June 01, 2003
"Community, Identity, Stability," describe the Brave New World
conceived by Aldous Huxley in 1932; today we stand on the brink of
a brave new world characterized by the possibilities contained
inside a double helix.
Recent technological advances in human and animal genetics have
lead to sequencing the human genome, mapping the severe acute
respiratory syndrome (SARS) virus and in the near future, the
release of the completed bovine genetic code.
Dr. James E. Womack, a distinguished professor at the College of
Veterinary Medicine, Texas A&M University has spent 22 years in
cattle genetics analyzing comparative maps that allow him to use
the human genome as a rough key to unlocking the cattle code.
"One of the great things of working with a species like cattle
is that we have the human model to follow," Womack said. "We've had
to develop a few new technologies specific to cattle, particularly
in the statistical analysis and the breeding structure of families
but as far as laboratory bench technologies, we've pretty much
followed the lead of human genetics."
When Womack began studying the bovine genome he was actively
comparing the human and mouse genomes and trying to understand the
evolutionary events that might have made our genomes different. In
1982, he decided it was necessary to add a third group to the
equation that didn't consist of primates or rodents, and being from
Texas, it was logical to choose the bovine.
"Cattle have been difficult to map because like humans, they
breed slow and do not produce large numbers of offspring, however,
the technologies developed for humans were generally applicable to
cattle as well," Womack said.
Genetic mapping is an attempt to find mileposts along the genome
of a particular organism. The genome is the total genetic material
contained in every cell of a species and the DNA that makes up the
genome serves as coding for a particular animal. Determining the
exact sequence of the chemicals contained in DNA involves a string
of 3 billion figures.
"Genetic sequencing is the ultimate map; knowing every inch of
the road," Womack said. "Mapping as we currently do it in cattle is
not finding every inch of the road and defining it, but finding
mile posts along the way and the functional elements that actually
code for something like disease resistance."
In comparative mapping, Womack studies, for example, chromosome
1 on the human genome and by comparison, identifies what genes on
chromosome 1 match up in the bovine. This may mean that chromosome
1 in the human matches chromosome 3 in cattle. By using this
method, if a gene coding for human disease resistance is found on
chromosome 1 then Womack can look at the comparative map and
hypothesize that a similar gene may be found on chromosome 3 in
cattle. This comparison may help to develop a better understanding
of how viruses and bacteria affect cattle.
Instead of sequencing the host species, some researchers focus
on the virus or bacteria affecting that group. Sequencing a viral
genome, like SARS, is typically easier than an entire species
because it is very small with just a few thousand bases as oppose
to billions. However, viruses have the unique ability to rapidly
evolve into resistant stages making it difficult to develop an
effective antibiotic treatment. In the case of the SARS virus,
Womack believes a new strain of a pre-existing virus genetically
changed into a more virulent form. Knowing more about the human
genome and the virus sequence may help slow the spread of this and
"Understanding infection involves understanding the pathogen and
the host which both fall under genetic influence," Womack
There are an estimated 30,000 - 40,000 genes in the mammal all
of which have approximately the same amount of genetic information
whether it be cattle or human. Finding where those genes are on a
genetic map is a big step to finding the gene and determining what
changes the gene makes in a sick or healthy person or animal.
Angela G. Clendenin
Director, Communications & Public Relations
Ofc - (979) 862-2675
Cell - (979) 739-5718
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