Neomycin is an aminoglycoside with a bactericidal action against many gram-negative bacteria. Aminoglycosides are taken up into sensitive bacteria by an active transport process. In the cell they bind to 30S and to some extent 50S subunits of the bacteria ribosome, inhibiting protein synthesis and generating errors in the transcription of the genetic code. Chlamydomonas reinhardtii cells shed their flagella in response to environmental stress such as low PH or presence of mastoparan. Under favourable conditions, flagella are quickly grown. During an experiment to regenerate flagella in chlamydomanas, addition of neomycin (an inhibitor of phospholipase C) before of exposure of cells to low pH or mostoparan prevented the increase in Inositol 1,4,5-trisphosphate and also prevented deflagellation. Adding neomycin following deflagallation stopped the increase of Inositol 1,4,5-trisphosphate, which usually followed deflagellation without blocking flagellar assembly. Studies have shown that, although Ins(1,4,5)P3 accumulates to high levels after deflagellation, experiments with neomycin suggest that this accumulation many not be necessary for normal flagellar regeneration. (Quarmby et al, (1992).
Actinomycin D is a chemotherapy drug which is used to treat certain types of cancer. Amoeba-flagellate transformation which occurs in the true slime moulds and in some soil amoeba like Naegleria gruberi involves not only organellar growth but also differentiation of amoeba into new morphological type. Flagellum morphogenesis in N.gruberi is blocked early during incubation by the presence of actinomycin D, suggesting that induction of morphogeneis in this system requires RNA synthesis. Actinomycin inhibits transition during protein synthesis which is necessary for flagellar regrowth, thus if applied to the flagella of chlamydomonas reinhardtii it would inhibit growth (Fulton and Walsh, 1980).
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References
Quarmby, L. M., Yueh, Y. G., Cheshire, J. L., Keller, L. R., Snell, W. J., & Crain, R. C. (1992). Inositol phospholipid metabolism may trigger flagellar excision in Chlamydomonas reinhardtii. The Journal of Cell Biology , 116 (3), 737-744.
Fulton, C., & Walsh, C. (1980). Cell differentiation and flagellar elongation
in Naegleria gruberi. Dependence on transcription and translation. The Journal of cell biology , 85 (2), 346-360.
