Nuclear Proteins During the Onset of Cell Proliferation in Pea Root Meristems

The DNA: proteins ratio in nuclei of root meristems of pea (Pisumsativum L. cv. Lincoln) changed considerably during germinationas cells moved from a quiescent to an actively proliferatingstate with a higher protein content in nuclei of the latter.Electrophoretic patterns of nuclear proteins extracted at differenttimes of germination were used to examine qualitative changes.The various patterns presented a substantial similarity butthere were some proteins whose content increased or decreasedand others which disappeared or appeared during germination.The bulk of these variations occurred between 24 and 48 h ofgermination, suggesting that they might be correlated to thetransition from quiescence to the proliferating state. The patternof nuclear proteins obtained from adult differentiated roottissue was also examined. We tried to purify five differentnuclear protein components from intact nuclei by a multi-stepextraction procedure using a series of different buffers toascertain the nature of proteins presenting major interestingvariations. Most of these proteins purified with the nuclearsap or ribosomal components. Key words: Cell proliferation, electrophoresis, Pisum sativum L, root meristems