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Structure and function of the invasion apparatus of microsporidia
Dohnálek, Vít ; Doležal, Pavel (advisor) ; Vávra, Jiří (referee)
Microsporidia are obligate intracellular parasites that cause significant economic damage and can infect humans. They had evolved highly specialized invasion apparatus that is unique to them. During the invasion the sporoplasm is released from the spore wall and it is transferred to the host cytoplasm through the polar tube. Current research on the invasion apparatus has been focused mainly on the polar tube that is its most prominent structure. Polaroplast and posterior vacuole remain out of the main interest, although they are necessary for the activation and execution of the invasion. If the right combination of environmental factors occurs, the organization of the polaroplast begins to change, the posterior vacuole starts to swell and the polar tube is discharged. Sporoplasm is eventually pushed through the tube into the host cell by growing posterior vacuole. The mechanism has not been explained yet however plenty of theories are trying to explain the germination. This work summarizes current theories and knowledge of structure and function of particular parts of the invasion apparatus. Key words: Microsporidia, invasion, polar tube, intracellular parasitism, germination
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Molekulární charakterizace gregarin flebotomů a jejich interakce s hostitelem
Lantová, Lucie ; Volf, Petr (advisor) ; Vávra, Jiří (referee) ; Warburg, Alon (referee)
Gregarines (Apicomplexa: Gregarinasina) are monoxenous parasites of invertebrates. Those found in sand flies (Diptera: Psychodidae) and mosquitoes (Diptera: Culicidae) used to be considered a single eugregarine genus Ascogregarina. Our phylogenetic analyses of the gregarine SSU rDNA, including newly obtained sequences of three species from sand flies, showed that mosquito and sand fly gregarines are closely related to neogregarines, and most importantly, they form two disparate monophyletic groups. Based on these molecular features, accompanied by biological differences, we established a new genus Psychodiella for the gregarines from sand flies, reserving the genus Ascogregarina for the mosquito gregarines. In the new genus, two new species Psychodiella sergenti from Phlebotomus sergenti and Psychodiella tobbi from Phlebotomus tobbi were described. They differ in the life cycles (sexual development of Ps. sergenti is triggered by a blood meal intake) and morphology of their life stages, mainly oocysts. The susceptibility of five sand fly species to both gregarines showed their strict host specificity, as they were able to fully develop and complete the life cycle only in their natural hosts. The life cycle of Ps. sergenti was studied in detail using various microscopical methods. Oocysts are attached to the...
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Molecular Phylogeny, Biology and Classification of the Microsporidia (Microsporidia,Fungi) According to the Model Groups from Caddis Flies (Insecta, Trichoptera) and Butterflies (Insecta, Lepidoptera).
Hyliš, Miroslav ; Vávra, Jiří (advisor) ; Koudela, Břetislav (referee) ; Weiser, Jaroslav (referee)
RESULTS: Theresultsof thePh.D.thesiscanbesummarizedinto4 thematicareas: l ) screeningand experimentaldataconcemingthe prevalence,genusand speciesdiversíty. hostandtissuespeciťrcityand of ecological. pathofyziologicalcharactersof infectionsand of theirtransmission. 2) classificationandtaxonomystudies 3) resultsofsequencingfollowedby phylogenyanalysis 4) resultsoťcomparativestudybasedon summarizeddata Ad r) T\."enty-fourmicrosporidiafrom Trichopteraand Lepidopteraas well as 5 microsporidiafrom potentialintermediatehosts (Crustacea,Amphipoda) were isolatedand screenedusing light andelectronmicroscopyandmolecularbiologymethods.The screenedorganismsrepresented thefollolving generain theconventionalclassificationof Microsporidia (Canrringand Vávra, 2000)ů,osema(7). Endoreticulatus (3), C1lstosporogenes(2). Thelohania (4), Gurleya (1), Cougourdella(l), Pyrotheca(l), Episeptum(5), Toxoglugea(1),Larssoniella (2),unresolved isolates(2)(thenumberofspeciesexaminedin respectivegenerais givenin parentheses). The publications(l-3) and the abstract(8) reportthe ecologicaland experimentaldataon the prevalence,hostand tissue specificity and transmission of l0 examinedmicrosporidia.The :.';!:rtion(.1)and the abstract (7) describe ecological and experimentaldata on several 'f microsporidiaof theglpsy moth,Lymantria dispar...
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The structure and function of transmembrane proteins ABCG2
Vávra, Jiří ; Mančíková, Andrea (advisor) ; Novotný, Marian (referee)
ABCG2 (ABCP/MXR/BCRP) transporters create homodimers through the plasma membrane. They play an important role in transmembrane transport of a wide spectrum of biological substrates. They are essential for renal, intestinal, placental and haematoencephalic barrier function. In particular they perform an excretory function, protect cells against toxic compounds and xenobiotic cumulation. They are also involved in metabolic regulation of stem cells. This bachelor thesis summarizes information about ABCG2 protein function, their physiological role in humans and other mammals. Keywords: ABCG2, BCRP, membrane transporters, multidrug resistention (MDR), ATP binding cassette family (ABC)
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Diversity and evolution of anaerobic Heterolobosea
Pánek, Tomáš ; Čepička, Ivan (advisor) ; Oborník, Miroslav (referee) ; Vávra, Jiří (referee)
9 ABSTRACT This thesis is focused on the phylogeny, diversity, and cell structure of obligately anaerobic Heterolobosea (Excavata: Discoba). Using culture-based approach, we have discovered their hidden species diversity and described 11 new species. Our phylogenetic analyses showed that obligately anaerobic heteroloboseans evolved at least twice independently (Creneidae and Psalteriomonadidae). Psalteriomonadidae is a major anaerobic lineage of Heterolobosea as it includes 16 species and 5 genera. Most psalteriomonadids have acristate mitochondria, although Pseudoharpagon pertyi probably possesses remnants of mitochondrial cristae. Creneidae are represented just by a single species, Creneis carolina, which displays unique cell structure and life cycle. Architecture of its flagellar apparatus is not readily comparable with any other eukaryotes and at least some cytoskeletal elements have undergone unprecedented evolutionary positional changes. Anaerobic heteroloboseans are just rarely detected by environmental, culture-independent approaches. Thus, it is impossible to estimate their real species diversity. Nevertheless, our current data on anaerobic jakobids, another lineage of Discoba, indicates that the culture-based approach is relatively powerful to discover species diversity of anaerobic excavates. In...
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Porcelain disease in crayfish: biology, impacts and distribution
Jelínková, Tereza ; Balcarová, Eva (advisor) ; Vávra, Jiří (referee)
The porcelain disease is a disease affecting crayfish caused by the microsporidium Thelohania contejeani. This intracellular parasite attacks muscle cells of the host and fills them with spores. This leads to white or opaque colouration of the abdominal muscle of crayfish, which is characteristic for this disease. The parasite gradually attacks more muscle fibers which probably leads to decrease of locomotor activity of affected crayfish and finally may result in their death. T. contejeani at low prevalences does not represent a real danger to crayfish populations and thus it is not as serious threat as crayfish plague. However, it has been associated with several cases of mass mortalities too. This thesis summarizes essential findings about infection by this parasite, analyzes its impacts to the host and factors that can influence transmission and progress of this disease. It also describes a life cycle of T. contejeani, summarizes records of the occurrence of this parasite and evaluates risks which it poses to crayfish populations. Finally, methods used to detect infection are described. Keywords: Thelohania contejeani, porcelain disease, crayfish, microsporidia, parasite, muscle
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Motor driver for aerospace applications
Kolenský, Tomáš ; Vávra, Jiří (referee) ; Kolka, Zdeněk (advisor)
This bachelor thesis deals with electric excitation circuit 28V / 1A for aerospace applications. The proposal involves specifying requirements for power, durability and noise excitation circuit further proposal block trade, power, power and control of the driver circuit. The last part is focused on linking individual blocks into a functional whole.
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Host specificity of pathogens of water fleas of the genus Daphnia
Ružarovská, Jana ; Petrusek, Adam (advisor) ; Vávra, Jiří (referee)
Water fleas of the genus Daphnia are infected by a wide range of parasites with different host range. These parasites are mainly representatives of bacteria, protozoa (group Ichtyosporea), yeasts, microsporidia and oomycetes. Host specificity of these parasites is very different. We can find there those, who infect only one host species, but also those, who infect a lot of host species (also hosts of different subphylums). Antagonistic coevolution is the major driving force for evolution of the parasite-host system. Parasites create on their host negative frequency-dependent selection, that cause a lot of phenomenons such as clonal/isolate specificity of both antagonists, maintenance of genetic polymorphism, decreasing virulence etc. A special group of organisms are epibionts, that live on the surface of their holder. Their specialization manifests as preference of a substrate. This thesis summarizes a current knowledge on the host specificity of chosen parasites of the genus Daphnia and also includes what is known about their life cycles. Key words: Host specificity, specialization, generalist, Daphnia, microsporidia, complex life cycle, epibiont.
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Phylogeny of Archamoebae
Ptáčková, Eliška ; Vávra, Jiří (referee) ; Čepička, Ivan (advisor)
Archamoebae is a small group of anaerobic protists belonging to the eukaryotic supergroup Amoebozoa. Historically, they were regarded as primitively amitochondriate. However, a mitochondrial remnant has been found in some archamoebae. Phylogenetic analyses showed that Archamoebae are closely related to the aerobic slime moulds (Mycetozoa). Trophozoites of archamoebae are amoeboflagellates or aflagellated amoebae. The group includes both parasitic (Entamoeba, Endolimax and, possibly, Endamoeba and Iodamoeba) and free-living (Mastigamoeba, Mastigella, Pelomyxa) genera. The genus Mastigina comprises both endozoic and free-living representatives. Flagellated genera Mastigina, Mastigamoeba, Mastigella and Pelomyxa possess a single basal body associated with a microtubular cone which may or may not be associated with nucleus. The cone is a common feature for Archamoebae and mycetozoan slime moulds. The phylogeny of Archamoebae has not been fully elucidated yet and the taxonomy of free-living representatives is confusing. In the present study, we obtained 42 stable isolates of free-living Archamoebae. We sequenced and analyzed SSU rDNA of 15 of them. The Archamoebae split into five lineages. Based on TEM, we were able to recognize genera Mastigamoeba and Mastigella. The isolate IND8 probably represents a new...
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