engleski

Effect of calcium chloride and calcium bromide on chloroplasts of Lemna minor L.

Saturated water solutions of CaCl2, CaBr2 and a 1:1 mixture of them are commonly used as "high density brines" for pressure control in oil wells. To investigate the effect of these chemicals on chloroplasts morphology and their sedimentation profile in sucrose gradient, duckweed Lemna minor L. was chosen as a test organism. By light microscopy, round to oval chloroplasts in control plants and in plants grown on media supplemented with 0.025 and 0.050 mol dm-3 of tested salts were observed. However, in the plants grown on media containing higher concentrations of tested salts (0.075 and 0.1 mol dm-3) most of the chloroplasts were of irregular shape and bigger. The sedimentation profile of the control and the treated chloroplasts (based on chlorophyll determination in 200-ml fractions) also differed. Control samples showed three peaks, while treated samples showed an additional peak (fractions 5-8). One of the peaks obtained in treated samples was sharper and more intensive than the peak present at the same position in the control extracts. The results obtained showed changes in chloroplasts morphology and sedimentation profile after treatment with the higher concentrations (0.075 and 0.1 mol dm-3) of the salts tested that could be the consequence of starch accumulation in chloroplasts.

duckweed ; Lemna minor ; calcium chloride ; calcium bromide ; chloroplasts ; starch accumulation

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