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Transport of proteins into secondary plastids
Vanclová, Anna ; Hampl, Vladimír (advisor) ; Doležal, Pavel (referee)
Secondary plastids can be found in many unrelated groups of organisms among three supergroups - Excavata, Rhizaria and Chromista. Primary plastids in contrast are unique and defining feature of the Archaeplastida supergroup. Secondary plastids have arisen through several independent endosymbiotic events, in which engulfment of an eukaryotic cell containing primary plastid occured and its reduction and integration by transfering bulk of their genome into host nucleus occured. Crucial difference between primary and secondary plastids is number of surrounding membranes which need to be crossed by nucleus-encoded proteins which is higher in secondary plastids. Mechanisms of protein transport into secondary plastids are therefore more complicated and more molecules and signals partake in these mechanisms. Diversity of secondary plastid-bearing organisms notably contrasts with the fact that the transport pathways and molecules they use often share mechanism of function and origin. These similarities probably reflect general principles of cell biology and not phylogeny.
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Evolution of mastigont in Excavata
Táborský, Petr ; Čepička, Ivan (advisor) ; Hampl, Vladimír (referee)
In recent years we have been discovering a huge diversity of eukaryotic organisms. One of the big super-groups is Excavata. Examination of the organisms from this group is fairly important as far as theoretical and practical reasons are concerned. A significant number of authors believe that there is the root of all eukaryotic organisms in this group. And what is more, a lot of studies prove the point. Within Excavata group we can find the organisms with the most primitive mitochondrial genome which is known. Several other representatives are an important human pathogenes. In the first part of the thesis I focus on the historical review of the creation of the super-group Excavata and I also include a part regarding the theory about Archezoa. The next section deals with the general description of mastigont (basal bodies and cytoskeleton that is associated with them). The last part presents mastigont descriptions of some derived representatives of Excavata. Some of these organisms may be free-living and some live inside other organisms.
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Lateral gene transfer and its utilisation for the phylogeny of eukaryotes
Novák, Lukáš ; Hampl, Vladimír (advisor) ; Čepička, Ivan (referee)
Lateral gene transfer is a relatively rare event in eukaryotes. Presence of a specific gene acquired by lateral transfer in multiple lineages can be therefore considered to be their common synapomorphy, defining them as a monophyletic group. In contrast to usual phylogenetic methods, this approach can potentially shed light even on the direction of evolution and therefore find the position of a root of a given group of organisms. In the first part of this work I discuss various aspects of lateral gene transfer utilisation in eukaryote phylogeny including advantages and disadvantages against common approaches. In the second part I present particular studies that have recently used this method. Key words: Lateral gene transfer, rare genomic changes, long branch attraction artefact, endosymbiosis, phylogeny, eukaryots, protists.
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Cryptic diversity of free-living trichomonads and their phylogenetic position within Parabasalia
Céza, Vít ; Čepička, Ivan (advisor) ; Hampl, Vladimír (referee)
Trichomonads (Parabasalia) are anaerobic microeukaryotes classified in the supergroup Excavata. Inclusion of parabasalids within Excavata is exclusively based on the molecular- phylogenetic evidence. Over 400 species of parabasalids have been described so far, and the vast majority of them are endobiotic. In contrast, only few species of free-living parabasalids forming four independent lineages have been described (Pseudotrichomonas keilini, Ditrichomonas honigbergii, Monotrichomonas carabina, Honigbergiella sp., Tetratrichomonas undula, and Lacusteria cypriaca). Lacusteria cypriaca is a new species and genus described in our recent paper. In this paper we published the first two sequences of SSU rDNA from Pseudotrichomonas keilini as well. All of these lineages are likely secondarily free-living, and they developed from endobiotic ancestors. In addition to the already published Lacusteria cypriaca and Pseudotrichomonas keilini strains, we have recently obtained seven another isolates of free-living trichomonads (LAGOS2D, E2NT, CK, LAGOS2M, GR8, GOU23 LIVADIAN, and VAV1A1); from all of these isolates we sequenced SSU rDNA and performed phylogenetic analyses. These isolates split into four independent evolutionary lineages, which indicate that free-living parabasalids are more diversed and...
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Molecular phylogenetics and geometric morphometrics of aerophytic green algae of Coccomyxa/Pseudococcomyxa s.l. complex
Nemjová, Katarína ; Neustupa, Jiří (advisor) ; Hampl, Vladimír (referee)
This thesis deals with molecular diversity and shape variation of the traditionally delimited unicellular coccoid genera Coccomyxa SCHMIDLE and Pseudococcomyxa KORŠIKOV (Trebouxiophyceae, Viridiplantae). The complex of these traditional genera was found monophyletic position within the class Trebouxiophyceae on the basis of 18S rDNA sequences. Subdivision of this lineage into individual clades was based on 18S rDNA, ITS1 and ITS2 sequences. The results did not confirm delimitation of traditional genera. However, they suggest ecological differentiation of individual clades. The results of phylogenetic analyses were further supported by reconstructions of ITS2 secondary structures and analyses of the compensatory base changes (CBC) among individual clades. The mutual relationships among clades remained, however, partially unclear. Geometric morphometric variation of cell shapes illustrated pattern that was mostly not correlated with molecular data. This indicates high degree of evolutionary plasticity and possible unreliability of these morphological features in taxonomy of the group. Powered by TCPDF (www.tcpdf.org)
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The essential processes of FeS cluster assembly and mitochondrial protein import in parasitic protists
Šmíd, Ondřej ; Tachezy, Jan (advisor) ; Hampl, Vladimír (referee) ; DYALL, Sabrina D. (referee)
CONCLUSIONS Mitochondria appear to be vital organelles for all eukaryotic organisms known to date. A large body of evidence strongly indicates that hydrogenosomes and mitosomes, the organelles of anaerobic or intracellular parasitic protists lacking the "typical" mitochondria, are only a variation on the mitochondrial theme. However, even though the three organelles are evolutionarily the same entity, remarkable differences exist between them that reflect the adaptation of the organisms to their specific niches. In the thesis I tried to unravel some aspects of the essential mitochondrial processes of FeS cluster assembly and mitochondrial protein import in parasitic protists T. brucei and G. intestinalis. We investigated the function of the T. brucei cysteine desulfurase IscS and the scaffold protein IscU. We demonstrated that the two proteins are essential for FeS cluster formation and consequently the viability of the procyclic stage of T. brucei. Even though both IscS and IscU were specifically localized to the mitochondrion, their deficient expression affected the maturation of FeS proteins operating not only in the mitochondrion, but also in the cytosol. This indicates that a crucial part of FeS cluster assembly is localized to the mitochondrion of T. brucei. One of the major differences between the T....
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