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Laure Guillou - One of the best experts on this subject based on the ideXlab platform.
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Wide genetic diversity of picoplanktonic green algae (Chloroplastida) in the Mediterranean Sea uncovered by a phylum-biased PCR approach.
Environmental microbiology, 2008Co-Authors: Manon Viprey, Laure Guillou, Martial Ferréol, Daniel VaulotAbstract:Summary The genetic diversity of picoplanktonic (i.e. cells that can pass through a 3 mm pore-size filter) green algae was investigated in the Mediterranean Sea in late summer by a culture-independent approach. Genetic libraries of the 18S rRNA gene were constructed using two different primer sets. The first set is com- monly used to amplify the majority of eukaryotic lin- eages, while the second was composed of a general eukaryotic forward primer and a reverse primer biased towards the phylum Chloroplastida. A total of 3980 partial environmental sequences were obtained: 1668 using the general eukaryotic primer set and 2312 using the Chloroplastida-biased primer set. Of these sequences, 65 (4%) and 594 (26%) belonged to the Chloroplastida respectively. A 99.5% sequence simi- larity cut-off value allowed classification of these 659 Chloroplastida sequences into 74 different opera- tional taxonomic units. A majority of the Chloroplas- tida sequences (99%) belonged to the prasinophytes. In addition to the seven independent prasinophyte lineages previously described, we discovered two new clades (clades VIII and IX), as well as a significant genetic diversity at the species and subspecies levels, notably among the genera Crustomastix, Doli- chomastix and Mamiella (Mamiellales), but also within Pyramimonas and Halosphaera (Pyramimonadales). Such diversity within prasinophytes has not previ- ously been observed by cloning approaches, illustrat- ing the power of using targeted primers for clone library construction. Prasinophyte assemblages dif- fered especially in relation to nutrient levels. Micro- monas and Ostreococcus were mainly recovered from mesotrophic areas, whereas Mamiella, Crusto- mastix and Dolichomastix were mostly detected in oligotrophic surface waters. Within genera such as Ostreococcus or Crustomastix for which several clades were observed, depth seemed to be the main factor controlling differential distribution of genotypes.
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Pigment suites and taxonomic groups in Prasinophyceae
Journal of Phycology, 2004Co-Authors: Mikel Latasa, Renate Scharek, Florence Le Gall, Laure GuillouAbstract:Pigment analysis performed on 30 Prasinophyceae strains revealed two main groups: the prasinoxanthin-containing and prasinoxanthinless Prasinophyceae. Prasinoxanthin-containing Prasinophyceae comprised the orders Mamiellales, Pseudoscourfieldiales (Pycnococcaceae), and Prasinococcales. For this group, classification with pigment composition showed a good agreement with molecular phylogeny. Mamiellales, except Crustomastix stigmatica, accumulated uriolide, micromonal, dihydrolutein, and the pigment Unidentified M1 as characteristic pigments. Prasinococcales and Pseudoscourfieldiales (Pycnococcaceae) lacked micromonal and Unidentified M1. In addition, Pseudoscourfieldiales (Pycnococcaceae) lacked uriolide. A chl c3-like pigment was present in prasinoxanthin-containing strains isolated from the deep sea. Common green algae pigments, a loroxanthin derivative, and siphonaxanthin plus derivatives were found in the prasinoxanthinless Prasinophyceae, which included strains from Pyramimonadales, Pseudoscourfieldiales (Nephroselmidiaceae), Chlorodendrales, and a new order. Although some associations could be observed, the correspondence between pigments and molecular taxonomy was less clear for this group.
Michael Krings - One of the best experts on this subject based on the ideXlab platform.
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Microfossils with suggested affinities to the Pyramimonadales (Pyramimonadophyceae, Chlorophyta) from the Lower Devonian Rhynie chert
Acta Palaeobotanica, 2014Co-Authors: Evelyn Kustatscher, Nora Dotzler, Thomas N. Taylor, Michael KringsAbstract:An assemblage of unusual microfossils occurs within an accumulation of plant debris, hyphae, and various types of propagules in the Early Devonian Rhynie chert. Specimens consist of a vesicle with one or more prominent wings (alae) arising from the surface; one wing forms a rim around the equator of the vesicle. The microfossils are interpreted as phycomata of a prasinophycean green alga based on morphological similarities to Pterospermella, a microfossil similar to phycoma stages of the extant Pterosperma (Pyramimonadales). This report represents the third record of phycomata in the Rhynie chert, suggesting that this Early Devonian eco- system served as habitat to a variety of prasinophyte algae. Moreover, the new microfossils add to the inventory of fossil freshwater representatives of this predominantly marine group of algae.
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A prasinophycean alga of the genus Cymatiosphaera in the Early Devonian Rhynie chert
Review of Palaeobotany and Palynology, 2007Co-Authors: Nora Dotzler, Thomas N. Taylor, Michael KringsAbstract:Spherical phycomata of prasinophycean algae are preserved in the Early Devonian Rhynie chert. Because they display a surface reticulum composed of muri oriented perpendicular to the vesicle surface, they are assigned to the genus Cymatiosphaera (Cymatiosphaeraceae, Pyramimonadales). We interpret the size range of the phycomata (24 to 48 μm in overall diameter) as reflecting continued metabolic activity and growth of the alga during the phycoma stage. The phycomata from the Rhynie chert represent the earliest account of the genus Cymatiosphaera in a freshwater paleoecosystem, and broaden our knowledge about the ecological diversity of Early Devonian prasinophycean algae. © 2007 Elsevier B.V. All rights reserved.
Shoichiro Suda - One of the best experts on this subject based on the ideXlab platform.
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Taxonomy and phylogeny of Pyramimonas vacuolata sp. nov. (Pyramimonadales, Chlorophyta)
Phycologia, 2015Co-Authors: Mohammad Azmal Hossain Bhuiyan, Stuart D. Sym, Daphne Georgina Faria, Takeo Horiguchi, Shoichiro SudaAbstract:Abstract: Pyramimonas vacuolata Suda, Horiguchi & Sym sp. nov. is described from Okinawa-jima Island, Japan. The species has been characterized using light and electron microscopy and its phylogenetic position inferred based on 18S rDNA and rbcL gene sequences relative to other species. Strains of P. vacuolata were isolated from coastal sand samples collected from two localities in Okinawa-jima. The cells are quadriflagellate but remarkably large for the genus, and the posterior half of the cell is vacuolated. The single parietal chloroplast is olive-green and contains two conspicuous pyrenoids lying on the same transverse plane, slightly anterior to the equatorial region of the cell. The pyrenoids are surrounded by numerous starch grains, and thylakoids randomly traverse the pyrenoid matrix. Two monolayered eyespots are present, situated on the same transverse plane as the pyrenoids. The alga possesses three types of body scales and four types of flagellar scales, inclusive of two types of hair scales. T...
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genetic diversity of pyramimonas from ryukyu archipelago japan chlorophyceae Pyramimonadales
Journal of Marine Science and Technology, 2013Co-Authors: Shoichiro Suda, Mohammad Azmal Hossain Bhuiyan, Daphne Georgina FariaAbstract:The genus Pyramimonas Schmarda was traditionally described on observations of its periplast and internal structure of different flagellar apparatus or eyespot orientations and currently comprises of ca. 60 species that are divided into six subgenera: Pyramimonas, Vestigifera, Trichocystis, Punctatae, Hexactis, and Macrura. In order to understand the genetic diversity and phylogenetic relationships of genus Pyramimonas members, we analyzed nuclear SSU rDNA molecular data from 41 strains isolated from different locations of the Ryukyu Archipelago. Phylogenetic analyses revealed that strains could be segregated into six clades, four of which represented existing subgenera: Pyramimonas, Vestigifera McFadden, Trichocystis McFadden, and Punctatae McFadden, and two undescribed subgenera. Most recovered subgenera were represented by established and confirmed species of Pyramimonas along with several potentially undescribed species with the exception of one undescribed subgenus. Many of the newly isolated strains were closely related with Pyramimonas aurea and P. olivacea, and were considered to belong to subgenus Punctatae. However, nuclear SSU rDNA phylogenetic trees clearly showed that they are genetically different and can be divided into two subgenera. Subgenus Punctatae comprised of Pyramimonas olivacea and related strains whilst, P. aurea and related strains belonged to an undescribed subgenus which is tentatively referred to as undescribed subgenus 1 which shared a sister-group relationship with subgenus Punctatae. The genetic similarity based on nuclear SSU rDNA ranged from 98.2% to 99.9% and 97.3% to 98.3% within and between subgenera, respectively. The present work shows high level of genetic diversity for the genus Pyramimonas from the Ryukyu Archipelago, Japan.
Bernard Teyssèdre - One of the best experts on this subject based on the ideXlab platform.
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Les algues vertes (phylum Viridiplantae), sont-elles vieilles de deux milliards d'années ?
Carnets de Geologie, 2006Co-Authors: Bernard TeyssèdreAbstract:Bernard TEYSSÈDRE est professeur émérite, ancien directeur d'une unité CNRS/Université de Paris en Sciences Humaines et Sociales. Il a dirigé une école doctorale en Arts et Sciences de l'Art et l'Institut d'Esthétique des Arts contemporains. Docteur en Histoire et en Philosophie, son dessein profond est la quête des sources, celle de notre imaginaire avec ses ouvrages sur la Naissance du Diable et de l'Enfer, de Babylone aux grottes de la Mer Morte ou sur les Anges, les Astres et les Cieux, comme celle des débuts de toute forme de vie. Avec une surprenante fiction politico-romanesque autour du sulfureux tableau de COURBET l'Origine du Monde, pensait-il déjà à l'enquête qu'il allait mener sur les temps oú la vie se cachait, "La vie invisible" oú il passe de l'archéologie de nos croyances à la quête scientifique de nos origines ? Passionné depuis toujours par les Sciences de l'évolution, il possède sur les fossiles et leur descendants des connaissances quasi-encyclopédiques que bien des spécialistes peuvent lui envier. L'étude des trois premiers milliards d'années de l'histoire de la vie est récente et en pleine évolution. 90% des fossiles précambriens ont été découverts depuis moins de 20 ans. Bernard TEYSSÈDRE a intégré dans "La vie invisible" les données de la paléontologie, de la biochimie et de la phylogénie moléculaire. C'est la première synthèse de ce qu'on appelle actuellement la Géologie intégrative. On se prend à apprécier la lecture avec un style dont on a perdu l'habitude, d'un ouvrage que seuls les anglo-saxons semblaient capables de proposer. L'ouvrage présenté ici a pour base un différend qui oppose l'auteur à Andrew KNOLL, qui situe l'apparition des algues vertes vers 750 Ma. Bernard TEYSSÈDRE analyse ce problème par les méthodes qu'il préconisait dans "La vie invisible" combinant à la paléontologie descriptive traditionnelle, les analyses ultrastructurales et biochimiques et confrontant ces résultats avec ceux de la phylogénie moléculaire. Manié avec discernement et compétence, cet outil ne permet certes pas d'établir une taxinomie exacte, mais d'écarter les taxinomies erronées basées sur des convergences et de déterminer la succession des points nodaux dans l'évolution d'une lignée. Ce qui l'amène à conclure que les Pyramimonadales seraient apparues avant 1500 Ma, et que le moment de divergence entre les algues vertes et les algues rouges serait proche de 2000 Ma. La date de 750 Ma, objet du litige, est bien loin ... L'auteur nous promet une Paléontologie du Précambrien à la lumière de la phylogénie moléculaire. Cet ouvrage très ciblé nous fait espérer une prochaine synthèse des nouvelles données sur l'évolution de la vie depuis les origines.
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Are the green algae (phylum Viridiplantae) two billion years old?
Carnets de Geologie, 2006Co-Authors: Bernard TeyssèdreAbstract:In his book, Life on a young planet, A.H. Knoll states that the first documented fossils of green algae date back 750 Ma. However, according to B. Teyssèdre's book, La vie invisible, they are much older. Using a method which combines paleontology and molecular phylogeny, this paper is an inquiry into the Precambrian fossils of some "acritarchs" and of a primitive clade of green algae, the Pyramimonadales. A paraphyletic group of unicellular green algae, named "Prasinophyceae", is represented at Thule (Greenland) ca. 1200 Ma by several morphotypes of the monophyletic Pyramimonadales, including Tasmanites and Pterospermella that are akin to algae still living today. These two, and others, probably had forerunners going back 1450 / 1550 Ma. Some acritarchs that may represent Pyramimonadales producing "phycomas" which split open for dehiscence were confusingly included in the polyphyletic pseudo-taxon "Leiosphaeridia" and are possibly already present at Chuanlinggou, China, ca. 1730 Ma. Many acritarchs that Timofeev obtained by acid maceration of Russian samples dated between 1800 and 2000 Ma were probably unicellular Chlorophyta which synthesized algaenans or other biopolymers resistant to acetolysis. Living Prasinophyceae are undoubtedly green algae (Viridiplantae). Thus, if Prasinophyceae fossils go back certainly to 1200 Ma, probably to 1500 Ma and possibly to 1730 Ma, then the ancestor of green algae (Chlorophyta and Streptophyta) probably separated from the ancestor of red algae (Rhodophyta) as early as 2000 Ma.
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Are the green algae (phylum Viridiplantae) two billion years old
Carnets de géologie (Notebooks on geology), 2006Co-Authors: Bernard TeyssèdreAbstract:In his book, Life on a young planet, A.H. KNOLL states that the first documented fossils of green algae date back 750 Ma. However, according to B. TEYSSEDRE's book, La vie invisible, they are much older. Using a method which combines paleontology and molecular phylogeny, this paper is an inquiry into the Precambrian fossils of some "acritarchs" and of a primitive clade of green algae, the Pyramimonadales. A paraphyletic group of unicellular green algae, named "Prasinophyceae", is represented at Thule (Greenland) ca. 1200 Ma by several morphotypes of the monophyletic Pyramimonadales, including Tasmanites and Pterospermella that are akin to algae still living today. These two, and others, probably had forerunners going back 1450 / 1550 Ma. Some acritarchs that may represent Pyramimonadales producing "phycomas" which split open for dehiscence were confusingly included in the polyphyletic pseudo-taxon "Leiosphaeridia" and are possibly already present at Chuanlinggou, China, ca. 1730 Ma. Many acritarchs that TIMOFEEV obtained by acid maceration of Russian samples dated between 1800 and 2000 Ma were probably unicellular Chlorophyta which synthesized algaenans or other biopolymers resistant to acetolysis. Living Prasinophyceae are undoubtedly green algae (Viridiplantae). Thus, if Prasinophyceae fossils go back certainly to 1200 Ma, probably to 1500 Ma and possibly to 1730 Ma, then the ancestor of green algae (Chlorophyta and Streptophyta) probably separated from the ancestor of red algae (Rhodophyta) as early as 2000 Ma.
Mohammad Azmal Hossain Bhuiyan - One of the best experts on this subject based on the ideXlab platform.
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Taxonomy and phylogeny of Pyramimonas vacuolata sp. nov. (Pyramimonadales, Chlorophyta)
Phycologia, 2015Co-Authors: Mohammad Azmal Hossain Bhuiyan, Stuart D. Sym, Daphne Georgina Faria, Takeo Horiguchi, Shoichiro SudaAbstract:Abstract: Pyramimonas vacuolata Suda, Horiguchi & Sym sp. nov. is described from Okinawa-jima Island, Japan. The species has been characterized using light and electron microscopy and its phylogenetic position inferred based on 18S rDNA and rbcL gene sequences relative to other species. Strains of P. vacuolata were isolated from coastal sand samples collected from two localities in Okinawa-jima. The cells are quadriflagellate but remarkably large for the genus, and the posterior half of the cell is vacuolated. The single parietal chloroplast is olive-green and contains two conspicuous pyrenoids lying on the same transverse plane, slightly anterior to the equatorial region of the cell. The pyrenoids are surrounded by numerous starch grains, and thylakoids randomly traverse the pyrenoid matrix. Two monolayered eyespots are present, situated on the same transverse plane as the pyrenoids. The alga possesses three types of body scales and four types of flagellar scales, inclusive of two types of hair scales. T...
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genetic diversity of pyramimonas from ryukyu archipelago japan chlorophyceae Pyramimonadales
Journal of Marine Science and Technology, 2013Co-Authors: Shoichiro Suda, Mohammad Azmal Hossain Bhuiyan, Daphne Georgina FariaAbstract:The genus Pyramimonas Schmarda was traditionally described on observations of its periplast and internal structure of different flagellar apparatus or eyespot orientations and currently comprises of ca. 60 species that are divided into six subgenera: Pyramimonas, Vestigifera, Trichocystis, Punctatae, Hexactis, and Macrura. In order to understand the genetic diversity and phylogenetic relationships of genus Pyramimonas members, we analyzed nuclear SSU rDNA molecular data from 41 strains isolated from different locations of the Ryukyu Archipelago. Phylogenetic analyses revealed that strains could be segregated into six clades, four of which represented existing subgenera: Pyramimonas, Vestigifera McFadden, Trichocystis McFadden, and Punctatae McFadden, and two undescribed subgenera. Most recovered subgenera were represented by established and confirmed species of Pyramimonas along with several potentially undescribed species with the exception of one undescribed subgenus. Many of the newly isolated strains were closely related with Pyramimonas aurea and P. olivacea, and were considered to belong to subgenus Punctatae. However, nuclear SSU rDNA phylogenetic trees clearly showed that they are genetically different and can be divided into two subgenera. Subgenus Punctatae comprised of Pyramimonas olivacea and related strains whilst, P. aurea and related strains belonged to an undescribed subgenus which is tentatively referred to as undescribed subgenus 1 which shared a sister-group relationship with subgenus Punctatae. The genetic similarity based on nuclear SSU rDNA ranged from 98.2% to 99.9% and 97.3% to 98.3% within and between subgenera, respectively. The present work shows high level of genetic diversity for the genus Pyramimonas from the Ryukyu Archipelago, Japan.
