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The Science of Transgenics
Our bodies are made up of some 30,000 genes, many of
which are involved in diseases such as hypertension,
diabetes, cancer, and other illnesses. To study how
these genes work, scientists often introduce the gene
they are studying into an animal model through a process
called transgenics. For example, researchers examining
the biological causes of breast cancer may engineer
a mouse model to contain a gene linked to breast cancer.
By studying the gene in animals, scientists can gain
information about human disease that can be used to
develop new therapies to treat the illness.
Scientists use a number of different techniques to
create transgenic animals, but the most common is a
process called microinjection. Scientists isolate
the gene they want to study, inject hundreds of copies
of it into a fertilized egg, and transplant that egg
into a surrogate animal. Some of the animal offspring
will contain the foreign gene (also called a transgene)
and will be able to pass it on to the next generation.
These animals are called transgenic. Genes can be added
to an animal with microinjection, but they cannot be
deleted with this technique.
When scientists use microinjection, the gene is inserted
randomly into the animal's genome. Sometimes, however,
researchers want to see how a particular gene behaves
in a particular tissue. For this type of study, researchers
often develop transgenic animals using a process called
embryonic stem cell transfer, or the gene-targeted transgenic
approach. Scientists delete or substitute a specific
gene in embryonic stem cells in a Petri dish and inject
the modified stem cells into a clump of cells called
a blastocyst, which is derived from a fertilized egg.
The blastocyst is implanted into a surrogate animal;
some of the animal's offspring will carry the gene the
scientists want to study.
Last updated January 10, 2005. |
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