The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform
Shawn R. Starkenburg - One of the best experts on this subject based on the ideXlab platform.
-
RESEARCH ARTICLE Genome Sequence and Transcriptome Analyses of Chrysochromulina tobin: Metabolic Tools for Enhanced Algal Fitness in the Prominent Order Prymnesiales (Haptophyceae)
2016Co-Authors: Blake T. Hovde, Heather M Hunsperger, Chloe R. Deodato, Scott A. Ryken, Will Yost, Ramesh K. Jha, Johnathan Patterson, Raymond J. Monnat, B. Barlow, Shawn R. StarkenburgAbstract:Haptophytes are recognized as seminal players in aquatic ecosystem function. These algae are important in global carbon sequestration, form destructive harmful blooms, and given their rich fatty acid content, serve as a highly nutritive food source to a broad range of eco-cohorts. Haptophyte dominance in both fresh and marine waters is supported by the mixotrophic nature of many taxa. Despite their importance the nuclear genome sequence of only one haptophyte, Emiliania huxleyi (Isochrysidales), is available. Here we report the draft genome sequence of Chrysochromulina tobin (Prymnesiales), and transcriptome data collected at seven time points over a 24-hour light/dark cycle. The nuclear genome of C. tobin is small (59 Mb), compact (*40 % of the genome is protein coding) and encodes approximately 16,777 genes. Genes important to fatty acid synthesis, modification, and catabolism show distinct patterns of expression when monitored over the circadian photo-period. The C. tobin genome harbors the first hybrid polyketide synthase/non-ribosomal peptide synthase gene complex reported for an algal species, and encodes potential anti-microbial peptides and proteins involved in multidrug and toxic compound extrusion. A ne
-
Genome Sequence and Transcriptome Analyses of Chrysochromulina tobin: Metabolic Tools for Enhanced Algal Fitness in the Prominent Order Prymnesiales (Haptophyceae)
PLoS genetics, 2015Co-Authors: Blake T. Hovde, Heather M Hunsperger, Chloe R. Deodato, Scott A. Ryken, Will Yost, Ramesh K. Jha, Johnathan Patterson, Raymond J. Monnat, Steven B. Barlow, Shawn R. StarkenburgAbstract:Haptophytes are recognized as seminal players in aquatic ecosystem function. These algae are important in global carbon sequestration, form destructive harmful blooms, and given their rich fatty acid content, serve as a highly nutritive food source to a broad range of eco-cohorts. Haptophyte dominance in both fresh and marine waters is supported by the mixotrophic nature of many taxa. Despite their importance the nuclear genome sequence of only one haptophyte, Emiliania huxleyi (Isochrysidales), is available. Here we report the draft genome sequence of Chrysochromulina tobin (Prymnesiales), and transcriptome data collected at seven time points over a 24-hour light/dark cycle. The nuclear genome of C. tobin is small (59 Mb), compact (∼40% of the genome is protein coding) and encodes approximately 16,777 genes. Genes important to fatty acid synthesis, modification, and catabolism show distinct patterns of expression when monitored over the circadian photoperiod. The C. tobin genome harbors the first hybrid polyketide synthase/non-ribosomal peptide synthase gene complex reported for an algal species, and encodes potential anti-microbial peptides and proteins involved in multidrug and toxic compound extrusion. A new haptophyte xanthorhodopsin was also identified, together with two “red” RuBisCO activases that are shared across many algal lineages. The Chrysochromulina tobin genome sequence provides new information on the evolutionary history, ecology and economic importance of haptophytes.
-
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.
Blake T. Hovde - One of the best experts on this subject based on the ideXlab platform.
-
RESEARCH ARTICLE Genome Sequence and Transcriptome Analyses of Chrysochromulina tobin: Metabolic Tools for Enhanced Algal Fitness in the Prominent Order Prymnesiales (Haptophyceae)
2016Co-Authors: Blake T. Hovde, Heather M Hunsperger, Chloe R. Deodato, Scott A. Ryken, Will Yost, Ramesh K. Jha, Johnathan Patterson, Raymond J. Monnat, B. Barlow, Shawn R. StarkenburgAbstract:Haptophytes are recognized as seminal players in aquatic ecosystem function. These algae are important in global carbon sequestration, form destructive harmful blooms, and given their rich fatty acid content, serve as a highly nutritive food source to a broad range of eco-cohorts. Haptophyte dominance in both fresh and marine waters is supported by the mixotrophic nature of many taxa. Despite their importance the nuclear genome sequence of only one haptophyte, Emiliania huxleyi (Isochrysidales), is available. Here we report the draft genome sequence of Chrysochromulina tobin (Prymnesiales), and transcriptome data collected at seven time points over a 24-hour light/dark cycle. The nuclear genome of C. tobin is small (59 Mb), compact (*40 % of the genome is protein coding) and encodes approximately 16,777 genes. Genes important to fatty acid synthesis, modification, and catabolism show distinct patterns of expression when monitored over the circadian photo-period. The C. tobin genome harbors the first hybrid polyketide synthase/non-ribosomal peptide synthase gene complex reported for an algal species, and encodes potential anti-microbial peptides and proteins involved in multidrug and toxic compound extrusion. A ne
-
Genome Sequence and Transcriptome Analyses of Chrysochromulina tobin: Metabolic Tools for Enhanced Algal Fitness in the Prominent Order Prymnesiales (Haptophyceae)
PLoS genetics, 2015Co-Authors: Blake T. Hovde, Heather M Hunsperger, Chloe R. Deodato, Scott A. Ryken, Will Yost, Ramesh K. Jha, Johnathan Patterson, Raymond J. Monnat, Steven B. Barlow, Shawn R. StarkenburgAbstract:Haptophytes are recognized as seminal players in aquatic ecosystem function. These algae are important in global carbon sequestration, form destructive harmful blooms, and given their rich fatty acid content, serve as a highly nutritive food source to a broad range of eco-cohorts. Haptophyte dominance in both fresh and marine waters is supported by the mixotrophic nature of many taxa. Despite their importance the nuclear genome sequence of only one haptophyte, Emiliania huxleyi (Isochrysidales), is available. Here we report the draft genome sequence of Chrysochromulina tobin (Prymnesiales), and transcriptome data collected at seven time points over a 24-hour light/dark cycle. The nuclear genome of C. tobin is small (59 Mb), compact (∼40% of the genome is protein coding) and encodes approximately 16,777 genes. Genes important to fatty acid synthesis, modification, and catabolism show distinct patterns of expression when monitored over the circadian photoperiod. The C. tobin genome harbors the first hybrid polyketide synthase/non-ribosomal peptide synthase gene complex reported for an algal species, and encodes potential anti-microbial peptides and proteins involved in multidrug and toxic compound extrusion. A new haptophyte xanthorhodopsin was also identified, together with two “red” RuBisCO activases that are shared across many algal lineages. The Chrysochromulina tobin genome sequence provides new information on the evolutionary history, ecology and economic importance of haptophytes.
-
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.
Ulf Larsson - One of the best experts on this subject based on the ideXlab platform.
-
in depth analysis of an alternate stage prymnesium polylepis haptophyta bloom and long term trends in abundance of Prymnesiales species in the baltic sea
Marine Ecology Progress Series, 2015Co-Authors: Susanna Hajdu, Elena Gorokhova, Ulf LarssonAbstract:In late autumn/winter 2007, high abundances of the alternate-stage Prymnesium polylepis were observed in many Baltic Sea areas, attaining bloom concentrations in spring 2008. To understand long-term variability in Prymnesiales density, we analysed changes in the abundance of different size classes of Prymnesiales using a long-term time series (1985-2008) for an inshore-offshore gradient in the northern Baltic proper. Further, to understand environmental conditions contributing to the P. polylepis bloom, we examined environmental factors associated with the increase in Prymnesiales abundances by placing the bloom dynamics within the context of temporal and spatial environmental variability over the last decades in the Baltic Sea. Significantly increasing abundances were found for larger size classes of Prymnesiales (6-10 mu m and >10 mu m) but not for the smaller species (Prymnesiales 10 mu m) that tolerate low annual NO2+NO3 concentrations. Thus, long-term trends in increase in abundance, as well as changes in the relative contributions of species within these potentially toxic haptophytes, are likely to be the result of interacting changes in temperature and nutrient conditions since the late 1980s.
-
Responses of phyto- and zooplankton communities to Prymnesium polylepis (Prymnesiales) bloom in the Baltic Sea.
PloS one, 2014Co-Authors: Elena Gorokhova, Susanna Hajdu, Ulf LarssonAbstract:A large bloom of Prymnesium polylepis occurred in the Baltic Sea during the winter 2007 - spring 2008. Based on numerous reports of strong allelopathic effects on phytoplankton exerted by P. polylepis and its toxicity to grazers, we hypothesized that during this period negative correlations will be observed between P. polylepis and (1) main phytoplankton groups contributing to the spring bloom (i.e., diatoms and dinoflagellates), and (2) zooplankton growth and abundance. To test these hypotheses, we analyzed inter-annual variability in phytoplankton and zooplankton dynamics as well as growth indices (RNA: DNA ratio) in dominant zooplankton in relation to the Prymnesium abundance and biomass. Contrary to the hypothesized relationships, no measurable negative responses to P. polylepis were observed for either the total phytoplankton stocks or the zooplankton community. The only negative response, possibly associated with P. polylepis occurrence, was significantly lower abundance of dinoflagellates both during and after the bloom in 2008. Moreover, contrary to the expected negative effects, there were significantly higher total phytoplankton abundance as well as significantly higher winter abundance and winter-spring RNA: DNA ratio in dominant zooplankton species in 2008, indicating that P. polylepis bloom coincided with favourable feeding conditions for zooplankton. Thus, primary consumers, and consequently also zooplanktivores (e.g., larval fish and mysids), may benefit from haptophyte blooms, particularly in winter, when phytoplankton is scarce.
-
Generalized linear model for zooplankton growth indices as a function of abiotic (monthly NAO, SST, and salinity) and biotic (total phytoplankton biomass [TPhyto], biomass and contribution of Prymnesiales [P and %P, respectively], biomass and contribution of P. polylepis to TPhyto [Pp and %Pp, respectively] and phytoplankton biomass excluding Prymnesiales [otherPhyto]) variables in winter-spring (Dec–May) and summer-autumn (Jun–Nov) during 2007–2008; see Methods for details on data origin and time coverage.
2014Co-Authors: Elena Gorokhova, Susanna Hajdu, Ulf LarssonAbstract:Significant effects are in bold face.Generalized linear model for zooplankton growth indices as a function of abiotic (monthly NAO, SST, and salinity) and biotic (total phytoplankton biomass [TPhyto], biomass and contribution of Prymnesiales [P and %P, respectively], biomass and contribution of P. polylepis to TPhyto [Pp and %Pp, respectively] and phytoplankton biomass excluding Prymnesiales [otherPhyto]) variables in winter-spring (Dec–May) and summer-autumn (Jun–Nov) during 2007–2008; see Methods for details on data origin and time coverage.
-
Differences in phytoplankton biovolumes (mm3 L−1) in January-June between the year 2008 and 2007.
2014Co-Authors: Elena Gorokhova, Susanna Hajdu, Ulf LarssonAbstract:Abbreviations: DIAT - Diatoms, DINO - Dinoflagellates, PRYM - Prymnesiales. Stations are ordered south to north.
Susanna Hajdu - One of the best experts on this subject based on the ideXlab platform.
-
in depth analysis of an alternate stage prymnesium polylepis haptophyta bloom and long term trends in abundance of Prymnesiales species in the baltic sea
Marine Ecology Progress Series, 2015Co-Authors: Susanna Hajdu, Elena Gorokhova, Ulf LarssonAbstract:In late autumn/winter 2007, high abundances of the alternate-stage Prymnesium polylepis were observed in many Baltic Sea areas, attaining bloom concentrations in spring 2008. To understand long-term variability in Prymnesiales density, we analysed changes in the abundance of different size classes of Prymnesiales using a long-term time series (1985-2008) for an inshore-offshore gradient in the northern Baltic proper. Further, to understand environmental conditions contributing to the P. polylepis bloom, we examined environmental factors associated with the increase in Prymnesiales abundances by placing the bloom dynamics within the context of temporal and spatial environmental variability over the last decades in the Baltic Sea. Significantly increasing abundances were found for larger size classes of Prymnesiales (6-10 mu m and >10 mu m) but not for the smaller species (Prymnesiales 10 mu m) that tolerate low annual NO2+NO3 concentrations. Thus, long-term trends in increase in abundance, as well as changes in the relative contributions of species within these potentially toxic haptophytes, are likely to be the result of interacting changes in temperature and nutrient conditions since the late 1980s.
-
Responses of phyto- and zooplankton communities to Prymnesium polylepis (Prymnesiales) bloom in the Baltic Sea.
PloS one, 2014Co-Authors: Elena Gorokhova, Susanna Hajdu, Ulf LarssonAbstract:A large bloom of Prymnesium polylepis occurred in the Baltic Sea during the winter 2007 - spring 2008. Based on numerous reports of strong allelopathic effects on phytoplankton exerted by P. polylepis and its toxicity to grazers, we hypothesized that during this period negative correlations will be observed between P. polylepis and (1) main phytoplankton groups contributing to the spring bloom (i.e., diatoms and dinoflagellates), and (2) zooplankton growth and abundance. To test these hypotheses, we analyzed inter-annual variability in phytoplankton and zooplankton dynamics as well as growth indices (RNA: DNA ratio) in dominant zooplankton in relation to the Prymnesium abundance and biomass. Contrary to the hypothesized relationships, no measurable negative responses to P. polylepis were observed for either the total phytoplankton stocks or the zooplankton community. The only negative response, possibly associated with P. polylepis occurrence, was significantly lower abundance of dinoflagellates both during and after the bloom in 2008. Moreover, contrary to the expected negative effects, there were significantly higher total phytoplankton abundance as well as significantly higher winter abundance and winter-spring RNA: DNA ratio in dominant zooplankton species in 2008, indicating that P. polylepis bloom coincided with favourable feeding conditions for zooplankton. Thus, primary consumers, and consequently also zooplanktivores (e.g., larval fish and mysids), may benefit from haptophyte blooms, particularly in winter, when phytoplankton is scarce.
-
Generalized linear model for zooplankton growth indices as a function of abiotic (monthly NAO, SST, and salinity) and biotic (total phytoplankton biomass [TPhyto], biomass and contribution of Prymnesiales [P and %P, respectively], biomass and contribution of P. polylepis to TPhyto [Pp and %Pp, respectively] and phytoplankton biomass excluding Prymnesiales [otherPhyto]) variables in winter-spring (Dec–May) and summer-autumn (Jun–Nov) during 2007–2008; see Methods for details on data origin and time coverage.
2014Co-Authors: Elena Gorokhova, Susanna Hajdu, Ulf LarssonAbstract:Significant effects are in bold face.Generalized linear model for zooplankton growth indices as a function of abiotic (monthly NAO, SST, and salinity) and biotic (total phytoplankton biomass [TPhyto], biomass and contribution of Prymnesiales [P and %P, respectively], biomass and contribution of P. polylepis to TPhyto [Pp and %Pp, respectively] and phytoplankton biomass excluding Prymnesiales [otherPhyto]) variables in winter-spring (Dec–May) and summer-autumn (Jun–Nov) during 2007–2008; see Methods for details on data origin and time coverage.
-
Differences in phytoplankton biovolumes (mm3 L−1) in January-June between the year 2008 and 2007.
2014Co-Authors: Elena Gorokhova, Susanna Hajdu, Ulf LarssonAbstract:Abbreviations: DIAT - Diatoms, DINO - Dinoflagellates, PRYM - Prymnesiales. Stations are ordered south to north.
-
The extensive bloom of alternate-stage Prymnesium polylepis (Haptophyta) in the Baltic Sea during autumn-spring 2007-2008.
European Journal of Phycology, 2012Co-Authors: Markus Majaneva, Janne-markus Rintala, Susanna Hajdu, Seija Hällfors, Guy Hällfors, Ann-turi Skjevik, Slawomira Gromisz, Janina Kownacka, Susanne Busch, Jaanika BlomsterAbstract:During autumn 2007, an unusual increase in an algal species belonging to the order Prymnesiales was observed throughout the Baltic Sea Proper during routine national monitoring. Electron microscopical examination of the blooming species showed two types of flat scales – small and large – that resembled those of the alternate stage of Prymnesium polylepis. No spine-bearing scales were found. The 18S rDNA sequence data (n = 20, c. 1500 bp) verified the species identification as P. polylepis. There was up to 0.5% (7 bp) variability in the P. polylepis partial 18 S rDNA sequences from the Baltic Sea. These environmental sequences differed by 0–0.35% (0–4 bp) from cultured P. polylepis (isolate UIO036), and by 1.0–3.7% from other available Prymnesium sequences. The number of cells assumed to be P. polylepis began to increase in October 2007 coincidently with significantly calm and dry weather, and at their maximum the cells accounted for over 80% of the total phytoplankton biovolume in December–January. During...
Bente Edvardsen - One of the best experts on this subject based on the ideXlab platform.
-
characterisation of three novel giant viruses reveals huge diversity among viruses infecting Prymnesiales haptophyta
Virology, 2015Co-Authors: Torill Vik Johannessen, Gunnar Bratbak, Bente Edvardsen, Wenche Eikrem, Aud Larsen, Hiroyuki Ogata, Elianne Sirnaes Egge, Ruthanne SandaaAbstract:We have isolated three novel lytic dsDNA-viruses from Raunefjorden (Norway) that are putative members of the Mimiviridae family, namely Haptolina ericina virus RF02 (HeV RF02), Prymnesium kappa virus RF01 (PkV RF01), and Prymnesium kappa virus RF02 (PkV RF02). Each of the novel haptophyte viruses challenges the common conceptions of algal viruses with respect to host range, phylogenetic affiliation and size. PkV RF01 has a capsid of ~310 nm and is the largest algal virus particle ever reported while PkV RF01 and HeV RF02 were able to infect different species, even belonging to different genera. Moreover, PkV RF01 and HeV RF02 infected the same hosts, but phylogenetic analysis placed them in different groups. Our results reveal large variation among viruses infecting closely related microalgae, and challenge the common conception that algal viruses have narrow host range, and phylogeny reflecting their host affiliation.
-
the ecophysiology and bloom dynamics of prymnesium spp
Harmful Algae, 2012Co-Authors: Edna Granéli, Bente Edvardsen, Daniel L Roelke, Johannes A HagstromAbstract:Abstract Members of Prymnesium belong to the division Haptophyta, class Prymnesiophyceae, order Prymnesiales and family Prymnesiaceae. As most haptophytes, members of the genus Prymnesium are unicellular and planktonic. The most known of these species is the ichthyotoxic P. parvum, which may form nearly monospecific dense blooms in coastal and inland waters. This species possesses extraordinary plasticity concerning life survival strategies, and is specifically addressed in this review. Toxins produced by P. parvum have hemolytic properties, that not only kill fish but also co-existing plankton. These substances are allelopathic (when other algae are killed) and grazer deterrent (when grazers are killed). Allelopathy enables P. parvum to utilize inorganic nutrients present in the surrounding water without competition from other algal species; and by eliminating its grazers P. parvum reduces cell losses. The paralized microalgae and/or zooplankton, are therefter ingested by the P. parvum cells, a process called phagotrophy. P. parvum is also able of osmotrophy, i.e. utilization of dissolved organic matter. In this review, the cellular characteristics, life cycles, bloom formation, and factors affecting toxicity, allelopathy, phagotrophy, and osmotrophy of P. parvum are discussed.
-
Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta
2011Co-Authors: Bente Edvardsen, Ian Probert, Wenche Eikrem, Jahn Throndsen, Alberto G. Sáez, K. MedlinAbstract:Nucleotide sequences of the nuclear-encoded small subunit (18S rDNA) and partial large subunit (28S rDNA) ribosomal DNA were determined in 30 different species of the haptophyte genera Prymnesium, Chrysocampanula, Chrysochromulina, Imantonia and Platychrysis, all belonging to the order Prymnesiales. Phylogenies based on these and other available hapto-phyte 18S, 28S and plastid 16S rDNA sequences were reconstructed, and compared with available morphological and ultrastructural data. The rDNA phylogenies indicate that the genus Chrysochromulina is paraphyletic and is divided into two major clades. This is supported by ultrastructural and morphological data. There is a major split between Chrysochromulina species with a saddle-shaped cell form (clade B2) and the remaining species in the genus (clade B1). Clade B2 includes the type species C. parva and taxa belonging to this clade thus retain the name Chrysochromulina. The non-saddle-shaped Chrysochromulina species analysed are closely related to Hyalolithus, Prymnesium and Platychrysis species. Imantonia species are sister taxa to these species within clade B1. An amendment to the classification of the order Prymnesiales and the genera Prymnesium, Platychrysis and Chrysochromulina is proposed with one new and one emended family (Chrysochromulinaceae and Prymnesiaceae, respectively), two new genera (Haptolina and Pseudohaptolina), and one new species (Pseudohaptolina arctica). We suggest a revision of the taxonomy of the Prymnesiales that is in accordance with available molecular evidenc
-
Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta)
European Journal of Phycology, 2011Co-Authors: Bente Edvardsen, Alberto G. Sáez, Ian Probert, Wenche Eikrem, Jahn Throndsen, Linda MedlinAbstract:Nucleotide sequences of the nuclear-encoded small subunit (18S rDNA) and partial large subunit (28S rDNA) ribosomal DNA were determined in 30 different species of the haptophyte genera Prymnesium, Chrysocampanula, Chrysochromulina, Imantonia and Platychrysis, all belonging to the order Prymnesiales. Phylogenies based on these and other available haptophyte 18S, 28S and plastid 16S rDNA sequences were reconstructed, and compared with available morphological and ultrastructural data. The rDNA phylogenies indicate that the genus Chrysochromulina is paraphyletic and is divided into two major clades. This is supported by ultrastructural and morphological data. There is a major split between Chrysochromulina species with a saddle-shaped cell form (clade B2) and the remaining species in the genus (clade B1). Clade B2 includes the type species C. parva and taxa belonging to this clade thus retain the name Chrysochromulina. The non-saddle-shaped Chrysochromulina species analysed are closely related to Hyalolithus, Prymnesium and Platychrysis species. Imantonia species are sister taxa to these species within clade B1. An amendment to the classification of the order Prymnesiales and the genera Prymnesium, Platychrysis and Chrysochromulina is proposed with one new and one emended family (Chrysochromulinaceae and Prymnesiaceae, respectively), two new genera (Haptolina and Pseudohaptolina), and one new species (Pseudohaptolina arctica). We suggest a revision of the taxonomy of the Prymnesiales that is in accordance with available molecular evidence and supported by morphological data.
-
A review of the phylogeny of the Haptophyta
Coccolithophores, 2004Co-Authors: Alberto G. Sáez, Bente Edvardsen, Ian Probert, Jeremy R. Young, Wenche EikremAbstract:Most haptophytes are unicellular, photosynthetic flagellates, although some have coccoid, colonial, amoeboid or filamentous stages. Nearly all have a characteristic filamentous appendage, the haptonema, arising between the two flagella. We have amassed small subunit rRNA gene sequences (18S rDNA) from 125 haptophytes and aligned the sequences with those of over 300 published and unpublished chlorophyll a+c algae. Phylogenies were constructed using Bayesian, minimum evolution and weighted maximum parsimony analyses. The high divergence (6%) between members of Pavlova and the remaining haptophytes supports the division of the Haptophyta into two classes: the Prymnesiophyceae and the Pavlovophyceae (Edvardsen et al. 2000). Four major clades within the Prymnesiophyceae were identified that correspond to known taxa: one clade embraces Phaeocystales; the second includes members of the Prymnesiales; the third represents the Isochrysidales; and the fourth the Coccolithales. Two other minor clades contain taxa whose sequences were derived from a gene clone library. In the absence of information on cell morphology associated with these sequences we are unable to determine whether they belong to existing orders or if new orders should be erected. These taxa are not strongly related to any of the known cultured taxa. One to two per cent divergence in the 18S rRNA gene analysis warrants a separation above the level of family.
