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The aim of this paper was to evaluate whether symbiotic cooperation between green hydra (Hydra viridissima) and photoautotrophic alga gives higher resistance of the preservation of DNA integrity compared to brown hydra (Hydra oligactis). Norflurazon concentrations were 0.061 or 0.61 mg/L and UV-B light 254 nm, 0.023mWcm− 2 applied separately or simultaneously. By alkaline comet assay primary DNA damage was assessed and cytotoxicity by fluorescent staining. Norflurazon at 0.61 mg L− 1 significantly increased DNA damage in brown hydras compared to the control (6.17 ± 0.6 μm, 5.2 ± 1.7% vs. 2.9 ± 0.2 μm, 1.2 ± 0.2%). Cytotoxicity was significantly elevated, being higher in brown hydras (25.7 ± 3.5% vs. 8.2 ± 0.2%). UV-B irradiation induced significant DNA damage in brown hydras (13.5 ± 1.0 μm, 4.1 ± 1.0%). Simultaneous exposure to UV-B and norflurazon led to a synergistic DNA damaging. The frequency of cytotoxicity and hedgehog nucleoids was more pronounced in brown (78.3 ± 9.4%; 56.4 ± 6.0%) than in green hydras (34.7 ± 2.5%; 24.2 ± 0.6%). Evolutionary established symbiotic cooperation proved to provide resistance against cyto/genotoxicity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The novel program for graphical display and editing of molecular systems, luscus, is described. The program allows fast and easy building and/or editing different molecular structures, up to several thousands of atoms large. Luscus is able to visualise dipole moments, normal modes, molecular orbitals, electron densities and electrostatic potentials. In addition, simple geometrical objects can be rendered in order to reveal a geometrical feature or a physical quantity. The program is developed as a graphical interface for the MOLCAS program package, however its adaptive nature makes possible to use luscus with other computational program packages and chemical formats. All data files are opened via simple plug-ins which makes easy to implement a new file format in luscus. The easiness of editing molecular geometries makes luscus suitable for teaching students chemical concepts and molecular modelling. [ABSTRACT FROM AUTHOR]

A series of N,N'-disubstituted 3,4-ethylenedioxythiophene-2,5-dicarboxamides was synthesised by amide bond formation between 3,4-ethylenedioxythiophene-2,5-dicarbonyl chloride and corresponding primary amines, where the size and the nature of the substituent were varied. The crystal structures of prepared compounds were determined by X-ray structure analysis. Mechanism and reaction rates of interconversion between conformational isomers were obtained by DFT calculations. All studied compounds reveal axial chirality with molecular symmetry C. Amide bond isomerisation and twisting of the dioxane ring in studied compounds results in the formation of series of conformers of which the s- trans/ s- trans conformer is energetically most favourable. [ABSTRACT FROM AUTHOR]

Symbiotic associations are of a wide significance in evolution and biodiversity. Green hydra is a typical example of endosymbiosis. In its gastrodermal myoepithelial cells, it harbors individuals of unicellular green algae. Morphological characteristics of isolated algae determined by light and electron microscopy are presented. Cytological morphometric parameters (cell area, cell radius, chloroplast area) of isolated algae from green hydra (Cx), as well as from reference species Chlorella kessleri (Ck) and Chlorella vulgaris (Cv), revealed similarity between the isolated endosymbiont and C. kessleri. Isoenzyme patterns of esterase (EST), peroxidase (POX), and catalase (CAT) were used for the investigation of genetic variability in endosymbiotic algae isolated from green hydra. Out of 14 EST isoenzymes observed in Cx species, 9 were expressed in the Cx sample. Results of the EST isoenzyme analysis indicated a higher degree of similarity between Cx and Cv than between Cx and Ck. Due to much higher heterogeneity, EST isoenzymes seem to be more suitable genetic markers for identification of different Chlorella species than CAT and POX isoenzymes. Results obtained suggest that symbiogenesis in green hydra has probably not been terminated yet. [ABSTRACT FROM AUTHOR]

The effect of aluminium on histopathological and behavioral changes in the planarian Polycelis felina (Daly.) in laboratory conditions was studied. The planarians were treated with seven concentrations of aluminium sulfate for five days and compared to three control groups of animals. Microscopical, histological and morphometric methods were used. The results showed distinguished morphological changes on the planarian body as well as behavioral changes: various depigmentations, disordered locomotion, twisting of the body parts, hardly reacting to the mechanical stimuli, body contractions, deformations and mortality. Histomorphometric analyses showed changes in the size and number of neoblasts and reticular cells. Changes in epithelial cells and segments, parenchyma and muscular layer were also noticed. Concentrations of 600 and 1100 mg/L caused most distinct changes in behavior, morphological and histological structure of planarians. The highest concentrations caused irreversible changes. Considering high LC50 (1100 mg/L), the used concentrations of aluminium presented no actual environmental threat to planarian populations in nature, but showed the extent of damages in a possible concentrated aluminium environment. [ABSTRACT FROM AUTHOR]