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[SANET-MG] Bt toxin uncowed to the end



The article below shows some of the complications in the real word of Bt
toxins. To begin with, for transgenic maize event Bt176 different
transgene products sized 36, 40, and 60 kDa have been reported,
indicating that in-plant metabolic processing is occurring or that
multiple products are being produced at the gene.That effect may show
one of the "little secrets" about Bt maize. In the experiments below the
 corn was prepared as ensilage, a way of fermenting the corn so it is
more palatable to the cows (ensilage or silage is described below after
the abstract). The fermented corn degrades both carbohydrates and
protein. It is rather surprising that pieces of the Bt toxin survive the
ensilage and passage through the cow to its manure. Many Bt fragments
may accumulate in soil and groundwater. The worrisome aspect is that
once the Bt toxin is fragmented it is ignored even though the toxin
fragments may very well be active against invertebrates such as
earthworms and for that matter against vertebrates including birds and
mammals. It is very unwise to let the toxin fragments go untested.

Degradation of Cry1Ab Protein from Genetically Modified Maize in the
Bovine Gastrointestinal Tract
Bodo Lutz, Steffi Wiedemann, Ralf Einspanier, Johann Mayer,# and
Christiane Albrecht*

Physiology Weihenstephan, Technical University Munich, Weihenstephaner
Berg 3, D-85350 Freising, Germany; Institute of Veterinary Biochemistry,
Free University of Berlin, Oertzenweg 19b, D-14163 Berlin, Germany; and
Bavarian State Research Center for Agriculture, Prof.-Dürrwaechter-Platz
1, D-85586 Poing, Germany
Abstract:
Immunoblotting assays using commercial antibodies were established to
investigate the unexpected persistence of the immunoactive Cry1Ab
protein in the bovine gastrointestinal tract (GIT) previously suggested
by enzyme-linked immunosorbent assay (ELISA). Samples of two different
feeding experiments in cattle were analyzed with both ELISA and
immunoblotting methods. Whereas results obtained by ELISA suggested that
the concentration of the Cry1Ab protein increased during the GIT
passage, the immunoblotting assays revealed a significant degradation of
the protein in the bovine GIT. Samples showing a positive signal in the
ELISA consisted of fragmented Cry1Ab protein of approximately 17 and 34
kDa size. Two independent sets of gastrointestinal samples revealed the
apparent discrepancy between the results obtained by ELISA and
immunoblotting, suggesting that the antibody used in the ELISA reacts
with fragmented yet immunoactive epitopes of the Cry1Ab protein. It was
concluded that Cry1Ab protein is degraded during digestion in cattle. To
avoid misinterpretation, samples tested positive for Cry1Ab protein by
ELISA should be reassessed by another technique.

The ensilage is described below:
http://edis.ifas.ufl.edu/AG180
Phases of Silage Fermentation
The ensiling process requires several days and can be divided into four
phases. Each of the four phases is characterized by different types of
change in the forage.

    * Phase 1: Plant enzymes and aerobic bacteria metabolize plant
sugars and oxygen trapped in the packed forage, producing carbon
dioxide, water, and heat. The plant tissues continue to live after they
are packed in the silo. This phase progresses until the oxygen is
depleted, usually 24 hours or less after storage. Silage temperature is
elevated 15 to 20°F or more, depending on the amount of air available.

    * Phase 2: When air is depleted, the anaerobic (do not use oxygen)
bacteria ferment plant sugars, producing acetic, lactic, and other
organic acids. This phase may continue for 2 to 4 days; the organic
acids lower silage pH from above 6 to below 5.

    * Phase 3: Once pH is below 4.5, the lactic-acid-producing bacteria
predominate, causing a further reduction in pH. This phase progresses
over 2 to 3 weeks; lactic-acid fermentation slows or stops when the
ferment able sugars are depleted or the low pH inhibits bacterial
growth. For forages with sugar concentrations below 8% of the dry matter
(Table 1 ), this phase is limited because ferment able sugars are not
available.

    * Phase 4: Silage becomes stable and can remain in good quality for
long periods if air does not penetrate. If silage pH and moisture are
elevated, it is possible that clostridial bacteria (usually inhibited by
low pH or low moisture) may grow, degrading silage quality. Clostridial
bacteria grow without oxygen, degrade sugars, and turn lactic acid to
butyric acid, thus causing the pH to rise. They also break down protein
to amines and other undesirable end products. An insufficient
concentration of lactic acid leads to increased decomposition,
dry-matter loss, and reduced palatability of the silage.

my further comments: In spite of all the abuse immuno reactive peptides
 from Cry 1Ab were fed to the cows and spread through the poor beasts
to their poop. Nobody, not even the Germans seems to think about the
biologic activity of such peptides and nobody seems to have tried to
test for activity of such peptides ot the accumualtion in soil and
groundwater.

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