|
| |
|
| |
|
|
Diversity of noncultivation and difficult cultivation representatives of family Psalteriomonadidae (Excavata: Heterolobosea)
Uhrová, Kristýna ; Čepička, Ivan (advisor) ; Škaloud, Pavel (referee)
Heterolobosea is a group of amoeboflagellates, amoebae, and flagellates belonging to the supergroup Excavata. Approximately 150 species of Heterolobosea have been described, from which less than 20 are obligately anaerobic. Most anaerobic species belong to the family Psalteriomonadidae. The aim of this study was to examine the diversity of potentially uncultivable anaerobic heteroloboseids. We obtained multiple new isolates, mainly from freshwater hypoxic sediments, isolated DNA from fresh cultures and determined their SSU rRNA gene sequences using Psalteriomonadidae-specific primers. In total, we have analyzed sequences of 123 new strains, which represented six already described species of Psalteriomonadidae as well as 16 potentially new ones. However, most of the new species died during the early stages of culture. Our results suggest that a great diversity of uncultivable psalteriomonadids exists in the nature. Key words: diversity, SSU rRNA, Heterolobosea, cultivation, Psalteriomonadidae
|
|
|
Prokaryotic symbionts of free-living anaerobic protists
Poláková, Kateřina ; Čepička, Ivan (advisor) ; Hampl, Vladimír (referee)
Anaerobní prvoci jsou organismy obývající ředí bez přítomnosti kyslíku. Najdeme je anoxických habitatech jako jsou mořské a sladkovodní sedimenty, komunální skládky, nesmíme opomenout zástupce žijící v bachoru přežvýkavců, trávicím traktu švábů a dalších živočichů. Většinou mají anaerobní deriváty mitochondrií, často hydrogenosomy, organely produkující vodík. Metabolismus anaerobních prvoků je ve srovnání s aerobními organismy méně efektivní Časté interakce anaerobních ický my však mohou Symbiózy mezi anaerobními běžné a vznikly u zástupců mnoha anaerobních linií. žít buď endosymbioticky, uvnitř buňky hostitele, nebo ektosymbioticky, na povrchu hostitelské buňky. Dvě ekologicky významné skupiny prokaryot si dokázaly osvojit život symbiotickém vztahu volně žijícími anaerobními prvoky anogenní archebakterie, osídlující hlavně , využívají vodík nické sloučeniny k anu a síran redukující bakterie, žijící hlavně na povrchu buněk, využívají vodík a různé organické sloučeniny k redukci síranu na sulfan. Velmi málo se ví o bližším charakteru těchto vztahů druhové identitě a hostitelské specifitě prokaryotických symbiontů. Další výzkum je nutný pro pochopení fenoménu symbióz v anoxickém světě. Klíčová slova: anaerobní prvoci symbióza anogenní archebakterie síran redukující bakterie
|
|
|
Ecology of microbial communities in the sulfidic ore environments
Falteisek, Lukáš ; Čepička, Ivan (advisor) ; Šabacká, Marie (referee) ; Mandl, Martin (referee)
1 Abstract This thesis is focused on the diversity of microorganisms of prokaryotic type living in the environments, where microbial sulfidic mineral precipitation or decomposition occur. The relationship between the microbial community composition and geochemical processes was examined. To the best of our knowledge, we were the first to analyze microbial communities from gossan and their significance for the ecosystem of a large sulfidic ore deposit. In addition, we compared the microbial assemblies at multiple habitats associated with generation or transformation of acidic mine drainage (AMD) and described niche partitioning among closely related organisms. The unexpectedly variable communities in stalactites growing on the AMD springs were utilized as a model for assessing neutral variability of the microbial communities. They clustered almost randomly even though the environmental conditions corresponded with the localities. This is an important difference of the simple communities from stalactites and the common highly diversified microbial assemblies. The communities found in sediments, soil, and many other complex substrates usually reveal high correlation with their environment. We propose that neutral fluctuations of the community composition are suppressed by averaging multiple physically...
|
|
|
Diversity and evolution of anaerobic Heterolobosea
Pánek, Tomáš ; Čepička, Ivan (advisor) ; Oborník, Miroslav (referee) ; Vávra, Jiří (referee)
9 ABSTRACT This thesis is focused on the phylogeny, diversity, and cell structure of obligately anaerobic Heterolobosea (Excavata: Discoba). Using culture-based approach, we have discovered their hidden species diversity and described 11 new species. Our phylogenetic analyses showed that obligately anaerobic heteroloboseans evolved at least twice independently (Creneidae and Psalteriomonadidae). Psalteriomonadidae is a major anaerobic lineage of Heterolobosea as it includes 16 species and 5 genera. Most psalteriomonadids have acristate mitochondria, although Pseudoharpagon pertyi probably possesses remnants of mitochondrial cristae. Creneidae are represented just by a single species, Creneis carolina, which displays unique cell structure and life cycle. Architecture of its flagellar apparatus is not readily comparable with any other eukaryotes and at least some cytoskeletal elements have undergone unprecedented evolutionary positional changes. Anaerobic heteroloboseans are just rarely detected by environmental, culture-independent approaches. Thus, it is impossible to estimate their real species diversity. Nevertheless, our current data on anaerobic jakobids, another lineage of Discoba, indicates that the culture-based approach is relatively powerful to discover species diversity of anaerobic excavates. In...
|
|
|
Diversity and phylogeny of Archamoebae
Zadrobílková, Eliška ; Čepička, Ivan (advisor) ; Kostka, Martin (referee) ; Valigurová, Andrea (referee)
Members of the group Archamoebae are free-living or endobiotic amoeboid flagellates and amoebae. They live in anoxic or microoxic habitats, and their mitochondria have been reduced. They were originally thought to lack mitochondria and represent one of the earliest eukaryotes. However, this hypothesis has been refuted, and now it is evident that the Archamoebae belongs to the lineage Conosa within the supergroup Amoebozoa, together with aerobic slime molds (Macromycetozoa) and variosean amoebae and flagellates. Relatively simple microtubular cytoskeleton is a characteristic feature of Archamoebae. It consists of a single basal body from which a flagellum arises, lateral root, and microtubular cone. Cytoskeleton of aflagellated genera has been completely reduced. About 350 species names of Archamoebae have been created so far. However, most descriptions were based on inadequate morphological features. The identity of numerous species is uncertain, and many of them are likely synonymous. Another problem is a small amount of available molecular data. During our project, we have substantially improved the dataset of DNA sequences of archamoebae. On the basis of molecular and morphological data, we described 13 new species. We showed that genus Rhizomastix belongs to Archamoebae and displays a new type...
|
|
|
Evolutionary history of Parnassiinae
Kaman, Ondřej ; Čepička, Ivan (advisor) ; Král, David (referee)
This review is devoted to the evolutionary history of the Parnassiinae subfamily of the family Papilionidae and particularly to the nominate genus Parnassius which is the main group among the eight extant Parnassiinae genera. At first, the taxonomic concept, monophyly, and phylogenetic position of Parnassiinae are thoroughly discussed. It is shown that all its genera form three clades that are currently classified as tribes. Further, the estimated time of the divergence of Parnassiinae is given together with the description of all fossil taxa. The subsequent part is entirely focused on Parnassius whose internal phylogeny largely corroborates the traditional classification on eight subgenera, although the phylogenetic relationships among these clades remain mostly unresolved. All the clades are systematically discussed and interesting phylogenetic cases of species complexes and closely related taxa are analysed and supplemented by taxonomic remarks. The last three chapters are dedicated to the phylogeography of P. mnemosyne, P. apollo, and P. phoebus complex. Their evolutionary history is discussed in relation to glacial events in Pleistocene and warming of the climate in Holocene. The whole treatment attempts to integrate morphological, molecular, and biogeographical views together in order to provide a...
|
|
|
Diversity of Blastocystis (Stramenopiles) in reptiles and arthropods
Lorencová, Markéta ; Čepička, Ivan (advisor) ; Jirků, Kateřina (referee)
The genus Blastocystis has recently attracted the attention of scientists, especially parasitologists. Similarly to the related opalines and proteromonads, Blastocystis is anaerobic and lives endobiotically in the intestine of various animals. This organism is also often found in humans, where it is associated with irritable bowel syndrome, though its pathogenic potential remains uncertain. The genus Blastocystis is remarkable for its rich genetic diversity. The taxonomy of Blastocystis is inconsistent and problematic. The strains isolated from homoiothermic vertebrates are divided into 17 subtypes, while strains from poikilotherms are either classified as separate species or are not considered in taxonomic studies at all. The aim of the study was to further examine the genetic diversity of the genus Blastocystis. We determined SSU rDNA sequences of 38 strains isolated from poikilothermic vertebrates and arthropods. The results of our phylogenetic analysis showed that Blastocystis is considerably diverse in these hosts, and we defined 21 new subtypes. The total number of known subtypes of Blastocystis has thus increased to 38. We also examined light-microscopical morphology of some strains. Most of the newly defined subtypes show identical morphology, ST20 (Blastocystis geocheloni) is an exception,...
|
|
|
Diversity of free-living diplomonads
Rmoutilová, Eva ; Čepička, Ivan (advisor) ; Kostka, Martin (referee)
Order Diplomonadida belongs to the supergroup Excavata and comprises both free-living and endobiotic protists. Until recently, research on diplomonads was focused mainly on endobiotic representatives, particularly the parasite Giardia intestinalis, which has been the object of interest of many studies. Diplomonads are anaerobic protists that lack aerobic mitochondria. Instead, they possess reduced mitochodnrial derivates - hydrogenosomes or mitosomes. According to the morphology, the diplomonads are divided into unizoic (single karyomastigont) and diplozoic ones (doubled karyomastigont). Evolution of the cell morphology of diplomonads still remains unclear, and a thorough study focused on free- living diplomonads can help to elucidate this problem. Besides, the diplomonads are interesting because many secondarily free-living representatives of this group exist. This study is focused on the phylogeny a morphology of free-living diplomonads. We determined 65 new SSU rDNA sequences, mainly from free-living diplomands. Phylogenetic analyses showed genera Trepomonas and Hexamita as well as unizoic diplomonads non- monophyletic. Also, several diplomonad lineages containing both free-living and endobiotic species were recovered. We conducted a detailed study of morphology of two genera, Trepomonas and...
|
guest ::
