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Re: Stupid Question re Genetics reply to Dale
Reply to Dale
Dale Wilson wrote:
Joe,
If 0.5% of the kernels
are transgenic, then food made from the grain is made from
approximately 0.5% transgenic grain. Right?
I hope that the determination of transgene pollution in food
is not dependent on determinations of the original grain. The reports
I have seen have been based on milled grain and other processed
foods. Depending on grain alone is a bad idea because a lot of
transgene polluted milled or processed food can slip through.
What we are talking about in the above example is how does the
transgene slip through, and how much is expected to do so.
answer: The main point is that the endosperm is a major contributor to
good transgene pollution in corn and oil seeds. I asked you for studies
supporting your belief that embryo is a richer source of transgens than
endosperm. Clearly such studies should have been done to evaluate the
commercialization of transgenic crops and their suitability for
environmental release. However, no such studies are evident. Joe
A percentage is easily measured by transgene relative to a corn
nuclear gene as reference.
Corn cobs are filled with full of kernels, each kernel represents an
independent fertilization so that the cob may have both transgenic
and normal kernels.
The if you start with 0.5% transgenic grains the food may have a
different percentage of transgenic pollution depending on the
endosperm content of the kernels and the conditions determining
endosperm level such as drought, etc.
I was not trying to split hairs on the quantitation. If 0.5% of the
kernels in the grain are transgenic, then the weight percentage of the
transgenic grain might be slightly different (maybe .48 or .52%) for
the reasons you cite.
answer: Your numbers imply that embryo is much richer in transgenes than
endosperm in the seed and that is very unreal. Endosperm is the food
for embryo and it is much larger than embryo. How much larger is one of
the studies that should have been required by APHIS, but ignored for
fear of the answer. Joe
Each transgenic plant will shed pollen effecting fertilization of
normal plants. As I have indicated, the spread of pollen is not
fixed but efected by wind, placement of the transgenic plant in the
field , etc. A few transgenic
plants can pollinate a large number of normal plants.
It is not just the transgenic plants spreading their pollen around.
All the corn plants are spreading their pollen, and what genes end up
in the kernels depends on the luck of the draw. For that reason, the
frequency of a gene among the gametes is a good predictor of the
frequency with which the gene will end up in the progeny. This is the
tried-and-true way of looking at these problems.
The transgenes themselves constitute a
vanishingly tiny fraction of the DNA in the corn plant.
As I pointed out it is really easy to measure the ratio of
transgene to normal corn marker gene. How else could you deal with
processed foods?
I agree, I think the ratio of the transgene to some generic corn marker
sequence is a good way to quantify contamination. But the discussion
is not about test methods, it is about estimating grain (and food)
contamination based on the contamination of the seed.
Answer: You indicated earlier that quatitation by PCR was not possible
for some reason? Quantitation is most reasonable as I described. You
have some problem in this area that is hard to follow.Joe
I disagree that it is safe and reasonable to assume
that embryo to endosperm ratios are fixed, I understand that they are
effected by environmental conditions and as you know endosperm is
food for the embryo. Perhaps you will provide studies showing that
embryo-endosperm ratios are fixed?
I can show that reasonable shifts in endosperm/embryo ratio will have a
small effect.
answer: But you did not show anything! It is very unwise and
unreasonable to suggest that endosperm is unimportant and invariable in
corn crops. Joe
In conclusion, regulating transgene content in corn by % transgene
polluted kernels is a bad idea because the transgenic plants can
spread a lot of pollen over organic fields causing transgene
pollution of the fields the year the polluted seeds were planted.
Again, you have not provided any reason to believe that one would (or
could possibly) encounter a large change in gene frequency without
doing some sort of intentional selection (like Percy Smeiser did)
answer: It is simply true that corn can spread its pollen a good
distance depending on spatial and weather considerations. It is not
reasonable to presume that corn pollen will spread in a homogenious
pattern pleasing to the chemical companies that patent the corn. Joe
Hope I have cleared up your concerns.
Well, to be honest Joe, I really don't understand what you are getting
at in this thread. I am not trying to spin this, or blow smoke on it.
I just don't understand your argument.
answer; I am happy that you admit that you do not follow the arguments
and the genetics. Now it is time to cough up the data and publications
that you have claimed support your view on the inconsequential
endosperm or just move on to another area of your views and teachings.
Sincerely, Joe
Sincerely,
Dale
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