THE TIMING OF INDUCED MUTATIONS IN STREPTOMYCES

摘要

It is not known for certain whether x-ray-induced mutations occur during the irradiation or at some later time. However, the present ex periments with Streptomyces indicate that we should not too hastily sup pose the biological part of the process to be either simple or rapid.nIt is suggestive that ultraviolet-induced mutations are not completed until after some considerable delay. Thus in the present material the mutagenic effects of ultraviolet remain partially photorever sible until the nucleus is somewhat less than halfway towards becoming visibly di vided. Influences which delay the nuclear division also delay the trans ition from a photorever sible to a photostable effect, and it is inferred that a step in the events leading to the final mutation is dependent on the postirradiation cell metabolism.