The Molecular Nature of Mutants Induced by X Rays Is Altered by the Presence of the Radioprotector Cysteamine

• Published in: Radiation research 1989-05, Vol.118 (2), p.324-329
• Main Authors: Liber, Howard L., Benforado, Katherine, Little, John B.
• Format: Article
• Language: English
• Subjects: Amines; Biological and medical sciences; Biological effects of radiation; Blotting, Southern; Cell Line; Cell Survival - drug effects; Cell Survival - radiation effects; Cysteamine - pharmacology; Dosage; Dose response relationship; Fundamental and applied biological sciences. Psychology; Gene deletion; Genetic loci; Genetic mutation; Humans; Hypoxanthine Phosphoribosyltransferase; Hypoxia; In Vitro Techniques; Irradiation; Mutation; Point mutation; Radiation Genetics; Radiosensitizing agents. Photosensitizing agents. Thermosensitizing agents; Solar X rays; Tissues, organs and organisms biophysics
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3577446

The molecular structure of mutants induced in human lymphoblast cells by 500 cGy X rays in the presence of the radioprotector cysteamine (25 mM) has been compared with that induced by an equally mutagenic treatment of 150 cGy X rays alone. Sets of mutants at the hypoxanthine-guanine phosphoribosyl transferase locus were analyzed by Southern blot. Of 24 mutants induced by X rays in the presence of cysteamine, 67% exhibited no change in the restriction fragment pattern and thus were defined as point mutations; 8% appeared to be total gene deletions and 25% were partial deletions or rearrangements. In contrast, among 28 mutants induced by X rays alone (Liber et al., Mutat. Res. 178, 143-153 (1987)), 46% were point mutations, while 50% were total gene deletions and only 1 mutant (4%) was a partial deletion or rearrangement. Thus mutants isolated in the presence of cysteamine consisted of more point mutations and partial deletions/rearrangements, and considerably fewer total gene deletions. These results suggest that cysteamine may protect selectively against processes which lead to large-scale molecular changes.