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Fungal parasites as a factor affecting the dynamics of microalgal communities
Rosa, Jan ; Šťastný, Jan (advisor) ; Pichrtová, Martina (referee)
This bachelor thesis deals with fungal parasites which are an important factor that affects the dynamics of microalgal communities. Here I sum up the knowledge of parasites especially from Oomycota and Chytridiomycota along with a little focus on other groups. The basic characteristics of these fungal parasites, such as their host specificity and factors that affect their spreading ability between algal hosts, are summarized. The abiotic factors such as light and temperature, which are the most important factors causing epidemic, are mainly discussed. The fungal parasites can change the maximal population size and are able to alter the competitive relationships in microalgal communities. These factors are discussed in individual algal groups. The fungal parasites could be a negative economic player of the bioindustry and their future role in this industry is also discussed. Key words: parasite, host, host specificity, communities dynamics, algae, fungi, phytoplankton
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Interactions between microsporidial parasites and the host cladoceran Daphnia pulex in a simple environment of a forest pond
Krylová, Pavla ; Petrusek, Adam (advisor) ; Hyliš, Miroslav (referee)
Among the most common endoparasites who infected small crustacean Daphnia pulex include microsporidia. These intracellular parasites appear to look like a simple single- celled organisms, but their cell structure and lifecycle prove the opposite. Microsporidia are species-specific. Although they infected most organisms of the animal kingdom, they are not yet sufficiently understood. This theses is inderectly followed up to the studies of waterflea Daphnia longispina and microsporidia Berwaldia schaefernai from the dam reservoirs The aim was to analyze closer microsporidian infection on host Daphnia pulex in a forest pool with simple enviroment, which included monitoring time dynamics of Daphnia population and identification infection caused by microsporidia Berwaldia singularis and yet unknown microsporidia labor-marked "HVH". Laboratory work included determination of zooplankton and parasites, calculation of prevalence, laboratory experiments with transmission of microsporidian infection between healthy and infected flea culture or by isolated spores. Genetic analysis of aquatic invertebrates from the forest pool, especially larvae of mite and mosquitos, helped make closer microsporidian life cycle and hypothesis about secondary hosts, for the presence of pathogen DNA using specific DNA...
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Mosquitoes as hosts and vectors of protozoa transmitted to birds
Fialová, Magdaléna ; Svobodová, Milena (advisor) ; Munclinger, Pavel (referee)
Mosquitoes belong to significant representatives of inscet which are particularly studied due to their ability to transmit pathogens (viruses, bacteria, protozoa, worms) in many cases causing serious illnesses. The hosts of these pathogens can be various animals including birds. In this study I have focused on protozoa (especially Plasmodium and Trypanosoma) transmitted by a mosquito. Concerning trypanosomes the mosquito is one of several possible vectors and up to now there have been named two trypanosomes transmitted by birds, namely Trypanosoma culicavium and Trypanosoma thomasbancrofti. In the case of the genus Plasmodium the mosquito is the only vector and there are many more species of the genus Plasmodium, which mosquito transmits between birds. Key words: vector, mosquito, host, bird, Trypanosoma, Plasmodium, infection
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Visual cues in the coevolution of brood parasite and its hosts
Šulc, Michal ; Honza, Marcel (advisor) ; Fuchs, Roman (referee) ; Samaš, Peter (referee)
Avian brood parasitism is an ideal system for the study of coevolution. Brood parasites and their hosts have developed interesting adaptations during co-evolution allowing them to maximize their fitness. The evolution of these adaptations has a character of an "arms race" where the evolution of one trait in the host is tied with the evolution of another trait in the parasite. In my doctoral thesis, I deal with two of these adaptations: recognition of parasitic eggs by hosts and mimicry of eggs in parasites. Since both these adaptations are influenced by birds' visual system, in all my studies I used an objective method to measure the colour and the modelling of avian visual system that is quite different from the human visual system. For instance, humans in contrast to birds cannot perceive ultraviolet (UV) light. However, this part of spectrum influences behaviour of birds substantially (e.g. courtship or foraging). We found that the hosts of brood parasites can use UV light when recognizing parasitic eggs. However, it seems that this part of spectrum is not the main cue in egg recognition (manuscript 1). Ambient light has also an important impact on colour perception. We determined whether the light conditions in nests influence host responses to alien eggs. The Red Bishop (Euplectes orix) was an ideal...
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Transmission and epidemiology of visceral leishmaniasis
Spitzová, Tatiana ; Volf, Petr (advisor) ; Antoniou, Maria (referee) ; Dujardin, Jean-Claude (referee)
Visceral leishmaniasis (VL) is widespread disease caused by protozoa Leishmania donovani and Leishmania infantum. Human visceral leishmaniasis caused by Le. donovani in India is considered an anthroponosis, however in East Africa, the role of animals as reservoirs remains unclear. The first part of this thesis demonstrated natural Leishmania infection in wild rodents and bats in Ethiopia. Overall, 8.2% rodents and 4.9% bats were positive for Leishmania spp. Subsequent sequencing revealed that 10% of Leishmania-positive rodents were infected by parasites from Le. donovani complex, on the other hand, no Le. donovani DNA was detected in bats. All Le. donovani-positive rodents were captured in the localities of southwest Ethiopia where human VL cases have been reported and potential sand fly vectors occur. Our findings indicate that rodents are likely to play a role in VL transmission in Ethiopia. During blood feeding, sand flies inoculate into the host skin immunogenic salivary proteins which elicit species specific antibody response. Anti-saliva antibodies could be used as a marker of host exposure to sand flies and, in leishmaniasis endemic areas, also as risk markers of Leishmania infection. In order to find out if the domestic animals (dog, goat, cow, and donkey) from north and northwest Ethiopia...
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Transmission and epidemiology of visceral leishmaniasis
Spitzová, Tatiana
Visceral leishmaniasis (VL) is widespread disease caused by protozoa Leishmania donovani and Leishmania infantum. Human visceral leishmaniasis caused by Le. donovani in India is considered an anthroponosis, however in East Africa, the role of animals as reservoirs remains unclear. The first part of this thesis demonstrated natural Leishmania infection in wild rodents and bats in Ethiopia. Overall, 8.2% rodents and 4.9% bats were positive for Leishmania spp. Subsequent sequencing revealed that 10% of Leishmania-positive rodents were infected by parasites from Le. donovani complex, on the other hand, no Le. donovani DNA was detected in bats. All Le. donovani-positive rodents were captured in the localities of southwest Ethiopia where human VL cases have been reported and potential sand fly vectors occur. Our findings indicate that rodents are likely to play a role in VL transmission in Ethiopia. During blood feeding, sand flies inoculate into the host skin immunogenic salivary proteins which elicit species specific antibody response. Anti-saliva antibodies could be used as a marker of host exposure to sand flies and, in leishmaniasis endemic areas, also as risk markers of Leishmania infection. In order to find out if the domestic animals (dog, goat, cow, and donkey) from north and northwest Ethiopia...
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Research of vertebrate-microbiota relationship using germ-free organisms
Kubovčiak, Jan ; Kreisinger, Jakub (advisor) ; Hájková, Petra (referee)
Germ free (axenic) animals are individuals reared under specific conditions preventing their contact with surrounding microorganisms. Some of the features observed in these individuals vary from those observed in naturally colonized counterparts. These differences probably reflect the influence of presence of a complex intestinal microbial population in the intestine, which influences important physiological functions of the host body by various mechanisms. Thus, nature of these differences allows to study relationship of the host, vertebrate in this case and its microbiota, which evolved into a complicated system of interactions providing relatively stable coexistence. Germ free research of this relationship is focused on interactions between microbiota and host's immune system, metabolism, morphology of digestive tract and behavior. This thesis provides summary of research outcomes on previously mentioned topics. Powered by TCPDF (www.tcpdf.org)
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Adaptation mechanism of nematodes for harsh condition survival
Čermáková, Petra ; Vadlejch, Jaroslav (advisor) ; Kyriánová, Iveta Angela (referee)
Adaptation is a complex of mechanisms, thanks to which nematodes can endure unfavourable conditions. These can come from either external or internal environment. Which one would be dominating, depends on the exact lifestyle of a certain nematode e.g. nematodes living in free nature must deal with environmental changes, parasitic ones are influenced by viability of the host, but even in this case we cannot dismiss the role of environment. There is always a mutual bond between the parasite, host, and the environment. Nematodes usually resolve emergency situations in two ways. One way is to adapt to the new conditions so they can grow and reproduce. The other way is to choose an adaptation mechanism thanks to which nematodes will survive a threat temporarily. Adaptation mechanisms can vary between individual species or various stages of the same kind of nematodes. Universal adaptation behaviour among nematodes does not exist. Adaptation mechanisms of nematodes cause changes in their physiology, metabolism, morphology, development or growth, but also in their behaviour. The aim of this thesis is to gather information from academic literature and scientific articles and provide a closer description of nematodes and their most usual and important adaptation mechanisms. This is preceded by a general description of nematode biology for better understanding of the issue. Based on this information we can comprehend why nematodes are such a successful phylum. Nematodes can be also considered as pests having a negative impact on the economic and social sphere. Further knowledge of nematodes and their mechanisms of adaptation and exploration of their surprisingly resistant forms can lead to control their regulation.
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Transfer of genetic information between parasite and its host
Soukal, Petr ; Hampl, Vladimír (advisor) ; Votýpka, Jan (referee)
Horizontal gene transfer (HGT) is considered a rare evolutionary event. It can take place between unrelated organisms that coexist in an intimate symbiotic relationship. Such relationship have some parasites with its host. HGT between eukaryotic parasite and its host was identified in some holoparazitic and hemiparazitic plants, the most important human protozoan parasites, microsporidias, human blood-flukes, parasitoids and fruit flies.
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Evolution of molecular interaction between host and parasite
Bílková, Barbora ; Vinkler, Michal (advisor) ; Synek, Petr (referee)
Coevolution between host and parasite is a long-term object of scientific interest, mostly because of negative influence of parasites and human need to defend against it., The evidence concerning host-parasite coevolution mechanisms is, however, still incomplete and various models and theories are considered separately, out of the general concept. Beside generally well-known theories such as the "Red queen" theory or the coevolution "arms race" theory, several other models were proposed, e.g. the "gene for gene" model or the "matching allele" model, which describe detailed aspects of host-parasite coevolution and principles of genetic variability maintenance in their interaction. Although there are many studies mapping reciprocal evolution of hosts and parasites, the connection between empirical evidence and theoretical models is often missing. Therefore, this thesis covers theory on host-parasite evolutionary interactions and provides examples of host-parasite systems and molecules, which correspond to behavior of described models.
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