|
2002
LSU-HHMI Summer Undergraduate Research Program |
| |
 Philip
Mark Neal (John Battista, LSU Dept. of Biological Sciences)
The Threshold Dose of Ionizing Radiation Required for Inactivation
of Small Circular DNA
Acinetobacter calcoaceticusis, a nonmotile bacterium, readily
undergoes natural transformation and can survive on a variety
of carbon sources. ADP6 is an A. calcoaceticus mutant that lacks
the pcaG gene, a gene which encodes a protein that participates
in the pathway responsible for the degradation of p-hydroxybenzoic
acid (POB). ADP6 is unable to grow on p-hydroxybenzoic acid
as a result of this mutation. pZR1 and pZR2, plasmids that contain
the wild type pcaG gene, restore ADP6’s ability to grow
on POB. Due to the ease at which this phenotype can be selected,
ADP6, pZR1, and pZR2 serve as ideal tools for establishing the
threshold dose of radiation that purified DNA can withstand
and still function as transforming DNA. Ionizing radiation causes
a wide array of DNA damage including base damage and both single
and double strand breaks. An accumulation of this damage would
inactivate a plasmid for use in transformation. Comparing the
transformation rate of ADP6 to POB utilization with irradiated
DNA to the transformation rate of ADP6 transformed with unirradiated
DNA, the threshold dose required for inactivation of small circular
DNA molecules as transforming units can be established.
|
|
|
