W
Bioluminescent
Reporters
for
Detection of
Mutagenic
and
Carcinogenic
Environmental
Contaminants
E HAVE DEVELOPED A SIMPLE, RAPID
and sensitive bacterial method for
measuring mutagenicity (DNAdamaging activity) in process streams and
waste site samples. Mutagenicity correlates
strongly with carcinogenicity to humans, and
mutagenic wastes require careful detoxification. A rapid assay for mutagenicity would be
useful in risk assessment for site characterization and would help minimize chemical waste
production by allowing tighter control of
processes to minimize production of carcinogenic wastes and by greatly reducing the volume of contaminated materials created, ironically, by testing itself.
The assay is based on measurement of light
produced by the enzyme luciferase. Light emission can be easily detected with remarkable
sensitivity (detection limit ~10~15 more, or
roughly 40 active E. coli cells) in samples of
less than one mL. This activity can be used in
mutagen detection in two ways. First, as in the
well-known Ames test, the assay can use bacterial cells lacking a specific function because of
previous, deliberate DNA mutations.
Mutagenic activity can be detected because
random DNA alterations occasionally reverse
the inactivating lesion, leading to restored
function with measurable frequency. Unlike the
Ames test, which requires the counting of bacterial colonies on large numbers of Petri plates,
the luciferase assay uses solution-phase detection of light resulting from random repair of
ultradark luciferase mutants developed at the
University of Houston by the research group
headed by Shia-Chun Tu, professor of biochemistry, and our own group.
A second assay format uses cells harboring
active luciferase genes in a format which is
induced in response to DNA damage. The second assay lacks the advantage of mutagen typing by use of strains harboring different
luciferas mutants, but gives a very rapid rise to
mutagen exposure.
This study supported the research and studies of Karine I. Maillard, doctoral student in
biochemistry.
Grant
“Bioluminescence Reporters for Hazardous
Substances,” pre-proposal roposal submitted to
the Gulf Coast Hazardous Substance Research
Center, Fall 1995.
Publication
Willson, R. “Luciferase-based assays of environmental mutagens,” Environmental Science
and Technology. In press.
--Richard Willson, Ph.D.,
Associate Professor,
Chemical Engineering, UH
Dr. Richard Willson stands at an industrial fermenter utilized in experiments
requiring large quantities of recombinant organisms.
Management and Monitoring
EIH • 19
UH/UHCL