Genetically Engineered Foods

1
Genetically Engineered Foods

• Techniques, Benefits and Risks

2
Genetically Engineered Foods

• Background on Genetic Engineering
• Methods of transferring genetic material
• Traits of genetically altered plants
• Traits of genetically altered animals
• Environmental and health concerns
• Regulation in the U.S.

3
Background

• Goal to introduce, enhance or delete a
  particular characteristic
• plant breeding, hybridization
• recombinant DNA technology specific genetic
  fragments isolated and inserted in a different
  organism - accomplished through alteration of DNA

4
Basics of Genetic Engineering

• DNA molecule double helix structure
• strands consisting of sugars and phosphates
• series of bases arranged along the strands
  Adenine, thymine, cytosine, and guanine
• sequence of bases determined the specific
  characteristics of the organism
• Transcription resulting in mRNA, which is a
  reverse copy
• Translation tRNA carrying amino acids connect to
  mRNA

5
Recombinant DNA Technology

• Enzymes proteins used to catalyze specific
  reactions -
• many derived from bacteria used as tools to
  manipulate DNA
• Gene Splicing
• Restriction Enzymes cuts DNA, leaves sticky
  ends which attach to bases of DNA from another
  source
• Ligase Enzymes creates strong bond

6
Methods of Transferring Genetic Material

• Vector vehicle for transfer
• usu. Bacterial plasmids
• Agrobacterium is most common natural soil
  bacterium causing crown gall disease in plants by
  inserting part of its own plasmid into the host
  DNA
• GEs encode and clone desired trait in lab,
  incorporate into plasmid and infect plant
• seeds of infected plant grow plant with
  engineered trait
• But, cant be used on monocots (rice, wheat,
  maize) only on dicots (potatoes, tomatoes,
  soybeans)

7
Methods of Transferring Genetic Material (contd)

• Vectorless transmission
• Gene guns fire tiny metal particles coated with
  DNA into tissue culture of cells
• direct injection into nucleus - generally used
  for genetic engineering of animals
• Gene Silencing suppression of gene to prevent
  expression of protein
• Marker Genes used to determine successful
  transformation - luciferase, antibiotic
  resistance markers

8
Traits of Genetically Altered Plants

• Herbicide Resistance
• spraying herbicides to kill weeds can also injure
  crops
• herbicides are broken down naturally by bacteria
  in soil
• GEs transfer detoxifying enzymes from soil
  bacteria to plants
• 2 methods (1) genes that express proteins that
  degrade the herbicide (2) alter sensitivity or
  quantity of enzymes that an herbicide acts upon
  to kill plant
• Monsantos RoundupTM-Ready Soybeans overproduce
  EPSPS

9
Traits of Genetically Altered Plants (contd)

• Pest-resistance
• prevents crops from having to be sprayed with
  costly and hazardous chemical pesticides
• Most common stratey using genes from Bacillus
  Thuringiensis (B.t.) , soil bacteria that
  expressed proteins toxic to insects
• biodegradable and safe for humans and non-target
  organisms
• 1995 EPA approved sale of first B.t. commercial
  crops Monsantos New LeafTM potato
• Limitations specific to certain groups of
  insects, trouble achieving high enough levels of
  toxins

10
Traits of Genetically Altered Plants (contd)

• Disease resistance and stress tolerance
• GE also to create resistance to disease-causing
  viruses, bacteria and fungi
• Resistance to conditions such as frost and
  drought
• gene from Winter Flounder, Arctic fish, inserted
  into potato and tomato and increased tolerance to
  cold temperatures

11
Traits of Genetically Altered Plants (contd)

• Designer Foods
• GE Tomato wanted firmer, redder
• 2 methods of gene silencing
• suppress the gene expressing PG, the enzyme
  responsible for breaking down the cell walls
• suppress the gene that expresses ethylene, which
  promotes the ripening process
• Other traits sweeter berries, higher levels of
  protein in vegetables
• Other uses for GE crops cotton for blue jeans

12
Traits of Genetically Altered Animals

• Genes transferred to animals generally produce
  growth hormones
• Recombinant BST GE in cows to increase milk
  production
• Humans linked to higher levels of insulin grown
  factor-1, which may trigger premature grown in
  infants and breast cancer
• animal promotes increase in mastisis and other
  fertility disorders
• Other traits lower fat levels and increased
  disease resistance in animals

13
Concerns

• Ecological Risks
• Transgenic crops will become weeds
• will act like exotic species and invade other
  areas
• Genes will escape into other plants that will
  become weeds
• hybridization with wild relatives and create
  superweeds
• Pests will develop resistance to
  pesticide-producing plants
• concern over loss of B.t. as an insecticide

14
Concerns (contd)

• Human Health Concerns
• increase in allergic reactions when genes from
  other foods or animals that express certain
  proteins are transferred
• antibiotic resistance marker genes may be
  transferred to bacteria that lives in the gut of
  humans and animals - may reduce the
  effectiveness of antibiotics

15
Concerns (contd)

• Other concerns
• impact on farmers, particularly in developing
  countries
• Not able to use seeds from one year to next
  patenting and Terminator
• Ethical/moral concerns
• religious groups unable to eat certain foods
• vegetarians
• welfare of animals
• playing with Mother Nature

16
Regulation

• GE foods regulated by 3 different agencies USDA,
  FDA, EPA
• apply several different statutes, not one
  comprehensive law regulating
• Many claim patchwork approach is not ensuring
  the safety of these products
• Survey conducted 97 of Americans want labeling
  of GE foods
• Regulation should not be left to the industry