finally worked, we were more relieved than excited." Is it a breakthrough? Arguably, although major milestone might be a better description.
Whether or not it could be worth a Nobel Prize probably depends on what happens with it. At present, it's not entirely clear how practical the technique will be. This NYT article, for instance, has some quotes that question the value versus more traditional insertion and deletion methods.
That said, the technique is interesting because it may offer a potentially unprecedented level of control in genetic engineering. There are some limitations but, within those, this makes it possible to choose completely arbitrary alterations to a genome and then create a cell with only the new, human-specified, synthetic genome. If that can be coupled with a minimal genome (and, incidentally, this demonstration was not a direct continuation of the efforts towards with Mycoplasma genitalium - although that's doubtless a next step on their agenda) it would make it much easier to figure out what effect various changes to a genome were having and would limit unforeseen interactions with genes not of interest that tend to crop up when making genetic modifications. Potentially, this could be a significantly faster, better way to do some things. It could also turn out to be mostly a dead end in practice.
*One E. coli transposon managed to find its way in, along with a handful of single base mutations.
quote:
ORIGINAL: DomKen
They killed a cell, by removing all of its nuclear DNA. Then they inserted entirely synthetic DNA, sequence based on an existing strain of bacteria but not drawn from that source, into the dead cell. The cell started functioning again...
Just to clarify a bit, that's not how they actually achieved the genome transplantation. The recipient cells absolutely must be alive, and were even still in possession of their original DNA (bacteria don't actually have a nucleus you can remove à la egg enucleation used when cloning much larger eukaryotes). The trick was to include a tetracycline resistance gene in the synthetic M. mycoides genome. They then stressed the M. capricolum cells, which tends to cause bacteria to take up DNA that happens to be floating around near them - in this case the synthetic chromosomes. The synthetic DNA is similar enough that the cell happily treats it as its own (or at least it did once they identified and deactivated a restriction enzyme that sliced their initial attempt to pieces). With two copies of a chromosome, the cell divides, usually sending one copy to each daughter. Placing the progeny in a tetracycline laced medium later kills off all the cells that lack the synthetic version of the chromosome with its tetracycline resistance, leaving only organisms with the synthetic genome.
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