genetically modified foods vvv

8/4/2019 Genetically Modified Foods VVV

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Genetically Modified Foods

Dr.M.KANNANDepartment of Microbiology,V.H.N.Senthikumara Nadar College,Virudhunagar 626 001


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Have you ever eaten any genetically

modified food?

Can you tell the difference between a

genetically modified organism and a non-GMorganism?

Do GM foods taste any different? Could they?


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Before Reading Any Further

What is the first impression youget when you hear genetically

modified foods?


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Is it

? or

1


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What is a Genetically Modified (GM)

Food?

Foods that contain an added genesequence

Foods that have a deleted gene sequence

Animal products from animals fed GMfeed

Products produced by GM organisms


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Also called genetically modified organisms (GMO). Involves the insertion of DNA from one organism into

another OR modification of an organisms DNA in

order to achieve a desired trait.

+

A strawberry

resistant tofrost=

4 5

Arctic fish DNA strawberry


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What are GMs?

are a result of technology that has altered the

DNA of living organisms (animals, plants or

bacteria)

Other terms that mean the same thing:

Genetically engineered

Transgenic Recombinant DNA (rDNA) technology


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How does this differ from Mendel and his

peas?

GM vs. Selective breading

Selective breading

-slow

-imprecise

-modification of genes that naturally occur in the organism

GM

-very fast

-precise

-can introduce genes into an organism that would not occurnaturally!


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Examples of GMOs

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.


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Common GM Food

GM Food~Plants 10

Tomato Maize

PastaCabbage


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Why produce GM food?

To improve the quality of foodTo improve food production to feed theworld

To strengthen the resistance against herband pests

To cope better with climatic changes

To minimize the cost of production

To minimize loss during transport andstorage

GM Food~Plants 11


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Why do it?

Rice- not high in essential nutrients

Modification:

+ daffodil genes and a bacterium = beta-carotenecontent drastically increased

+ genes from a french bean = double the ironcontent.

Tomatoes- Introduce genes to increase shelflife.


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Worldwide, 40 % of

our food productiondepends on

irrigation. Depletion

of aquifers isoccurring at twice the

re-charge rate.

Salinization is a major

consequence of

irrigation


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Environmental Hazards from Pesticides

Substantial healthimpacts on workers

Pollution of naturalecosystems/waterways

Loss of insectbiodiversity in agro-ecosystems

Creation of secondarypests

Creation of insectraces resistant to

pesticides


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What is genetic modification?

Does genetic modification only happen in plants?

No, the first gene was transferred into bacteria.

What are some reasons for genetic modification?

Express recombinant insulin in bacteria

What are some of the benefits and some of the

disadvantages of GM foods?


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Many of the same techniques are

used to make a genetic

modifications as to detect one

Polymerase Chain Reaction (PCR) Restriction enzymes

Gel electrophoresis

Transformation


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How is genetic modification

possible?

The components of DNAare the same in all

organisms.

Sequences that code forproteins can be moved

from one organism toanother.


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How can DNA be moved from one organism

to another?

Its quitesimple,

REALLY!!!


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How can DNA be moved from one organism

to another?

Find an organism with the desired

traitIsolate the gene sequence that codesfor the desired trait

Insert the gene sequence into thegenome of the plant cell


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Genetic Engineering

Genetic Engineers can alter

the DNA code of living

organisms.

Selective Breeding

Recombinant DNA

PCR

Gel Electrophoresis

Transgenic Organisms


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Selective Breeding

Breed only those plantsor animals withdesirable traits

People have been usingselective breeding for1000s of years with

farm crops anddomesticated animals.


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Recombinant DNA

The ability to combinethe DNA of oneorganism with the DNAof another organism.

Recombinant DNAtechnology was first

used in the 1970s withbacteria.


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Recombinant Bacteria1. Remove bacterial DNA (plasmid).

2. Cut the Bacterial DNA withrestriction enzymes.

3. Cut the DNA from anotherorganism with restrictionenzymes.

4. Combine the cut pieces of DNAtogether with another enzyme andinsert them into bacteria.

5. Reproduce the recombinantbacteria.

6. The foreign genes will be expressedin the bacteria.


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Restriction Enzymes


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Restriction enzymes are also called restriction

endonucleases They cut double stranded DNA at sequence specific

sites They can produce sticky ends or blunt ends

depending on the enzyme

Sticky Ends

Sticky Ends

Blunt Ends

Blunt Ends

Restriction Enzymes


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1978 Nobel Prize in Medicine was awarded to DanielNathans and Hamilton Smith for the discovery of

restriction endonucleases

Restriction enzymes were discovered in E.colias a defense

mechanism against bacterial viruses (bacteriophages)

The recognition sites are usually 4-12 nucleotides

long

Sequences are palindromic (GAATTC)

There are hundreds of restriction enzymes currently

being used

Restriction Enzymes


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Restriction Enzymes


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Polymerase Chain Reaction

PCR

PCR allows scientists tomake many copies of apiece of DNA.

1. Heat the DNA so itunzips.

2. Add the complementarynitrogenous bases.

3. Allow DNA to cool so thecomplementary strandscan zip together.
http://www.sumanasinc.com/webcontent/animations/content/pcr.html


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Invented in 1983 by Kary Mullis (Nobel Prize in 1993for its discovery)

Uses primers to exponentially amplify a specificregion of DNA

Components needed for the reaction: DNA

Primers to region of interest

DNA polymerase (Taq used to synthesize the DNA) dNTPS (the building blocks of the copied DNA)

Buffer (with appropriate salts to ensure the enzyme worksproperly)

PCR
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Three steps of the reaction: Denaturation: High heat (94-98o) to separate the strands of

DNA

Annealing: (50-60o depends on the primers) this step

allows the primers to bind to the denatured DNA strands Elongation (74o) DNA polymerase synthesizes the new

strand

This step is dependant on the length of the product to beamplified (1min/1kb of DNA)

Check products with gel electrophoresis andsequencing

PCR
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PCR: Cycles
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PCR: Thermocycler
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Gel Electrophoresis

This technology allows

scientists to identify

someones DNA!
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Steps Involved in Gel Electrophoresis

1. Cut DNA sample withrestriction enzymes.

2. Run the DNA fragments througha gel.

3. Bands will form in the gel.

4. Everyones DNA bands are uniqueand can be used to identify a

person.

5. DNA bands are like geneticfingerprints.
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Gel Electrophoresis

Gel electrophoresis is used to separate nucleicacids (DNA and RNA) or proteins for analytical use

DNA and RNA are separated using agarose

Proteins are separated using polyacrylamide

The gel is a matrix (cross-linked polymers) that allowproducts to be separated

Separation is based on the size (based on charge)of a product as it moves through a charged field


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Gel Electrophoresis

The negative charge is at the top (closest tothe samples) and the positive charge is at thebottom

Samples are negatively charged and will travel

towards the positive charge DNA and RNA are negative because of their sugar-

phosphate backbone

Proteins are denatured to give a constant shape and

given a charge through the negative loading bufferused

Samples are diluted in a loading buffer thathelps the samples stay in the wells


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Gel Electrophoresis

Applications

Separating restriction digests

Analyzing/purifying PCR products Sequencing

Protein analysis


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Gel Electrophoresis


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Gel Electrophoresis

Sample agarose gel stained with ethidium bromide (EtBr)


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How are animals targeted?

The microinjection

method uses a fine

needle to inject asolution of DNA into a

developing embryo.6


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How are plants targeted?

A particle gun is used to shoot

small bits of metal coated with

the gene into the plant.

Agrobacterium that normally normallyinfects plants with disease is used to infectplant with gene of interests or

7


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The DNA of plants and animals

can also be altered.

PLANTS

1. disease-resistant andinsect-resistant crops

2. Hardier fruit

3. 70-75% of food insupermarket is geneticallymodified.


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How to Create a Genetically

Modified Plant

1.Create recombinantbacteria with desiredgene.

2. Allow the bacteria toinfect" the plant cells.

3. Desired gene is insertedinto plantchromosomes.


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How is this done?: Transgenic tomatoes


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What do you think about eating genetically

modified foods?


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Genetically modified organisms are called

transgenic organisms.

TRANSGENIC ANIMALS

1. Mice used to study humanimmune system

2. Chickens more resistant toinfections

3. Cows increase milk supply andleaner meat

4. Goats, sheep and pigs producehuman proteins in their milk


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Human DNA ina Goat Cell

This goat contains a humangene that codes for a bloodclotting agent. The bloodclotting agent can be harvestedin the goats milk.

.

Transgenic Goat


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Desired DNA

isadded to an

egg cell.

How to Create a Transgenic Animal

Molecular agriculture makes new gene combinations possible


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Molecular agriculture makes new gene combinations possible

Peas (on the left) that make a genetically engineeredbean protein are insect-resistant and do not need tobe sprayed with pesticides.


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Ha Ha Ha!

d


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Genetic Engineering and

Crime Scenes


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Roundup Ready Gene

The glyphosate resistance gene protects food plantsagainst the broad-spectrum herbicide Roundup,which efficiently kills invasive weeds in thefield. The major advantages of the "Roundup

Ready system include better weed control,reduction of crop injury, higher yield, and lowerenvironmental impact than traditional weed controlsystems. Notably, fields treated with Roundup

require less tilling; this preserves soil fertility bylessening soil run-off and oxidation.


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Herbicide Resistance

Herbicides, like glyphosate and glufosinate, areused to eliminate weeds to maintain nutrientcontent in the soil but they decrease the yield.

Scientists insert the herbicide resistance genes viaagrobacterium into food plants so that they willnot be affected by the herbicide.

This reduces the excessive use of herbicide.

GM Food~Plants 53


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Pest resistance

Scientists insert the toxin producing gene fromBacillus thuringienus, a kind of soil bacterium,into maize.

Destructive insects will be killed when eating thecrop.

The loss due to destructive insects is greatly

reduced.

GM Food~Plants 54


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Other applications

Potato - modified to produce a beetle killing toxin Yellow squash modified to contain to viral genes

that resistant the most common viral diseases

Develop foods that contain vaccines and antibodies

that offer valuable protection against diseases suchas cholera, hepatitis, and malaria

Canola modified to resist one type of herbicide orpesticide

l


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GM CanolaCanadian-Australian Relations

Bayer CropScience produces genetically modified canola in Australia for

the Canadian market. It is produced to resist the herbicide Liberty and can

yield up to 20% higher than conventional canola.

B fit f G ti E i i
http://www.bayercropscience.com/


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Benefits of Genetic Engineering

and Modifying

1. Higher yielding crops, more efficient use of land

2. Can save money and promote higher profits

3. Longer shelf life, less wasteExample// Tomatoes from genetically

modified seeds stay fresh

longer.

4. Enhanced taste and quality

5. Reduced maturation time
http://www.cdc.gov/nccdphp/dnpa/5aday/month/exotic_vegetables.htm


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Importance of GM crops

Worldwide, 9 percent theglobal primary crop

production from genetically

modified crops

2006: over 100 millionhectares in 22 countries

64% of total soya crop and

24% of the global maize

crop


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Importance (2)

Many processed foods

contain Soybean oil

and/or glucose syrup

(from corn)

Difficult to avoid food

containing genetically

modified material,

especially in the USA


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Animal feeds

Likewise animal feeds

commonly contain corn

and soybean meal from

GM crops

Also in Europe GM

material was found in

milk and meat

Some GM crops will improve the


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Some GM crops will improve the

nutritional quality of foods. Such foods are

now in the pipeline.


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Labels are not neutral!

Produced by

RadiationBreeding!

Truthful labels can be misleading or meaningless


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There are no GM apples anywhere!

Is food labeled this waynutritious?

Truthful labels can be misleading or meaningless


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How to Label?

Conventionallygrown

GMO

Pesticides, twice a week Pesticide free

Should foods from GM crops be labeled?


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Should foods from GM crops be labeled?

Perhaps!

The US takes the view that if

foods are substantially equivalent,the method of producing them

need not be on the label.

Farmers use a variety of techniques, and keeping

production streams separate from plow to platecosts money. Such separation is called identity

preservation. Who should pay for this?


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How common are GM foods?

48 foods have

been

approved for

use by the

Canadian

Food

InspectionAgency.

ProductsCornCanola

PotatoesTomatoesSquashSoybeans

FlaxCottonseedoilSugarbeets

Derived

Products

Corn syrupTofuCanned foodsSoya sauceAnimals that

feed onGMOs.AND MORE


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How common are GMO foods?

Labeling of GM foods is not mandatory unless ifthereis a health or safety concern (Health Canada/CanadianFood Inspection Agency)

8


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Who Uses this technology

The Countries that Grow 99% of the

World's Transgenic Crops

69%

23%

7% 1%

USA

Argentina

Canada

China


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Potential Environmental Hazards

Reduced

effectiveness of

pesticides as insects

become resistant toengineered toxins.

Loss of biodiversity

Harm to other organismsPollen from Bt corn was shown to

cause high mortality rates inmonarch butterfly larvae(9). BUT

follow-up studies have shown

that the exposure levels in thefields are negligible(10).

11


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Potential Environmental Hazards

Gene Transfer to non-target species

Herbicide resistant plants and weeds could cross

breed and create superweeds

To address this one could: Create sterile male plants that dont produce pollen

Engineer the plants so that pollen doesnt contain the

foreign genes

Create buffer zones of non-GM crops around GM

crops. The buffer crops would not be harvested.


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Potential Human Health Risks

Allergens

Genetic engineering could potential introduce or create

allergens

For example, inserting genes from a nut into another

plant could be dangerous for people who are allergic to

nuts

Unknown health risks

Biological processes involve a lot of INTERACTIONS It is often difficult to identify every possible interaction.


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Economic Hazards

Elimination of competition

GM seeds are patented

Suicide seeds

Plants with sterile seeds that are infertile are

created

Farmers are forced to buy seeds every year

However, some companies have reduced costsor donated GM seeds to impoverished nations.


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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 thebenefits against the

costs.

Improved Nutrition

Resistance todisease

Reduced use ofchemicals

Environmental risks

Health risks

Economic risks


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Religion and choice?

What happens if vegetarians eat food whichis genetically engineered with an animal gene?

Will it repel choice of food?

GM Food~Plants 74


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Solutions

Add labels to the packages

Improve genetic modification technology

Food tests

GM Food~Plants 75


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Concern: Food Safety

GM food is not labeled as such The industry argues GM crops

are substantially equivalent

to their conventional

counterparts Consequently no need for

special considerations

concerning safety

Label GMO free opposed


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Risks with GM continued:

Biodiversity

Addition of Bt gene into plants including corn, potatoes andcotton to increase resistance to plants

Bt gene obtained from Bacillus thuringiensis (a soil bacteriumthat produces a natural insecticide)

Problem: plants producing Bt toxin are releasing toxin inpollen

Draper, D. (2002). Our Environment: A Canadian Perspective 2nd Ed. Scarborough: Thompson Canada Lmt.

Pollen from a Bt plant was dusted on to milkweed:


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Pollen from a Bt plant was dusted on to milkweed:

- only 56% of young monarch butterfly larvae lived

- whereas pollen from organic plants dusted on the

milkweed produced a survival rate of 100%.Approximately half of the monarch butterflypopulation live in the corn belt of the USA

= this new gene could have serious repercussions for

this organism

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