Artificial DNA
<p><b>Artificial gene synthesis</b> is a method in synthetic biology that is used to create artificial genes in the laboratory. Currently based on solid-phase DNA synthesis, it differs from molecular cloning and polymerase chain reaction (PCR) in that the user does not have to begin with preexisting DNA sequences. Therefore, it is possible to make a completely synthetic double-stranded DNA molecule with no apparent limits on either nucleotide sequence or size.
 
<b>X and Y, meet A, T, C and G</b>
In nature, DNA base molecules, designated A, T, C, and G, pair up. A pairs with T and C with G, forming what looks like steps in a winding staircase — the double helix that is the DNA molecule. Bases determine what amino acids a particular strand of DNA codes for, and therefore what proteins (long strings of amino acids) are produced.
So far, the synthetic bases, which Romesberg's team call X and Y, do not code for any amino acids, the scientists reported. But in principle they — or other synthetic bases — could.
Much as adding a 27th and 28th letter to the English alphabet would allow more words to be created, so adding X and Y to the natural DNA bases would allow new amino acids and proteins to be created. Unknown at this early stage is whether the new proteins would be functional or effectively useless.
Believing that they will be useful, Romesberg co-founded a biotechnology company named Synthorx, which was officially launched on Wednesday. Based in San Diego, Calif., it will focus on using synthetic biology "to improve the discovery and development of new medicines, diagnostics and vaccines," the company said in a statement.
Synthorx has the exclusive rights to the synthetic DNA advance.
 
Floyd Romesberg of the Scripps Research Institute in La Jolla, Calif., and colleagues expanded the genetic language using a pair of synthetic nucleotides, called d5SICS and dNaM, which together make up a new rung of DNA.
The researchers engineered DNA in Escherichia coli bacteriato contain the unnatural bases and process them like normal DNA. They also equipped the bacteria with molecular machinery from algae to import fresh supplies of the foreign nucleotides for DNA copying and repair.
 
<b>Mycoplasma laboratorium</b> is a planned partially synthetic species of bacterium derived from the genome of Mycoplasma genitalium. This effort in synthetic biology is being undertaken at the J. Craig Venter Institute by a team of approximately 20 scientists headed by Nobel laureate Hamilton Smith, and including DNA researcher Craig Venter and microbiologist Clyde A. Hutchison III. Mycoplasma genitalium was chosen as it was the species with the smallest number of genes known at that time.</p>