Genetically Modified Foods

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Genetically Modified Foods

• Siddhartha Mitra
• AID NYC
• April 2010

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Topics Covered

• Background
• Definitions
• Effects
• Advantages
• Disadvantages
• Evidence
  
• Future Direction
• Questions

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Background

• Bt Brinjal, Indias (and the worlds) first
  genetically modified food crop has been
  temporarily stopped in India, thanks to a massive
  grassroots campaign.
• Bt Cotton, however, is being cultivated in many
  parts of India. Benefits are doubtful, though
  Doubts exist about its productivity, and has been
  implicated with negative effects, like resistant
  test, high water consumption, farmer suicides,
  etc.

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Definition

• What does Bt stand for?
• Bt stands for Bacillus thuringiensis, which is a
  natural soil bacteria, which secretes a toxin
  that is deadly to two pests - fruit and shoot
  borer (FSB, Leucinodes orbonalis) and fruit borer
  (Helicoverpa armigera).

Cotton bollworm Leucinodes orbonalis
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Definition

• What is a genetic modification?

Insertion of Bt gene in the Brinjal genetic code
Produce the Bt Toxin to kill the pest
But is only the gene introduced? No, a PROMOTER
and an antibiotic resistance MARKER GENE are also
introduced!
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Definition

What is a gene
What is genetic modification
How is it done
Potential effects
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Definition Gene part of a chromosome
Looks like AACCGGCCCTTTTACGTTATTA
Chromosomes
Part of it is a gene AACCGGCCCTTTTACGTTATTA
Genes
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DefinitionGenes produce protein

Cell
Protein
Nucleus
Genetic material
The genes in the genetic code have the template
for creating the proteins
Proteins (extracellular, cell surface, or
intracellular) confer behaviour the phenotype
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DefinitionProtein production occurs at specific
times and places

• GENE EXPRESSION A gene creates proteins only
• at specific times and locations in an organism,
  and in very tightly regulated amounts.
• Example Pancreatic cells have genes for
  producing the insulin protein, and so do cells in
  the eye.

Specific location
Specific amount
Specific time
Expression is tightly regulated
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DefinitionRegulation

• How does regulation occur?
• For a gene to be expressed, specific chemical
  factors need to bind to a PROMOTER region and
  other regulatory region in the genetic code
  upstream of the gene.
• AAACCGGTATAATCCCCTGAGTTTGCCGTTAGTAG

Factor binds promoter
Gene
Regulatory region
Factor binds regulatory region
Promoter
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DefinitionRegulatory region

• Therefore a gene is expressed only when specific
  agents bind to promoter and regulatory regions at
  specific time and at specific cell types (eye
  cell vs pancreatic cell).
• Though promoter sequence are known, information
  about regulatory regions and what factors binds
  to them is mostly unknown.

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Definition BT Gene insertion

• A BT modified brinjal has a BT gene inserted,
  along with a promoter element(Cauliflower Mosaic
  Virus (CaMV) promoter)
• The promoter is so powerful that it keeps the BT
  gene expression turned on at full volume at all
  times in BT Brinjal!
• This could lead to metabolic stress as the plant
  has to keep producing this toxin despite the
  external conditions.

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Definition BT Gene insertion

• A BT modified brinjal has a BT gene inserted,
  along with a promoter element(Cauliflower Mosaic
  Virus (CaMV) promoter)
• ACTGTCTATGTA TACGTATAATGGTAGATTTATATGGG
• TAACTGTCTATGTACGTATAATGGTAGATTTATATGGG

Insertion point
Gene
BT Gene
Promoter
BT Gene Promoter
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Definition Insertion process

• The insertion is carried out using an mobile
  microbial DNA which infects the host cell (for
  dicotyledons like lugumes, or by a gene gun (gold
  pellets carrying fragments of DNA), either which
  performs the random insertion in some of the
  target cells.

Microbial Vector
Target cell
Create primary transformant
Target cell
Target cell
Gene gun
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Definition BT Gene insertion

• Microbial Vector has the genetic sequence of
  toxin present in a part of an insertion sequence.

AACCGTGGTGGGTCCCAATTAGGGTTACCGGGG
The gene gun shoots gold pellets having the
sequence of interest
AACGTTCCGTT
Gold Pellet
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Definition Result of insertion process

Target cell
Target cell
Target cell
Only some of the target cells successfully
incorporate the gene
To identify the successfully converted viable
cells, an antibiotic resistance marker gene IS
ALSO INSERTED
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Definition Resistance marker gene

• AACCGGTTGGTTGGGTTTGGGGGGGCCGGTTAAA

Insertion sequence
Promoter Sequence
Bt gene
Resistance marker gene
The target cells which successfully incorporate
the insert sequence are selected on the basis of
their resistance to an antibiotic
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Definition Result of insertion process

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Definition Create final hybrid variety
Primary transformant bacterial plasmid DNA
(pMON10518)

Hybrid variety MHB 4, 9, 10, 80, 99
Backcross
Final variety Bt MHB
Final variety needs high amounts water and
fertilisers .
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Effects

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Advantages?
Yield not shown to increase in Bt Cotton or GM Soy
Mahyco admits unable to control pests in Gujarat
with Bt Cotton

Increased use of water for Bt cotton
Increase use of pesticides
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Disadvantages
Could lead to genetic contamination
Farmers suicides have doubled in Bt cotton belt
in Vidarbha

Will make us dependent on Monsanto for food
Monoculture will wipe out diversity
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Evidence
Long terms lab tests on rats have all shown
ill-effects
Monsanto made tests only on few rats (10) for
only 3 months

Monsanto / Mahyco uses their own datasets to show
yield increase
Long term human tests not done
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Evidence

• Non-target effects of GM food crops
• 21 reported harmful environmental effects
• 44 reported unexpected changes in plant
  physiology
• 20 reported unpredicted changes in plant
  morphology
• 6 reported a decrease in the food or feed quality
• 4 reported scrambling of both the transgene and
  host DNA

• Effect on animals
• Arpad Putszai paper in the Lancet, showed the
  unpredicted changes
• in the gastro-intestinal mucosa of rats fed with
  GM potato
• A 90-day internal company study on rats fed with
  MON863 Bt-maize showed
• decreased body-weight and severe toxic effects in
  the liver and kidneys
• (c) a 20-week feeding study by the Austrian
  Federal Ministry of Health revealed
• lower fertility and reduced birth weight in mice
  fed with Bt-maize
• (d) a study carried out in the Italian
  governments National Institute of Research on
  Food and Nutrition showed that very young and old
  mice fed with Bt-maize (MON810) for 90 days were
  immunologically compromised

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Future DirectionsDo we really need this?
We already have varieties
Negative effects on farmers

Benefit to corporations
Danger to consumers
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Future Directions
Tissue specific expressions (instead everywhere
like root)
Site-directed, non-random insertion (Gene
stacking Golden rice)

Chlorpolast transformation (instead of nuclear
transformation)
Use safer promoters (CaMV promoter aggressive,
similarity to HIV)
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Future Directions
GM potato, tomato, rice, everything in the waiting
Control of food for the world

BRAI act will make it illegal for
non-scientists to question GM
Loss of diversity will make crops susceptible
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References

• Questions or comments?
• Crop management yield increase of 28 with
  better crop management
• Yield increase 3-4 on average

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Questions

• Questions or comments?