Sheldon Wolff

TL;DR: If human lymphocytes1 or Chinese hamster2 cells are treated with the base analogue 5-bromodeoxyuridine in the latter part of the S period, Giemsa stained chromosomes exhibit a pattern of condensed and extended segments along their length, allowing the identification of the two chromatids, and the observation of sister chromatid exchanges (SCEs) without recourse to autoradiography.

TL;DR: When human lymphocytes were cultured with [3H]thymidine, which acts as a source of low-level chronic radiation, and then exposed to 150 rad of x-rays at 5, 7, 9, or 11 hours before fixation, the yield of chromatid aberrations was less than the sum of the yields of aberration induced by [3 H]thcyidine and x-ray separately.

TL;DR: The data support the concept that SCEs provide a useful indication of exposure, although the mechanism and biological significance of SCE formation still remain to be elucidated.

TL;DR: Chinese hamster ovary cells grown for two rounds of DNA replication in the presence of BrdUrd contain sister chromatids that fluoresce differentially when stained with Hoechst 33258, and the staining patterns obtained in endoreduplicated cells clearly confirm that the polynucleotide strands of the DNA segregate into sister Chromatids as though the newly synthesized strands were laid on the outside of the replicating double helix.

TL;DR: The initial experiments behind the adaptive response to very low doses of radiation have led to a vigorous worldwide effort to understand the basic mechanisms behind it, and preliminary experiments on the survival of whole-body irradiated mice have shown that multiple exposures to low adapting doses can have profound effects on survival.