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2004
LSU-HHMI Summer Undergraduate Research Program |
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 Cheryl
Lee, John Battista, Biological Sciences
Characteristics of DNA damage repair following ionizing
and UV radiation in Deinococcus radiodurans and two single mutant
strains ΔuvrA, ΔpolA, and the double mutant vuvrA & ΔpolA
Deinococcus radiodurans possesses an extremely efficient
DNA repair system, which allows it to withstand radiation-induced
DNA damage. UV radiation causes the formation of thymine-containing
pyrimidine dimers throughout the DNA. Gamma radiation creates
lesions in both the bases and sugar residues of DNA, resulting
in single and double strand breaks. Following ionizing radiation,
the hundreds of double strand breaks introduced are cell lethal,
but D. radiodurans has the ability to repair its chromosome
without any loss of viability or induction of mutagenesis. A
few mutant strains of D. radiodurans were analyzed
for their ability to tolerate UV and ionization radiation. Pulsed-field
gel electrophoresis was used to investigate whether Strain R1
(wild type), Strain 302 (ΔuvrA), IRS 50 (ΔpolA &
ΔuvrA), and IRS 501 (ΔpolA) were able to reassemble
their chromosomes post-irradiation of 500 J/m2 UV or 5 kGy ionizing
radiation (IR). Furthermore, the fraction survival after increasing
doses of UV and ionization radiation was calculated for each
of the strains. Of the strains examined, IRS 501 was both UV
and IR sensitive, IRS 50 was only IR sensitive, and Strain 302
– except for delayed recovery after 5 kGy ionizing radiation
– exhibited behavior similar to that of the wild type.
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