engleski

Endosymbiotic green algae in European Hydra strains show quantitative difference on morphological and isoenzyme level

The process of endosymbiosis is one of the promoters of speciation. The green hydra (Hydra viridissima Pallas, 1766) is a typical example of endosymbiosis. Its gastrodermal myoepithelial cells harbour the individuals of unicellular photoautotrophic algae. In this study we have developed healthy laboratory cultures of endosymbiotic green algae isolated from green hydra strains. The Hydra strains were collected from four different geographical localities, two of which were in Croatia (strains BV, T), one in Israel (strain M9) and one in Germany (strain HV). For the first time, endosymbiotic algae isolated from green hydra strains have been visualized and described by scanning and transmission electron microscopy. Isolated endosymbiotic algae were characterized by cytological morphometric parameters, enzyme activity and isoenzyme pattern analysis (catalase, peroxidase and esterase). In addition, cells of endosymbiotic algae were characterized by morphometric measurements of diameter, perimeter and area, and chloroplast area. Endosymbiotic algae HV (collected in Germany) and M9 (collected in Israel) were significantly different when compared with endosymbiotic algae T and BV collected in Croatia. The endosymbionts were more different with referent alga Parachlorella kessleri than with referent alga Chlorella vulgaris. The results obtained by isoenzyme pattern analysis also suggested that there was a difference between Croatian and European algal endosymbionts, i.e. the results indicate biological diversity among algal symbionts isolated from the green hydras from different geographical localities. Ultimately, five isoenzymes of catalase and five isoenzymes of peroxidase were resolved by PAGE electrophoresis. Catalase isoenzyme K1 appeared only in endosymbiotic alga M9 collected in Israel and catalase isoenzyme K3 only in endosymbiotic alga T collected in Croatia. Peroxidase isoenzyme P1 was observed only in endosymbiont HV while peroxidase isoenzyme P5 was observed in both endosymbionts HV and M9. Peroxidase isoenzymes P3 and P4 were visible in endosymbiotic algae BV and T collected in Croatia.

endosymbiotic algae ; green hydra ; symbiosis ; electron microscopy ; isoenzyme analysis ; morphometry

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