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Re: BT Natural vs. GMO toxin release



Regarding differences between Bt sprays and modified crops it is worth
adding a bit to what Ann said earlier. The decision documents on Bt in
crops by EPA along with the patents on the genes  show that the DNA
codes for the toxin proteins are changed a great deal. A large Chunk of
the protein is left out of the  modified gene used in  the crop and the
remaining DNA code is altered to make the gene more active in plants and
amino acids  are changed or deleted to make the toxin more active in
plants. The toxin genes are synthetic "improvements"  of the bacterial
toxin. Finally, EPA agrees that since  it would be expensive to purify
toxin from crops to test mammalian and environmental toxicity it was OK
for the companies to safety test using the natural toxin ,  using the
toxin produced in the bacteria (which is different from the protein
produced in the plant).  I think EPA agreed to a "shell game". What I am
saying is that the real plant toxin was never tested! sincerely, joe

Mike Miller wrote:

FYI  MM  from http://www.biotech-info.net/sprays.html

"Differences between Bt-Transgenic Corn Varieties and Conventional Bt
Sprays"


Commentary
E. Ann Clark
SANET post
January 12, 2000

GE-Bt is not the same as conventional soil microbe Bt. The key differences
include:

a) GE-Bt is formed in each plant pesticidal cell as an active endotoxin. It
exists in that form in each cell through its lifespan and enters the soil in
that form when the plant dies. Soil microbe Bt exists in each microbe as an
*inactive* precurser which becomes activated only under very specialized
circumstances in the gut of particular organisms.

b) original Bt is rapidly broken down by UV etc. when applied as a foliar
spray. GE-Bt, once it is in the soil, retains insecticidal activity for at
least 6 months, according to a series of articles from the lab of Stotzky at
NY University (e.g. Tapp, H. and G. Stotzky. 1998. Persistence of the
insecticidal toxin from Bt subsp. Kurstaki in soil. Soil Biol. Biochem.
30:471-476). It is true that GE-Bt is a substrate for microbial degradation
and does decay in the soil, but consider the issue of scale (see below).

c) It was this lab that showed in a recent article (Saxena, D., S. Flores,
and G. Stotzky. 1999. Insecticidal toxin in root exudates from Bt corn.
Nature 402:480) another key difference between original and GE Bt. GE Bt
plants actively exude active endotoxin during their lifetime, so the
insecticidal properties of GE Bt need not wait until plant death to exert
their effects, if any, on soil biota.

d) Other studies showing an effect of other transgenic plants (not Bt) on
soil biota include the following: Donegan, K.K., R.J. Seidler, V.J. Fieland,
D.L. Schaller, C.J. Palm, L.M. Ganio, D.M. Cardwell, and Y. Steinberger.
1997. Decomposition of genetically engineered tobacco under field conditions:
persistence of proteinase inhibitor I product and effects on soil microbial
respiration and protozoa, nematode and microarthropod populations. J. Applied
Ecology 34:767-777.

Doyle, J.D., G. Stotzky, G. McClung, and C.W. Hendricks. 1995. Effects of
genetically engineered microorganisms on microbial populations and processes
in natural habitats. Adv. Appl. Micro. 40.

Giovanni, G.D., L.S. Watrud, R.J. Seidler, and F. Widmer. 1999. Comparison of
parental and transgenic alfalfa rhizosphere bacterial communities using
biolog GN metabolic fingerprinting and Enterobacterial Repetitive Intergenic
Consensus Sequence -PRC (ERIC-PCR). Microb. Ecol. 37:129-139.

e) Not only does GE Bt expose humans, fed livestock, soil biota, and
everything else to a completely unprecedented endotoxin (e.g. active, not the
precursor), but it also does so on an inconceivably larger scale - every cell
of every plant on tens of millions of hectares every year.

This is not the same as soil microbe Bt, not by a long shot

** NOTICE: In accordance with Title 17 U.S.C. Section 107, this material is
distributed for research and educational purposes only. **

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