- Feb 16, 2009
- Mohawk valley, Oregon
....It's pretty stunning when you just replace the DNA software in the cell and that cell instantly starts reading that new software, starts making a whole different set of proteins, and within a short while all the characteristics of the first species disappear and a new species emerges from this software that controls that cell moving forward.
The comments about Craig Venter being a "provocative and forward thinker" and the need for sufficient 'hype' to keep the wheels of commerce suitably greased go together very well.Well, its a bit overstated.
Ventner's associates have been optimizing, in slow, stepwise fashion, different procedures for assembling small genome-sized DNA molecules, removing DNA from cells, and introducing engineered DNA into the DNA-denuded cells. This is between closely related microbes with very small genomes.
They are a commercial outfit and there is a need to hype each step to keep the wheels of commerce and development greased.
I am an acquaintence of Craig through our work and have worked with some of his associates in the past. He is provocative and forward thinking, but not the only game in town.
More to come in the near future though, and from many labs...
And he replied:Ventner comments about the structure of the particular DNA strain they intend to use being formulated in a large part on a computer. Can you explain how the strains are actually introduced to the cell? Simply put is through electrical stimulation or through chemicals?
The sequence of the synthetic genome is nearly identical to a natural genome (previously determined by sequencing the natural genome). They modified the sequence in silico (that is, by editing it on the computer, just like editing a file in WORD), then directed a DNA synthesizing machine to create sythetic "oligonucleotide" molecules which were subsequently assembled into large sequences by a mixture of in vitro (in the test tube) DNA synthesis and in vivo (in a cell) recombination (this is what my lab does). The final assembled DNA molecules were isolated and introduced into the DNA-denuded host cell of a closely related bacterium via electroporation. In electroporation, a mixture of cells and DNA are placed between two metal plates and an electrical pulse (on the order of thousands of volts at hundreds of ohms discharged from a capacitor in the tens of microfarad range) temporarily opens pores in the cell wall and facilitates movement of the DNA into some of the cells. The mixture is then transferred to a growth medium and the cells are allowed to recover. Subsequently, bacterial clones are grown up on petri plates, the DNA is reisolated, sequenced, and the investigators determine if they succeeded in reprogramming the cell.
Which is pretty cool!!!Each step along the way has been validated in previous publications and represent somewhat standard lab practices writ large. This paper is a proof of principle....the next big step is to make something really different. For example, Craig is hot to do metabolic engineering to create biofuels using oil-producing pathways found in some unicellular algae and related approaches...
As with all emerging technologies, it is important to "learn the banishing spell first"...I've been beating that drum for decades.