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Vliv teploty a času na excystaci Cryptosporidium muris izolát CAT21
DUDÁKOVÁ, Hana
The main aim of this master's thesis was to investigate the impact of environmental pH and the host's body temperature on the excystation of Cryptosporidium muris oocysts. The experiment utilized the CAT21 isolate obtained from a naturally infected domestic cat (Felis catus f. domestica), although rodents are the primary hosts of Cryptosporidium muris. The isolate was continuously maintained in immunodefi-cient SCID mice, from which fecal samples were regularly collected for individual experiments. The first factor examined for its influence on oocyst excystation was the host's body temperature. Oocysts stored in dH2O were subjected to water baths set to temperatures ranging from 21 to 44°C for durations of 5, 15 and 30 minutes. According to the results, the optimal temperature for excystation of C. muris CAT21 oocysts was 37°C for a duration of 30 minutes, resulting in up to 92% excystation. Additionally, the study included an examination of the pH impact on excystation. Oocysts were exposed to PBS solutions with varying pH values (ranging from 2.00 to 9.00) and heated in a water bath at 37°C. The optimal pH for excystation was found to be 6.00, with up to 93% excystation observed. The viability of the oocysts used was determined by staining with propidium iodide before each measurement.
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Infektivita sporozoitů kryptosporidií s ohledem na lokalizaci vývojového cyklu
SKLENÁŘOVÁ, Eliška
Cryptosporidium, belonging to the phylum Apicomplexa, are parasites found across all classes of vertebrates worldwide, including humans. They infect the gastrointes-tinal tract, leading to acute or chronic diarrheal disease, especially in individuals with weakened immune systems. Infection spreads through contaminated water, food, or direct contact. A main aspect is the excystation process, which allows the parasites to infect the host. The study focuses on the environmental conditions of the gastrointestinal tract where Cryptosporidium excystation occurs and the factors ne-cessary for this process. Research has shown that different species of Cryptosporidi-um exhibit variability in excystation depending on their location in the host's body. The results suggest that different species of Cryptosporidium excyst most efficiently in different parts of the digestive tract, thus proper excystation localization is crucial for successful infection. Experiments have shown that environmental temperature and pH play a key role. Research indicates the existence of a protective factor in the host's body that limits excystation in the digestive tract. The study also examines the prepatent period of individual Cryptosporidium species and finds that the method of inoculation does not affect the length of this period. Understanding the excystation process and the conditions that influence it is crucial for the development of effecti-ve cryptosporidiosis therapy.
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Faktory ovlivňující excystaci žaludečních kryptosporidií hlodavců
SCHULZOVÁ, Tereza
The aim of this study was to determine the effect of host body temperature and en-vironmental pH on the excystation and preservation of the ability to infection of rodent gastric cryptosporidia oocysts. The infectivity of unexcysted oocysts was further examined. Immunodeficiency SCID mice (Mus musculus) were infected with C. proliferans oocysts, then their faeces were collected and individual experi-ments were performed. The effect of temperature on excystation, when oocysts were placed in water baths at the appropriate temperature (32-44 °C) and the effect of pH, when oocysts were exposed to solutions of different pH (2-7), was investi-gated. Cell separation was then performed using a flow cytometer and the values obtained were recorded in the tables. The most oocysts excysted at 40 °C and pH 7. An autopsy of infected mice was also performed to determine the infectivity of oo-cysts from various parts of the digestive system. All taken oocyst samples were infectious for the subsequent host. Infection experiments, which were further car-ried out revealed, that unexcysted oocysts exposed to hypochlorite and laboratory temperatures retain their ability to infect. In contrast, the oocyst sporozoites that excysted were susceptible to both hypochlorite and room temperature, thus losing the ability infect the subsequent host.
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Faktory ovlivňující excystaci žaludečních kryptosporidií přežvýkavců
DUDÁKOVÁ, Hana
In this study, we investigated the effects of temperature and pH on the excystation of gastric Cryptosporidium of mammals. Oocysts of Cryptosporiidum andersoni, obtained from a naturally infected cow, were used in this study. Oocyst viability was de termined by propidium iodide staining (PI). The first factor studied was temperature. Oocysts stored in dH2O were incubated in water bath preheated to temperatures between 32 and 44 °C for 5, 15, and 30 min. With increasing temperature and time, we observed a higher percentage of excysted oocysts. Most oocysts excysted at 40 °C and heating for 30 minutes. In addition, excystation of oocysts was also examined in solutions with different pH values (in a range of 29) heated in a water bath at 40 °C. The optimal pH for excysting is between 6 and 7; however, even at lower values, enough oocysts excyst to cause infection.
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Chrysophyte stomatocysts - encystation and excystation dynamics - bentic resting stages of chrysophytes
Mušálková, Petra ; Němcová, Yvonne (advisor) ; Juráň, Josef (referee)
The resting resistant stage has several important roles for phytoplankton microorganisms. It protects them from hostile conditions, allows them to spread to new locations and is often part of their life cycle. Chrysophytes form large populations for only a short part of the year, and therefore the formation of a resting stage is key for them to re-establish a vegetative population the following year. Chrysophyte resting stages are called stomatocysts, which are silicified and have a unique species-specific morphology. They can be form after both sexual and asexual reproduction. This is an understudied area. Most described stomatocysts are not assigned to species and much is not known about the triggers of encystation and excystation. It is thought that a combination of external (temperature, light, nutrients) and internal (cell age and cell concentration) factors are involved. So far, only sexual encystation in Dinobryon cyindricum and Synura petersenii has been studied in detail. My diploma thesis is based on laboratory experiments with Ochromonas tuberculata, Synura uvella and two strains of Synura petersenii. The aim of the study was to investigating whether external conditions such as temperature and lack of nitrogen or phosphorus have the effect on asexual encystation and whether it is...
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Adaptive functions of algal resting stages with emphasis on the chrysophyte stomatocysts
Mušálková, Petra ; Němcová, Yvonne (advisor) ; Pusztai, Martin (referee)
Formation of resting stages is a very common feature occurring in most algae classes. Primarily this stage is considered as a resistant form that helps the organism to survive adverse conditions and rapidly changing environment. However, it may also serve to spread as a seed bank to recolonize habitat or can be a source of genetic variation if it follows sexual reproduction. The importance of this dormant benthic stage grows with algae whose population growth is seasonal and the formation of cysts or spores is crucial for them, for instance dinoflagellates and golden algae. Resting stages of Chrysophyceae are called stomatocysts they are produced endogenously and are composed of polymerized silica. Stomatocysts have species-specific morphology. For most described species of Chrysophyceae morphology of the stomatocyst is unknown. Determining the species is difficult especially because of rapid alternation of chrysophyte dominant species in natural waterbodies. So far, it has not been elucidated what factors cause encystation and excystation. Several laboratory experiments has been conducted on this subject. The process of encystation and excystation is assumed to be induced by combination of external and internal factors. Stomatocysts may developed after sexual reproduction or from vegetative cells....
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