Chapter 7

Animal Biotechnology

Animals in Research

B1

B4

B2

B3

Animals in Research

Animals in Research

Animation ofDrug Development Process

Animal Models• 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)

Animals in Research

Alternatives to Animal Models• Cell culture devices

• Researchers use cell cultures and computer-generated models whenever possible, but this doesn’t work for looking at an organ or entire animal

Animals in Research

Regulation of Animal Research• 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

Animals in Research

Veterinary Medicine as Clinical Trials• 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

Animals in Research

Bioengineering Mosquitoes to Prevent Malaria• 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

Animals in Research

Clones

Cloning• Creating Dolly• Limits to Cloning: The donor cell

must come from a living organism• 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

Retrovirus-mediated transgenesis

Pronuclear microinjectionEmbronyic stem cell methodSperm-mediated transfer

Improving Agricultural Products with Transgenics• 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

Transgenic Animals

Transgenic Animals as Bioreactors• 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

Transgenic Animals

Knock-outs: A Special Case of Transgenesis• A specific gene is disrupted or

removed such that it is not expressed

• 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

Producing Human Antibodies in Animals

Production of Monoclonal antibodies (Mabs)• Used to treat cancer,

heart disease, and transplant rejection

• HUMANIZED monoclonal antibodies were developed to prevent the human anti-mouse antibody (HAMA) response