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Phylogeny of Archamoebae
Ptáčková, Eliška ; Čepička, Ivan (advisor) ; Vávra, Jiří (referee)
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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Anaerobic peroxisomes in Archamoebae
Le, Tien ; Tachezy, Jan (advisor) ; Michels, Paul A. M. (referee) ; Yurchenko, Vyacheslav (referee)
Peroxisomes and mitochondria play a key role in oxygen metabolism. It was widely accepted that the evolutionary adaptation of eukaryotes to anaerobiosis is reflected by the metabolic reduction of mitochondria, and concomitant loss of peroxisomes. The anaerobic protists Mastigamoeba balamuthi (Mb), Pelomyxa schiedti (Ps), and Entamoeba histolytica (Eh) contradict this paradigm. They possess anaerobic types of mitochondria (hydrogenosomes, mitosomes) but also host "anaerobic peroxisomes". Mb/Ps peroxisomes contain a common set of 13 peroxins (Pexs) that retain the core members of each functional category including components of both PTS1 and PTS2 machinery for matrix protein import. However, Eh peroxisomes harbour a reduced set of 7 known Pexs and lacks several components that are highly conserved among most eukaryotic lineages, including components of PTS2 machinery (Pex7), the RING complex (Pex2/10/12), docking complex (Pex13), and peroxisomal membrane protein import receptor (Pex3). Concerning the functional annotation, no clear biochemical context has been found in these anaerobic peroxisomes. They are diverse in enzymatic contents and are involved in various metabolic reactions, while catalase and typical peroxisomal enzymes of fatty acid beta-oxidation are absent. Mb peroxisomes appear to be involved in...
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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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