DNA Synthesis and Cell Division in Germinating Onion: III. Variation in Apparent Feulgen-DNA Content with Nuclear area Change

SUMMARY

Careful microspectrophotometric analysis of the 2C (Gl) nuclear population of the onion during the critical period of decompaction from the quiescent to the functional state reveals an increase in apparent DNA content correlated with increased nuclear area. This finding is demonstrated not to depend on technical flattening of nuclei, but on the state of chromatin condensation. The probable identity of this phenomenon with that recently reported from mammalian systems is discussed, as are the possible interpretations of cause. It is provisionally concluded that current evidence favors the view that the relationship reflects non-stoichiometric stain-substrate interaction. The relative advantages of the onion system for future work in this area are discussed.