EFFECTS OF MG2+ AND CO2+ ON CELL-DIVISION AND NUCLEOLAR CYCLE DURING MITOSIS IN ROOT-TIP CELLS OF ALLIUM-CEPA

Effects of Mg2+ and Co2+ on cell division and the nucleolar cycle during mitosis in root tip cells of Allium cepa were studied. The concentrations used of magnesium sulphate and cobaltous nitrate were in the range of 10(-7)-10(-1) M. The results showed that both Mg and Co can, at higher concentration, have a toxic effect on cell division comprising c-mitosis and lagging chromosomes, anaphase bridges, and chromosome stickness. Excessive Mg and Co can also induce some silver-stained particles similar to nucleoli, which are scattered around the chromosome or in the cytoplasm during metaphase and anaphase. The possible mechanism behind this phenomenon is briefly discussed.