Cell and nuclear size in Vicia faba roots: changes during germination and in response to levels of ambient water | Cell and nuclear size in Vicia faba roots: changes during germination and in response to levels of ambient water [Broadbeans, cell area, nuclear volumes, nuclear: cell ratio]
1983
Thomas, J.E. | Davidson, D.
Changes in cell and nuclear size were studied in roots of germinating seeds of Vicia faba in order to answer the following questions: (1) When is growth of cells and nuclei initiated? (2) Is the ratio, nucleus: cell size, constant over the first two to three cell cycles, i.e. are nuclear and cell growth closely coordinated or can they vary independently of one another? Answers to these questions should contribute to our knowledge of the relation between cell and nuclear growth and the systems that regulate growth of actively proliferating cells. The results show that mean cell area increased very little during the first cell cycle and then decreased over the subsequent two to three cell cycles, i.e. until roots reached a steady state condition. Nuclei, on the other hand, increased in size from 30 to 50 h after seeds were sown, i.e. when most nuclei were in S or G2 The mean and the range in nuclear volumes reached in the first two mitotic cycles during germination are maintained when root meristems achieve a steady state condition. Thus nuclei maintain a constant mean size over the first few cycles, while cells decrease in size. As a, result of this difference, the ratio, nucleus: cell area, increases over the few first cell cycles from 0·157 to 0·222. The ratio increases in both interphase and prophase cells. Increases in size of cells and nuclei are not absolutely coordinated; this suggests that nuclear and cell growth are, to some extent, regulated independently of each other.
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