In the latest meeting of the Year 11 Colloquium, biology teacher Dr Henry Nicholls gave the scholars an overview of one the hottest topics in biology at present: synthetic biology.
Over the last 25 years, DNA sequencing has advanced at such a pace that humans have now described – base by base – the genomes of thousands of different species. Some 20 years ago, for instance, scientists had assembled a draft of the human genome, a 3-billion-long sequence of just four chemical bases (represented by the letters A, C, T and G). It was around this point that a few scientists began to think seriously whether it might be possible to invent entire new genomes, taking a string of bases from a computer and bringing them to life.
Dr Nicholls led a discussion with the Colloquium students of several milestones carried out by one of the main pioneers of SynBio, the American biotechnologist and entrepreneur J. Craig Venter. Interested in describing what has become known as “the minimal genome”, the smallest number of genes sufficient for an organism to survive and reproduce, Venter and his colleagues began working with the parasitic bacterium Mycoplasma genitalium, with its reduced genome of 580,070 base pairs containing just 482 protein-coding genes (Fraser et al., 1995). By disrupting these genes one at a time, they subsequently found that the bacterium seemed able to function perfectly well with just 382 of these genes (Glass et al., 2006).
Moving to a related bacterium Mycoplasma mycoides, one with a faster reproductive rate than M. genitalium, the same researchers demonstrated that it was possible to build a genome from the letters on a computer screen and then successfully bring it to life (Gibson et al. 2010). They subsequently reduced the genome of M. mycoides by more than half to a minimal set of just 473 genes and managed to boot it up in a similar fashion (Hutchison et al., 2016). This manmade organism was given the scientific name Mycoplasma laboratorium, but the scientists gave it a nickname too: Synthia.
The Colloquium students anticipated many of the benefits that this technological approach might bring, including manmade microbes to manufacture multivalent vaccines, target cancerous cells, remove CO2 from the atmosphere or synthesise biofuels as a source of renewable energy. But the scholars were also quick to appreciate that synthetic biology could have unintended consequences and a forthcoming session on the discovery of the CRISPR-Cas9 gene editing technology will give the students the opportunity to debate the limits of such powerful biological tools and how these might be implemented.