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Morphological, ultrastructural, and molecular characterization of novel isolates of Anaeramoeba (Metamonada: Anaeramoebae)
Pavlátová, Magdaléna ; Čepička, Ivan (advisor) ; Kolísko, Martin (referee)
Anaeramoebae is a phylum of anaerobic marine amoebae and amoeboflagellates that belongs to the Metamonada supergroup. To date, this phylum has been represented by only six free- living species belonging to a single genus, Anaeramoeba. In this study five isolates with amoeboid stage of the genus Anaeramoeba were morphologically characterized, one on which also contained a flagellate stage. The ultrastructure of three isolates was investigated. Prokaryotes are in symbiotic relationships with all known members of the genus Anaeramoeba and our results show that these symbionts occur in three different arrangements within host cells. Furthermore, the distance between the nucleus and the acentriolar centrosome was studied and found to vary between species. The 18S rRNA gene sequences were obtained from three isolates and were included with previously sequenced strains in a phylogenetic analysis. In the remaining two isolates 18S rRNA gene sequencing was unsuccessful, but morphological and ultrastructural features support a relationship of these isolates to A. ignava. Phylogenetic analyse revealed that one of the isolates based on its sequence belongs to the A. flamelloides complex and two of the of the isolates represent a new species of the genus Anaeramoeba having the smallest cells of all known...
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Loss of excavate features in Excavata
Pavlátová, Magdaléna ; Čepička, Ivan (advisor) ; Němcová, Yvonne (referee)
Excavata is a supergroup of protists belonging to the Eukaryota domain. It is a very diverse taxon that comprises free-living organisms, commensals, and also parasits of animals and humans. Excavata is divided into two main lineages, Metamonada and Discoba, but from the morphological point of view the group Malawimonadida should belong here as well. The internal relationships as well as the monophyly of excavates have not been satisfactorily elucidated yet. The last common ancestor of excavates, perhaps even of all eukaryotes, had a ventral feeding groove, which was associated with a recurrent flagellum. This organism also possessed certain cytoskeletal structures that supported the ventral groove and vanes on the recurrent flagellum. These features have been preserved in some excavates to this day. However, the ventral groove has been reduced or lost in many lineages during the evolution and these representatives, which I refer to as non-excavate excavates, prevail. The aim of this thesis is to describe the ultrastructure of particular lineages of non-excavate excavates and to compare their cytoskeletal system with the cytoskeleton of typical excavates. The loss of excavate features in these lineages is discussed. Key words: excavate, non-excavate excavate, typical excavate, ultrastructure,...
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