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The Science of Transgenics. The Sociological, Economic, and Ethical Impact of Transgenic Organisms Workshop Fargo, ND February 21, 2003. Phil McClean Department of Plant Science North Dakota State University. Transgenics are a Biotechnology Product. How about some definitions.

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slide1

The Science of Transgenics

The Sociological, Economic, and Ethical Impact

of Transgenic Organisms Workshop

Fargo, ND

February 21, 2003

Phil McClean

Department of Plant Science

North Dakota State University

slide2

Transgenics are a Biotechnology Product

How about some definitions

Biotechnology - General Definition

The application of technology to improve

a biological organism

Biotechnology - Detailed Definition

The application of the technology to improve

the biological function of an organism

by adding genes from another organisms

slide3

What About the Term

Genetic Engineering?

Genetic engineering is the basic tool set of biotechnology

Genetic engineering involves:

  • Isolating genes
  • Modifying genes so they function better
  • Preparing genes to be inserted into a new species
  • Developing transgenes
slide4

What is a transgenic?

Concept Based on the Term Transgene

Transgene – the genetically engineered gene added to a species

Ex. – modified EPSP synthase gene (encodes a protein that functions even when plant is treated with Roundup)

Transgenic – an organism containing a transgene introduced by technological (not breeding) methods

Ex. – Roundup Ready Crops

slide5

Why are transgenics important?

We can develop organisms that express a “novel” trait not normally found in the species

Extended shelf-life tomato (Flavr-Savr)

Herbicide resistant soybean (Roundup Ready)

slide6

Agriculture Transgenics On the Market

  • Insect resistant cotton – Bt toxin kills the
  • cotton boll worm
  • transgene = Bt protein

Source: USDA

  • Insect resistant corn – Bt toxin kills the
  • European corn borer
  • transgene = Bt protein

Normal

Transgenic

slide7

Herbicide resistant crops

  • Now: soybean, corn, canola
  • Coming: sugarbeet, lettuce, strawberry
  • alfalfa, potato, wheat (2005?)
  • transgene = modified EPSP synthase or
  • phosphinothricin-N-acetyltransferase

Source: Monsanto

  • Virus resistance - papya resistant to
  • papaya ringspot virus
  • transgene = virus coat protein
slide8

Biotech chymosin; the enzyme used

  • to curdle milk products
  • transgene = genetically engineered enzyme

Source: Chr. Hansen

  • bST; bovin somatotropin; used to increase
  • milk production
  • transgene = genetically engineered enzyme

Source: Rent Mother Nature

slide9

Some Ag Biotech Products Are Discontinued

Why???

  • Poor Quality
  • FlavrSavr tomatoes (Calgene)
  • Negative Consumer Response
  • Tomato paste (Zeneca)
  • Negative Corporate Response
  • NewLeaf (Monsanto)
  • Universal Negative Publicity
  • StarLink corn (Aventis)
slide10

Next Generation of Ag Biotech Products

Golden Rice – increased Vitamin A content

(but not without controversy)

transgene = three pathway enzymes

Sunflower – white mold resistance

transgene = oxalate oxidase from wheat

Source: Minnesota

Microscopy Society

slide11

Turfgrass – herbicide resistance;

slower growing (= reduced mowing)

Bio Steel – spider silk expressed in goats; used to

make soft-body bullet proof vests (Nexia)

slide12

Biotechnology is Not Just on the Farm

Disease Treatment

Diagnostics

Environmental Cleanup

Human Applications

slide13

Human Applications

  • Pharmaceutical products
  • New solutions to old problems
  • Disease diagnosis
  • Determine what disease you have or may get 
  • Gene therapy
  • Correcting disease by introducing a corrective gene
slide14

Biotechnology and Health

The genes for these proteins are:

  • Cloned
  • Inserted into bacteria
  • Product isolated using biofermentation
slide15

Environmental Applications

Bioremediation - cleanup contaminated

sites; uses microbes designed to degrade

the pollution

Indicator bacteria – contamination can be

detected in the environment

slide16

Future Health-related Biotech Products

Vaccines – herpes, hepatitis C, AIDS, malaria

Tooth decay – engineered Streptococcus mutans,

the bacteria that destroys enamel

slide17

Edible Vaccines

Transgenic Plants Serving Human Health Needs

  • Works like any vaccine
  • A transgenic plant with a pathogen protein gene is developed
  • Potato, banana, and tomato are targets
  • Humans eat the plant
  • The body produces antibodies against pathogen protein
  • Humans are “immunized” against the pathogen
  • Examples:
    • Diarrhea
    • Hepatitis B
    • Measles
slide18

A Popular Term We Need To Know

GMOs - Genetically modified organisms

  • GMO - an organism that expresses traits that result
  • from the introduction of foreign DNA
  • Originally a term equivalent to transgenic organism
slide19

The GMO Ruse

  • Some claim any improved biological product is a GMO
  • They feel this will
  • ease the publics fear
  • pave the way for product acceptance
  • For example, some call plant varieties biotechnology products
  • This is a false claim
slide20

Let’s Be Up Front

  • Biotechnology adds traits not available in the species
    •  Soybean does not have a gene to breakdown Roundup
    • The gene comes from bacteria
  • Breeding  Biotechnology
    • Breeding only exchanges genes found in the species
    • Breeding can transfer the transgene to other breeding materials
    • BUT this does not make it a biotechnology procedure
slide21

Important Plant Improvement Methods

  • Breeding
  • Crossing two individuals from the same species;
  • produces a new, improved variety;
  • not a biotechnology procedure

Source: USDA

  • Transformation
  • Adding a gene from another species; the
  • essential biotechnology procedure to produce
  • transgenics

Source: USDA

slide22

Interspecific Cross

Wheat

Rye

X

Triticale

New species, but

NOT biotechnology

products

slide23

Mutagenesis

  • A useful procedure to produce a new trait
  • But the normal gene is modified
  • A transgene is not involved
  • The product of mutagenesis is not a GMO
slide24

Mutagenesis Changes the DNA Sequence

Mutagenesis

Treatment

Susceptible

Normal

Gene

ATTCGA

Resistant

Mutant

Gene

ATTGGA

slide25

BASF Clearfield Products

  • Herbicide resistance
    • imidazolinones
  • Mutant AHAS enzyme
    • developed by mutagenesis
  • Crops
    • Canola
    • Corn
    • Rice
    • Sunflower
    • Wheat
  • A Major Marketing Advantage
  • but lost when stacked with a transgene
slide26

The Roundup Ready Story

  • Glyphosate is a broad-spectrum herbicide
  • Active ingredient in Roundup herbicide
  • Kills all plants it come in contact with
  • Inhibits a key enzyme (EPSP synthase) in an amino acid pathway
  • Plants die because they lack the key amino acids
  • A resistant EPSP synthase gene allows crops
  • to survive spraying
slide27

Shikimic acid + Phosphoenol pyruvate

Plant

EPSP synthase

3-Enolpyruvyl shikimic acid-5-phosphate

(EPSP)

Aromatic

amino acids

Roundup Sensitive Plants

+ Glyphosate

X

X

Without amino acids, plant dies

X

X

slide28

Roundup Resistant Plants

Shikimic acid + Phosphoenol pyruvate

+ Glyphosate

RoundUp has no effect;

enzyme is resistant to herbicide

Bacterial

EPSP synthase

3-enolpyruvyl shikimic acid-5-phosphate

(EPSP)

With amino acids, plant lives

Aromatic

amino acids

slide29

The Golden Rice Story

  • Vitamin A deficiency is a major health problem
  • Causes blindness
  • Influences severity of diarrhea, measles
  • >100 million children suffer from the problem
  • For many countries, the infrastructure doesn’t exist
  • to deliver vitamin pills
  • Improved vitamin A content in widely consumed crops
  • an attractive alternative
slide30

IPP

Geranylgeranyl diphosphate

Phytoene synthase

Phytoene

Problem:

Rice lacks

these enzymes

Phytoene desaturase

ξ-carotene desaturase

Lycopene

Lycopene-beta-cyclase

Normal

Vitamin A

“Deficient”

Rice

 -carotene

(vitamin A precursor)

-Carotene Pathway Problem in Plants

slide31

IPP

Geranylgeranyl diphosphate

Phytoene synthase

Phytoene

Vitamin A

Pathway

is complete

and functional

Phytoene desaturase

ξ-carotene desaturase

Lycopene

Lycopene-beta-cyclase

 -carotene

(vitamin A precursor)

Golden

Rice

The Golden Rice Solution

-Carotene Pathway Genes Added

Daffodil gene

Single bacterial gene;

performs both functions

Daffodil gene

slide32

Introducing the Gene

or

Developing Transgenics

Steps

1. Create transformation cassette

2. Introduce and select for transformants

slide33

1. Gene of interest

  • The coding region and its controlling elements

2. Selectable marker

  • Distinguishes transformed/untransformed plants

3. Insertion sequences

  • Aids Agrobacterium insertion

Transformation Cassettes

Contains

slide34

Tissue must be capable of developing into normal plants

  • Leaf, germinating seed, immature embryos
  • Develop shoots
  • Root the shoots

Transformation Steps

Prepare tissue for transformation

Introduce DNA

  • Agrobacterium or gene gun

Culture plant tissue

Field test the plants

  • Multiple sites, multiple years
slide35

Agrobacterium

Tissue culture

required to generate

transgenic plants

  • Gene Gun

Delivering the Gene

to the Plant

  • Transformation cassettes are developed in the lab
  • They are then introduced into a plant
  • Two major delivery methods
slide37

Non-transgenics

Transgenics

The Next Test Is The Field

Herbicide Resistance

slide38

Before

After

Final Test of the Transgenic

Consumer Acceptance

RoundUp Ready Corn