Genetically Modified Food: Its uses, Future Prospects and Safety Assessments
In the context of the GM food regulations crop improvement via transgenic technology is a new stage of introducing novel food which supercedes over the conventional breeding. It was analyzed that worlds hunger, malnutrition problems, environmental pollution and phytoremediation in agriculture are the challenges for scientist as well as governments those can be combated by application of genetic engineering in crops. Genetically modified microbes/plant/animals or GM microbes/plant/animals results from modification in the genetic make-up of microorganisms, plants and animals using recombinant DNA technology to improve the nutritional requirement, disease resistant traits, increased production and medicinal properties. In many instances, these modification processes represent faster, more efficient mechanisms for achieving changes than traditional breeding. However, a wide variety of modifications are possible through genetic manipulation and the potential for the introduction of toxic compounds, unexpected secondary effects and changes in nutritional and toxicological characteristics may give rise to safety concerns about GM crops. Thus, generation of GM food explores new vistas for future food requirement but the assessment of policy regarding environmental risks is also to be concerned.
Received: May 04, 2010;
Accepted: July 18, 2010;
Published: October 21, 2010
Most of the foods we eat today come from plants and animals that have been grown and bred by humans for countless generations, undergoing substantial genetic changes over several thousand years. Traditionally, plants or animals with the most desirable characteristics were chosen for food and for breeding the next generation. The desirable characteristics arose from naturally occurring variations in the genetic make-up of individual plants or animals. Thus, genetic modification in this sense occurs naturally and forms the fundamental basis of evolution and breeding. The term genetically modified food (or GM food) refers to products developed through biotechnology. Since, biotechnology can include numerous processes and applications the term genetically modified is applied only to products that have been genetically engineered. Genetically Modified (GM) foods are food items that have had their DNA changed through genetic engineering. Unlike conventional genetic modification that is carried out through time-tested conventional breeding of plants and animals as combining genes from different organisms is known as recombinant DNA technology and the resulting organism is said to be genetically modified, or genetically engineered or transgenic. The GM products include vaccines, food ingredients, medicines, feeds and fibres. The use of recombinantly produced chymosin in cheese production since the end of the 1980s represents one of the first applications of genetic engineering in the food industry. The Flavr Savr tomato was the first genetically modified product entering commerce that was itself a GMO; it thus brought the consumer into close contact with new plant technology. Since then, at least 42 other genetically engineered agricultural crops have been approved.
It is generally agreed that the application of genetic modification does not
inherently increase or decrease the risk associated with an organism. It is
now three decades since some of those early promises were made and a decade
since Genetically Modified (GM) crops were first grown commercially. But the
only substantial way that biotechnology has contributed to the well-being of
the hungry is through higher incomes from the production of GM cotton (Huang
et al., 2002). Only a small set of countries have extended GM food
crops and most of them in a relatively minor way (James, 2004,
2005). The first generation of Genetically Modified (GM)
crop varieties sought to increase farmer profitability through cost reductions
or higher yields. The next generation of GM food research is focusing also on
breeding for attributes of interest to consumers beginning with golden rice,
(Fig. 1) which has been genetically engineered to contain
a higher level of vitamin A and thereby boost the health of unskilled laborers
in developing countries. Golden rice is a GM variety that may have no farm productivity
attributes but has the potential to improve health significantly in regions
where rice is or could be a dietary staple for poor people through providing
pro-vitamin A. (Paine et al., 2005).
|| Comparison of rice (left), Golden Rice 1 (middle) and Golden
Rice 2 (right) (Paine et al., 2005)
The latter characteristic is the result of golden rice being genetically engineered
to contain a higher level of beta-carotene in the endosperm of the grain (Ye
et al., 2000; Beyer et al., 2002).
Transgenic Bt (Bacillus thuringiensis) rice varieties that are resistant
to rice stem borer and leaf roller were approved for environmental release trials
in 1997 and 1998 (Zhang et al., 1999). Farmers
have successfully resorted to genetically improving their crops through deliberated
plant breeding for thousands of years although its scientific basis was not
established until classical Mendelian genetics were rediscovered in the early
twentieth century (Robinson, 1999; Uzogara,
Crop development thereby becomes a continuous process of introducing novel
traits where transgenic technology is a new stage following and coexisting with
conventional crossbreeding. Assessment policy regarding environmental risks
is thus being based on the product rather than the process (Brill,
Many crop plants that are used to produce food ingredients are now being genetically modified for example soya and maize. Soybeans can be processed to yield many different food ingredients from Soya protein and flour to oil and lecithin used as emulsifiers. Maize can also be processed to yield a variety of ingredients from starch and sugars to oil and flour. Some ingredients derived from crop plants are very highly refined for example sucrose and vegetable oils and these refining processes destroy and remove any genetic material and protein that might be present in the food ingredient. The end product that goes into food is therefore not itself modified and cannot be distinguished from that produced by conventional means. Animals that have been genetically modified to produce pharmaceutical products for use in human therapy do not enter the food chain. No GM animals have so far been approved for food use.
Farmers practices have led to altering the genetic constitution and evolution
of crops. In this sense farmers have been considered to be the first genetic
engineers (Jones, 1994; Prakash, 2001).
B12 manufactured from Rhone-Poulenc has been recently approved for food use
in Switzerland apparently using genetically modified Agrobacterium radiobacter.
Efforts to produce Vitamin B2 (riboflavin) using a recombinant Bacillus subtilis
strain has also been reported (Van Loon et al., 1996).
GENETICALLY MODIFIED FOODS/CROPS
Genetically modified foods originally derived from Agrobacterium tumefaciens is the most frequently used as a terminator in approved transgenic crops (Table 1). Several Biotechnologist and researchers worked on various crops for nutritionally improved traits intended to provide health benefits to consumers with genetically modified foods/crops. They have tried to develop GM crop resistance to certain pesticides and herbicide also e.g., rape seed and soybeans. Genetically modified crop helps in developing male sterile line facilitating production of hybrid cultivars.
IDENTIFICATION OF GENETICALLY MODIFIED FOODS
The ever increasing number of approvals granted spurred strong interest in developing methods for identifying GMOs in food. The availability of suitable identification procedures is necessary also for various food control activities such as the observance of regulations on the labelling on GMOs and of regulations with respect to seed certification. The requirements on the specificity of detection methods will increase significantly with the number of distinct products available the appearance of mixtures of distinct GMO products and increased processing of such products or complex mixtures. The main methods of identification of genetically modified foods are described.
PCR-based methods: This technique has revolutionized molecular biology
and many other areas in the biomedical sciences in the mid 1980s (Saiki
et al., 1985).
|| List of important crops genetically modified with nutritionally
improved traits intended to provide health benefits to consumers and domestic
The number of references to PCR in the scientific literature has been estimated
to be more than 40,000 (White, 1996).
The high chemical and thermal stability of DNA the high sensitivity of the
method, its technical simplicity the vast amount of experience already accumulated
with it; along with the apparent potential for automation (Abramowitz,
1996; White, 1996) are main advantages of this method
establishing the current prevalence of PCR-based detection methods. This preference
is likely to continue in the foreseeable future.
The sensitivity of a PCR test can be significantly improved by increasing the
number of cycles (Meyer et al., 1994). The application
of magnetic capture-hybridization-technique has also been shown to augment the
sensitivity of an assay by two orders of magnitude (Jacobsen,
1995). Using hemi-nested PCRor nested PCR (Brockmann
et al., 1996; Meyer, 1995; Lunel
et al., 1995) instead of conventional PCR represents another way
of increasing assay sensitivity. Sensitivity may be assessed through a positive
control which targets a sequence of similar length expected to be present in
similar quantity as the actual target sequence.
Various nucleotide-based amplification methods and their applicability: Most of the nucleotide-based amplification methods have generally not yet been used widely for the identification of genetically engineered food or food stuffs. Therefore, very much restricts itself to survey review articles that may simplify access to additional readings. Some of the techniques may under certain circumstances be appropriate for food analysis.
Protein-based methods: The application of protein-based detection methods
for the identification of genetically engineered food products is generally
restricted to fresh (or frozen) and unprocessed foods. Protein samples obtained
from GMOs can be resolved with one-dimensional SDS-gel electrophoresis. Unfortunately
the resolution is not sufficient to clearly distinguish the protein pattern
of a GMO from the protein pattern of its conventional counterpart. Two-dimensional
gel electrophoresis provides better resolution but still may generally not be
able to provide unequivocal identification of a transgene product unless combined
with immunological methods. The expression level of transgene products in plants
were reported to constitute 0 to 2% of the total soluble protein even when strong
constitutive promoters were used to drive expression (Longstaff
et al., 1995). Provided that specific antibodies against the proteins
encoded by the transgenes are available one-dimensional (Padgette
et al., 1995; Wood et al., 1995;
Yang et al., 1996) and certainly also two-dimensional
gel electrophoresis, in combination with Western-blot analysis are suitable
detection methods. ELISA can also be an inexpensive but powerful technique (Padgette
et al., 1995; Wood et al., 1995).
Recently, developed techniques using immunosensors have up to now mainly been
used for the analysis of serum and blood samples (Morgan
et al., 1996). All immunological methods described above depend on
the availability of highly specific antibodies. The latter are commercially
available only for a small number of proteins that are the products of transgenes
used in approved genetically engineered crops.
Detection of enzymatic activities: The detection methods based on measuring
enzymatic activities are limited to the detection of transgenes that represent
enzymes. Enzymatic function of a protein depends on the structural preservation
of the protein molecule even more than the recognition of the protein by antibodies.
Therefore an important restriction of enzymatic methods is the requirement that
the sample must be fresh enough to contain enzymatic activity. With this in
mind, it seems highly unlikely that detection of certain enzymatic activities
e.g., by measuring the enzymatic EPSPS activity (Padgette
et al., 1987, 1988) will find broad application
in the detection of genetically engineered food.
A transgenic plant is one that has received a segment of DNA or genes from another organism. The nucleic acid preferably DNA that has been transferred using recombinant DNA techniques is known as heterologous or foreign DNA. The foreign DNA is integrated through natural systems present in plant cells into the plants genome. The newly introduced genes are subsequently inherited in a normal Mendelian manner through pollen and egg cells. The process of introducing DNA into plants is called transformation mainly using the Agrobacterium mediated method and it can be achieved both in monocotyledonous plants such as wheat, barley and rice, in dicotyledonous plants such as soyabean, potato and tomato.
Agrobacterium mediated transformation in plants Agrobacterium tumefaciens
is a soil bacterium that causes crown gall disease on some plants. Many
dicotyledonous species are susceptible to infection by this species. In causing
crown gall disease A. tumefaciens transfers DNA (the transferred DNA
or T-DNA) from the bacterium to the plant. In nature the transferred bacterial
DNA cause the symptoms associated with crown gall disease. In the early 1980s
scientists removed the disease causing genes from this bacterium and the T-DNA
is now routinely used to transport foreign genes into plants. Agrobacterium
cells carrying the foreign genes of interest are incubated with cultured
cells of the recipient crop plant and transgenic plants are regenerated from
them. Not all cells subjected to this process are successfully modified so it
may be necessary to identify the modified cells using marker genes which are
closely linked to the genetic material that is transferred. These selectable
marker genes usually confer resistance to an antibiotic such as kanamycin or
resistance to an herbicide.
In essence genetic modification involves the identification of the gene coding
for a particular desired characteristic and the moving of that gene from one
living thing where it occurs naturally to another living thing in which the
characteristic is required. Recombinant DNA technology DNA sequencing from genes
using DNA markers for constructing genetic maps designing PCR-based methods
for selecting and characterizing genes and DNA transfer technologies between
different species have all laid the foundations for the modern production of
the genetically-engineered plants and crops currently on the market (Conner
and Jacobs, 1999).
The following are the steps for the genetic modification:
||Isolation of DNA
||Transfer and modification of DNA
||Multiplication of the desired gene and insertion into the host cell
||Selectable marker genes
||DNA sequences necessary to control gene expression
||Selection and subsequent propagation
More recent developments in the genetic modification of plants are beginning
to allow the expression of the gene to be targeted to only certain parts of
the plant such as the leaves and roots. This is achieved by careful selection
of the promoter switch. For example genes for pest resistance could be expressed
only in the parts of the plant susceptible to attack by the pest and not in
the parts of the particular plant used for food. A heat-stable form of Aspergillus
fumigatus phytase has also been engineered which can break down the phytate
ingested from other food sources (Prakash, 1997). Moreover
transgenic technology has been useful in producing hypoallergenic crops by interfering
with the expression of genes encoding major allergens (Bhalla
and Singh, 2004; Losada and Fonseca, 2007). A gene
encoding Galanthus nivalis snowdrop lectin (GNA lectin) has been inserted
into a number of different food crops including rice, wheat, potatoes and sugarcane
(Stoger et al., 1999; Setamou
et al., 2002; Poulsen et al., 2007a,
b) to confer resistance to several insect pest species
(Gatehouse et al., 1998).
MERITS OF GENETICALLY MODIFIED FOODS
The GMOs are approved like many crops previously developed using more conventional
plant breeding techniques. The technology does have the potential to produce
foods that could be of direct consumer benefit such as:
||Improved nutritional quality like Fruit and vegetables with
increased vitamin content, non-allergenic peanuts, potatoes with higher
starch content thus resulting in healthier chips, corn with increased essential
fatty acid content, wheat with increased levels of folic acid etc.
||Prolonged shelf life with good quality
Nutritional: Malnutrition is common in third world countries where impoverished
peoples rely on a single crop such as rice for the main staple of their diet.
However, rice does not contain adequate amounts of all necessary nutrients to
prevent malnutrition. If rice could be genetically engineered to contain additional
vitamins and minerals, nutrient deficiencies could be alleviated. For example
blindness due to vitamin A deficiency is a common problem in third world countries.
Researchers at the Swiss Federal Institute of Technology Institute for Plant
Sciences have created a strain of golden rice. Golden Rice a variety
of rice engineered to produce β-carotene (pro-vitamin A) has been further
improved to produce 23 times more total carotenoids than the previous Golden
Rice version produced in 2000 (Paine et al., 2005).
Since, this rice was funded by the Rockefeller Foundation a non-profit organization the Institute hopes to offer the golden rice seed free to any third world country that requests it. Plans were underway to develop golden rice that also has increased iron content.
However, as discussed in more detail elsewhere (Anderson
et al., 2004) second-generation GM varieties such as golden rice
require a treatment different from first-generation GM varieties. Bouis
(2002) and Welch (2002) suggest nutritionally enhanced
rice and wheat cultivars are more resistant to disease their roots extend more
deeply into the soil so they require less irrigation and are more drought resistant
they release chemical compounds that unbind trace elements in the soil and thus
require less chemical inputs and their seeds have higher survival rates.
Another example of directly improving food micronutrients comes from Iron Rice
which is a GM rice having increased iron content obtained by inserting a gene
from the Aspergillus niger fungus into the rice genome (Prakash,
1997; Lucca, 1999).
Genetic engineering has also enabled improving food and feed protein quality
by incorporating genes encoding non-allergenic proteins containing essential
amino acids (De Lumen et al., 1997; Roller
and Hallander, 1998; Chakraborty et al., 2000).
Pharmaceuticals: Medicines and vaccines often are costly to produce and sometimes require special storage conditions not readily available in third world countries. Researchers are working to develop edible vaccines in tomatoes and potatoes. These vaccines will be much easier to ship, store and administer than traditional injectable vaccines.
Pest resistance: Crop losses from insect pests can be staggering resulting in devastating financial loss for farmers and starvation in developing countries. Farmers typically use many tons of chemical pesticides annually. Consumers do not wish to eat food that has been treated with pesticides because of potential health hazards and run-off of agricultural wastes from excessive use of pesticides and fertilizers can poison the water supply and cause harm to the environment. Growing GM foods such as B.t. corn can help eliminate the application of chemical pesticides and reduce the cost of bringing a crop to market.
Phytoremediation: Not all GM plants are grown as crops. Soil and ground water pollution continues to be a problem in all parts of the world. Plants such as poplar trees have been genetically engineered to clean up heavy metal pollution from contaminated soil.
Approach to the assessment of GM foods in comparison with the evaluation of medicines. It has been suggested that the safety of novel and GM foods should be assessed in a similar way to that used for pharmaceutical products. The ACNFP has recently considered this issue and has advised that long term feeding studies should be carried out where it is relevant and appropriate to do so. However, each case needs to be considered on its merits. Complicating factors in the design and interpretation of long term studies when applied to foods as opposed to pure chemicals mean that it is unlikely that they would give rise to meaningful information in all cases.
Pharmaceutical products are generally well characterized materials of known purity of no nutritional value and human exposure levels are normally low. It is relatively straightforward therefore to feed such compounds to animals at a range of doses some orders of magnitude greater than the expected human exposure levels in order to identify any potential adverse effects of importance to humans. In this way it is possible in most cases to determine levels of exposure at which adverse effects are not present and so set safe upper limits by the application of appropriate safety factors.
Herbicide tolerance: For some crops it is not cost-effective to remove weeds by physical means such as tilling so farmers will often spray large quantities of different herbicides (weed-killer) to destroy weeds a time-consuming and expensive process that requires care so that the herbicide doesn't harm the crop plant or the environment. Crop plants genetically engineered to be resistant to one very powerful herbicide could help prevent environmental damage by reducing the amount of herbicides needed. For example Monsanto has created a strain of soybeans genetically modified to be not affected by their herbicide product Roundup. A farmer grows these soybeans which then only require one application of weed-killer instead of multiple applications, reducing production cost and limiting the dangers of agricultural waste run-off..
Disease resistance: There are many viruses, fungi and bacteria that cause plant diseases. Plant biologists are working to create plants with genetically engineered resistance to these diseases.
Cold tolerance: Unexpected frost can destroy sensitive seedlings. An antifreeze gene from cold water fish has been introduced into plants such as tobacco and potato. With this antifreeze gene, these plants are able to tolerate cold temperatures that normally would kill unmodified seedlings.
Drought salinity tolerance: As the world population grows and more land is utilized for housing instead of food production farmers will need to grow crops in locations previously unsuited for plant cultivation. Creating plants that can withstand long periods of drought or high salt content in soil and groundwater will help people to grow crops in formerly inhospitable places.
DEMERITS OF GM FOODS
Environmental hazards: Unintended harm to other organisms a laboratory study was published in Nature showing that pollen from Bt. corn caused high mortality rates in monarch butterfly caterpillars. Monarch caterpillars consume milkweed plants, not corn, but the fear is that if pollen from Bt. corn is blown by the wind onto milkweed plants in neighboring fields the caterpillars could eat the pollen and perish. Reduced effectiveness of pesticides just as some populations of mosquitoes developed resistance to the now banned pesticide DDT many people are concerned that insects will become resistant to B.t. or other crops that have been genetically modified to produce their own pesticides. Gene transfer to non-target species another concern is that crop plants engineered for herbicide tolerance and weeds will cross-breed resulting in the transfer of the herbicide resistance genes from the crops into the weeds. These super weeds would then be herbicide tolerant as well. Other introduced genes may cross over into non modified crops planted next to GM crops. Genes are exchanged between plants via pollen. Two ways to ensure that non-target species will not receive introduced genes from GM plants are to create GM plants that are male sterile (do not produce pollen) or to modify the GM plant so that the pollen does not contain the introduced gene.
Human health risks: Allergenicity has developed life-threatening allergies to peanuts and other foods among the childrens and adults. There is a possibility that introducing a gene into a plant may create a new allergen or cause an allergic reaction in susceptible individuals. Unknown effects on human health is a growing concern that introducing foreign genes into food plants may have an unexpected and negative impact on human health. The most common allergy causing foods are cows milk, eggs, fish, shellfish, tree nuts, wheat, peanuts, and soybeans etc.
Economic concerns: Bringing a GM food to market is a lengthy and costly process and of course agribiotech companies wish to ensure a profitable return on their investment. Many new plant genetic engineering technologies and GM plants have been patented and patent infringement is a big concern of agribusiness. Yet consumer advocates are worried that patenting these new plant varieties will raise the price of seeds so high that small farmers and third world countries will not be able to afford seeds for GM crops thus widening the gap between the wealthy and the poor. Unfortunately Bt. toxins kill many species of insect larvae indiscriminately but it is not possible to design a Bt. toxin that would only kill crop damaging pests and remain harmless to all other insects.
The fears of the people opposing the technology producing GM crops are associated
with a wider spectrum of issues includes that the companies are more interested
in increasing their profits than in protecting the environment or alleviating
hunger the possibility that transgenic crops may invade wild ecosystems with
detrimental effects on biodiversity the unfair competition with other agricultural
systems such as organic agro-ecological and traditional ones the negative effects
that GM food might produce on human health the possible negative impact of GM
crops on food supply safety. The concern that risk-averse poor farmers would
be unable to afford to take up the higher cost of GM seeds provided by private
biotech firms does not seem to be vindicated by the dramatic take-up of GM cotton
in developing countries as soon as it is available and can be seen to be profitable.
On the adoption experience in China and India (Pray et
al., 2003) the part of the reason for that rapid uptake in developing
countries may be because of the occupational health benefits for farmers who
expose themselves to fewer chemical pesticides with GM cotton (Hossain
et al., 2004) but mainly it is because of its much greater productivity.
SAFETY ASSESSMENTS TESTS USED FOR GM FOODS
The safety assessment of GM food relies of substantially equivalent to conventional
foods when levels of nutrients, allergens, or naturally occurring toxins are
not substantially different and there no new allergens or toxins detected. The
approach to assessing the safety of genetically engineered food products is
to focus on the gene product and its function including the product produced
as a result of its function. This includes chemical analysis and evaluation
of nutritional composition for proteins, amino acid profiles, fat, carbohydrates,
fiber, vitamins and minerals, digestibility tests, toxicity studies, animal
feeding studies, phenotypic characteristics, molecular characterization, immunotoxicity,
genotoxicity and allergenicity testing. The assessment of the safety of GM organisms
addresses both intentional and unintentional effects that may result as a consequence
of genetic engineering of the food source. Future transgenic crops are expected
to contain fewer or no marker genes in the final products since marker free
insertion techniques or methods to eliminate marker genes from transgenic plants.
The assessment of safety measures are a lengthy and tedious process (Fig.
2, 3). The nutritional aspects, risk characterization
and exposure assessment are preliminary steps being taken. Before hitting the
market, all GM products have to pass all the allergic tests and provide the
details. Only those products find as possessing no harmful or allergic effects
are only recommended.
A number of studies over the past decade have revealed that genetically engineered
foods can pose serious risks to humans, domesticated animals, wildlife and the
environment. Human health effects can include higher risks of toxicity, allergenicity,
antibiotic resistance, immune-suppression and cancer.
||Assessment of the allergenic potential of foods derived from
genetically modified crop plants
As for environmental impacts the use of genetic engineering in agriculture
could lead to uncontrolled biological pollution threatening numerous microbial
plant and animal species with extinction and the potential contamination of
non-genetically engineered life forms with novel and possibly hazardous genetic
material. Despite the potential of this achievement as a viable and sustainable
alternative contributing towards alleviating Vitamin A deficiency in many poor
countries (Mayer, 2007) anti biotech opponents have
claimed that Golden Rice is not effective and superfluous (Greenpeace,
Some Golden Rice critics argue that this GM crop might actually interfere with
current vitamin A supplement and fortification programmes (Mayer,
2005). However, opponents of GM technology often ignore the great number
of people who are not receiving the benefits of these programmes.
Known food allergens known toxins and nutritional quality can all be evaluated
in a straight forward manner employing well established in vitro analytical
methods. All three testing strategies use the same procedures for this purpose.
Assessing unanticipated allergens and toxins is more challenging. It is in this
area that the three testing strategies described below differ. These strategies
employ various combinations of the following three approaches to detecting and
characterizing allergens and toxins:
||In vivo testing using small animals and human subjects
for the purpose of screening broadly for allergens and toxins
||Molecular characterization of the genetic alterations induced through
recombinant DNA modifications
||Controlled and monitored commercial release of recombinant foods
Safety testing of GM foods in laboratory animal species:
Examples of safety studies with GM food and feed are given in (Table
2). In different experiments food and feed derived from GM plants, mixed
in animal diets have been fed to rats or mice during different periods of administration,
and parameters such as body weight, feed consumption, blood chemistry, organ
weights, histopathology, etc., have been measured.
|| Safety studies performed on laboratory animals with GM plant
|(Data collected by Dr. G. A., RIKILT, partly derived from
Kuiper et al., 2003)
Genetically-modified foods have the potential to solve many of the world's hunger and malnutrition problems and to help protect and preserve the environment by increasing yield and reducing reliance upon chemical pesticides and herbicides. Yet there are many challenges ahead for governments especially in the areas of safety testing, regulation, international policy and food labeling. Many people feel that genetic engineering is the inevitable wave of the future and that we cannot afford to ignore a technology that has such enormous potential benefits. It has been estimated that demand placed on world agricultural production by 2050 will double assuming moderately high income growth taken together with expected population growth. However, we must proceed with caution to avoid causing unintended harm to human health and the environment as a result of our enthusiasm for this powerful technology.
Genetic modification has increased production in some crops but the evidence
we have suggests that the technology has so far addressed too few challenges
in few crops of relevance to production systems in many developing countries.
Even in developed countries a lack of perceived benefits for consumers and uncertainty
about their safety have limited their adoption.
1: Abramowitz, S., 1996. Towards inexpensive DNA diagnostics. Trends Biotechnol., 14: 397-401.
2: Losada, O.A. and C.A.G. Fonseca, 2007. Alimentos transgenicosy alergenicidad. Rev. Fac. Med., 55: 251-269.
3: Anderson, K., L.A. Jackson and C.P. Nielsen, 2004. Genetically modified rice adoption Adoption: Implications for welfare and poverty alleviation. Proceedings of the 7th Annual Conference on Global Economic Analysis, June 17-19, Washington DC., pp: 1-24.
4: Barro, F., L. Rooke, F. Bekes, P. Gras and A.S. Tatham et al., 1997. Transformation of wheat with high molecular weight subunit genes results in improved functional properties. Nat. Biotechnol., 15: 1295-1299.
CrossRef | Direct Link |
5: Beyer, P., S. Al-Babili, X. Ye, P. Lucca, P. Schaub, R. Welsch and I. Potrykus, 2002. Golden rice: Introducing the beta-carotene biosynthesis pathway into rice endosperm by genetic engineering to defeat vitamin a deficiency. J. Nutr., 132: 506-510.
PubMed | Direct Link |
6: Bhalla, P.L. and M.B. Singh, 2004. Knocking out expression of plant allergen genes. Methods, 32: 340-345.
7: Bouis, H.E., 2002. Plant breeding: A new tool to fight micronutrient malnutrition. J. Nutr., 132: 491S-494S.
Direct Link |
8: Brake, D.G. and D.P. Evenson, 2004. A generational study of glyphosatetolerant soybeans on mouse fetal, postnatal, pubertal and adult testicular development. Food Chem. Toxicol., 42: 29-36.
Direct Link |
9: Brill, W.J., 1986. The Impact of Biotechnology and the Future of Agriculture. In: Responsible Science: The Impact of Technology on Society, Byrne, K. (Ed.). Harper and Row, New York, pp: 31-48.
10: Brill, W.J., 1985. Safety concerns and genetic engineering in agriculture. Science, 227: 381-384.
11: Brockmann, E., B. Jacobsen, C. Hertel, W. Ludwig and K.H. Schleifer, 1996. Monitoring of genetically modified Lactococcus lactis in gnobiotic and conventional rats by using antibiotic resistance markers and specific probe or primer based methods. Syst. Applied Microbiol., 19: 203-212.
12: Buhr, T., S. Sato, F. Ebrahim, A. Xing and Y. Zhou et al., 2002. Ribozome termination of RNA transcripts downregulate seed fatty acid genes in transgenic soybean. Plant J., 30: 155-163.
13: Chakraborty, S., N. Chakraborty and A. Datta, 2000. Increased nutritive value of transgenic potato by expressing a nonallergenic seed albumin gene from Amaranthus hypochondriacus. Proc. Natl. Acad. Sci., 97: 3724-3729.
Direct Link |
14: Chen, Z., T.E. Young, J. Ling, S.C. Chang and D.R. Gallie, 2003. Increasing vitamin C content of plants through enhanced ascorbate recycling. Proc. Natl. Acad. Sci. USA., 100: 3525-3530.
CrossRef | Direct Link |
15: Chen, Z.L., H. Gu, Y. Li, Y. Su and P. Wu et al., 2003. Safety assessment for genetically modified sweet pepper and tomato. Toxicology, 30: 297-307.
16: Conner, A.J. and J.M. Jacobs, 1999. Genetic engineering of crops as potential source of genetic hazard in the human diet. Mutat. Res., 443: 223-234.
17: Del Vecchio, A.J., 1996. High laurate canola. How calgene`s program began, where it`s headed. [INFORM] International news on fats. Oils Related Mater., 7: 230-243.
18: De Lumen, B.O., D.C. Krenz and M. Jamela, 1997. Molecular strategies to improve the protein quality of legumes. Food Technol., 51: 67-70.
19: Dinkins, R.D, M.S.S. Reddy, C.A. Meurer, B. Yan and H. Trick et al., 2001. Increased sulfur amino acids in soybean plants overexpressing the maize 15 kDa zein protein. In vitro Cell Dev. Biol. Plant, 37: 742-747.
Direct Link |
20: Duvick, J., 2001. Prospects for reducing fumonisin contamination of maize through genetic modification. Environ. Health Perspect, 109: 337-342.
21: El Sanhoty, R., A.A. Abd El-Rahman and K.W. Bogl, 2004. Quality and safety evaluation of genetically modified potatoes Spunta with Cry V gene: compositional analysis, determination of some toxins, antinutrients compounds and feeding study in rats. Nahrung, 48: 13-18.
22: Ewen, S.W.B. and A. Pusztai, 1999. Effect of diet containing genetically modified potatoes expressing Galanthus nivalis lectin on rat small intestine. Lancet, 354: 1353-1354.
23: Fares, N.H. and A.K. El Sayed, 1998. Fine structural changes in the ileum of mice fed on delta-endotoxin-treated potatoes and transgenic potatoes. Nat. Toxins, 6: 219-233.
24: Fraser, P.D., S. Romer, J.W. Kiano, C.A. Shipton and P.B. Mills et al., 2001. Elevation of carotenoids in tomato by genetic manipulation. J. Sci. Food Agric., 81: 822-827.
25: Greenpeace, 2005. Genmanipulierter reis: Nicht wirksam unuberflussig. http://de.einkaufsnetz.org/presse/16102.html?P.
26: Guo, D., F. Chen, J. Wheeler, J. Winder, S. Selman, M. Peterson and R.A. Dixon, 2001. Improvement of in-rumen digestibility of alfalfa forage by genetic manipulation of lignin O-methyltransferases. Transgenic Res., 10: 457-464.
27: Hammond, B., R. Dudek, J. Lemen and M. Nemeth, 2004. Results of a 13 Week safety assurance study with rats fed grain from glyphosatetolerant corn. Food Chem. Toxicol., 42: 1003-1014.
28: Hammond, B., R. Dudek, J. Lemen and M. Nemeth, 2006. Results of a 90-day safety assurance study with rats fed grain from corn borerprotected corn. Food Chem. Toxicol., 44: 1092-1099.
29: Hammond, B., J. Lemen, R. Dudek, D. Ward, C. Jiang, M. Nemeth and J. Burns, 2006. Results of a 90-day safety assurance study with rats fed grain from corn rootworm-protected corn. Food Chem. Toxicol., 44: 147-160.
30: Hashimoto, W., K. Momma, T. Katsube, Y. Ohkawa and T. Ishige et al., 1999. Safety assessment of genetically engineered potatoes with designed soybean glycinin: Compositional analyses of the potato tubers and digestibility of the newly expressed protein in transgenic potatoes. J. Sci. Food Agric., 79: 1607-1612.
Direct Link |
31: Hashimoto, W., K. Momma, H.J. Yoon, S. Ozawa and Y. Ohkawa et al., 1999. Safety assessment of transgenic potatoes with soybean glycinin by feeding studies in rats. Biosci. Biotechnol. Biochem., 63: 1942-1946.
32: Hellwege, E.M., S. Czapla, A. Jahnke, L. Willmitzer and A.G. Heyer, 2000. Transgenic potato (Solanum tuberosum) tubers synthesize the full spectrum of inulin molecules naturally occurring in globe artichoke (Cynara scolymus) roots. Proc. Natl. Acad. Sci., 97: 8699-8704.
CrossRef | Direct Link |
33: Hipskind, J.D. and N.L. Paiva, 2000. Constitutive accumulation of a resveratrol-glucoside in transgenic alfalfa increases resistance to Phoma medicaginis. Mol. Plant-Microbe Interact., 13: 551-562.
CrossRef | Direct Link |
34: Hossain, F., C. E. Pray, Y. Lu, J. Huang, C. Fan and R. Hu, 2004. Genetically modified cotton and farmers health in China. Int. J. Occupational Environ. Health, 10: 296-303.
Direct Link |
35: Huang, J., S. Rozelle, C. Pray and Q. Wang, 2002. Plant biotechnology in China. Science, 295: 674-677.
CrossRef | Direct Link |
36: Jacobsen, C.S., 1995. Microscale detection of specific bacterial DNA in soil with a meagnetic capture-hybridization and PCR amplification assay. Applied Environ. Microbiol., 61: 3347-3352.
Direct Link |
37: James, C., 2004. Preview: Global Status of Commercialized Biotech/GM Crops: 2004. ISAAA Briefs No. 32, International Service for the Acquisition of Agri-Biotech Applications, Ithaca, New York, ISBN: 1-892456-36-2.
38: James, C., 2005. Global Status of Commercialized Biotech/GM Crops. ISAAA, Briefs No. 34, New York, Ithaca.
39: Jones, S., 1994. The Language of the Genes. Flamingo, London, pp: 347.
40: Jung, W., O. Yu, S.C. Lau, D.P. O'Keefe, J. Odell, G. Fader and B. McGonigle, 2000. Identification and expression of isoflavone synthase, the key enzyme for biosynthesis of isoflavones in legumes. Nat. Biotechnol., 18: 208-212.
Direct Link |
41: Kinney, A.J. and S. Knowlton, 1998. Designer Oils: the High Oleic Acid Soybean. In: Genetic Modification in the Food Industry, Rollerand, S. and S. Harlander (Eds.). Blackie, London, UK., pp: 193-213.
42: Kramer, K.J., T.D. Morgan, J.E. Throne, F.E. Dowell, M. Bailey and J.A. Howard, 2000. Transgenic avidin maize is resistant to storage insect pests. Nature Biotechnol., 18: 670-674.
43: Krishnamurty, K. and M.J. Giroux, 2001. Expression of wheat puroindoline genes in transgenic rice enhances grain softness. Nature Biotechnol., 19: 162-166.
44: Kuiper, H.A., E.J. Kok and K.H. Engel, 2003. Exploitation of molecular profiling techniques for GM food safety assessment. Curr. Opin. Biotechnol., 14: 238-243.
45: Lai, J. and J. Messing, 2002. Increasing maize seed methionine by mRNA stability. Plant J., 30: 395-402.
46: Liu, Q., S. Singh and A. Green, 2002. High-oleic and high-stearic cottonseed oils: Nutritionally improved cooking oils developed using gene silencing. J. Am. Coll. Nutr., 21: 205-211.
Direct Link |
47: Longstaff, M., H.S. Edmonds and C.A. Newell, 1995. An improved method for the detection and quantification of recombinant protein in trangenic plants. Plant Mol. Biol. Rep., 13: 363-368.
48: Lucca, P., R. Hurrell and I. Potrykus, 2002. Fighting iron deficiency anemia with iron-rich rice. J. Am. College Nutr., 21: 184S-190S.
Direct Link |
49: Lucca, P., 1999. Genetic engineering approaches to improve the bioavailability and the level of iron in rice grains. Proceedings of the General Meeting of the International Programme on Rice Biotechnology, Sept. 20-24, Phuket, Thailand, pp: 99-99.
50: Lunel, F., M. Mariotti, P. Cresta, I. de la Croix, J.M. Huraux and J.J. Lefrere, 1995. Comparative study of conventional and novel strategies for the detection of hepatitis C virus RNA in serum: Amplicor branched DNA, NASBA and in-house PCR. J. Virol. Methods, 54: 159-171.
51: Mackenzie, S.A., I. Lamb, J. Schmidt, L. Deege and M.J. Morrisey et al., 2007. Thirteen week feeding study with transgenic maize grain containing event DASO15O7-1 in sprague-dawley rats. Food Chem. Toxicol., 45: 551-562.
52: Malatesta, M., M. Biggiogera, E. Manuali, M.B.L. Rocchi, B. Baldelli and G. Gazzanelli, 2003. Fine structural analyses of pancreatic acinar cell nuclei from mice fed on genetically modified soybean. Eur. J. Histochem., 47: 385-388.
53: Malatesta, M., C. Caporaloni, S. Gavaudan, M.B.L Rocchi, S. Serafini, C. Tiberi and G. Gazzanelli, 2002. Ultrastructural morphometrical and immunocytochemical analyses of hepatocyte nuclei from mice fed on genetically modified soybean. Cell Struct. Funct., 27: 173-180.
54: Malatesta, M., C. Caporaloni, L. Rossi, S. Battistelli, M.B.L. Rocchi, F. Tonucci and G. Gazzanelli, 2002. Ultrastructural analysis of pancreatic acinar cells from mice fed on genetically modified soybean. J. Anat., 201: 409-415.
CrossRef | Direct Link |
55: Malatesta, M., C. Tiberi, B. Baldelli, S. Battistelli, E. Manuali and M. Biggiogera, 2005. Reversibility of hepatocyte nuclear modifications in mice fed on genetically modified soybean. Eur. J. Histochem., 49: 237-242.
56: Malley, L., N.E. Everds, J. Reynolds, P.C. Mann and I. Lamb et al., 2007. Subchronic feeding study of DAS-59122-7 maize grain in sprague-dawley rats. Food Chem. Toxicol., 45: 1277-1292.
57: Mayer, J.E., 2005. The golden rice controversy: useless science or unfounded criticism. BioScience, 55: 726-727.
CrossRef | Direct Link |
58: Mayer, J.E., 2007. Delivering golden rice to developing countries. JAOAC Int., 90: 1445-1449.
59: McCue, K.F., L.V.T. Shepherd, P.V. Allen, M.M. Maccree, D.R. Rockhold, H.V. Davies and W.R. Belknap, 2003. Modification of steroidal alkaloid biosynthesis in transgenic tubers containing an antisense sterol glyco transferase (Sgt) gene encoding a novel steroidal alkaloid diglycoside rhamnosyl transferase. Proceedings of the 87th Annual Meeting of the Potato Association of America, Aug. 10-14, Spokane, Wash, pp: 26-26.
60: Mehta, R.A., T. Cassol, N. Li, N. Ali, A.K. Handa and A.K. Mattoo, 2002. Engineered polyamine accumulation in tomato enhances phytonutrient content, juice quality and vine life. Nature Biotechnol., 20: 613-618.
61: Meyer, R., 1995. Nachweis gentechnologisch veranderter Lebensmittel mittels Polymerase Kettenreaktion (PCR). Mitt. Gebiete Lebensm. Hyg., 86: 648-656.
62: Meyer, R., U. Candrian and J. Luthy, 1994. Detection of pork in heated meat products by the polymerase chain reaction. J. AOAC Int., 77: 617-622.
63: Moisyadi, S., K.R. Neupane and J.I. Stiles, 1998. Cloning and characterization of a cDNA encoding xanthosine-N7-methyltransferase from coffee (Carica papaya L.). Acta Hortic., 461: 367-377.
64: Momma, K., W. Hashimoto, H.J. Yoon, S. Ozawa and Y. Fukuda et al., 2000. Safety assessment of rice genetically modified with soybean glycinin by feeding studies on rats. Biosci. Biotechnol. Biochem., 64: 1881-1886.
65: Morgan, C.L., D.J. Newman and C.P. Price, 1996. Immunosensors: technology and opportunities in laboratory medicine. Clin. Chem., 42: 193-209.
Direct Link |
66: Muir, S.R., G.J. Collins, S. Robinson, S. Hughes and A. Bovy et al., 2001. Overexpression of petunia chalcone isomerase in tomato results in fruit containing increased levels of flavonols. Nature Biotechnol., 19: 470-474.
67: Noteborn, H.P.J.M., M.E. Bienenmann-Ploum, J.H.J. van den Berg, G.M. Alink and L. Zolla et al., 1995. Safety Assessment of the Bacillus thuringiensis Insecticidal Crystal Protein CRYIA(b) Expressed in Transgenic Tomatoes. In: Genetically Modified Foods Safety Aspects, Engel, K.H., G.R. Takeoka and R. Teranishi (Eds.). American Chemical Society, Washington, DC., pp: 134-147.
68: Padgette, S.R., Q.K. Huynh, S. Aykent, R.D. Sammons, J.A. Sikorski and G.M. Kishore, 1988. Identification of the reactive cysteines of Escherichia coli 5-Enolpyruvyl-shikimate-3-phosphate synthase and their nonessentiality for enzymatic catalysis. J. Biol. Chem., 263: 1798-1802.
Direct Link |
69: Padgette, S.R., Q.K. Huynh, J. Borgmeyer, D.M. Shah and L.A. Brand et al., 1987. Bacterial expression and isolation of Petunia hybrida 5-Enolpyruvyl-shikimate-3-phosphate synthase. Arch. Biochem. Biophys., 258: 564-573.
70: Padgette, S.R., K.H. Kolacz, X. Delannay, D.B. Re and B.J. LaVallee et al., 1995. Development, identification, and characterization of a glyphosate-tolerant soybean line. Crop Sci., 35: 1451-1461.
Direct Link |
71: Paine, J.A., C.A. Shipton, S. Chaggar, R.M. Howells and M.J. Kennedy et al., 2005. Improving the nutritional value of Golden Rice through increased pro-vitamin A content. Nat. Biotechnol., 23: 482-487.
CrossRef | Direct Link |
72: Poulsen, M., S. Kroghsbo, M. Schroder, A. Wilcks and H. Jacobsen et al., 2007. A 90- day safety study in Wistar rats fed genetically modified rice expressing snowdrop lectin Galanthus nivalis (GNA). Food Chem. Toxicol., 45: 350-363.
73: Poulsen, M., M. Schroder, A. Wilcks, S. Kroghsbo and R.H. Lindecrona et al., 2007. Safety testing of GM-rice expressing PHA-E lectin using a new animal test design. Food Chem. Toxicol., 45: 364-377.
74: Gatehouse, A.M., J.A. Gatehouse, M. Bharathi, J. Spence and K.S. Powell, 1998. Immunohistochemical and developmental studies to elucidate the mechanism of action of the snowdrop lectin on the rice brown plant hopper, Nilaparvata lugens (Stal). J. Insect. Physiol., 44: 529-539.
75: Prakash, C.S., M. Egnin and J. Jaynes, 2000. Increasing the Protein Content in Sweet Potato using a Synthetic Storage Protein Gene. American Chemical Society, AGFD69, Chicago, pp: 219.
76: Prakash, C.S., 1997. Biotechnology used to fortify rice with Iron. Plant Research News. ISB News Report, http://www.isb.vt.edu/articles/dec9702.htm.
77: Prakash, C.S., 2001. The genetically modified crop debate in the context of agricultural evolution. Plant Physiol., 126: 8-15.
Direct Link |
78: Pray, C.E., J. Huang, D. Ma and F. Qiao, 2003. Impact of Bt cotton in China. World Dev., 29: 813-825.
79: Rapp, W., 2002. Development of soybeans with improved amino acid composition. Proceedings of the 93rd AOCS Annual Meeting and Expo, May 5-8, 2002, American Oil Chemist's Society Press, Canada, Champaign, pp: 79-86.
80: Rein, D., E. Schijlen, T. Kooistra, K. Herbers and L. Verschuren et al., 2006. Transgenic flavonoid tomato intake reduces C-Reactive Protein in human C-Reactive Protein transgenic mice more than wild-type tomato. J. Nutr., 136: 2331-2337.
Direct Link |
81: EFSA GMO Panel Working Group on Animal Feeding Trials, 2008. Safety and nutritional assessment of GM plants and derived food and feed: The role of animal feeding trials. Food Chem. Toxicol., 46: S2-S70.
82: Rhee, G.S., D.H. Cho, Y.H. Won, J.H. Seok and S.S. Kim et al., 2005. Multigeneration reproductive and developmental toxicity study of bar gene inserted into genetically modified potato on rats. J. Toxicol. Environ. Health A 68: 2263-2276.
83: Robinson, J., 1999. Ethics and transgenic crops: A review. Electron. J. Biotechnol., 2: 71-81.
84: Roller, S.R. and S. Hallander, 1998. Genetic Modification in the Food Industry: A Strategy for Food Quality Improvement. Aspen Publishers, Frederick, Maryland, USA.
85: Rooke, L., F. Bekes, R. Fido, F. Barro and P. Gras et al., 1999. Overexpression of a gluten protein in transgenic wheat results in greatly increased dough strength. J. Cereal Sci., 30: 115-120.
86: Rosati, C., R. Aquilani, S. Dharmapuri, P. Pallara and C. Marusic et al., 2000. Metabolic engineering of beta-carotene and lycopene content in tomato fruit. Plant J., 24: 413-419.
87: Saiki, R.H., S. Scharf, F. Faloona, K.B. Mullis, G.T. Horn, H.A. Ehrlich and N. Arnheim, 1985. Enzymatic amplification of beta-globulin genomic sequences and restriction site analysis for diagnosis of sickle cell anemia. Science, 230: 1350-1354.
88: Schroder, M., M. Poulsen, A. Wilcks, S. Kroghsbo and A. Miller et al., 2007. A 90-day safety study of genetically modified rice expressing Cry1Ab protein (Bacillus thuringiensis toxin) in Wistar rats. Food Chem. Toxicol., 45: 339-349.
89: Schwall, G.P., R. Safford, R.J. Westcott, R. Jeffcoat and A. Tayal et al., 2000. Production of very-high-amylose potato starch by inhibition of SBE A and B. Nature Biotechnol., 18: 551-554.
90: Setamou, M., J.S. Bernal, J.C. Legaspi and T.E. Mirkov, 2002. Parasitism and location of sugarcane borer (Lepidoptera: Pyralidae) by Cotesia flavipes (Hymenoptera: Braconidae) on transgenic and conventional sugarcane. Environ. Entomol., 31: 1219-1225.
91: Shintani, D. and D. DellaPenna, 1998. Elevating the vitamin E content of plants through metabolic engineering. Science, 282: 2098-2100.
92: Siritunga, D. and R.T. Sayre, 2003. Generation of cyanogen-free transgenic cassava. Planta, 217: 367-373.
93: Smeekens, S., 1997. Engineering plant metabolism. Trends Plant Sci., 2: 286-288.
94: Stark, D.M., K.P. Timmerman, G.F. Barry, J. Preiss and G.M. Kishore, 1992. Role of the amount of starch in plant tissue by ADP glucose pyrophosphorylase. Science, 258: 287-292.
95: Stoger, E., S. Williams, P. Christou, R.E. Down and J.A. Gatehouse, 1999. Expression of the insecticidal lectin from snowdrop (Glanthus nivalis agglutinin; GNA) in transgenic wheat plants: Effects on predation by the grain aphid Sitobion avenae. Mol. Breed., 5: 65-73.
Direct Link |
96: Tada, Y., M. Nakase, T. Adachi, R. Nakamura and H. Shimada et al., 1996. Reduction of 14-16 kDa allergenic proteins in transgenic rice plants by antisense gene. FEBS Lett., 391: 341-345.
97: Tudisco, R., P. Lombardi, F. Bovera, D. D`Angelo and M.I. Cutrignelli et al., 2006. Genetically modified soya bean in rabbit feeding: detection of DNA fragments and evaluation of metabolic effects by enzymatic analysis. Anim. Sci., 82: 193-199.
98: UPI, 2002. Wheat Inhibits Colon Cancer. United Press International, Washington, DC.
99: Uzogara, S.A., 2000. The impact of genetic modification of human foods in the 21st century: A review. Biotechnol. Adv., 18: 179-206.
PubMed | Direct Link |
100: Van Loon, A.P.M.G., H.P. Hohmann, W. Bretzel, M. Humbelin and M. Pfister, 1996. Development of a fermentation process for the manufacture of riboflavin. Chimia, 50: 410-412.
101: Vecchio, L., B. Cisterna, M. Malatesta, T.E. Martin and M. Biggiogera, 2004. Ultrastructural analysis of testes from mice fed on genetically modified soybean. Eur. J. Histochem., 48: 448-454.
102: Bout, S. and W. Vermerris, 2003. A candidate-gene approach to clone the sorghum Brown midrib gene encoding caffeic acid O-methyltransferase. Mol. Genet. Genimics, 269: 205-214.
CrossRef | Direct Link |
103: Wainwright, P.E., Y.S. Huang, S.J. de Michele, H. Xing, J.W. Liu, L.T. Chuang and J. Biederman, 2003. Effects of high-c-linolenic acid canola oil compared with borage oil on reproduction, growth and brain and behavioral development in mice. Lipids, 38: 171-178.
104: Wang, Z.H., Y. Wang, H.R. Cui, Y.W. Xia and I. Altosaar, 2002. Toxicological evaluation of transgenic rice flour with a synthetic cry1Ab gene from Bacillus thuringiensis. J. Sci. Food Agric., 82: 738-744.
105: Welch, R.M., 2002. Breeding strategies for biofortified staple plant foods to reduce micronutrient malnutrition globally. J. Nutr., 132: 495S-499S.
Direct Link |
106: White, C.L., L.M. Tabe, H. Dove, J. Hamblin and P. Young et al., 2001. Increased efficiency of wool growth and live weight gain in Merino sheep fed transgenic lupin seed containing sunflower albumin. J. Sci. Food Agric., 81: 147-154.
107: White, T.J., 1996. The future of PCR technology: diversification of technologies and applications. Trends Biotechnol., 14: 478-483.
108: Wood, D.C., L.V. Vu, N.M. Kimack, G.J. Rogan, J.E. Ream and T.E. Nickson, 1995. Purification and characterization of neomycin phosphotransferase II from genetically modified cottonseed (Gossypium hirsutum). J. Agric. Food Chem., 43: 1105-1109.
Direct Link |
109: Yang, S.H., D.L. Moran, H.W. Jia, E.H. Bicar, M. Lee and M.P. Scott, 2002. Expression of a synthetic porcine alpha-lactalbumin gene in the kernels of transgenic maize. Transgen Res., 11: 11-20.
110: Yang, J.S., T.A. Yu, Y.H. Cheng and S.D. Yeh, 1996. Transgenic papaya plants from Agrobacterium-mediated transformation of petioles of in vitro propagated multishoots. Plant Cell Rep., 15: 459-464.
CrossRef | Direct Link |
111: Ye, X., S. Al-Babili, A. Kloti, J. Zhang, P. Lucca, P. Beyer and I. Potrykus, 2000. Engineering the provitamin A (β-Carotene) biosynthetic pathway into (Carotenoid-free) rice endosperm. Science, 287: 303-305.
CrossRef | Direct Link |
112: Zdunczyk, Z., J. Juskiewicz, J. Fornal, B. Mazur-Gonkowska and A. Koncicki et al., 2005. Biological response of rat fed diets with high tuber content of conventionally bred and transgenic potato resistant to necrotic strain of potato virus (PVYN). Part II. Caecal metabolism, serum enzymes and indices of non-specific defence of rats. Food Control., 16: 767-772.
113: Zhang, X., J. Liu and Q. Zhao, 1999. Transfer of high lysine-rich gene into maize by microprojectile bombardment and detection of transgenic plants. J. Agric. Biotechnol., 7: 363-367.
114: Zhu, Y., D. Li, F. Wang, J. Yin and H. Jin, 2004. Nutritional assessment and fate of DNA of soybean meal from roundup ready or conventional soybeans using rats. Arch. Anim. Nutr., 58: 295-310.