From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Tue Apr 22 2003 - 16:08:54 MDT
On Tue, 22 Apr 2003, Adrian Tymes wrote:
> Out of curiosity, what are all the costs of genetic
> engineering at this time? There is specialized labor,
> of course, but even with widespread competition (as a
> result of widespread training in the techniques), this
> would still be skilled labor by modern standards, and
> thus the cost of labor would still be a factor. But
> what other costs are there, and how could one minimize
> or eliminate them?
One needs a certain amount of specialized machinery.
DNA synthesizers and sequencers & PCR apparatus to
amplify DNA for example -- these range from a few thousand
to hundreds of thousands of dollars. Then one needs very
high quality water purifiers and sterilizers. Finally one
needs the reagents to perform the actual "engineering" --
a small amount of a single restriction enzyme to cut
up a piece of DNA in a specific place may be a few
hundred dollars (and there are hundreds of different
kinds of restriction enzymes that one might need to use).
Then there are the plastic consumables -- tubes or plates
in which to grow you modified organisms.
It isn't cheap.
> Might it not be simpler just to design a virus to do
> this infection, but not replicate (beyond normal
> cell division, et cetera), then flood the body with
> a lot of this virus?
This involves placing the virus in a host which has been
engineered to have the required additional replication
machinery -- not simple (otherwise how do you get a
sufficient number of viruses?). Then there is a nasty
problem that you don't introduce any of the cells that
are capable of replicating the virus.
> One challenge would be how to make sure the
> virus does not needlessly overwrite the edit on a cell
> that has already been modified, or at least that such
> an overwrite would be harmless.
Yes -- this is the "How many copies do you want problem?".
There are some solutions for this in prokaryotic cells
with bacterial viruses but I'm unaware of any that function
within eukaryotic cells. With their much larger size it
might be difficult for the regulatory proteins to diffuse
sufficiently fast to perform the desired function (of
regulating copy number).
I've thought about this for a long time and haven't managed to come up
with a good solution (which is why I suggested delivering single
pre-engineered secondary nuclei [biobots] outside of the body). One can
always screen such cells to make sure you are getting those with the
correct modifications. Inside the body it is much more difficult to make
sure things are going as planned.
Robert
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