Effects of some inhibitors of protein synthesis on the chloroplast fine structure, CO2 fixation and the Hill reaction activity

A comparative study concerning the effects of chloramphenicol (100 μg ml-1, actidione (10 μg ml-1), 5-bromouracil (190 μg ml-1), actinomycin D (30 μg ml-1) and DL-ethionine (800 μg ml-1) on the chloroplast fine structure, 14CO2 incorporation and the Hill reaction activity was the subject of the experiments presented in this paper. The experiments were conducted on bean seedlings under the conditions when chlorophyll accumulation was inhibited only partially. The results obtained indicate that chloromphenicol is responsible for the reduction of the number of grana per section of plastid and for the formation of numerous vesicles in the stroma. In the presence of actidione, actinomycin D or DL-ethionine the lamellae are poorly differentiated into .stroma and granum regions and there occur disturbances in the typical orientation of lamellae within chloroplasts. Only in the presence of 5-bromouracil the development of chloroplast structure resemble that in control plants. A comparison of the results obtained with those published earlier (Więckowski et al., 1974; Ficek and Więckowski, 1974) shows that such processes as assimilatory pigment accumulation, the rate of CO2 fixation, the Hill reaction activity, and the development of lamellar system are suppressed in a different extent by the inhibitors used.