Transcript Chapter 7: Animal Biotechnology

Chapter 7: Animal Biotechnology
Introduction to Biotechnology
Fall 2008
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What are some of the animals…
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Mice
Rats
Zebrafish (3 month generation time, 200 progeny,
complete embryogenesis in 120 hrs)
Dogs (lungs and cardiovascular system)
Cats
Pigs (PPL Therapeutics- delete a gene which
causes hyperacute rejection of pig-to-human
organ transplantation)
Primates (HIV and AIDs research, geriatric
research)
Alternatives to Animal Models
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(figure 7.5) Cell culture devices
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Researchers use cell cultures and computergenerated models whenever possible, but this
doesn’t work for looking at an organ or entire
animal
Regulation of Animal Research
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The “Three Rs”
Reduce the number of higher species (cats,
dogs, primates) used
Replace animals with alternative models
whenever possible
Refine tests and experiments to ensure the
most humane conditions possible
Veterinary Medicine as Clinical
Trials
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Treatments for humans may also be useful for
treatments with animals (e.g. the BRCA1 gene
found in 65% of human breast tumors is similar
to the BRCA1 gene in dogs)
Hyperthermia + radiation = more effective at
killing tumors
Stimulation of cytokines for curing skin cancers
Bioengineering Mosquitoes to
Prevent Malaria
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Cloned in a gene that prevents the parasite
from traversing the midgut; blocking the
continuation of its life cycle
Developed an antibody that prevents the
parasite from entering the mosquito’s
salivary gland
Clones
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Start with Embryo Twinning (splitting embryos
in half)
Cloning (figure 7.7)
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Creating Dolly
Limits to Cloning: The donor cell must come from a
living organism
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An organism is also shaped by its environment
The success rate for cloning is very low
Clones may be old before their time
The future of cloning: preservation of endangered
animals, studying the effect of drugs etc on
duplicates, improve agricultural production
Transgenic Animals
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Retrovirus-mediated transgenesis
Pronuclear microinjection (figure 7.8)
Embronyic stem cell method
Sperm-mediated transfer
Improving Agricultural Products
with Transgenics
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Faster growth rates or leaner growth
patterns (improve the product), more
product
Increase nutritional content-lactoferrin
Turning the animals into efficient grazers
Transfer antimicrobial genes to farm
animals
Knock-outs: A Special Case of Transgenesis
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A specific gene is disrupted or removed such that it is
not expressed (Figure 7.11)
Procedure: DNA is modified, it is added to embryonic
stem cells, where it undergoes homologous
recombination. The modified ES cells are then
introduced into normal embryo. The embryo is
implanted in an incubator mother. The offspring is a
chimera. It may take several generations of
crossbreeding are required to produce animals that are
complete knock-outs.
Breast cancer mouse
Transgenic Animals as
Bioreactors
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Biosteel otherwise known as spider silk,
cloned into goat milk (“silkmilk” goats)
Goats reproduce faster than cows and are
cheaper than cows
Hens also make good bioreactors in that
they are cheap and a lot of eggs are
produced at one time
Producing Human Antibodies in Animals
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1980’s Concept of the “magic bullet”
Figure 7.12: Production of Mabs
Used to treat cancer, heart disease, and
transplant rejection
HUMANIZED monoclonal antibodies
were developed to prevent the human antimouse antibody (HAMA) response