PH03 Perchlorate
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH053) Genotoxicity in Xenopus laevis Exposed to Sodium Perchlorate and UV Radiation.
McDaniel, Les1, Theodorakis, Christopher1, 1 Texas Tech University, Lubbock, TX, USA
ABSTRACT- Four hundred fifty Nieuwkoop-Faber stage 50 Xenopus laevis larvae were exposed to combinations of UVB and sodium perchlorate. Larvae Sodium perchlorate concentrations were 0 ppm, 50ppb, or 10ppm. Perchlorate exposure groups were further subdivided into UVB treatments where half received 0 and the remaining half 100mJ/cm2/day. Larvae were reared in FETAX media within 37.9L glass aquaria from hatch until stage 50 (pre-limb bud, NF) then transferred to 1.0L glass beakers for exposures. All animals received continuous gentle aeration from hatch to day 70 post-hatch. Exposures were carried out in a Precision Scientific model 815 microprocessor controlled low temperature incubator adapted to uniformly deliver UV radiation. A 12:12 (light:dark) cycle was maintained by digital timers with 20w cool white fluorescent bulbs. Ultraviolet light was similarly produced by digital timer-controlled 20w UVB fluorescent bulbs with an on:off cycle set appropriately to deliver daily dosage and to approximate a natural midday peak of UV. Upon exposure completion, tadpoles were staged, a 0.5cm section of the base of the tail collected for histology, and the remaining tail tissue stored in liquid nitrogen for DNA damage analysis. Tail tissue from three animals from each replicate were pooled for DNA extraction and purification. Single and double strand break analysis were performed using agarose gel electrophoresis. Pyrimadine dimers were assessed using a combination of UVDE (UV dimer endonuclease) digestion and agarose gel electrophoresis. Preliminary results demonstrated an association between increased DNA damage and simultaneous exposure to perchlorate and UV. Examination of specimens likewise demonstrated correlation between thyroid-repressed (perchlorate-exposed) individuals and increased susceptibility to UV radiation as quantified by incidence of skin damage.
Key words: perchlorate, Xenopus laevis, UV