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

Effects of Mg2+ and Co2+ on cell division and the nucleolar cycle duri ng mitosis in root tip cells of Allium cepa were studied. The concentr ations used of magnesium sulphate and cobaltous nitrate were in the ra nge 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 s tickness. Excessive Mg and Co can also induce some silver-stained part icles similar to nucleoli, which are scattered around the chromosome o r in the cytoplasm during metaphase and anaphase. The possible mechani sm behind this phenomenon is briefly discussed.