PRESS CONFERENCE GENETIC MODIFIED FOOD

Genetically Modified Food Mechanism of Genetically Modified Food--GM food (There are totally 2 methods) Applications of Genetic Modification Pros and Cons of GM food News Government’s action

Mechanism of GM Food(1) 1)Isolating/synthesizing the target gene 2)Inserting the target gene into a vector, i.e. an intermediate carrier 3)Transferring the vector containing the target gene into a host cell and cloning the DNA 5) Mixing plant cells with host cells

Mechanism1 : Isolating/synthesizing the target gene The ‘shotgun’ approach, using type II restriction enzyme(restriction endonuclease ) - the enzyme cuts at recognition sites, to obtain a desired gene - sticky ends or blunt ends produced (there are figures later) Making a copy of the gene from its mRNA - poly-T oligomer binds to the complementary poly-A tail of the mRNA - a single strand of DNA copy formed - digesting mRNA - a double-stranded cDNA produced

Sticky end and blunt end

Mechanism1 : Inserting the target gene into a vector Step 1) Prepare a target gene with sticky end if it has blunt end - Short pieces of DNA are joined at the end of the gene - restriction enzymes cut linkers Step 2) Prepare the plasmid DNA (a figure later) as vector - centrifugation Step 3) Combine the target gene and the plasmid DNA by DNA ligase - To have the same sticky end, the same restriction enzyme is used to cut the vector

Plasmid DNA Circular DNA(2), which is smaller and lighter than main chromosomal DNA(1)

Mechanism1 : Transferring the vector into a host cell (transformation) and Cloning the DNA Step 1) Adding the plasmid vector into a flask containing culture of a host cell Step 2) Generating temporary pores on the surface of the host cell Step 3) Allowing the plasmid vector to enter the host cell Step 4) Placing the host cell in a dish with nutrients

Mechanism1: Mixing plant cells with host cells Using Agrobacterium tumefaciens or Agrobacterium rhizogenes as vectors Introducing Ti-plasmid into the plant cells The whole plant can be regenerated from a transformed leaf disc

Summary of the mechanism(1)

Mechanism of GM Food(2) Antisense approach Switching off or turning down (underexpressing) a resident gene in the organism Antisense RNA is produced

Applications of Genetic Modification in Food Production GM Food -Tomatoes and tomato paste -Corn maize -GM soya beans GM processing aid -A kind of GM organism making a product without GM material GM ingredients in animal feed

Benefits of GM food higher yields increased muscle bulk (animals) the ability to resist disease, pests or chemicals a prolonged shelf-life higher nutritional value reduced allergens the ability to grow in environments that are usually too hostile.

Disadvantages of GM food Unintended modification of similar species due to cross pollination Upsetting the ecosystem Development of super pests Problems about religious, health, etc Destroying the normal farming system Interfering the normal DNA system Widening the financial gaps between developed and developing countries

News about GM food

out allergenic proteins regulators should demand SOURCES: New Scientist (issue 2530) Letter to the Editor, 17 December 2005 allergenic potential of genetically modified foods (e.g. mouse strains in peas ) Existing tests provide no direct immunological information and cannot rule out allergenic proteins regulators should demand full sequencing of the transgenic proteins in plants

causing a wave of “superweeds” ‘co-existence’ is biologically SOURCES: ISIS Press Release 16December,2005 Genetically modified DNA from any part of a GM plant can enter the environment unobserved causing a wave of “superweeds” ‘co-existence’ is biologically impossible

no existing public records of contamination incidents or other problems associated with GM crops strict rules with liability regulations should be applied by governments to stop the unauthorized spread of GM seeds and products data used by the Government to approve GM foods should be accessed freely

Modified animals: 27%(2003) 32%(2004) SOURCES: BBC News 8 December 2005 Modified animals: 27%(2003) 32%(2004) Total experiments: just over 2.85 million Number of animals used in research: 2.78 million (a rise of 2.1% on 2003 figures)

Within three weeks of birth, - 55% of the rats fed on GM soya died SOURCES: GM Free Cymru [Wales] Press Notice 25thNovember 2005 Within three weeks of birth, - 55% of the rats fed on GM soya died - 9% of the rats died in the control group mice fed on GM soya experienced a slowdown in cellular metabolism and modifications to liver and pancreas introduction of genes from a bean variety into a GM pea led to the creation of a novel protein which caused inflammation of the lung tissue of mice.

What should HK government do? Setting up mandatory labelling system for GM food informing the public the pros and cons of GM foods building up its own expertise with public health professionals and GM food-related scientists

What did China government do? On March 20th 2002 , the Regulations on the Administration of the Safety of Transgenic Agricultural Products (RASTAP) became effective According to RASTAP and its measures, two methods of application are required to control the safety of transgenic products in international trade.

Regulations on the Administration of the Safety of Transgenic Agricultural Products (RASTAP) First, Chinese importers or foreign exporters must apply for the transgenic products which may be imported later to be risk assessed. Second, foreign exporters must label their transgenic products.