Dag Klaveness - Academia.edu (original) (raw)

Papers by Dag Klaveness

Research paper thumbnail of A physiological comparison of coccolith-forming and naked cells of Coccolithus huxleyi

Archives of Microbiology, 1970

In a naked clone of the coccolithophorid Coccolithus huxleyi, growth at light saturation was 15% ... more In a naked clone of the coccolithophorid Coccolithus huxleyi, growth at light saturation was 15% slower than in a coccolith-forming clone isolated from the same parent stock. The two cell types did not differ significantly with regard to cell volume and protein content. A 10–13% smaller chlorophyll a content of the naked cells was matched by a uniform lowering of

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Research paper thumbnail of Analysis of Environmental 18S Ribosomal RNA Sequences reveals Unknown Diversity of the Cosmopolitan Phylum Telonemia

Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary orig... more Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary origin. So far, only two Telonemia species, Telonema subtilis and Telonema antarcticum, have been described, but there are substantial variations in size and morphology among Telonema isolates and field observations, indicating a hidden diversity of Telonemia-like species and populations. In this study, we investigated the diversity and the global distribution of this group by analyzing 18S rDNA sequences from marine environmental clone libraries published in GenBank as well as several unpublished sequences from the Indian Ocean. Phylogenetic analyses of the identified sequences suggest that the Telonemia phylum includes several undescribed 18S rDNA phylotypes, probably corresponding to a number of different species and/or populations. The Telonemia phylotypes form two main groups, here referred to as Telonemia Groups 1 and 2. Some of the closely related sequences originate from separate oceans, indicating worldwide distributions of various Telonemia phylotypes, while other phylotypes seem to have limited geographical distribution. Further investigations of the evolutionary relationships within Telonemia should be conducted on isolated cultures of Telonema-like strains using multi-locus sequencing and morphological data.

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Research paper thumbnail of Telonemia, a new protist phylum with affinity to chromist lineages

Proceedings of The Royal Society B: Biological Sciences, 2006

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Research paper thumbnail of Coccolithus huxleyi (Lohm.) Kamptn II. The flagellate cell, aberrant cell types, vegetative propagation and life cycles

British Phycological Journal, 1972

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Research paper thumbnail of Phylogenetic Analyses Indicate that the 199Hexanoyloxy-fucoxanthin- Containing Dinoflagellates Have Tertiary Plastids of Haptophyte Origin

The three anomalously pigmented dinoflagellates Gymnodinium galatheanum, Gyrodinium aureolum,and ... more The three anomalously pigmented dinoflagellates Gymnodinium galatheanum, Gyrodinium aureolum,and Gymno- dinium breve have plastids possessing 199-hexanoyloxy-fucoxanthin as the major carotenoid rather than peridinin, which is characteristic of the majority of the dinoflagellates. Analyses of SSU rDNA from the plastid and the nuclear genome of these dinoflagellate species indicate that they have acquired their plastids via endosymbiosis of a haptophyte. The

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Research paper thumbnail of Meromictic Lakes as Habitats for Protists

The meromictic lake is, in effect, two different habitats separated by a distinct vertical gradie... more The meromictic lake is, in effect, two different habitats separated by a distinct vertical gradient (“the chemocline”, Hutchinson, 1937). By passing through the chemocline, the conditions with regard to dissolved salts and organic matter, particulates, gases and pH/eH may be altered significantly. Contrary to holomictic lakes where gradients may be established seasonally by temperature differences, the chemical gradient in truly

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Research paper thumbnail of Combined Heat Shock Protein 90 and Ribosomal RNA Sequence Phylogeny Supports Multiple Replacements of Dinoflagellate Plastids

The Journal of Eukaryotic Microbiology, 2006

Dinoflagellates harbour diverse plastids obtained from several algal groups, including haptophyte... more Dinoflagellates harbour diverse plastids obtained from several algal groups, including haptophytes, diatoms, cryptophytes, and prasinophytes. Their major plastid type with the accessory pigment peridinin is found in the vast majority of photosynthetic species. Some species of dinoflagellates have other aberrantly pigmented plastids. We sequenced the nuclear small subunit (SSU) ribosomal RNA (rRNA) gene of the "green" dinoflagellate Gymnodinium chlorophorum and show that it is sister to Lepidodinium viride, indicating that their common ancestor obtained the prasinophyte (or other green alga) plastid in one event. As the placement of dinoflagellate species that acquired green algal or haptophyte plastids is unclear from small and large subunit (LSU) rRNA trees, we tested the usefulness of the heat shock protein (Hsp) 90 gene for dinoflagellate phylogeny by sequencing it from four species with aberrant plastids (G. chlorophorum, Karlodinium micrum, Karenia brevis, and Karenia mikimotoi) plus Alexandrium tamarense, and constructing phylogenetic trees for Hsp90 and rRNAs, separately and together. Analyses of the Hsp90 and concatenated data suggest an ancestral origin of the peridinin-containing plastid, and two independent replacements of the peridinin plastid soon after the early radiation of the dinoflagellates. Thus, the Hsp90 gene seems to be a promising phylogenetic marker for dinoflagellate phylogeny.

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Research paper thumbnail of Freshwater Perkinsea and marine-freshwater colonizations revealed by pyrosequencing and phylogeny of environmental rDNA

The ISME Journal, 2010

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Research paper thumbnail of Analysis of Environmental 18S Ribosomal RNA Sequences reveals Unknown Diversity of the Cosmopolitan Phylum Telonemia

Protist, 2007

Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary orig... more Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary origin. So far, only two Telonemia species, Telonema subtilis and Telonema antarcticum, have been described, but there are substantial variations in size and morphology among Telonema isolates and field observations, indicating a hidden diversity of Telonemia-like species and populations. In this study, we investigated the diversity and the global distribution of this group by analyzing 18S rDNA sequences from marine environmental clone libraries published in GenBank as well as several unpublished sequences from the Indian Ocean. Phylogenetic analyses of the identified sequences suggest that the Telonemia phylum includes several undescribed 18S rDNA phylotypes, probably corresponding to a number of different species and/or populations. The Telonemia phylotypes form two main groups, here referred to as Telonemia Groups 1 and 2. Some of the closely related sequences originate from separate oceans, indicating worldwide distributions of various Telonemia phylotypes, while other phylotypes seem to have limited geographical distribution. Further investigations of the evolutionary relationships within Telonemia should be conducted on isolated cultures of Telonema-like strains using multi-locus sequencing and morphological data.

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Research paper thumbnail of Discovery of the toxic dinoflagellate Pfiesteria in northern European waters

Proceedings of the Royal Society B: Biological Sciences, 2002

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Research paper thumbnail of The utilization of organic nitrogen compounds as sole nitrogen source by some freshwater phytoplankters

Nordic Journal of Botany, 1986

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Research paper thumbnail of Heterotachy Processes in Rhodophyte-Derived Secondhand Plastid Genes: Implications for Addressing the Origin and Evolution of Dinoflagellate Plastids

Molecular Biology and Evolution, 2006

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Research paper thumbnail of Phenotypically Different Microalgal Morphospecies with Identical Ribosomal DNA: A Case of Rapid Adaptive Evolution?

Microbial Ecology, 2007

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Research paper thumbnail of Structure of Extracellular Polysaccharides Produced by a Soil Cryptomonas Sp. (CRYPTOPHYCEAE)1

Journal of Phycology, 1992

Page 1. J. Phyrot. 28,61-63(1992) NOTE STRUCTURE OF EXTRACELLULAR POLYSACCHARIDES PRODUCED BY A S... more Page 1. J. Phyrot. 28,61-63(1992) NOTE STRUCTURE OF EXTRACELLULAR POLYSACCHARIDES PRODUCED BY A SOIL CRYPTOMONAS SP. (CRYPTOPHYCEAE)1 Berit Smestad Paulsen ¡nsiiuite of Pharmacy, Department of Pharmacognosy. ...

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Research paper thumbnail of Studies on Polysaccharides From Three Edible Species of Nostoc (Cyanobacteria) With Different Colony Morphologies: Comparison of Monosaccharide Compositions and Viscosities of Polysaccharides From Field Colonies and Suspension Cultures

Journal of Phycology, 1998

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Research paper thumbnail of Telonema antarcticum sp. nov., a common marine phagotrophic flagellate

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2005

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Research paper thumbnail of Large-Scale Phylogenomic Analyses Reveal That Two Enigmatic Protist Lineages, Telonemia and Centroheliozoa, Are Related to Photosynthetic Chromalveolates

Genome Biology and Evolution, 2010

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Research paper thumbnail of Diversification of unicellular eukaryotes: cryptomonad colonizations of marine and fresh waters inferred from revised 18S rRNA phylogeny

Environmental Microbiology, 2008

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Research paper thumbnail of Extracellular carbohydrate polymers from five desert soil algae with different cohesion in the stabilization of fine sand grain

Carbohydrate Polymers, 2003

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Research paper thumbnail of A phylogenetic mosaic plastid proteome and unusual plastid-targeting signals in the green-colored dinoflagellate Lepidodinium chlorophorum

BMC Evolutionary Biology, 2010

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Research paper thumbnail of A physiological comparison of coccolith-forming and naked cells of Coccolithus huxleyi

Archives of Microbiology, 1970

In a naked clone of the coccolithophorid Coccolithus huxleyi, growth at light saturation was 15% ... more In a naked clone of the coccolithophorid Coccolithus huxleyi, growth at light saturation was 15% slower than in a coccolith-forming clone isolated from the same parent stock. The two cell types did not differ significantly with regard to cell volume and protein content. A 10–13% smaller chlorophyll a content of the naked cells was matched by a uniform lowering of

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Research paper thumbnail of Analysis of Environmental 18S Ribosomal RNA Sequences reveals Unknown Diversity of the Cosmopolitan Phylum Telonemia

Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary orig... more Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary origin. So far, only two Telonemia species, Telonema subtilis and Telonema antarcticum, have been described, but there are substantial variations in size and morphology among Telonema isolates and field observations, indicating a hidden diversity of Telonemia-like species and populations. In this study, we investigated the diversity and the global distribution of this group by analyzing 18S rDNA sequences from marine environmental clone libraries published in GenBank as well as several unpublished sequences from the Indian Ocean. Phylogenetic analyses of the identified sequences suggest that the Telonemia phylum includes several undescribed 18S rDNA phylotypes, probably corresponding to a number of different species and/or populations. The Telonemia phylotypes form two main groups, here referred to as Telonemia Groups 1 and 2. Some of the closely related sequences originate from separate oceans, indicating worldwide distributions of various Telonemia phylotypes, while other phylotypes seem to have limited geographical distribution. Further investigations of the evolutionary relationships within Telonemia should be conducted on isolated cultures of Telonema-like strains using multi-locus sequencing and morphological data.

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Research paper thumbnail of Telonemia, a new protist phylum with affinity to chromist lineages

Proceedings of The Royal Society B: Biological Sciences, 2006

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Research paper thumbnail of Coccolithus huxleyi (Lohm.) Kamptn II. The flagellate cell, aberrant cell types, vegetative propagation and life cycles

British Phycological Journal, 1972

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Research paper thumbnail of Phylogenetic Analyses Indicate that the 199Hexanoyloxy-fucoxanthin- Containing Dinoflagellates Have Tertiary Plastids of Haptophyte Origin

The three anomalously pigmented dinoflagellates Gymnodinium galatheanum, Gyrodinium aureolum,and ... more The three anomalously pigmented dinoflagellates Gymnodinium galatheanum, Gyrodinium aureolum,and Gymno- dinium breve have plastids possessing 199-hexanoyloxy-fucoxanthin as the major carotenoid rather than peridinin, which is characteristic of the majority of the dinoflagellates. Analyses of SSU rDNA from the plastid and the nuclear genome of these dinoflagellate species indicate that they have acquired their plastids via endosymbiosis of a haptophyte. The

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Meromictic Lakes as Habitats for Protists

The meromictic lake is, in effect, two different habitats separated by a distinct vertical gradie... more The meromictic lake is, in effect, two different habitats separated by a distinct vertical gradient (“the chemocline”, Hutchinson, 1937). By passing through the chemocline, the conditions with regard to dissolved salts and organic matter, particulates, gases and pH/eH may be altered significantly. Contrary to holomictic lakes where gradients may be established seasonally by temperature differences, the chemical gradient in truly

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Research paper thumbnail of Combined Heat Shock Protein 90 and Ribosomal RNA Sequence Phylogeny Supports Multiple Replacements of Dinoflagellate Plastids

The Journal of Eukaryotic Microbiology, 2006

Dinoflagellates harbour diverse plastids obtained from several algal groups, including haptophyte... more Dinoflagellates harbour diverse plastids obtained from several algal groups, including haptophytes, diatoms, cryptophytes, and prasinophytes. Their major plastid type with the accessory pigment peridinin is found in the vast majority of photosynthetic species. Some species of dinoflagellates have other aberrantly pigmented plastids. We sequenced the nuclear small subunit (SSU) ribosomal RNA (rRNA) gene of the "green" dinoflagellate Gymnodinium chlorophorum and show that it is sister to Lepidodinium viride, indicating that their common ancestor obtained the prasinophyte (or other green alga) plastid in one event. As the placement of dinoflagellate species that acquired green algal or haptophyte plastids is unclear from small and large subunit (LSU) rRNA trees, we tested the usefulness of the heat shock protein (Hsp) 90 gene for dinoflagellate phylogeny by sequencing it from four species with aberrant plastids (G. chlorophorum, Karlodinium micrum, Karenia brevis, and Karenia mikimotoi) plus Alexandrium tamarense, and constructing phylogenetic trees for Hsp90 and rRNAs, separately and together. Analyses of the Hsp90 and concatenated data suggest an ancestral origin of the peridinin-containing plastid, and two independent replacements of the peridinin plastid soon after the early radiation of the dinoflagellates. Thus, the Hsp90 gene seems to be a promising phylogenetic marker for dinoflagellate phylogeny.

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Research paper thumbnail of Freshwater Perkinsea and marine-freshwater colonizations revealed by pyrosequencing and phylogeny of environmental rDNA

The ISME Journal, 2010

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Research paper thumbnail of Analysis of Environmental 18S Ribosomal RNA Sequences reveals Unknown Diversity of the Cosmopolitan Phylum Telonemia

Protist, 2007

Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary orig... more Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary origin. So far, only two Telonemia species, Telonema subtilis and Telonema antarcticum, have been described, but there are substantial variations in size and morphology among Telonema isolates and field observations, indicating a hidden diversity of Telonemia-like species and populations. In this study, we investigated the diversity and the global distribution of this group by analyzing 18S rDNA sequences from marine environmental clone libraries published in GenBank as well as several unpublished sequences from the Indian Ocean. Phylogenetic analyses of the identified sequences suggest that the Telonemia phylum includes several undescribed 18S rDNA phylotypes, probably corresponding to a number of different species and/or populations. The Telonemia phylotypes form two main groups, here referred to as Telonemia Groups 1 and 2. Some of the closely related sequences originate from separate oceans, indicating worldwide distributions of various Telonemia phylotypes, while other phylotypes seem to have limited geographical distribution. Further investigations of the evolutionary relationships within Telonemia should be conducted on isolated cultures of Telonema-like strains using multi-locus sequencing and morphological data.

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Research paper thumbnail of Discovery of the toxic dinoflagellate Pfiesteria in northern European waters

Proceedings of the Royal Society B: Biological Sciences, 2002

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Research paper thumbnail of The utilization of organic nitrogen compounds as sole nitrogen source by some freshwater phytoplankters

Nordic Journal of Botany, 1986

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Research paper thumbnail of Heterotachy Processes in Rhodophyte-Derived Secondhand Plastid Genes: Implications for Addressing the Origin and Evolution of Dinoflagellate Plastids

Molecular Biology and Evolution, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Phenotypically Different Microalgal Morphospecies with Identical Ribosomal DNA: A Case of Rapid Adaptive Evolution?

Microbial Ecology, 2007

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Research paper thumbnail of Structure of Extracellular Polysaccharides Produced by a Soil Cryptomonas Sp. (CRYPTOPHYCEAE)1

Journal of Phycology, 1992

Page 1. J. Phyrot. 28,61-63(1992) NOTE STRUCTURE OF EXTRACELLULAR POLYSACCHARIDES PRODUCED BY A S... more Page 1. J. Phyrot. 28,61-63(1992) NOTE STRUCTURE OF EXTRACELLULAR POLYSACCHARIDES PRODUCED BY A SOIL CRYPTOMONAS SP. (CRYPTOPHYCEAE)1 Berit Smestad Paulsen ¡nsiiuite of Pharmacy, Department of Pharmacognosy. ...

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Research paper thumbnail of Studies on Polysaccharides From Three Edible Species of Nostoc (Cyanobacteria) With Different Colony Morphologies: Comparison of Monosaccharide Compositions and Viscosities of Polysaccharides From Field Colonies and Suspension Cultures

Journal of Phycology, 1998

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Research paper thumbnail of Telonema antarcticum sp. nov., a common marine phagotrophic flagellate

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Large-Scale Phylogenomic Analyses Reveal That Two Enigmatic Protist Lineages, Telonemia and Centroheliozoa, Are Related to Photosynthetic Chromalveolates

Genome Biology and Evolution, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Diversification of unicellular eukaryotes: cryptomonad colonizations of marine and fresh waters inferred from revised 18S rRNA phylogeny

Environmental Microbiology, 2008

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Research paper thumbnail of Extracellular carbohydrate polymers from five desert soil algae with different cohesion in the stabilization of fine sand grain

Carbohydrate Polymers, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A phylogenetic mosaic plastid proteome and unusual plastid-targeting signals in the green-colored dinoflagellate Lepidodinium chlorophorum

BMC Evolutionary Biology, 2010

Bookmarks Related papers MentionsView impact