Pub Date : 2025-06-01Epub Date: 2025-04-14DOI: 10.1016/j.protis.2025.126101
Takashi Shiratori, Ken-ichiro Ishida
Endomyxa comprises a diverse group of protists, including free-living amoebae and parasites, that infect various hosts. In this study, we report a new free-living amoeboflagellate, Viscidocauda repens gen. Nov., sp. nov., isolated from seawater near Hachijojima Island, Japan. V. repens is a gliding bacterivorous biflagellate and occasionally extends pseudopodia from its posterior end. Molecular phylogenetic analysis based on small subunit ribosomal RNA gene sequences places V. repens as sister lineage to a clade comprising the endomyxan Ascetosporea and Gromiidea. Ultrastructural observations revealed that V. repens has four microtubular roots (R1–R4), but lacks vp2, a unique microtubular band widely distributed among cercozoan flagellates. Based on its morphology, ultrastructure, and phylogenetic position, we propose V. repens as a new genus and species within Endomyxa.
Endomyxa由多种多样的原生生物组成，包括自由生活的变形虫和寄生虫，它们感染各种宿主。在这项研究中，我们报道了一种新的自由生活的变形虫鞭毛虫，粘尾虫repens gen. Nov., sp. Nov.，从日本八丈岛附近的海水中分离出来。双鞭毛虫是一种滑翔的菌食性双鞭毛虫，偶尔从其后端伸出假足。基于小亚基核糖体RNA基因序列的分子系统发育分析表明，V. repens是由endoomyxan Ascetosporea和Gromiidea组成的分支的姐妹谱系。超微结构观察显示，长尾草有4根微管根（R1-R4），但缺乏广泛分布于尾虫鞭毛类动物的独特微管带vp2。根据其形态、超微结构和系统发育位置，我们提出了一种新的属和种。
{"title":"A novel free-living endomyxan flagellate Viscidocauda repens gen. Nov., sp. nov","authors":"Takashi Shiratori, Ken-ichiro Ishida","doi":"10.1016/j.protis.2025.126101","DOIUrl":"10.1016/j.protis.2025.126101","url":null,"abstract":"<div><div>Endomyxa comprises a diverse group of protists, including free-living amoebae and parasites, that infect various hosts. In this study, we report a new free-living amoeboflagellate, <em>Viscidocauda repens</em> gen. Nov., sp. nov., isolated from seawater near Hachijojima Island, Japan. <em>V. repens</em> is a gliding bacterivorous biflagellate and occasionally extends pseudopodia from its posterior end. Molecular phylogenetic analysis based on small subunit ribosomal RNA gene sequences places <em>V. repens</em> as sister lineage to a clade comprising the endomyxan Ascetosporea and Gromiidea. Ultrastructural observations revealed that <em>V. repens</em> has four microtubular roots (R1–R4), but lacks vp2, a unique microtubular band widely distributed among cercozoan flagellates. Based on its morphology, ultrastructure, and phylogenetic position, we propose <em>V. repens</em> as a new genus and species within Endomyxa.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"177 ","pages":"Article 126101"},"PeriodicalIF":1.9,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-01Epub Date: 2025-05-03DOI: 10.1016/j.protis.2025.126103
Robert E. Jones , Quentin Blandenier , Felicity Kleitz-Singleton , Tristan C. Henderson , Nicholas W. Fry , Idan Banson , Jonah Nguyen , Alexander K. Tice , Matthew W. Brown
Three major groups of primarily amoeboid taxa are present across Amoebozoa: Discosea, Evosea, and Tubulinea. While each of these groups were thought to have morphologically unique traits and members, the morphologic boundaries between each group have recently blurred. For example, it is demonstrated that several taxa in each group display monopodial limax amoebae, a characteristic most often associated with Tubulinea. Here we describe a novel discosean amoeba isolated from a freshwater pond, Janelia veilia n. gen. n. sp. Its cells have variable morphologies, but often display monopodial limax amoebae, with a unique trailing structure that appears to be derived from cellular material. In some cases, cells have conical pseudopodia or pointed pseudopodia. Using phylogenomics, we find that this taxon branches as sister to the recently described discosean Mycamoeba gemmipara and the sporocarpic protosteloid amoeba Microglomus paxillus, forming an order-level group we term Mycamoebida. Mycamoebida is fully supported as sister to Dermamoebida, together forming a subclass we term Dermelia. SSU rRNA phylogenies show that Janelia veilia n. gen. n. sp. is molecularly unique from any known organism, but branches with high support in a clade containing Mycamoeba gemmipara and several environmental sequences suggesting a larger diverse clade within Discosea.
主要变形虫类群有三个主要类群：盘状变形虫、进化变形虫和管状变形虫。虽然这些群体中的每一个都被认为在形态上有独特的特征和成员，但每一个群体之间的形态界限最近变得模糊了。例如，每个类群中都有几个类群表现出单足最大变形虫，这一特征通常与管线型有关。本文描述了一种从淡水池塘中分离出来的新型盘状变形虫，Janelia veilia n. gen. n. sp.它的细胞形态多样，但通常表现为单足极限变形虫，具有独特的尾随结构，似乎来源于细胞物质。在某些情况下，细胞有圆锥形或尖状伪足。利用系统基因组学，我们发现这个分类单元分支是最近被描述的盘状Mycamoeba gemmipara和孢子生的原柱状阿米巴Microglomus paxillus的姐妹，形成了一个我们称之为Mycamoebida的目级类群。Mycamoebida是Dermamoebida的姐妹，它们共同形成了一个亚类，我们称之为Dermelia。SSU rRNA系统发育表明，紫花紫花在分子上与任何已知的生物都是独特的，但在含有双足支原体的分支中具有高支持度，并且一些环境序列表明在Discosea中存在更大的多样性分支。
{"title":"Piercing the veil: A novel amoebozoan (Janelia veilia n. gen. n. sp.) reveals deep clades within Discosea through phylogenomics","authors":"Robert E. Jones , Quentin Blandenier , Felicity Kleitz-Singleton , Tristan C. Henderson , Nicholas W. Fry , Idan Banson , Jonah Nguyen , Alexander K. Tice , Matthew W. Brown","doi":"10.1016/j.protis.2025.126103","DOIUrl":"10.1016/j.protis.2025.126103","url":null,"abstract":"<div><div>Three major groups of primarily amoeboid taxa are present across Amoebozoa: Discosea, Evosea, and Tubulinea. While each of these groups were thought to have morphologically unique traits and members, the morphologic boundaries between each group have recently blurred. For example, it is demonstrated that several taxa in each group display monopodial limax amoebae, a characteristic most often associated with Tubulinea. Here we describe a novel discosean amoeba isolated from a freshwater pond, <em>Janelia veilia</em> n. gen. n. sp. Its cells have variable morphologies, but often display monopodial limax amoebae, with a unique trailing structure that appears to be derived from cellular material. In some cases, cells have conical pseudopodia or pointed pseudopodia. Using phylogenomics, we find that this taxon branches as sister to the recently described discosean <em>Mycamoeba gemmipara</em> and the sporocarpic protosteloid amoeba <em>Microglomus paxillus</em>, forming an order-level group we term Mycamoebida. Mycamoebida is fully supported as sister to Dermamoebida, together forming a subclass we term Dermelia. SSU rRNA phylogenies show that <em>Janelia veilia</em> n. gen. n. sp. is molecularly unique from any known organism, but branches with high support in a clade containing <em>Mycamoeba gemmipara</em> and several environmental sequences suggesting a larger diverse clade within Discosea.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"177 ","pages":"Article 126103"},"PeriodicalIF":1.9,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-01Epub Date: 2025-03-19DOI: 10.1016/j.protis.2025.126098
Lou Mary , Marie Latimier , Joelle Serghine , Julien Quere , Véronique Savar , Sébastien Artigaud , Damien Réveillon , Mickael Le Gac , Cécile Jauzein , Hélène Hégaret
Dinoflagellates of the genus Alexandrium can produce bioactive extracellular compounds (BECs) responsible for a wide range of effects on many organisms. These compounds are poorly characterized within the genus Alexandrium. The transmission of the allelopathic phenotype within the recombinant progeny in dinoflagellates has not been documented either. This study investigated the effects of these allelochemicals produced by two parental strains of the dinoflagellate Alexandrium minutum and their 14 recombinant progeny against two targets, the diatom Chaetoceros muelleri and the dinoflagellate parasite Amoebophrya sp.. Analyses by flow cytometry on proxy parameters of cell physiology revealed that the allelochemicals produced by 15 out of 16 strains appear to induce deleterious effects on the photosynthetic apparatus of C. muelleri as well as on cell size. The cell membranes of C. muelleri were also damaged by the filtrate of 9 strains. Finally, the allelochemicals of 8 A. minutum strains seem to have a deleterious effect on the cell membranes of Amoebophrya sp. dinospore. The deleterious effects against the two targets were correlated. However, they were not correlated with pH, cell size, or paralytic shellfish toxin content. Overall, our results suggest that 1) among the allelochemicals produced by A. minutum, some would have an effect on the same molecular targets in both Amoebophrya sp. and in C. muelleri, 2) specific metabolite production of each strain was responsible for the range of effects observed and 3) the heritability of allelochemical production in A. minutum may involve several genetic loci.
{"title":"Alexandrium minutum strains from a recombinant cross show correlated allelopathic activity against the diatom Chaetoceros muelleri and the parasite Amoebophrya sp., independent of PST toxicity.","authors":"Lou Mary , Marie Latimier , Joelle Serghine , Julien Quere , Véronique Savar , Sébastien Artigaud , Damien Réveillon , Mickael Le Gac , Cécile Jauzein , Hélène Hégaret","doi":"10.1016/j.protis.2025.126098","DOIUrl":"10.1016/j.protis.2025.126098","url":null,"abstract":"<div><div>Dinoflagellates of the genus <em>Alexandrium</em> can produce bioactive extracellular compounds (BECs) responsible for a wide range of effects on many organisms. These compounds are poorly characterized within the genus <em>Alexandrium</em>. The transmission of the allelopathic phenotype within the recombinant progeny in dinoflagellates has not been documented either. This study investigated the effects of these allelochemicals produced by two parental strains of the dinoflagellate <em>Alexandrium minutum</em> and their 14 recombinant progeny against two targets, the diatom <em>Chaetoceros muelleri</em> and the dinoflagellate parasite <em>Amoebophrya</em> sp.. Analyses by flow cytometry on proxy parameters of cell physiology revealed that the allelochemicals produced by 15 out of 16 strains appear to induce deleterious effects on the photosynthetic apparatus of <em>C. muelleri</em> as well as on cell size. The cell membranes of <em>C. muelleri</em> were also damaged by the filtrate of 9 strains. Finally, the allelochemicals of 8 <em>A. minutum</em> strains seem to have a deleterious effect on the cell membranes of <em>Amoebophrya</em> sp. dinospore. The deleterious effects against the two targets were correlated. However, they were not correlated with pH, cell size, or paralytic shellfish toxin content. Overall, our results suggest that 1) among the allelochemicals produced by <em>A. minutum</em>, some would have an effect on the same molecular targets in both <em>Amoebophrya</em> sp. and in <em>C. muelleri</em>, 2) specific metabolite production of each strain was responsible for the range of effects observed and 3) the heritability of allelochemical production in <em>A. minutum</em> may involve several genetic loci.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"177 ","pages":"Article 126098"},"PeriodicalIF":1.9,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-02-03DOI: 10.1016/j.protis.2025.126087
Nicole L. Coots, Daniel E. Jasso-Selles, Kali L. Swichtenberg, Serena G. Aguilar, LeAnn Nguyen, Piper G. Sidles, Cindy Woo, Harrison M. Smith, Bailey J. Bresee, Amir A. Abboud, Tala Abd Al Rahman, Ritika Anand, Sergio R. Avalle, Anuvi Batra, Mackenzie A. Brown, Hilary Camacho Ruelas, Alfanarely Fajardo Chavez, Campbell N. Gallegos, Amalia Grambs, D. Armaan Hernández, Gillian H. Gile
Wood-feeding termites harbor specialized protists in their hindguts in a classic nutritional mutualism. The protists are vertically inherited, which has generated a broad-scale pattern of codiversification over ∼150 million years, but there are many incongruences due to lineage-specific loss and transfer of symbionts. Despite the evolutionary and economic importance of this symbiosis, the symbiont communities of most termite species are incompletely characterized or entirely unstudied. Here, we have investigated the protist symbiont community of Reticulitermes tibialis, using single-cell PCR to link morphology to 18S rRNA gene sequences. The protists belong to at least 41 species in 3 major lineages within Metamonada: Spirotrichonymphida, Pyrsonymphidae, and Trichonympha. The Spirotrichonymphida symbionts belong to 6 genera, including Pseudospironympha, which has not been found in Reticulitermes until now, and Dexiohelix, a new genus. Pyrsonymphidae traditionally include just Pyrsonympha and Dinenympha, but our morphology-linked 18S phylogeny indicates that both genera are polyphyletic. We accordingly restrict the definitions of Pyrsonympha and Dinenympha to the clades that include their type species, and we propose 5 new genera to accommodate the remaining clades. Short-read 18S amplicon sequencing revealed considerable variation in community composition across R. tibialis colonies in Arizona, suggestive of a symbiont metacommunity. Symbiont species varied in their prevalence across colonies, with a core set of about 12 highly prevalent symbiont species, 11 species with intermediate prevalence, and 18 rare species. This pattern contrasts with the traditional paradigm of consistent symbiont community composition across colonies of a termite species.
{"title":"The protist symbionts of Reticulitermes tibialis: Unexpected diversity enables a new taxonomic framework","authors":"Nicole L. Coots, Daniel E. Jasso-Selles, Kali L. Swichtenberg, Serena G. Aguilar, LeAnn Nguyen, Piper G. Sidles, Cindy Woo, Harrison M. Smith, Bailey J. Bresee, Amir A. Abboud, Tala Abd Al Rahman, Ritika Anand, Sergio R. Avalle, Anuvi Batra, Mackenzie A. Brown, Hilary Camacho Ruelas, Alfanarely Fajardo Chavez, Campbell N. Gallegos, Amalia Grambs, D. Armaan Hernández, Gillian H. Gile","doi":"10.1016/j.protis.2025.126087","DOIUrl":"10.1016/j.protis.2025.126087","url":null,"abstract":"<div><div>Wood-feeding termites harbor specialized protists in their hindguts in a classic nutritional mutualism. The protists are vertically inherited, which has generated a broad-scale pattern of codiversification over ∼150 million years, but there are many incongruences due to lineage-specific loss and transfer of symbionts. Despite the evolutionary and economic importance of this symbiosis, the symbiont communities of most termite species are incompletely characterized or entirely unstudied. Here, we have investigated the protist symbiont community of <em>Reticulitermes tibialis,</em> using single-cell PCR to link morphology to 18S rRNA gene sequences. The protists belong to at least 41 species in 3 major lineages within Metamonada: Spirotrichonymphida, Pyrsonymphidae, and <em>Trichonympha</em>. The Spirotrichonymphida symbionts belong to 6 genera, including <em>Pseudospironympha</em>, which has not been found in <em>Reticulitermes</em> until now, and <em>Dexiohelix</em>, a new genus. Pyrsonymphidae traditionally include just <em>Pyrsonympha</em> and <em>Dinenympha</em>, but our morphology-linked 18S phylogeny indicates that both genera are polyphyletic. We accordingly restrict the definitions of <em>Pyrsonympha</em> and <em>Dinenympha</em> to the clades that include their type species, and we propose 5 new genera to accommodate the remaining clades. Short-read 18S amplicon sequencing revealed considerable variation in community composition across <em>R. tibialis</em> colonies in Arizona, suggestive of a symbiont metacommunity. Symbiont species varied in their prevalence across colonies, with a core set of about 12 highly prevalent symbiont species, 11 species with intermediate prevalence, and 18 rare species. This pattern contrasts with the traditional paradigm of consistent symbiont community composition across colonies of a termite species.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"176 ","pages":"Article 126087"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143372666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-02-14DOI: 10.1016/j.protis.2025.126089
William Bourland, Ivan Čepička
The ciliate genus Malacophrys has been incertae sedis for more than 50 years in what is now subphylum Intramacronucleata, provisionally assigned to three different classes by various authors. Of the three species included in the genus, M. sphagni and the type species, Malacophrys rotans, have not been studied by modern methods and M. viridis, although morphologically well-described, lacks molecular characterization. We identified two freshwater ciliates as morphologically consistent with two members of Malacophrys, namely M. rotans and M. viridis. We studied one population of M. rotans, using in vivo observation and silver carbonate and silver nitrate impregnation, and two populations of M. viridis, using in vivo observation, silver carbonate impregnation, and 18S rRNA gene sequencing. Phylogenetic analyses strongly support the position of M. viridis in the class Oligohymenophorea. Morphologic features suggest Malacophrys rotans belongs to order Tetrahymenida, but a confident phylogenetic assignment awaits its molecular sequencing. Differences between their oral structures and silverline patterns indicate that M. rotans and M. viridis likely belong to different genera. A formal separation at the genus level awaits molecular characterization of the type species, M. rotans.
{"title":"The enigmatic genus Malacophrys Kahl, 1926 (Ciliophora: Intramacronucleata) belongs to the class Oligohymenophorea","authors":"William Bourland, Ivan Čepička","doi":"10.1016/j.protis.2025.126089","DOIUrl":"10.1016/j.protis.2025.126089","url":null,"abstract":"<div><div>The ciliate genus <em>Malacophrys</em> has been incertae sedis for more than 50 years in what is now subphylum Intramacronucleata, provisionally assigned to three different classes by various authors. Of the three species included in the genus, <em>M. sphagni</em> and the type species, <em>Malacophrys rotans</em>, have not been studied by modern methods and <em>M. viridis</em>, although morphologically well-described, lacks molecular characterization. We identified two freshwater ciliates as morphologically consistent with two members of <em>Malacophrys</em>, namely <em>M. rotans</em> and <em>M. viridis</em>. We studied one population of <em>M. rotans</em>, using in vivo observation and silver carbonate and silver nitrate impregnation, and two populations of <em>M. viridis</em>, using in vivo observation, silver carbonate impregnation, and 18S rRNA gene sequencing. Phylogenetic analyses strongly support the position of <em>M. viridis</em> in the class Oligohymenophorea. Morphologic features suggest <em>Malacophrys rotans</em> belongs to order Tetrahymenida, but a confident phylogenetic assignment awaits its molecular sequencing. Differences between their oral structures and silverline patterns indicate that <em>M. rotans</em> and <em>M. viridis</em> likely belong to different genera. A formal separation at the genus level awaits molecular characterization of the type species, <em>M. rotans</em>.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"176 ","pages":"Article 126089"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Morphology of seven chrysophycean stomatocysts was studied using scanning electron microscopy. All stomatocysts were recorded from the shallow lakes located in the Steppe zone of South Urals. Four morphotypes (stomatocyst 373 Taylor et Smol, stomatocyst 68 Van de Vijver et Beyens, stomatocyst 99 Pang et Wang and stomatocyst 101 Pang et Wang Forma B) are rare and reported for the first time in Russia. New observations on the formation of the cyst ornamentation allowed us to amend the descriptions of two morphotypes. Three stomatocysts are described as new to science. Morphological variability of all seven morphotypes are illustrated and discussed.
用扫描电镜观察了7个菊花藻口囊的形态。所有口囊均来自南乌拉尔草原区浅水湖泊。四种形态（口囊373 Taylor et Smol，口囊68 Van de Vijver et Beyens，口囊99 Pang et Wang和口囊101 Pang et Wang Forma B）在俄罗斯罕见且首次报道。对囊肿纹饰形成的新观察使我们能够修正两种形态的描述。三种口囊肿被描述为科学上的新事物。所有七种形态型的形态变异都被说明和讨论。
{"title":"New and noteworthy chrysophycean stomatocysts from the Steppe zone of South Urals (Russia) with comments on the morphological variability","authors":"Marina Ignatenko , Tatyana Yatsenko-Stepanova , Dmitry Kapustin","doi":"10.1016/j.protis.2024.126075","DOIUrl":"10.1016/j.protis.2024.126075","url":null,"abstract":"<div><div>Morphology of seven chrysophycean stomatocysts was studied using scanning electron microscopy. All stomatocysts were recorded from the shallow lakes located in the Steppe zone of South Urals. Four morphotypes (stomatocyst 373 Taylor et Smol, stomatocyst 68 Van de Vijver et Beyens, stomatocyst 99 Pang et Wang and stomatocyst 101 Pang et Wang <em>Forma B</em>) are rare and reported for the first time in Russia. New observations on the formation of the cyst ornamentation allowed us to amend the descriptions of two morphotypes. Three stomatocysts are described as new to science. Morphological variability of all seven morphotypes are illustrated and discussed.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"176 ","pages":"Article 126075"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142771610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2024-12-24DOI: 10.1016/j.protis.2024.126084
Seung-Hyeon Kim , S.D.N.K. Bathige , Donghyun Lee , W.A.A.H. Kalhari , Hyoun Joong Kim , Kyung-Il Park
This study discovered the first Asian population of Sphaeroforma nootkatensis (SphX), a member of Mesomycetozoea, in the southern coastal region of South Korea. Although investigating parasites in Pacific oysters (Crassostrea gigas), a single-cell microorganism was isolated from gill tissues. Comprehensive phylogenetic analysis of its 18S rDNA revealed its placement within the order Ichthyophonida, class Mesomycetozoea. SphX formed a distinct cluster within Sphaeroforma spp., separate from Pseudoperkinsus tapetis. Morphological examinations of in vitro cultured cells revealed two distinctive life stages characterized by multilobe and granular sporangium, accompanied by corresponding non-motile larger and motile smaller endospores, respectively. Scanning electron microscope analysis depicted lobular and smooth surfaces on vegetative cells, indicative of differing life cycle stages. Transmission electron microscope observations revealed intriguing features consistent with previous reports on Mesomycetozoea. A prominent fibrillar structure was noted in a vegetative cell. In contrast, smaller endospores were observed with cilia-like structures surrounding the cell wall, indicating their mode of movement. The Ray's fluid thioglycollate medium assay showed that SphX cells were digested, whereas some small endospores remained resistant. This discovery provides novel insights into the life stages of Mesomycetozoans and geographical distribution and underscores the importance of monitoring oyster health for effective aquaculture management.
{"title":"Molecular phylogeny, morphology, and ultrastructure of a Mesomycetozoea member, Sphaeroforma nootkatensis isolated from Pacific oyster, Crassostrea gigas, on the Southern coast of Korea","authors":"Seung-Hyeon Kim , S.D.N.K. Bathige , Donghyun Lee , W.A.A.H. Kalhari , Hyoun Joong Kim , Kyung-Il Park","doi":"10.1016/j.protis.2024.126084","DOIUrl":"10.1016/j.protis.2024.126084","url":null,"abstract":"<div><div>This study discovered the first Asian population of <em>Sphaeroforma nootkatensis</em> (SphX), a member of Mesomycetozoea, in the southern coastal region of South Korea. Although investigating parasites in Pacific oysters (<em>Crassostrea gigas</em>), a single-cell microorganism was isolated from gill tissues. Comprehensive phylogenetic analysis of its 18S rDNA revealed its placement within the order Ichthyophonida, class Mesomycetozoea. SphX formed a distinct cluster within <em>Sphaeroforma</em> spp., separate from <em>Pseudoperkinsus tapetis</em>. Morphological examinations of in vitro cultured cells revealed two distinctive life stages characterized by multilobe and granular sporangium, accompanied by corresponding non-motile larger and motile smaller endospores, respectively. Scanning electron microscope analysis depicted lobular and smooth surfaces on vegetative cells, indicative of differing life cycle stages. Transmission electron microscope observations revealed intriguing features consistent with previous reports on Mesomycetozoea. A prominent fibrillar structure was noted in a vegetative cell. In contrast, smaller endospores were observed with cilia-like structures surrounding the cell wall, indicating their mode of movement. The Ray's fluid thioglycollate medium assay showed that SphX cells were digested, whereas some small endospores remained resistant. This discovery provides novel insights into the life stages of Mesomycetozoans and geographical distribution and underscores the importance of monitoring oyster health for effective aquaculture management.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"176 ","pages":"Article 126084"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142915088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-01-20DOI: 10.1016/j.protis.2025.126086
Hitoshi Iida
Stentor pyriformis is a unicellular organism whose inherent green-algal symbionts can be utilized in evolutionary and cytological studies. The cytoplasm contains symbiotic algae and starch granules, which are in constant motion. The habitats of the ciliate S. pyriformis are restricted to a few oligotrophic ponds in Japan. This study aimed to develop a culture medium for long-term incubation based on pond water quality data and to investigate the cytoplasmic streaming of symbiotic algae and starch granules in S. pyriformis. In addition, the involvement of the cytoskeleton and motor proteins in cytoplasmic streaming was examined using microtubule polymerization and dynein ATPase inhibitors. The results indicated that the cytoplasmic streaming in S. pyriformis is associated with the microtubule system. Immunofluorescence and transmission electron microscopy revealed the presence of KM-fibers, bundles of microtubules running longitudinally along the cell surface. These findings suggest a possible link between microtubules and cytoplasmic streaming in S. pyriformis.
{"title":"Cytoplasmic streaming of symbiotic algae in the ciliate Stentor pyriformis","authors":"Hitoshi Iida","doi":"10.1016/j.protis.2025.126086","DOIUrl":"10.1016/j.protis.2025.126086","url":null,"abstract":"<div><div><em>Stentor pyriformis</em> is a unicellular organism whose inherent green-algal symbionts can be utilized in evolutionary and cytological studies. The cytoplasm contains symbiotic algae and starch granules, which are in constant motion. The habitats of the ciliate <em>S. pyriformis</em> are restricted to a few oligotrophic ponds in Japan. This study aimed to develop a culture medium for long-term incubation based on pond water quality data and to investigate the cytoplasmic streaming of symbiotic algae and starch granules in <em>S. pyriformis</em>. In addition, the involvement of the cytoskeleton and motor proteins in cytoplasmic streaming was examined using microtubule polymerization and dynein ATPase inhibitors. The results indicated that the cytoplasmic streaming in <em>S. pyriformis</em> is associated with the microtubule system. Immunofluorescence and transmission electron microscopy revealed the presence of KM-fibers, bundles of microtubules running longitudinally along the cell surface. These findings suggest a possible link between microtubules and cytoplasmic streaming in <em>S. pyriformis.</em></div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"176 ","pages":"Article 126086"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143047707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2024-11-27DOI: 10.1016/j.protis.2024.126072
David J.S. Montagnes
{"title":"Protists and Society: A report on the 2024 autumn meeting of Protistology-UK, at the natural history museum, London","authors":"David J.S. Montagnes","doi":"10.1016/j.protis.2024.126072","DOIUrl":"10.1016/j.protis.2024.126072","url":null,"abstract":"","PeriodicalId":20781,"journal":{"name":"Protist","volume":"176 ","pages":"Article 126072"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-01-17DOI: 10.1016/j.protis.2025.126085
Juan J. Ginés-Rivas, Martin Carr
Choanoflagellate species have been taxonomically divided upon the morphological and developmental basis of their extracellular coat (periplast). Species within the order Craspedida possess a purely organic periplast, whereas taxa of the order Acanthoecida have an additional silica based periplast termed the lorica. Whilst small-scale phylogenetic studies have recovered the two orders as monophyletic, recent phylogenomic analyses have rejected the monophyly of the craspedids. These analyses suggest that the freshwater craspedid Codosiga hollandica falls within the earliest branching choanoflagellate lineage; however, it has also been noted that phylogenomic studies result in inconsistent phylogenies, with unstable long-branched species being recovered as basal choanoflagellates. Presented here are phylogenetic analyses, based upon slowly evolving ribosomal proteins, which consistently recover both craspedid monophyly and a derived placement of C. hollandica. The addition of further, long-branched, ribosomal proteins to phylogenetic analyses are shown to generate longer terminal branches and a weakening of the support for Craspedida. The analyses highlight the requirement for an increase in data, in terms of both taxa and gene coverage, to successfully resolve the earliest craspedid branches. In addition, phylogenetically unstable species are identified that are recommended to be omitted from phylogenomic studies as they have the potential to disrupt recovered relationships.
{"title":"Slowly evolving proteins support the monophyly of Craspedida (Choanoflagellatea) and a marine origin of choanoflagellates","authors":"Juan J. Ginés-Rivas, Martin Carr","doi":"10.1016/j.protis.2025.126085","DOIUrl":"10.1016/j.protis.2025.126085","url":null,"abstract":"<div><div>Choanoflagellate species have been taxonomically divided upon the morphological and developmental basis of their extracellular coat (periplast). Species within the order Craspedida possess a purely organic periplast, whereas taxa of the order Acanthoecida have an additional silica based periplast termed the lorica. Whilst small-scale phylogenetic studies have recovered the two orders as monophyletic, recent phylogenomic analyses have rejected the monophyly of the craspedids. These analyses suggest that the freshwater craspedid <em>Codosiga hollandica</em> falls within the earliest branching choanoflagellate lineage; however, it has also been noted that phylogenomic studies result in inconsistent phylogenies, with unstable long-branched species being recovered as basal choanoflagellates. Presented here are phylogenetic analyses, based upon slowly evolving ribosomal proteins, which consistently recover both craspedid monophyly and a derived placement of <em>C. hollandica</em>. The addition of further, long-branched, ribosomal proteins to phylogenetic analyses are shown to generate longer terminal branches and a weakening of the support for Craspedida. The analyses highlight the requirement for an increase in data, in terms of both taxa and gene coverage, to successfully resolve the earliest craspedid branches. In addition, phylogenetically unstable species are identified that are recommended to be omitted from phylogenomic studies as they have the potential to disrupt recovered relationships.</div></div>","PeriodicalId":20781,"journal":{"name":"Protist","volume":"176 ","pages":"Article 126085"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143028971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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