Why is model organism research important?
Begun in 1990, the U.S. Human Genome Project is a 15-year
effort coordinated by the U.S. Department of
Energy and the
National Institutes of Health to
Identify all the estimated 80,000 genes in
human DNA,
Determine the sequences of the 3 billion
chemical
bases that make up human DNA, store this
information
in databases, and develop tools for data
analysis.
To help achieve these goals, researchers also
are studying
the genetic makeup of several nonhuman
organisms. These
include those species:
-
Human
3000 million bases (60,000 to 80,000
genes)
- Mouse
3000 million bases (50,000 to 100,000
genes)
- Drosophila (fruit fly)
165 million bases (15,000 to 25,000
genes)
- Nematode (roundworm)
100 million bases (11,800 to 13,800
genes)
- Yeast (fungus)
14 million bases (8355 to 8947 genes)
- E. coli (bacteria)
4.67 million bases (3237 genes)
- H. influenzae (bacteria)
1.8 million bases
- M. genitalium (bacteria)
0.58 million bases
Model organisms offer a cost-effective way to follow the inheritance of
genes (that are very similar to human genes) through many
generations in a
relatively short time. Some model organisms being studied in
HGP are the
bacterium Escherichia coli, yeast Saccharomyces cerevisae,
roundworm
Caenorhabditis elegans, fruit fly Drosophila melanogaster,
and laboratory
mouse. Additionally, HGP spinoffs have led to genetic
analysis of other
environmentally and industrially important organisms in the
United States
and abroad.
Example:
Of Mice and Humans: The Value of Comparative
Analyses
A remaining challenge is to recognize and
discriminate all
the functional constituents of a gene,
particularly regulatory
components not represented within cDNAs, and to
predict
what each gene may actually do in human biology.
Comparing human and mouse sequences is an
exceptionally
powerful way to identify homologous genes and
regulatory
elements that have been substantially conserved
during
evolution.
Researchers led by Leroy Hood (University of
Washington,
Seattle) have analyzed more than one million
bases of
sequence from T-cell receptor (TCR) chromosome
regions
of both human and mouse genomes. Many subtle
functional
elements can be recognized only by comparing
human and
mouse sequences. TCRs play a major role in
immunity and
autoimmune disease, and insights into their
mechanisms
may one day help treat or even prevent such
diseases as
arthritis, diabetes, and multiple sclerosis
(possibly even
AIDS).
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