Contents - Faperta

452 Biotechnological Approaches for Pest Management and Ecological Sustainability
parameters have been observed. Transgenic protein and DNA are degraded in the gut, and
no transgenic protein or DNA has been found in animal-origin products. Cultivation of
transgenic crops for cattle feed may also reduce the use of pesticides and decrease the
contamination of crops with mycotoxins. Higher amounts of a-amylase and protease
inhibitors, lectins, or alkaloids may increase plant resistance to insects, but may also
decrease the nutritional value of grain. Subchronic in vivo experiments as well as comparison
of nutritional equivalence of transgenic and conventional crops should be carried out
to rule out any adverse effects of transgenic crops as feed/forage.
There were no differences in the survival and body weight of broilers reared on mashed
or pelleted diet prepared with Bt transgenic maize and similar diets prepared using control
maize (Brake and Vlachos, 1998). Comparative feeding studies with broilers and layers
in which conventional maize (50% to 78%) or soybean (27%) in feeds was replaced with
transgenic varieties did not show any signifi cant differences in production parameters
(Chesson and Flachowsky, 2003). Comparative growth studies with broiler chicks, particularly
sensitive to any change in nutrient supply or the presence of toxic elements in their
feed, can be used to screen for any unintended adverse consequence of the recombinant
event not detected by compositional analysis. This does, however, depend on whether the
transgenic plant can be matched to the parental line or another suitable control, and its
suitability for inclusion in broiler diets. Plant DNA derived from feed has been detected in
the muscle, liver, spleen, and kidneys of broilers and layers, but not in eggs. However, no
fragments of transgenic DNA or its expressed protein have been found to date in poultry
meat or eggs or in any other animal tissues examined.
DNA Transfer from Transgenic Food to Microorganisms/Humans
Potential Effects on Human Health Resulting from the Use of Viral DNA in Human Food
Two types of plant viral DNA sequences are commonly used in construction of genes
inserted into genetically modifi ed plants. The fi rst includes “promoters,” usually short
sequences of DNA that are required for the expression of all genes. In genetically modifi ed
plants, the inserted gene is often combined with a promoter derived from the caulifl ower
mosaic virus (CaMV35S). The second type of sequence comprises genes that encode the
outer protective coat proteins of viruses, which when expressed in the host plant, interferes
with the infecting viruses and confers resistance. However, to date, no genetically
modifi ed crops using this second type of gene are grown commercially. It has been suggested
that the introduction of viral DNA sequences into genetically modifi ed plants could
produce new viruses through recombination (“gene exchange”), either with the remnants
of viral DNA sequences that are commonly found in the genomes of all species or with
naturally infecting plant and animal viruses. There are, however, natural barriers to this
process (Aaziz and Tepfer, 1999; Worobey and Holmes, 1999). Most importantly, viruses
generally infect a limited range of species, although there are genetic similarities between
some viruses that infect plants and animals, suggesting that they may have jumped
between these kingdoms in their evolutionary past, but such events must be rare.
Plant and animal viruses are quite dissimilar and plant viruses cannot infect animal
cells. There is only one reported case of recombination between a plant and an animal virus
(Gibbs and Weiller, 1999). Humans have eaten virally infected plants for millennia, and