Mar 28 2014

Synthetic Yeast

Synthetic biology is an emerging field with incredible potential. The idea is to build genomes from the ground up. Craig Venter made the first breakthrough in synthetic biology four years ago when his team created the first artificial bacterial genome. Now another team has made similar progress with yeast, which is eukaryotic (meaning the cells keep their DNA in a nucleus).

To be clear, these teams have not made life entirely from scratch, not even the genome. In Venter’s case he started with an existing bacterium, and then recreated its genome with some changes, and inserted it into a bacterium whose DNA had been removed.

In the latest research, the scientists have created one of the yeast’s 16 chromosomes. Again, they did not build it from scratch but started with the wild chromosome and then made significant changes. They therefore have 15 chromosomes to go, but there is no reason they should not get there.

Some argue that this is not really artificial life, and they have a point- but this is just a semantic argument. They have gone beyond inserting or deleting single gene to making massive changes to the genome, or in this case to a single chromosome. At what point something becomes “artificial” is a bit arbitrary.

In any case, the technology is potentially very powerful. The research that has been done so far is an important proof of concept. What the latest study shows is that a significantly altered chromosome can be added to a yeast cell and the yeast will survive and even reproduce. The new chromosome seems to work fine.

One significant aspect of the changes they made is this:

The new chromosome, known as SynIII, involved designing and creating 273,871 base pairs of DNA – fewer than the 316,667 pairs in the original chromosome.

The researchers removed huge chunks of DNA that they deemed “junk.” There is somewhat of a controversy over whether or not junk DNA (DNA that does not code for proteins or serve a known regulatory function) is truly inactive or unnecessary, or if it simply has unknown regulatory functions. ┬áThe ultimate test of this question is to remove apparent junk DNA and see what happens. If this early experience with yeast holds true in later research, it would strongly suggest that junk DNA is truly junk.

The obvious practical application of this technology once it sufficiently develops is bioengineering life forms to perform industrial tasks. Yeast is a good target because it is used in many industries already (brewing and baking). Yeast species could theoretically be engineered to manufacture medicines and vaccines, biofuels, plastics, and other material.

Cells are living factories, and they can potentially be harnessed for mass production.

Of course, all revolutionary technology will create some anxiety. In a 2012 survey one third of Americans indicated that they felt synthetic life should be banned until it is better understood. Surveys are tricky, but at least it indicates there is some anxiety out there about synthetic life.

Any new technology with the potential for great benefits is likely to also have the potential for abuse and great harm. This technology can be used to create biological weapons, for example. There is also the issue of unintended consequences.

None of this, in my opinion, is a reason not to move forward. Partly we can just let the science sort itself out. If regulations are needed to reduce the risk of abuse or accident, that does not seem like an extreme challenge.

We are likely still years away from practical applications of this technology, but it seems to be moving forward nicely.

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