摘要:

SYNOPSISThe RNA content of a population ofTetrahymena pyriformisW was followed during the growth phases of the culture. The cellular RNA levels were found to reach a maximum in early log phase and to decrease throughout the remainder of the log and deceleration phases. There was a 25% decrease in RNA amount when cells in late stationary phase were compared to those in deceleration. This loss of RNA was mimicked when cells from the deceleration phase were suspended in a non‐nutrient buffered medium.Procedures were established to determine RNA content and the intra‐ and extracellular distribution of RNA degradation products, namely purine and pyrimidine bases and orthophosphate. Balance sheets are presented to show that the decrease in RNA levels was accompanied by an equivalent increase in purine and pyrimidine bases and phosphorus derivatives. The validity of the procedures employed was demonstrated. The influence of magnesium, cholesterol and glucose on the cells suspended in a non‐nutrient buffer was examined. Each was found to affect the ultimate distribution of RNA products in a characteristic fashion suggesting that each compound acts by a different mode of a

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1974.tb03633.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SYNOPSISCultures ofTetrahymena pyriformisin a non‐nutrient buffer degrade RNA and excrete hypoxanthine, uracil and orthophosphate. Glucose addition leads to the retention of a portion of the purine, pyrimidine, and orthophosphate by the cells; however, the hexose has little influence on the RNA level. Acetate supplementation has no effect on RNA degradation or on the distribution of the catabolic products between the cells and the environment.Interruption of oxidative phosphorylation by 2,4‐dinitrophenol results in an increase in RNA degradation. This action is annulled by the glycolytic substrate, glucose, but not by acetate. A combination of iodoacetic acid and glucose blocks glycolysis and increases cellular RNA loss which can be reversed by the addition of the citric acid cycle substrate, acetate. These findings suggest that the available cellular energy supply in starved cells is sufficient to regulate the rate of RNA degradation. Disruption of ATP generation by the appropriate inhibitors, however, allows the demonstration of the importance of energy‐yielding reactions in the determination of the amount of nucleic acid loss. It appears that glycolysis and oxidative phosphorylation are equally efficient in sustaining the regulatory process.RNA synthesis during starvation conditions is a discontinuous process with a sharp rate change after 30 min of incubation. 2,4‐Dinitrophenol inhibits [2‐14C] uracil incorporation into the nucleic acid. Glucose does not annul the inhibition of synthesis in contrast to the influence of the hexose on RNA degradation. This observation demonstrates that the synthetic and degradative processes are not directly coupled.Glycogen synthesis and RNA degradation appear to compete for the available energy supply and respond in a similar fashion to the metabolic inhibitors and carbo

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1974.tb03634.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1974.tb03635.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1974.tb03636.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1974.tb03637.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Book reviewed in this article:Levine, N. D. 1973.Protozoan Parasites of Domestic Animals and of Man

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1974.tb03638.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1974.tb03639.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY