178 



CELL HEREDITY 



TABLE 7.1 

 DNA Content of Various Cell Types 



Values Given in Picograms = 



10~ '" Grams Per Nucleus 



Haploid 



Diploid 



Bacteriophage TA 



E. coli 



Yeast 



Sctirospom 



.Xsper^illus 



Drosophila 



'Lea mays 



Mouse 



Rat 



Beef cattle 



Man 



Domestic fow I 



Shad 



Carp 



Rainbow trout 



Toad 



Frog 



2 X 10"'' 

 1 X 10"- 

 2.3 X 10"^ 

 4 X 10~- 

 4x 10"- 



3.3 



1.3 

 0.91 

 1.6 

 2.45 



3.7 



1.7 X 10"' 

 7 

 5 



6.5-7.6 

 6.4-6.8 

 6.0-6.8 

 2.4-2.6 

 1.99 

 3.0-3.3 

 4.9 

 7.3 

 15.0 



CHEMICAL COMPOSITION OF CHROMOSOMES 



Information concerning chromosome chemistry has been obtained with 

 a variety of methods including staining with specific dyes, photometric 

 measurements of chromosome-dye complexes and of UV absorption by 

 unstained material, enzymatic hydrolysis, autoradiography to measure 

 the incorporation of radioactive elements, and chemical studies of ex- 

 tracted nuclear constituents. 



The localization of DNA in the chromosomes was first demonstrated 

 by Feulgen in 1924 by the utilization of the Schiff reaction (mild acid 

 hydrolysis to liberate purines from DNA, leading to aldehvde formation 

 at the (>-l of the deoxyribose, and the appearance of a purple color 

 from the reaction of aldehvdes with basic fuchsin ). DNA occurs el.se- 

 where in cells in detectable amounts onlv under special conditions such 

 as \ irus infection, and as storage material in the egg cells of some organ- 

 isms. It has also been found in the basal bodies (kinetoplasts) of 

 flagella. 



Quantitative m(>asurements ol the i^NA content per cell ha\e been 

 carried out by chemical extraction, which pro\ ides average values in 



