GENETIC
ENGINEERING
By,
Dr. Priyanka Sharma
II year MDS
Department of Public Health Dentistry
JSS Dental College & Hospital 1
1
CONTENTS
1) INTRODUCTION
2) BASICS OF GENETIC ENGINEERING
3) HISTORY OF GENETIC ENGINEERING
4) GENERAL APPLICATION OF GENETIC ENGINEERING
5) GENETIC ENGINEERING IN DENTISTRY
- VARIOUS TECHNIQUES OF GENETIC ENGINEERING
6) GENETIC COUNSELLING & ROLE OF DENTIST
7) SUMMARY
8) CONCLUSION
9) REFERENCES
2
2
INTRODUCTION
Genetic engineering is a part of
biotechnology.
Biotechnology is the use of living
systems and organisms to develop or
make useful products, or "any
technological application that uses
biological systems, living organisms or
derivatives thereof, to make or modify
products or processes for specific use"
(UN Convention on Biological
Diversity, Art. 2).
4
4
INTRODUCTION continuation..
Biotechnology is a huge topic.
Its hard to define its exact boundaries.
Some European scientists divide the field into :
1) Red biotechnology
2) Green biotechnology
Some divides it into :
1) White
2) Blue
Biotechnology falls under many umbrellas
which is basically considered as life science.
Book : Biotechnology & Genetic engineering (Kathy wilson peacock)
5
2010,Edi:1 : Page No. 4 (Chapter 1)
5
7
INTRODUCTION continuation..
• Genetics – science of genes, heredity
and variation in living organisms.
• Genetics deals with the molecular structure
and function of genes, and gene behavior in
context of a cell or organism (e.g. dominance
and epigenetics ).
• Patterns of inheritance from parent to
offspring, and gene distribution, variation and
change in populations = Population genetics.
7
Book : Genetics and the Organism: Introduction
8
INTRODUCTION continuation..
Essence
Of
Genetics
• Chromosome
• Packaged and organized chromatin, a complex of
macromolecules found in cells, consisting of DNA, protein and
RNA.
Essence
Of
Genetics
• DNA
• A molecule that encodes the genetic instructions used in the
development and functioning of all known living organisms and
many viruses.
Essence
Of
Genetics
• Genetic Variation
• Permanent change in the chemical structure of genes brought
about by mutation, important in providing genetic material for
natural selection.
Essence
Of
Genetics
• Heredity
• The study of heredity in biology is called genetics, which includes
the field of epigenetics.
8
Book : Genetics and the Organism: Introduction
BASICS OF
GENETIC ENGINEERING
• Different terms used for genetic
engineering :
1) Gene manipulation
2) Gene cloning
3) Recombinant DNA technology
4) Genetic modification
5) New genetics
An Introduction to Genetic Engineering (Desmond S. T. Nicholl) Edi :3rd 2008
15
Chapter 2 . Page 3
15
Direct manipulation of an organism's
genome using biotechnology .
First isolating and
copying the
genetic material of
interest
using molecular
cloning methods
Generate a
DNA sequence
New DNA
inserted in the host
genome
BASICS OF
GENETIC ENGINEERING CONTINUATION..
An Introduction to Genetic Engineering (Desmond S. T. Nicholl)
Edi :3rd 2008 Chapter 2.
16
17
Miller et al(2000). An Introduction to Genetic Analysis (7th ed.).
17
18
18
CONTENTS
1) INTRODUCTION
2) BASICS OF GENETIC ENGINEERING
4) GENETIC ENGINEERING IN DENTISTRY
- VARIOUS TECHNIQUES OF GENETIC ENGINEERING
5)GENETIC COUNSELLING AND ROLE OF A DENTIST
1) SUMMARY
2) CONCLUSION
3) REFERENCES
Genetic inheritance was first
discovered by Gregor Mendel in 1865
following experiments crossing peas.
• Although largely ignored for 34 years he
provided the first evidence of hereditary
segregation and independent assortment
In 1889 Hugo de Vries came up with the name
"(pan)gene" for after postulating that particles
are responsible for inheritance of characteristics
Term "genetics" was coined by William
Bateson in 1905.
19
In 1928 Frederick Griffith proved the
existence of a "transforming principle" involved
in inheritance, which Avery, MacLeod and
McCarty later (1944) identified as DNA.
Edward Lawrie Tatum and George Wells
Beadle developed the central dogma that genes
code for proteins in 1941.
The double helix structure of DNA was
identified by James Watson and Francis
Crick in 1953.
20
In 1970 Hamilton Smiths lab
discovered restriction enzymes that allowed
DNA to be cut at specific places and separated
out on an electrophoresis gel.
• This enabled scientists to isolate genes from an
organism's genome.
DNA ligases, that join broken DNA together,
had been discovered earlier in 1967 and by
combining the two enzymes it was possible to
"cut and paste" DNA sequences to
create recombinant DNA.
Plasmids, discovered in 1952, became
important tools for transferring information
between cells and replicating DNA sequences.
21
Frederick Sanger developed a method for
sequencing DNA in 1977, greatly increasing the
genetic information available to researchers
Polymerase chain reaction (PCR), developed
by Kary Mullis in 1983, allowed small sections
of DNA to be amplified and aided identification
and isolation of genetic material
Artificial competence was induced
in Escherichia coli in 1970 when Morton
Mandel and Akiko Higa showed that it could
take up bacteriophage λ after treatment with
calcium chloride solution (CaCl2).
22
Two years later, Stanley Cohen showed that
CaCl2 treatment was also effective for uptake of
plasmid DNA.
Transformation using electroporation was
developed in the late 1980s, increasing the
efficiency and bacterial range
In 1972 Paul Berg utilised restriction enzymes
and DNA ligases to create the first recombinant
DNA molecules.
23
• Herbert Boyer and Stanley N. Cohen took
Bergs work a step further and introduced
recombinant DNA into an bacterial cell.
In 1981 the laboratories of Frank Ruddle,
Frank Constantini and Elizabeth Lacy
injected purified DNA into a single-cell mouse
embryo and showed transmission of the genetic
material to subsequent generations.
On June 19, 2013 the leaders of three research
teams who originated the technology, Robert T.
Fraley of Monsanto; Marc VanMontagu of Ghent
University in Belgium and founder of Plant Genetic
Systems and CropDesign ; and Mary-Dell
Chilton ofWashington University in St.
Louis and Syngenta were awarded with the World
Food Prize
Gordon, J.; Ruddle, F. (1981). "Integration and stable germ line transmission 24
of
genes injected into mouse pronuclei". Science 214 (4526): 1244.
The first recorded knockout mouse was created
by Mario R. Capecchi, Martin
Evans and Oliver Smithies in 1989. They are
used to study gene function and make useful
models of human diseases.
In 1992 onco-mice with tumor suppressor
genes knocked out were generated.
Creating Knockout rats are much harder and has
only been possible since 2003
Bacteria synthesising human insulin were
developed in 1979, being used as a treatment for
the first time in 1982
Zan, Y; Haag, J. D.; Chen, K. S.; Shepel, L. A.; Wigington, D; Wang, Y. R.; Hu, R; Lopez-Guajardo, C.
C.; Brose, H. L.; Porter, K. I.; Leonard, R. A.; Hitt, A. A.; Schommer, S. L.; Elegbede, A. F.; Gould, M.
N. (2003). “Production of knockout rats using ENU mutagenesis and a yeast-based screening
25
assay". Nature Biotechnology 21(6): 645–51.
26
In 1988 the first human antibodies were
produced in plants.
The first animal to synthesise transgenic
proteins in their milk were mice, engineered
to produce human tissue plasminogen
activator.
With the discovery of microRNA in 1993
came the possibility of using RNA
interference to silence an organisms
endogenous genes
- Peng, S. (2006). "A transgenic approach for RNA interference-based
genetic screening in mice". Proceedings of the National
Academy of Sciences 103 (7): 2252–2220.
- Vaucheret, H.; Chupeau, Y. (2011). plant miRNAs regulate gene
expression in animals Cell Research 22 (1): 3–5.
27
Improved our
understanding of
genetics.
His research helped to
make organ
transplantations
possible.
Dr. Bernard Amos
27
• His work cloned frogs
laid the foundations
for somatic cell
nuclear transfer, the
application of which
led to Dolly the sheep.
28
John Gurdon
28
• He noticed that there is
a pattern in the 4 bases:
Adenine, Guanine,
Cytosine and Thymine.
32
• A=T and G=C.
Erwin Chargaff
32
In 1973 created
a transgenic
mouse by
introducing foreign
DNA into its embryo,
making it the world’s
first transgenic
animal.
33
Rudolf Jaenisch
33
34
34
CONTENTS
1) INTRODUCTION
2) BASICS OF GENETIC ENGINEERING
3) HISTORY OF GENETIC ENGINEERING
5) GENETIC ENGINEERING IN DENTISTRY
- VARIOUS TECHNIQUES OF GENETIC ENGINEERING
6) 5)GENETIC COUNSELLING AND ROLE OF A DENTIST
7) SUMMARY
8) CONCLUSION
9) REFERENCES
GENERAL APPLICATIONS OF
GENETIC ENGINEERING
][38]
35
Eg: transgenic plants produce natural
pesticide to resist to pest
35
Engineered Mammals
A monkey named ANDi,
for "inserted DNA", in a
picture released in
January 2001. ANDi was
born in October 2000 at
the Oregon Health
Science University after
receiving an extra bit of
genetic material to
become the world's first
genetically modified
non-human primate
36
36
37
Cloning Dolly
• Sheep A: donate body cell nucleus
• Sheep B: donate an egg cell without nucleus
• Sheep C: surrogate mother
A B C
Dolly
37
Who’s its
mother?
38
38
CONTENTS
1) INTRODUCTION
2) BASICS OF GENETIC ENGINEERING
3) HISTORY OF GENETIC ENGINEERING
4) GENERAL APPLICATION OF GENETIC ENGINEERING
6) 5)GENETIC COUNSELLING AND ROLE OF A DENTIST
7) SUMMARY
8) CONCLUSION
9) REFERENCES
TECHNIQUES
OF
GENETIC ENGINEERING
Tools and techniques
Methods in recombinant DNA
technology
Genetically modified organisms
Genetic treatments
40
40
41
TECHNIQUES
OF
GENETIC ENGINEERING
Methods in recombinant DNA
technology
Genetically modified organisms
Genetic treatments
41
DNA: The Raw Material
– Heat-denatured DNA
• DNA strands separate if heated
to just below boiling
• Exposes nucleotides
• Can be slowly cooled and
strands will renature
42
42
Restriction Endo-nucleases
• Enzymes that can clip strands of DNA
crosswise at selected positions
• Each has a known sequence of
4 to 10 pairs as its target
• Can recognize and clip at palindromes
43
43
• Can be used to cut DNA in to smaller
pieces for further study or to remove
and insert sequences.
• Can make a blunt cut or a “sticky end”
• The pieces of DNA produced are
called restriction fragments.
• Differences in the cutting pattern of specific
restriction endonucleases give rise to
restriction fragments of differing lengths-restriction
fragment length polymorphisms.
44
44
Ligase and Reverse Transcriptase
• Ligase: Enzyme necessary to seal
sticky ends together
• Reverse transcriptase: enzyme that is
used when converting RNA into DNA.
46
46
ANALYSIS OF
DNA
Gel
electrophoresis
Polymerase
Chain Reaction
48
48
49
49
Gel electrophoresis: produces a readable
pattern of DNA fragments
GEL ELCTROPHORESIS
• APPLICATIONS:
Estimation of the size of DNA
molecules following restriction
enzyme digestion, e.g. in restriction
mapping of cloned DNA.
Analysis of PCR products, e.g. in
molecular genetic diagnosis or genetic
fingerprinting.
50
50
51
51
• Some techniques to analyze DNA and
RNA are limited by the small amounts of
test nucleic acid available
• Polymerase chain reaction (PCR)
rapidly increases the amount of DNA in a
sample
• So sensitive- could detect cancer from a
single cell
• Can replicate a target DNA from a few
copies to billions in a few hours
53
53
Three Basic Steps that Cycle
• Denaturation
– Heat to 94°C to separate in to two strands
– Cool to between 50°C and 65°C
• Priming
– Primers added in a concentration that favors binding
to the complementary strand of test DNA
– Prepares the two strands (amplicons) for synthesis
• Extension
– 72°C
– DNA polymerase and nucleotides are added
– Polymerases extend the molecule
• The amplified DNA can then be analyzed
54
54
• Relative sizes of nucleic acids
usually denoted by the number of
base pairs (bp) they contain.
• DNA Sequencing: Determining the
Exact Genetic Code
– Most detailed information comes from
the actual order and types of bases-
DNA sequencing
– Most common technique: Sanger DNA
sequence technique
56
56
• Two different nucleic acids can hybridize by uniting at
their complementary regions.
• Gene probes: specially formulated oligonucleotide
tracers
– Short stretch of DNA of a known sequence
– Will base-pair with a stretch of DNA with a
complementary sequence if one exists in the test sample
• Can detect specific nucleotide sequences in unknown
samples.
• Probes carry reporter molecules (such as radioactive or
luminescent labels) so they can be visualized.
• Southern blot- a type of hybridization technique
57
57
• Southern blotting involves the transfer of DNA
from a gel to a membrane, followed by detection
of specific sequences by hybridization with a
labeled probe.
• Northern blotting, RNA is run on a gel.
• Western blotting entails separation of proteins on
an SDS gel, transfer to a nitrocellulose membrane,
and detection proteins of interest using antibodies.
58 FIGURE 21: Southern blot: Identifying Specific DNA Fragments
(Edward Southern--the pioneer)
or gentle vacuum
pressure
Drying or exposure
to UV light
Probes: Isotope or chemical
Gel is soaked in
alkali buffer to
denature DNA
Northern blotting is similar to Southern blotting,
but involves the transfer of RNA from a gel to a
membrane
RNA
59
Northern blotting: Measuring gene activity
Poly(A)+ RNA: from rat tissues
Probe: G3PDH (glyceraldehyde-3-phosphate dehydrogenase)
60
Western blotting
61
• Western blotting entails separation of proteins on
an SDS gel, transfer to a nitrocellulose membrane,
and detection proteins of interest using antibodies.
wikipedia
Blotting Methods
63
• Antibodies can recognize the protein of interest or
an epitope tag.
• epitope tag – A short peptide sequence that
encodes a recognition site (“epitope”) for an
antibody, typically fused to a protein of interest for
detection or purification by the antibody.
Human influenza hemagglutinin (HA): YPYDVPDYA
The HA tag is derived from the HA-molecule corresponding to amino
acids 98-106 has been extensively used as a general epitope tag in
expression vectors.
65
65
• Probes applied to intact cells
• Observed microscopically for the
presence and location of specific
genetic marker sequences
• Effective way to locate genes on
chromosomes
• Gene expression array are used to detect the
level of all the expressed genes in an
experimental sample.
• SNP arrays permit genome-wide genotyping of
single nucleotide polymorphisms. =>use
allele-specific oligonucledtide probe
• Array comparative genome hybridization
(array-CGH) allows the detection of copy
number changes in any DNA sequence
compared between two samples.
66
DNA 67
Microarrays
• DNA microarrays
comprise known DNA
sequences spotted or
synthesized on a small
chip.
Microarrays show the
levels of all the
expressed genes in an
experimental sample.
68
TECHNIQUES
OF
GENETIC ENGINEERING
Tools and techniques
Genetically modified organisms
Genetic treatments
68
69
69
Methods in Recombinant DNA
Technology
• Primary intent of recombinant DNA
technology- deliberately remove
genetic material from one organism and
combine it with that of a different
organism.
• Form genetic clones
– Gene is selected
– Excise gene
– Isolate gene
– Insert gene into a vector
– Vector inserts DNA into a cloning host
71
71
Technical Aspects of Recombinant
DNA and Gene Cloning
• Strategies for obtaining genes in an
isolated state
– DNA removed from cells, separated into
fragments, inserted into a vector, and
cloned; then undergo Southern blotting and
probed
– Gene can be synthesized from isolated
mRNA transcripts
– Gene can be amplified using PCR
• Once isolated, genes can be maintained
in a cloning host and vector (genomic
library)
72
72
Characteristics of Cloning
Vectors
• Capable of carrying a significant piece of the
donor DNA
• Readily accepted by the cloning host
• Must have a promoter in front of the cloned
gene
• Vectors (such as plasmids and
bacteriophages) should have three important
attributes:
– An origin of replication somewhere on the
vector
– Must accept DNA of the desired size
– Contain a gene that confers drug resistance to
their cloning host
CONVENTIONAL APPROACH
77
77
OF TREATMENT
• Enzyme induction by drugs
• Replacement of deficient enzymes /
proteins
• Replacement of deficient vitamin / co-enzyme
• Replacement of deficient product
• Substrate restriction in diet
• Drug therapy
• Drug avoidance
• Replacement of diseased tissue
• Removal of disease tissue
Genomic medicine 78
use of genotypic analysis (DNA
testing) to enhance quality of medical
care, including
78
- presymptomatic
identification
- preventive intervention
- selection of
pharmacotherapy
- design of medical care
79
79
GENE THERAPY
Replacement of a deficient gene /
gene product or correction of an
abnormal gene.
2 TYPES:
i. Germ-line gene therapy – changes
will be passed on to subsequent
generations
ii. Somatic Cell gene therapy –
changes will not be passed on to
future generations
Gene Therapy
• Gene transfer for the purpose of
treating human disease.
• Transfer of new genetic material as
well as manipulation of existing
genetic material.
(Genetic engineering)
in vivo ex vivo
80
Gene therapy
• Pain
Virus vector – mediated transfer of genes
encoding opiate peptides
peripheral & central neurons
Anti-noceptive effects
89
Direct gene delivery – articular surface TMJ
• Keratinocytes Gene therapy – systemic
human aplipoprotein E, factor IX,
growth hormone and IL-10 into
bloodstream.
• DNA vaccinations
Gene therapy
90
Gene therapy
• Gene gun-based DNA vaccination against
infectious diseases – oral mucosa
(Wang J 2003)
• Caries vaccine
91
• Subunit Vaccines
Gene therapy
- synthetic peptide vaccines
- recombinant vaccines
• Conjugate Vaccines
• Routes to Protective Responses
- oral
- intranasal
- tonsillar
- rectal
92
• Adjuvants and Delivery Systems
Cholera & E coli, microcapsules, liposomes
Gene therapy
94
Future Strategies of Gene Therapy
in Preventing Periodontal Diseases
• Gene Therapeutics-Periodontal
Vaccination
• Genetic Approach to Biofilm
Antibiotic Resistance
• An In vivo Gene Transfer by
Electroporation for Alveolar
Remodelling
• Tight Adherence Gene for the Control
of Periodontal Disease Progression
• Antimicrobial Gene Therapy to
Control Disease Progression 94
Anti-angiogenesis
therapy
Transfer
gene to
tumor cells
to block
angiogenesis
Inhibit tumor
progression
Pre-clinical
Drug
resistance
gene therapy
Transfer
cytoprotectiv
e gene
Decrease
toxicity of
chemotherap
y
Clinical trial
Tumor-cell
killing
viruses
Introduce
viruses that
destroy
tumor cells
as part of
replication
cycle
Kill tumor
cells
Pre-clinical
Suicide gene
therapy
Transfer
gene
encoding
pro-drug
activating
enzyme
Kill tumor
cell &
enhance
chemotherap
y
Clinical trial
98
99 HUMAN GENOME
99
PROJECT
Objectives:
i. Sequencing of human genomes
ii. Mapping of human inherited diseases
iii. Development of new DNA
technologies
iv. Development of bio-informatics
v. Comparitive Genomics
vi. Functional Genomics
100
TISSUE ENGINEERING
• Tissue Engineering is a general name
of biomedical fields to enable cells to
enhance their proliferation,
differentiation, and morphological
organization for induction of tissue
regeneration, resulting in regenerative
medical therapy of diseases.
100
101
Stem cells in regenerative medicine
• A stem cell is defined as a cell that can
continuously produce unaltered
daughters and, furthermore, has the
ability to generate cells with different
and more restricted properties.
• These cells can either multiply
(progenitors or transit amplifying cells)
or be committed to terminal
differentiation.
• Stem cells are self-renewing and thus
can generate any tissue for a lifetime.
• This is a key property for a successful
therapy. 101
107
GENETIC COUNSELLING
A process of communication and education
which addresses concerns relating to the
development and / or transmission of a
hereditary disorder.
STEPS IN GENETIC COUNSELLING
107
- Diagnosis
- Risk assessment
- Communication
- Discussion of options
- Long term contact & support
108
108
DIAGNOSIS
• History
• Examination
• Investigation
• Only when accurate diagnosis is
possible
• When etiological heterogeneity is
present
109
RISK ASSESSMENT
The good side of the coin should also
be emphasized
109
ARBITRARY GUIDE
1 in 10 - High risk
1 in 20 - Low risk
Intermediate values - Moderate risk
110
LONG TERM CONTACT &
110
SUPPORT
• Counselling centers should maintain
informal contact with families
through a network of genetic
associates
• Genetics registers provide a useful
means in ensuring effective contact
111
NEONATAL SCREENING
111
To prevent subsequent morbidity
POPULATION CARRIER
SCREENING
The branch of medical genetics
which is concerned with
screening and the prevention of
genetic disease on a population
basis is known as community
genetics.
PRENATAL DIAGNOSIS 112
Ability to detect abnormality in an
unborn child.
112
TECHNIQUES
I. Non invasive
- Maternal Serum screening
- Ultra sound
II. Invasive
- Amniocentesis
- Chorionic Villus Sampling
INDICATIONS FOR 113
113
PRENATAL DIAGNOSIS
• Advanced maternal age
• Previous child with a genetic
abnormality
• Family History of
- Chromosome abnormality
- Single gene disorder
- Neural tube defect
- Other congenital structural
abnormalities
• Abnormalities identified in pregnancy
Eg. Poor fetal growth
114
114
• Other High risk factors
- Parental Consanguinity
- Poor obstetric history
Eg: Recurrent miscarriages
Previous unexplained still
birth
- Maternal illness
Eg: Poorly controlled IDDM
Maternal epilepsy
Treatment with Sodium
Valproate
119
Genetic
engineering
Enabling
technology
Cutting,modifying
and joining DNA
molecules
enzymes
Generation
of DNA
fragments
Restriction
enzyme
DNA Ligase
Joining to a
vector or DNA
Molecule
Introduction
into the host
cell
Selection of
desired
sequence
Arose from
Gene cloning
Recombinant
DNA
Molecular cloning
Pure science,
Biotechnology,
Medicine,
Dentistry
Legal and
ethical
considerations
Microbial &
Molecular
genetics
In 1972
Stanford
University
Is also known as
Has application in
But raises some
was first achieved
Is an
That involves
using
Such as
Requires four steps
Can be used for
used for
CONCLUSION
120
• Biotechnology as a fast developing
technology as well as science , has
already shown its impact on different
aspects of day-to-day human life such
as public health pharmaceuticals, food
and agriculture industries,
bioenergetics and information
technology.
120
121
• As it has potential to ensure food
security, dramatically reduce hunger
and malnutrition and reduce rural
poverty , particularly in developing
countries , Now it is very clear that
biotechnology is the key technology
for the 21st century and the science of
the future.
121
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37. Griffiths, Anthony J. F.; Miller, Jeffrey H.; Suzuki, David T.;
Lewontin, Richard C.; Gelbart, William M., eds. (2000). "Genetics
and the Organism: Introduction". An Introduction to Genetic
Analysis (7th ed.). New York: W. H. Freeman.
38. Book : Biotechnology & Genetic engineering (Kathy wilson
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39. D. L. Hartl and V. Orel (1992). "What Did Gregor Mendel Think
He Discovered?".Genetics 131 (2): 245–25
40. Zambryski, P.; Joos, H.; Genetello, C.; Leemans, J.; Montagu, M.
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128
Notas do Editor
In 1907 a bacterium that caused plant tumors, Agrobacterium tumefaciens, was discovered and in the early 1970s the tumor inducing agent was found to be a DNA plasmid called the Ti plasmid
By removing the genes in the plasmid that caused the tumor and adding in novel genes researchers were able to infect plants with A. tumefaciens and let the bacteria insert their chosen DNA into the genomes of the plants
By removing the genes in the plasmid that caused the tumor and adding in novel genes researchers were able to infect plants with A. tumefaciens and let the bacteria insert their chosen DNA into the genomes of the plants
Genetic engineering has been used to produce proteins derived from humans and other sources in organisms that normally cannot synthesise these proteins. Bacteria synthesising human insulin were developed in 1979, being used as a treatment for the first time in 1982.[48] In 1988 the first human antibodies were produced in plants.[In 1997avidin, an egg protein, was expressed in a plant with the intention of extracting, purifying and selling it.[49] The first transgenic livestock were produced in 1985,[50] by micro injecting foreign DNA into rabbits, sheep and pigs eggs.[51] The first animal to synthesise transgenic proteins in their milk were mice,[52] engineered to produce human tissue plasminogen activator.[53] This technology has now been applied to other sheep, pigs, cows and other livestock.[52]
With the discovery of microRNA in 1993 came the possibility of using RNA interference to silence an organisms endogenous genes. Craig C. Mello and Andrew Fire discovered a silencing effect in 1998 through injection of double stranded RNA into C. Elegans . Using genetic engineering the microRNA can be expressed long term, permanently silencing the target genes. In 2002 stable gene silencing was induced in mammalian cells,[and in 2005 this was accomplished in a whole mouse.[In 2007 papers were released where insect and nematode genes that formed microRNA were put into plants, resulting in gene silencing of the pest when they ingested the transgenic plant.[58]
The development of genetic engineering technology led to concerns in the scientific community about potential risks. The development of a regulatory framework concerning genetic engineering began in 1975, at Asilomar, California. The Asilomar meeting recommended a set of guidelines regarding the cautious use of recombinant technology and any products resulting from that technology.[30] The Asilomar recommendations were voluntary, but in 1976 the US National Institute of Health (NIH) formed a recombinant DNA advisory committee.[31] This was followed by other regulatory offices (the United States Department of Agriculture (USDA), Environmental Protection Agency (EPA) and Food and Drug Administration (FDA)), effectively making all recombinant DNA research tightly regulated in the USA.[In 1982 the Organization for Economic Co-operation and Development (OECD) released a report into the potential hazards of releasing genetically modified organisms into the environment as the first transgenic plants were being developed.[33] As the technology improved and genetically organisms moved from model organisms to potential commercial products the USA established a committee at theOffice of Science and Technology (OSTP) to develop mechanisms to regulate the developing technology.[32] In 1986 the OSTP assigned regulatory approval of genetically modified plants in the US to the USDA, FDA and EPA.[34] In the late 1980s and early 1990s, guidance on assessing the safety of genetically engineered plants and food emerged from organizations including the FAO and WHO.[35][36][37
WHO (1987): Principles for the Safety Assessment of Food Additives and Contaminants in Food, Environmental Health Criteria 70. World Health Organization, Geneva
Jump up^ WHO (1991): Strategies for assessing the safety of foods produced by biotechnology, Report of a Joint FAO/WHO Consultation. World Health Organization, Geneva
Jump up^ WHO (1993): Health aspects of marker genes in genetically modified plants, Report of a WHO Workshop. World Health Organization, Geneva
Jump up^ WHO (1995): Application of the principle of substantial equivalence to the safety evaluation of foods or food components from plants derived by modern biotechnology, Report of a WHO Workshop. World Health Organization, Geneva
n 1976 Genentech, the first genetic engineering company was founded by Herbert Boyer and Robert Swanson and a year later and the company produced a human protein (somatostatin) in E.coli. Genentech announced the production of genetically engineered human insulin in 1978.[59] In 1980, the U.S. Supreme Court in the Diamond v. Chakrabarty case ruled that genetically altered life could be patented.[60] The insulin produced by bacteria, branded humulin, was approved for release by the Food and Drug Administration in 1982.[61] In 1983, a biotech company, Advanced Genetic Sciences (AGS) applied for U.S. government authorization to perform field tests with the ice-minus strain of P. syringae to protect crops from frost, but environmental groups and protestors delayed the field tests for four years with legal challenges.[62] In 1987, the ice-minus strain of P. syringae became the first genetically modified organism (GMO) to be released into the environment[63] when a strawberry field and a potato field in California were sprayed with it.[64] Both test fields were attacked by activist groups the night before the tests occurred: "The world's first trial site attracted the world's first field trasher".[63]
The first field trials of genetically engineered plants occurred in France and the USA in 1986, tobacco plants were engineered to be resistant to herbicides.[65] The People’s Republic of China was the first country to commercialize transgenic plants, introducing a virus-resistant tobacco in 1992.[66] In 1994 Calgene attained approval to commercially release the Flavr Savr tomato, a tomato engineered to have a longer shelf life.[67] In 1994, the European Union approved tobacco engineered to be resistant to the herbicidebromoxynil, making it the first genetically engineered crop commercialized in Europe.[68] In 1995, Bt Potato was approved safe by the Environmental Protection Agency, after having been approved by the FDA, making it the first pesticide producing crop to be approved in the USA.[69] By 2010, according to the annual ISAAA brief: "While 29 countries planted commercialized biotech crops in 2010, an additional 31 countries, totaling 60 have granted regulatory approvals for biotech crops for import for food and feed use and for release into the environment since 1996.... A total of 1,045 approvals have been granted for 196 events (NB: an "event" is a specific genetic modification in a specific species) for 25 crops. Thus, biotech crops are accepted for import for food and feed use and for release into the environment in 60 countries, including major food importing countries like Japan, which do not plant biotech crops. Of the 60 countries that have granted approvals for biotech crops, USA tops the list followed by Japan, Canada, Mexico, South Korea, Australia, the Philippines, New Zealand, the European Union, and Taiwan. Maize has the most events approved (65) followed by cotton (39), canola (15), potato and soybean (14 each). The event that has received regulatory approval in most countries is herbicide tolerant soybean event GTS-40-3-2 with 25 approvals (EU=27 counted as 1 approval only), followed by insect resistant maize MON810 with 23 approvals, herbicide tolerant maize NK603 with 22 approvals each, and insect resistant cotton (MON1445) with 14 approvals worldwide."
strand that contains the same series of nitrogenous bases regardless from which direction the strand is analyzed.