masanobu kawachi | National Institute for Environmental Studies (original) (raw)

Papers by masanobu kawachi

Research paper thumbnail of PHYLOGENETIC POSITION OF SYMBIODINIUM (DINOPHYCEAE) ISOLATES FROM TRIDACNIDS (BIVALVIA), CARDIIDS (BIVALVIA), A SPONGE (PORIFERA), A SOFT CORAL (ANTHOZOA), AND A FREE-LIVING STRAIN

Journal of Phycology, 1999

The genus Symbiodinium is the commonly observed symbiotic dinoflagellate (zooxanthellae) that for... more The genus Symbiodinium is the commonly observed symbiotic dinoflagellate (zooxanthellae) that forms mutual associations with various marine invertebrates. Numerous studies have revealed that the genus is comprised of a group of diverse taxa, and information on the phylogenetic relationships among the genus’ members is increasing. In this study, small subunit (SSU) ribosomal RNA (ssrRNA) gene sequences were determined for 15 more Symbiodinium strains from 12 relatively unstudied host taxa (Indo-Pacific tridacnids, cardiids, sponge, and soft coral), 1 hitherto unreported free-living Symbiodinium strain, and 4 other Symbiodinium strains from four other host taxa (Indo-Pacific zoanthid, foraminifer, jellyfish, and mid-Pacific hard coral). Their respective phylogenetic positions were inferred, and strains that are either closely related to or distinct from previously reported Symbiodinium taxa were revealed. The cultured Symbiodinium strains isolated from individuals of six species of tridacnids and three species of cardiids all had identical ssrRNA gene sequences, are closely related to S. microadriaticum Freudenthal, and are indistinguishable from the RFLP Type A strain previously reported. However, the ssrRNA gene sequences of clam symbionts that were obtained via gene cloning were different from those of the cultured isolates and represent strains that are close to the RFLP Type C strains. The Symbiodinium-like dinoflagellate from the Indo-Pacific sponge Haliclona koremella De Laubenfels is distinct from any of the Symbiodinium taxa studied and may be similar to the symbiont previously isolated from the stony coral Montipora patula Quelch. The isolates from the soft coral Sarcophyton glaucum Quoy et Gaimard and from the zoanthid Zoanthus sp. are both very closely related to S. pilosum Trench et Blank. The free-living Symbiodinium isolate is very closely related to the symbiont isolated from the Indo-Pacific foraminifer Amphisorus hemprichii Ehrenberg, which in turn is distinct from the Red Sea strain isolated from a similar host. Theisolate from Cassiopeia sp. is different from S. microadriaticum F., the type species harbored by Cassiopeia xamachana Bigelow, and is instead very closely related to S. pulchrorum Trench isolated from a sea anemone. The symbiont from the stony coral M. verrucosa Lamarck is a sister taxon to the symbionts isolated from the foraminifera Marginopora kudakajimensis Gudmundsson and Sorites orbiculus Forskål. These data suggest that polymorphic symbioses extend from cnidarians to some bivalve, foraminifer, and jellyfish host species.

Research paper thumbnail of Taxonomy and the phylogenetic position of a new prasinophycean alga, Crustomastix didyma gen. & sp. nov. (Chlorophyta

Phycologia, 2000

ABSTRACT A new prasinophycean flagellate, Crustomastix didyma Nakayama, Kawachi & Inouye ... more ABSTRACT A new prasinophycean flagellate, Crustomastix didyma Nakayama, Kawachi & Inouye gen. & sp. nov., is described from the northwestern Pacific. This alga is elongate and bean-shaped and has two ventrally inserted, subequal flagella, with three types of hair scales. The entire cell and flagella are covered by a thin coat, which is probably derived from the Golgi apparatus and released through the duct system. The yellowish chloroplast is divided into two lobes connected by a narrow bridge. There is no pyrenoid or eyespot. The flagellar apparatus comprises the distal and proximal fibres, the Id and is microtubular roots, and a duct fibre. A multilayered structure (MLS) is associated with the Id root. Some features, such as the swimming behaviour, the transitional region, and the absence of microtubular roots associated with the number 2 basal body, suggest a close relationship to the Mamiellales. but this alga differs from other members of the Mamiellales in having a MLS and a duct system, which are found in the Pyramimonadales. Crusromastix didyma appears to be the most primitive member of the Mamiellales found so far and retains some characters of a putative common ancestor of the Mamiellales and Pyramimonadales. The discovery of this unique prasinophycean alga provides new insights into the phylogeny and evolution of the green algae.

Research paper thumbnail of Green-colored Plastids in the Dinoflagellate Genus Lepidodinium are of Core Chlorophyte Origin

Protist, 2011

Most photosynthetic dinoflagellates possess plastids containing chlorophyllsa+c,but species belon... more Most photosynthetic dinoflagellates possess plastids containing chlorophyllsa+c,but species belonging to the genus Lepidodiniumare unique in bearing non-canonical plastids containing chlorophyllsa+b. According to the pioneering works on pigment composition data, it has been proposed that Lepidodiniumplastids were derived from a prasinophyte species, though this hypothesis was not supported by a recent phylogenetic analysis based on an alignment comprised of eight plastid proteins (Takishita et al. 2008, Gene 410: 26-26). This "8-protein" analysis however was insufficient to clarify the origin of Lepidodiniumplastids for two major reasons: First, the alignment lacked sufficient evolutionary information to resolve the precise origin of Lepidodiniumplastids. Second, the taxa considered did not well represent the diversity of Chlorophyta. Particularly, prasinophytes were poorly sampled in the alignment. In this study, we sequenced plastid-encoded genes from L. chlorophorum, one pedinophyte species, one ulvophyte species, and six prasinophyte species. The 85 sequences newly determined in this study and recent progress in plastid genome sequencing enabled us to prepare an alignment comprised of 11 plastid proteins from green algal taxa that appropriately cover the diversity of Chlorophyta. All the analyses of the 11-protein data set robustly grouped L. chlorophorumwith members of the "core chlorophytes." Thus, we here propose that Lepidodiniumplastids are of core chlorophyte origin.

Research paper thumbnail of Mitochondrial Group II Introns in the Raphidophycean Flagellate Chattonella spp. Suggest a Diatom-to- Chattonella Lateral Group II Intron Transfer

Research paper thumbnail of Morphology, genetic diversity, temperature tolerance and toxicity of Cylindrospermopsis raciborskii (Nostocales, Cyanobacteria) strains from Thailand and Japan

Fems Microbiology Ecology, 2004

Research paper thumbnail of MOLECULAR PHYLOGENETIC ANALYSIS OF rbcL IN THE PRYMNESIOPHYTA1

Journal of Phycology, 1994

ABSTRACT The nucleotide sequences of rbcL genes encoding the large subunit of ribulose-1, 5-bisph... more ABSTRACT The nucleotide sequences of rbcL genes encoding the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) were determined from six species of Prymnesiophyta to clarify their phylogenetic relationships. Molecular phylogenetic trees were constructed using PAUP (Phylogenetic Analysis Using Parsimony). These analyses suggest that the Prymnesiophyta, except for the Pavlovales, area relatively stable monophyletic group. Pleurochrysis carterae, included in the Isochrysidales, is a sister ...

Research paper thumbnail of Sulcochrysis biplastida gen. et sp. nov.: Cell structure and absolute configuration of the flagellar apparatus of an enigmatic chromophyte alga

Phycological Research, 1995

Sulcochrysis biplastida gen. et sp. nov., a golden, marine, mixotrophic flagellate is described. ... more Sulcochrysis biplastida gen. et sp. nov., a golden, marine, mixotrophic flagellate is described. Cells resemble Ochromonas in light microscopic features, but they are distinct at the electron microscopic level from Ochromonas or any other typical chrysophyte.Ultrastructural features that discriminate Sulcochrysis from the Chrysophyceae are: (i) a proximal helix in the flagellar transition region; (ii) basal bodies situated in the anterior depression of the nucleus; (iii) the lack of the rhizoplast; and (iv) simple flagellar hairs lacking lateral filaments. These features suggest that Sulcochrysis is a relative of the Pedinellophyceae, Dictyochophyceae and Pelagophyceae. However, Sulcochrysis has a flagellar root system similar to that of the Ochromonas-type cell and it may use the R3 root for prey capture, as do ochromonadalean algae. The R3 root and the phagotrophic mechanism using the R3 root are interpreted as a plesiomorphy, because these are also distributed in primitive heterokonts such as the bicosoecids. Sulcochrysis has one microtubule probably homologous with the x-fibre of Bicosoeca maris Picken. Based on these features it is suggested that Sulcochrysis is an organism that links bicosoecids (Bicosoeco-phyceae), Pedinellophyceae, Dictyochophyceae and Pelagophyceae.

Research paper thumbnail of Denaturing gradient gel electrophoresis shows that bacterial communities change with mid-ocean ballast water exchange

Marine Pollution Bulletin, 2010

Research paper thumbnail of Effects of carbon source on growth and morphology of Botryococcus braunii

Journal of Applied Phycology, 2011

The green colonial alga Botryococcus braunii is characterized by the ability to produce and accum... more The green colonial alga Botryococcus braunii is characterized by the ability to produce and accumulate large amounts of hydrocarbons. We isolated and established an axenic clonal strain of B. braunii B70 and investigated the effects of organic carbon sources, including glucose, mannose, fructose, galactose, or acetate, on growth under light and dark conditions. This algal strain had the capacity to grow photo-, mixo-, or heterotrophically. Growth was promoted substantially following exposure of the algae to glucose or mannose under light exposure. Cells could grow under continuous darkness with glucose or mannose. In the presence of glucose under light or dark conditions, cell and colony size, and the intracellular granules containing oil, were markedly larger than those cultured without glucose.

Research paper thumbnail of Origins of plastids and glyceraldehyde-3-phosphate dehydrogenase genes in the green-colored dinoflagellate Lepidodinium chlorophorum

Research paper thumbnail of Ultrastructure and phylogenetic position of Chrysoculter rhomboideus gen. et sp. nov. (Prymnesiophyceae), a new flagellate haptophyte from Japanese coastal waters

Phycologia, 2005

... Takeshi Nakayama 1, *, Masaki Yoshida 1 , Mary-Hélène Noël 2 , Masanobu Kawachi 2 , and Isao ... more ... Takeshi Nakayama 1, *, Masaki Yoshida 1 , Mary-Hélène Noël 2 , Masanobu Kawachi 2 , and Isao Inouye 1 ... Whole mount preparations for transmission electron microscopy (TEM) were prepared using the method of Marin & Melkonian (1994). ...

Research paper thumbnail of MOLECULAR PHYLOGENY OF THE HAPTOPHYTA BASED ON THE rbcL GENE AND SEQUENCE VARIATION IN THE SPACER REGION OF THE RUBISCO OPERON

Journal of Phycology, 2001

A phylogeny of 21 haptophyte algae was inferred by maximum parsimony, neighbor-joining, and maxim... more A phylogeny of 21 haptophyte algae was inferred by maximum parsimony, neighbor-joining, and maximum likelihood analyses of sequences of the plastid-encoded gene, rbcL. Sequence variation in the spacer region of the RUBISCO operon was also investigated. In all the rbcL trees constructed, the haptophytes form two distinct clades: one includes the Pavlovales and the other includes the Prymnesiales, Coccosphaerales, and Isochrysidales (all sensuParke and Green 1976. This relationship coincides with the recent taxonomic treatment splitting the division into two subclasses, the Prymnesidae and Pavlovidae (Cavalier-Smith 1989) or the Prymnesiophycidae and the Pavlovophycidae using botanical suffixes ( Jordan and Green 1994), or into two classes, the Patelliferea and the Pavlovea (Cavalier-Smith 1993). In the Prymnesiophycidae, all the coccolithophorids examined are placed in a single clade, which suggests a single origin of the coccolithophorids and the ability of coccolith formation in the haptophytes. The genus Chrysochromulina is polyphyletic. Species of Chrysochromulina with a very long haptonema and a compressed cell body (typical of species including the type C. parva Lackey) form a clade, including Imantonia, that is often classified in the Isochrysidales in the neighbor-joining tree, whereas some species possessing a nontypical cell body and cell covering form a clade with Prymnesium and Platychrysis in all trees. It is suggested that loss of the haptonema in Imantonia and the reduction in Prymnesium and Platychrysis occurred secondarily and independently in two different lineages. Within the coccolithophorids, four clades are recognized: Pleurochrysis, Calyptrosphaera-Cruciplacolithus-Calcidiscus-Umbilicosphaera, Helicosphaera, and Emiliania-Gephyrocapsa. A non-coccolith-bearing haptophyte, Isochrysis, is an ingroup of the Emiliania-Gephyrocapsa clade, suggesting its secondary loss of the ability to form a coccolith. Sequence comparison of the spacer region of RUBISCO operon supports most results obtained in the analysis of rbcL sequences. Monophyly of the Prymnesiales sensu Parke and Green is still unclear because of low (<50%) bootstrap support for this group.

Research paper thumbnail of Phylogeny and ultrastructure of Nephroselmis and Pseudoscourfieldia (Chlorophyta), including the description of Nephroselmis anterostigmatica sp. nov. and a proposal for the Nephroselmidales ord. nov

Phycologia, 2007

ABSTRACT A new species of Nephroselmis, Nephroselmis anterostigmatica, is described from coastal ... more ABSTRACT A new species of Nephroselmis, Nephroselmis anterostigmatica, is described from coastal waters of the Palau Islands and the southern part of Japan. The long flagellum was stretched out at angle to the cell and showed a characteristic sigmoid line. A cup-shaped yellowish green chloroplast with two narrow sinuses included a pyrenoid with tubular invaginations of thylakoids. In contrast to other species of Nephroselmis, the eyespot was located at the anterior side of the cell. The transitional region of the flagellum possessed a single transitional plate and a stellate structure. The cell body was covered by two types of square scales (windmill/Maltese cross scales absent), small stellate scales and two types of large spiny scales. The flagellar surface was covered by inner square and outer rod-shaped scales, and ornamented with T- and PI-hairs. Tip hairs are absent. Nephroselmis anterostigmatica is superficially similar to Nephroselmis pyriformis (N. Carter) Ettl, but a detailed comparison of morphological characters, such as chloroplast shape, position of eyespot, composition of hair scales, presence or absence of the two types of small square scales and the large spiny scales, reveals clear differences between the two species. The molecular phylogenetic analysis on the basis of small subunit ribosomal DNA (SSU rDNA) sequences showed that N. anterostigmatica was not closely related to N. pyriformis, but was allied to Nephroselmis astigmatica Inouye &amp; Pienaar. Comparisons of the hair scales and SSU rDNA sequences confirm that the identity of strain CCMP717 is N. pyriformis, and Pseudoscoufieldia marina (Throndsen) Manton has flagella ornamented with a different type of hair scales. The morphological evolution within the genus Nephroselmis is discussed and the order Nephroselmidales is proposed.

Research paper thumbnail of A taxonomic re-evaluation of the Pedinellales (Dictyochophyceae), based on morphological, behavioural and molecular data

Phycologia, 2003

... using three characters: (I) whether the cell is sessile or free-swimming; (2) stalk ultrastru... more ... using three characters: (I) whether the cell is sessile or free-swimming; (2) stalk ultrastructure; and (3) the presence or absence of pyrenoids. ... The ambiguous definitions of Pedinella and Pseudopedi nella have led to confusion in the taxonomy of the Pedinel lales. ...

Research paper thumbnail of Taxonomic revision of Chattonella antiqua, C. marina and C. ovata (Raphidophyceae) based on their morphological characteristics and genetic diversity

Phycologia, 2009

ABSTRACT Three raphidophyte species, Chattonella antiqua, C. marina and C. ovata, are red tide-fo... more ABSTRACT Three raphidophyte species, Chattonella antiqua, C. marina and C. ovata, are red tide-forming harmful phytoplankton species, causing mass mortality at fish farms. These species were originally distinguished from each other solely based on their morphological characters. Recent genetic diversity analyses showed that the three species were extremely similar. It was therefore necessary to re-examine these three species to determine if they were independent single species. We compared 104 strains of the three species using morphological characters, nuclear ITS rDNA regions, the chloroplast rbcL gene, the mitochondrion COI gene and selected microsatellite regions. The morphological characters for the three species formed a continuum of variation instead of clearly defined limits. Compared with other selected heterokontophytes, their genetic divergence in the analyzed three regions was found to be at the intraspecies level, Microsatellite markers distinguished each of the 104 strains, but the strains apparently formed a single geographical population. Based on the morphological characters and the phylogenetic analyses, three groups, corresponding to each of the three Chattonella species, were roughly recognized. Nevertheless, this three-group distribution was insufficient to justify their distinction at the species rank. We therefore proposed a taxonomic revision with C antiqua and C ovata reduced to varieties of C marina, this latter having name priority. We proposed a new status: C marina var. antiqua (Hada) Demura &amp; Kawachi and C marina var. ovata (Y. Hara &amp; Chihara) Demura &amp; Kawachi.

Research paper thumbnail of Endangered algal species and how to protect them

Research paper thumbnail of Observations on the flagellar apparatus of a coccolithophorid, Cruciplacolithus neohelis (Prymnesiophyceae

Journal of Plant Research, 1994

The flagellar apparatus ofCruciplacolithus neohelis (McIntyre and Bé) Reinhardt including its tra... more The flagellar apparatus ofCruciplacolithus neohelis (McIntyre and Bé) Reinhardt including its transition region is described. The transition region contains a hat-shaped structure, which is suggested to be one of the common features of the Prymnesiophyceae. Its flagellar root system resembles that of most coccolithophorids examined so far, except that only one vestigial crystalline root is present associated with root 1. Two well-developed crystalline roots associated with roots 1 and 2, respectively, appear in the preprophase of nuclear division, suggesting conversion to a mitotic spindle. The taxonomic and evolutionary significance of the flagellar apparatus is discussed.

Research paper thumbnail of Re-examination of the marine 'chrysophyte' Polypodochrysis teissieri (Pinguiophyceae

Phycological Research, 2002

Research paper thumbnail of The Pinguiophyceae classis nova, a new class of photosynthetic stramenopiles whose members produce large amounts of omega-3 fatty acids

Phycological Research, 2002

The Pinguiophyceae class. nov., a new class of photo-synthetic stramenopiles (chromophytes), is d... more The Pinguiophyceae class. nov., a new class of photo-synthetic stramenopiles (chromophytes), is described. The class includes five monotypic genera, Glossomas-tix, Phaeomonas, Pinguiochrysis (type genus), Pinguio-coccus and Polypodochrysis. These ...

Research paper thumbnail of Phylogenetic Analysis of the SSU rRNA from Members of the Chrysophyceae

Research paper thumbnail of PHYLOGENETIC POSITION OF SYMBIODINIUM (DINOPHYCEAE) ISOLATES FROM TRIDACNIDS (BIVALVIA), CARDIIDS (BIVALVIA), A SPONGE (PORIFERA), A SOFT CORAL (ANTHOZOA), AND A FREE-LIVING STRAIN

Journal of Phycology, 1999

The genus Symbiodinium is the commonly observed symbiotic dinoflagellate (zooxanthellae) that for... more The genus Symbiodinium is the commonly observed symbiotic dinoflagellate (zooxanthellae) that forms mutual associations with various marine invertebrates. Numerous studies have revealed that the genus is comprised of a group of diverse taxa, and information on the phylogenetic relationships among the genus’ members is increasing. In this study, small subunit (SSU) ribosomal RNA (ssrRNA) gene sequences were determined for 15 more Symbiodinium strains from 12 relatively unstudied host taxa (Indo-Pacific tridacnids, cardiids, sponge, and soft coral), 1 hitherto unreported free-living Symbiodinium strain, and 4 other Symbiodinium strains from four other host taxa (Indo-Pacific zoanthid, foraminifer, jellyfish, and mid-Pacific hard coral). Their respective phylogenetic positions were inferred, and strains that are either closely related to or distinct from previously reported Symbiodinium taxa were revealed. The cultured Symbiodinium strains isolated from individuals of six species of tridacnids and three species of cardiids all had identical ssrRNA gene sequences, are closely related to S. microadriaticum Freudenthal, and are indistinguishable from the RFLP Type A strain previously reported. However, the ssrRNA gene sequences of clam symbionts that were obtained via gene cloning were different from those of the cultured isolates and represent strains that are close to the RFLP Type C strains. The Symbiodinium-like dinoflagellate from the Indo-Pacific sponge Haliclona koremella De Laubenfels is distinct from any of the Symbiodinium taxa studied and may be similar to the symbiont previously isolated from the stony coral Montipora patula Quelch. The isolates from the soft coral Sarcophyton glaucum Quoy et Gaimard and from the zoanthid Zoanthus sp. are both very closely related to S. pilosum Trench et Blank. The free-living Symbiodinium isolate is very closely related to the symbiont isolated from the Indo-Pacific foraminifer Amphisorus hemprichii Ehrenberg, which in turn is distinct from the Red Sea strain isolated from a similar host. Theisolate from Cassiopeia sp. is different from S. microadriaticum F., the type species harbored by Cassiopeia xamachana Bigelow, and is instead very closely related to S. pulchrorum Trench isolated from a sea anemone. The symbiont from the stony coral M. verrucosa Lamarck is a sister taxon to the symbionts isolated from the foraminifera Marginopora kudakajimensis Gudmundsson and Sorites orbiculus Forskål. These data suggest that polymorphic symbioses extend from cnidarians to some bivalve, foraminifer, and jellyfish host species.

Research paper thumbnail of Taxonomy and the phylogenetic position of a new prasinophycean alga, Crustomastix didyma gen. & sp. nov. (Chlorophyta

Phycologia, 2000

ABSTRACT A new prasinophycean flagellate, Crustomastix didyma Nakayama, Kawachi &amp; Inouye ... more ABSTRACT A new prasinophycean flagellate, Crustomastix didyma Nakayama, Kawachi &amp; Inouye gen. &amp; sp. nov., is described from the northwestern Pacific. This alga is elongate and bean-shaped and has two ventrally inserted, subequal flagella, with three types of hair scales. The entire cell and flagella are covered by a thin coat, which is probably derived from the Golgi apparatus and released through the duct system. The yellowish chloroplast is divided into two lobes connected by a narrow bridge. There is no pyrenoid or eyespot. The flagellar apparatus comprises the distal and proximal fibres, the Id and is microtubular roots, and a duct fibre. A multilayered structure (MLS) is associated with the Id root. Some features, such as the swimming behaviour, the transitional region, and the absence of microtubular roots associated with the number 2 basal body, suggest a close relationship to the Mamiellales. but this alga differs from other members of the Mamiellales in having a MLS and a duct system, which are found in the Pyramimonadales. Crusromastix didyma appears to be the most primitive member of the Mamiellales found so far and retains some characters of a putative common ancestor of the Mamiellales and Pyramimonadales. The discovery of this unique prasinophycean alga provides new insights into the phylogeny and evolution of the green algae.

Research paper thumbnail of Green-colored Plastids in the Dinoflagellate Genus Lepidodinium are of Core Chlorophyte Origin

Protist, 2011

Most photosynthetic dinoflagellates possess plastids containing chlorophyllsa+c,but species belon... more Most photosynthetic dinoflagellates possess plastids containing chlorophyllsa+c,but species belonging to the genus Lepidodiniumare unique in bearing non-canonical plastids containing chlorophyllsa+b. According to the pioneering works on pigment composition data, it has been proposed that Lepidodiniumplastids were derived from a prasinophyte species, though this hypothesis was not supported by a recent phylogenetic analysis based on an alignment comprised of eight plastid proteins (Takishita et al. 2008, Gene 410: 26-26). This &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;8-protein&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; analysis however was insufficient to clarify the origin of Lepidodiniumplastids for two major reasons: First, the alignment lacked sufficient evolutionary information to resolve the precise origin of Lepidodiniumplastids. Second, the taxa considered did not well represent the diversity of Chlorophyta. Particularly, prasinophytes were poorly sampled in the alignment. In this study, we sequenced plastid-encoded genes from L. chlorophorum, one pedinophyte species, one ulvophyte species, and six prasinophyte species. The 85 sequences newly determined in this study and recent progress in plastid genome sequencing enabled us to prepare an alignment comprised of 11 plastid proteins from green algal taxa that appropriately cover the diversity of Chlorophyta. All the analyses of the 11-protein data set robustly grouped L. chlorophorumwith members of the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;core chlorophytes.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; Thus, we here propose that Lepidodiniumplastids are of core chlorophyte origin.

Research paper thumbnail of Mitochondrial Group II Introns in the Raphidophycean Flagellate Chattonella spp. Suggest a Diatom-to- Chattonella Lateral Group II Intron Transfer

Research paper thumbnail of Morphology, genetic diversity, temperature tolerance and toxicity of Cylindrospermopsis raciborskii (Nostocales, Cyanobacteria) strains from Thailand and Japan

Fems Microbiology Ecology, 2004

Research paper thumbnail of MOLECULAR PHYLOGENETIC ANALYSIS OF rbcL IN THE PRYMNESIOPHYTA1

Journal of Phycology, 1994

ABSTRACT The nucleotide sequences of rbcL genes encoding the large subunit of ribulose-1, 5-bisph... more ABSTRACT The nucleotide sequences of rbcL genes encoding the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) were determined from six species of Prymnesiophyta to clarify their phylogenetic relationships. Molecular phylogenetic trees were constructed using PAUP (Phylogenetic Analysis Using Parsimony). These analyses suggest that the Prymnesiophyta, except for the Pavlovales, area relatively stable monophyletic group. Pleurochrysis carterae, included in the Isochrysidales, is a sister ...

Research paper thumbnail of Sulcochrysis biplastida gen. et sp. nov.: Cell structure and absolute configuration of the flagellar apparatus of an enigmatic chromophyte alga

Phycological Research, 1995

Sulcochrysis biplastida gen. et sp. nov., a golden, marine, mixotrophic flagellate is described. ... more Sulcochrysis biplastida gen. et sp. nov., a golden, marine, mixotrophic flagellate is described. Cells resemble Ochromonas in light microscopic features, but they are distinct at the electron microscopic level from Ochromonas or any other typical chrysophyte.Ultrastructural features that discriminate Sulcochrysis from the Chrysophyceae are: (i) a proximal helix in the flagellar transition region; (ii) basal bodies situated in the anterior depression of the nucleus; (iii) the lack of the rhizoplast; and (iv) simple flagellar hairs lacking lateral filaments. These features suggest that Sulcochrysis is a relative of the Pedinellophyceae, Dictyochophyceae and Pelagophyceae. However, Sulcochrysis has a flagellar root system similar to that of the Ochromonas-type cell and it may use the R3 root for prey capture, as do ochromonadalean algae. The R3 root and the phagotrophic mechanism using the R3 root are interpreted as a plesiomorphy, because these are also distributed in primitive heterokonts such as the bicosoecids. Sulcochrysis has one microtubule probably homologous with the x-fibre of Bicosoeca maris Picken. Based on these features it is suggested that Sulcochrysis is an organism that links bicosoecids (Bicosoeco-phyceae), Pedinellophyceae, Dictyochophyceae and Pelagophyceae.

Research paper thumbnail of Denaturing gradient gel electrophoresis shows that bacterial communities change with mid-ocean ballast water exchange

Marine Pollution Bulletin, 2010

Research paper thumbnail of Effects of carbon source on growth and morphology of Botryococcus braunii

Journal of Applied Phycology, 2011

The green colonial alga Botryococcus braunii is characterized by the ability to produce and accum... more The green colonial alga Botryococcus braunii is characterized by the ability to produce and accumulate large amounts of hydrocarbons. We isolated and established an axenic clonal strain of B. braunii B70 and investigated the effects of organic carbon sources, including glucose, mannose, fructose, galactose, or acetate, on growth under light and dark conditions. This algal strain had the capacity to grow photo-, mixo-, or heterotrophically. Growth was promoted substantially following exposure of the algae to glucose or mannose under light exposure. Cells could grow under continuous darkness with glucose or mannose. In the presence of glucose under light or dark conditions, cell and colony size, and the intracellular granules containing oil, were markedly larger than those cultured without glucose.

Research paper thumbnail of Origins of plastids and glyceraldehyde-3-phosphate dehydrogenase genes in the green-colored dinoflagellate Lepidodinium chlorophorum

Research paper thumbnail of Ultrastructure and phylogenetic position of Chrysoculter rhomboideus gen. et sp. nov. (Prymnesiophyceae), a new flagellate haptophyte from Japanese coastal waters

Phycologia, 2005

... Takeshi Nakayama 1, *, Masaki Yoshida 1 , Mary-Hélène Noël 2 , Masanobu Kawachi 2 , and Isao ... more ... Takeshi Nakayama 1, *, Masaki Yoshida 1 , Mary-Hélène Noël 2 , Masanobu Kawachi 2 , and Isao Inouye 1 ... Whole mount preparations for transmission electron microscopy (TEM) were prepared using the method of Marin &amp;amp;amp; Melkonian (1994). ...

Research paper thumbnail of MOLECULAR PHYLOGENY OF THE HAPTOPHYTA BASED ON THE rbcL GENE AND SEQUENCE VARIATION IN THE SPACER REGION OF THE RUBISCO OPERON

Journal of Phycology, 2001

A phylogeny of 21 haptophyte algae was inferred by maximum parsimony, neighbor-joining, and maxim... more A phylogeny of 21 haptophyte algae was inferred by maximum parsimony, neighbor-joining, and maximum likelihood analyses of sequences of the plastid-encoded gene, rbcL. Sequence variation in the spacer region of the RUBISCO operon was also investigated. In all the rbcL trees constructed, the haptophytes form two distinct clades: one includes the Pavlovales and the other includes the Prymnesiales, Coccosphaerales, and Isochrysidales (all sensuParke and Green 1976. This relationship coincides with the recent taxonomic treatment splitting the division into two subclasses, the Prymnesidae and Pavlovidae (Cavalier-Smith 1989) or the Prymnesiophycidae and the Pavlovophycidae using botanical suffixes ( Jordan and Green 1994), or into two classes, the Patelliferea and the Pavlovea (Cavalier-Smith 1993). In the Prymnesiophycidae, all the coccolithophorids examined are placed in a single clade, which suggests a single origin of the coccolithophorids and the ability of coccolith formation in the haptophytes. The genus Chrysochromulina is polyphyletic. Species of Chrysochromulina with a very long haptonema and a compressed cell body (typical of species including the type C. parva Lackey) form a clade, including Imantonia, that is often classified in the Isochrysidales in the neighbor-joining tree, whereas some species possessing a nontypical cell body and cell covering form a clade with Prymnesium and Platychrysis in all trees. It is suggested that loss of the haptonema in Imantonia and the reduction in Prymnesium and Platychrysis occurred secondarily and independently in two different lineages. Within the coccolithophorids, four clades are recognized: Pleurochrysis, Calyptrosphaera-Cruciplacolithus-Calcidiscus-Umbilicosphaera, Helicosphaera, and Emiliania-Gephyrocapsa. A non-coccolith-bearing haptophyte, Isochrysis, is an ingroup of the Emiliania-Gephyrocapsa clade, suggesting its secondary loss of the ability to form a coccolith. Sequence comparison of the spacer region of RUBISCO operon supports most results obtained in the analysis of rbcL sequences. Monophyly of the Prymnesiales sensu Parke and Green is still unclear because of low (<50%) bootstrap support for this group.

Research paper thumbnail of Phylogeny and ultrastructure of Nephroselmis and Pseudoscourfieldia (Chlorophyta), including the description of Nephroselmis anterostigmatica sp. nov. and a proposal for the Nephroselmidales ord. nov

Phycologia, 2007

ABSTRACT A new species of Nephroselmis, Nephroselmis anterostigmatica, is described from coastal ... more ABSTRACT A new species of Nephroselmis, Nephroselmis anterostigmatica, is described from coastal waters of the Palau Islands and the southern part of Japan. The long flagellum was stretched out at angle to the cell and showed a characteristic sigmoid line. A cup-shaped yellowish green chloroplast with two narrow sinuses included a pyrenoid with tubular invaginations of thylakoids. In contrast to other species of Nephroselmis, the eyespot was located at the anterior side of the cell. The transitional region of the flagellum possessed a single transitional plate and a stellate structure. The cell body was covered by two types of square scales (windmill/Maltese cross scales absent), small stellate scales and two types of large spiny scales. The flagellar surface was covered by inner square and outer rod-shaped scales, and ornamented with T- and PI-hairs. Tip hairs are absent. Nephroselmis anterostigmatica is superficially similar to Nephroselmis pyriformis (N. Carter) Ettl, but a detailed comparison of morphological characters, such as chloroplast shape, position of eyespot, composition of hair scales, presence or absence of the two types of small square scales and the large spiny scales, reveals clear differences between the two species. The molecular phylogenetic analysis on the basis of small subunit ribosomal DNA (SSU rDNA) sequences showed that N. anterostigmatica was not closely related to N. pyriformis, but was allied to Nephroselmis astigmatica Inouye &amp; Pienaar. Comparisons of the hair scales and SSU rDNA sequences confirm that the identity of strain CCMP717 is N. pyriformis, and Pseudoscoufieldia marina (Throndsen) Manton has flagella ornamented with a different type of hair scales. The morphological evolution within the genus Nephroselmis is discussed and the order Nephroselmidales is proposed.

Research paper thumbnail of A taxonomic re-evaluation of the Pedinellales (Dictyochophyceae), based on morphological, behavioural and molecular data

Phycologia, 2003

... using three characters: (I) whether the cell is sessile or free-swimming; (2) stalk ultrastru... more ... using three characters: (I) whether the cell is sessile or free-swimming; (2) stalk ultrastructure; and (3) the presence or absence of pyrenoids. ... The ambiguous definitions of Pedinella and Pseudopedi nella have led to confusion in the taxonomy of the Pedinel lales. ...

Research paper thumbnail of Taxonomic revision of Chattonella antiqua, C. marina and C. ovata (Raphidophyceae) based on their morphological characteristics and genetic diversity

Phycologia, 2009

ABSTRACT Three raphidophyte species, Chattonella antiqua, C. marina and C. ovata, are red tide-fo... more ABSTRACT Three raphidophyte species, Chattonella antiqua, C. marina and C. ovata, are red tide-forming harmful phytoplankton species, causing mass mortality at fish farms. These species were originally distinguished from each other solely based on their morphological characters. Recent genetic diversity analyses showed that the three species were extremely similar. It was therefore necessary to re-examine these three species to determine if they were independent single species. We compared 104 strains of the three species using morphological characters, nuclear ITS rDNA regions, the chloroplast rbcL gene, the mitochondrion COI gene and selected microsatellite regions. The morphological characters for the three species formed a continuum of variation instead of clearly defined limits. Compared with other selected heterokontophytes, their genetic divergence in the analyzed three regions was found to be at the intraspecies level, Microsatellite markers distinguished each of the 104 strains, but the strains apparently formed a single geographical population. Based on the morphological characters and the phylogenetic analyses, three groups, corresponding to each of the three Chattonella species, were roughly recognized. Nevertheless, this three-group distribution was insufficient to justify their distinction at the species rank. We therefore proposed a taxonomic revision with C antiqua and C ovata reduced to varieties of C marina, this latter having name priority. We proposed a new status: C marina var. antiqua (Hada) Demura &amp; Kawachi and C marina var. ovata (Y. Hara &amp; Chihara) Demura &amp; Kawachi.

Research paper thumbnail of Endangered algal species and how to protect them

Research paper thumbnail of Observations on the flagellar apparatus of a coccolithophorid, Cruciplacolithus neohelis (Prymnesiophyceae

Journal of Plant Research, 1994

The flagellar apparatus ofCruciplacolithus neohelis (McIntyre and Bé) Reinhardt including its tra... more The flagellar apparatus ofCruciplacolithus neohelis (McIntyre and Bé) Reinhardt including its transition region is described. The transition region contains a hat-shaped structure, which is suggested to be one of the common features of the Prymnesiophyceae. Its flagellar root system resembles that of most coccolithophorids examined so far, except that only one vestigial crystalline root is present associated with root 1. Two well-developed crystalline roots associated with roots 1 and 2, respectively, appear in the preprophase of nuclear division, suggesting conversion to a mitotic spindle. The taxonomic and evolutionary significance of the flagellar apparatus is discussed.

Research paper thumbnail of Re-examination of the marine 'chrysophyte' Polypodochrysis teissieri (Pinguiophyceae

Phycological Research, 2002

Research paper thumbnail of The Pinguiophyceae classis nova, a new class of photosynthetic stramenopiles whose members produce large amounts of omega-3 fatty acids

Phycological Research, 2002

The Pinguiophyceae class. nov., a new class of photo-synthetic stramenopiles (chromophytes), is d... more The Pinguiophyceae class. nov., a new class of photo-synthetic stramenopiles (chromophytes), is described. The class includes five monotypic genera, Glossomas-tix, Phaeomonas, Pinguiochrysis (type genus), Pinguio-coccus and Polypodochrysis. These ...

Research paper thumbnail of Phylogenetic Analysis of the SSU rRNA from Members of the Chrysophyceae