Protein Constituents of Spermatozoa 1 03 



(Soo) for a 0-22% solution in 0-2M-NaCl is 5-7, a value which re- 

 sembles closely that given by an undegraded specimen of calf 

 thymus nucleic acid. According to Elmes, Smith and White (1952), 

 the molar proportions of the purine and pyrmidine bases in deoxy- 

 ribonucleic acid from human sperm and tissues are: guanine 0-92 

 (standard error of observations 0-036), adenine 1-23 (0-068), cyto- 

 sine 0-84 (0077), thymine 1-01 (0-09) and 5-methylcytosine 0-03. 



Table 14. Salmon sperm deoxyribonucleic acid (Chargaff et al, 1951) 



(Molar ratios between the bases.) 



Purines to pyrimidines 1-02 



Adenine to thymine 1-02 



Guanine to cytosine 1-02 



Adenine to guanine 1-43 



Thymine to cytosine 1 -43 



The analysis of the nucleic acid obtained from the sperm nucleo- 

 protamine of salmon, Salmo salar (Chargaff, Lipschitz, Green and 

 Hodes, 1951) gives a good illustration of the regularity in the com- 

 position of deoxyribonucleic acid. The nucleoprotamine was pre- 

 pared by extraction with a salt solution, the nucleic acid set free by 

 chloroform-octanol treatment, and after some further purification, 

 recovered as the sodium salt. Two specimens were isolated in this 

 way, containing 14-3% nitrogen and 8-9% phosphorus and 14-8% 

 nitrogen and 8-9% phosphorus, respectively. The ultraviolet absorp- 

 tion spectrum measured in M-phosphate buffer pH 7-1, exhibited 

 a maximum at 260 mi-i. The specific viscosity in distilled water at 

 30-3°, was found to be 29-6 for a 0-22% solution, and 5-6 and 20 

 for 0-11 and 0-055% solutions, respectively. The bases were set 

 free by acid hydrolysis and analysed chromatographically and 

 spectroscopically. The ratios of the purine to the pyrimidine bases, 

 of adenine to thymine, and of guanine to cytosine equalled unity; 

 adenine and thymine exceeded guanine and cytosine by about 40% 

 (Table 14). 



Not only the composition but also the content of deoxyribonucleic 

 acid in the cell nucleus appears to be fairly constant and characteris- 

 tic for each animal species. The haploid nucleus of the sperm cell, 

 however, differs from the diploid nuclei of the somatic cells in that 

 it contains a reduced amount of chromatin and consequently it is 



