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Hiroshi Kawai - One of the best experts on this subject based on the ideXlab platform.
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molecular phylogeny and biogeography of ecklonia spp Laminariales phaeophyceae in japan revealed taxonomic revision of e kurome and e stolonifera
Phycologia, 2020Co-Authors: Shingo Akita, Takeaki Hanyuda, Kazuki Hashimoto, Hiroshi KawaiAbstract:Species level taxonomy and genetic structures of local populations of Ecklonia species (Laminariales, Phaeophyceae) distributed in northeastern Asia were examined using multigene molecular phylogen...
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Genome-wide computational analysis of the secretome of brown algae (Phaeophyceae).
Marine Genomics, 2017Co-Authors: Makoto Terauchi, Takahiro Yamagishi, Takeaki Hanyuda, Hiroshi KawaiAbstract:Brown algae have evolved complex multicellularity in the heterokont lineage. They are phylogenetically distant to land plants, fungi and animals. Especially, the members of Laminariales (so-called kelps) have developed highly differentiated tissues. Extracellular matrix (ECM) plays pivotal roles in a number of essential processes in multicellular organisms, such as cell adhesion, cell and tissue differentiations, cell-to-cell communication, and responses to environmental stimuli. In these processes, a set of extracellular secreted proteins called the secretome operates remodeling of the physicochemical nature of ECM and signal transduction by interacting with cell surface proteins and signaling molecules. Characterization of the secretome is a critical step to clarify the contributions of ECM to the multicellularity of brown algae. However, the identity of the brown algal secretome has been poorly understood. In order to reveal the repertory of the brown algal secretome and its involvement in the evolution of Laminariales, we conducted a genome-wide analysis of the brown algal secretome utilizing the published complete genome data of Ectocarpus siliculosus and Saccharina japonica as well as newly obtained RNA-seq data of seven laminarialean species (Agarum clathratum, Alaria crassifolia, Aureophycus aleuticus, Costaria costata, Pseudochorda nagaii, Saccharina angustata and Undaria pinnatifida) largely covering the laminarialean families. We established the in silico pipeline to systematically and accurately detect the secretome by combining multiple prediction algorithms for the N-terminal signal peptide and transmembrane domain within the protein sequence. From 16,189 proteins of E. siliculosus and 18,733 proteins of S. japonica, 552 and 964 proteins respectively were predicted to be classified as the secretome. Conserved domain analysis showed that the domain repertory were very similar to each other, and that of the brown algal secretome was partially common with that of the secretome of other multicellular organisms (land plants, fungi and animals). In the laminarialean species, it was estimated that the gene abundance and the domain architecture of putative ECM remodeling-related proteins were altered compared with those of E. siliculosus, and that the alteration started from the basal group of Laminariales. These results suggested that brown algae have developed their own secretome, and its functions became more elaborated in the more derived members in Laminariales.
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Evolution and Biogeography of Laminarialean Kelps
Seaweed Phylogeography, 2016Co-Authors: Hiroshi Kawai, Takeaki Hanyuda, Shinya UwaiAbstract:This review covers the evolution of Laminariales and recent phylogeographic studies focusing on Chorda and Undaria. In Laminariales, the phylogenetic relationships between basal families (i.e., Akkesiphycaceae, Pseudochordaceae, and Chordaceae) with simple thallus structures, and derived families (i.e., Alariaceae, Laminariaceae, and Lessoniaceae) with large elaborate sporophytes, have remained unclear. Derived Laminariales have been suggested to consist of three major clades roughly corresponding to Alariaceae, Agaraceae (=Costariaceae), and Laminariaceae/Lessoniaceae. Recently, a novel species Aureophycus aleuticus, basal to all derived Laminariales, was found in the Bering Sea, and was shown to be basal to all derived Laminariales. Geographically, the majority of derived families in the Laminariales only occur in the Northern Hemisphere, and the Laminariales are therefore considered to have originated in the Northwestern Pacific and spread to the other regions including the Atlantic and the Southern Hemisphere. The limited distributional range of the basal families Akkesiphycaceae and Pseudochordaceae in northeastern Asia, and that of Aureophycaceae in the Bering Sea, supports the notion that the Laminariales originated in the Northwestern Pacific and evolved to giant taxa such as Macrocystis in the course of dispersal to the Northeastern Pacific, perhaps through the Aleutian Archipelago. Chordaceae has wide distributional ranges both in the Atlantic and Pacific oceans, but of the four clearly recognized species of Chorda, C. asiatica, C. rigida, and C. kikonaiensis are found only in the Northwestern Pacific, whereas C. filum is also found in the North Atlantic. In addition, the genetic diversity within C. asiatica is greater than that of C. filum, and it is suggested that Chorda also originated and diverged in the Pacific, then spread into the Atlantic. In the genus Undaria (Alariaceae), three species, U. pinnatifida, U. undarioides, and U. peterseniana have been traditionally recognized based on morphological characters, and U. crenata was recently described. Based on the genetic studies, U. crenata was considered to be conspecific with U. pinnatifida or U. peterseniana, although the three species were shown to be genetically rather close, at present we suggest retaining the species-level taxonomy. Based on genetic analyses, we discuss the likely geographic origin and dispersal pathways for nonindigenous populations of U. pinnatifida.
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Trigonelline and other betaines in species of Laminariales.
Natural product communications, 2012Co-Authors: Gerald Blunden, Louis D. Druehl, Michael D. Guiry, Kazuhiro Kogame, Hiroshi KawaiAbstract:A collection of Laminariales species was made with examples in each of the presently recognized families of the order. Extracts of each species were examined for betaines, using primarily 'H NMR spectroscopy for their identification. Glycinebetaine was detected in all species tested and would appear to be a consistent feature of the Laminariales. Gamma-Aminobutyric acid betaine was found in all species of Laminaria examined and in three of the five Saccharina species (family Laminariaceae), but was not detected in species of either other genera of the family or in those of other Laminariales families. Trigonelline was found in some Laminaria and Saccharina species, as well as in the north Pacific species Postelsia palmaeformis (Laminariaceae), Pseudochorda nagaii (Pseudochordaceae) and Akkesiphycus lubricus (Akkesiphycaceae).
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MORPHOLOGY AND MOLECULAR PHYLOGENY OF AUREOPHYCUS ALEUTICUS GEN. ET SP. NOV. (Laminariales, PHAEOPHYCEAE) FROM THE ALEUTIAN ISLANDS(1).
Journal of phycology, 2008Co-Authors: Hiroshi Kawai, Takeaki Hanyuda, Mandy R. Lindeberg, Sandra C. LindstromAbstract:A previously unknown species of kelp was collected on Kagamil Island, Aleutian Islands. The species can be easily distinguished from any known laminarialean alga: the erect sporophytic thallus is composed of a thin lanceolate blade attaining ∼2 m in height and ∼0.50 m in width, without midrib, and the edge of the blade at the transition zone is thickened to form a V-shape; the stipe is solid and flattened, slightly translucent, attaining ∼1 m in length; the holdfast is semidiscoidal and up to 0.15 m in diameter. Anatomically, the blade has the typical trumpet-shaped hyphae characteristic of the Chordaceae and derived foliose laminarialean species (i.e., Alariaceae/Laminariaceae/Lessoniaceae). No hair pits or mucilaginous structures were observed on the blade or stipe. No fertile sporophytes were collected, but abundant juvenile sporophytes were observed in the field. In the molecular phylogenetic analyses using chloroplast rbcL gene, nuclear ITS1-5.8S-ITS2 rDNA, and mitochondria nad6 DNA sequences, the new species (Aureophycus aleuticus gen. et sp. nov.) showed a closer relationship with Alariaceae of conventional taxonomy, or the "Group 1" clade of Lane et al. (2006) including Alaria and related taxa than with other groups, although the species was not clearly included in the group. Aureophycus may be a key species in elucidating the evolution of the Alariaceae within the Laminariales. Because of the lack of information on reproductive organs and insufficient resolution of the molecular analyses, we refrain from assigning the new species to a family, but we place the new species in a new genus in the Laminariales.
Dagmar B Stengel - One of the best experts on this subject based on the ideXlab platform.
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Intra-thallus differentiation of fatty acid and pigment profiles in some temperate Fucales and Laminariales.
Journal of Phycology, 2015Co-Authors: Matthias Schmid, Dagmar B StengelAbstract:Intra-thallus variation in fatty acid and pigment contents and profiles was investigated in five species of Laminariales (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, and Saccorhiza polyschides), and three Fucales (Ascophyllum nodosum, Fucus serratus, and Himanthalia elongata). Significant variation occurred across all species and compounds examined. Total fatty acids were generally higher in the fronds, with highest levels and largest variability observed in A. nodosum (1.5% of dry weight (DW) in the base, 6.3% of DW in frond tips). Percentages of the omega-3 fatty acids 18:4 n-3 and 20:5 n-3 were generally higher in more distal parts, while 20:4 n-6 exhibited a contrasting pattern, with higher levels in basal structures and holdfasts. Trends for pigments were similar to those for fatty acids in Laminariales. In the Fucales, highest levels were detected in the mid-fronds, with lower concentrations in meristematic areas. Highest levels and greatest variability in pigments (e.g., chl a) was observed in F. serratus (1.07 mg · g−1 DW in the base, 3.04 mg · g−1 DW in the mid frond). Intra-thallus variability was attributed to physiological functions of the respective thallus sections, e.g., photosynthetic activity, meristematic tissue, and to variations in physical attributes of the structures investigated. Regarding potential commercial nutritional applications, fronds appeared to represent most suitable source materials, due to higher levels of pigments, polyunsaturated fatty acids, and more preferable omega-3/omega-6 ratios.
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Intra‐thallus differentiation of fatty acid and pigment profiles in some temperate Fucales and Laminariales
Journal of phycology, 2015Co-Authors: Matthias Schmid, Dagmar B StengelAbstract:Intra-thallus variation in fatty acid and pigment contents and profiles was investigated in five species of Laminariales (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, and Saccorhiza polyschides), and three Fucales (Ascophyllum nodosum, Fucus serratus, and Himanthalia elongata). Significant variation occurred across all species and compounds examined. Total fatty acids were generally higher in the fronds, with highest levels and largest variability observed in A. nodosum (1.5% of dry weight (DW) in the base, 6.3% of DW in frond tips). Percentages of the omega-3 fatty acids 18:4 n-3 and 20:5 n-3 were generally higher in more distal parts, while 20:4 n-6 exhibited a contrasting pattern, with higher levels in basal structures and holdfasts. Trends for pigments were similar to those for fatty acids in Laminariales. In the Fucales, highest levels were detected in the mid-fronds, with lower concentrations in meristematic areas. Highest levels and greatest variability in pigments (e.g., chl a) was observed in F. serratus (1.07 mg · g(-1) DW in the base, 3.04 mg · g(-1) DW in the mid frond). Intra-thallus variability was attributed to physiological functions of the respective thallus sections, e.g., photosynthetic activity, meristematic tissue, and to variations in physical attributes of the structures investigated. Regarding potential commercial nutritional applications, fronds appeared to represent most suitable source materials, due to higher levels of pigments, polyunsaturated fatty acids, and more preferable omega-3/omega-6 ratios.
Louis D. Druehl - One of the best experts on this subject based on the ideXlab platform.
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Trigonelline and other betaines in species of Laminariales.
Natural product communications, 2012Co-Authors: Gerald Blunden, Louis D. Druehl, Michael D. Guiry, Kazuhiro Kogame, Hiroshi KawaiAbstract:A collection of Laminariales species was made with examples in each of the presently recognized families of the order. Extracts of each species were examined for betaines, using primarily 'H NMR spectroscopy for their identification. Glycinebetaine was detected in all species tested and would appear to be a consistent feature of the Laminariales. Gamma-Aminobutyric acid betaine was found in all species of Laminaria examined and in three of the five Saccharina species (family Laminariaceae), but was not detected in species of either other genera of the family or in those of other Laminariales families. Trigonelline was found in some Laminaria and Saccharina species, as well as in the north Pacific species Postelsia palmaeformis (Laminariaceae), Pseudochorda nagaii (Pseudochordaceae) and Akkesiphycus lubricus (Akkesiphycaceae).
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A multi-gene molecular investigation of the kelp (Laminariales, Phaeophyceae) supports substantial taxonomic re-organization
Journal of Phycology, 2006Co-Authors: Christopher E. Lane, Louis D. Druehl, Charlene Mayes, Gary W. SaundersAbstract:Every year numerous ecological, biochemical, and physiological studies are performed using members of the order Laminariales. Despite the fact that kelp are some of the most intensely studied macroalgae in the world, there is significant debate over the classification within and among the three ‘‘derived’’ families, the Alariaceae, Laminariaceae, and Lessoniaceae (ALL). Molecular phylogenies published for the ALL families have generated hypotheses strongly at odds with the current morphological taxonomy; however, conflicting phylogenetic hypotheses and consistently low levels of support realized in all of these studies have resulted in conservative approaches to taxonomic revisions. In order to resolve relationships within this group we have sequenced over 6000bp from regions in the nuclear, chloroplast, and mitochondrial genomes and included 42 taxa in Bayesian, neighbor-joining, and parsimony analyses. The result is the first comprehensive and well-supported molecular phylogeny for the ALL complex of the Laminariales. We maintain the three recognized families (Alariaceae, Laminariaceae, and Lessoniaceae), but with vastly different compositions, as well as propose the Costariaceae fam. nov. for Agarum, Costaria, Dictyoneurum, and Thalassiophyllum, the only genera in the Laminariales with flattened, occasionally terete, stipes and either a perforate or reticulate blade. In addition, our data strongly support a split of the genus Laminaria. We resurrect the genus Saccharina Stackhouse for the Laminaria clade that does not contain L. digitata (Hudson) J.V. Lamouroux, the type of the genus. Key index words: Costariaceae; Laminariales; long branch attraction; nested analyses; phylogenetics; Saccharina
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Molecular and morphological phylogenies of kelp and associated brown algae
Plant Systematics and Evolution, 1997Co-Authors: Louis D. Druehl, C. Mayes, I. H. Tan, G. W. SaundersAbstract:Morphological and molecular phylogenies of kelp (Laminariales, Phaeophyceae), the world’s largest protists, are generally at odds. This chapter discusses the current state of knowledge for relationships of the Laminariales relative to other orders of brown algae (Phaeophyceae) and among the families of kelp, in particular, the Alariaceae, Laminariaceae and Lessoniaceae. Phylogenetic relationships among fourteen kelp species, representing these three families were inferred from newly obtained and previously published (3’18S — ITS1 — 5.8S) rDNA sequences.
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A RIBOSOMAL DNA PHYLOGENY SUPPORTS THE CLOSE EVOLUTIONARY RELATIONSHIPS AMONG THE SPOROCHNALES, DESMARESTIALES, AND Laminariales (PHAEOPHYCEAE)1
Journal of Phycology, 1996Co-Authors: Louis D. DruehlAbstract:We report six complete 18S ribosomal DNA (rDNA) sequences representing five brown algal orders: Sporochnus comosus C. A. Agardh (Sporochnales), Chorda tomentosa Lyngbye (Chordaceae, Laminariales), Saccorhiza polyschides (Lightfoot) Batters (Phyllariaceae, Laminariales), Desmarestia ligulata (Lightfoot) Lamouroux (Desmarestiales), Ectocarpus siliculosus (Dillwyn) Lyngbye (Ectocarpales), and Scytosiphon lomentaria (Lyngbye) J. G. Agardh (Scytosiphonales). These sequences were compared with published laminarialean (Alaria marginata Postel et Ruprecht [Alariaceae] and Macrocystis integrifolia Bory [Lessoniaceae]) and fucalean (Fucus gardneri Silva) rDNA sequences for phylogeny inference using both the distance-matrix and parsimony methods. The inferred 18S phylogenies clustered Sporochnus, Desmarestia, Chorda, Saccorhiza, Alaria, and Macrocystis in an assemblage. This Sporochnales–Desmarestiales–Laminariales (S-D-L) complex was consistently separated from the Ectocarpales, Scytosiphonales, and Fucales by bootstrap analyses. The inferred phylogenies are consistent with several possible evolutionary processes leading to this S-D-L complex. Members in this assemblage lack eyespots in their sperm, and their sperm have the atypical brown algal flagellation: shorter anterior and longer posterior flagella. In addition, they are oogamous with a heteromorphic alternation of generations between a microscopic gametophyte and a macroscopic sporophyte. Members of the S-D-L complex can be separated into different phylogenetic lines based on the presence/absence of eyespots in their meiospores. Our findings support the contention that the Sporochnales, Desmarestiales, and Laminariales are closely related. In addition, our rDNA tree suggests that the Laminariales is paraphyletic.
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Revision of the kelp family Alariaceae and the taxonomic affinities of Lessoniopsis Reinke (Laminariales, Phaeophyta)
Fourteenth International Seaweed Symposium, 1993Co-Authors: Gary W. Saunders, Louis D. DruehlAbstract:The morphologically diverse members of the Laminariales are separated into three families, the Alariaceae,Laminariaceae and Lessoniaceae, on the basis of developmental features exhibited at the stipeblade transition zone. We have investigated the relationships of lessoniacean taxa with those of alariacean and laminariacean affinity. This was done by completing phylogenetic analyses of 3′ small-subunit (SSU) rRNA gene (113 bp), first internal transcribed spacer (ITS1), 5.8S rRNA gene and second internal transcribed spacer (ITS2)(12 bp) sequence data from a variety of taxa. In summary, the Alariaceae and Lessoniaceae are polyphyletic. We present a restricted view of the Alariaceae, including only Alaria and Pterygophora of the genera usually placed in this family, and transfer the monotypic genus Lessoniopsis to this group. Current theories of kelp evolution and biogeography must be reconsidered in view of our data.
Matthias Schmid - One of the best experts on this subject based on the ideXlab platform.
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Intra-thallus differentiation of fatty acid and pigment profiles in some temperate Fucales and Laminariales.
Journal of Phycology, 2015Co-Authors: Matthias Schmid, Dagmar B StengelAbstract:Intra-thallus variation in fatty acid and pigment contents and profiles was investigated in five species of Laminariales (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, and Saccorhiza polyschides), and three Fucales (Ascophyllum nodosum, Fucus serratus, and Himanthalia elongata). Significant variation occurred across all species and compounds examined. Total fatty acids were generally higher in the fronds, with highest levels and largest variability observed in A. nodosum (1.5% of dry weight (DW) in the base, 6.3% of DW in frond tips). Percentages of the omega-3 fatty acids 18:4 n-3 and 20:5 n-3 were generally higher in more distal parts, while 20:4 n-6 exhibited a contrasting pattern, with higher levels in basal structures and holdfasts. Trends for pigments were similar to those for fatty acids in Laminariales. In the Fucales, highest levels were detected in the mid-fronds, with lower concentrations in meristematic areas. Highest levels and greatest variability in pigments (e.g., chl a) was observed in F. serratus (1.07 mg · g−1 DW in the base, 3.04 mg · g−1 DW in the mid frond). Intra-thallus variability was attributed to physiological functions of the respective thallus sections, e.g., photosynthetic activity, meristematic tissue, and to variations in physical attributes of the structures investigated. Regarding potential commercial nutritional applications, fronds appeared to represent most suitable source materials, due to higher levels of pigments, polyunsaturated fatty acids, and more preferable omega-3/omega-6 ratios.
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Intra‐thallus differentiation of fatty acid and pigment profiles in some temperate Fucales and Laminariales
Journal of phycology, 2015Co-Authors: Matthias Schmid, Dagmar B StengelAbstract:Intra-thallus variation in fatty acid and pigment contents and profiles was investigated in five species of Laminariales (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, and Saccorhiza polyschides), and three Fucales (Ascophyllum nodosum, Fucus serratus, and Himanthalia elongata). Significant variation occurred across all species and compounds examined. Total fatty acids were generally higher in the fronds, with highest levels and largest variability observed in A. nodosum (1.5% of dry weight (DW) in the base, 6.3% of DW in frond tips). Percentages of the omega-3 fatty acids 18:4 n-3 and 20:5 n-3 were generally higher in more distal parts, while 20:4 n-6 exhibited a contrasting pattern, with higher levels in basal structures and holdfasts. Trends for pigments were similar to those for fatty acids in Laminariales. In the Fucales, highest levels were detected in the mid-fronds, with lower concentrations in meristematic areas. Highest levels and greatest variability in pigments (e.g., chl a) was observed in F. serratus (1.07 mg · g(-1) DW in the base, 3.04 mg · g(-1) DW in the mid frond). Intra-thallus variability was attributed to physiological functions of the respective thallus sections, e.g., photosynthetic activity, meristematic tissue, and to variations in physical attributes of the structures investigated. Regarding potential commercial nutritional applications, fronds appeared to represent most suitable source materials, due to higher levels of pigments, polyunsaturated fatty acids, and more preferable omega-3/omega-6 ratios.
Akira F. Peters - One of the best experts on this subject based on the ideXlab platform.
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Phaeoviral Infections Are Present in Macrocystis, Ecklonia and Undaria (Laminariales) and Are Influenced by Wave Exposure in Ectocarpales.
Viruses, 2018Co-Authors: Dean A Mckeown, Akira F. Peters, Kim Stevens, Murray T. Brown, Joanna L. Schroeder, Claudio A. Sáez, Jihae Park, Mark D. Rothman, John J. Bolton, Declan C. SchroederAbstract:Two sister orders of the brown macroalgae (class Phaeophyceae), the morphologically complex Laminariales (commonly referred to as kelp) and the morphologically simple Ectocarpales are natural hosts for the dsDNA phaeoviruses (family Phycodnaviridae) that persist as proviruses in the genomes of their hosts. We have previously shown that the major capsid protein (MCP) and DNA polymerase concatenated gene phylogeny splits phaeoviruses into two subgroups, A and B (both infecting Ectocarpales), while MCP-based phylogeny suggests that the kelp phaeoviruses form a distinct third subgroup C. Here we used MCP to better understand the host range of phaeoviruses by screening a further 96 and 909 samples representing 11 and 3 species of kelp and Ectocarpales, respectively. Sporophyte kelp samples were collected from their various natural coastal habitats spanning five continents: Africa, Asia, Australia, Europe, and South America. Our phylogenetic analyses showed that while most of the kelp phaeoviruses, including one from Macrocystispyrifera, belonged to the previously designated subgroup C, new lineages of Phaeovirus in 3 kelp species, Ecklonia maxima, Ecklonia radiata, Undaria pinnatifida, grouped instead with subgroup A. In addition, we observed a prevalence of 26% and 63% in kelp and Ectocarpales, respectively. Although not common, multiple phaeoviral infections per individual were observed, with the Ectocarpales having both intra- and inter-subgroup phaeoviral infections. Only intra-subgroup phaeoviral infections were observed in kelp. Furthermore, prevalence of phaeoviral infections within the Ectocarpales is also linked to their exposure to waves. We conclude that phaeoviral infection is a widely occurring phenomenon in both lineages, and that phaeoviruses have diversified with their hosts at least since the divergence of the Laminariales and Ectocarpales.
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Phaeoviruses discovered in kelp (Laminariales)
The ISME journal, 2017Co-Authors: Dean A Mckeown, Akira F. Peters, Kim Stevens, Peter Bond, Glenn M. Harper, Colin Brownlee, Murray T. Brown, Declan C. SchroederAbstract:Phaeoviruses are latent double-stranded DNA viruses that insert their genomes into those of their brown algal (Phaeophyceae) hosts. So far these viruses are known only from members of the Ectocarpales, which are small and short-lived macroalgae. Here we report molecular and morphological evidence for a new Phaeovirus cluster, referred to as sub-group C, infecting kelps (Laminariales) of the genera Laminaria and Saccharina, which are ecologically and commercially important seaweeds. Epifluorescence and TEM observations indicate that the Laminaria digitata Virus (LdigV), the type species of sub-group C, targets the host nucleus for its genome replication, followed by gradual degradation of the chloroplast and assembly of virions in the cytoplasm of both vegetative and reproductive cells. This study is the first to describe phaeoviruses in kelp. In the field, these viruses infected two thirds of their host populations; however, their biological impact remains unknown.
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Primer information and PCR conditions for the sex-specific marker tests carried out on the three Laminariales species L. digitata, M. pyrifera and U. pinnatifida.
2015Co-Authors: Agnieszka P. Lipinska, Sophia Ahmed, Akira F. Peters, Sylvain Faugeron, Mark J. Cock, Susana M. CoelhoAbstract:*D–denaturation time, A–annealing time, E–elongation time, TA- annealing temperature.**NA–no amplificationPrimer information and PCR conditions for the sex-specific marker tests carried out on the three Laminariales species L. digitata, M. pyrifera and U. pinnatifida.
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Ribosomal DNA sequences support taxonomic separation of the two species of Chorda: reinstatement of Halosiphon tomentosus (Lyngbye) Jaasund (Phaeophyceae, Laminariales)
European Journal of Phycology, 1998Co-Authors: Akira F. PetersAbstract:The brown algal family Chordaceae contains the single genus Chorda with two terete unbranched species, C. filum and C. tomentosa. They share a similar superficial morphology, but differences in anatomy and reproductive characters have made assignment to a single genus controversial. Comparison of DNA sequences of variable parts of the small subunit of the nuclear ribosomal cistron, and of relatively conserved areas of both internal transcribed spacers, of several taxa of the Sporochnales–Desmarestiales–Laminariales complex revealed that the two species of Chorda are not closely related and do not form a clade. This is taken as support for recognition of Halosiphon tomentosus (Lyngbye) Jaasund, although it was originally based on the erroneous observation of a Streblonema-like gametophyte in the life history of H. tomentosus.
