A number of years ago I rebuilt a carburetor on an old car simply because I wanted to see if I could do it.  I bought a “carb rebuild” kit and tackled the job over a Christmas break.  When I disassembled the old carb I had never seen such a complicated mass of floats, valves, springs, gaskets and screws all integrated for the purpose of feeding just the right mixture of fuel and air into the combustion chambers.  As a biologist, I marveled at the engineering and reveled in the idea that by carefully following directions I could build or create a whole new carburetor.  My Christmas rebuild project didn’t work out so well, and the car never did run right. But the idea that a skilled mechanic could create a new and very complicated machine by replacing critical  parts with new ones, hung in my mind.

When I recently read of Craig Venter and Daniel Gibson’s creation of the first synthetic cell, I couldn’t help but draw a crude and overly-simplified comparison to my Christmas carburetor project.  Obviously these highly acclaimed scientists did more than simply replace a few existing parts and their accomplishment is sure to have lasting beneficial impacts within the fields of medicine, agriculture, pharmaceuticals and environmental remediation in the years and decades to come.  They did indeed create a “synthetic” cell, but did they create a whole new life?

It is very important to note that the Venter team created a synthetic genome from scratch, not a new life from scratch.  There is significant difference between the two.  The true building blocks of all living things are the four nucleotides (adenine (a), cytosine (c), guanine (g) and thymine (t)) that anchor the rungs on the latter of DNA.  The alignment of these four constituents paired across the double helical axis of DNA forms the “genome” specific to each organism on earth.  What Venter and his team did was decipher the genome of a simple bacterium (Mycoplasma mycoides) with a genome length of slightly over 1 million nucleotide pairs.  The genomic alignment was then digitized and stored on a hard drive.  For the first time in history this groundbreaking scientific team then chemically synthesized each nucleotide and aligned them in accordance with the known M. mycoides genome configuration.  There was some modification to the original mycoides genome for identification purposes and the researchers attached overlapping segments for assembly purposes, but for the most part the new synthetic genome was configured to instruct a host microbe to act and function like a Mycoplasma mycoides.  Therefore, the Venter team effectively synthesized a microbial genome for the first time in history – simply amazing.    But did they create a new life form capable of metabolizing and reproducing from scratch?  No!  In order to re-create the new life form, the synthesized DNA fragments were placed into a pre-existing yeast cell where the yeast recognized overlapping fragments and assembled the nucleotides in the proper order.  The final step in creating a new functioning cell was to then transplant the yeast assembled synthetic genome into the cytoplasm of a related bacterium (Mycoplasma capricolum).   This new bacterium was referred to as a synthetic cell only because it was under the control of a synthesized genome, not because it was synthesized from scratch.   In essence, the 20 man research team created a new chromosome and transplanted it into a new but existing life.  The team basically transformed one cell into another, with the new cell or bacterium named Mycoplasma mycoides JCVI-syn1.0.  This was an extremely complicated process requiring $40 million and more than a decade of intensive work.

The bottom line is that a new organism was not designed and manufactured.  Rather, integral synthetic parts were placed within an existing cell forming a fully functional new bacterium – perhaps comparable to a rebuilt carburetor placed atop an existing engine.  The performance of that engine would be dictated by the “new” carburetor.    Again, I do not mean to downplay the significance of the brilliant work of the Venter team.   Genetic manipulation via synthetic genomes will eventually pave the way to mind boggling treatments for heart disease, neurological disorders, cancers, and a myriad of other diseases plaguing mankind.  Craig Venter and his team have effectively accelerated the promising and burgeoning field of “Synthetic Biology”.

Perhaps someday we will witness the true formation of life from scratch (synthetic), but at this point in time, the magnificent balance and fine tuning required for the formation of original life remains an elusive mystery beyond the capabilities of science.