Molecular phylogenies based on the small subunit ribosomal RNA gene (SSU or 18S ribosomal DNA (rDNA)) revealed recently the existence of a relatively large and widespread group of eukaryotes, ...branching at the base of the fungal tree. This group, comprising almost exclusively environmental clones, includes the endoparasitic chytrid Rozella as the unique known representative. Rozella emerged as the first fungal lineage in molecular phylogenies and as the sister group of the Microsporidia. Here we report rDNA molecular phylogenetic analyses of two endonuclear parasites of free-living naked amoebae having microsporidia-like ultrastructural features but belonging to the rozellids. Similar to microsporidia, these endoparasites form unflagellated walled spores and grow inside the host cells as unwalled nonphagotrophic meronts. Our endonuclear parasites are microsporidia-like rozellids, for which we propose the name Paramicrosporidium, appearing to be the until now lacking morphological missing link between Fungi and Microsporidia. These features contrast with the recent description of the rozellids as an intermediate wall-less lineage of organisms between protists and true Fungi. We thus reconsider the rozellid clade as the most basal fungal lineage, naming it Rozellomycota.
The problem of uncertainty as a general consequence of incomplete information and the approach to quantify uncertainty in metrology is addressed. Then, the statistical foundation of the concepts of ...uncertainty in measurements is discussed. The basics of the ISO Guide to the Expression of Uncertainty in Measurement as well as of characteristic limits according to ISO 11929 are described and, finally, the role of measurement uncertainties in the assessment of conformity to requirements is dealt with in detail.
Intracellular parasitism often results in gene loss, genome reduction, and dependence upon the host for cellular functioning. Rozellomycota is a clade comprising many such parasites and is related to ...the diverse, highly reduced, animal parasites, Microsporidia. We sequenced the nuclear and mitochondrial genomes of
Rozellomycota, an intranuclear parasite of amoebae. A canonical fungal mitochondrial genome was recovered from
that encodes genes necessary for the complete oxidative phosphorylation pathway including Complex I, differentiating it from most endoparasites including its sequenced relatives in Rozellomycota and Microsporidia. Comparative analysis revealed that
shares more gene content with distantly related Fungi than with its closest relatives, suggesting that genome evolution in Rozellomycota and Microsporidia has been affected by repeated and independent gene losses, possibly as a result of variation in parasitic strategies (e.g. host and subcellular localization) or due to multiple transitions to parasitism.
Amoebophagous fungi are represented in all fungal groups: Basidiomycota, Ascomycota, Zygomycota, and Chytridiomycota. The amoebophagous fungi, within the zygomycota (Zoopagales, Zoopagomycota), ...mainly affect naked amoebae as ectoparasites or endoparasites. It is rather difficult to isolate members of the Zoopagales, because of their parasitic lifestyle, and to bring them into culture. Consequently, gene sequences of this group are undersampled, and its species composition and phylogeny are relatively unknown. In the present study, we were able to isolate amoebophagous fungi together with their amoeba hosts from various habitats (moss, pond, bark, and soil). Altogether, four fungal strains belonging to the genera
Acaulopage
and
Stylopage
plus one unidentified isolate were detected. Sequences of the 18S rDNA and the complete ITS region and partial 28S (LSU) rDNA were generated. Subsequent phylogenetic analyses showed that all new isolates diverge at one branch together with two environmental clonal sequences within the Zoopagomycota. Here, we provide the first molecular characterization of the genus
Stylopage
.
Stylopage
is closely related to the genus
Acaulopage
. In addition, taxonomy and phylogeny of amoebophagous fungi and their ecological importance are reviewed based on new sequence data, which includes environmental clonal sequences.
Microsporidia are widespread endoparasites of animals, including humans. They are characterized by highly modified morphological and genetic features that cause difficulties in elucidating their ...enigmatic origin and evolution. Recent advances, however, indicate that the Microsporidia have emerged from the Rozellomycota, forming together either the most basal lineage of the Fungi or its closer relative. The Rozellomycota comprise a huge diversity of uncultured environmental clones, with a very few known species endoparasitic of algae and water moulds, like the chytrid-like
Rozella
, and of free-living amoebae, like
Nucleophaga
and the microsporidia-like
Paramicrosporidium
. A possible ancestral microsporidium,
Mitosporidium
, has recently been described from the water flea
Daphnia
, since the phylogenomic reconstruction showed that it branches to the root of the microsporidian tree, while the genome analysis revealed a fungal-like nuclear genome and the persistence of a mitochondrial genome. Here we report the 18S rDNA molecular phylogeny of an additional microsporidium-like endoparasite of amoebae, which has a developmental cycle almost identical to that of
Nucleophaga amoebae
. Our results show that the endoparasite is closely related to
N. amoebae
, forming a distinct species, for which we propose the name
Nucleophaga terricolae
. Furthermore, the
Nucleophaga
lineage is recovered as sister to the Microsporidia while
Mitosporidium
turns out to be member of a well-supported group of environmental clones. These results raise the question about the actual ancestry of the Microsporidia within the Rozellomycota. A precise and robust phylogeny will require further comparative genomic studies of these various strains, and should also consider the primitive microsporidia, for which genetic data are still lacking, because all these organisms are essentially morphologically similar.
Recent studies showed that the huge diversity branching at or near the phylogenetic root of the fungal kingdom, mostly constituted by uncultured environmental clones, is actually characterized by ...intracellular predators/parasites of various eukaryotes. These form three related lineages: the Aphelidea, endoparasites of algae; the Rozellomycota, with Rozella species mainly endoparasites of water moulds, and Paramicrosporidium species endonuclear parasites of amoebae; and the Microsporidia, mainly endoparasites of animals. Increasing evidence suggests the emergence of Microsporidia from within Rozellomycota; however, their fungal or protistan nature is still unclear. Here, we report the molecular phylogeny based on the small subunit ribosomal RNA (SSU rDNA) gene, of an additional endoparasite of amoebae, corresponding to the old enigmatic chytrid Nucleophaga amoebae described in the nineteenth century. Our results show that Nucleophaga, possessing a morphotype intermediate between Rozella and Paramicrosporidium, emerges as a unique lineage within the Rozellomycota. The recovery and characterization of new members of Rozellomycota are of high value for the understanding of the early evolutionary history of the Fungi and related lineages.
The problem of uncertainty as a general consequence of incomplete information and the approach to quantify uncertainty in metrology is addressed. Then, this paper discusses some of the controversial ...aspects of the statistical foundation of the concepts of uncertainty in measurements. The basics of the ISO Guide to the Expression of Uncertainty in Measurement as well as of characteristic limits according to ISO 11929 are described and the needs for a revision of the latter standard are explained.
•Bayesian statistics provides the sole basis of recent developments in metrology.•The original GUM now turns out to be a special case of a general methodology to quantify uncertainty.•As a consequence the GUM is being revised in order to align it with its supplements.•The GUM provided a basis for calculating characteristic values of measurements.•In the course of a routine revision, ISO 11929 will be made consistent with the revised GUM.
Using ameba coculture, we grew a Naegleria endosymbiont. Phenotypic, genetic, and phylogenetic analyses supported its affiliation as Protochlamydia naegleriophila sp. nov. We then developed a ...specific diagnostic PCR for Protochlamydia spp. When applied to bronchoalveolar lavages, results of this PCR were positive for 1 patient with pneumonia. Further studies are needed to assess the role of Protochlamydia spp. in pneumonia.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The genus Sappinia belongs to the family Thecamoebidae within the Discosea (Amoebozoa). For long time the genus comprised only two species, S. pedata and S. diploidea, based on morphological ...investigations. However, recent molecular studies on gene sequences of the small subunit ribosomal RNA (SSU rRNA) gene revealed a high genetic diversity within the genus Sappinia. This indicated a larger species richness than previously assumed and the establishment of new species was predicted. Here, Sappinia platani sp. nov. (strain PL247) is described and ultrastructurally investigated. This strain was isolated from the bark of a sycamore tree (Koblenz, Germany) like the re-described neotype of S. diploidea. The new species shows the typical characteristics of the genus such as flattened and binucleate trophozoites with a differentiation of anterior hyaloplasm and without discrete pseudopodia as well as bicellular cysts. Additionally, the new species possesses numerous endocytobionts and dictyosomes. The latter could not be found in previous EM studies of the genus Sappinia. Standing forms, a character of the species S. pedata, could be formed on older cultures of the new species but appeared extremely seldom. A loose layer of irregular, bent hair-like structures cover the plasma membrane dissimilar to the glycocalyx types as formerly detected in other Sappinia strains.
Atom ratios of the isotopes
239Pu,
240Pu,
241Pu and
244Pu were determined in sediments and soils from Bikini atoll using low energy Accelerator Mass Spectrometry. All samples had been contaminated by ...local fallout from nuclear weapon testing between 1946 and 1958 and show significant variations in the isotopic composition, which are ascribed to the different yields of single tests and to the mixture of material from various devices. Differences in the
244Pu/
239Pu ratio (2.8–5.7×10
−4) are more pronounced than in the
240Pu/
239Pu ratio of the same samples and provide complementary information to distinguish the sources of contamination.
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