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Genetic Engineering

of Plants & Animals

Genetic Engineering: Changing the genetic make-up of an organism using biotechnological methods

GE: Genetically Engineered Foods

GM: Genetically Modified Foods

GMO: Genetically Modified Organisms

Transgenic Crops

• Make crops, livestock, etc. more profitable -- Pest resistance, herbicide resistance, shortened growth period, traits preferred by consumer

• Make medically important substances easy to obtain -- Enzymes, proteins, tissues

• Make transgenic animals for medical and biological research

-- Disease models, gene function studies

Common Applications of GE

Examples of GE crops

• Starlink and Bt Corn: Resistant to common pests

• Tomatoes: “Flavr- Savr” Slow softening ripe tomatoes

• Herbicide resistant soybeans and cotton: “Round-up” Ready

• Tear-free onions (development in progress)

How do you make a GE crop?

• Identify gene that encodes trait of interest

• Transfer DNA into plant cells via bacteria or a gene gun.

• The DNA integrates into the plant’s chromosomes

• Culture the modified plant cells to grow many cells with the desired trait

• Grow the plant cells in a special culture that causes the cells to differentiate

• The plantlets are transferred from the laboratory culture to soil

Cold tolerance

Cold tolerance

Delivery and Integration

Culture and Differentiate

http://www.agwest.sk.ca/sabic_index_tp.shtml

Bt and Starlink Corn

Different forms of the toxin (Cry proteins) can be used to target specific pests

Can be up to 99% effective

Insects can develop resistance

Starlink corn scare

Bacillus thuringiensis (Bt): Soil bacterium that produces a toxin targeting the gut of common pests of corn, such as the European corn borer

Flavr-Savr Tomatoes: Antisense Technology

The PG gene was identified in the tomato and inserted into a plasmid in such a way that a PG antisense transcript is produced

The antisense transcript binds the PG sense mRNA blocking access of the translational machinary eliminating 99% of the PG product

Polygalacturonase (PG): an enzyme expressed during ripening causing depolymerization of the pectin fraction of the cell wall, which results in softening of ripe tomatoes.

Coding

Noncoding

PGGP

GP

Add CMV promoter

Delivery and Integration

Antisense suppression of PG

Isolate DNA

GE Animals

Quick growing Salmon

Healthier Pork

Allergy-proof Cats

“Super Salmon”

A growth hormone in Salmon is normally produced only in warm temperatures

An antifreeze protein was discovered in flounder that is expressed only in cold temperatures

The control elements from the flounder gene were placed upstream of a copy of the salmon growth hormone gene

The salmon with the transgene grow during the warm and cold seasons

Healthier Pork

FAD2 is found in spinach and converts saturated fats into linoleic acid (an unsaturated fat)

The gene was placed in a pig’s genome

The transgenic pigs contain 20 percent less saturated fat

This is the first time a planet gene has been inserted into an animal genome

Cat allergies are thought to be caused by a single protein in the cat’s skin and saliva.

An allergen-free cat could be available by the year 2003, costing somewhere in the region of $1000

The researchers aim to take cat cells and knock out the gene that produces the problem protein, replacing it with an inactive version.

The cell’s nucleus will then be put into a cat egg cell, that has had its own genes removed, creating an embryo that can be implanted into a surrogate mother.

Allergy Proof Cats

Making Medicine though Genetic Engineering

Turning animals (and plants) into pharmaceutical factories

Goat’s Milk

Anti-cancer tomatoes

Pigs for organ harvest

Malaria Free Mosquitoes

Goat milk drug production

Insert gene for antithrombin III (anti-coagulate) into goat genome with necessary signals for secretion into milk

Purify protein from goat’s milk

Drug prevents blood clotting in patients with antithrombin deficiency (homozygous recessive)

Cancer Preventative Tomatoes

Lycopene is a carotenoid that gives tomatoes their red color

It is an antioxidant; carotenoids capture electrically charged oxygen molecules that can damage tissue

People that eat lots of fruits and vegetables containing lycopene have less breast and prostate cancers

A yeast gene is expressed in the tomato that stabilizes the lycopene and results in 3X the amount of lycopene

Pigs for Organ Harvesting

• Xenotransplantation is limited by immune response of recipient

• The rejection response occurs when human antibodies attach to sugar molecules on the surface of the transplanted pig organ's cells, killing the cells

• The gene that produces this sugar molecule, called a-1,3-galactosyltransferase (GGTA1) has been eliminated in a line of miniature swine

• The swine also have organs approximately the same size as human organs

Malaria-Free Mosquitoes

Malaria is a deadly parasite transmitted to humans via mosquitoes

SM1 gene: prevents malaria from entering salivary gland from mosquito gut

SM1 was placed under control of a promoter controlled by feeding in the mosquito genome

Mosquitoes with SM1 were unable to transmit malaria to mice

To effectively eliminate transmission transgenic mosquitoes must be able to survive as well or better than wildtype mosquitoes

Are GE products safe?

Usually involve random insertion into genome

Includes promoters (CaMV) and enhancers that can influence activity of nearby native genes (may activate normally unactive genes such as toxins)

Gene inserted is usually for a foreign protein that could have undesirable effects in addition to the desired effects

Many of the proteins have not previously been eaten in food -- how will consumer be affected?

Fusion proteins / protein folding

Environmental Issues

Cross pollination / breeding with wild species

Production of “super weeds”

Impact on other species (such as the monarch)

• The US and Canada produce 82% of the world’s GM food.• In 1999 almost one-quarter of our nation's food and fiber crops were genetically engineered• US GE Crops: 57% of U.S. soybeans, 38% of U.S. corn, 65% of U.S. cotton, 4% of U.S. potatoes, and over 50% of the U.S. and Canadian canola crop• 60% of processed foods sold in grocery stores contain at least a trace of GM ingredients

Have you eaten GM Food?

What do people think about GE?

US, China, and Canada: ~75% of consumers approve

Europe and Japan: Less accepting of GM food (less than 20% approve)

But…knowledge about GE is lacking in the general public

European Survey: Would you buy GM food?

Animals for ResearchTransgenic Mice, Plants, Flies, etc.

Transgenic animals can be created to study gene function and/or human disease genes

Can make a variety of changes to yield information-- Null alleles (insert an antibiotic resistance gene in exon)-- Point mutations -- Deletion mutations (eliminate part of a gene or protein)-- Duplications-- Hypomorphic mutation – changes level of gene expression-- Controlled expression of gene in different spatial or temporal context

ES cell from brown mouse

Construct to Disrupt Gene of Interest (GOI)

NEO

Transform and select

NEO

GOI

Let ES cells divide

Inject into blastocyst from white mouse and implant in pseudopregnant female

Look for chimeric progeny

Test chimeras for germ-line transmittance

of brown genome

Links of interest...

Trangenic Pets: http://www.transgenicpets.com/

News Collections: http://www.newscientist.com/hottopics/gm/

http://www.agbiotechnet.com/topics/Database/index.asp

http://greennature.com/article299.html

Overview: http://members.tripod.com/c_rader0/gemod.htm

Labeling GM foods: http://www.thecampaign.org/

Pros and Cons: http://scope.educ.washington.edu/gmfood/

Activist Page: http://archive.greenpeace.org/~geneng/