Singapore’s position on GM food is on par with international practice. The Agri-Food & Veterinary Authority (AVA) ensures that GM food are subjected to extensive assessments and approval in other developed countries before they are made available in the Singapore market. Labelling of GM food is also not requirement as making it mandatory will curtail supplies thereby, increasing the prices of food. Nonetheless, the Genetic Modification Advisory Committee (GMAC) and AVA will continue to ensure that labelling requirements in Singapore are in accordance with the latest international developments. Besides, AVA is developing acceptable guidelines on the labelling of GM food with the help of the international Codex Committee on Food Labelling.
Reference:
http://www.ava.gov.sg/NR/rdonlyres/1693236D-7808-4260-BADE-DB7EA7861BEE/20483/STGMFOOD.pdf
Wednesday, June 25, 2008
Genetic Engineering Technologies (rDNA technology): Microinjection
In this process, DNA is directly injected into cells. Some of these cells will survive and integrate the injected DNA. This method is labour intensive and inefficient compared to other methods.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Genetic Engineering Technologies (rDNA technology): Electroporation
This method is quite similar to somatic hybridization. Instead of fusing two cells together, like in somatic hybridization, this technique fuses the protoplast with the added DNA in the culture medium. An electrical pulse is also used in this method. The transformed cell will then reconstruct its cell wall and grow to a whole, fertile plant. However, the inability for most plant species to regenerate from protoplasts makes this method ineffective.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Genetic Engineering Technologies (rDNA technology): Genetic Engineering Agent (Agrobacterium tumefaciens)
The genetic engineering agent that is responsible for the majority of GM crops is a soil microbe called Agrobacterium tumefaciens. Upon infecting a host cell, this pathogen transfers a segment of its own DNA into the plant cell. The host cell then expresses the transferred genes and the instructions for the production of substances that induce the development of a crown gall (disease) will begin. These substances will then be distributed throughout the plant, causing the food produced by these plant to also contain these substances. By exchanging the crown gall disease-causing DNA with a DNA of interest, new strains of this bacterium can be obtained to introduce new useful genetic material into the host plant. Eventually, the progeny of this whole fertile plant would also contain the same inserted DNA of interest.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Genetic Engineering Technologies (rDNA technology): Microprojectile Bombardment
This is an effective, physical method of DNA delivery in species such as corn, rice and other cereal grains is. In this process, “naked” DNA is adhered to microscopic pellets and shot into plant cells.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Non-genetic Engineering Method: Mutation Breeding
This method involves the exposing of organisms (plants or seeds) to mutagens, be it chemical mutagens or ionizing radiations. These mutagens will induce random changes in the DNA pattern of the organism. The progeny of these mutagenized and matured organisms are then assessed for novel traits. This method produces random effects and is prone to forming mutations that are injurious to human health.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Non-genetic Engineering Method: Somaclonal Variation
When plant cells are grown in vitro (eggs from female ovary are removed and fertilized with male sperm in a laboratory procedure, and then the fertilized egg (embryo) is re-planted in the female), spontaneous mutations will occur, producing progenies with new traits. This method is capable of producing potentially valuable variants in a range of different crops has been largely substituted with more predictable methods.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Non-genetic Engineering Method: Somatic Hybridization
In somatic hybridization, cells are grown in culture mediums where their cell walls are degraded by enzymes such as pectinase, cellulase and hemicellulase, forming protoplasts. These protoplasts are gathered from different sources and fused via electrical shock. This cell fusion technique is easily accomplished but few organisms are capable of growing into a whole, sexually-capable organism.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Non-genetic Engineering Method: Embryo Rescue
At times, human intervention is needed for interspecies gene transfer because the hybrid embryo is unable to mature and sprout. Thus, the hybrid embryo is removed quickly and placed in a tissue-culture where it can reach maturity. This embryo rescue technique allows genes to be transferred from distant, incompatible relatives through intermediate, mildly compatible relatives of both donor and recipient species.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Non-genetic Engineering Method: Interspecies crossing
In interspecies crossing, portions of chromosomes from distant species are recombined via chromosomal translocation. This chromosome engineering referred to as nonrecombinant deoxyribonucleic acid (rDNA) cytogenetic manipulations, is a limiting technique. This is because large portions of chromosomes are transferred in this process including the “bad “genes. Therefore, this method is becoming more competitive with rDNA technology whereby smaller portions of chromosomes, containing the genes of interests, are transferred.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Non-genetic Engineering Method: Simple Selection
Traditionally, “superior” individuals of organisms with the most ideal characteristics are identified and propagated for several years till the population is dominated by the “superior” genotype. This simple selection process can be hastened by the modern marker-assisted selection method, which analyses organisms molecularly to detect individuals with genes that express desired traits. Upon selection and propagation, a “superior” organism is crossed with another “superior” organism to produce a hybrid progeny which displays the combined desired traits of its parents.
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
Adapted from: Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
How are foods genetically modified?
Genetic modification includes non-genetic engineering methods and genetic engineering technologies. Both types of methods can be used to alter the genetic makeup of an organism.
However, genetic engineering technologies, which utilizes rDNA technology, is more specific and precise than non-genetic engineering methods. This technology targets an intended change in a gene to cause a specific result.
1. Non-genetic Engineering Methods
- Simple selection
- Interspecies crossing
- Embryo rescue
- Somatic hybridization
- Somaclonal variation
- Mutation breeding
2. Genetic Engineering Technologies (rDNA technology)
- Micro projectile bombardment
- Genetic engineering agent, Agrobacterium tumefaciens
- Electroporation
- Microinjection
Reference
Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
However, genetic engineering technologies, which utilizes rDNA technology, is more specific and precise than non-genetic engineering methods. This technology targets an intended change in a gene to cause a specific result.
1. Non-genetic Engineering Methods
- Simple selection
- Interspecies crossing
- Embryo rescue
- Somatic hybridization
- Somaclonal variation
- Mutation breeding
2. Genetic Engineering Technologies (rDNA technology)
- Micro projectile bombardment
- Genetic engineering agent, Agrobacterium tumefaciens
- Electroporation
- Microinjection
Reference
Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects, Institute of Medicine and National Research Council of the National Academies, 2004, The National Academy Press
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