## Abstract When cycloheximide (0.2 ΞΌg per ml) was added to synchronized cultures of __Tetrahymena pyriformis__ GLβC, the initial rate of incorporation of ^14^Cβleucine was reduced to about 20% of the rate observed in control cells. After one hour, the rate increased fairly abruptly to about 60% of
The kinetics of resensitization of Tetrahymena following recovery from effects of cycloheximide
β Scribed by Carolyn B. Heyer; Joseph Frankel
- Publisher
- John Wiley and Sons
- Year
- 1971
- Tongue
- English
- Weight
- 634 KB
- Volume
- 78
- Category
- Article
- ISSN
- 0021-9541
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β¦ Synopsis
Synchronized cells of Tetrahymena pyriformis strain GL-C were exposed to cycloheximide (CHI) (0.2 pg per ml) from 40 to 140 minutes after the end of the heat synchronizing treatment. Recovery takes place during this treatment (Frankel, '70). The CHI was washed out at 140 minutes. At various times after washout dividing cells were isolated in micro-drops under oil, and one daughter was transferred to a test drop containing CHI (0.2 pg per ml). The generation time of both daughters was recorded, and the "percent prolongation" of generation time brought about by the test exposure of one cell to CHI was computed for each cell-pair. This procedure was carried out for groups of cellpairs at different times after the end of the CHI pretreatment. Comparable tests were performed with two control series, one which had not previously been exposed to CHI and another for which CHI was present continuously. Comparison of the prolongation observed in control and experimental series demonstrated that cells which have earlier undergone recovery in CHI gradually become resensitized following washout of the drug. Cells progressively lose most of their original resistance in a period of somewhat over three cell generations; however, a small but significant fraction of this resistance is still retained seven to eight generations after the CHI pretreatment.
π SIMILAR VOLUMES
## Abstract __Tetrahymena pyriformis__ were grown in axenic culture to late logarithmic and stationary phases, resuspended in an inorganic medium, and the rates of transport of Ξ±βaminoisobutyric acid (AIB) and of the decarboxylation of Lβ[1β^14^C]leucine and Lβ[1β^14^C]tyrosine were measured. There
Intracellular ribonuclease from the ciliate Tetrahymena pyriform.is GL was purified 10-fold. After preheating for 20 minutes at 100Β°C of the ribonuclease preparation 80% of its activity was lost. Preheating under the same conditions, however, in the presence of RNA, did not affect the enzyme activit