Download Themes in Biology - College of Science and Mathematics

BTEC 3301
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Dolly was created by agricultural research
scientists, who were being funded to make the
perfect sheep, for the purposes of more efficient
agricultural production.
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The name "Dolly" came from a suggestion by the
stockmen who helped in the process, in honor of
Dolly Parton, because the cloned cell was a
mammary cell
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After the cloning was successfully demonstrated
by Dolly creators, many other large mammals
have been cloned, including horses and bulls.
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Dolly who became the first famous adult cloned
sheep was successfully cloned in 1996, (July
1996 to Feb 2003) was the first mammal to
have been successfully cloned from adult cells.
She was created at Roslin Institute Scotland and
lived there until her death nearly seven years
later.
Dolly was put down on
Feb 14 2003, due to complications from a lung
infection.
Refer: Fig7.7 for the process.
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Animal biotechnology is the field to
engineer transgenic animals, i.e., animals
that carry genes from other species.
The technology has already produced
transgenic animals such as mice, rats,
rabbits, pigs, sheep, and cows
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A transgenic animal is one whose genome
has been changed to carry genes from
other species.
For example, an embryo can have an
extra, functioning gene from another
source artificially introduced into it, or a
gene introduced which can knock out the
functioning of another particular gene in
the embryo
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Animals that have their DNA
manipulated in this way are known
as transgenic animals.
Transgenic animals are useful as
disease models and producers of
substances for human welfare
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Some transgenic animals are produced for
specific economic traits. For example,
transgenic cattle were created to produce milk
containing particular human proteins, which
may help in the treatment of human
emphysema (A lung disease which involves
damage to the air sacs (alveoli) in the lungs)
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Other transgenic animals are produced as
disease models (animals genetically
manipulated to exhibit disease symptoms so
that effective treatment can be studied
The OncoMouse® or the Harvard mouse,
carrying a gene that promotes the
development of various human cancers
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DNA microinjection:
Introducing the transgene DNA
directly into the zygote at an early
stage of development. No vector
required
Retrovirus-mediated gene transfer:
Infecting mouse embryo with a
retrovirus which carry the new gene.
Using virus as a vector .
Embryonic stem cell-mediated gene transfer:
 The blastocyst (inner layer of a fertilized
egg) is harvested and mixed with
recombinant DNA and inserted back in
the blastocyst
Sperm-mediated transfer:
 Use of “Linker protein" to attach DNA to
sperm which transfer the new DNA
during fertilization.
Gene gun:
 As described in Chapter 6.
This method involves:
 isolation of totipotent stem cells (stem
cells that can develop into any type of
specialized cell) from embryos
 the desired gene is inserted into these
cells
 Cells containing the desired DNA are
incorporated into the host's embryo.
Method of creating a clone
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The benefits of these animals to human
welfare can be grouped into areas:
 Agriculture
 Medicine
 Industry
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A) Breeding:
Traditional cross breeding have been used
for ages to create chickens, cows, pigs etc.
Farmers have always used selective
breeding to produce animals that exhibit
desired traits (e.g., increased milk
production, high growth rate).
Traditional breeding is a time-consuming,
difficult task.
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Researchers have now used gene transfer to
improve the productivity of livestock. Now it
is possible to develop traits in animals in a
shorter time and with more precision.
It also offers farmers an easy way to increase
yields.
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Scientists can improve the size of
livestock genetically.
Transgenic cows exist that produce
more milk or milk with less lactose or
cholesterol.
Transgenic cows have been used to
produce milk which are richer in
proteins and lower in fat.
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B) Quality
Herman, a transgenic bull carries a
human gene for Lactoferrin (gene
responsible for higher iron content)
Pigs and cattle that have more meat on
them.
Sheep that grow more wool.
Eggs can be made healthier with high
quality protein.
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Animals can be engineered to
be more nutritious, such as
the Belgian Bull Bull
Domesticated animals have
been used to produce
medically valuable proteins
in their milk
Goats have been engineered
to produce spider silk for
stronger materials.
C) Disease resistance
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Disease-resistant livestock is not a reality
just yet.
But there has been improvement in
disease reduction in animals.
The Foot- and- Mouth disease in England
in 2000 led to destruction of herds of
cattle, sheep and goat.
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Scientists are attempting to produce
disease-resistant animals, such as
influenza-resistant pigs, but a very
limited number of genes are currently
known to be responsible for
resistance to diseases in farm
animals.
Transgenic disease protection
promises a long term cost effective
method of battling animal diseases.
A)
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Xenotransplantation
Transplant organs may soon come from
transgenic animals.
Transgenic pigs may provide the
transplant organs needed to alleviate the
shortage of organs donor
..Xenotransplantation
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Xenotransplantation is hampered by a
pig protein that can cause donor
rejection but research is underway to
remove the pig protein and replace it
with a human protein.
Milk-producing transgenic animals are
especially useful for medicines.
Biotechnology has improved medicines
for animals, including vaccines used to
prevent animal diseases such as foot and
mouth, scours, brucellosis, shipping fever,
feline leukemia, rabies, and infections
affecting cultivated fish.
 There are new kits to diagnose the health
of livestock
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Blood Clotting factor in transgenic
•The Liver makes six blood clotting factors:
I (fibrinogen), II (Prothrombin), IV, V, VI, and
,
VII.
•Factor IV (calcium, Ca ionized and/or bound
calcium) also required for the coagulation of
blood in the process.
B) Nutritional supplements and
pharmaceuticals:
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Products such as insulin, growth
hormone, and blood anti-clotting factors
may soon be or have already been
obtained from the milk of transgenic
cows, sheep, or goats.
The first transgenic cow (Rosie )
produced human protein-enriched milk
at 2.4 grams per liter.
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This transgenic milk is a more
nutritionally balanced product than
natural milk and could be given to
babies or the elderly with special
nutritional or digestive needs.
A transgenic cow exists that produces
a substance to help human red cells
grow.
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Researchers at the University of Pennsylvania
have used gene therapy to shorten the time it
takes to breed large animals that produce
therapeutic proteins in their milk.
To get the goats to produce a specific protein:
radiation was used to kill a portion of male goat
germ cells and then a virus was used to insert
the gene of interest (therapeutic proteins) in
the remaining cells.
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Subsequently a predictable number of
offspring will carry the gene and produce the
desired protein in their milk (next figure)
Transgenic Goats to produce a
therapeautic protein
C) Human gene therapy:
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Human gene therapy involves adding
a normal copy of a gene (transgene)
to the genome of a person carrying
defective copies of the gene.
Finland produced a calf with a gene
that makes the substance that
promotes the growth of red cells in
humans.
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By extracting polymer strands from the milk
and weaving them into thread, the scientists
can create a light, tough, flexible material
that could be used in such applications as
military uniforms, medical microsutures,
and tennis racket strings.
Biosteel is an extraordinary new product
that may be soon used in bullet proof vests
and in suture silk for stitching wounds.
Animals have been used as “Bioreactors” to
produce proteins. Genes for desired proteins
are introduced via transgenics to the target
cells .
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The target cells are cloned and several such
cells are raised into adults.
These adults may produce milk or eggs
(due to the presence of introduced gene
rich in desired protein).
Toxicity-sensitive transgenic animals have
been produced for chemical safety testing.
Microorganisms have been engineered to
produce a wide variety of proteins, which
in turn can produce enzymes that can speed
up industrial chemical reactions.
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Transgenic animals have been used to
produce pharmaceutical protein: example
a human gene called AT III has been
transferred to goats.
Goats milk contain this protein that
prevents blood clotting (goats multiply
faster than cows)
“Hen bioreactor” eggs are used to enrich
protein by recombinant DNA technology.
A cloned pig in Denmark, The University of
Copenhagen, contains a gene responsible for
Alzheimer's disease
The cloned pigs were genetically modified to be
a model for Alzheimer's
Ethical concern is ever increasing as the
technology grows, including the issue of lab
animal welfare
 These ethical issues include questions such
as:
• Should there be universal protocols for
transgenesis?
• Should such protocols demand that only
the most promising research be
permitted?
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Is human welfare the only consideration?
What about the welfare of other life
forms?
Should scientists focus on in vitro
(cultured in a lab) transgenic methods
rather than, or before, using live animals
to alleviate animal suffering?
Two research groups have been given
permission to use hybrid human-animal
embryos in research
• Dr. Lyle Armstrong, who is based at the
North East England Stem Cell Institute
(NESCI) and the Stem Cell Biology
Laboratory Wolfson
Centre for Age-Related
Diseases, at King's
College London.
•
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Will transgenic animals radically change
the direction of evolution, which may
result in drastic consequences for nature
and humans alike?
Should patents be allowed on transgenic
animals, which may hamper the free
exchange of scientific research?
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Although there has been limited success in
cloning some animals, it's still seen as a viable
technology.
Ever since the announcement of the birth of
Dolly three years ago, additional sheep, cows,
goats, pigs and mice have been cloned.
So far, most cloned animals die just before or
after birth.
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There are still obvious problems as
evidenced from the numerous deaths
of cloned animals that occur just
before or after birth.
Cloning is a big first step. Genetic
manipulation of cloned animals is the
future direction of the cloning frontier.
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Cloning can produce genetically identical
laboratory animals which can be used as
models for human disease.
No live dog clones have yet been reported,
the company PerPETuate, Inc. (Connecticut)
is freezing tissue from family pets for the
future.
Cells could be harvested from early embryos
to provide cell and tissue replacement
without the hazards of transplantation
rejection.
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The cloning of human embryos for
reproductive purposes is illegal at this
time.
Yet it is still important to examine the
consequences and the likelihood of this
scenario.
The media may dream up and forecast
robotic cloned armies of Hitler; however,
identical twins illustrate that being
genetically identical does not remove
their humanness.
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At any rate, there have been significant
difficulties with cloning primates, including
an extremely low success rate and a high
number of abnormalities.
These results make it unacceptable to
attempt human cloning at this moment in
time.
Cloning has opened many doors that could
lead to remarkable medical advancements
but, as with all new technologies, it will be
accompanied by ethical and social
dilemmas.
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Today's successes will pave the road
to improving efficiencies and help
add to the basic understanding of our
cells.
Even Dolly's creator, Ian Wilmut, is
focusing less on sheep and more on
understanding the mechanism of
reprogramming our genetic
material!.
What are Stem cells?
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Keep update with political issues on stem cells
research including Christopher Reeves’
(Superman) idea of promoting stem cell
research.
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Stem cells can be used to grow any
organ.
Stem cells have the capacity to develop
into any type of cell in the body.
And therefore, they have the potential
to be used for almost anything, organ
transplants, a cure for Parkinson's etc.
Fetal stem cells, once harvested, cannot
become embryos!.
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When a woman's egg is fertilized, the egg
(or zygote) is totipotent -- it has the
capacity to turn into any type of cell in the
human body, including the placenta.
About four days after fertilization the
cells begin to specialize and form a
blastocyst, which is a hollow sphere of
cells with an inner cell mass in the center.
The outer layer of cells becomes the
placenta and other tissues necessary for
the survival of the fetus
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Inner cell mass - pluripotent, meaning they can
become any cell type in an organism
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The inner cell mass goes on to form
the fetus and eventually the baby. It is
these inner cells that are so incredible
because they go on to form all the
tissues in the human body.
If this inner cell mass was placed in a
woman's uterus, it would not develop
into a fetus and because of this some
people claim that this cannot be
considered an embryo
The controversy comes when the cells
are harvested.
Harvesting can be done by :
 obtaining cells from the embryos of
terminated pregnancies
 getting them from embryos from in
vitro fertilization clinics
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In 1993, President Clinton banned
federally funded research on stem cells
and now President Bush has promised
that he'll "not support research from
aborted fetuses."
The government's position reflects the
views by others who oppose stem cell
research. For example:
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Religious groups and some politicians
believe that it's unethical to harvest
these cells because they believe it
destroys the embryo.
One Kansas senator went as far as to
say that it's "Nazism," saying it's
"illegal, immoral, and unnecessary."3
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Some religious groups also believe that "you are
getting in the way of God's work.
Adult stem cells have limited potential and may
carry genetic mutations
Current status of Stem cell
Research in US V/s around
the globe
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http://www.animalbiotechnology.org/ani_bio.asp (List of
transgenic animals)
http://en.wikipedia.org/wiki/Human_cloning (Human
cloning)
http://www.gre.ac.uk/courses/under/sch/cls/biochem_bsc.htm
l (Cloning)
http://www.stemcells.ca/
http://en.wikipedia.org/wiki/Stem_cell
http://gslc.genetics.utah.edu/units/stemcells/
http://www.humancloning.org/dolly.htm (Dolly created)
http://news.bbc.co.uk/2/hi/science/nature/2764039.stm (Dolly
dies)