Agriculture Reference
In-Depth Information
9 The Fate of Transgenic DNA and
Newly Expressed Proteins
Ralf Einspanier*
Freie Universität Berlin, Institute of Veterinary Biochemistry, Berlin,
Germany
Besides monitoring growth and physiological
performance, the fate of specii c recombinant
biopolymers (recDNA/recProtein) is
frequently used to determine possible
contamination of animal-derived secondary
products like meat, milk and eggs with
transgenes (Beever et al ., 2003). Earlier, a
general transfer of fragmented feed DNA
was detected in selected domestic animal
species (Einspanier and Flachowsky, 2009),
leading to the assumption that an uptake of
feed DNA might rel ect a natural process
potentially useful for GM monitoring in
GM-fed animals.
9.1 Introduction
Knowledge of the fate of ingested
commercialized genetically modii ed (GM)
feed is a major scope of recent research
projects. Concerning the widespread distri-
bution of a growing number of dif erent GM
forage plants, the vast amount of such crops
is nowadays fed to animals. When tracking
the fate of such GM forage and its transgenic
components, the specii c focus is laid on
traceable transgenic biopolymers like DNA
and proteins newly present in the genetically
engineered plants. Current detection tech-
nologies enable a very ef ective analysis of
DNA traces, whereas the presence of newly
expressed proteins is, due to degradation,
not so easy detectable, even after ingestion.
Dif erent mandatory rules deal with the risk
assessment of such new biotech materials,
resulting in distinct regulations; for example,
for the European Union (EC Regulation No
1829/2003). Very often, 90-day rodent
feeding studies are mandatory and have
been widely introduced as one component of
risk assessment concerning consumer safety
before market release of such GM products,
mainly based on an OECD regulation (OECD,
1998). As another alternative, feeding
experiments using farm animals have been
introduced to calculate possible direct
ef ects on domestic animal species like
cattle, pigs or poultry (Phipps et al ., 2006;
see Chapters 5 and 6). However, long-term
feeding studies extending 14 weeks have
seldom been performed (see Chapter 8).
9.2 General Aspects of GM Feed,
Transgenic DNA and Newly
Expressed Proteins
Modern biotechnology enables plant breeders
to introduce foreign genes (recDNA) and
corresponding newly expressed recombinant
proteins (recProtein) of interest into crop
plants, generating novel traits with newly
wanted characteristics (see Chapter 2). h e
i rst generation of GM crop plants was
constructed with emphasis on herbicide
tolerance and insect resistance. Global
production of such GM plants has increased
signii cantly during the last 10 years. As
reported in 2012, a total area of
approximately 170 million hectares (Mha)
of GM plants has been planted in more than
25 countries worldwide (ISAAA, 2013).
Accordingly, the total GM crop area increased
 
 
 
 
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