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Phylogenetic relations of Myxosporea parasitizing in brackish water fish
DAŇHELOVÁ, Jolana
The bachelor thesis is focused on the phylogenetic relationships of Myxosporea which parasitizes fish from brackish water where freshwater is mixed with saltwater. In this environment, myxozoan parasites from the freswater fish hosts meet the ones from the marine fish. Myxosporea creates two main phylogenetic lineages depending directly on the environment of fish´s hosts. The aim of this thesis is to find out the following: which Myxosporea parasitizes fish living in brackish water, their relationships and to which phylogenetic lineage these myxosporeans belong. The introductory part of the thesis is dedicated to taxonomy of Myxozoa, description of their morphology, lifecycles and phylogenetics. I focused mainly on the Myxosporea from three brackish fish hosts Scathophagus argus, Tetraodon nigroviridis and Tetraodon biocellatus which are imported as aquarium fish to the Czech Republic. DNA of parasites was isolated by fenolchloroform method. A phylogenetic marker SSU rDNA was amplified by PCR method and gained products were visualized using gel electrophoresis. All these methods were carried out at the Biological Center of Science Academy of the Czech Republic, Institute of Parasitology, in the Laboratory of fish protistology in České Budějovice. PCR products were sequenced in a service laboratory SEQme. The phylogenetic trees were constructed in a program Geneious, by the following methods: maximum likelihood, maximum parsimony and the Bayesian inference method. I obtained SSU rDNA sequence of 10 species of Myxosporea which were placed by phylogenetic analysis into the phylogenetic tree of Myxosporea. I found out that brackish fish are parasitized by species of both marine and freshwater lineages of Myxosporea and I confirmed a presence of distantly related myxosporeans in one fish host.
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