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The effects of ionizing radiations on the chromosomes ofTradescantia bracteata. A comparison between neutrons and X-rays

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Summary

1. Neutrons produce qualitatively the same types of chromosome aberrations as X-rays, but more of all types of aberration are produced, per ionization, by neutrons.

2. The ratios of the dose of X-rays to the dose of neutrons both measured in roentgens, required to produce equal numbers of aberrations are 2-4 for chromatid breaks, 3-6 for isochromatid rejoins, 4-5 for chromosome breaks, and from 10 to 5, at the doses used, for interchanges.

3. Many of the interchanges produced by neutrons are caused by single ‘hits’, that is by single ionization paths.

4. Neutrons and X-rays do not differ in any effects that they may have on the rejoining process.

5. The results are attributed to the greater number of primary breaks, and their different distribution, when they are produced by the denser ionization paths of neutron radiation.

6. It must be inferred that more than one ionization is needed to break aTradescantia chromosome thread.

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Authors and Affiliations

  1. Botany School, Cambridge

    J. M. Thoday

  2. The Strangeways Laboratory, Cambridge

    D. E. Lea

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  1. J. M. Thoday
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  2. D. E. Lea
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Thoday, J.M., Lea, D.E. The effects of ionizing radiations on the chromosomes ofTradescantia bracteata. A comparison between neutrons and X-rays. Journ. of Genetics 43, 189–210 (1942). https://doi.org/10.1007/BF02982753

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