Morphofunctional changes in cells of Tetrahymena pyriformis W infusoria under the influence of plant growth regulators — derivatives of pyridine-n-oxide

The aim of the Research. To identify morphological changes in Tetrahymena pyriformis W infusoria under the acute exposure to plant growth regulators (PGR) — derivatives of pyridine-N-oxide and compare them to functional disorders of cells. Materials and Methods. In the research we used the 2-methylpyridine-N-oxide, 2,6-dimethylpyridine-N-oxide and their complexes with organic acids (succinic, maleic) or metal salts (ZnCl2, ZnI 2, CoCl2, MnCl2) (a total of 15 substances), synthesized at the Institute of Bioorganic chemistry and Petrochemistry, NAS, Ukraine. Studies were performed on Tetrahymena pyriformis W infusoria in isotoxic doses — at the level of toxic concentrations — LC50, LC16 and inactive concentrations (LC0). Morphological changes in cells of infusoria were assessed visually with the use of a light microscope. Structural changes in infusoria were compared to functional changes in cells (motor activity and energy state) obtained under the same experiment. Results and Conclusions. It is demonstrated that 2-methylpyridine-N-oxide, 2,6-dimethylpyridine-N-oxide and their complexes with organic acids (succinic, maleic) or metal salts (ZnCl2, ZnI2, CoCl 2, MnCl2) cause functional and morphostructural changes in infusoria, the extent of which depends on the current concentration. Morphostructural changes in infusoria under the influence of the studied PGRs are characterized by a change of shape, growth of the contractile vacuole, vesiculation, damage to the integrity of the cytoplasmic membrane, emission of cytoplasm and structural elements of cells into the nutrient medium. Complexes of methyl derivatives of pyridine-N-oxide with metal salts in the studied concentrations reduce speed and increase energy expenditure on movement, cause changes in behavioural reactions and structure of cells to a greater extent than 2-methylpyridine-N-oxide, 2,6-dimethylpyridine-N-oxide and their complexes with organic acids. Both functional and morphological changes in infusoria are more evident under the influence of studied PGR occurring at concentrations corresponding to LC50. At lower concentrations the changes in the functional activity of infusoria were observed. Comparison of the obtained functional and morphostructural indicators of the state of infusoria shows that complexes of methyl derivatives of Pyridine-N-oxide with metal salts have more toxic effects on infusoria than complexes of methyl derivatives of pyridine-N-oxide with organic acids. Reduced motor activity and an increase in energy consumption per a unit of a path of motion, together with the morphological changes of cell structure, are the indicators of toxicity of xenobiotics for infusoria and criteria for assessing their viability. Key Words: methyl derivatives of Pyridine-N-oxide, Tetrahymena pyriformis W, morphofunctional changes.