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Genetically Modified Cows

Biotechnology Project - Yemin Shou - SBI4UR - Walker


on 3 December 2012

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Transcript of Genetically Modified Cows

Genetically Modified Cows Producing Hypoallergenic Milk Did you know? 2-3% of infants are allergic to dairy milk (used in baby formulas) in their first year of life
Allergic reactions can cause a variety of symptoms
Stomach cramps
Caused by the protein beta-lactoglobulin (BLG) found in cow milk, but not present in human milk By: Yemin Shou The Solution New Zealand researchers have genetically modified a cow to produce milk that does not contain the BLG protein
This milk can also be healthier than normal milk - higher levels of protein casein was the technique used to block the production of the BLG protein by silencing the gene that codes for this protein. Let's take a closer look inside the cow... RNA interference (RNAi) How does this work? What is RNAi? RNAi is a natural process present in many eukaryotic organisms
Occurs in cells to silence the activity of specific genes The presence of unnatural double-stranded RNA (dsRNA) triggers RNAi to occur
Believed to serve as an antiviral defense mechanism
When viral RNA replicates, it temporarily becomes double-stranded, triggering RNAi Let's take a look at the process of RNAi inside a cell... 1. dsRNA enters the cell through a virus or another source 2. Enzyme Dicer detects the dsRNA and immediately cuts it into 22 nucleotide long segments called small interfering RNA (siRNA) which are still double-stranded dsRNA siRNA dicer siRNA RISC 3. Protein RNA-Induced Silencing Complex (RISC) attaches to the siRNA 4. The RISC unwinds the siRNA and the antisense strand (strand complimentary to original gene on RNA) stays attached to the RISC to form a RISC/RNA complex RISC/RNA Complex 5. The RISC/RNA complex then looks for mRNA that has matching sequences as the one on the complex 6. When it finds a long piece of RNA that contains the matching sequences on the complex, the RISC/RNA complex binds to the new target RNA and cuts it mRNA mRNA RISC/RNA Complex mRNA The cut mRNA is now no longer usable in the production of a protein, thus the gene is silenced and production no longer occurs. The Biotechnology RNAi naturally occurs as defense against viral infections by blocking the replication of the virus
This technique can be applied to silence specific genes in mammals and other living organisms by creating micro RNA (miRNA) to target a specific gene
This miRNA is then injected into the cells where the process of RNAi will be triggered and the gene will become silenced
Cows were genetically modified in this way to block the production of beta-lactoglobulin (BLG) protein Daisy the Genetically Modified Calf Scientists started to test the technique of blocking BLG on mice (who were genetically engineered to produce BLG) before cloning a cow because it is cheaper
When they found that it had worked, they felt comfortable trying it on cows
Daisy is a cow who was born out of 57 cloned embryos which expressed the two miRNAs which would block BLG
She was born without a tail, a defect linked to the cloning
Daisy was hormonally induced to lactate and the analysis of the milk showed very little levels of BLG
However, a few years are needed until Daisy can naturally lactate and the composition of the natural milk must be analyzed as well
Actual commercial use of the hypoallergenic milk will be a long way off because the effects of the new composition of the milk must be investigated, and many more tests must be performed Other Applications of RNAi RNAi was discovered just over a decade ago
It is a huge step in the possibilities of genetic modification
The discovery of RNAi brought many new ideas for medicine applications
RNAi could halt cancer because it can silence the gene responsible
Many new treatments for diseases will also rise through RNAi to silence the gene (Huntington's, Hepatitis C)
Investigators are working intensely to fully understand the effects of RNAi for use in medical therapies Ethical Dilemma - Animals For the most part, the ethical dilemma in producing genetically modified livestock is regarding the treatment of the animals
The consequences that may arise from new knowledge and experiments with animals are not always known
Testing and creating genetically modified products can lead to suffering of the animals tested on
Animals can be born with deformalities, brain tumors, brain defects, and deformed limbs
Genetic experiments gone wrong could cause diseases in humans On the other hand, performing experiments and researching with animals helps provide humans with more ways to improve biotechnology and make advancements in medicine
Because the RNAi process was tested on Daisy the calf, advancements in medicine and application of this process improved
Less animal testing can also make the product less safe for human usage Ethical Dilemma - Humans Career A possible career involved in developing genetically modified livestock and experimenting for new ideas is to become a biotechnology researcher
It involves the use of living organisms or cell processes to make useful products
The education requires a Ph.D. to be given responsibility to do creative work
Some individuals can advance with just a bachelor's degree but they must work as a research assistant for one or two years before pursuing an advanced degree. The Result The level of BLG in the milk was reduced by 96%
Resulted in different composition of milk
Higher protein casein levels
Higher calcium levels
Improved cheese yields
Would be much better alternative to industry processes to remove the BLG protein from the milk, often resulting in a bitter taste Possibly in the near future... Hypoallergenic! Hypoallergenic! Hypoallergenic! Hi!
My name is Daisy. Thank you for learning about me!
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