GROWTH OF NUCLEI IN METHYLXANTHINE INDUCED BINUCLEATE CELLS OFVICIA FABA

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Abstract
Primary roots of V. faba L. were treated with solutions of 2 methylxanthines, 3-isobutyl-1-methylxanthine (IBMX) and 8-ethoxycaffeine (8-EOC). Binucleate cells were formed and, using this marked sub-population, nuclear growth was studied. In a 12-h period of interphase, nuclei did not grow, their mean volume decreased slightly by 5.3% in IBMX induced binucleate cells and by 11.3% in 8-EOC induced binucleate cells. In the next 2 h, nuclear volume increased. By 15-17 h after IBMX treatment, about 75% of the binucleate cells had divided; none of the binucleate cells in 8-EOC treated roots had divided even by 21 h. Mean volume of prophase nuclei was lower in uni- and binucleate cells of IBMX treated roots than in normal roots. Sister nuclei of binucleate cells rarely had identical volumes. The difference between the mean volume of the larger and smaller nucleus of each pair of interphase nuclei ranged from 74.mu.m3 in a sample whose mean nuclear volume was 545 .+-. 131 .mu.m3, to 178 .mu.m3 when mean nuclear volume was 707 .+-. 284 .mu.m3. The mean difference between prophase sister nuclei was 190 .mu.m3 and the overall mean volume was 1320 .+-. 297 .mu.m3. In some way, sister nuclei of binucleate cells are unequal and the mitosis from which they were formed was differential. The results are discussed in terms of nucleo-cytoplasmic interactions.