Transcript Altering the Path of Evolution

Altering the Path of
Evolution
with the use of
Current Reproductive
Technologies and Genetic
Engineering
“Biotechnology is an area of applied science that has
grown at an astonishing rate over the last two decades. It
promises to have a profound effect on our use of other
organisms, our impact on the environment, our health,
and even on the nature and direction of our own
evolution.”
Allan, R. (2000) Year 12 Biology 2001 – Student Resource and
Activity Manual BIOZONE International Ltd.
Now and the Future
•Today reproductive biotechnology and genetic engineering is
advancing at a revolutionary pace. This speed makes it difficult
for us to always see the bigger picture involving not only all of
humanity, but all living things and their physical environments. All
too often the focus is on immediate gains to a limited number of
individuals.
•This PowerPoint will allow us to begin to understand how the
application of biological theory and technology interacts within
the world in which we live.
•Biologists of the present and future need to be more intelligent,
responsible, analytical and forward thinking than ever before in
order for the biological world to flourish, rather than suffer the
consequences of poor biological decisions and actions.
Selective Breeding
•For as long as humans have been agriculturists they have
selected for favourable characteristics in the plants and animals
by breeding desirable traits or characteristics together in similar
varieties of organisms.
•In doing so, farmers, breeders and scientists have influenced
the natural gene pool by changing it to suit their needs.
•Once a favourable organism has been bred for a particular
purpose, it is reproduced continually. On the reverse hand,
undesirable organisms are not bred. This begins to sound like a
little like natural selection. Although it is selection, it is not
‘natural’. Actions such as these place focus on only a few types
of organisms and their genetic characteristics, and therefore
reduce the biodiversity in a community. Let’s take a look...
Artificial Insemination
•Artificial insemination (AI) is the injection of male semen into
either the vagina or cervix of a female without the act of sexual
intercourse
•The first record of AI dates back to an Arab chieftan in the
1320s who used this technique to produce superior horses.
•Today most farmed animals are bred by AI.
•Desired characteristics include: cattle with more beef, higher
milk production, milk with more butter fat; or sheep with finer
wool; or pigs with less fat.
•Champion sheep, pigs, bulls or horses can have their sperm
collected, frozen and then flown anywhere in the world in order
to provided a desirable mate for a desirable female living in
another paddock in another part of the world.
Artificial Insemination
http://www.equiworld.net/uk/horsecare/artificialinsemination/artificialinsemination.htm
An advertisement for
a sperm transport
container
Semen is collected from the
stallion before he is able to
penetrate the filly.
http://www.equitainer.com/
Artificial Insemination
•Overuse of the sperm from one male can reduce genetic
diversity in the population. This becomes a problem if;
• the male is later found to carry a harmful recessive or late
onset disorder that has now been spread throughout a large
population. In case this should happen it is important to
maintain detailed pedigrees in order to trace related animals.
•there is an environmental (physical or chemical) change and
there is no genetic variety in order to allow the population to
adapt effectively over time.
•Over use of a small number of breeding animals results in many
consanguineous matings. When related individuals that are
heterozygous for undesirable recessive traits breed, there is a
25% chance of that trait expressing itself in the phenotype.
Artificial Pollination
•Artificial pollination is the removal of the male pollen from
one flower which is then deposited on the female stigma of
another flower.
•As with AI, artificial pollination aims to breed organisms with
the most desirable characteristics.
•Mendel used artificial pollination when conducting his pea
experiments.
•Desired characteristics include higher yield, larger fruit,
resistance to frost, resistance to disease.
Artificial Pollination
http://pro.corbis.com/search/searchFrame.asp
Artificial Pollination
•Overuse of artificial pollination can reduce genetic diversity in
the population. This becomes a problem if:
•there is an environmental (physical or chemical) change and
there is no genetic variety in order to allow the population to
adapt effectively over time.
•as the plants in use have similar genetic characteristics they
are particularly susceptible to any disease they may come in
contact with.
•In the early to mid1800s the Irish had so little land they all
farmed potato – a crop with a high yield. When a few plants
became infected with a fungus it wasn’t long before all crops
were infected. As the Irish farmer had planted nothing else, mass
starvation (over 1 of the 3 million inhabitants) was inevitable.
Cloning
•A clone is an organism with an identical genotype to another. Cloning can
produce an organism with the identical genetic make-up to the parent.
•Cloning occurs naturally in all organisms that reproduce asexually. When
cells divide by mitosis they are cloning themselves.
•Humans have been cloning plants for thousands of years by simply taking
cuttings from one plant and growing a new plant from it.
•Bacteria mostly reproduce asexually therefore cloning themselves. Some
animals also clone themselves asexually. Examples include: budding in
jellyfish and coral; fragmentation in some worms; and parthenogenesis – the
‘virgin birth’ in bees. (see ‘Asexual Reproduction’ PPT in Biology folder)
•Identical (maternal) twins are clones, but they are produced from 2 parents,
neither of whom is their clone.
•Cloning of animals (that usually reproduce sexually) from one generation to
the next is extremely difficult and has only recently been achieved due to the
advance in reproductive technology.
1. Cloning plants – using cells from a
singe parent
Cells taken from root
tip where mitosis is
actively taking place
Root cells are cultured
(grown) in a nutrient
media that provides
the cells with
everything they needin
order to grow and
reproduce
Cells start to
form identical
new plants
Cells are
isolated
Offspring
are
clones of
parent
2. Cloning Animal Cells– Using undifferentiated
pluripotent stem cells from a single blastocyst created
by two parents
•After the sperm fertilizes the oocyte the single celled embryo undergoes
cell division by mitosis. After several hours a blastocyst (bundle of cells)
forms. It is possible to remove and isolate the undifferentiated stem cells
from the centre of the blastocyst without destroying them or their function.
•Each isolated undifferentiated pluripotent stem cell will continue to divide
into a normal organism – each one genetically identical.
•If the cells are separated too late then they have already begun to
differentiate – that is, take on different roles within the function of the whole
organism. The cells will not function properly in isolation once differentiated.
•This form of cloning has been used in agriculture.
•Let’s have a look at how this works…
2. Cloning Animal Cells– Using undifferentiated
pluripotent stem cells from a single blastocyst created
by both parents
Fertilization
Cell divides
by mitosis
into 2 cells
Embryo
forms
blastocyst
Mitosis
continues - 4
cell morula, etc
Central blastocyst
cells are
undifferentiated
Central
blastocyst
cells are
dissociated
Cloned identical ‘twins’ are cultured in media
and implanted as embryos into females of the
same species. Note: they are clones of each
other, not of either of their parents.
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
•When cloning a whole organism, instead of fusing two gametes (1N + 1N= 2
N) scientists take the nucleus of a somatic cell (2N) and place it in an oocyte
that has had the nucleus removed (0N). This is known as somatic cell
nuclear transfer (SCNT).
•The somatic cell is differentiated and it has only been in recent years that
scientists have been able to reverse differentiation. Usually, skin cells only
know how to act as skin cells, muscle cells are programmed to be muscle
cells, and so on. Scientists have had to convince the skin cell or muscle cell
to forget its role in order to become undifferentiated so that it can develop
into a whole new organism composed of a variety of different cell types.
•For approximately every hundred attempts to clone a mammal, only 1 is
successful. The embryos suffer an enormous variety of structural, behavioral
and/or chemical abnormalities.
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
•To this day it is not clear what makes this complex process a success or
failure. The method for cloning each organism is slightly different and the
whole procedure is still highly experimental.
•Ian Wilmut and team at the Roslin Institute in Scotland reported the first
cloned mammal in 1996.
•Since then scientists have been able to clone a variety of mammals
including cows, cats, rats, rabbits, pigs, horses, oxes and goats.
•Serious attempts at cloning whole organisms by SCNT began about 40
years ago. John Gurdon had some success cloning frogs in 1970. The
cloned frog developed only to the tadpole stage before it died, therefore
never becoming an adult frog.
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
Gurdon’s Experiments from the 1970s
Nucleus
removed
from
oocyte of
frog A
http://science.howstuffworks.com
Tadpole
cloned from
frog B – dies
before
developing
into adult frog
Nucleus
taken out of
somatic cell
of frog B and
fused with
enucleated
oocyte from
frog A
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
http://science.howstuffworks.com
Dolly with her
surrogate
mother
•227 nuclear
transfers led to
29 embryos
implanted in 13
ewes of which 1
succeeded
•At two years of age Dolly gave birth
after a normal conception & pregnancy
•RIP. Dolly died in 2003 due to a lung
infection. She was only 6 years old –
half the age of the average sheep.
•Is this ‘experiment’ reliable and valid?
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
Cloning to save endangered species?
“On January 8, 2001, scientists at
Advanced Cell Technology, Inc.,
announced the birth of the first clone of
an endangered animal, a baby bull gaur
(a large wild ox from India and southeast
Asia) named Noah. Noah died of an
infection unrelated to the procedure. “
•How can scientists guarantee that
Noah’s immune system was not
compromised by his being a clone? His
unusual genetics may have affected
the function of immunological proteins
reducing his chance of survival.
•Is this worthwhile & ethical?
Courtesy of Advanced cell technology at http://science.howstuffworks.com/cloning.htm
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
Cloning to replace a family pet?
•Cloning solely for ‘emotional’
reasons – is it worthwhile and
ethical?
Cloned cat
Clone (CC)
•Are owners really ‘replacing’ a
loved pet?
•Should money be spent on
cloning for these reasons?
Surrogate mother with CC
http://www.mun.ca/biology/scarr/Cloned_Cat.htm
•We also need to consider the
sensationalist press regarding
the cloning of humans…
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
Cloning humans?
“The 6th cloned baby was born on Thursday the 5th of February [2003]
in Australia.The Clonaid team, after 20 more implantations, had 8
successful pregnancies. The first one of this new series is now born,
perfectly healthy and his health is documented today by a pediatrician in
Sydney.The seven other babies are expected these two coming weeks.
An update will be made for each birth on this website. nb: The cloned
child born in Australia was not conceived within Australia and therefore
adheres to Australian cloning laws.”
•Clonaid – fact or fallacy?
•Australian experts (such as Alan Trounson) say ‘fallacy’.
4. Therapeutic Cloning of animal
undifferentiated embryonic stem (ES) cells
derived from SCNT for tissue repair
The Australian Academy of Science (1999) had this to
say on Human Cloning:
“Reproductive cloning to produce human fetuses is
unethical and unsafe and should be prohibited.
However, human cells, whether derived from cloning
techniques or from embryonic stem cells should not
be precluded from use in approved research activities
in cellular and developmental biology.”
4. Therapeutic Cloning of animal undifferentiated ES
cells derived from SCNT for tissue repair
•Therapeutic cloning follows the same steps as reproductive cloning until the
point where the embryonic stem cell is implanted into a surrogate female.
•Therapeutic cloning means that an oocyte is enucleated, and fused with the
nucleus from a somatic cell. This undifferentiated embryonic stem cell is then
cloned by being allowed to undergo mitosis. Before the cells start to
differentiate and program themselves to specific roles, scientists can grow
them into the cell types they desire, such as nerve cells, skin cells or
myocardial (heart muscle) cells.
•In humans, embryonic stem cells are cultured in the laboratory and grown
into specialised tissue. such as skin cells for grafting. Professor Alan
Trounson from Melbourne is Australia’s leading stem cell researcher.
•Skin cells can be grown and used for skin grafts, nerve cells used to treat
neurological disorders such as Parkinsons or Altzeimers, and miocardial cells
used to treat patients with heart muscle disorders.
•The grafted tissue is immunologically compatible as it is the patients own.
4. Therapeutic Cloning of animal undifferentiated ES
cells derived from SCNT for tissue repair
http://science.howstuffworks.com
Embryonic Stem
cells cultured in a
petrie dish
Reproductive
cloning
Eg. Stem cells
used to grow
skin cells for
grafting
•Advanced cell technology in
2001 (USA) have already
reported human cloning for
therapeutic reasons.
•Is therapeutic cloning ethical?
•Is the embryo alive?
•Does the embryo have a right to
survive?
Cloning – arguments for
•More efficient and cheaper ways to mass produce good quality
food and clothing supplies
•Endangered species could be cloned to increase their population.
•Extinct species could be brought back to life.
•Human body parts can be harvested and cloned by therapeutic
cloning.
Cloning – arguments against
•Cloning will reduce differences in the genetic make-up within the different
species so uniqueness and individuality in individuals would disappear.
•If all species have identical genetic material, a disease could wipe out the
entire population of the particular species.
•Cloning certain animals will over produce them and then under produce
others reducing biodiversity.
•Corporate greed will take over as companies try to market organisms
and/or genes
•Nuclear transfer has a high failure rate.
•We are taking nature into our own hands i.e. we are trying to play God.
•If the technology falls into the wrong hands the effect could be disastrous.
Extremist groups could make the so-called “supper race”
•Cloning body parts actually creates something alive, so do these body
parts have rights?
Cloning – more contentious
reasons (mostly human cloning)
•Offspring can be born without a father.
•We could bring back relatives, loved ones and famous people.
•Parents who can’t have children physically can clone to produce their own
offspring.
•Parents can ‘replace’ a dead child (are they really replacing them?)
•Families with diseases could clone healthiest parent
Transgenic Species
•A transgenic organism is one that has a gene from another organism
inserted into its own genetic material. This is also known as DNA
recombination.
•If one organism doesn’t have a particular characteristic then scientists find
and isolate a gene from another organism that does code for that
characteristic and then insert it into the original organism.
•Genes can be added by:
•Micro-injecting into embryonic stem cells
•Using electrical pulses (electroporation)
•Injecting using a gene gun
•Transferring using a bacteria or virus
Transgenic Species – using bacteria
Bacterial
Chromosome
Bacterial plasmid
(enlarged)
Section of DNA from
source is cut out
using restriction
enzymes
The bacterial plasmid is also
cut with the restriction enzyme
and the source DNA is inserted
Host organism is infected with the
bacteria whose DNA incorporates
into the hosts chromosome
Transgenic Species
•For example a bacteria called Bacillus thuringiensis (Bt) can make a
protein that is toxic to insects. Scientists have managed to take the gene
that codes for this protein – the Bt gene - and insert it into crops such as
wheat and soy. The crops are then immune to the insects that might eat it.
•GM foods examples: herbicide resistant corn, antifreeze from cold-water
fish into strawberries, vaccine in bananas, tomatoes with a longer shelf life.
•In mammals, SCNT derived ES cells can be genetically altered by DNA
recombination (in this case inserting a novel gene) and then transplanted
into a surrogate mother. Transgenic sheep have been produced that
secrete a protein (antitrypsin) in their milk that helps treat human lung
disease.
•Other milk producing mammals can produce factor VIII to help
hemophiliac’s blood clot and insulin for diabetes sufferers.
•Transgenic mice (rats, rabbits) have been genetically engineered with
human diseases in order to help scientists find a cure for that disease.
Transgenic Species – arguments against
•Genetically engineered organisms might hybridize with natural organisms and
produce new diseases, or resistance to certain drugs
•Bacteria or viruses used to transfer genes from one organism to another could
become harmful and spread throughout the population
•Eating GE food could affect health – ie allergies sufferers, animals virus passed on
to humans
•Religious diets
•Endangered insects could eat Bt crops and die
•The health of the transgenic organism might be at risk (transgenic pigs have arthritis)
•Eugenics movements might resurface
•Corporate greed will take over as companies try to market organisms and/or genes.
Terminator seed – disease resistant and produce bumper crops but cannot be
harvested. Monsanto have the patent.
•Transgenes might ‘escape’ into native populations and disrupt the ecosystem
•In the long term transgenic organisms will be cloned, reducing genetic variation
Transgenic Species – arguments for
•Improve livestock and agricultural products for human use. This
includes improving productivity, quality and ability to live in extreme
conditions.
•Improve the resistance of plants and animals to diseases or
chemicals such as herbicides .
•Organisms that can genetically fight off predators means there is
less harmful spraying of poisonous chemicals into the environment.
•Disease and human defects could be reduced.
•New products can be developed, such as medicines and vaccines.
•People living in developing countries can be given food with
enhanced nutrient content to reduce disease due to deficiencies.
•Vaccines can be eaten thus reducing the cost of production.
•In the short term genetic diversity is increased.
Maintaining Biodiversity - recap
•Over production of one organism reduces the number of different
genes in a population which can create a problem if the environmental
conditions change either physically or chemically.
•Over production of one species of potato in Ireland led to reduced
biodiversity with deadly consequences for the population (in South
America they had hundreds of species).
•The healthy function of natural ecosystems relies on biodiversity.
•Research on different varieties of plants can provide new medicines.
•Seed banks have now been set up in order to safeguard different
varieties of plants.
•Habitat conservation to stop the destruction of diverse species.
The End?
“This is not the end. It is not
even the beginning of the
end. But it is, perhaps, the
end of the beginning.”
Winston Churchill
References
•Allan, R. (2000) Year 12 Biology 2001 – Student Resource and Activity Manual BIOZONE,
International Ltd.
•Aubusson, P. and Kennedy, E. (2000) Biology in Context. The Spectrum of Life Oxford University
Press, Melbourne, Australia.
•Australian Academy of Science (1999) Therapeutic Cloning for Tissue Repair
•Biever, C. [2003] New Scientist Online: UN postpones global human cloning ban Retrieved from
site http://www.newscientist.com/hottopics/cloning/cloning.jsp?id=ns99994359 April 2004.
•Board of Studies (2002) STAGE 6 SYLLABUS Biology Board of Studies, NSW, Australia.
•Clonaide;Pioneers in Human Cloning [no date] Retrieved from the site
http://www.clonaid.com/news.php April 2004.,
•Equiworld magazine [no date] Retrieved from the site
http://www.equiworld.net/uk/horsecare/artificialinsemination/artificialinsemination.htm April
2004.
•Freudenrich, C [no date] How Cloning Works Retrieved from site
http://science.howstuffworks.com/cloning.htm April 2004.
•Hamilton Research (2003) The Equicontainer retrieved from the site
http://www.equitainer.com/ April 2004.
References
•Humphreys, Kerri (2003) Biology. Blueprint of Life. Science Press, Australia.
•Issues in Society: Cloning (1999) Ed. Justin Healey, The Spinney Press, Australia.
•Kinnear, J and Martin, M (2001) Biology 2 HSC Course: Jacaranda HSC Science John Wiley &
Sons, Australia, Ltd.
•Mudie, K. et.al. (2000) Heinemann Biology Malcom Parsons, National Library of Australia,
Australia.
•Schwartz, Shaul (2004) Corbis. Retrieved from the site
http://pro.corbis.com/search/searchFrame.asp April 2004.
•Sneddon, R (2002) DNA & GENETIC ENGINEERING Reed Educational and Professional
Publishing Ltd Heinemann, Oxford, UK.
•[author not known] [no date] Rainbow and cc, the world’s first cloned cat Retrieved from site
http://www.mun.ca/biology/scarr/Cloned_Cat.htm April 2004.
•Wilmut, I. et.al. (2003) Human Cloning: Can it be made safe? Nature Reviews.Genetics. Vol 4
November.
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
TM
CLONAID , the first human cloning company in the world,
was founded in February 1997, by RAËL and a group of
investors who created the Valiant Venture Ltd Corporation
based in the Bahamas. In the first couple of years CLONAID™
has already received enormous media coverage. However, due
to the pressure mounted on the Bahamas government by
French journalists, Valiant Venture Ltd was cancelled as
government representatives were thinking the laboratories
would be established on the Bahamas Island. Meanwhile, the
list of serious potential customers had grown to more than
250 people! Therefore, during the year 2000, Rael decided to
hand over the CLONAID™ project to Dr. Brigitte Boisselier, a
Raelian Bishop, in order for her to start working on actually
cloning the first human being with a team of well-trained
scientists. Dr. Boisselier has PhD degrees in physical and
biomolecular chemistry. In her last job she was a marketing
director for a large chemical company in France.
http://www.clonaid.com/news.php
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear Transfer (SCNT)
CLONAID™: New cloning services
• If you are a sterile couple with no more hope of having the child you
dream of,
• If you are a homosexual couple with a profound desire to have a child
carrying your own genes,
• If you are infected with the HIV virus and you would like to have a child
carrying your own genes without passing on the virus to the baby nor to
your partner,
• If you just lost a beloved family member and would like to see an
identical twin of him/her live again,
• If you want to be cloned, whatever your reasons may be, then
CLONAID™ has the right program for you.
•Are these ‘reasons’ for cloning humans justifiable?
•The need for governments to have specific laws to keep pace with
advancing biotechnology – particular human cloning - is essential.
http://www.newscientist.com/hottopics/cloning/cloning.jsp?id=ns99994359
3. Reproductive cloning of a single animal from
differentiated somatic cells using Somatic Cell
Nuclear
Transfer
(SCNT)
Nuclear
transfer
UN postpones global human cloning ban
Already banned in
30 countries
“The United Nations' General Assembly in New York narrowly voted to postpone
any ban on human cloning until 2005 on Thursday, leading many scientists around
the world to breathe a sigh of relief.
Reproductive cloning - creating babies - is regarded by virtually everyone as
dangerous and unethical. But opinion is split on therapeutic cloning - the use of
cloned embryos to harvest stem cells for medical use. Supporters say the
approach offers unrivalled promise for the treatment of many diseases, such as
Parkinson's and diabetes. "No decision is better than the wrong decision," says
Bob Ward, spokesperson for the UK's premier scientific association, the Royal
Society. Ian Wilmut, who led the cloning of the first adult mammal, Dolly the sheep,
agrees: "I think it is a lesser evil to have this solution than to have a complete
ban…I am convinced that therapeutic cloning offers health opportunities that you
could not attain in any other way,"