10. D N A A N D R N A S Y N T H E S I S
337
I00r
o'
'
40
'
80
'
120
'
160 '
2 0 0
- "
240 "~
Total nuclear dry mass xlO~
12
g
FIG. 5. Ultraviolet absorption (total nucleic acid) and Feulgen stain (DNA) measurements
for individual HeLa tumour strain nuclei plotted against the corresponding dry mass values
(from Fig. 3).
A least squares analysis gives the correlation coefficient of r = 0-885 between dry mass
and total nucleic acid but a significantly lower correlation coefficient of r = 0-718 between dry mass and D N A (t — 4-40, exceeding the value to be attained at the P = 0-001
level (t = 3-30)). There is no significant non-linearity in the regression of total nucleic acid
on dry mass (F = 0-35 only, whereas F = 2-27 is required at the P = 0-05 level); however, a significant non-linearity is found in the regression for D N A on dry mass (F = 6-23,
exceeding that to be attained (F = 3-17) at the P = 0-01 level).
Total nuclear nucleic acid xlO
H2
g
Relative amount of Feulgen stain (DNA)