The presence of maize intrinsic and recombinant cry1Ab genes in the gastrointestinal (GI) contents, peripheral blood mononuclear cells (PBMC) and visceral organs of calves fed genetically modified Bt11 maize was examined by PCR in a subchronic 90-day performance study. Samples were collected from 6 Japanese Black/Holstein calves each fed Bt11 or non-Bt maize. DNA fragments of maize zein (Ze1), invertase, chloroplast and cry1Ab were detected inconsistently in the rumen fluid and rectal contents at 5 h and 18 h after feeding throughout the experimental period. The chloroplast DNA fragments of ribulose-1, 5-bisphosphate carboxylase/oxygenase (RUBISCO) and tRNA were detected inconsistently in the PBMC, visceral organs or longissimus muscle, while the cry1Ab gene was never detected in the PBMC or visceral organs. These results suggest that feed derived maize DNA was incompletely degraded in the GI tract, but that fragmented DNA was still detectable in the GI contents as a possible source of transfer into calf tissues. The results also suggest that the recombinant cry1Ab was not transferred into PBMC or tissues of calves fed Bt11 maize.
(Toxico-Pathology Section, Department of Safety Research TEL +81-29- 838-7818)
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