What it is: The world’s first project to build a whole genome of a eukaryotic organism, based on Saccharomyces cerivisiae, entirely out of bits of DNA stuck together by geneticists in labs. Now, to break that down:
Eukaryotic: Organisms with cells with nuclei. (Prokaryotic) cells without nuclei are limited to bacteria and archaea (which look a lot like bacteria to folk who aren’t microbiologists). Cells with nuclei comprise everything else, from yeast all the way up to us.
Genome: Cell software. A genome alone doesn’t do much for you; it’s like having Microsoft Office without a computer. But plug the genome into the right machine (i.e. a cell with mitochondria and ribosomes and other such equipment) and that machine will follow the genome’s instructions.
Build: Most genomes are duplicates of existing genomes, made when cells reproduce themselves. They evolved on their own. Scientists can alter those existing genomes by applying chemicals that induce mutations in DNA, or by using any one of a variety of techniques* to replace a section of existing DNA with new DNA, or to add a whole new DNA sequence. Geneticists can create those DNA sequences in labs, outside of cells, and stick them together. Assembling small bits of DNA in this fashion is genetics bread and butter. This project, however, involves creating and sticking together a whole yeast genome’s worth of DNA, and then putting it inside a cell and letting it run.
Entirely: Scientists build bits of genetic code out of lab-created DNA all the time. Heck, I’ve done it myself, and (don’t be a prude, now) I even started when I was a teenager**. Building an entire genome is a project multiple orders of magnitude larger than putting together a little chunk of DNA. If routine genetic engineering is writing one really well-crafted sentence, then this is composing the complete works of Shakespeare several times over.
World’s first: Really. No one’s done this before. Back in 2008, a synthetic bacterial genome came out of the Venter Institute (famously part of the team that broke news with the first sequenced the human genome in 2000); in 2010 they convinced that genome to run a bacterial cell. The DNA sequence was based on the genus Mycoplasma, well-known for its diminutive genome, and the finished synthetic genome (shorter than the original) was 582,970 base pairs long. S. cerevisiae is along the lines of 12,157,000 base pairs long. Even without knowing much about base pairs (base pairs are to DNA as alphanumeric characters are to Shakespeare), you can see that this is a much bigger project. Prokaryotic and eukaryotic genomes also differ in many other respects. Those differences are important to constructing the synthetic genome as well as to what it’s good for when it’s done.
Based on: The team isn’t precisely duplicating an existing S. cerivisiae genome. It’s starting there, then making modifications: improving efficiency by eliminating some unnecessary bits, writing in some special features that will make the genome easier to mess around with in future experiments, and including fail-safes to lessen the chance of the lab version surviving in the wild should it accidentally escape without the express permission of both the scientists and society at large. (There’s no plan to let it outside the lab, and it would almost certainly be harmless if it escaped, but being extra-certain-careful doesn’t hurt in experimental microbiology.)
You can find more detail on all of that, in wonderfully user-friendly form, at the Synthetic Yeast 2.0 website.
Why you should care:
- If you care about big human achievements, care about this. It’s a big human achievement.
- If you’re a winemaker, or a brewer of beer or baker of bread, or someone else who collaborates heavily with yeast in your professional life, this genome heralds a change. At some point in the future (how far in the future is anyone’s guess), we may be building yeast custom-designed for their tasks in ways impossible through our current selective breeding or even conventional genetic engineering. We might be looking at more efficient yeast that grow faster, tolerate higher alcohol concentrations before dying, or make alcohol more or less efficiently. Whether we should do such things will mean collective conversation about where we’re going as a people and a planet, but the option will be on the table.
- This genome means learning a lot more about yeast, which is good. Among the main reasons this project exists (in addition to the “climb the mountain because it’s there” rationale, and the “stepping stone to bigger things” rationale, and the “develop new genetic tools” rationale) is to fuel more detailed and extensive yeast experiments. That means more information to help winemakers and other yeast-workers understand what their ferments are doing and, if so inclined, change them.
- If you care about science policy, you’ll find plenty here to pique your interest. Synthetic yeast means looking at new questions about what it means to custom-build whole organisms from scratch, and whether and how those organisms might ever be permitted to take up residence in civil society. An interdisciplinary group at the University of Edinburgh is starting those sorts of conversations.
- This project represents a major collaboration amongst a lot of people around the world, including a non university-associated “Biohacker” group in LA (free-range biologists). More than just a genome will inevitably emerge, and interested non-microbiologists at large will be hearing about it.
*Lots of different ways to do this, all of which beg longer explanations than make sense to include here. For one flashy version with interesting implications, Google “crispr” or check out Nature’s or Science’s coverage directly.
**Some of the folk working on this project are teenagers, incidentally, which would be a good deal niftier if the teenagers in question didn’t constitute a designated class at a New York City private school with notoriously, news-worthily fancy pants in New York City.