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Bente Edvardsen - One of the best experts on this subject based on the ideXlab platform.
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Haptophyte diversity and vertical distribution explored by 18s and 28s ribosomal rna gene metabarcoding and scanning electron microscopy
Journal of Eukaryotic Microbiology, 2017Co-Authors: Sandra Granstadniczenko, Elianne Dunthorn Egge, Luka Supraha, Bente EdvardsenAbstract:: Haptophyta encompasses more than 300 species of mostly marine pico- and nanoplanktonic flagellates. Our aims were to investigate the Oslofjorden Haptophyte diversity and vertical distribution by metabarcoding, and to improve the approach to study Haptophyte community composition, richness and proportional abundance by comparing two rRNA markers and scanning electron microscopy (SEM). Samples were collected in August 2013 at the Outer Oslofjorden, Norway. Total RNA/cDNA was amplified by Haptophyte-specific primers targeting the V4 region of the 18S, and the D1-D2 region of the 28S rRNA. Taxonomy was assigned using curated Haptophyte reference databases and phylogenetic analyses. Both marker genes showed Chrysochromulinaceae and Prymnesiaceae to be the families with highest number of Operational Taxonomic Units (OTUs), as well as proportional abundance. The 18S rRNA data set also contained OTUs assigned to eight supported and defined clades consisting of environmental sequences only, possibly representing novel lineages from family to class. We also recorded new species for the area. Comparing coccolithophores by SEM with metabarcoding shows a good correspondence with the 18S rRNA gene proportional abundances. Our results contribute to link morphological and molecular data and 28S to 18S rRNA gene sequences of Haptophytes without cultured representatives, and to improve metabarcoding methodology.
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Haptophyte diversity and vertical distribution explored by 18s and 28s ribosomal rna gene metabarcoding and scanning electron microscopy
Journal of Eukaryotic Microbiology, 2017Co-Authors: Sandra Granstadniczenko, Elianne Dunthorn Egge, Luka Supraha, Bente EdvardsenAbstract:Haptophyta encompasses more than 300 species of mostly marine pico- and nanoplanktonic flagellates. Our aims were to investigate the Oslofjorden Haptophyte diversity and vertical distribution by metabarcoding, and to improve the approach to study Haptophyte community composition, richness and proportional abundance by comparing two rRNA markers and scanning electron microscopy (SEM). Samples were collected in August 2013 at the Outer Oslofjorden, Norway. Total RNA/cDNA was amplified by Haptophyte-specific primers targeting the V4 region of the 18S, and the D1-D2 region of the 28S rRNA. Taxonomy was assigned using curated Haptophyte reference databases and phylogenetic analyses. Both marker genes showed Chrysochromulinaceae and Prymnesiaceae to be the families with highest number of Operational Taxonomic Units (OTUs), as well as proportional abundance. The 18S rRNA data set also contained OTUs assigned to eight supported and defined clades consisting of environmental sequences only, possibly representing novel lineages from family to class. We also recorded new species for the area. Comparing coccolithophores by SEM with metabarcoding shows a good correspondence with the 18S rRNA gene proportional abundances. Our results contribute to link morphological and molecular data and 28S to 18S rRNA gene sequences of Haptophytes without cultured representatives, and to improve metabarcoding methodology.
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Seasonal Dynamics of Haptophytes and dsDNA Algal Viruses Suggest Complex Virus-Host Relationship
Viruses, 2017Co-Authors: Torill Vik Johannessen, Elianne Dunthorn Egge, Gunnar Bratbak, Aud Larsen, Antonio Pagarete, Bente Edvardsen, Ruthanne SandaaAbstract:Viruses influence the ecology and diversity of phytoplankton in the ocean. Most studies of phytoplankton host–virus interactions have focused on bloom-forming species like Emiliania huxleyi or Phaeocystis spp. The role of viruses infecting phytoplankton that do not form conspicuous blooms have received less attention. Here we explore the dynamics of phytoplankton and algal viruses over several sequential seasons, with a focus on the ubiquitous and diverse phytoplankton division Haptophyta, and their double-stranded DNA viruses, potentially with the capacity to infect the Haptophytes. Viral and phytoplankton abundance and diversity showed recurrent seasonal changes, mainly explained by hydrographic conditions. By 454 tag-sequencing we revealed 93 unique Haptophyte operational taxonomic units (OTUs), with seasonal changes in abundance. Sixty-one unique viral OTUs, representing Megaviridae and Phycodnaviridae, showed only distant relationship with currently isolated algal viruses. Haptophyte and virus community composition and diversity varied substantially throughout the year, but in an uncoordinated manner. A minority of the viral OTUs were highly abundant at specific time-points, indicating a boom-bust relationship with their host. Most of the viral OTUs were very persistent, which may represent viruses that coexist with their hosts, or able to exploit several host species.
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Haptophyta
Handbook of the Protists, 2016Co-Authors: Wenche Eikrem, Linda K. Medlin, Ian Probert, Jorijntje Henderiks, Sebastian Rokitta, Björn Rost, Jahn Throndsen, Bente EdvardsenAbstract:Haptophyta are predominantly planktonic and phototrophic organisms that have their main distribution in marine environments worldwide. They are a major component of the microbial ecosystem, some form massive blooms and some are toxic. Haptophytes are significant players in the global carbonate cycle through photosynthesis and calcification. They are characterized by the haptonema, a third appendage used for attachment and food handling, two similar flagella, two golden-brown chloroplasts, and organic body scales that serve in species identification. Coccolithophores have calcified scales termed coccoliths. Phylogenetically Haptophyta form a well-defined group and are divided into two classes Pavlovophyceae and Coccolithophyceae (Prymnesiophyceae). Currently, about 330 species are described. Environmental DNA sequencing shows high Haptophyte diversity in the marine pico- and nanoplankton, of which many likely represent novel species and lineages. Haptophyte diversity is believed to have peaked in the past and their presence is documented in the fossil record back to the Triassic, approximately 225 million years ago. Some biomolecules of Haptophyte origin are extraordinarily resistant to decay and are thus used by geologists as sedimentary proxies of past climatic conditions
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Seasonal diversity and dynamics of Haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing
Molecular Ecology, 2015Co-Authors: Elianne Sirnæs Egge, Ruthanne Sandaa, Torill Vik Johannessen, Aud Larsen, Wenche Eikrem, Tom Andersen, Lucie Bittner, Bente EdvardsenAbstract:Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on Haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2years, and the Haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September-October (autumn) and lowest in April-May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3-5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of Haptophytes in North Atlantic coastal waters. See also the Perspective by Massana
Marcel T. J. Van Der Meer - One of the best experts on this subject based on the ideXlab platform.
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Impact of metabolic pathways and salinity on the hydrogen isotope ratios of Haptophyte lipids
2019Co-Authors: Gabriella M. Weiss, Stefan Schouten, Jaap S. Sinninghe Damsté, Sebastian Kasper, David Chivall, Hideto Nakamura, Fiz Da Costa, Philippe Soudant, Marcel T. J. Van Der MeerAbstract:Abstract. Hydrogen isotope ratios of biomarkers have been shown to reflect water isotope ratios, and in some cases correlate significantly with salinity. The δ2H-salinity relationship is best studied for long-chain alkenones, biomarkers for Haptophyte algae, and is known to be influenced by a number of different environmental parameters. It is not fully known why δ2H ratios of lipids retain a correlation to salinity, and whether this is a general feature for other lipids produced by Haptophyte algae. Here, we analyzed δ2H ratios of three fatty acids, brassicasterol, long-chain C37 alkenones and phytol from three different Haptophyte species grown over a range of salinities. Lipids synthesized in the cytosol, or relying on precursors of cytosolic origin, show a correlation between their δ2H ratios and salinity. In contrast, biosynthesis in the chloroplast, or utilizing precursors created in the chloroplast, yields lipids that do not show a correlation between δ2H ratios and salinity. This leads to the conclusion that location of metabolism is the first-order control on the salinity signal retained in δ2H ratios of certain lipids. Additionally, we found that δ2H ratios of alkenones from batch cultures of the Group II Haptophyte species Tisochrysis lutea correlate positively with temperature, contrary to findings from cultures of Group III Haptophytes, but retain a similar response to nutrient availability in line with other Group III Haptophytes.
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the effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal Haptophyte algae
Geochimica et Cosmochimica Acta, 2014Co-Authors: David Chivall, Stefan Schouten, Jaap Sinninghe S Damste, Daniela Mboule, Danielle Sinkeschoen, Marcel T. J. Van Der MeerAbstract:The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine Haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity has previously only been determined during exponential growth, whilst it is not yet known in which growth phases natural Haptophyte populations predominantly exist. We have therefore determined the relationship between the fractionation factor, αalkenones-water, and salinity for C37 alkenones produced in different growth phases of batch cultures of the major alkenone-producing coastal Haptophytes Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) over a range in salinity from ca. 10 to 35. αalkenones-water was similar in both species, ranging over 0.841-0.900 for I. galbana and 0.838-0.865 for C. lamellosa. A strong (0.85≤R2≤0.97; p<0.0001) relationship between salinity and fractionation factor was observed in both species at all growth phases investigated. This suggests that alkenone δD has the potential to be used as a salinity proxy in neritic areas where Haptophyte communities are dominated by these coastal species. However, there was a marked difference in the sensitivity of αalkenones-water to salinity between different growth phases: in the exponential growth phase of I. galbana, αalkenones-water increased by 0.0019 per salinity unit (S-1), but was less sensitive at 0.0010 and 0.0008S-1 during the stationary and decline phases, respectively. Similarly, in C. lamellosa αalkenones-water increased by 0.0010S-1 in the early stationary phase and by 0.0008S-1 during the late stationary phase. Assuming the shift in sensitivity of αalkenones-water to salinity observed at the end of exponential growth in I. galbana is similar in other alkenone-producing species, the predominant growth phase of natural populations of Haptophytes will affect the sensitivity of the alkenone salinity proxy. The proxy is likely to be most sensitive to salinity when alkenones are produced in a state similar to exponential growth. © 2014 Elsevier Ltd.
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The effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal Haptophyte algae
Geochimica et Cosmochimica Acta, 2014Co-Authors: David Chivall, Stefan Schouten, Jaap S. Sinninghe Damsté, Daniela M'boule, Daniëlle Sinke-schoen, Marcel T. J. Van Der MeerAbstract:The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine Haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity has previously only been determined during exponential growth, whilst it is not yet known in which growth phases natural Haptophyte populations predominantly exist. We have therefore determined the relationship between the fractionation factor, αalkenones-water, and salinity for C37 alkenones produced in different growth phases of batch cultures of the major alkenone-producing coastal Haptophytes Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) over a range in salinity from ca. 10 to 35. αalkenones-water was similar in both species, ranging over 0.841-0.900 for I. galbana and 0.838-0.865 for C. lamellosa. A strong (0.85≤R2≤0.97; p
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Salinity dependent hydrogen isotope fractionation in alkenones produced by coastal and open ocean Haptophyte algae
Geochimica et Cosmochimica Acta, 2014Co-Authors: Daniela M'boule, Stefan Schouten, Jaap S. Sinninghe Damsté, David Chivall, Daniëlle Sinke-schoen, Marcel T. J. Van Der MeerAbstract:Abstract The hydrogen isotope fractionation in alkenones produced by Haptophyte algae is a promising new proxy for paleosalinity reconstructions. To constrain and further develop this proxy the coastal Haptophyte Isochrysis galbana and the open ocean Haptophyte alga Emiliania huxleyi were cultured at different salinities. The fractionation factor, αalkenones–water, ranged between 0.853 and 0.902 for I. galbana and 0.789 and 0.822 for E. huxleyi. The results show a strong linear correlation between the fractionation factor α and salinity for E. huxleyi, in agreement with earlier studies, but also for I. galbana. Both Haptophytes show the same response to changes in salinity, represented by the slopes of the α–salinity relationship (∼0.002 per salinity unit). This suggests that the same process, in both coastal as well as open ocean Haptophytes, is responsible for reducing fractionation with increasing salinity. However, there is a significant difference in absolute isotope fractionation between E. huxleyi and I. galbana, i.e. E. huxleyi produces alkenones which are 90‰ more depleted in D under the same culturing conditions than I. galbana. Our data suggest that the δD of alkenones can be used to reconstruct relative shifts in paleosalinity in coastal as well as open ocean environments with careful consideration of species composition and other complicating factors especially in coastal regions.
Rose Ann Cattolico - One of the best experts on this subject based on the ideXlab platform.
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Chrysochromulina: Genomic assessment and taxonomic diagnosis of the type species for an oleaginous algal clade
Algal Research, 2019Co-Authors: Blake T. Hovde, Chloe R. Deodato, Shawn R. Starkenburg, Steven B. Barlow, Robert A. Andersen, Rose Ann CattolicoAbstract:Abstract Background Until recent studies documented their extensive contribution to primary productivity and carbon sequestration, Haptophytes remained underappreciated players in global ecosystem processes. Contemporary analyses, augmented by the use of molecular probes, show the Haptophyte taxon Chrysochromulina to be seminal to the ecology of both marine and freshwater ecosystems. Unfortunately, description for the type species for this clade remains enigmatic. Results Chrysochromulina parva Lackey was re-isolated from Big Walnut Creek (Ohio), the site where the original isolate was obtained. The sequenced haploid genome of this organism is 65.7 Mb in size. Several noteworthy nuclear-encoded genes identified include a novel ftsZ (mediates organelle division) that phylogenetically clusters with the Chloroarachniophytes. Also revealed, is a complement of genes associated with meiosis and DNA repair, indicating the presence of a sexual cycle in this alga. Mitochondrial genes lost to the nucleus include all extrinsic components of the nad complex, completing a punctate pattern of transfer that is observed among algal taxa. Comparison of the newly sequenced Chrysochromulina parva Lacky isolate was made with that of Chrysochromulina tobinii (59.1 Mb) – a fresh water strain isolated from a lake in Colorado. Conclusion Genomic analysis suggests that fresh water Chrysochromulina isolates, though geographically well separated, from a related clade. The name of the type species of Chrysochromulina parva Lacky is anchored with a lectotype and epitype, and the second isolate is described as Chrysochromulina tobinii sp. nov. Chrysochromulina represents a new, extremely tractable model organism for experimental studies. This oleaginous alga has a small genome and because it represents only the second Haptophyte taxon to be sequenced and assembled, presents new opportunity to examine the evolution of an algal taxon that plays an intrinsic role in ecosystem function.
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Extensive horizontal gene transfer, duplication, and loss of chlorophyll synthesis genes in the algae
BMC Evolutionary Biology, 2015Co-Authors: Heather M Hunsperger, Tejinder Randhawa, Rose Ann CattolicoAbstract:Background Two non-homologous, isofunctional enzymes catalyze the penultimate step of chlorophyll a synthesis in oxygenic photosynthetic organisms such as cyanobacteria, eukaryotic algae and land plants: the light-independent (LIPOR) and light-dependent (POR) protochlorophyllide oxidoreductases. Whereas the distribution of these enzymes in cyanobacteria and land plants is well understood, the presence, loss, duplication, and replacement of these genes have not been surveyed in the polyphyletic and remarkably diverse eukaryotic algal lineages. Results A phylogenetic reconstruction of the history of the POR enzyme (encoded by the por gene in nuclei) in eukaryotic algae reveals replacement and supplementation of ancestral por genes in several taxa with horizontally transferred por genes from other eukaryotic algae. For example, stramenopiles and Haptophytes share por gene duplicates of prasinophytic origin, although their plastid ancestry predicts a rhodophytic por signal. Phylogenetically, stramenopile por s appear ancestral to those found in Haptophytes, suggesting transfer from stramenopiles to Haptophytes by either horizontal or endosymbiotic gene transfer. In dinoflagellates whose plastids have been replaced by those of a Haptophyte or diatom, the ancestral por genes seem to have been lost whereas those of the new symbiotic partner are present. Furthermore, many chlorarachniophytes and peridinin-containing dinoflagellates possess por gene duplicates. In contrast to the retention, gain, and frequent duplication of algal por genes, the LIPOR gene complement (chloroplast-encoded chlL , chlN , and chlB genes) is often absent. LIPOR genes have been lost from Haptophytes and potentially from the euglenid and chlorarachniophyte lineages. Within the chlorophytes, rhodophytes, cryptophytes, heterokonts, and chromerids, some taxa possess both POR and LIPOR genes while others lack LIPOR. The gradual process of LIPOR gene loss is evidenced in taxa possessing pseudogenes or partial LIPOR gene compliments. No horizontal transfer of LIPOR genes was detected. Conclusions We document a pattern of por gene acquisition and expansion as well as loss of LIPOR genes from many algal taxa, paralleling the presence of multiple por genes and lack of LIPOR genes in the angiosperms. These studies present an opportunity to compare the regulation and function of por gene families that have been acquired and expanded in patterns unique to each of various algal taxa.
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the mitochondrial and chloroplast genomes of the Haptophyte chrysochromulina tobin contain unique repeat structures and gene profiles
BMC Genomics, 2014Co-Authors: Blake T. Hovde, Heather M Hunsperger, Chloe R. Deodato, Ramesh K. Jha, Raymond J. Monnat, Shawn R. Starkenburg, Olga Chertkov, Laina D Mercer, Rose Ann CattolicoAbstract:Haptophytes are widely and abundantly distributed in both marine and freshwater ecosystems. Few genomic analyses of representatives within this taxon have been reported, despite their early evolutionary origins and their prominent role in global carbon fixation. The complete mitochondrial and chloroplast genome sequences of the Haptophyte Chrysochromulina tobin (Prymnesiales) provide insight into the architecture and gene content of Haptophyte organellar genomes. The mitochondrial genome (~34 kb) encodes 21 protein coding genes and contains a complex, 9 kb tandem repeat region. Similar to other Haptophytes and rhodophytes, but not cryptophytes or stramenopiles, the mitochondrial genome has lost the nad7, nad9 and nad11 genes. The ~105 kb chloroplast genome encodes 112 protein coding genes, including ycf39 which has strong structural homology to NADP-binding nitrate transcriptional regulators; a divergent ‘CheY-like’ two-component response regulator (ycf55) and Tic/Toc (ycf60 and ycf80) membrane transporters. Notably, a zinc finger domain has been identified in the rpl36 ribosomal protein gene of all chloroplasts sequenced to date with the exception of Haptophytes and cryptophytes - algae that have gained (via lateral gene transfer) an alternative rpl36 lacking the zinc finger motif. The two C. tobin chloroplast ribosomal RNA operon spacer regions differ in tRNA content. Additionally, each ribosomal operon contains multiple single nucleotide polymorphisms (SNPs) - a pattern observed in rhodophytes and cryptophytes, but few stramenopiles. Analysis of small (<200 bp) chloroplast encoded tandem and inverted repeats in C. tobin and 78 other algal chloroplast genomes show that repeat type, size and location are correlated with gene identity and taxonomic clade. The Chrysochromulina tobin organellar genomes provide new insight into organellar function and evolution. These are the first organellar genomes to be determined for the prymnesiales, a taxon that is present in both oceanic and freshwater systems and represents major primary photosynthetic producers and contributors to global ecosystem stability.
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The mitochondrial and chloroplast genomes of the Haptophyte Chrysochromulina tobin contain unique repeat structures and gene profiles
BMC genomics, 2014Co-Authors: Blake T. Hovde, Heather M Hunsperger, Chloe R. Deodato, Ramesh K. Jha, Raymond J. Monnat, Shawn R. Starkenburg, Olga Chertkov, Laina D Mercer, Rose Ann CattolicoAbstract:Haptophytes are widely and abundantly distributed in both marine and freshwater ecosystems. Few genomic analyses of representatives within this taxon have been reported, despite their early evolutionary origins and their prominent role in global carbon fixation. The complete mitochondrial and chloroplast genome sequences of the Haptophyte Chrysochromulina tobin (Prymnesiales) provide insight into the architecture and gene content of Haptophyte organellar genomes. The mitochondrial genome (~34 kb) encodes 21 protein coding genes and contains a complex, 9 kb tandem repeat region. Similar to other Haptophytes and rhodophytes, but not cryptophytes or stramenopiles, the mitochondrial genome has lost the nad7, nad9 and nad11 genes. The ~105 kb chloroplast genome encodes 112 protein coding genes, including ycf39 which has strong structural homology to NADP-binding nitrate transcriptional regulators; a divergent ‘CheY-like’ two-component response regulator (ycf55) and Tic/Toc (ycf60 and ycf80) membrane transporters. Notably, a zinc finger domain has been identified in the rpl36 ribosomal protein gene of all chloroplasts sequenced to date with the exception of Haptophytes and cryptophytes - algae that have gained (via lateral gene transfer) an alternative rpl36 lacking the zinc finger motif. The two C. tobin chloroplast ribosomal RNA operon spacer regions differ in tRNA content. Additionally, each ribosomal operon contains multiple single nucleotide polymorphisms (SNPs) - a pattern observed in rhodophytes and cryptophytes, but few stramenopiles. Analysis of small (
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The mitochondrial and chloroplast genomes of the Haptophyte Chrysochromulina tobin contain unique repeat structures and gene profiles
BMC Genomics, 2014Co-Authors: Blake T. Hovde, Heather M Hunsperger, Chloe R. Deodato, Ramesh K. Jha, Raymond J. Monnat, Shawn R. Starkenburg, Olga Chertkov, Laina D Mercer, Rose Ann CattolicoAbstract:Background Haptophytes are widely and abundantly distributed in both marine and freshwater ecosystems. Few genomic analyses of representatives within this taxon have been reported, despite their early evolutionary origins and their prominent role in global carbon fixation. Results The complete mitochondrial and chloroplast genome sequences of the Haptophyte Chrysochromulina tobin (Prymnesiales) provide insight into the architecture and gene content of Haptophyte organellar genomes. The mitochondrial genome (~34 kb) encodes 21 protein coding genes and contains a complex, 9 kb tandem repeat region. Similar to other Haptophytes and rhodophytes, but not cryptophytes or stramenopiles, the mitochondrial genome has lost the nad 7, nad 9 and nad 11 genes. The ~105 kb chloroplast genome encodes 112 protein coding genes, including ycf 39 which has strong structural homology to NADP-binding nitrate transcriptional regulators; a divergent ‘CheY-like’ two-component response regulator ( ycf 55) and Tic/Toc ( ycf 60 and ycf 80) membrane transporters. Notably, a zinc finger domain has been identified in the rpl 36 ribosomal protein gene of all chloroplasts sequenced to date with the exception of Haptophytes and cryptophytes - algae that have gained (via lateral gene transfer) an alternative rpl 36 lacking the zinc finger motif. The two C. tobin chloroplast ribosomal RNA operon spacer regions differ in tRNA content. Additionally, each ribosomal operon contains multiple single nucleotide polymorphisms (SNPs) - a pattern observed in rhodophytes and cryptophytes, but few stramenopiles. Analysis of small (
Stefan Schouten - One of the best experts on this subject based on the ideXlab platform.
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Impact of metabolic pathways and salinity on the hydrogen isotope ratios of Haptophyte lipids
2019Co-Authors: Gabriella M. Weiss, Stefan Schouten, Jaap S. Sinninghe Damsté, Sebastian Kasper, David Chivall, Hideto Nakamura, Fiz Da Costa, Philippe Soudant, Marcel T. J. Van Der MeerAbstract:Abstract. Hydrogen isotope ratios of biomarkers have been shown to reflect water isotope ratios, and in some cases correlate significantly with salinity. The δ2H-salinity relationship is best studied for long-chain alkenones, biomarkers for Haptophyte algae, and is known to be influenced by a number of different environmental parameters. It is not fully known why δ2H ratios of lipids retain a correlation to salinity, and whether this is a general feature for other lipids produced by Haptophyte algae. Here, we analyzed δ2H ratios of three fatty acids, brassicasterol, long-chain C37 alkenones and phytol from three different Haptophyte species grown over a range of salinities. Lipids synthesized in the cytosol, or relying on precursors of cytosolic origin, show a correlation between their δ2H ratios and salinity. In contrast, biosynthesis in the chloroplast, or utilizing precursors created in the chloroplast, yields lipids that do not show a correlation between δ2H ratios and salinity. This leads to the conclusion that location of metabolism is the first-order control on the salinity signal retained in δ2H ratios of certain lipids. Additionally, we found that δ2H ratios of alkenones from batch cultures of the Group II Haptophyte species Tisochrysis lutea correlate positively with temperature, contrary to findings from cultures of Group III Haptophytes, but retain a similar response to nutrient availability in line with other Group III Haptophytes.
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testing the alkenone d h ratio as a paleo indicator of sea surface salinity in a coastal ocean margin mozambique channel
Organic Geochemistry, 2015Co-Authors: Sebastian Kasper, M.t.j. Van Der Meer, Isla S. Castañeda, Rik Tjallingii, Geertjan A Brummer, J Sinninghe S Damste, Stefan SchoutenAbstract:Abstract Reconstructing past ocean salinity is important for assessing paleoceanographic change and therefore past climatic dynamics. Commonly, sea water salinity reconstruction is based on planktonic foraminifera oxygen isotope values combined with sea surface temperature reconstruction. However, the approach relies on multiple proxies, resulting in rather large uncertainty and, consequently, relatively low accuracy of salinity estimates. An alternative tool for past ocean salinity reconstruction is the hydrogen isotope composition of long chain (C37) alkenones (δDalkenone). Here, we have applied δDalkenone to a 39 ka sedimentary record from the Eastern South African continental shelf in the Mozambique Channel, close to the Zambezi River mouth. Despite changes in global seawater δD related to glacial – interglacial ice volume effects, no clear changes were observed in the δDalkenone record throughout the entire 39 ka. The BIT index record from the same core, which provides information on relative contributions of soil organic matter (OM) vs. marine input, indicates high soil OM input during the glacial and low input during the Holocene. This suggests a more pronounced freshwater influence at the core location during the glacial, resulting in alkenones depleted in D during that time, thereby explaining the lack of a clear glacial-interglacial alkenone δD shift. The correlation between the BIT index and δDalkenone during the glacial period suggests that increased continental runoff potentially changed the growth conditions of the alkenone-producing Haptophytes, promoting coastal Haptophyte species with generally more enriched δDalkenone values. We therefore suggest that the application of δDalkenone for reconstructing past salinity in coastal settings may be complicated by changes in the alkenone-producing Haptophyte community.
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the effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal Haptophyte algae
Geochimica et Cosmochimica Acta, 2014Co-Authors: David Chivall, Stefan Schouten, Jaap Sinninghe S Damste, Daniela Mboule, Danielle Sinkeschoen, Marcel T. J. Van Der MeerAbstract:The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine Haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity has previously only been determined during exponential growth, whilst it is not yet known in which growth phases natural Haptophyte populations predominantly exist. We have therefore determined the relationship between the fractionation factor, αalkenones-water, and salinity for C37 alkenones produced in different growth phases of batch cultures of the major alkenone-producing coastal Haptophytes Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) over a range in salinity from ca. 10 to 35. αalkenones-water was similar in both species, ranging over 0.841-0.900 for I. galbana and 0.838-0.865 for C. lamellosa. A strong (0.85≤R2≤0.97; p<0.0001) relationship between salinity and fractionation factor was observed in both species at all growth phases investigated. This suggests that alkenone δD has the potential to be used as a salinity proxy in neritic areas where Haptophyte communities are dominated by these coastal species. However, there was a marked difference in the sensitivity of αalkenones-water to salinity between different growth phases: in the exponential growth phase of I. galbana, αalkenones-water increased by 0.0019 per salinity unit (S-1), but was less sensitive at 0.0010 and 0.0008S-1 during the stationary and decline phases, respectively. Similarly, in C. lamellosa αalkenones-water increased by 0.0010S-1 in the early stationary phase and by 0.0008S-1 during the late stationary phase. Assuming the shift in sensitivity of αalkenones-water to salinity observed at the end of exponential growth in I. galbana is similar in other alkenone-producing species, the predominant growth phase of natural populations of Haptophytes will affect the sensitivity of the alkenone salinity proxy. The proxy is likely to be most sensitive to salinity when alkenones are produced in a state similar to exponential growth. © 2014 Elsevier Ltd.
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The effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal Haptophyte algae
Geochimica et Cosmochimica Acta, 2014Co-Authors: David Chivall, Stefan Schouten, Jaap S. Sinninghe Damsté, Daniela M'boule, Daniëlle Sinke-schoen, Marcel T. J. Van Der MeerAbstract:The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine Haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity has previously only been determined during exponential growth, whilst it is not yet known in which growth phases natural Haptophyte populations predominantly exist. We have therefore determined the relationship between the fractionation factor, αalkenones-water, and salinity for C37 alkenones produced in different growth phases of batch cultures of the major alkenone-producing coastal Haptophytes Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) over a range in salinity from ca. 10 to 35. αalkenones-water was similar in both species, ranging over 0.841-0.900 for I. galbana and 0.838-0.865 for C. lamellosa. A strong (0.85≤R2≤0.97; p
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Salinity dependent hydrogen isotope fractionation in alkenones produced by coastal and open ocean Haptophyte algae
Geochimica et Cosmochimica Acta, 2014Co-Authors: Daniela M'boule, Stefan Schouten, Jaap S. Sinninghe Damsté, David Chivall, Daniëlle Sinke-schoen, Marcel T. J. Van Der MeerAbstract:Abstract The hydrogen isotope fractionation in alkenones produced by Haptophyte algae is a promising new proxy for paleosalinity reconstructions. To constrain and further develop this proxy the coastal Haptophyte Isochrysis galbana and the open ocean Haptophyte alga Emiliania huxleyi were cultured at different salinities. The fractionation factor, αalkenones–water, ranged between 0.853 and 0.902 for I. galbana and 0.789 and 0.822 for E. huxleyi. The results show a strong linear correlation between the fractionation factor α and salinity for E. huxleyi, in agreement with earlier studies, but also for I. galbana. Both Haptophytes show the same response to changes in salinity, represented by the slopes of the α–salinity relationship (∼0.002 per salinity unit). This suggests that the same process, in both coastal as well as open ocean Haptophytes, is responsible for reducing fractionation with increasing salinity. However, there is a significant difference in absolute isotope fractionation between E. huxleyi and I. galbana, i.e. E. huxleyi produces alkenones which are 90‰ more depleted in D under the same culturing conditions than I. galbana. Our data suggest that the δD of alkenones can be used to reconstruct relative shifts in paleosalinity in coastal as well as open ocean environments with careful consideration of species composition and other complicating factors especially in coastal regions.
Yongsong Huang - One of the best experts on this subject based on the ideXlab platform.
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Successional blooms of alkenone-producing Haptophytes in Lake George, North Dakota: Implications for continental paleoclimate reconstructions
Limnology and Oceanography, 2019Co-Authors: Susanna Theroux, Yongsong Huang, Jaime L. Toney, Robert A. Andersen, Paul Nyren, Rick Bohn, Jeffrey M. Salacup, Leslie G. Murphy, Linda Amaral-zettlerAbstract:Alkenone‐derived paleotemperature reconstruction holds great promise in lake environments. However, the occurrence of multiple species of alkenone‐producing Haptophyte algae in a single lake can complicate the translation of alkenone unsaturation to temperature if each species requires an individual temperature calibration. Here, we present the first systematic monitoring of two alkenone‐producing Haptophytes throughout the course of a seasonal cycle in Lake George, North Dakota, using a combined approach of DNA sequencing and alkenone lipid characterization. Field sampling revealed a nonoverlapping Haptophyte succession, with both an early and late season Haptophyte bloom event. Culturing experiments demonstrated that the two Haptophyte species responsible for these blooms had statistically similar alkenone‐temperature responses, although the culture‐based calibrations were distinct from the in situ calibration. Bloom timing of each Haptophyte species corresponded to surface‐water temperatures that differed by more than 10°C, revealing that changes in bloom intensities for each species will skew the sediment‐inferred temperatures to a different stage of the growth season. These results highlight the importance of accounting for bloom timing when interpreting alkenone‐derived temperatures in sediment cores, especially in lakes that experience large seasonal fluctuations in water column temperature and salinity.
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systematic chemotaxonomic profiling and novel paleotemperature indices based on alkenones and alkenoates potential for disentangling mixed species input
Organic Geochemistry, 2019Co-Authors: Maureen H Conte, Yinsui Zheng, Patrick Heng, Richard S Vachula, Yongsong HuangAbstract:Abstract The unsaturation indices ( U 37 K , U 37 K' ) of long chain alkenones are powerful paleotemperature proxies and have been widely applied for sea surface temperature (SST) reconstructions in the past three decades. However, these indices encounter major difficulties in systems harboring different alkenone-producing Haptophyte species, such as saline lakes and marginal ocean environments. All Haptophytes produce C37 alkenones, but different species often display large differences in temperature calibrations and may bloom in different seasons, hindering the use of U 37 K and U 37 K' indices for reliable paleotemperature reconstructions in mixed systems. To overcome these problems, we have recently reported a new analytical method that allows comprehensive separation of up to 32 alkenones, alkenoates and their double bond positional isomers in culture and sediment samples. Here we report a systematic analysis of alkenones and alkenoates from six Haptophyte cultures growing at a wide range of temperatures (4–25 °C). Together with a compilation of 230 previously published culture data sets, we present here systematic calibrations of temperature-sensitive indices based on all alkenone and alkenoate homologues (including isomers). Using this dataset, we extract systematic chemotaxonomic criteria for differentiating individual Haptophyte species and demonstrate such chemotaxonomic features can be encoded into a machine learning model for reliable species identifications. Specifically, we show that temperature calibrations based on C38 methyl ketones and C39 ethyl ketones are potentially useful for disentangling mixed inputs in estuarine systems where Group III (E. huxleyi) and Group II alkenones mix, and that C36 ethyl alkenoate isomeric ratios display minimal species heterogeneity and are potentially more suited for reconstructing temperatures in mixed systems with different Group II Haptophytes. Using the culture data as base profiles, we construct a mathematical model for estimating percentage inputs from alkenones of different Isochrysidales groups in mixed systems, with potential implications for inferring past salinity changes. Overall, the results from this study demonstrate important new applications of alkenone and alkenoate biomarkers in paleoclimate and paleoenvironmental research.
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Comparative molecular microbial ecology of the spring Haptophyte bloom in a greenland arctic oligosaline lake.
Frontiers in microbiology, 2012Co-Authors: Susanna Theroux, Yongsong Huang, Linda A. Amaral-zettlerAbstract:The Arctic is highly sensitive to increasing global temperatures and is projected to experience dramatic ecological shifts in the next few decades. Oligosaline lakes are common in arctic regions where evaporation surpasses precipitation, however these extreme microbial communities are poorly characterized. Many oligosaline lakes, in contrast to freshwater ones, experience annual blooms of Haptophyte algae that generate valuable alkenone biomarker records that can be used for paleoclimate reconstruction. These Haptophyte algae are globally important, and globally distributed, aquatic phototrophs yet their presence in microbial molecular surveys is scarce. To target Haptophytes in a molecular survey, we compared microbial community structure during two Haptophyte bloom events in an arctic oligosaline lake, Lake BrayaSo in southwestern Greenland, using high-throughput pyrotag sequencing. Our comparison of two annual bloom events yielded surprisingly low taxon overlap, only 13% for bacterial and 26% for eukaryotic communities, which indicates significant annual variation in the underlying microbial populations. Both the bacterial and eukaryotic communities strongly resembled high-altitude and high-latitude freshwater environments. In spite of high alkenone concentrations in the water column, and corresponding high Haptophyte rRNA gene copy numbers, Haptophyte pyrotag sequences were not the most abundant eukaryotic tag, suggesting that sequencing biases obscured relative abundance data. With over 170 Haptophyte tag sequences, we observed only one Haptophyte algal Operational Taxonomic Unit, a prerequisite for accurate paleoclimate reconstruction from the lake sediments. Our study is the first to examine microbial diversity in a Greenland lake using next generation sequencing and the first to target an extreme Haptophyte bloom event. Our results provide a context for future explorations of aquatic ecology in the warming arctic.
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Culturing of the first 37:4 predominant lacustrine Haptophyte: Geochemical, biochemical, and genetic implications
Geochimica et Cosmochimica Acta, 2012Co-Authors: Jaime L. Toney, Susanna Theroux, Robert A. Andersen, Linda A. Amaral-zettler, Annette W. Coleman, Yongsong HuangAbstract:Long chain alkenones (LCAs) are potential biomarkers for quantitative paleotemperature reconstructions from lacustrine environments. However, progress in this area has been hindered, because the conditions necessary for the growth of Haptophytes responsible for alkenone distributions in lake sediments: the predominance of C37:4 LCA are not known. Here we report the first enrichment culturing of a novel Haptophyte phylotype (Hap-A) from Lake George, ND that produces predominantly C37:4-LCA. Hap-A was enriched from its resting phase collected from deep sediments rather than from water column samples. In contrast, enrichments from near surface water yielded a different Haptophyte phylotype (Hap-B), closely related to Chrysotila lamellosa and Pseudoisochrysis paradoxa, which does not display C37:4-LCA predominance (similar enrichments have been reported previously). The LCA profile in sediments resembles that of enrichments containing Hap-A, suggesting that Hap-A is the dominant alkenone producer of the sedimentary LCAs. In enrichments, increased lighting appeared to be crucial for triggering alkenone production. Both U37K and U38K indices show a promising, positive relationship with temperature for Hap-A in enrichments, but the offset from the environmental calibration suggests that other factors (e.g., the growth stage or nutrients) may influence the absolute U37K value. Based on 18S rRNA gene analyses, several lakes from the Northern Great Plains, as well as Pyramid Lake, NV and Tso Ur, Tibetan Plateau, China contain the same two Haptophyte phylotypes. Analysis of surface sediment from the Great Plains lakes show the Hap-A-type LCA distribution, whereas Pyramid and Tso Ur show the Hap-B type distribution. Waters of the Great Plain lakes are dominated by sulfate ions, whereas those Pyramid and Tso Ur are dominated by carbonate ions, suggesting that the sulfate to carbonate ratio may be a determining factor for the dominance of the Hap-A and Hap-B phylotypes in natural settings.
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phylogenetic diversity and evolutionary relatedness of alkenone producing Haptophyte algae in lakes implications for continental paleotemperature reconstructions
Earth and Planetary Science Letters, 2010Co-Authors: Jaime L. Toney, Susanna Theroux, William J Dandrea, Linda A Amaralzettler, Yongsong HuangAbstract:Alkenones have been found in an increasing number of lakes around the world, making them a promising new tool for continental paleoclimate reconstruction. However, individual lakes may harbor different species of Haptophyte algae with different sensitivities to temperature variations, thus presenting a significant challenge to the use of lacustrine alkenones for paleotemperature reconstructions. To explore the extent of lacustrine Haptophyte diversity, we conducted the first comprehensive phylogenetic and geochemical survey of lacustrine alkenone producers. We sampled 15 alkenone-containing lake surface sediments from a variety of geographic locales and inferred identities of environmental sequences using 18S ribosomal RNA (rRNA) gene-based phylogenies. For two lakes, BrayaSo in southwest Greenland and Tso Ur on the Tibetan Plateau, we also analyzed both surface and downcore sediments to characterize Haptophyte populations through time. In parallel with phylogenetic analyses, we determined the alkenone distributions (including C37/C38 ratios, and the presence/absence of C38 methyl ketones and C40 compounds) in all the samples. The resulting alkenone profiles from this study do not all align with traditional “marine” versus “coastal/lacustrine” alkenone profiles. Additionally, our genetic data indicate the presence of multiple Haptophyte species from a single lake sediment sample; these distinct Haptophyte populations could not be discerned from the alkenone profiles alone. These results show that alkenone profiles are not a reliable way to assess the Haptophyte algae in lakes and that DNA fingerprinting is a preferred approach for species identification. Although closely related Haptophyte species or subspecies may not warrant different temperature calibrations, our results emphasize the importance of genetic data for inferring Haptophyte identities and eventually selecting alkenone–temperature calibrations for paleoclimate reconstructions.
