Genetically Modified Food

Plan for Today

•Quick foot-and-mouth disease trivia

•Let’s talk about our survey results

•Some background on genetically modified food

A question from last timeFoot-and-mouth (or hoof-and-mouth) disease

• Caused by a virus that affects hoofed animals (cows, pigs, sheep, etc)– Causes blisters on the mouths and feet of infected animals, fever, lack of

appetite, shivering, lack of milk production– Spreads quickly in a herd through direct contact, through the air, and via

shoes/tires– Animals recover in 2-3 weeks, but are usually destroyed before then so don’t

transmit disease to other animals

• Rarely transmitted to humans (and only causes flu-like symptoms in humans)

• No vaccine because virus mutates quickly and is cheaper to deal with outbreaks than pay for immunization

Your assignment from Monday!Tally your responses to each question and write the numbers on the

board:

1)      How effective are antibiotics at fighting colds? 2)      Have you ever taken an antibiotic at a time when you were not

prescribed to do so by a doctor? 3)      Do you use antibacterial soap? 4)      Is it possible for a disease to become resistant to antibiotics? 5)      Is it possible for a human being to become resistant to antibiotics? 6)      Did you know that many farmers (particularly fruit growers) treat

their crops with antibiotics?  Do you know why they do that?

• Are most people well-educated about antibiotics and antibacterial soap?

• Are you surprised by the results?

• What are some practical implications of these results?

And now…genetically modified foods

Which of the following does not qualify as a genetically modified food?

A) Angus cattle

B) Guernsey dairy cows

C) Rhode Island red chickens

D) Broccoli

E) Corn

And now…genetically modified foods

F) None of the above!

There are almost no foods you eat that come from naturally occurring species

Farmers have been selectively breeding, cross-pollinating, etc. for thousands of years

Basic Genetics

• Dominant & Recessive Genes

• Someone might express a dominant gene but carry a recessive gene

• Recessive genes from both sides can appear in subsequent generations

• Plants (or animals or people) can be modified by selecting for desirable traits

Plant Breeding by Trial & Error

• Natural Selection – Darwin • Artificial Selection

– Used for millennia for crop improvement– Select best product for future use

• Artificial selection has led to much more profitable and edible crops– Higher food to waste ratio– Land produces higher yields

Plant Genetic Modification (GM)• Introduce gene or genes artificially• Plants can be described as “transgenic”• Began in late 1970s – development of DNA

manipulation• Gained knowledge of how to cut DNA molecules at

particular points and glue back together – recombinant DNA technology

• How it works: Propagate selected DNA through bacteria propagation– Cut & splice plant genes and then propagate in bacteria

Genetic Modification of the Potato

Genetically Modified Crops, Nigel Halford, 2003

Advantages of GM

• Precision – involve only individual genes that are desirable

• Genes can act on only a specific part of plant or a particular portion of its life cycle

• Safety of protein produced by gene can be studied prior to use in GM program

• Improved crop yields• Improved crop characteristics• Reduce pesticide use – insect resistant and/or

herbicide resistant crops

Disadvantages of GM

• Invest more time & money than program of random mutations

• Barriers and restrictions to GM crop development – regulations in some countries

• Safety????

Potential Safety Concerns

1. Pleiotropy: genes have multiple functions, especially when they work in conjunction with other genes

We may transfer genes that have other functions we don’t want

The genes may develop new functions when they interact with a new genome

Potential Safety Concerns

2. Plasmids: functions (especially undesirable ones) may transfer to other organisms in the environment

3. Pollination: When plants spread seeds, other farms could pick up transgenic traits without realizing it

Potential Safety Concerns

Since transgenic foods haven’t been around long, nobody can study the long-term effects of eating these foods yet

And these are just the safety issues–there’s a lot more to consider!

Golden Rice

The vitamin A-producing gene is taken out of a red pepper and put into rice

Advantage: Could save millions of children world-wide from blindness

Siberian Tomatoes (Strawberries, too)

The anti-freeze-producing gene is taken out of a flounder and put into tomatoes

Advantage: Tomatoes that can be shipped at lower temperatures, less rotting, less waste, and more profit for tomato growers

B.t. Corn

An insecticidal protein from the bacteria Bacillus thuringiensis is put into corn

Advantage: Corn is protected from pests, so chemical pesticides are not necessary

In development: Banana Vaccine

Viral proteins for infectious diseases such as Hepatitis B will be put into bananas

Advantage: Ability to efficiently vaccinate people world-wide

GM Statistics

• In 2001, 6% of total world agriculture was GM crops

• > 50% of world’s soybean crop is genetically modified

• Countries growing GM crops: US, Canada, Argentina, Uruguay, Mexico, Spain, Bulgaria, Ukraine, Romania, China, South Africa, Australia

Questions for you

• Are the benefits of golden rice, siberian tomatoes, B.t. corn, and the banana vaccine worth the risks? Why or why not?

• How do you decide what type of genetically modified food is worth the risk of eating?

• The EU currently bans the importation of live genetically modified plants but does import genetically modified foods. Is this good policy?