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The Contribution of Delta Rays to the Chromosome Aberration Dose Response in Human Cells Irradiated with HZE Particles of Different Energy but the Same LET (NNX14AC76G)
Principal Investigator
Research Area:
Radiation health
Species Studied
Scientific Name: Homo sapiens Species: Human

Highly energetic heavy ions (HZE), of the type found in galactic cosmic rays, deposit energy in the form of ionizations along the tracks they take as they travel through a cell. These ionizations are tightly spaced along these tracks and this spacing makes them highly damaging to cellular structures. Some of the particles energy is also imparted to electrons (delta rays) which can travel great distances and produce damage, albeit less severe, in cells far removed from the original particle track. The ranges of these electrons are proportional to the energy of the original HZE particle. While these delta rays by themselves are not likely to produce much in the way of measurable damage, investigators have evidence that these electrons can add damage to that forming along independent HZE particle tracks that will eventually be expressed in the form of chromosome exchanges of greater complexity.

Chromosome exchanges result when radiation breaks a chromosome by severing the DNA of which it is composed. The cell has means to repair the chromosome and can splice the DNA together. On some occasions, if one chromosome break is close to another break, the cell might make a mistake and join the broken ends to inappropriate partners. Two or more breaks can be involved in the process; the greater the number of breaks, the more complicated the resulting chromosome exchange will be. Investigators plan to test the hypothesis that these exchange complexity increases will be related to the primary particle energy and resultant maximum delta ray range. Higher particle energies will result in longer delta ray maximum ranges allowing more primary particle tracks to be close enough to irradiate a cell with delta electrons for any specific fluence (particle tracks per unit area; equivalent to dose).

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Radiation dosage
Radiation effects
Chromosome aberrations

Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
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Chromosome aberrations
Complex exchange breakpoints
Particle energy
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Human Research Program (HRP) Human Research Roadmap (HRR) Information
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Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Terry Hill
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source
2013 Space Radiobiology N