Dj. Bruggeman et al., LINKING TERATOGENESIS, GROWTH, AND DNA PHOTODAMAGE TO ARTIFICIAL ULTRAVIOLET-B RADIATION IN XENOPUS-LAEVIS LARVAE, Environmental toxicology and chemistry, 17(10), 1998, pp. 2114-2121
The frog embryo teratogenesis assay-Xenopus (FETAX) was used to illust
rate sublethal endpoints indicative of ultraviolet B (UV-B) radiation
exposure in Xenopus laevis larvae. Xenopus laevis embryos were covered
with plastic cutoff filters to manipulate UV dose, and irradiated und
er a light carriage consisting of two UV-B and three W-A bulbs. At the
end of day 2, 20% of the tadpoles from all treatments were removed, a
nd DNA was extracted. Frequency of pyrimidine dimers was estimated by
quantifying single-strand breaks after incubating DNA with an endonucl
ease specific for cyclobutane pyrimidine dimers. Remaining tadpoles we
re sacrificed on day 5, and mortality, malformations, and growth data
were recorded. Teratogenesis and growth inhibition were positively cor
related with increasing UV-B dose in all tests. Photodamage to DNA in
experiment 1 increased with higher UV-B doses. Teratogenesis positivel
y correlated with the frequency of pyrimidine dimers. In experiment 2,
significant variation with DNA photodamage in egg clutches was observ
ed and no treatment effect was found. Usage of these sublethal endpoin
ts in the field or laboratory would be helpful in discerning adaptatio
nal responses of developing amphibians to UV-B radiation, and interact
ive effects between UV and photosensitive chemicals.