A comparison of mutations induced by accelerated iron particles versus those induced by low earth orbit space radiation in the FEM-3 gene of Caenorhabditis elegans

The fem-3 gene of Caenorhabditis elegans was employed to determine the muta tion frequency as well as the nature of mutations induced by low earth orbi t space radiation ambient to Space Shuttle flight STS-76. Recovered mutatio ns were compared to those induced by accelerated iron ions generated by the AGS synchrotron accelerator at Brookhaven National Laboratory. For logisti cal reasons, dauer larvae were prepared at TCU, transported to either Kenne dy Space Center or Brookhaven National Laboratory, flown in space or irradi ated, returned to TCU and screened for mutants. A total of 25 fem-3 mutants were recovered after the shuttle flight and yielded a mutation frequency o f 2.1 x 10(-5). roughly 3.3-fold higher than the spontaneous rate of 6.3 x 10(-6). Four of the mutations were homozygous inviable, suggesting that the y were large deletions encompassing fem-3 as well as neighboring, essential genes. Southern blot analyses revealed that one of the 25 contained a poly morphism in fem-3, further evidence that space radiation can induce deletio ns. While no polymorphisms were detected among the iron ion-induced mutatio ns, three of the 15 mutants were homozygous inviable. which is in keeping w ith previous observations that high LET iron particles generate deficiencie s. These data provide evidence, albeit indirect, that an important mutageni c component of ambient space radiation is high LET charged particles such a s iron ions. (C) 2001 Elsevier Science B.V. All rights reserved.