engleski

Isolated endosymbiotic algae at test: the point of no return?

It is well known that evolutionary changes in organisms are not limited to the vertical exchange of genes: a transfer of new genetic characteristics from one species to another is possible as a horizontal gene transfer. Symbiosis, denoting close and often long-term interaction between at least two species, is possibly the best way to achieve such a horizontal gene transfer. The aim of this work was to research advantages or disadvantages of releasing from the hydraalga symbiotic relationship using Chlorella test with iron. The test was performed on endosymbiotic algae Desmodesmus subspicatus (Chodat) Hegewald and Mychonastes homosphaera (Skuja) Kalina and Punčochářová (Chlorella zagrebiensis group Kovac. and Jelen.) isolated from green hydra host (Hydra viridissima Pallas, 1766) and on related freeliving species Chlorella kessleri Fott and Novák. [K&H, 1992] strain LARG/1and C. vulgaris Beij. [K&H, 1992] strain SAG 211 - 11b. The results were observed macroscopically and microscopically in relation to various parameters. Isolated endosymbiotic algae showed a higher sensitivity to iron than the free-living relatives. Increasing concentration of iron led to deformations of cells and cell formations. Among others, empty cells, disturbed divisions and reduced intensity of green color in both isolated species were observed. Isolated species were less able to defend against the toxicity of iron possibly due to a transfer of some of their genetic material to the genome of their Hydra host. Mutualistic symbiotic lifestyle gives a greater chance of survival in the unfavorable (micro-)environment, but after having lost that advantage the symbiotic partners could become more vulnerable. Mutualistic symbiotic lifestyle gives a greater chance of survival in the unfavorable (micro-)environment, but after having lost that advantage the symbiotic partners could become more vulnerable.

endosymbiotic algae ; green hydra ; Chlorella test ; morphometry ; iron

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