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Fernando Gómez, Lu Wang, Senjie Lin
Consortia of the peritrich ciliate Vorticella oceanica and the planktonic diatom Chaetoceros coarctactus are reported from the South Atlantic Ocean. The morphologies of the constituent species were similar to their counterparts from other geographical regions, revealing a widespread distribution in tropical waters. Besides, we describe Pseudovorticella coscinodisci sp. nov. that lives on Coscinodiscus wailesii and other pelagic diatoms off Brazil. The zooids were 34-45μm long, and 19-30μm wide with a stalk too short to coil...
March 20, 2018: Protist
Garvin Schulz, Mark Maraun, Eckhard Völcker, Stefan Scheu, Valentyna Krashevska
Morphological features are often the only characteristics suitable for identification of taxa in testate amoebae, especially in ecological and palaeoecological studies. However, whereas the morphology of some species is rather stable it may vary considerably in others. Within the order Arcellinida the genus Trigonopyxis with the type species Trigonopyxis arcula is morphologically highly variable. To identify reliable characteristics for morphology-based taxon delineation we investigated variations in shell size, pseudostome diameter and pseudostome form in T...
March 13, 2018: Protist
Larry Simpson
No abstract text is available yet for this article.
March 6, 2018: Protist
Gert Hansen, Niels Daugbjerg, Øjvind Moestrup
The rarely recorded dinoflagellate Hemidinium ochraceum Levander was isolated from a rainwater rock-pool in Finland and the motile stage studied by light- and electron microscopy and molecular sequencing. The ultrastructure of the motile stage revealed several features not previously observed in other dinoflagellates, e.g. thecal plates with inwards 'knobs' and a peculiar corrugated left sulcal plate. The apparent lack of the R2 and R4 flagellar roots was also unusual. The typical plate tabulation was 4', 2a, 8″, cx , 4c,?s, 3‴, cy , 1p, 2″″, cx and cy being extra plates associated with the cingulum, but intraspecific variations were observed in shape and number of plates...
February 24, 2018: Protist
Juliane Kretschmann, Paweł M Owsianny, Anže Žerdoner Čalasan, Marc Gottschling
Because of a great variety of remote localities and cold habitats, the Tatra Mountains are home to many freshwater protist lineages. Dinophytes have been subjected to a number of studies from this area dating mostly to the first half of the 20th century, but their true diversity remains elusive until today. We collected water tow samples at five lakes in the Tatra Mountains in order to establish monoclonal strains. We found four lineages that were distinctive in terms of morphology and DNA sequence data and that could be assigned to peridinialean Parvodinium...
February 23, 2018: Protist
Daria Tashyreva, Galina Prokopchuk, Akinori Yabuki, Binnypreet Kaur, Drahomíra Faktorová, Jan Votýpka, Chiho Kusaka, Katsunori Fujikura, Takashi Shiratori, Ken-Ichiro Ishida, Aleš Horák, Julius Lukeš
Diplonemids were recently found to be the most species-rich group of marine planktonic protists. Based on phylogenetic analysis of 18S rRNA gene sequences and morphological observations, we report the description of new members of the genus Rhynchopus - R. humris sp. n. and R. serpens sp. n., and the establishment of two new genera - Lacrimia gen. n. and Sulcionema gen. n., represented by L. lanifica sp. n. and S. specki sp. n., respectively. In addition, we describe the organism formerly designated as Diplonema sp...
February 21, 2018: Protist
Denis H Lynn, Martin Kolisko, William Bourland
The class Nassophorea includes the microthoracids and nassulids, which share morphological similarities in their somatic kinetids and cytopharyngeal baskets. The monophyly of this clade has been challenged by small subunit rRNA gene sequences and multi-gene analyses that do not provide strong support. To provide a more robust test of the monophyly of the Nassophorea, phylogenomic analyses were based on 124 genes derived from the single-cell transcriptomes of the microthoracid Pseudomicrothorax dubius and the nassulid Furgasonia blochmanni...
February 13, 2018: Protist
Andrey I Azovsky, Yuri A Mazei
For the first time, free-living ciliates were studied in sediments from a variety of habitats in the Kara Sea (the Arctic Ocean). Ciliates were found in a wide range of environmental conditions (from the intertidal zone up to depths of 554m, from salinities ranging from 0 to 34psu, and from coarse sands and gravel to muddy sediments), with total abundances varying from 1 to 127ind/cm3 . Altogether, 114 species were identified, most of which were widely distributed and were previously reported from other Arctic regions...
February 12, 2018: Protist
Léa Cysne-Finkelstein, Mariana Silva-Almeida, Bernardo Acácio Santini Pereira, Karen Dos Santos Charret, Álvaro Luiz Bertho, Leonardo Soares Bastos, Luzia de Oliveira Pinto, Francisco Odêncio Rodrigues de Oliveira, Mirian Cláudia da Souza Pereira, Carlos Roberto Alves
The present study demonstrates that the Leishmania (Viannia) braziliensis strain MCAN/BR/1998/R619 is composed of multiple subpopulations with measurable distinctions. Single parasites were separated from a culture of promastigotes in stationary phase by cell sorting and then cultivated as subpopulations. Subsequently, these subpopulations were evaluated for features of in vitro growth, infectivity to murine macrophages and proteinase gene expression. The first evidence of distinct characteristics was observed during the in vitro cultivation of isolated subpopulations, as distinct clusters of patterns were formed among the cultures, indicating the existence of quantifiable fluctuations in metrics...
February 2018: Protist
Sergey A Karpov, Purificación López-García, Maria A Mamkaeva, Vladimir I Klimov, Andrey E Vishnyakov, Victoria S Tcvetkova, David Moreira
Fungi encompass, in addition to classically well-studied lineages, an ever-expanding diversity of poorly known lineages including zoosporic chytrid-like parasites. Here, we formally describe Amoeboradix gromovi gen. et sp. nov. comprising a set of closely related strains of chytrid-like parasites of the yellow-green alga Tribonema gayanum unusually endowed with amoeboid zoospores. Morphological and ultrastructural features of A. gromovi observed by light and transmission electron microscopy recall previous descriptions of Rhizophydium anatropum...
February 2018: Protist
Kwi Young Han, Louis Graf, Carolina P Reyes, Barbara Melkonian, Robert A Andersen, Hwan Su Yoon, Michael Melkonian
Systematists increasingly use molecular markers to identify species; however, most microalgae were described before gene sequencing and type specimens were often ink drawings. Cryptic speciation and biogeographic isolation are other potential problems when anchoring an old species name with a modern gene sequence. Therefore when biological type material is absent, the best approach is to recollect the alga from the type locality and sequence genes. Sarcinochrysis marina, described in 1930 by Geitler from the Canary Islands, Spain, is the oldest Pelagophyceae genus...
February 2018: Protist
Sandra L Baldauf, Maria Romeralo, Omar Fiz-Palacios, Nahid Heidari
Dictyostelia is a monophyletic group of transiently multicellular (sorocarpic) amoebae, whose study is currently limited to laboratory culture. This tends to favour faster growing species with robust sorocarps, while species with smaller more delicate sorocarps constitute most of the group's taxonomic breadth. The number of known species is also small (∼150) given Dictyostelia's molecular depth and apparent antiquity (>600 myr). Nonetheless, dictyostelid sequences are rarely recovered in culture independent sampling (ciPCR) surveys...
February 2018: Protist
Vittorio Boscaro, Sergei I Fokin, Giulio Petroni, Franco Verni, Patrick J Keeling, Claudia Vannini
Symbiosis is a diverse and complex phenomenon requiring diverse model systems. The obligate relationship between a monophyletic group of Euplotes species ("clade B") and the betaproteobacteria Polynucleobacter and "Candidatus Protistobacter" is among the best-studied in ciliates, and provides a framework to investigate symbiont replacements. Several other Euplotes-bacteria relationships exist but are less understood, such as the co-dependent symbiosis between Euplotes magnicirratus (which belongs to "clade A") and the alphaproteobacterium "Candidatus Devosia euplotis"...
February 2018: Protist
Jan Vazač, Zoltán Füssy, Irena Hladová, Sireesha Killi, Miroslav Oborník
Chromera velia is an alveolate alga which represents the closest known phototrophic relative to apicomplexan parasites. Although the nuclear, mitochondrial, and plastid genomes of this alga have been sequenced, the number of chromosomes and ploidy of C. velia are unknown. We explored ploidy in the vegetative cell, the predominant stage in cultures of Chromera, using the tyramide signal amplification-fluorescence in situ hybridization (TSA-FISH) in isolated nuclei of C. velia. Probes were derived from three single copy genes coding for 4-diphosphocytidyl-2-C-methyl-D-erythritol (CDP-ME) kinase, 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MEcPP) synthase and Topoisomerase II...
February 2018: Protist
Kenneth Dumack, Ferry Siemensma, Michael Bonkowski
The genus Penardeugenia DEFLANDRE 1958 accommodates a single species which was described as Pamphagus bathybioticus PENARD 1904. Although this species seems to be well characterized in its description, it has never been recorded again. Despite its possession of silica scales, it was assigned to the scale-lacking Chlamydophryidae (Thecofilosea, Cercozoa). We here present morphological data of three isolates. One of them was successfully cultured and enabled the amplification of its SSU rDNA sequence. Molecular analyses revealed the evolutionary origin of Penardeugenia in the scale-bearing flagellate class Thaumatomonadida, which is backed up by morphological similarities of their scales...
February 2018: Protist
Sanea Sheikh, Mats Thulin, James C Cavender, Ricardo Escalante, Shin-Ichi Kawakami, Carlos Lado, John C Landolt, Vidyanand Nanjundiah, David C Queller, Joan E Strassmann, Frederick W Spiegel, Steven L Stephenson, Eduardo M Vadell, Sandra L Baldauf
Traditional morphology-based taxonomy of dictyostelids is rejected by molecular phylogeny. A new classification is presented based on monophyletic entities with consistent and strong molecular phylogenetic support and that are, as far as possible, morphologically recognizable. All newly named clades are diagnosed with small subunit ribosomal RNA (18S rRNA) sequence signatures plus morphological synapomorphies where possible. The two major molecular clades are given the rank of order, as Acytosteliales ord. nov...
February 2018: Protist
Cecília Seixas, João Gonçalves, Luís Viseu Melo, Helena Soares
Cilia are complex and dynamic organelles that have motility and sensory functions. Defects in cilia biogenesis and function are at the origin of human ciliopathies. In motile cilia, a basal body organizes the axoneme composed of nine microtubule doublets surrounding a central pair of singlet microtubules. The distal ends of axonemal microtubules are attached to the membrane by microtubule-capping structures. Little is known about the early steps of cilium assembly. Although cilia grow and resorb from their distal tips, it remains poorly understood where and when the components of the caps are first assembled...
December 2017: Protist
Mayumi Sugiura, Hajime J Yuasa, Terue Harumoto
Mating pheromones (gamone 1 and gamone 2) in the ciliate Blepharisma are biologically active substances that trigger sexual reproduction (conjugation) under starvation conditions. Gamone 1 is a glycoprotein secreted by type I cells, and gamone 2 is a tryptophan (Trp)-derivative compound secreted by type II cells. Both gamones stimulate complementary mating type cells to promote each gamone production and induce pair formation. To elucidate the biosynthetic pathway of gamone 2, we investigated the enzymes involved in the pathway and the specificity of the enzymes...
December 2017: Protist
Rounik Mazumdar, Lukas Endler, Andreas Monoyios, Michael Hess, Ivana Bilic
The protozoan flagellate Histomonas meleagridis is the causative agent of histomonosis in poultry. In turkeys, high mortality might be noticed whereas in chickens the disease is less severe despite production losses. Discovered over a century ago, molecular data on this parasite are scarce and genetic studies are in its infancy. To expand genomic information, a de novo transcriptome sequencing of H. meleagridis was performed from a virulent and an attenuated strain, cultivated in vitro as monoxenic mono-eukaryotic culture...
December 2017: Protist
Eva Bínová, David Bína, David A Ashford, Jane Thomas-Oates, Eva Nohýnková
The non-reducing disaccharide trehalose can serve as a protectant against a range of environmental stressors, such as heat, cold, or dehydration, in both prokaryotes and eukaryotes, with the exception of vertebrates. Here, we analyzed trehalose metabolism in the facultatively parasitic organism Acanthamoeba castellanii, known to respond to unfavorable external conditions by forming two resistant stages: a cyst, produced in the case of chronic stress, and a pseudocyst, formed in reaction to acute stress. The possible role of trehalose in the resistant stages was investigated using a combination of bioinformatic, molecular biological and biochemical approaches...
December 2017: Protist
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