CYTOLOGy 6-40 



THE POSSIBLE ROLE OF VOLUTIN (METAPHOSPHATE) AND 

 NUCLEIC ACIDS IN CONFERRING SPECIFICITY 

 TO CELLULAR ENZYMES 



Wiame has presented convincing evidence supporting the view 

 that volutin is metaphosphate. Assuming that his theory is correct, 

 one may develop the following hypothesis: 



The chromosomes in resting cells do not stain either with iodine 

 or with the volutin stain. However, shortly after resting cells are 

 placed in a nutrient medium the chromosomes stain dark brown 

 with iodine (fig. 6-27). After this has occurred they stain pink with 

 the volutin stain. This suggests that the energy for transferring 

 orthophosphate to metaphosphate is obtained from the localized 

 carbohydrate. The metaphosphate which is synthesized from or- 

 thophosphate on the chromosome is transferred to the nucleolus. 

 The synthesis of nucleic acids occurring in the nucleolus depends 

 upon a supply of metaphosphate originating in the chromosomes, 

 and the specificity of cellular enzymes may be associated with this 

 phenomenon, since genes are known to control the specificity of 

 various cellular enzymes. Von Euler and Janssens showed that 

 the apoenzyme (protein) components of cellular enzymes are re- 

 sponsible for their specificity, and this important fact was recently 

 confirmed by Spiegelman, Reiner, and Morgan; Caspersson and 

 Schultz showed that nucleic acids are synthesized in the nucleolus 

 and transferred from the nucleolus to the cytoplasm. They have 

 suggested that these nucleic acids transfer the genetic specificities 

 from the nucleus to the cytoplasm. I would like to propose that 

 the transfer of the polymerized metaphosphate from the chromo- 

 some to the nucleolus determines the specificity of enzymes whose 

 synthesis is under genetic control. The energy-rich phosphate 

 bond in metaphosphate furnishes the energy which is required for 

 the synthesis of the nucleic acids in the nucleolus, as well as of the 

 materials which make up the chromosome itself. The syntheses oc- 

 curring in the nucleolus initiate the production of specific enzymes, 

 suggesting that the metaphosphates carry specificity-conferring 

 groups with them from the chromosome to the nucleolus, which give 

 specificity to the nucleic acids synthesized in the nucleolus. 



Bauer and Caspersson have shown that a transfer of Feulgen- 

 positive, and ultraviolet-absorbing substance take place from the 

 chromosomes to the nucleolus in Chironymus. Rafalko and I have 

 shown that the nucleolus in the yeast cell is on rare occasions Feulgen- 

 positive. These facts suggest that metaphosphate and desoxyribose 

 nucleic acid are transferred from the chromosomes to the nucleo- 

 lus to confer specificity to nucleolar material. Callan has shown 

 that in frog eggs the nuclear membrane is too fine to permit the 

 passage of proteins. If this be true in yeasts the specificity con- 

 ferring compound which passes into the cytoplasm may not be very 

 large. 



