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Alan Warren - One of the best experts on this subject based on the ideXlab platform.
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an integrative investigation of parabistichella variabilis protista ciliophora hypotrichia including its general morphology ultrastructure ontogenesis and molecular phylogeny
Journal of Eukaryotic Microbiology, 2020Co-Authors: Jingyi Dong, Xumiao Chen, Yongqiang Liu, Xinpeng Fan, Alan WarrenAbstract:Hypotrichs are a highly differentiated and very diverse group of ciliated protists. Their systematics and taxonomy are challenging and call for detailed investigations on their general morphology, ultrastructure, ontogenesis, and molecular phylogeny. Here, a comprehensive study is conducted on a brackish water population of Parabistichella variabilis using light and electron microscopy and phylogenetic analyses based on small subunit ribosomal DNA sequence data. Its morphology, including the infraciliature, pellicle, nuclei, buccal seal, and Extrusomes, is documented. The present findings indicate that in P. variabilis: (i) the cortical granules are Extrusomes, which differ from those of other hypotrichs; (ii) the buccal seal is bounded by the plasma membrane and contains a single layer of longitudinal microtubules; (iii) two contractile vacuoles might be present rather than one; and (iv) the pharyngeal disks are bounded by a single membrane. Early-to-middle stages of ontogenesis are described for the first time, enabling the complete characterization of this process. Phylogenetic analyses indicate that Parabistichella variabilis is closely related to several species from different genera, such as Orthoamphisiella breviseries, Uroleptoides magnigranulosus, and Tachysoma pellionellum. However, ultrastructural and gene sequence data for more taxa are needed in order to resolve the systematics of Parabistichella.
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biodiversity of oligotrich ciliates in the south china sea description of three new strombidium species protozoa ciliophora oligotrichia with phylogenetic analyses
Systematics and Biodiversity, 2015Co-Authors: Wen Song, Weibo Song, Khaled A S Alrasheid, Xiaolu Zhao, Weiwei Liu, Saleh A Alfarraj, Alan WarrenAbstract:The morphology and small subunit ribosomal RNA (SSU rRNA) gene sequences of three new species of ciliates in the genus Strombidium are recorded: S. paracapitatum sp. nov., S. cuneiforme sp. nov., and S. caudispina sp. nov. Strombidium paracapitatum sp. nov. is characterized by having a prominent and transparent apical protrusion and two types of Extrusomes. Strombidium cuneiforme sp. nov. differs from its congeners in the combination of its long conical body shape, eyespot and elongated tail. Strombidium caudispina sp. nov. is recognized by its posterior spine and short ventral kinety. In SSU rRNA gene trees, all members of the genus Strombidium cluster into three separate groups. The first group is composed of nine Strombidium species including S. cuneiforme sp. nov., plus Williophrya maedai. The second group consists of S. paracapitatum sp. nov., S. caudispina sp. nov. and three congeners. The third group comprises S. conicum and S. chlorophilum.http://zoobank.org/urn:lsid:zoobank.org:pub:25871A6B-772A-...
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pseudoamphisiella alveolata kahl 1932 nov comb a large marine hypotrichous ciliate from china protozoa ciliophora hypotrichida
European Journal of Protistology, 2000Co-Authors: Weibo Song, Alan WarrenAbstract:Summary The hypotrichous ciliate Pseudoamphisiella aheolata ( Kahl, 1932 ) nov. comb, (formerly Holosticha aheolata Kahl, 1932 ), a poorly-known, marine organism with a unique alveolar covering on the cell surface, was isolated from coastal waters off Qingdao (Tsingtao), People's Republic of China. Its morphology and infraciliature were investigated and described from organisms observed in vivo and following protargol silver impregnation. Based on these observations, an improved diagnosis for this species is presented: slightly contractile, marine Pseudoamphisiella, in vivo 120–240 μm×50–80 μm with 2 macronuclei and conspicuous bar-like Extrusomes within an alveolar covering on the cell surface. On average, 50 adorai membranelies; 3 frontal and 2 buccal cirri; two well separated ventral rows, each with about 12 cirri; 12–16 transverse cirri extending about 2/5 of cell length; 14–20 and 12–14 cirri in left and right marginal rows respectively; 11–16 caudal cirri which connect the left and right marginal rows completely; 10–12 dorsal kineties. Based mainly on its ciliature, P. aheolata is compared with its only known congener, P. lacazei ( Maupas, 1883 ). The systematic position of the morphologically similar Keronopsis macrostoma Dragesco, 1963 is also briefly discussed, and is here synonymised with P. lacazei .
Michael Melkonian - One of the best experts on this subject based on the ideXlab platform.
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ultrastructure of the algivorous amoeboflagellate viridiraptor invadens glissomonadida cercozoa
Protist, 2014Co-Authors: Sebastian Hess, Michael MelkonianAbstract:The family Viridiraptoridae represents a morphologically and ecologically distinct lineage of glissomonad flagellates (Cercozoa, Rhizaria). It currently comprises two highly specialised, algivorous genera inhabiting freshwater ecosystems, Orciraptor and Viridiraptor, for which ultrastructural data were lacking. In this study, the ultrastructure of Viridiraptor invadensHess et Melkonian, the sole described species of the viridiraptorid type genus, has been studied by transmission and scanning electron microscopy. In particular the flagellar transitional region and basal apparatus, both reconstructed from serial sections, revealed ultrastructural traits, that agree with the phylogenetic placement of the viridiraptorids within Glissomonadida: The transitional region contains a distal plate/collar complex and the basal apparatus comprises two ventral posterior roots and an anterior root, all known from other glissomonads. However, two additional small microtubular roots, two conspicuous rhizoplasts and probasal bodies present during interphase represent novel characteristics. Furthermore, an acorn/V-shaped filament system was discovered at the proximal end of the flagellar transitional region and used to establish a basal body triplet numbering system for flagellate cells of the Rhizaria. Finally, ultrastructural data on perforated algal cell walls suggest that the previously described reticulocyst of Viridiraptor represents an Extrusome-derived, mesh-like coat supporting the invasion/feeding process.
Denis H Lynn - One of the best experts on this subject based on the ideXlab platform.
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Remodeling the Specificity of an Endosomal CORVET Tether Underlies Formation of Regulated Secretory Vesicles in the Ciliate Tetrahymena thermophila.
Current biology : CB, 2018Co-Authors: Daniela Sparvoli, Denis H Lynn, Elisabeth Richardson, Hiroko Osakada, Masaaki Iwamoto, Grant R Bowman, Cassandra Kontur, William A Bourland, Xun Lan, Jonathan K PritchardAbstract:Summary In the endocytic pathway of animals, two related complexes, called CORVET (class C core vacuole/endosome transport) and HOPS (homotypic fusion and protein sorting), act as both tethers and fusion factors for early and late endosomes, respectively. Mutations in CORVET or HOPS lead to trafficking defects and contribute to human disease, including immune dysfunction. HOPS and CORVET are conserved throughout eukaryotes, but remarkably, in the ciliate Tetrahymena thermophila , the HOPS-specific subunits are absent, while CORVET-specific subunits have proliferated. VPS8 (vacuolar protein sorting), a CORVET subunit, expanded to 6 paralogs in Tetrahymena . This expansion correlated with loss of HOPS within a ciliate subgroup, including the Oligohymenophorea, which contains Tetrahymena . As uncovered via forward genetics, a single VPS8 paralog in Tetrahymena ( VPS8A ) is required to synthesize prominent secretory granules called mucocysts. More specifically, Δvps8a cells fail to deliver a subset of cargo proteins to developing mucocysts, instead accumulating that cargo in vesicles also bearing the mucocyst-sorting receptor Sor4p. Surprisingly, although this transport step relies on CORVET, it does not appear to involve early endosomes. Instead, Vps8a associates with the late endosomal/lysosomal marker Rab7, indicating that target specificity switching occurred in CORVET subunits during the evolution of ciliates. Mucocysts belong to a markedly diverse and understudied class of protist secretory organelles called Extrusomes. Our results underscore that biogenesis of mucocysts depends on endolysosomal trafficking, revealing parallels with invasive organelles in apicomplexan parasites and suggesting that a wide array of secretory adaptations in protists, like in animals, depend on mechanisms related to lysosome biogenesis.
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an evolutionary switch in the specificity of an endosomal corvet tether underlies formation of regulated secretory vesicles in the ciliate tetrahymena thermophila
bioRxiv, 2017Co-Authors: Daniela Sparvoli, Denis H Lynn, Elisabeth Richardson, Hiroko Osakada, Masaaki Iwamoto, Grant R Bowman, Cassandra Kontur, William A Bourland, Jonathan K Pritchard, Tokuko HaraguchiAbstract:In the endocytic pathway of animals, two related complexes, called CORVET (Class C Core Vacuole/Endosome Transport) and HOPS (Homotypic fusion and protein sorting), act as both tethers and fusion factors for early and late endosomes, respectively. Mutations in CORVET or HOPS lead to trafficking defects and contribute to human disease including immune dysfunction. HOPS and CORVET are conserved throughout eukaryotes but remarkably, in the ciliate Tetrahymena thermophila , the HOPS-specific subunits are absent while CORVET-specific subunits have proliferated. VPS8 (Vacuolar Protein Sorting), a CORVET subunit, expanded to 6 paralogs in Tetrahymena . This expansion correlated with loss of HOPS within a ciliate subgroup including the Oligohymenophorea, which contains Tetrahymena . As uncovered via forward genetics, a single VPS8 paralog in Tetrahymena ( VPS8A ) is required to synthesize prominent secretory granules called mucocysts. More specifically, Δvps8a cells fail to deliver a subset of cargo proteins to developing mucocysts, instead accumulating that cargo in vesicles also bearing the mucocyst sorting receptor, Sor4p. Surprisingly, although this transport step relies on CORVET, it does not appear to involve early endosomes. Instead, Vps8a associates with the late endosomal/lysosomal marker Rab7, indicating target specificity switching occurred in CORVET subunits during the evolution of ciliates. Mucocysts belong to a markedly diverse and understudied class of protist secretory organelles called Extrusomes. Our results underscore that biogenesis of mucocysts depends on endolysosomal trafficking, revealing parallels with invasive organelles in apicomplexan parasites and suggesting that a wide array of secretory adaptations in protists, like in animals, depend on mechanisms related to lysosome biogenesis.
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An evolutionary switch in the specificity of an endosomal CORVET tether underlies formation of regulated secretory vesicles in the ciliate Tetrahymena thermophila
2017Co-Authors: Daniela Sparvoli, Denis H Lynn, Elisabeth Richardson, Hiroko Osakada, Masaaki Iwamoto, Grant R Bowman, Cassandra Kontur, William A Bourland, Xun Lan, Jonathan K PritchardAbstract:In the endocytic pathway of animals, two related complexes, called CORVET (Class C Core Vacuole/Endosome Transport) and HOPS (Homotypic fusion and protein sorting), act as both tethers and fusion factors for early and late endosomes, respectively. Mutations in CORVET or HOPS lead to trafficking defects and contribute to human disease including immune dysfunction. HOPS and CORVET are conserved throughout eukaryotes but remarkably, in the ciliate Tetrahymena thermophila , the HOPS-specific subunits are absent while CORVET-specific subunits have proliferated. VPS8 (Vacuolar Protein Sorting), a CORVET subunit, expanded to 6 paralogs in Tetrahymena . This expansion correlated with loss of HOPS within a ciliate subgroup including the Oligohymenophorea, which contains Tetrahymena . As uncovered via forward genetics, a single VPS8 paralog in Tetrahymena ( VPS8A ) is required to synthesize prominent secretory granules called mucocysts. More specifically, Δvps8a cells fail to deliver a subset of cargo proteins to developing mucocysts, instead accumulating that cargo in vesicles also bearing the mucocyst sorting receptor, Sor4p. Surprisingly, although this transport step relies on CORVET, it does not appear to involve early endosomes. Instead, Vps8a associates with the late endosomal/lysosomal marker Rab7, indicating target specificity switching occurred in CORVET subunits during the evolution of ciliates. Mucocysts belong to a markedly diverse and understudied class of protist secretory organelles called Extrusomes. Our results underscore that biogenesis of mucocysts depends on endolysosomal trafficking, revealing parallels with invasive organelles in apicomplexan parasites and suggesting that a wide array of secretory adaptations in protists, like in animals, depend on mechanisms related to lysosome biogenesis.
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pelagostrobilidium neptuni montagnes and taylor 1994 and strombidium biarmatum nov spec ciliophora oligotrichea phylogenetic position inferred from morphology ontogenesis and gene sequence data
European Journal of Protistology, 2005Co-Authors: Sabine Agatha, Michaela C Struderkypke, A Beran, Denis H LynnAbstract:Abstract Morphological data from life, protargol impregnation, and scanning electron microscopy were combined with genetic data not only to describe the marine plankton ciliates Pelagostrobilidium neptuni (Montagnes and Taylor, 1994) Petz, Song, and Wilbert, 1995 and Strombidium biarmatum nov. spec., but also to elucidate their phylogenetic relationships. Additionally, the ontogenesis of P. neptuni was studied and the diagnosis of the genus Pelagostrobilidium was improved due to further data from the newly affiliated species P. epacrum (Lynn and Montagnes, 1988) nov. comb. (basionym: Strobilidium epacrum Lynn and Montagnes, 1988). The phylogenetic analysis of the small subunit ribosomal RNA genes matched the morphologic and ontogenetic assigning of P. neptuni to the choreotrichid family Strobilidiidae. The considerable genetic distance of d = 0.074 between P. neptuni and Strobilidium caudatum corroborated the morphological differences and thus the maintenance of the genus Pelagostrobilidium. Strombidium biarmatum nov. spec. is a typical member of the genus, except for the two types of Extrusomes (“trichites”): ∼12×0.5 μm, needle-shaped ones attached anterior to the girdle kinety and ∼6×0.5 μm, rod-shaped ones at the distal end of the intermembranellar ridges. Its flask-shaped resting cysts have several strong spines. In accordance with the morphologic data, S. biarmatum is placed within the order Oligotrichida by gene sequence analysis. The great genetic distances within the oligotrichids support the diversity found in morphologic and ontogenetic studies.
Khaled A S Alrasheid - One of the best experts on this subject based on the ideXlab platform.
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biodiversity of oligotrich ciliates in the south china sea description of three new strombidium species protozoa ciliophora oligotrichia with phylogenetic analyses
Systematics and Biodiversity, 2015Co-Authors: Wen Song, Weibo Song, Khaled A S Alrasheid, Xiaolu Zhao, Weiwei Liu, Saleh A Alfarraj, Alan WarrenAbstract:The morphology and small subunit ribosomal RNA (SSU rRNA) gene sequences of three new species of ciliates in the genus Strombidium are recorded: S. paracapitatum sp. nov., S. cuneiforme sp. nov., and S. caudispina sp. nov. Strombidium paracapitatum sp. nov. is characterized by having a prominent and transparent apical protrusion and two types of Extrusomes. Strombidium cuneiforme sp. nov. differs from its congeners in the combination of its long conical body shape, eyespot and elongated tail. Strombidium caudispina sp. nov. is recognized by its posterior spine and short ventral kinety. In SSU rRNA gene trees, all members of the genus Strombidium cluster into three separate groups. The first group is composed of nine Strombidium species including S. cuneiforme sp. nov., plus Williophrya maedai. The second group consists of S. paracapitatum sp. nov., S. caudispina sp. nov. and three congeners. The third group comprises S. conicum and S. chlorophilum.http://zoobank.org/urn:lsid:zoobank.org:pub:25871A6B-772A-...
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morphology and ssu rrna gene sequences of three marine ciliates from yellow sea china including one new species uronema heteromarinum nov spec ciliophora scuticociliatida
Acta Protozoologica, 2010Co-Authors: J Huang, Khaled A S Alrasheid, Xiaozhong Hu, Weibo SongAbstract:The morphology, infraciliature, and silverline system of three marine scuticociliates, Uronema marinum Dujardin, 1841, U. heteromarinum nov. spec. and Pleuronema setigerum Calkins, 1902, isolated from coastal waters off Qingdao, China, were investigated using living observation and silver impregnation methods. Due to the great confusion in the species definition of the well-known species U. marinum, we have documented a detailed discussion/comparison and believe that most of the confusion is due to the fact that at least 2 closely-related sibling morphotypes exist which are often not recognized. Based on the data available, U. marinum is strictly defined as follows: marine Uronema ca. 30 × 10 μm in size, with truncated apical frontal plate and smooth pellicle, Extrusomes inconspicuous, cytostome located equatorially, 12-14 somatic kineties and one contractile vacuole pore near posterior end of kinety 2. Uronema heteromarinum nov. spec. resembles U. marinum but can be distinguished morphologically by its notched pellicle with conspicuous Extrusomes and reticulate ridges, the 15-16 somatic kineties, widely separated membranelle 1 and membranelle 2, as well as the subequatorially positioned cytostome. Based on the Qingdao population, an improved diagnosis for the poorly known Pleuronema setigerum is: marine slender oval-shaped form, in vivo about 40-50 x 15-20 μm; 3-5 preoral kineties and 14-22 somatic kineties; membranelle 1 and 3 three-rowed, and posterior end of M2a ring-like. The small subunit (SSU) rRNA gene for all three organisms were sequenced and analyzed with standard methods.
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notes on soil ciliates protozoa ciliophora from the netherlands with description of keronopsis schminkei nov spec and apobryophyllum schmidingeri nov spec
Acta Protozoologica, 2007Co-Authors: Wilhelm Foissner, Khaled A S AlrasheidAbstract:Summary. Fifty-six ciliate taxa, including three new species, were found in two soil samples from the Hoge Veluwe National Park in The Netherlands. A literature search showed that The Netherlands, Belgium and Denmark are terra incognita with respect to soil ciliates: only about 100 species have been recorded. Likely, a much greater number, including many undescribed species, can be found on more detailed investigations. Two of the three new species are described in detail. Keronopsis schminkei nov. spec. differs from the congeners by the nuclear apparatus and cirral pattern. Keronopsis wetzeli Wenzel, 1953 is neotypified with the Austrian population described by Berger and Foissner (1987). Apobryophyllum schmidingeri differs from the congeners by body shape, the macronucleus pattern (many nodules), the arrangement of the Extrusomes, and various morphometric features. Scanning electron micrographs and protargol preparations of Enchelys polynucleata confirm earlier transmission electron microscopic data on the occurrence of oralized somatic monokinetids and the lack of a circumoral kinety. Extrusome length and morphology of the resting cysts are rather different in various populations of E. polynucleata, indicating high genetic diversity (subspecies?).
Sebastian Hess - One of the best experts on this subject based on the ideXlab platform.
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ultrastructure of the algivorous amoeboflagellate viridiraptor invadens glissomonadida cercozoa
Protist, 2014Co-Authors: Sebastian Hess, Michael MelkonianAbstract:The family Viridiraptoridae represents a morphologically and ecologically distinct lineage of glissomonad flagellates (Cercozoa, Rhizaria). It currently comprises two highly specialised, algivorous genera inhabiting freshwater ecosystems, Orciraptor and Viridiraptor, for which ultrastructural data were lacking. In this study, the ultrastructure of Viridiraptor invadensHess et Melkonian, the sole described species of the viridiraptorid type genus, has been studied by transmission and scanning electron microscopy. In particular the flagellar transitional region and basal apparatus, both reconstructed from serial sections, revealed ultrastructural traits, that agree with the phylogenetic placement of the viridiraptorids within Glissomonadida: The transitional region contains a distal plate/collar complex and the basal apparatus comprises two ventral posterior roots and an anterior root, all known from other glissomonads. However, two additional small microtubular roots, two conspicuous rhizoplasts and probasal bodies present during interphase represent novel characteristics. Furthermore, an acorn/V-shaped filament system was discovered at the proximal end of the flagellar transitional region and used to establish a basal body triplet numbering system for flagellate cells of the Rhizaria. Finally, ultrastructural data on perforated algal cell walls suggest that the previously described reticulocyst of Viridiraptor represents an Extrusome-derived, mesh-like coat supporting the invasion/feeding process.
