| Popis: |
Mass cultures of S. typhimurium have been induced to undergo synchronous nuclear and cellular divisions by means of temperature shifts. During the course of such experiments the synthesis of DNA, RNA and cell mass have been followed. It is concluded that the primary effect of raising the temperature from 25° to 37° is to induce DNA synthesis which, almost at once, leads to nuclear division. Repeated temperature shifts eventually induce synchronous cell division and amss synthesis. The division cycle of this organism seems to consist of an early period characterized by DNA and mass synthesis followed by a period without DNA or mass synthesis but with enhanced RNA synthesis. It is discussed to what extent results obtained in experiments of this type may apply to freely growing cells. |
