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Biodiverzita myxozoí v přehradní nádrži Římov zjištěná analýzou environmentální DNA
BÜRGEROVÁ, Monika
Myxozoans represent a diverse group of microscopic endoparasites primarily infecting fish, including over 2,600 nominal species. Despite the extensive number of described species, their diversity remains still unexplored and underestimated. The detection and surveillance of myxozoan parasites in previously unexamined areas can reveal crucial pathogens linked to fish mortality and discover myxozoans biodiversity. This thesis investigates the parasite diversity in the Římov Reservoir, focusing on myxozoan detection through environmental DNA (eDNA). A comparison of detected diversity at various sites and in different environmental samples across the Římov Reservoir unveiled interesting patterns of read abundance and number of OTUs within each myxozoan clade. This study underscores the importance of eDNA analysis in detecting pathogens and assessing biodiversity in myxozoan parasites.
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Evolutionary Analysis of Cystatins of Early-Emerging Metazoans Reveals a Novel Subtype in Parasitic Cnidarians
KYSLÍK, Jiří
The evolutionary aspects of cystatins are greatly underexplored in early-emerging metazoans. Thus, we surveyed the gene organization, protein architecture, and phylogeny of cystatin homologues mined from 110 genomes and the transcriptomes of 58 basal metazoan species, encompassing free-living and parasite taxa of Porifera, Placozoa, Cnidaria (including Myxozoa), and Ctenophora. We found that the cystatin gene repertoire significantly differs among phyla, with stefins present in most of the investigated lineages but with type 2 cystatins missing in several basal metazoan groups. Similar to liver and intestinal flukes, myxozoan parasites possess atypical stefins with chimeric structure that combine motifs of classical stefins and type 2 cystatins. Other early metazoan taxa regardless of lifestyle have only the classical representation of cystatins and lack multi-domain ones. Our comprehensive phylogenetic analyses revealed that stefins and type 2 cystatins clustered into taxonomically defined clades with multiple independent paralogous groups, which probably arose due to gene duplications. The stefin clade split between the subclades of classical stefins and the atypical stefins of myxozoans and flukes. Atypical stefins represent key evolutionary innovations of the two parasite groups for which their origin might have been linked with ancestral gene chimerization, obligate parasitism, life cycle complexity, genome reduction, and host immunity.
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Cathepsin L of Sphaerospora molnari - localisation, function and diagnostic tools
NECHVILE, Rudolf Lukas
The aim of this thesis was to develop diagnostic and quantitative assays/tools based on western blotting, confocal microscopy and immunogold electron microscopy, as well as flow cytometry, to determine the localisation and potential function of the highly expressed cathepsin L of the myxozoan parasite Sphaerospora molnari (SmolCL) in its fish host, the common carp. Furthermore, a recombinant SmolCL was used in a vaccine trial to estimate its potential for raising antibodies in carp and test their immunoprotective potential towards S. molnari. This thesis provides new methodological tools for research and allows a greater understanding of myxozoan parasite-fish host interactions based on proteolytic enzymes.
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Changes of IgM expression levels in the head kidney of Cyprinus carpio following an infection with Sphareospora molnari
SIERANSKI, Viktor
Sphaerospora molnar is a myxozoan inducing sphaerosporosis in common carp and causing serious damage to secondary lamellae and epithelia of the gills. The understanding of the host immune response against S. molnari as well as other myxozoans is very limited in part due to the unresolved life cycle. The focus of this thesis was the quantification of membrane bound and secretory IgM expression levels in the head kidney over a period of 9 weeks following an intraperitoneal injection of S. molnari blood stages. Significant increases in the expression levels of both IgMs were observed reaching its maximum at 42 days after infection. Two weeks following the infection the first significant increases of secretory IgM were detected.
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Biodiversity of Myxozoa based on extensive screening of fish and environmental samples
LISNEROVÁ, Martina
Myxozoans represent a group of morphologically simplified endoparasites infecting mainly fish, annelid and bryozoan hosts including more than 2,600 nominal species. However, the diversity seems to be unexplored and undervalued. Host searching and invasive dissection is a commonly used method for the identification of myxozoan species diversity. Metabarcoding and amplicon analyses of environmental DNA from sediment, water and soil is developing approach for biodiversity assessment and have been performed in many biological areas to identify the diversity of organisms, communities and populations. Using classical morphological and molecular approaches, we explored the myxozoan diversity in selected areas and host groups. In addition, we propose a new methodological approach for the studying of myxozoan diversity based on environmental DNA from sediment and amplicon sequencing. Illumina Mi-Seq with metabarcoding and newly designed primer sets is suitable for analyzing myxozoan communities without the need to find and capture intermediate or final hosts.
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Bioinformatická a funkční charakterizace taxonomicky omezených genů
KYSLÍK, Jiří
Evolutionary dynamics, generating novel phenotypic traits, embody an essential route to either lineage-specific adaptations or to the creation of endless forms in organisms. Understanding the evolution of such ultimate novelties requires the study of the origin and the role of the functional units in generating unique traits, which represent the taxon-specific genes (TRGs). Myxozoa, the endoparasitic cnidarians, have become a suitable model for the study of evolutionary innovations, with their example of single-celled novelty: polar capsules. This uniquelly evolved structure within the spore stage represents a lineage-specific analogy of cnidarian stinging cells (nematocyst). In Cnidaria, nematocysts contain several uniquely emerged genes, rendering the assembly of this complex structure. The prominent fraction represents minicollagens, extremely shortened structural peptides forming the wall and tubule during the nematocyst development. Unlike in Cnidaria, the role of TRGs such as minicollagens in myxozoan development is unknown. The thesis describes the evolution and functional characterization of minicollagens in Myxozoa. Using the bioinformatics and molecular approaches, we explored the diversity and genomic organization and comprehensively characterized minicollagen gene expressions during myxospore development and localization of minicollagens in the polar capsule.
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Haematological response of common carp \kur{Cyprinus carpio} to experimental infection with blood stages of the myxozoan parasite \kur{Sphaerospora molnari}
TOMANOVÁ, Anna
Sphaerospora molnari is a histozoic endoparasite causing severe inflammation during sporeformation in the gills of common carp. As for other myxozoans, little is known about the host response to early proliferation and multiplication of this parasite in the fish host. This thesis is focused on a controlled infection experiment using S. molnari blood stages and on determining cellular and haematological changes of common carp as a response to infection, over a 9-week period post intraperitoneal injection. The results show a noticeable increase in cellular components of innate immunity 14 dpi and a massive increase in lymphocyte numbers, likely B cells, 21-28 dpi. The data are discussed in relation to parasite infection intensity in various tissues and organs, and they strongly point to the acquisition of specific immunity of common carp to S. molnari resulting in a controlled, low level infection from 49 dpi onwards.
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Malacosporea and Sphaerospora sensu stricto: Myxozoan clades with unique biology and evolution
PATRA, Sneha
The Malacosporea and Sphaerospora sesnsu stricto clade are the two most basal myxozoan clades. While the evolutionary older malacosporeans possess unique features resembling cnidarians, sphaerosporids are known for special developmental features and unique long insertions in the small and large subunits of the ribosomal DNA. This thesis aimed at elucidating the hidden biodiversity, describing special biological traits and tracing the evolutionary history of these two clades based on both, morphological and molecular data. Host-parasite phylogenetic congruence was studied to understand the evolutionary patterns of cospeciation and host switching.
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