Tugaj T. Study of the mode of action of macrocyclic trichothecenes from Dendrodochium toxicum Pidopl. et Bilai

The thesis is dedicated to analysis of some aspects of the mode of inhibitory action of the Dendrodochium toxicum macrocyclic trichothecenes, in relation to the test organisms and model systems. Depending on concentration macrocyclic trichothecenes in rendered both activation and inhibition of the protein and nucleic acid syntheses in the primitive prokaryotic repre-sentative Acholeplasma laidlawii, and inhibition of the syntheses of these compounds in eukaryotic representatives Saccharomyces cerevisiae and Chlorella vulgaris. For the first time it was shown, that studied macrocyclic trichothecenes influ-enced the protein syntheses in yeasts at the stage of transcription, inhibiting the key en-zyme of this stage DNA-dependent RNA-polymerase. Comparative analysis of action of investigated toxins on growth and on synthesis of pigments in chlorella at different conditions was conducted. The total ATP content in cells of chlorella decreased during lightening when studied mycotoxins were applied. The abilit y of investigated toxins to increase the permeability of membranes of sarcoplasma reticulum for ions of calcium was established. Dissipation of the calcium gradient across the membrane due to the mycotoxins was similar to influence of known calcium ionophore A 23187. Keywords: Dendrodochium toxicum , macrocyclic trichothecenes, complex of test-systems, mode of action, polymerase activity.