Effects of nalidixic acid, chloramphenicol, cycloheximide, and anisomycin on structure and development of plastids and mitochondria in greening Euglena gracilis - Neumann, D.; Parthier, B. (Elsevier)
The substructure of plastids and mitochondria and the alterations caused by the addition of antibiotics were investigated during light-induced proplastid-to-chloroplast transformation in Euglena gracilis. The organisms were grown in presence of the inhibitors up to 3 days (5 generations). Both 40 μg/ml nalidixic acid and 1-1.5 mg/ml chloramphenicol prevent the formation of chloroplasts of normal size and structure by blocking development during early stages. Under our conditions 2 to 5 straight thylakoids are formed beside 1 to 2 girdle-like thylakoids. The former rarely fuse into bands. Non-crystalline prolamellar bodies of considerable size are formed at the distended ends of the plastids in the presence of both drugs. Chloramphenicol also influences mitochondrial size, shape and internal structure. Giant mitochondria can be observed. Nalidixic acid does not change the size and shape of mitochondria, but the matrix frequently appears highly osmiophilic. Cycloheximide in sublethal doses (2-5 μg/ml) or 50 μg/ml anisomycin inhibits plastid development only in the early period after addition. In later culture periods chloroplasts are found enlarged in size with an increased number of thylakoids and bands per organelle. Insertions of new bands are noted at the inner membrane of the chloroplast envelope. The electronmicroscopic observations agree with the results of chloroplast-specific biochemical activities such as light-induced increase in chlorophyll synthesis and of two chloroplast-bound enzyme activities. The results are discussed with respect to metabolic and biogenetic correlations between the two types of organelles in E. gracilis cells.
http://dx.doi.org/10.1016/0014-4827(73)90514-4
Keywords: W; WW-YZ