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Encystation and life cycle of free living amoebae of the genus Acanthamoeba spp.
Bínová, Eva ; Nohýnková, Eva (advisor) ; Dyková, Iva (referee) ; Ondriska, František (referee)
Amoebae of the genus Acanthamoeba spp. are free-living unicellular organisms found in disparate ecosystems all over the world. Due to their ability to invade human body, evade its defensive mechanisms and cause extensive tissue damage, Acanthamoeba infection can lead to serious, if rare, diseases, affecting most commonly the eye and the central nervous system. Specific therapy for Acanthamoeba infections is not available. A major reason for therapeutic failure in ameobiasis is the ability of the protist to differentiate into resistant stages. These are cysts, known to be formed under prolonged unfavorable conditions, both in the environment and the infected tissues, and the pseudocysts, less durable but rapidly formed under acute stress. The present thesis focuses on as yet unexplored mechanisms of resistance of cysts and pseudocysts. Moreover, further characteristics distinguishing cysts and pseudocysts as well as the processes involved in their formation are investigated. One of the issues addressed is a presence of protective carbohydrate compounds mannitol and trehalose that participate in defensive reactions against abiotic stress in many organisms. Although putative genes for enzymes of the trehalose and mannitol synthetic pathways are present in the genome of Acanthamoeba, only one of the...
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Does the synthesis of sugar alcohols represent a general mechanism of plant stress response?
Peldřimovská, Jitka ; Lipavská, Helena (advisor) ; Zelenková, Sylva (referee)
Plants cope with adverse environmental conditions with broad variety of defence mechanisms. One of them is the accumulation of compatible solutes, e.g. carbohydrates including sugar alcohols. The compatible solutes are involved in osmotic adjustment, scavenging of reactive oxygen species and they can protect macromolecules and cell membranes by simulation of water envelopes. The sugar alcohols appear in a large range of plants where they serve as primary products of photosynthesis and are involved in long distance transport of C and energy storage. Homologues of the enzymes of polyol metabolism, however, have been recently found also in the plant species that do not use sugar alcohols for fulfilling of above mentioned basic functions of carbohydrate metabolism and where their role remains elusive. It is well known that some plants are able to switch between different carbohydrates in response to different stresses, and some produce polyols only at a certain stage of development. It is therefore question of further studies, whether the polyols cannot be observed in other plants under specific stress conditions and in certain developmental stages as a part of stress response. The aim of this Bachelor thesis is to summarize knowledge of mannitol and sorbitol roles, and especially their involvement in...
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