|Paint-By-Numbers Statue of Liberty|
The dream of creating artificial life - that is to say recreate life from scratch with inanimate starting components - has been the dream of some researchers that want to get at the question of:"What is life?" Of these researchers, Craig Venter probably has been the most recognized figure. Craig Venter claims that understanding how one can create life from scratch will also give us the ability to create purpose-driven life-forms. With the current oil spill an example comes to mind where one could create much better bacteria from scratch that would digest oil leaking from the ocean floor. But there are many other possible uses - both positive and potentially detrimental. Regardless, there is quite an intellectual challenge associated with trying to recreate life.
What exactly is needed and what obstacles need to be overcome?
Conceptually, the idea is simple. To make life, one simply should:
- Make DNA.
- Insert DNA into a "proto" cell - something with a plasma membrane around and other cell machinery. (This in itself is a challenge.)
- Push the start button.
The difference between the previous publication and this one was that in this one, they used their own "test-tube" made DNA. This may seem trivial but in reality there are many challenges associated with this.
- Making DNA: The first challenge is trying to string together 1,000,000 base pairs is not easy because we do not have the technology to do it. The Venter lab tackled this problem by inserting specially designed overlapping fragments of DNA into our baker's yeast and let the yeast cells figure out how to knit these overlapping DNA pieces together.
- Getting DNA into the cell: The second challenge was trying to get the lab-created DNA into the second organism. It turns out that the recipient cell has its own defense mechanisms. DNA recognized as "foreign" gets cut into pieces on sight. So simply inserting freshly created lab DNA lead to failure because the recepient cell recognized the new DNA as foreign. To circumvent this problem, the Venter lab came up with two approaches. In one approach, they disabled the recipient defense mechanisms. Native DNA is distinguished from foreign DNA by the presence or absence of little tags on the DNA. In the second clever approach, Gibbs et. al. disguised the new lab DNA by putting on these tags (metyhl groups) at locations where they are also found in the "native" DNA.
This publication is a culmination of all the technologies developed in their lab in the previous steps. The important things to note are:
- If we draw an analogy to computers, the Venter lab demonstrates that DNA is sort of like the software to run the hardware (the rest of the cell). So by inserting different sorts of softwares, we can make the hardware do different things. In this case we are not just talking about superficial changes, but about an entire change in the operating system.
- Did we create artificial life? Well, not quite just yet. In an analogy, at this point, even if we still can't recreate our life-like artistic painting from scratch, we can at least assemble some of the pre-made components, and if we are given some sort of blueprint, we can now paint by numbers. Despite how belittling this may sound, this is a very significant step towards eventually creating our own paintings.
Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome
Science 21 May 2010:
Vol. 328. no. 5981, pp. 958 - 959