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[SANET-MG] Bt DNA is all wet
Bt toxin DNA persists in soil and groundwater. The persistence of Bt
DNA in the soil, ground water and the aquatic environment is a grave
concern. It is worth reminding readers that Bt DNA from corn is a
synthetic approximation of bacterial Bt DNA. It is unlikely that the Bt
corn DNA came from anywhere else other than corn.
Ecotoxicology and Environmental Safety
Volume 66, Issue 2 , February 2007, Pages 195-203
Occurrence and persistence of Bacillus thuringiensis (Bt)next term and
transgenic previous termBtnext term corn cry1Ab gene from an previous
termaquatic environmentnext term
M. Douville, F. Gagné, C. Blaise and C. André
Genetically modified corn crops and suspensions of Bacillus
thuringiensis (previous termBt)next term are currently used to control
pest infestations of insects of the Lepidoptera family. For this
purpose, the cry1Ab gene coding for protein ?-endotoxin derived from B.
thuringiensis kurstaki (Btk), which is highly toxic to these insects,
was inserted and expressed in corn. The aims of this study were to
examine the occurrence and persistence of the cry1Ab gene from Btk and
previous termBtnext term corn in previous termaquatic environmentsnext
term near fields where previous termBtnext term corn was cultivated.
First, an optimal DNA preparation and extraction methodology was
developed to allow for quantitative gene analysis by real-time
polymerase chain reaction (qPCR) in various environmental matrices.
Second, surface water and sediment were spiked in vitro with genomic DNA
from previous termBt or Btnext term corn to evaluate the persistence of
cry1Ab genes. Third, soil, sediment, and water samples were collected
before seeding, 2 weeks after pollen release, and after corn harvesting
and mechanical root remixing in soils to assess cry1Ab gene content. DNA
was extracted with sufficient purity (i.e., low absorbance at 230 nm and
absence of PCR-inhibiting substances) from soil, sediment, and surface
water. The cry1Ab gene persisted for more than 21 and 40 days in surface
water and sediment, respectively. The removal of bacteria by filtration
of surface water samples did not significantly increase the half-life of
the transgene, but the levels were fivefold more abundant than those in
unfiltered water at the end of the exposure period. In sediments, the
cry1Ab gene from previous termBtnext term corn was still detected after
40 days in clay- and sand-rich sediments. Field surveys revealed that
the cry1Ab gene from transgenic corn and from naturally occurring
previous termBtnext term was more abundant in the sediment than in the
surface water. The cry1Ab transgene was detected as far away as the
Richelieu and St. Lawrence rivers (82 km downstream from the corn
cultivation plot), suggesting that there were multiple sources of this
gene and/or that it undergoes transport by the water column.
Sediment-associated cry1Ab gene from previous termBtnext term corn
tended to decrease with distance from the previous termBtnext term
cornfield. Sediment concentrations of the cry1Ab gene were significantly
correlated with those of the cry1Ab gene in surface water
(R=0.83;P=0.04). The data indicate that DNA from previous termBtnext
term corn and previous termBtnext term were persistent in previous
termaquatic environmentsnext term and were detected in rivers draining
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