3,088 research outputs found
Molecular characterization of the obligate endosymbiont "Caedibacter macronucleorum" Fokin and Gortz, 1993 and of its host Paramecium duboscqui strain Ku4-8
No full textAbstract: Bacterial endosymbionts of protozoa were often described as new species by protozoologists mainly on the basis of few morphological characters and partly by host specificity. Many of these species have never been validated by prokaryotic microbiologists whose taxonomic rules are quite different from those of protozoologists, who use the Zoological Code of Nomenclature. "Caedibacter macronucleorum" Fokin and Gortz 1993, an endosymbiont of Paramecium duboscqui, belongs to this category. Here we provide the molecular characterization of this organism and of its host P. duboscqui strain Ku4-8. Bacterial 16S rRNA gene sequence analysis proved that "C. macronucleorum" belongs to the Alphaproteobacteria. It is closely related to Caedibacter caryophilus but not to Caedibacter taeniospiralis, which belongs to the Gammaproteobacteria. "Caedibacter macronucleorum" and C. caryophilus 16S rRNA genes show a similarity value of 99%. This high 16S rRNA sequence similarity and the lack of ..
On the importance of attentive reading of research articles: The case study of Frontonia (Peniculia, Oligohymenophora, Ciliophora) species descriptions and redescriptions
No full textA commonly encountered problem of ignoring or inattentive reading of scientific articles by some protistologists of the past and present has been revealed using the case study of taxonomy of the ciliate genus Frontonia. The comparison between materials from literature and own investigations allowed the author to conclude that F. vernalis Ehrenberg, 1833 cannot to be a valid species and assume that it is rather a cluster of closely related freshwater ciliates with one contractile vacuole and a stable ability to accommodate green algae as the cytoplasmic symbionts. "F. vernalis", as described by Bullington (1939), was shown to have little in common with the original description by Ehrenberg and most likely is a brackishwater ciliate similar to F. fusca. F. oculiaris described by the same author (Bullington, 1939) is obviously F. fusca, and the name "F. oculiaris" should be considered as a younger synonym of the latter. Thus, redescription of F. oculiaris (Pan et al., 2013b) should be treated just as a morphological study of the local Chinese population of F. fusca. The redescription of F. canadensis from brackish waters by the same authors can be considered as a description of a new species that has little in common with the original description of this freshwater ciliate (Roque and Puytorac, 1972). Recent phylogenetical reconstructions indicate the necessity to split Frontonia into several genera
Bütschli, O
No full textOtto Bütschli (1848–1920) – professor of zoology
and palaeontology at Heidelberg University, made
fundamental contributions to cytology and the
investigation of unicellular organisms, first of all
ciliates. Bütschli was the first to recognise and to
demonstrate that conjugation of ciliates was not
a reproductive process but a sexual reorganisation
of the cell similar to cross-fertilisation. His
protozoan studies culminated in a three-volume
monograph (Bütschli, 1880–1882, 1883–1887,
1887–1889), which also contained many of his
own original works. This 2000-page critical review
of contemporary knowledge actually established
protozoology as an autonomous discipline. Moreover,
in 1875, Bütschli was the first to identify and
determine the sequence of the stages of nuclear
division (mitosis) in several types of animal cells.
He provided excellent descriptions of dividing
cells
Protistologist Wladimir Timopheyevich Schewiakoff (1859-1930). On the shores of the Gulf of Naples
No full textThis article narrates the history of Acantharia research in the Gulf of Naples (Mediterranean Sea) by the well-known Russian scientist, Professor W.T. Schewiakoff, as well as his efforts to study Foraminifera and Ciliophora in the same water basin. All those activities are presented against a background of the protistologist's own life story
Effect of local UV irradiation of the generative nucleus on the vegetative functions of the infusorian, Paramecium putrinum
No full textThe influence of the generative nucleus on the vitality in three clones of Paramecium putrinum was studied. The selective functional inactivation of the micronucleus (MI) was achieved with a local ultraviolet microbeam. After irradiation of micronuclei these soon disappeared and the irradiated cells perished shortly afterwards. In the part of UV treated-subclones the macronucleus (MA) fragmentation was discovered. It is possible that the fragments of MA are some kind of functional replacement of the lost or damaged generative nucleus. That data obviously demonstrate the function of MI of P. putrinum during its vegetative growth
Bacterial symbiosis in ciliates (Alveolata, Ciliophora): Roads traveled and those still to be taken
No full textThe diversity of prokaryotic symbionts in Ciliophora and other protists is fascinatingly rich; they may even include some potentially pathogenic bacteria. In this review, we summarize currently available data on biodiversity and some morphological and biological peculiarities of prokaryotic symbionts mainly within the genera Paramecium and Euplotes. Another direction of ciliate symbiology, neglected for a long time and now re-discovered, is the study of epibionts of ciliates. This promises a variety of interesting outcomes. Last, but not least, we stress the new technologies, such as next generation sequencing and the use of genomics data, which all can clarify many new aspects of relevance. For this reason, a brief overview of achievements in genomic studies on ciliate's symbionts is provided. Summing up the results of numerous scientific contributions, we systematically update current knowledge and outline the prospects as to how symbiology of Ciliophora may develop in the near future
Paramecium (ciliophora, protista). Taxonomy and phylogenetic relationships
No full textThe relationships between thirteen Paramecium species were investigated using a number of biological, morphometric, and molecular-biological (SS rRNA gene sequences) characters. Analysis of sequences was also applied for Frontonia, Lembadion, and Urocentrum species. The similar results were obtained by using various methods. The genus Paramecium is found to be monophyletic and along with other peniculines (Lembadion and Frontonia) it composes Peniculia subclass of the class Oligohymenophorea. The data obtained support no variant of the Paramecium classification (2 subgroups according to Woodruff and 3 subgroups in Jankowsky's taxonomy) suggested earlier. Paramecium bursaria, P. duboscqui, and P. putrinum are the most ancient and divergent species within the genus. Part of the woodruffi subgroup (P. woodruffi, P. nephridiatum and P. calkinsi) and the aurelia subgroup (P. aurelia complex, P. jenningsi, P. caudatum, and P. multimicronucleatum) from two monophyletic clusters and can be considered as subgenera. The taxonomy of Paramecium should be reconstructed. The subclass Peniculia should be divided into two orders - Urocentrida and Peniculida
Prof. H.-D. Görtz and his contribution to our knowledge of protozoan symbiosis
No full textSince the beginning of the 1980s, the Paramecium–Holospora system has become an important model and a subject of international scientific cooperation in symbiosis studies, established by Prof. H.-D. Görtz. In the article, a brief sketch of the scientist's life, his areas of interest, expertise and his contribution to our knowledge of protozoan symbiosis are discussed
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