Torsten Brinch
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 Posted: Fri Dec 05, 2003 7:50 pm Post subject: Genetic instability in transgenic lines, studies reveal |
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In a recent study on five commercially approved transgenic lines
carried out by two French laboratories, all five transgenic inserts
were found to have rearranged, not just from the construct used in
transformation, but also from the original structure reported by the
company. This was clear evidence that all the lines were genetically
unstable.
Further evidence has come to light since. The Service of Biosafety and
Biotechnology (SBB) of the Scientific Institute of Public Health (IPH)
in Brussels has published on its website
(http://biosafety.ihe.be/TP/ MGC.html)
reports on the molecular characterisation of the genetic map
of six transgenic lines, four of which overlap with those analysed by
the French laboratories: Bt 176 maize (Syngenta), Mon 810 maize
(Monsanto), T25 maize (Bayer CropScience) and GTS 40-3-2 soybean
(Monsanto).
The IPH is a Scientific Institute of the State, linked to the Belgian
Federal Ministry of Social Affairs, Public Health and the Environment.
The Brussels reports are an overview of data presented at a meeting of
the Belgian Biosafety Advisory Council. The data come from different
scientific institutions, the applicants and from published papers. The
reports found evidence of genetic instability similar to those
described in the French study.
However, there are small and large discrepancies when the two sets of
data are compared. In one case, Bt 176, there may even have been a
misreporting or misidentification of the Bt transgene present, which
the company claimed to be crylAb. Comparison with the public database
revealed that the transgene has only 65% homology with the native
crylAb, but 94% homology with crylAc. Bt toxins are potential
allergens and immunogens; crylAc, in particular, was identified as a
potent systemic and mucosal immunogen, as potent as cholera toxin [3].
The studies also revealed a discrepancy in regulatory practice. UK>s
Advisory Committee on Novel Foods and Processes (ACNFP) and the
Belgian authority both appear to have allowed Monsanto to submit new
molecular data on Roundup Ready soybean when independent analysis
revealed its insert had rearranged.
Most of the discrepancies involve the structure of the insert, the
number of insert(s) and locations within the genome; suggesting that
the transgenic lines are not only unstable but also non-uniform.
Consequently, the results of the molecular characterisation could
differ from sample to sample of the same transgenic line. In other
words, the transgenic lines may well not pass the DUS (distinctness,
uniformity and stability) test, which is required by European
legislation.
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