| 
HORSE CURES OF THE FUTURE: A MAP WOULD HELP
by Cathy L. Smith
Dr. Ernest Bailey approaches his daily travels
with maps of a different sort. He works on maps of the equine
genome. Bailey, a geneticist at the University of Kentucky’s
Gluck Equine Research Center, is one of a group of researchers
worldwide who are mapping out the equine genome with an eye
toward combating disease.
The Equine Genome Project, a study that began
in 1995, will define gene functions in the hereditary library
of the horse. By finding out where each gene is located on
the chromosome and what it is for, scientists hope to streamline
their search for disease cures. The word “genome”
encompasses the study of all genes and chromosomes.
For lay-people, a lesson in basic biology
might be appreciated: All living things are comprised of cells.
The mammalian cells have a nucleus containing chromosomes—strands
made up of DNA. On the chromosomes are genes which are lined
up in a specific order. The genes instigate protein construction.
Proteins are molecules with a specific function in the body.
Genes are responsible for the traits that typify an individual,
but may also be responsible for an individual’s tendency
toward developing disease.
There are 20,000 genes in each mammalian cell.
Currently, 1,000 to 1,500 have been identified as to function
in the equine to date. The more markers on a gene map, the
more powerful a tool it becomes. Of course, the most powerful
map is a whole genome sequence—like those already completed
of humans, mice, dogs, cattle and chickens. Genome studies
on sheep, cats, and swine are underway. And a complete genome
map of the horse is under discussion.
Cell expression is a significant part of genome
research. “Expression” in this case means when
the genes become active and make proteins. Cells from different
tissues express different sets of genes, so the grouping of
genes is characteristic of cell function. They can also be
modified by physiological, immunological or chemical stimulation.
Scientists measure and compare the type and amount of gene
product expressed by the tissues in health and disease. Bailey
said at any time, 10,000 genes will be expressed in a cell.
Understanding the combinations of gene expressions is complicated
and researchers must use computers to analyze the information—a
discipline called bioinformatics. The end product, however,
will be a simple diagnostic test for the one or two genes
that affect the treatment or disease.
Bailey and others plan to use genome information
to prevent or cure certain illnesses in horses. Once the map
is complete, researchers can learn what genes influence the
outbreak of disease. A study into how gene expression of specific
tissues is altered can pave the way for researchers to intervene
and help the afflicted horse. Gene expression can also show
the effect of vaccines and exposure to infectious agents.
With such information, Bailey said, scientists can conduct
more relevant experiments in search of a cure.
“If we don’t have the gene sequences
for the horse, we will be limited in the experiments we can
conduct. This will be a major tool for doing research in the
21st century,” he said.
The work on equine genome mapping is a collaborative
effort involving several hundred researchers in several facilities
across the nation and in at least 12 countries. This is in
part due to the fact that the work is so cost-prohibitive
and funding is more readily available for research focusing
on food animals. Bailey estimates the cost to complete the
equine genome study will top the $10 million mark.
|
