First Dolly and Now Millie
Dateline: 06/03/99
First Dolly and now Millie. Millie is a transgenic goat. Her milk contains a protein that could be extracted to make a drug for coronary bypass patients. The protein, called anti-thrombin III (AT III), is now in human clinical trials.
To produce a transgenic goat, researchers must follow several steps. First, the gene that produces AT III is sequenced, and scientists build a synthetic gene and make many copies.
The synthetic gene is then attached to the gene for casein, which acts as a promoter gene. This ensemble is then injected into a newly fertilized egg. During the first few critical cell divisions, the gene may become attached to the goat's DNA. If successful, the new gene is now a transgene which will become incorporated into all cells during subsequent divisions.
The embryo is then transferred to a surrogate mother. If the embryo turns out to be female, the AT III protein will be produced in her milk.
Based on this traditional method, approximately 50% of the offspring of an AT III goat would have the gene. Scientists then took this a step further. With the advent of refined cloning techniques in the past two years, researchers believed they could increase their efficiency rate by not only producing transgenic goats but also cloned transgenic goats.
Unlike Dolly, who was produced from an adult cell, the researchers used fibroblast cells from a 30-day old female goat fetus. After being grown in an incubator with media that contained the gene for AT III, the cells went through a process called electroporation. Electroporation allowed the cells to become porous and made it possible for the AT III gene to enter the cell's nucleus.
These cells were fused with an egg whose nucleus had been removed. The cloned embryos were then implanted into a surrogate. The final products were three identical female transgenic goats that produced the AT III protein.
What do you think? What are other potential uses for cloned transgenic organisms? Come over to the Biology Forum and share your thoughts, opinions, and feelings. Until next time...
For related information see:
Cloned Goat Produces Milk Worth Millions
News release from the LSU Agricultural Center.
Cloning
Information on human cloning, nuclear transfer, a cloning time line and more.
Biotechnology Net Links
Links and information pertaining to biotechnology.
