Abstract
Effect of the Medium on Radium-sensitivity of Cells IN a communication addressed to the Editor, Dr. G. Harker, of the Cancer Research Committee, University of Sydney, describes the extension of his observations (NATURE, 137, 190; 1936) on the inhibiting effect of radiation from radium plaques on the inversion of sucrose by living yeast cells, an effect now found also with X-radiation. If during irradiation with radium the cells are kept in suspension by gentle stirring, the inversion of sucrose is less than in the unstirred cells, although, owing to settling, the latter are much closer to the radium. The magnitude, and even the direction, of this effect are dependent on the neutral salt content of the medium. Since Loof-bourow et al. (NATURE, 139, 589; 1937) have shown that stimulating substances may be liberated from irradiated cells, Dr. Harker removed the aqueous suspension fluid by centrifuging the suspension of cells after 18 hours irradiation by 30 mgm. of radium, and re-suspended the cells in fresh sucrose. It was found that the passage of substances from the cells into the liquid increased inversion in both this and the non-irradiated control specimen, but the increase was greater in the irradiated one. When the cells were irradiated in 10 per cent sucrose solution with the same quantity of radium, after 5 hours exposure the extent of inversion by the re-suspended yeast was less than that of the control; after 18 hours it was greater. It is concluded that in the early stages stimulating, and in the later stages inhibiting, substances are given off into the solution by irradiated yeast cells, and that the solution in contact with the -cells plays an important part in these effects.
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Research Items. Nature 141, 84–85 (1938). https://doi.org/10.1038/141084a0
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DOI: https://doi.org/10.1038/141084a0