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Environmental concerns over selenium
toxicity in wildlife have re-emerged in recent years and become a topic of
substantial debate. Currently, the U.S. Environmental Protection Agency (EPA)
is considering a new and controversial tissue residue regulatory standard for
selenium, a very different approach than more traditional water quality standards.
However, for such approaches to be effective, a clear understanding of how
selenium accumulates in different organisms, and in different tissues, is required.
As little is known about the accumulation and effects of selenium in reptiles,
scientists at the University of Georgia Savannah River Ecology Laboratory developed
a simplified laboratory food chain to study these processes. Unlike some other
contaminants that may primarily be accumulated by exposure in air or water,
mercury and selenium are ingested primarily in the diet.
Understanding how contaminants travel through the food web and where contaminant
burdens are likely to be found within the subject’s body is ultimately
critical for assessing health risks, according to the authors. Researcher William
Hopkins and others fed commercial feed laden with selenium to crickets that
were then fed to juvenile fence lizards for 98 days. The researchers chose
selenium as the contaminant because of its current focus within the regulatory
community, propensity to accumulate in food webs, and its well-known ability
to cause birth defects in wildlife. Other lizards were fed uncontaminated crickets.
Fence lizards were chosen for this study because they are one of the most common
lizards found in the United States and because their entire life cycle is manageable
in the laboratory. Also, a great deal is already known about their ecology,
physiology, performance and life history.
The researchers found that female lizards fed the contaminated crickets accumulated
the most selenium, especially in the reproductive organs. In fact, they approached
the highest thresholds for reproductive toxicity in egg-laying vertebrates.
This is the first study to document trophic transfer of any contaminant in
a lizard using a laboratory-based food chain.
Though this study shows high levels of accumulation in female lizards, the
researchers observed no consistent effect of dietary treatment on survival
or other, less lethal parameters. However, Hopkins said the simplified food
chain has proven to be an ecologically relevant method of exposing lizards
to selenium and will be used in future studies on maternal transfer and embryonic
malformations. Such studies will help determine whether currently proposed
regulatory criteria are protective of reptiles and amphibians, which is particularly
important since these populations have been found to be declining worldwide.
Maximizing
Research Opportunities
Achieving the top ranks of American research universities,
so critical to the future economic development of Georgia
and to the education of its students, will require an unprecedented
level of commitment from the University and the state of Georgia.
In order to reach that level, UGA will need to focus its current
and new resources on areas of (1) greatest strength; (2) greatest
external funding opportunity; and (3) greatest opportunity
for national distinction. These areas of strength with great
external funding opportunity are
• environmental sciences
• biosciences generally and genomics in particular
• the biomedical area
• technologically aided agricultural research and service
programs, such as digital imaging and diagnostics.
Those with greatest opportunity for additional national recognition
include history, public and international affairs, areas of
English such as humanities computing; art; and music, including
the digital music program.
Critical to the success of the research program at UGA is
the construction of badly needed research facilities in these
areas of institutional strength. The Center for Applied Genetic
Technologies, which includes transgenic research facilities
for cattle, poultry, swine, fish and most major crop plants,
is now fully operational. A new facility for the Complex Carbohydrate
Research Center is on schedule to open by the end of 2003.
Additionally, facilities such as a major hospital for Veterinary
Medicine; an addition to the College of Pharmacy, including
space to support biomedical initiatives in cooperation with
the Medical College of Georgia; and substantial new facilities
to support the life sciences, including the College of Environment
and Design, the Institute for Integrated Genomics and the
Center for Tropical and Emerging Global Diseases, will expand
UGA’s role in these crucial areas.
The research under way at the University of Georgia, across
a wide array of disciplines, enhances lives, spurs economic
development and advances knowledge.
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