Synthetic Life: Playing God? No, Not Yet.
Issue 31, August 2010
The physical and biological characteristics of nearly all living organisms are largely determined by the genes possessed through inheritance from both parents, though some simple organisms including most bacteria have only a single parent. Genes consist of paired strands of DNA (deoxyribonucleic acid) linked in a coiled double helix and are commonly packaged in structures called chromosomes and located in the nucleus of a cell. Together, they constitute the genome of the individual. Recently, J. Craig Venter (a genome researcher) and his 23 collaborators reported the design, synthesis and assembly of a new subspecies of the bacterium Mycoplasma mycoides. This remarkable achievement, attracting attention worldwide, was the first time an organism had come into being with an artificial genome in place of an inherited one, that is, it was a synthetic life form. In their paper in the May 20th online issue of Sciencexpress, the researchers describe how they created a cell containing a chromosomal genetic system in which the DNA had been chemically synthesized in sequences designed by a computer programme based on published gene sequences of M. mycoides. This cell exhibited the expected observable characteristics (phenotype) and was capable of continuous self-replication.
Does this mean a complete synthetic organism has been created from scratch in the laboratory? Not quite, for the research involved transplanting the artificial genome into a related bacterial cell, Mycoplasma capricolum, from which all its DNA had been removed. Nevertheless, Venter and his colleagues contend they have produced a "synthetic cell". They argue that over time, with cell replication, the protein and other molecules originally present in the recipient cell are replaced by new ones the syntheses of which are directed by the transplanted genome.
The achievement of Venter's team is the culmination of over 50 years research into the nature and function of genes. Their work, in particular, has developed from the use of so called genetic engineering to incorporate a sequence of synthetic DNA into the genome of an organism in order to produce a desired trait. Outside of the laboratory, this recombinant DNA technology has already provided us with practical outcomes of considerable value. It is employed, for example, on a large scale with bacteria and yeasts as recipient hosts for the production of therapeutic medicines. As a consequence, recombinant insulin has now largely replaced animal sourced (bovine and ovine) insulin for use in treating diabetes. Recombinant human growth hormone is used in treating children with short stature caused by a deficiency in production of this hormone. Examples of recombinant vaccines for use in humans are swine flu vaccine, Gardasil (cervical cancer vaccine) and the hepatitis B virus vaccine. Monoclonal antibodies, such as Herceptin, used as agents in treating cancer also involve recombinant DNA in their production. In agriculture, crop plants have been genetically engineered to be resistant to specific pests (cotton, corn) thus reducing the use of pesticides or alternatively, to be resistant to the pesticides themselves (soybeans, corn, canola).
The science used by Venter's team to create their bacterium undoubtedly will be further developed and widely applied. A totally synthetic genome offers the advantage of full control in its design and subsequent expression. Consequently, the potential to create organisms for specific beneficial purposes would be greatly enhanced over that currently available with recombinant DNA technology. Applications aimed at improving human and animal health, food supply, life-style, and the environment could herald a new industrial era.
On the negative side, the future expansion of synthetic genome applications could present with major ethical and moral issues, a point not ignored by Venter and his associates in their paper. The safety issues associated with an organism not found in nature are a major concern. The danger resulting from the release of an artificial organism into the environment is an unknown but the adverse effects could be extremely serious depending on the type of organism. The potential to produce powerful biological weapons for military purposes is another possible application of the technology and even though there is a moratorium on such weapons it cannot be ignored.
Some commentators have questioned if creating artificial life is playing God. The question might not seem relevant at the level of producing synthetic bacteria but what about synthetic higher life forms and ultimately a human being? To achieve the latter so many challenging scientific hurdles would have to be overcome that it can be considered to be more than highly unlikely, in fact virtually impossible. To put it in perspective, Venter's group chose the bacterium M. mycoides as their model because it is a simple self-replicating organism with a known genome of one million base pairs in size contained in a single circular chromosome. In comparison, the haploid human genome (what we receive from each of our parents) has 23 linear chromosomes, is three thousand times greater in size and consists of 20,000 to 25,000 distinct genes. Are we playing God? No, not yet.
The creation of a synthetic genome capable of expressing itself to produce a new artificial life form is an outstanding scientific achievement. The future applications of the technology involved could bring many and as yet unrecognized benefits to us all. Nevertheless, there are associated significant ethical and moral concerns and as this science advances it will need to be overseen and regulated with care and caution.
Gibson, Daniel G., Glass, John I., Lartigue, Carole, et al (including Venter, J. Craig): Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome. Sciencexpress / www.sciencexpress.org / 20 May 2010 / pgs 1-11 / 10.1126/science.1190719
Associate Professor John France PhD, DSc, FAACB is a biochemist, though now retired, with a special interest in reproductive science and an ongoing interest in bioethical issues. He is a member of the Nathaniel Centre Panel of Advisors.