NUCLEOLAR CHANGES IN RELATION TO ATP 

 M. YOSHIDA and C. M. POMERAT 



Tissue Culture Laboratory, University of Texas Médical Branch, 



Galveston, and the Pasadena Foundation 



for Médical Research, Pasadena, Califomia 



The effects of nucleosides and nucleotides on the cell hâve been reported 

 mainly with référence to their action on mitosis and growth. The litera- 

 ture describing their inhibitory effects has been reviewed by Brachet 

 (1957). However, adenosine and yeast adenylic acid were demonstrated 

 to be ineffective in the production of mitotic aberration (Biesele et al. 

 1952). Adenosine was also proven to cause changes in the shape of the 

 nucleoli of chick osteoblasts (Hughes, 1952). There is little data on the 

 effect of adenosine triphosphate (ATP) on the living, intact cell. Thèse 

 studies show that ATP from an extemal source cause (1) cytoplasmic 

 rigidity (Runnstrom and Kriszal, 1950), (2) reversai of the effect of 

 colchicine on mitosis (Lettre, 1950), and, (3) changes in the viscosity 

 of protoplasm (Zimmerman et al. 1958). 



Notable altérations in the structure and function of cells in culture 

 followed treatment with 1*8 mg/ml of ATP and adenosine monophosphate 

 (AMP) at 18 mg/ml for two hours. Upon their return to nutrient média, 

 the following changes were observed in the nucleoli: (1) decrease in 

 their number, (2) change to a spherical form with a higher optical density, 

 (3) central vacuolation of rounded forms, (4) in addition to the formation 

 of fine, dense granules and amoeboid masses in the cytoplasm. Similar 

 results were obtained when AMP was substituted for ATP; however, 

 the concentration required was about ten times greater. Thèse observa- 

 tions were made with time-lapse cinematography. 



Sodium phosphate was toxic to the cells at the same concentration 

 as the ATP. It was of interest that cells with a single, dense nucleolar 

 form showed continued mitotic activity and that very small multiple 

 nucleoli were formed in the daughter cells. In untreated controls, ir- 

 regularly shaped nucleoli with indistinct margins showed the présence 

 of both desoxy and ribose nucleic acids. However, loss of DNA in the 

 rounded nucleoli following ATP was shown with the use of the Feulgen 

 reaction as well as with pyronin-methyl green and gallocyanine staining. 

 There appeared to be no gross change in RNA. The aggregation of DNA 

 was confined to the margin of the nucleoli. Thèse results may prove 

 useful in the study of nucleolar organizers. 



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