Transcript lec 3

Before Reading Any Further…
What is the first impression you get
when you hear “genetically modified”
foods?
What is a Genetically Modified
(GM) Food?
 Foods that contain an added gene
sequence
 Foods that have a deleted gene sequence
 Animal products from animals fed GM
feed
 Products produced by GM organisms
+
Arctic fish DNA
=
strawberry
A strawberry
resistant to
frost
Examples of GMO’s
 In 1994, the Flavr Savr tomato was introduced as the first
GM food. It is supposed to be "tastier, firmer and fresher”
than the average tomato.
 Golden rice – rice that contains beta-carotene (Vitamin A),
which is not found in regular rice.
 Bt corn – corn that contains a chemical normally found in a
bacterium (Bacillus thuringiensis) that is toxic to insects but
not to humans.
 Herbicide resistant plants - These plants are immune to a
certain herbicide, so they live while all the other plants in the field
are killed
Why are foods genetically modified?
Genetic engineering offers a rapid and
precise method of altering organisms
as compared to traditional methods
that are slow and inaccurate.
How is genetic modification
possible?
The components of
DNA are the same in
all organisms.
Sequences that code
for proteins can be
moved from one
organism to another.
How can DNA be moved from one organism to
another?
How can DNA be moved from one organism to
another?
►Find an organism with the desired
trait
►Isolate the gene sequence that codes
for the desired trait
►Insert the gene sequence into the
genome of the plant cell
How can DNA be moved from one organism to
another?
►Allow the genetically altered
cell to grow into a plant
►Allow the plant to propagate
Modifying Genes

Also called recombinant DNA technology,
molecular cloning, and genetic engineering.
1. Restriction enzymes
are used to “cut” DNA
segments from one genome.
2. DNA ligases
are used to “paste” them into
another genome.
Foreig
n DNA
How can DNA be moved from one organism to
another?
A vector can carry
DNA. The vector can
be a pellet from a gene
gun. Viruses and
bacteria also can be
utilized to transfer
genes.
How common are GM foods?
48 foods have
been
approved for
use by the
Canadian
Food
Inspection
Agency.
Products
Corn
Canola
Potatoes
Tomatoes
Squash
Soybeans
Flax
Cottonseed oil
Sugarbeets
Derived Products
Corn syrup
Tofu
Canned foods
Soya sauce
Animals that feed on
GMOs…
….
AND MORE
Details can be found at: http://www.hc-sc.gc.ca/food-aliment/mh-dm/ofb-bba/nfiani/e_novel_foods_and_ingredient.html
What is grown globally?
 In 2001 the area of genetically modified crops grown
globally was 52.6 million hectares. That is an area the size
of France or Spain. This includes food and non-food crops
(I.e.cotton)
 4 countries produced 99% of the world's genetically modified crops.
These are:




USA (68%)
Argentina (22%)
Canada (6%)
China (3%)
 More than 80% of canola grown in Canada and a high
proportion of the country’s soybean and corn crops are
genetically modified.
Image credit: Microsoft clipart
How common are GMO foods?
8
Labeling of GM foods is not mandatory unless if
there is a health or safety concern (Health
Canada/Canadian Food Inspection Agency)
From ( U.S. Dept. Agriculture 2001)
Bt Maize
 Bacillus thuringiensis
produces a bacterial toxin
(Delta-endotoxin)
 The bacterium has been used
as an insecticide since 1938
 It stops the insect from
feeding by attacking the
insect gut lining
Image Credit: Bacillus thuringiensis
Cry gene
 The toxin is produced by the Cry
gene
 Found on plasmids in the
bacterium
 The gene is added to the genomes
of crop plants using a bacterium
that forms root nodules in plants
(Agrobacterium tumificiens)
 Bt crops produced from 1996
onwards: maize, potato, cotton,
soybean
© 2010 Paul Billiet ODWS
Image Credit: GMO Compass
BT Maize
Advantages
 Only insects attacking the crop will be poisoned
Environmentally friendly
 All tissues are protected even the roots
 Biodegradable – does not accumulate in the food chain
© 2010 Paul Billiet ODWS
Disadvantages
 Pollinators may be killed too
 Pesticide resistance in insects is rapid – but crop
management could limit this
 Pollen grains could spread the gene to wild relatives of
the crop plant
 Technology expensive
Possible Benefits
of GM Foods
Improved crop quality
 Development of frost resistant
crops
 Development of disease
resistant crops
 Development of flood resistant
crops
Improved nutritional
quality
 Development of foods designed to
meet specific nutritional goals
Possible Benefits
of GM Foods
Reduced use of
pesticides and
herbicides
►Development of pest
resistant crops
►Reduced herbicide
use is better for the
environment and
reduces costs for
farmers
Benefits
Phytoremediation
 plants like poplar
trees clean up the
heavy metal soil
contamination

GM plants with higher
tolerance for heavy
metals like mercury.
Image credit: Microsoft clipart
Benefits
 Future benefits might include:
 food without allergens; (I.e. anyone could eat nuts)
 grains, fruit & vegetables with improved nutrition




(multi-vitamin potatoes=healthy fast food french fries!)
longer shelf life and better taste (reduced food waste due
to spoilage)
rice enhanced with iron (prevent anemia)
foods used as vaccines (bye-bye needles)
Many more possibilities
Image credit: Microsoft clipart
Potential Benefits
Humanitarian:
Pest resistance
Herbicide
resistance
Cold tolerance
Drought
tolerance
Increased nutrition
Improved
farming
Cheaper
food
More food
Reducing
world
hunger and
improving
world
health
Edible vaccines
Environmental: reduced use of herbicides
and chemicals in farming.
Challenges #1
 Environmental – possibility of unintended
harm to other organisms:
 potential risk of harm to non-target organisms, e.g. a
pest resistant crop that produces toxins that may
harm both crop-damaging and non crop-damaging
insects

E.g. The pollen of BT corn on milkweed is thought to
affect (slow or kill) the larvae of Monarch butterflies.
Further studies are underway.
Image credit: http://www.public-domain-photos.com/ & Microsoft clipart
Challenges #2
 pesticides become less effective as pests
become resistant to modified crops.
 Different varieties and strengths of pesticides will be
needed once weeds have adapted to the existing effective
pesticides.
Image credit: Microsoft clipart
Challenges #3
 “Superweeds”
 gene transfer to non-target species where herbicide
tolerant plants crossbreed with weeds potentially
creating herbicide resistant weeds.

Some Western Canadian farmers are calling
Monsanto’s round-up ready canola a
superweed.
Image credit: Microsoft clipart
Challenges #4
 Human health risks
 introducing a gene into a
plant may create a new
allergen or cause an allergic
reaction in susceptible
individuals
 For example, inserting genes
from a nut into another plant
could be dangerous for
people who are allergic to
nuts
Image credit: Microsoft clipart
Challenges #5
 Economic Hazards
 Elimination of competition
 GM seeds are patented (must buy each year)
 This presents problems for poor farmers in both the developed and
developing worlds.
 Large companies like Monsanto have resorted to suing
small farmers found to be using their seed without paying.
 Suicide seeds
 Plants with sterile seeds that are infertile are created
 Farmers are forced to buy seeds every year
 However, some companies have reduced costs or
donated GM seeds to impoverished nations.
Image credit: Microsoft clipart
Creating a balance
 So are GM foods a
good or bad thing?
 It depend on each
individual case.
 Consumers, the
government and
scientists should be
responsible for
weighing the
benefits against the
Improved Nutrition
costs.
Resistance to disease
Reduced use of
chemicals
Environmental risks
Health risks
Economic risks