Base composition of nuclear DNA can be estimated by separate analyses using fluorochromes showing preference to AT- or GC- rich regions of DNA relative to a known standard.
Figure 24. Histograms of relative nuclear DNA content in maize (M) and human leukocytes (L) obtained after staining with fluorescent dyes differing in DNA base preference. Human leukocytes were used as an internal standard. (FR = ratio of G1 peak means of leukocyte and maize nuclei)
Table 5. Estimation of DNA base composition in six plant species using flow cytometry. Human leukocytes (AT = 59,5%) were used as a reference standard.
| Species | 2C (pg) | AT (pg) | AT (%) | GC (pg) | GC (%) |
| R. sativus | 1.11 | 0.78 | 46.99 | 0.88 | 53.01 |
| L. esculentum | 1.96 | 1.51 | 50.17 | 1.5 | 49.83 |
| Z. mays | 5.72 | 2.5 | 44.88 | 3.07 | 55.12 |
| H. sapiens | 7 | 4.17 | 59.5 | 2.83 | 40.5 |
| P. sativum | 9.07 | 5.97 | 61.42 | 3.76 | 38.58 |
| V. faba | 26.9 | 18.32 | 62.31 | 11.08 | 37.69 |
| A. cepa | 34.76 | 29.88 | 69.85 | 12.9 | 30.15 |
| 2C = 2C nuclear DNA content AT sample = AT reference ×fluorescence ratio GC sample = GC reference ×fluorescence ratio AT (%) = AT / (AT + GC) ×100 GC (%) = GC / (AT + GC) ×100 |
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