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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...
January 11, 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...
January 9, 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"...
December 20, 2017: 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...
December 19, 2017: 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...
December 18, 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
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...
November 24, 2017: 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...
October 20, 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...
September 18, 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...
September 14, 2017: Protist
Nathalie Simon, Elodie Foulon, Daphné Grulois, Christophe Six, Yves Desdevises, Marie Latimier, Florence Le Gall, Margot Tragin, Aude Houdan, Evelyne Derelle, Fabien Jouenne, Dominique Marie, Sophie Le Panse, Daniel Vaulot, Birger Marin
The green picoalgal genus Micromonas is broadly distributed in estuaries, coastal marine habitats and open oceans, from the equator to the poles. Phylogenetic, ecological and genomic analyses of culture strains and natural populations have suggested that this cosmopolitan genus is composed of several cryptic species corresponding to genetic lineages. We performed a detailed analysis of variations in morphology, pigment content, and sequences of the nuclear-encoded small-subunit rRNA gene and the second internal transcribed spacer (ITS2) from strains isolated worldwide...
September 14, 2017: Protist
Perla Tedesco, Camino Gestal, Kristina Begić, Ivona Mladineo, Sheila Castellanos-Martínez, Gaetano Catanese, Antonio Terlizzi, Graziano Fiorito
Coccidian parasites of the genus Aggregata are known to parasitize cephalopods as definitive hosts, however one of the genus members, A. octopiana, has shown an unresolved phylogeny within the same definitive host, the common octopus (Octopus vulgaris). Our study represents a large-scale investigation aimed at characterizing morphological traits and phylogeny of A. octopiana isolated from O. vulgaris inhabiting three distinct geographic areas of the central Mediterranean: The Adriatic, Ionian and Tyrrhenian Seas...
September 11, 2017: Protist
Pernille Vængebjerg Boutrup, Øjvind Moestrup, Urban Tillmann, Niels Daugbjerg
A gymnodinioid photosynthetic dinoflagellate was isolated from Argentina and examined by light and electron microscopy and analysis of nuclear-encoded LSU rDNA. Kirithra asteri gen. et sp. nov. was proposed as morphology and molecular phylogeny separated this dinoflagellate from others within the family Ceratoperidiniaceae. Cells were surrounded by a hyaline amphiesma comprising polygonal vesicles. Each vesicle contained a honeycomb and a trilaminar structure. An anterior sulcal extension ending in a complete circle formed the apical structure complex (ASC), which characterizes Ceratoperidiniaceae...
September 9, 2017: Protist
Thomas P Roland, Matthew J Amesbury, David M Wilkinson, Dan J Charman, Peter Convey, Dominic A Hodgson, Jessica Royles, Steffen Clauß, Eckhard Völcker
Precise and sufficiently detailed morphological taxonomy is vital in biology, for example in the accurate interpretation of ecological and palaeoecological datasets, especially in polar regions, where biodiversity is poor. Testate amoebae on the Antarctic Peninsula (AP) are well-documented and variations in their population size have recently been interpreted as a proxy for microbial productivity changes in response to recent regional climate change. AP testate amoeba assemblages are dominated by a small number of globally ubiquitous taxa...
August 3, 2017: Protist
Petr Táborský, Tomáš Pánek, Ivan Čepička
We report discovery of a new lineage of anaerobic marine amoebae and amoeboflagellates, Anaeramoeba gen. nov., represented by six newly described species. The trophic form of Anaeramoeba spp. is an amoeba corresponding to the uncommon flabellate or flamellian morphotype - it is fan-shaped and produces an anterior, flattened hyaline zone and posterior hyaline projections. In contrast to other representatives of these morphotypes, cells of Anaeramoeba spp. possess acristate mitochondrion-related organelles associated with prokaryotic symbionts, and a large acentriolar centrosome...
August 2, 2017: Protist
Pedro Murúa, Franz Goecke, Renato Westermeier, Pieter van West, Frithjof C Küpper, Sigrid Neuhauser
Phytomyxea are obligate endoparasites of angiosperm plants and Stramenopiles characterised by a complex life cycle. Here Maullinia braseltonii sp. nov., an obligate parasite infecting the bull kelp Durvillaea (Phaeophyceae, Fucales) from the South-Eastern Pacific (Central Chile and Chiloe Island) and South-Western Atlantic (Falkland Islands, UK) is described. M. braseltonii causes distinct hypertrophies (galls) on the host thalli making it easily identifiable in the field. Sequence comparisons based on the partial 18S and the partial 18S-5...
August 2017: Protist
Brajogopal Samanta, Michael E Kinney, Quentin Heffell, James M Ehrman, Irena Kaczmarska
We examined gametogenesis and auxospore development in the cymatosiroid diatom Brockmanniella brockmannii. Our mating experiments demonstrated that the clones were homothallic, self-compatible, produced two eggs per oogonium and four hologenous uniflagellate male gametes per spermatogonium. Auxospores grew free in the culture medium and the most external layer of the auxospore wall was made up of spinescent scaly elements in their early globular stage of development. The anisodiametric expansion of the globular auxospore was rather limited, at best proceeding only to a sub-globular stage...
July 20, 2017: Protist
Nicholas A T Irwin, Mona Sabetrasekh, Denis H Lynn
Ciliates within the order Mobilida comprise a group of ectosymbionts that form ecologically and economically important symbioses with aquatic organisms. However, despite their significance, the factors driving mobilid diversification are poorly understood. To address this, we sought to examine the genetic diversity of two mobilid families, the trichodinids and urceolariids, over geographical areas and from different hosts. To this end we collected and provide morphological and molecular characterizations of three species of Trichodina: Trichodina domerguei and Trichodina tenuidens from three-spined sticklebacks, and Trichodina unionis from snails...
July 14, 2017: Protist
Jane Harmer, Xin Qi, Gabriella Toniolo, Aysha Patel, Hannah Shaw, Fiona E Benson, Michael L Ginger, Paul G McKean
TOF-LisH-PLL motifs define FOP family proteins; some members are involved in flagellum assembly. The critical role of FOP family protein FOR20 is poorly understood. Here, we report relative localisations of the four FOP family proteins in parasitic Trypanosoma brucei: TbRP2, TbOFD1 and TbFOP/FOP1-like are mature basal body proteins whereas TbFOR20 is present on pro- and mature basal bodies - on the latter it localises distal to TbRP2. We discuss how the data, together with published work for another protist Giardia intestinalis, informs on likely FOR20 function...
July 13, 2017: Protist
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