National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Teplotní adaptace trávicích enzymů želvušek žijících v trvale chladném prostředí
JOZIĆ, Nikola
This thesis presents a literature review of the phylum Tardigrada, exploring the impact of cold temperatures on living organisms in general and focusing on adaptations of organisms to cold and freezing, particularly in terms of enzymatic adaptations. The experimental part of this work involves comparing the enzymatic activity of the -glucosidase enzyme in tardigrades from Arctic glacier (Svalbard) and soil tardigrades from a temperate climate (Czech Republic) at different temperatures. The results showed higher enzymatic activity in tardigrades from a temperate climate at all measured temperatures, suggesting that the enzymes of glacier dwelling tardigrades are not cold adapted.
Storage cells and their role in tardigrade physiology.
Czerneková, Michaela ; Svoboda, Petr (advisor) ; Delagoutte, Emmanuelle (referee) ; Weyda, František (referee)
STORAGE CELLS AND THEIR ROLE IN TARDIGRADE PHYSIOLOGY Abstract Tardigrades possess remarkable tolerance to numerous stress conditions (e.g. almost complete desiccation, exposure to very low sub-zero temperature, heat stress and even exposure to space in low Earth orbit). Indeed, they are among the most radiation-resistant multi-cellular organisms. The body cavity of tardigrades is filled with the storage cells (SC). Their role in anhydrobiosis has been discussed. The main objectives of this work were to analyse (i) the occurrence of mitosis in SC, (ii) the factors constraining anhydrobiotic survival, and (iii) the general ultrastructure of SC and their ultrastructure concerning the stress conditions. Our model species, R. cf. coronifer is one of the most extensively studied tardigrades concerning anhydrobiosis. Comprehensive histochemical techniques were used in combination with SEM, TEM, and confocal microscopy. First, mitotic divisions of tardigrade SC occur with a higher frequency in juveniles than in adults and correlate with animal growth. Mitosis is more frequent in moulting tardigrades, but the overall mitotic index is low. Furthermore, tardigrades of R. cf. coronifer can survive the maximum of 6 repeated desiccation cycles with significantly declining survival rate with repeated desiccations and...

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