Genetic variation in resistance to ionizing radiation
We proposed an investigation of genetically-determined individual differences in sensitivity to ionizing radiation. The model organism is Drosophila melanogaster. The gene coding for Cu,Zn superoxide dismutase (SOD) is the target locus, but the effects of variation in other components of the genome that modulate SOD levels are also taken into account. SOD scavenges oxygen radicals generated during exposure to ionizing radiation. It has been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Two alleles, S and F, are commonly found in natural populations of D. melanogaster; in addition we have isolated from a natural population null'' (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide an ideal model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CA1. The roles of SOD level in radioresistance are being investigated in a series of experiments that measure the somatic and germ-line effects of increasing doses of ionizing radiation. In addition, we have pursued an unexpected genetic event-namely the nearly simultaneous transformation of several lines homozygous for the SOD null'' allele into predominately S lines. Using specifically designed probes and DNA amplification by means of the Tag polymerase chain reaction (PCR) we have shown that (1) the null allele was still present in the transformed lines, but was being gradually replaced by the S allele as a consequence of natural selection; and (2) that the transformation was due to the spontaneous deletion of a 0.68 Kb truncated P-element, the insertion of which is characteristic of the CA1 null allele.
- Research Organization:
- California Univ., Irvine, CA (United States). Dept. of Ecology and Evolutionary Biology
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-88ER60713
- OSTI ID:
- 5696596
- Report Number(s):
- DOE/ER/60713-T1; ON: DE92005588
- Country of Publication:
- United States
- Language:
- English
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Genetic variation in resistance to ionizing radiation
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
DROSOPHILA
GENETIC VARIABILITY
ENZYMES
GENETIC RADIATION EFFECTS
IONIZING RADIATIONS
PROGRESS REPORT
STERILITY
ANIMALS
ARTHROPODS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL VARIABILITY
DIPTERA
DOCUMENT TYPES
FLIES
FRUIT FLIES
GENETIC EFFECTS
INSECTS
INVERTEBRATES
ORGANIC COMPOUNDS
PROTEINS
RADIATION EFFECTS
RADIATIONS
560152* - Radiation Effects on Animals- Animals
550400 - Genetics