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Wim Vyverman - One of the best experts on this subject based on the ideXlab platform.
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Pheromone Mediated Sexual Reproduction of Pennate Diatom Cylindrotheca closterium
Journal of Chemical Ecology, 2021Co-Authors: Franziska Klapper, Wim Vyverman, Sien Audoor, Georg PohnertAbstract:Benthic diatoms dominate primary production in marine subtidal and intertidal environments. Their extraordinary species diversity and ecological success is thought to be linked with their predominantly heterothallic sexual reproduction. Little is known about pheromone involvement during mating of pennate diatoms. Here we describe pheromone guided mating in the coastal raphid diatom Cylindrotheca closterium . We show that the two mating types (mt^+ and mt^−) have distinct functions. Similar to other benthic diatoms, mt^+ cells are searching for the mt^− cells to pair. To enhance mating efficiency mt^− exudes an attraction pheromone which we proved by establishing a novel capillary assay. Further, two more pheromones produced by mt^− promote the sexual events. One arrests the cell cycle progression of mt^+ while the other induces gametogenesis of mt^+. We suggest that C. closterium shares a functionally similar pheromone system with other pennate diatoms like S eminavis robusta and Pseudostaurosira trainorii which synchronize sexual events and mate attraction. Remarkably, we found no evidence of mt^+ producing pheromones, which differentiates C. closterium from other pennates and suggests a less complex pheromone system in C. closterium .
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Thermal Niche Differentiation in the Benthic Diatom Cylindrotheca closterium (Bacillariophyceae) Complex.
Frontiers in microbiology, 2019Co-Authors: Willem Stock, Bart Vanelslander, Koen Sabbe, Wim Vyverman, Franziska Rüdiger, Ulf KarstenAbstract:Coastal waters are expected to undergo severe warming in the coming decades. Very little is known about how diatoms, the dominant primary producers in these habitats, will cope with these changes. We investigated the thermal niche of Cylindrotheca closterium, a widespread benthic marine diatom, using 24 strains collected over a wide latitudinal gradient. A multi-marker phylogeny in combination with a species delimitation approach shows that C. closterium represents a (pseudo)cryptic species complex, and this is reflected in distinct growth response patterns in terms of optimum growth temperature, maximum growth rate, and thermal niche width. Strains from the same clade displayed a similar thermal response, suggesting niche conservation between closely related strains. Due to their lower maximum growth rate and smaller thermal niche width, we expect the polar species to be particularly sensitive to warming, and, in the absence of adaptation, to be replaced with species from lower latitudes.
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Heterothallic sexual reproduction in the model diatom Cylindrotheca
European Journal of Phycology, 2013Co-Authors: Pieter Vanormelingen, Rosa Trobajo, Jeroen Gillard, Bart Vanelslander, Koen Sabbe, Shinya Sato, Wim VyvermanAbstract:Cylindrotheca is one of the main model diatoms for ecophysiological and silicification research and is among the few diatoms for which a transformation protocol is available. Knowledge of its life cycle is not available, however, although sexual reproduction has been described for several related genera. In this study, 16 Cylindrotheca closterium strains from a single rbcL lineage were used to describe the life cycle of this marine diatom, including the sexual process and mating system. Similar to other Bacillariaceae, sexual reproduction was induced by the presence of a suitable mating partner, with two gametes produced per gametangium, resulting in two auxospores per gametangial pair. Differences with other Bacillariaceae include details of cell pairing, gamete behaviour, auxospore orientation and chloroplast configuration, and perizonium structure. The mating system is heterothallic, since strains fell into two mating type groups, with several strains of one mating type occasionally displaying intraclo...
F R Tabita - One of the best experts on this subject based on the ideXlab platform.
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a hybrid ribulosebisphosphate carboxylase oxygenase enzyme exhibiting a substantial increase in substrate specificity factor
Biochemistry, 1992Co-Authors: Betsy A Read, F R TabitaAbstract:Two hybrid ribulose-1,5 bisphosphate carboxylase/oxygenase (RubisCO) enzymes were constructed using RubisCO small subunit genes (rbcS) from two eucaryotic marine organisms, Cylindrotheca sp. N1 and Olisthodiscus luteus, cloned downstream of the RubisCO large subunit gene (rbcL) of the cyanobacterium Synechococcus PCC 6301. The expression products synthesized by Escherichia coli JM107 (pVTAC223 and pANOLI) were purified and examined by polyacrylamide gel electrophoresis and compared to the purified products generated by E. coli MV1190 (pBGL710), containing cyanobacterial rbcL and rbcS genes. Both Cylindrotheca and Olisthodiscus small subunits were able to assemble in vivo with the Synechococcus large subunit octamer to form heterologous hexadecameric L8S8 enzymes, the pVTAC223 and pANOLI hybrid enzymes, respectively. Like the Synechococcus RubisCO, the hybrid enzymes were rapidly activated by Mg2+ plus HCO3-, even in the presence of RuBP. The hybrid enzymes, however, were considerably more sensitive to the competitive inhibitor 6-phosphogluconate. Detailed kinetic analysis indicated that while the carboxylase activity of both chimeric enzymes was severely reduced, in the case of the pVTAC223 hybrid enzyme, the degree of partitioning between carboxylation and oxygenation was increased nearly 60% relative to the Synechococcus RubisCO. Other kinetic properties, including the Michaelis constants for the gaseous substrates and RuBP, were altered in the hybrid proteins. These studies also led to the finding that the substrate specificity factor of the Cylindrotheca RubisCO is unusually high.
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acyl carrier protein derived sequence encoded by the chloroplast genome in the marine diatom Cylindrotheca sp strain n1
Journal of Biological Chemistry, 1991Co-Authors: Shinrong Hwang, F R TabitaAbstract:The chloroplast genome of chromophytic and rhodophytic algae differs from the plastid genome of plants and green algae in that it encodes the gene for the small subunit (rbcS) of ribulose 1,5-bisphosphate carboxylase/oxygenase. Hybridization studies indicated that there was a second region of chloroplast DNA from the marine diatom Cylindrotheca sp. strain N1 that strongly hybridized to a previously isolated Cylindrotheca fragment that contained the rbcS gene and flanking sequences. Subsequent determination of the oligonucleotide sequence of this second chloroplast DNA fragment, however, indicated that hybridization was due to identical sequences 3' to the previously cloned Cylindrotheca chloroplast rbcL rbcS genes. Sequences derived from the 5' end of the second chloroplast DNA fragment contained a short open reading frame of 80 amino acids which was found to be highly homologous to bacterial acyl carrier protein and nuclear-encoded acyl carrier protein from plants. Amino acid residues in the environment of Ser-36 of the Escherichia coli protein, which is bound to a 4'-phosphopantetheine moiety, are virtually identical in the Cylindrotheca deduced sequence and all other sources of this protein. Unlike plant acyl carrier-deduced amino acid sequences, there was no leader peptide sequence found for the presumptive Cylindrotheca protein, consistent with the location of this DNA fragment on the chloroplast genome of this organism. DNA encoding the putative acyl carrier protein gene and rbcS thus represent two genes that are chloroplast-encoded in the chromophytic marine diatom Cylindrotheca, a significant departure from the organization of such genes in plants.
Ulf Karsten - One of the best experts on this subject based on the ideXlab platform.
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Salinity tolerance in biogeographically different strains of the marine benthic diatom Cylindrotheca closterium (Bacillariophyceae)
Journal of Applied Phycology, 2020Co-Authors: Karin Glaser, Ulf KarstenAbstract:In coastal zones, salinity is commonly a rather local environmental factor that can be highly variable. Future climate change scenarios indicate for many coastal regions besides warming also changes in current salinity regime due to less precipitation, higher evaporation, or more freshwater run-off, resulting in decreasing or increasing saline conditions. The soft bottom of shallow water coastal zones is typically inhabited by benthic diatoms which cover as photosynthetic biofilms extensive areas of sediments. Cylindrotheca closterium is a cosmopolitan and abundant taxon of such communities, and is widely used as a benthic diatom model system. Nevertheless, comprehensive ecophysiological data on the salinity tolerance of this ecologically important benthic species are still missing. Therefore, the main goal was to investigate the salinity tolerance in 6 strains of C. closterium from 5 different clades and from marine to brackish habitats. An analysis of growth as function of salinity allowed the evaluation of tolerance limits, growth optima, and acclimation abilities of individual strains. The data documented isolate-specific growth response patterns and rather broad tolerance widths among the six strains of C. closterium , which point to strong genotypic differentiation. The results of the phylogenetic network analysis indicate several well separated grades within C. closterium , thereby supporting the earlier suggestion of a cryptic species complex.
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Thermal Niche Differentiation in the Benthic Diatom Cylindrotheca closterium (Bacillariophyceae) Complex.
Frontiers in microbiology, 2019Co-Authors: Willem Stock, Bart Vanelslander, Koen Sabbe, Wim Vyverman, Franziska Rüdiger, Ulf KarstenAbstract:Coastal waters are expected to undergo severe warming in the coming decades. Very little is known about how diatoms, the dominant primary producers in these habitats, will cope with these changes. We investigated the thermal niche of Cylindrotheca closterium, a widespread benthic marine diatom, using 24 strains collected over a wide latitudinal gradient. A multi-marker phylogeny in combination with a species delimitation approach shows that C. closterium represents a (pseudo)cryptic species complex, and this is reflected in distinct growth response patterns in terms of optimum growth temperature, maximum growth rate, and thermal niche width. Strains from the same clade displayed a similar thermal response, suggesting niche conservation between closely related strains. Due to their lower maximum growth rate and smaller thermal niche width, we expect the polar species to be particularly sensitive to warming, and, in the absence of adaptation, to be replaced with species from lower latitudes.
Lucas J Stal - One of the best experts on this subject based on the ideXlab platform.
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Uptake and excretion of dimethylsulphoniopropionate is driven by salinity changes in the marine benthic diatom Cylindrotheca closterium
European Journal of Phycology, 2003Co-Authors: S. A. Van Bergeijk, C. Van Der Zee, Lucas J StalAbstract:Long-term ( ⩽ 14 d) and short-term ( ⩽ 9 h) effects of salinity on the dimethylsulphoniopropionate (DMSP) content of the marine benthic diatom Cylindrotheca closterium were investigated. When grown in batch cultures at various salinities, intracellular DMSP increased from 13.8 to 823 μmol g − 1 protein at salinities of 11 and 44 psu, respectively, but increasing salinity further did not result in a higher content. Instead, the concentration of the amino acid proline increased from 17.5 to 149.6 μmol g − 1 protein when salinity increased from 33 to 55, indicating that this compound is more important than DMSP as an osmoprotectant at higher salinities. In addition, another, hitherto unidentified, compound increased strongly in response to salinity. During salinity up- and down-shock experiments, changes in the DMSP content of C. closterium corresponded with the changes in salinity. DMSP was excreted into the medium after salinity down-shock, while salinity up-shock induced a slow synthesis of DMSP. However,...
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physical characterization and diel dynamics of different fractions of extracellular polysaccharides in an axenic culture of a benthic diatom
European Journal of Phycology, 2002Co-Authors: J F C De Brouwer, K. Wolfstein, Lucas J StalAbstract:The excretion of extracellular polymeric substances (EPS) by an axenic culture of the benthic diatom Cylindrotheca closterium was investigated. Two sequential extraction steps proved to be suficient to remove the bulk of the EPS present. Soluble EPS was recovered by a simple centrifugation step and represented a fraction that was not or was only loosely associated with diatom cells. For the extraction of bound EPS, different procedures were compared. The best results were obtained using distilled water as extraction solvent (1 h, 30 °C). The sugars that were recovered using this procedure were typically associated with aggregates of diatoms. In addition to the distinct differences in localization of the different types of EPS, their temporal dynamics differed in relation to the light–dark cycle. Soluble EPS were continuously released into the medium at a rate of 1.6 pg cell−1 day−1. In contrast, the production of bound EPS was highly light-dependent. In the dark, this bound EPS rapidly disappeared, probab...
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isolation and characterization of extracellular polysaccharides from the epipelic diatoms Cylindrotheca closterium and navicula salinarum
European Journal of Phycology, 1999Co-Authors: N. Staats, Lucas J Stal, Ben De Winder, Luuc R MurAbstract:The production and composition of extracellular polymeric substances (EPS) in axenic batch cultures of the benthic marine epipelic diatoms Navicula salinarum and Cylindrotheca closterium were investigated. EPS was secreted into the medium and the bulk was loosely associated with the cells. Neither N. salinarum nor C. closterium formed a well-defined polysaccharide capsule. EPS of both N. salinarum and C. closterium consisted predominantly of polysaccharide but small quantities of protein were present as well. EPS also contained uronic acids and SO4 −2 groups. Analysis of monosaccharides using gas chromatography showed that for both species glucose and xylose were the main constituents, but several other monosaccharides were present in smaller quantities. Two fractions of EPS were distinguished: a small amount was secreted into the medium and a second fraction was extracted in water at 30 °C. For both species the two fractions differed somewhat in composition, indicating that they represented two different...
Nils Kroger - One of the best experts on this subject based on the ideXlab platform.
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pscd domains of pleuralin 1 from the diatom Cylindrotheca fusiformis nmr structures and interactions with other biosilica associated proteins
Structure, 2016Co-Authors: Silvia De Sanctis, Nils Kroger, Manfred Sumper, Rainer Deutzmann, Michael Wenzler, Wilhelm M Malloni, Patrick Zadravec, Eike BrunnerAbstract:Summary Diatoms are eukaryotic unicellular algae characterized by silica cell walls and associated with three unique protein families, the pleuralins, frustulins, and silaffins. The NMR structure of the PSCD4 domain of pleuralin-1 from Cylindrotheca fusiformis contains only three short helical elements and is stabilized by five unique disulfide bridges. PSCD4 contains two binding sites for Ca 2+ ions with millimolar affinity. NMR-based interaction studies show an interaction of the domain with native silaffin-1A as well as with α-frustulins. The interaction sites of the two proteins mapped on the PSCD4 structure are contiguous and show only a small overlap. A plausible functional role of pleuralin could be to bind simultaneously silaffin-1A located inside the cell wall and α-frustulin coating the cell wall, thus connecting the interfaces between hypotheca and epitheca at the girdle bands. Restrained molecular dynamics calculations suggest a bead-chain-like structure of the central part of pleuralin-1.
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solid state 29si mas nmr studies of diatoms structural characterization of biosilica deposits
Analytical and Bioanalytical Chemistry, 2003Co-Authors: R Bertermann, Nils Kroger, R TackeAbstract:Four different diatom species (Chaetoceros debilis, Chaetoceros didymum, Cylindrotheca fusiformis, Nitzschia angularis) were studied by solid-state 29Si MAS NMR spectroscopy. To determine the Q2:Q3:Q4 ratios in the biosilica deposits of the diatoms, quantitative 29Si MAS NMR experiments were performed. This analysis did not reveal any differences regarding the molecular architecture of the silica (i.e. the degree of condensation of the SiOH units (2 ≡SiOH → ≡Si–O–Si≡ + H2O)) from the different diatom species. However, complete cells showed significantly smaller Q4:Q3 ratios (1.8–1.9) than extracted cell walls (2.5–2.8), indicating the existence of intracellular pools of less condensed silica.
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silica precipitating peptides from diatoms the chemical structure of silaffin 1a from Cylindrotheca fusiformis
Journal of Biological Chemistry, 2001Co-Authors: Nils Kroger, Rainer Deutzmann, Manfred SumperAbstract:Two silica-precipitating peptides, silaffin-1A1 and-1A2, both encoded by thesil1 gene from the diatom Cylindrotheca fusiformis, were extracted from cell walls and purified to homogeneity. The chemical structures were determined by protein chemical methods combined with mass spectrometry. Silaffin-1A1 and -1A2 consist of 15 and 18 amino acid residues, respectively. Each peptide contains a total of four lysine residues, which are all found to be post-translationally modified. In silaffin-1A2 the lysine residues are clustered in two pairs in which the e-amino group of the first residue is linked to a linear polyamine consisting of 5 to 11N-methylated propylamine units, whereas the second lysine is converted to e-N,N-dimethyllysine. Silaffin-1A1 contains only a single lysine pair exhibiting the same structural features. One of the two remaining lysine residues was identified as e-N,N,N-trimethyl-δ-hydroxylysine, a lysine derivative containing a quaternary ammonium group. The fourth lysine residue again is linked to a long-chain polyamine. Silaffin-1A1 is the first peptide shown to contain e-N,N,N-trimethyl-δ-hydroxylysine. In vitro, both peptides precipitate silica nanospheres within seconds when added to a monosilicic acid solution.
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pleuralins are involved in theca differentiation in the diatom Cylindrotheca fusiformis
Protist, 2000Co-Authors: Nils Kroger, Richard WetherbeeAbstract:Diatom cells are encased within a silica-based cell wall (frustule) that serves as armour-like protection for the enclosed protoplast. Maintaining the integrity of the frustule requires a precise coupling between the biogenesis of new frustule components and the cell cycle. Thus far, the molecular mechanisms by which this coupling is achieved are unknown. This study demonstrates that pleuralins (formerly HEPs), a previously characterized family of diatom cell wall proteins, are involved in cell cycle-dependent frustule development. The frustule is made up of two, overlapping half-shells termed the epitheca and hypotheca. Both thecae are morphologically identical, yet immunolocalisation with anti-pleuralin antibodies demonstrates that their protein composition is clearly different. During interphase, pleuralins are associated only with the epitheca, where they are confined to the inner surface of the terminal elements (pleural bands) in the region of overlap with the hypotheca. At cell division, pleuralins also become associated with the newly formed pleural bands of the hypotheca. Remarkably, this process is concomitant with the functional conversion of the parental hypotheca into the epitheca of one of the progeny cells. These results indicate that developmentally controlled association of pleuralins with the frustule is involved in hypotheca-epitheca differentiation, which is a crucial process to ensure proper frustule development.
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a new calcium binding glycoprotein family constitutes a major diatom cell wall component
The EMBO Journal, 1994Co-Authors: Nils Kroger, Christian Bergsdorf, Manfred SumperAbstract:Diatoms possess silica-based cell walls with species-specific structures and ornamentations. Silica deposition in diatoms offers a model to study the processes involved in biomineralization. A new wall is produced in a specialized vesicle (silica deposition vesicle, SDV) and secreted. Thus proteins involved in wall biogenesis may remain associated with the mature cell wall. Here it is demonstrated that EDTA treatment removes most of the proteins present in mature cell walls of the marine diatom Cylindrotheca fusiformis. A main fraction consists of four related glycoproteins with a molecular mass of approximately 75 kDa. These glycoproteins were purified to homogeneity. They consist of repeats of Ca2+ binding domains separated by polypeptide stretches containing hydroxyproline. The proteins in the EDTA extract aggregate and precipitate in the presence of Ca2+. Immunological studies detected related proteins in the cell wall of the freshwater diatom Navicula pelliculosa, indicating that these proteins represent a new family of proteins that are involved in the biogenesis of diatom cell walls.
