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Frithjof C Kupper - One of the best experts on this subject based on the ideXlab platform.
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emission of volatile halogenated compounds speciation and localization of bromine and iodine in the brown algal genome model Ectocarpus siliculosus
Journal of Biological Inorganic Chemistry, 2018Co-Authors: Frithjof C Kupper, Lucy J Carpenter, Chiaki Toyama, Eric P Miller, Stephen J Andrews, Claire Hughes, Wolfram Meyerklaucke, Yasuyuki Muramatsu, Martin C FeitersAbstract:This study explores key features of bromine and iodine metabolism in the filamentous brown alga and genomics model Ectocarpus siliculosus. Both elements are accumulated in Ectocarpus, albeit at much lower concentration factors (2-3 orders of magnitude for iodine, and < 1 order of magnitude for bromine) than e.g. in the kelp Laminaria digitata. Iodide competitively reduces the accumulation of bromide. Both iodide and bromide are accumulated in the cell wall (apoplast) of Ectocarpus, with minor amounts of bromine also detectable in the cytosol. Ectocarpus emits a range of volatile halogenated compounds, the most prominent of which by far is methyl iodide. Interestingly, biosynthesis of this compound cannot be accounted for by vanadium haloperoxidase since the latter have not been found to catalyze direct halogenation of an unactivated methyl group or hydrocarbon so a methyl halide transferase-type production mechanism is proposed.
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infection of the brown alga Ectocarpus siliculosus by the oomycete eurychasma dicksonii induces oxidative stress and halogen metabolism
Plant Cell and Environment, 2016Co-Authors: Frithjof C Kupper, Claire M. M. Gachon, Pieter Van West, Laura J Grenvillebriggs, Martina Strittmatter, Lisa BreithutAbstract:Pathogens are increasingly being recognized as key evolutionary and ecological drivers in marine ecosystems. Defence mechanisms of seaweeds, however, have mostly been investigated by mimicking infection using elicitors. We have established an experimental pathosystem between the genome brown model seaweed Ectocarpus siliculosus and the oomycete Eurychasma dicksonii as a powerful new tool to investigate algal responses to infection. Using proteomics, we identified 21 algal proteins differentially accumulated in response to Eu. dicksonii infection. These include classical algal stress response proteins such as a manganese superoxide dismutase, heat shock proteins 70 and a vanadium bromoperoxidase. Transcriptional profiling by qPCR confirmed the induction of the latter during infection. The accumulation of hydrogen peroxide was observed at different infection stages via histochemical staining. Inhibitor studies confirmed that the main source of hydrogen peroxide is superoxide converted by superoxide dismutase. Our data give an unprecedented global overview of brown algal responses to pathogen infection, and highlight the importance of oxidative stress and halogen metabolism in these interactions. This suggests overlapping defence pathways with herbivores and abiotic stresses. We also identify previously unreported actors, in particular a Rad23 and a plastid-lipid-associated protein, providing novel insights into the infection and defence processes in brown algae.
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surface bound iron a metal ion buffer in the marine brown alga Ectocarpus siliculosus
Journal of Experimental Botany, 2014Co-Authors: Eric P Miller, Frithjof C Kupper, Wolfram Meyerklaucke, Lars H. Böttger, Berthold F. Matzanke, Aruna J Weerasinghe, Alvin L Crumbliss, Carl J. CarranoAbstract:Although the iron uptake and storage mechanisms of terrestrial/higher plants have been well studied, the corresponding systems in marine algae have received far less attention. Studies have shown that while some species of unicellular algae utilize unique mechanisms of iron uptake, many acquire iron through the same general mechanisms as higher plants. In contrast, the iron acquisition strategies of the multicellular macroalgae remain largely unknown. This is especially surprising since many of these organisms represent important ecological and evolutionary niches in the coastal marine environment. It has been well established in both laboratory and environmentally derived samples, that a large amount of iron can be ‘non-specifically’ adsorbed to the surface of marine algae. While this phenomenon is widely recognized and has prompted the development of experimental protocols to eliminate its contribution to iron uptake studies, its potential biological significance as a concentrated iron source for marine algae is only now being recognized. This study used an interdisciplinary array of techniques to explore the nature of the extensive and powerful iron binding on the surface of both laboratory and environmental samples of the marine brown alga Ectocarpus siliculosus and shows that some of this surface-bound iron is eventually internalized. It is proposed that the surfacebinding properties of E. siliculosus allow it to function as a quasibiological metal ion ‘buffer’, allowing iron uptake under the widely varying external iron concentrations found in coastal marine environments.
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a molecular insight into algal oomycete warfare cdna analysis of Ectocarpus siliculosus infected with the basal oomycete eurychasma dicksonii
PLOS ONE, 2011Co-Authors: Laura J Grenvillebriggs, Lieven Sterck, Frithjof C Kupper, Claire M. M. Gachon, Martina Strittmatter, Pieter Van WestAbstract:Brown algae are the predominant primary producers in coastal habitats, and like land plants are subject to disease and parasitism. Eurychasma dicksonii is an abundant, and probably cosmopolitan, obligate biotrophic oomycete pathogen of marine brown algae. Oomycetes (or water moulds) are pathogenic or saprophytic non-photosynthetic Stramenopiles, mostly known for causing devastating agricultural and aquacultural diseases. Whilst molecular knowledge is restricted to crop pathogens, pathogenic oomycetes actually infect hosts from most eukaryotic lineages. Molecular evidence indicates that Eu. dicksonii belongs to the most early-branching oomycete clade known so far. Therefore Eu. dicksonii is of considerable interest due to its presumed environmental impact and phylogenetic position. Here we report the first large scale functional molecular data acquired on the most basal oomycete to date. 9873 unigenes, totalling over 3.5Mb of sequence data, were produced from Sanger-sequenced and pyrosequenced EST libraries of infected Ectocarpus siliculosus. 6787 unigenes (70%) were of algal origin, and 3086 (30%) oomycete origin. 57% of Eu. dicksonii sequences had no similarity to published sequence data, indicating that this dataset is largely unique. We were unable to positively identify sequences belonging to the RXLR and CRN groups of oomycete effectors identified in higher oomycetes, however we uncovered other unique pathogenicity factors. These included putative algal cell wall degrading enzymes, cell surface proteins, and cyclophilin-like proteins. A first look at the host response to infection has also revealed movement of the host nucleus to the site of infection as well as expression of genes responsible for strengthening the cell wall, and secretion of proteins such as protease inhibitors. We also found evidence of transcriptional reprogramming of E. siliculosus transposable elements and of a viral gene inserted in the host genome.
Dieter G. Müller - One of the best experts on this subject based on the ideXlab platform.
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ultrastructural analysis of flagellar development in plurilocular sporangia of Ectocarpus siliculosus phaeophyceae
Protoplasma, 2013Co-Authors: Chikako Nagasato, Dieter G. Müller, Toshiaki Ito, Taizo MotomuraAbstract:Flagellar development in the plurilocular zoidangia of sporophytes of the brown alga Ectocarpus siliculosus was analyzed in detail using transmission electron microscopy and electron tomography. A series of cell divisions in the plurilocular zoidangia produced the spore-mother cells. In these cells, the centrioles differentiated into flagellar basal bodies with basal plates at their distal ends and attached to the plasma membrane. The plasma membrane formed a depression (flagellar pocket) into where the flagella elongated and in which variously sized vesicles and cytoplasmic fragments accumulated. The anterior and posterior flagella started elongating simultaneously, and the vesicles and cytoplasmic fragments in the flagellar pocket fused to the flagellar membranes. The two flagella (anterior and posterior) could be clearly distinguished from each other at the initial stage of their development by differences in length, diameter and the appendage flagellar rootlets. Flagella continued to elongate in the flagellar pocket and maintained their mutually parallel arrangement as the flagellar pocket gradually changed position. In mature zoids, the basal part of the posterior flagellum (paraflagellar body) characteristically became swollen and faced the eyespot region. Electron dense materials accumulated between the axoneme and the flagellar membrane, and crystallized materials could also be observed in the swollen region. Before liberation of the zoospores from the plurilocular zoidangia, mastigoneme attachment was restricted to the distal region of the anterior flagellum. Structures just below the flagellar membrane that connected to the mastigonemes were clearly visible by electron tomography.
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Female gamete membrane glycoproteins potentially involved in gamete recognition in Ectocarpus siliculosus (Phaeophyceae)
Plant Science, 2003Co-Authors: Christine E. Schmid, Nora Schroer, Dieter G. MüllerAbstract:Abstract In the plasma membrane-enriched fraction of female gametes of Ectocarpus siliculosus (Phaeophyceae) four sex-specific glycoproteins (P2–3, P5, P16) exposing N- acetylglucosamine (GlcNAc) residues were detected in vitro. In immunoblots these proteins were labelled with the GlcNAc complementary lectin wheat germ agglutinin (WGA) conjugated to digoxigenin. P2 also cross-reacted with the mannose-specific Galanthus nivalis agglutinin (GNA). Previously, a key and lock mechanism of gamete recognition was demonstrated in vivo: fertilization can be selectively inhibited by a WGA pretreatment of female gametes, or by GlcNAc pretreated male gametes. Lectins with different carbohydrate requirements such as GNA do not affect fertilization in vivo. Thus, the remaining glycoproteins P3, P5 and P16 seem to be involved in cell-cell recognition during fertilization, and possibly one of them functions as the male receptor in the plasma membrane of female gametes. Membrane proteins of both gamete types showed higher differences than cytosolic proteins or proteins extracted from whole cells when examined by high resolution two-dimensional gel electrophoresis.
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Detection of virus DNA in Ectocarpus siliculosus and E. fasciculatus (Phaeophyceae) from various geographic areas
European Journal of Phycology, 1996Co-Authors: M.r. Sengco, M. Bräutigam, M. Kapp, Dieter G. MüllerAbstract:The filamentous marine brown algae Ectocarpus siliculosus and E. fasciculatus are frequently infected by DNA viruses. We used polymerase chain reaction amplification (PCR) of a virus-specific nucleotide sequence to detect the presence of viral DNA in extracts of Ectocarpus plants, and applied this technique to a collection of 97 unialgal Ectocarpus cultures from coasts of all oceans and continents. We found that 42 isolates contained viral DNA. Among these were four sporophytes, which produced gametophytes free of virus DNA. This observation supports previous studies showing that the viral genome segregates like a Mendelian trait during meiosis. The pandemy and epidemiology of the host-virus relationship in Ectocarpus is discussed.
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CROSSING EXPERIMENTS, LIPID COMPOSITION, AND THE SPECIES CONCEPT IN Ectocarpus siliculosus AND E. FASCICULATUS (PHAEOPHYCEAE, ECTOCARPALES)1
Journal of Phycology, 1995Co-Authors: Dieter G. Müller, Waldemar EichenbergerAbstract:Sporophytes of Ectocarpus siliculosus (Dillwyn) Lyngbye and E. fasciculatus Harvey were collected in the vicinity of Roscoff Brittany, France. Gametophytes derived from meiospores were used for intra- and interspecific crosses. Intraspecific gamete combinations gave viable zygotes, which developed into fertile sporophytes. Interspecific crosses were unsuccessful. Gamete fusions did not occur between female gametes of E. fasciculatus and male gametes of E. siliculosus. Hybrid zygotes were formed in the reciprocal combination but died soon after germination. We conclude that the two species of Ectocarpus at Roscoff represent distinct taxonomic entities, which are separated by pre- and postzygotic compatibility barriers. These biological findings are confirmed by the differential occurrence of the chemotaxonomic marker betaine-lipid diacetylglycerylhydroxymethyltrimethyl-β-alanine, which is present in our cultures of E. fasciculatus but absent in E. siliculosus.
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Coat Protein of the Ectocarpus siliculosus Virus
Virology, 1995Co-Authors: Michael Klein, Rolf Knippers, Stefan T. J. Lanka, Dieter G. MüllerAbstract:Abstract Ectocarpus siliculosus virus, EsV, multiplies in sporangia and gametangia of the marine brown alga Ectocarpus siliculosus.We describe an improved method for the isolation of morphologically intact and infectious virus from diseased plants. We show that treatment of virus particles with high concentrations of CsCl results in a substantial loss of structural proteins. One of the proteins which resists CsCl treatment is glycoprotein-1, the largest of the three viral glycoproteins. We have isolated an EsV genomic fragment with an open reading frame encoding glycoprotein-1. The predicted amino acid sequence is rich in hydrophilic amino acids, but contains hydrophobic regions close to the amino and carboxy termini. A discrepancy between the molecular weight predicted from the coding region and the molecular weight determined by gel electrophoresis suggests that proteolytic processing is required for the maturation of the protein.
Benedicte Charrier - One of the best experts on this subject based on the ideXlab platform.
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Laser capture microdissection in Ectocarpus siliculosus: the pathway to cell-specific transcriptomics in brown algae
Frontiers in Plant Science, 2015Co-Authors: Denis Saint-marcoux, Bernard Billoud, Jane A. Langdale, Benedicte CharrierAbstract:Laser capture microdissection (LCM) facilitates the isolation of individual cells from tissue sections, and when combined with RNA amplification techniques, it is an extremely powerful tool for examining genome-wide expression profiles in specific cell-types. LCM has been widely used to address various biological questions in both animal and plant systems, however, no attempt has been made so far to transfer LCM technology to macroalgae. Macroalgae are a collection of widespread eukaryotes living in fresh and marine water. In line with the collective effort to promote molecular investigations of macroalgal biology, here we demonstrate the feasibility of using LCM and cell-specific transcriptomics to study development of the brown alga Ectocarpus siliculosus. We describe a workflow comprising cultivation and fixation of algae on glass slides, laser microdissection, and RNA amplification. To illustrate the effectiveness of the procedure, we show qPCR data and metrics obtained from cell-specific transcriptomes generated from both upright and prostrate filaments of Ectocarpus.
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Edinburgh, UK Reviewed by:
2015Co-Authors: Denis Saint-marcoux, Bernard Billoud, Benedicte Charrier, Jane A. Langdale, Olivier De Clerck, Samuel Elias WuestAbstract:Laser capture microdissection in Ectocarpus siliculosus
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Computational prediction and experimental validation of microRNAs in the brown alga Ectocarpus siliculosus.
Nucleic Acids Research, 2014Co-Authors: Bernard Billoud, Aude Le Bail, Zofia Nehr, Benedicte CharrierAbstract:We used an in silico approach to predict microRNAs (miRNAs) genome-wide in the brown alga Ectocarpus siliculosus. As brown algae are phylogenetically distant from both animals and land plants, our approach relied on features shared by all known organisms, excluding sequence conservation, genome localization and pattern of base-pairing with the target. We predicted between 500 and 1500 miRNAs candidates, depending on the values of the energetic parameters used to filter the potential precursors. Using quantitative polymerase chain reaction assays, we confirmed the existence of 22 miRNAs among 72 candidates tested, and of 8 predicted precursors. In addition, we compared the expression of miRNAs and their precursors in two life cycle states (sporophyte, gametophyte) and under salt stress. Several miRNA precursors, Argonaute and DICER messenger RNAs were differentially expressed in these conditions. Finally, we analyzed the gene organization and the target functions of the predicted candidates. This showed that E. siliculosus miRNA genes are, like plant miRNA genes, rarely clustered and, like animal miRNA genes, often located in introns. Among the predicted targets, several widely conserved functional domains are significantly overrepresented, like kinesin, nucleotide-binding/APAF-1, R proteins and CED-4 (NB-ARC) and tetratricopeptide repeats. The combination of computational and experimental approaches thus emphasizes the originality of molecular and cellular processes in brown algae.
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Culture methods and mutant generation in the filamentous brown algae Ectocarpus siliculosus.
Methods in Molecular Biology, 2012Co-Authors: Aude Le Bail, Benedicte CharrierAbstract:Ectocarpus siliculosus is a small filamentous alga that has recently emerged as the new model for fundamental research on brown algae. Here, we describe the basic culture protocols for propagating and collecting E. siliculosus material that can then be used in all types of molecular biology, biochemistry and cell biology techniques. In addition, procedures for carrying out genetic experiments (generation of mutants and genetic segregation analyses) on E. siliculosus are described.
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space time decoupling in the branching process in the mutant etoile of the filamentous brown alga Ectocarpus siliculosus
Plant Signaling & Behavior, 2011Co-Authors: Zofia Nehr, Bernard Billoud, Aude Le Bail, Benedicte CharrierAbstract:Ectocarpus siliculosus is being developed as a model organism for brown algal genetics and genomics. Brown algae are phylogenetically distant from the other multicellular phyla (green lineage, red algae, fungi and metazoan) and therefore might offer the opportunity to study novel and alternative developmental processes that lead to the establishment of multicellularity. E. siliculosus develops as uniseriate filaments, thereby displaying one of the simplest architectures among multicellular organisms. The young sporophyte grows as a primary filament and then branching occurs, preferentially at the center of the filament. We recently described the first morphogenetic mutant etoile (etl) in a brown alga, produced by UVB mutagenesis in E. siliculosus. We showed that a single recessive mutation was responsible for a defect in both cell differentiation and the very early branching pattern (first and second branch emergences). Here, we supplement this study by reporting the branching defects observed subsequently, i.e. for the later stages corresponding to the emergence of up to the first six secondary filaments, and we show that the branching process is composed of at least two distinct components: time and position.
Wilhelm Boland - One of the best experts on this subject based on the ideXlab platform.
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The genome of the brown alga Ectocarpus siliculosus contains a series of viral DNA pieces, suggesting an ancient association with large dsDNA viruses
BMC evolutionary biology, 2008Co-Authors: Nicolas Delaroque, Wilhelm BolandAbstract:Ectocarpus siliculosus virus-1 (EsV-1) is a lysogenic dsDNA virus belonging to the super family of nucleocytoplasmic large DNA viruses (NCLDV) that infect Ectocarpus siliculosus, a marine filamentous brown alga. Previous studies indicated that the viral genome is integrated into the host DNA. In order to find the integration sites of the viral genome, a genomic library from EsV-1-infected algae was screened using labelled EsV-1 DNA. Several fragments were isolated and some of them were sequenced and analyzed in detail. Analysis revealed that the algal genome is split by a copy of viral sequences that have a high identity to EsV-1 DNA sequences. These fragments are interspersed with DNA repeats, pseudogenes and genes coding for products involved in DNA replication, integration and transposition. Some of these gene products are not encoded by EsV-1 but are present in the genome of other members of the NCLDV family. Further analysis suggests that the Ectocarpus algal genome contains traces of the integration of a large dsDNA viral genome; this genome could be the ancestor of the extant NCLDV genomes. Furthermore, several lines of evidence indicate that the EsV-1 genome might have originated in these viral DNA pieces, implying the existence of a complex integration and recombination system. A protein similar to a new class of tyrosine recombinases might be a key enzyme of this system. Our results support the hypothesis that some dsDNA viruses are monophyletic and evolved principally through genome reduction. Moreover, we hypothesize that phaeoviruses have probably developed an original replication system.
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The genome of the brown alga Ectocarpus siliculosus contains a series of viral DNA pieces, suggesting an ancient association with large dsDNA viruses
BMC Evolutionary Biology, 2008Co-Authors: Nicolas Delaroque, Wilhelm BolandAbstract:Background Ectocarpus siliculosus virus-1 (EsV-1) is a lysogenic dsDNA virus belonging to the super family of nucleocytoplasmic large DNA viruses (NCLDV) that infect Ectocarpus siliculosus, a marine filamentous brown alga. Previous studies indicated that the viral genome is integrated into the host DNA. In order to find the integration sites of the viral genome, a genomic library from EsV-1-infected algae was screened using labelled EsV-1 DNA. Several fragments were isolated and some of them were sequenced and analyzed in detail.
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The Complete DNA Sequence of the Ectocarpus siliculosus Virus EsV-1 Genome
Virology, 2001Co-Authors: Nicolas Delaroque, G. Bothe, T. M. Pohl, Dieter Müller, Rolf Knippers, Wilhelm BolandAbstract:The Ectocarpus siliculosus Virus-1, EsV-1, is the type-species of a genus of Phycodnaviridae, the phaeoviruses, infecting marine filamentous brown algae. The EsV-1 genome of 335,593 bp contains tandem and dispersed repetitive elements in addition to a large number of open reading frames of which 231 are currently counted as genes. Many genes can be assigned to functional groups involved in DNA synthesis, DNA integration, transposition, and polysaccharide metabolism. Furthermore, EsV-1 contains components of a surprisingly complex signal transduction system with six different hybrid histidine protein kinases and four putative serine/threonine protein kinases. Several other genes encode polypeptides with protein–protein interaction domains. However, 50% of the predicted genes have no counterparts in data banks. Only 28 of the 231 identified genes have significant sequence similarities to genes of the Chlorella virus PBCV-1, another phycodnavirus. To our knowledge, the EsV-1 genome is the largest viral DNA sequenced to date.
Eric P Miller - One of the best experts on this subject based on the ideXlab platform.
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emission of volatile halogenated compounds speciation and localization of bromine and iodine in the brown algal genome model Ectocarpus siliculosus
Journal of Biological Inorganic Chemistry, 2018Co-Authors: Frithjof C Kupper, Lucy J Carpenter, Chiaki Toyama, Eric P Miller, Stephen J Andrews, Claire Hughes, Wolfram Meyerklaucke, Yasuyuki Muramatsu, Martin C FeitersAbstract:This study explores key features of bromine and iodine metabolism in the filamentous brown alga and genomics model Ectocarpus siliculosus. Both elements are accumulated in Ectocarpus, albeit at much lower concentration factors (2-3 orders of magnitude for iodine, and < 1 order of magnitude for bromine) than e.g. in the kelp Laminaria digitata. Iodide competitively reduces the accumulation of bromide. Both iodide and bromide are accumulated in the cell wall (apoplast) of Ectocarpus, with minor amounts of bromine also detectable in the cytosol. Ectocarpus emits a range of volatile halogenated compounds, the most prominent of which by far is methyl iodide. Interestingly, biosynthesis of this compound cannot be accounted for by vanadium haloperoxidase since the latter have not been found to catalyze direct halogenation of an unactivated methyl group or hydrocarbon so a methyl halide transferase-type production mechanism is proposed.
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Emission of volatile halogenated compounds, speciation and localization of bromine and iodine in the brown algal genome model Ectocarpus siliculosus
JBIC Journal of Biological Inorganic Chemistry, 2018Co-Authors: Eric P Miller, Stephen J Andrews, Claire Hughes, Yasuyuki Muramatsu, Martin C Feiters, Wolfram Meyer-klaucke, Carl J. CarranoAbstract:This study explores key features of bromine and iodine metabolism in the filamentous brown alga and genomics model Ectocarpus siliculosus. Both elements are accumulated in Ectocarpus, albeit at much lower concentration factors (2-3 orders of magnitude for iodine, and
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surface bound iron a metal ion buffer in the marine brown alga Ectocarpus siliculosus
Journal of Experimental Botany, 2014Co-Authors: Eric P Miller, Frithjof C Kupper, Wolfram Meyerklaucke, Lars H. Böttger, Berthold F. Matzanke, Aruna J Weerasinghe, Alvin L Crumbliss, Carl J. CarranoAbstract:Although the iron uptake and storage mechanisms of terrestrial/higher plants have been well studied, the corresponding systems in marine algae have received far less attention. Studies have shown that while some species of unicellular algae utilize unique mechanisms of iron uptake, many acquire iron through the same general mechanisms as higher plants. In contrast, the iron acquisition strategies of the multicellular macroalgae remain largely unknown. This is especially surprising since many of these organisms represent important ecological and evolutionary niches in the coastal marine environment. It has been well established in both laboratory and environmentally derived samples, that a large amount of iron can be ‘non-specifically’ adsorbed to the surface of marine algae. While this phenomenon is widely recognized and has prompted the development of experimental protocols to eliminate its contribution to iron uptake studies, its potential biological significance as a concentrated iron source for marine algae is only now being recognized. This study used an interdisciplinary array of techniques to explore the nature of the extensive and powerful iron binding on the surface of both laboratory and environmental samples of the marine brown alga Ectocarpus siliculosus and shows that some of this surface-bound iron is eventually internalized. It is proposed that the surfacebinding properties of E. siliculosus allow it to function as a quasibiological metal ion ‘buffer’, allowing iron uptake under the widely varying external iron concentrations found in coastal marine environments.
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Atypical iron storage in marine brown algae: a multidisciplinary study of iron transport and storage in Ectocarpus siliculosus
Journal of Experimental Botany, 2012Co-Authors: Lars H. Böttger, Eric P Miller, Christian Andresen, Berthold F. Matzanke, Carl J. CarranoAbstract:Iron is an essential element for all living organisms due to its ubiquitous role in redox and other enzymes, especially in the context of respiration and photosynthesis. The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood, with two basic strategies for iron uptake being distinguished: strategy I plants use a mechanism involving induction of Fe(III)-chelate reductase (ferrireductase) and Fe(II) transporter proteins, while strategy II plants utilize high-affinity, iron-specific, binding compounds called phytosiderophores. In contrast, little is known about the corresponding systems in marine, plant-like lineages, particularly those of multicellular algae (seaweeds). Herein the first study of the iron uptake and storage mechanisms in the brown alga Ectocarpus siliculosus is reported. Genomic data suggest that Ectocarpus may use a strategy I approach. Short-term radio-iron uptake studies verified that iron is taken up by Ectocarpus in a time- and concentration-dependent manner consistent with an active transport process. Upon long-term exposure to 57Fe, two metabolites have been identified using a combination of Mossbauer and X-ray absorption spectroscopies. These include an iron–sulphur cluster accounting for ~26% of the total intracellular iron pool and a second component with spectra typical of a polymeric (Fe3+O6) system with parameters similar to the amorphous phosphorus-rich mineral core of bacterial and plant ferritins. This iron metabolite accounts for ~74% of the cellular iron pool and suggests that Ectocarpus contains a non-ferritin but mineral-based iron storage pool.
