From: Harvey Newstrom (mail@HarveyNewstrom.com)
Date: Wed Jul 24 2002 - 10:17:59 MDT
On Wednesday, July 24, 2002, at 02:49 am, Robert J. Bradbury wrote:
> I don't disagree with the analogy with respect to many structural
> features. Doubling the homeobox genes for a "thorax" region does
> not generally give you two "thorax" regions. However you can add
> "antenna" genes under the control of different regulatory factors
> and get additional antenna to appear in alternate regions of the body
> (at least in Drosophila).
Yes, we have all read those experiments. But beta-carotene production
is not a localized structure that can be duplicated elsewhere in the
body. In other words, there aren't structures that are devoid of
beta-carotene production and storage that can merely be turned on.
Beta-carotene production and storage are already turned on everywhere
within the rice.
> Beta-carotene is generally considered to be a lipid-soluble
> vitamin. So long as you don't saturate the lipids with BC
> at so high a level that you change their physical properties
> you do not have to worry about storage structures.
(I know a little bit about beta-carotene, since it was discussed in the
reference book I wrote. I do have a minor in biochemistry and lab
experience in genetics.)
My point was that if all these structures are already storing
beta-carotene, you would have to come up with a method to make them
store more. Just turning on storage won't work, because it's already
on. Just identifying particular lipid stores for storage won't work,
because they are already identified as such. Just turning on
beta-carotene production won't work, because it is already turned on.
In other words, all of the basic genes to produce beta carotene are
already present. Adding more genes that say produce beta-carotene won't
help. You need to increase the lipid ratio, or make storage more
efficient, or somehow change the way or rate it is stored. Modifying
amounts, rates and methods is much more complicated than just copying a
gene to turn it on. We already achieved that easy suggestion. Now we
are getting to the harder stuff.
> Going back to Harvey's analogy, if the blueprint has multiple
> copies of a bedroom design, you *do* get more bedrooms and
> you do have the capacity to sleep more people. The guests
> (BC precursors) don't particularly care if all the bedrooms look
> the same. They care whether or not they have a bed to sleep in.
Yes, but just photocopying portions of the blueprint won't work. You
have to modify the blueprint to add more bedrooms. You have to add
doorways, and make sure those doorways connect to accessible hallways.
You have to links its electrical wiring and air conditioning to the rest
of the house. You have to make sure you don't overload those
utilitites. You actually have to integrate its function into the house
a little bit. Just cutting and pasting existing structures won't work,
unless they are carefully integrated into a functional design.
My real point here is that it is not as simple and obvious as armchair
geneticists here make it sound. We can't just assume that the producers
of golden rice are idiots and that the answer is obvious to extropians.
There really are difficulties that might take years of research to
overcome. It is too easy to "answer" other people's technical problems
without really knowing anything about the research. That's the real
point I was trying to make.
-- Harvey Newstrom, CISSP <www.HarveyNewstrom.com> Principal Security Consultant <www.Newstaff.com>
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