Vladimir Hampl

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Circumscribing major eukaryote groups and resolving higher order relationships between them are among the most chal- lenging tasks facing molecular evolutionists. Recently, evidence suggesting a new supergroup (the Excavata) comprising a wide array of flagellates has been collected. This group consists of diplomonads, retortamonads, Carpediemonas, heteroloboseans, Trimastix, jakobids, and Malawimonas, all of which possess a particular type of ventral feeding

... Protero-monas, the commensal of urodelans, lizards, and rodents, has two flagella, whereas Karotomorpha, the commensal of frogs and other amphibians, has four flagella. The surface of the cell is folded, the folds are supported by single microtubules (Proteromonas) or by ...

We studied morphological and molecular polymorphism of 53 Tetratrichomonas isolates obtained from amphibian, reptilian, mammalian hosts, and from a slug with the aid of protargol staining and analyses of ITS1-5.8S rRNA-ITS2, SSU rRNA, and α-tubulin gene sequences. The phylogenetic tree based on the concatenate of all sequences showed the monophyly of the genus Tetratrichomonas with respect to the genus Trichomonas.

There is little doubt that genes can spread across unrelated prokaryotes, eukaryotes and even between these domains. It is expected that organisms inhabiting a common niche may exchange their genes even more often due to their physical proximity and similar demands. One such niche is anaerobic or microaerophilic environments in some sediments and intestines of animals. Indeed, enzymes advantageous for metabolism in these environments often exhibit an evolutionary history incoherent with the history of their hosts indicating potential transfers. The evolutionary paths of some very basic enzymes for energy metabolism of anaerobic eukaryotes (pyruvate formate lyase, pyruvate:ferredoxin oxidoreductase, [FeFe]hydrogenase and arginine deiminase) seems to be particularly intriguing and although their histories are not identical they share several unexpected features in common. Every enzyme mentioned above is present in groups of eukaryotes that are unrelated to each other. Although the enz...

We report the light-microscopic morphology and ultrastructure of a novel free-living, heterotrophic protist, Creneis carolina gen. et sp. nov. isolated from marine anoxic sediments. C. carolina is a heterotrophic, obligately anaerobic amoeboid flagellate, and superficially resembles Mastigamoeba (Amoebozoa: Archamoebae) or Breviata (Breviatea) by possessing a single anterior flagellum closely associated with the nucleus, and because it appears to be an anaerobe. However, its life cycle contains multiflagellate cells with an unusual morphology. The structure of the mastigont of C. carolina is unique and not readily comparable with any eukaryotic group. Unexpectedly, phylogenetic analyses of SSU rDNA and of a concatenate of α- and β-tubulin genes with SSU rDNA convincingly showed that C. carolina is a member of Heterolobosea and belongs to the taxon Tetramitia.

We studied morphological and molecular polymorphism of 53 Tetratrichomonas isolates obtained from amphibian, reptilian, mamma- lian hosts, and from a slug with the aid of protargol staining and analyses of ITS1-5.8S rRNA-ITS2, SSU rRNA, and -tubulin gene sequences. The phylogenetic tree based on the concatenate of all sequences showed the monophyly of the genus Tetratrichomonas with respect to the genus

ABSTRACT In the vast and diversified eukaryotic group Stramenopila we can find many different life strategies, one of them being parasitism. There are two groups of stramenopiles containing important parasites of vertebrates: the oomycetes (e.g. Saprolegnia) and the wholly parasitic group Slopalinida+its sister taxon—Blastocystis. The order Slopalinida comprises families Opalinidae and Proteromonadidae. The two families are considered related based on the structure of basal bodies and their appendages and the presence of subpelicular microtubules. However, a robust recognition of phylogenetic affinities of Opalinidae—the peculiar multinucleated intestine commensals of frogs—has been hindered by the absence of reliable molecular data. Up to now, all attempts to sequence opalinid genes failed, as the obtained sequences labeled as Protoopalina intestinalis, Cepedea virguloidea and Opalina ranarum in GenBank apparently originate from a zygomycete contamination. We present the first molecular data for the family Opalinidae—SSU rRNA gene of Protoopalina intestinalis. Our phylogenetic analyses undoubtedly show opalinids as a sister group to Proteromonas within the Stramenopila clade, confirming the monophyly of Patterson's order Slopalinida. The enigmatic genus Blastocystis is resolved with high statistical support as a sister group to Slopalinida. Our analyses clearly demonstrate that Cavalier–Smith's phylum Bigyra, which comprises Oomycetes and their relatives together with Slopalinida and Blastocystis, is not monophyletic. We also show, that Blastocystis sp. isolate obtained from the red-footed tortoise (Geochelone carbonaria), forms a sister group to all Blastocystis isolates from birds and mammals sequenced so far.

We present the first molecular phylogenetic examination of the evolutionary position of retortamonads, a group of mitochondrion-lacking flagellates usually found as commensals of the intestinal tracts of vertebrates. Our phylog- enies include small subunit ribosomal gene sequences from six retortamonad isolates—four from mammals and two from amphibians. All six sequences were highly similar (95%-99%), with those from mammals being almost

S-adenosylmethionine is one of the most important metabolites in living cells and is synthesized in a single reaction catalyzed by methionine adenosyltransferase (MAT). At the sequence and structural level, this enzyme is one of the most conserved proteins known. Here we show that some representatives of three distantly related eukaryotic lineages--dinoflagellates, haptophytes, and euglenids--possess a highly divergent type of MAT, which we call MATX. Even though MATX contains all the sites known to be involved in catalysis and the association of monomers, it also has four insertions throughout the protein that are not observed in other MAT homologs. The phylogenetic distribution and affinities of MATX suggest that it originated in a single eukaryotic lineage and was spread via multiple events of eukaryote-to-eukaryote lateral gene transfer. We suggest a tentative model in which the origin of MATX is connected with the progression of secondary endosymbiosis.