3.1.3 Highly specialised reports on the detection of GMOs in food
unavailable in databases
This section concerns articles or methods mentioned in special
reports (e.g. reports commissioned by national authorities), annual
reports from food research institutes, petition documents from
companies or information presented as posters at conferences.
References to these works cannot be easily found by literature
searches in commonly available databases; dissemination of these
references occurs mainly through personal communications.
Specialised reports of this nature have described detection methods
for genetic elements used in the generation of transgenic corn
(Waiblinger et al., 1997; Pietsch and Waiblinger, 1996; Pietsch
et al., 1997; PGS-petition, 1995), cotton (DuPont-petition), potato
(Pietsch et al., 1997; Waiblinger et al., 1997), sugar beet (Pietsch
et al., 1997; Waiblinger et al., 1997), soybean (Pietsch et al.,
1997; Waiblinger et al., 1997; Wurz and Willmund, 1997), tobacco
(Kriete et al., 1996) and tomato (Pietsch et al., 1997; Waiblinger
et al., 1997; Pietsch and Waiblinger, 1996; Zeneca-petition, 1994).
Almost all of these methods were PCR-based and were applied to
approved genetically engineered products or to genetic elements
that have been frequently used for the generation of the approved
transgenic plants (Pietsch et al., 1997; Waiblinger et al., 1997).
Experimental details such as primer sequences, amplicon length
and cycling parameter are summarised in
Primer sequences and amplicon length in PCR-assays to detect GMOs.
An identification procedure for tomato paste manufactured from
genetically engineered tomatoes from Zeneca and sold in the UK
in 1996 has been reported (press release No. 057/29.5.96 of the
University of Bremen, Germany). The method is based on PCR amplification
of a 506 basepair fragment from the nptII gene (personal communication
G. Meyer, Hanse Analytik, Bremen). That a DNA fragment of this
size could be successfully amplified from a heat-treated sample
with low pH (approximately pH 3) may be surprising at first glance.
Other sources, however, have also reported that DNA has been amplified
from similar samples, even when the length of the chosen amplicons
was considerably shorter, using 137 basepair (Personal communication
H.U. Waiblinger, Chemische Landesuntersuchungsanstalt, Freiburg;
Allmann et al., 1993) and 226 basepair fragments (Ford et al.,
1996; Barallon et al., 1996).
There have also been reports of attempts to identify artificially-introduced
DNA in bread (Annual Report BFE, 1995). In a model detection system,
flour from rye was spiked with E. coli cells or DNA, containing
a phytase gene. E. coli DNA could neither be detected in
fermented dough nor in the final bread product. When large quantities
of bacterial cells (more than 1010 cfu/g) were added, the presence
of foreign DNA was detectable. Such quantities, however, were
considered to be highly unlikely for 'realistic' applications.
Whereas no commercial approval of any cereal variety exists at
present, a genetically modified bakers' yeast developed for bread
making has been approved in the UK, although it is reputedly not
Several publications have focused on the detection of DNA derived
from decomposing transgenic plant material in the soil. The PCR
systems described were specific for genetic elements that had
been introduced in genetically engineered corn (synthetic pat
gene) and rapeseed (pat, P-35S) (Ernst et al., 1996; Feldmann
et al., 1996; Kirchhof et al., 1996), or derived from the so-called
'Changins-potato' (PVY-cp, nptII) field tested in Switzerland
(Stax et al., 1994). In addition, the primers used for the detection
of the nptII gene in soil bacteria or other environmental sources
using genuine (Smalla et al., 1993) or nested PCR (Tsushima et
al., 1995) may also be applicable for the detection of this frequently
used transgene in foods.