engleski

Symbiotic and asymbiotic Chlorella in a toxic environment

The effect of norflurazon on endosymbiotic Chlorella vulgaris Beij. [K&H, 1992] from green hydra (Hydra viridissima Pallas, 1766) and asymbiotic Chlorella kessleri Fott et Novak. [K&H, 1992] was researched on evolutionary and ecotoxicological level. With this work we tried to obtain the information about difference between high-related algae in symbiosis and out of it and to observe the differences of the effect of toxicant upon them. Norflurazon causes the 'bleaching effect' upon the newly developed chloroplasts. Organisms were treated with aqueous solutions of norflurazon (2x10-5, 2x10-6, 2x10-7 mol/L) in glass dishes, and in tubes on deep stock agar for 21 days in the laboratory conditions. Cytological and ultrastructural changes were observed with binocular light microscope and TEM. Of special significance were the antichloroplastal effect and damages to the thylakoidal system, which were increased with the higher concentration of toxicant. Newly developed buds in symbiotic green hydra were not bleached, and therefore neither were endosymbiotic algae. The 'bleaching effect' was present only in algae out of symbiosis, with deleterious effect upon algal chloroplasts. This could suggest that endosymbiotic alga could have some level of resistance to toxicants or could even support the idea that Chlorella from green hydra could present the separate species of algae.

Chlorella; symbiosis; chloroplasts; evolution; ecotoxicology; green hydra

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