Table 1.

Relative nitrogen-to-phosphorus ratios of representative cellular structures

No.	Structure type	N/P ratio
1	Mitochondrion	5.38
2	Ribosome-depleted cytoplasm	4.44
3	Nuclear pores	3.23 ± 0.30
4	RNP-depleted nuclear matrix	3.37
5	Interchromatin granule cluster	3.04
6	Nucleolus (granular component)	1.42
7	Chromatin	0.97

The numbers indicate regions identified in Figure 3. Integrated density for regions containing, with the exception of nuclear pores, at least 1000 pixels were calculated in both the net nitrogen and net phosphorus images. The resulting nitrogen and phosphorus values were then used to determine the net nitrogen-to-phosphorus ratio (N/P ratio).