Sterols of the green-pigmented, aberrant plastid dinoflagellate, Lepidodinium chlorophorum (Dinophyceae)

Lepidodinium chlorophorum is a green-pigmented dinoflagellate with an aberrant, tertiary plastid of chlorophyte ancestry rather than the typical red algal, secondary endosymbiont found in the vast majority of photosynthetic dinoflagellates. To date, only one published study exists on the galactolipids of L. chlorophorum, with nothing known about other lipid classes, including sterols. Our objectives were to examine the sterol composition of L. chlorophorum to determine if it produces any unique sterols with the potential to serve as biomarkers, and to compare it to members of the Chlorophyceae to determine if it has inherited any signature green algal sterols from its chlorophyte-derived endosymbiont. We have found that L. chlorophorum produces 6 sterols, all with a 4α-methyl substituent and none of which are known to occur in the Chlorophyceae. Rather, the sterols produced by L. chlorophorum place it within a group of dinoflagellates that have the common dinoflagellate sterols, dinosterol and dinostanol, as part of their sterol composition.     

Durinskia baltica (Dinophyceae), a newly recorded species and genus from China, and its systematics

A freshwater dinoflagellate was identified as Durinskia baltica (Levander) Carty & Cox by morphological characteristics,with the plate formula:Po,x,4',2a,6',5c,4s,5',2'.Durinskia was a newly recorded dinoflagellate genus for China with two anterior intercalary plates and six characteristic precingular plates.Partial sequences of the small and large subunit ribosomal DNA and internal transcribed spacer sequences for the dinoflagellate cells were obtained from field samples.Molecular phylogenetic results indicated Durinskia species could cluster into a monophyletic group,which were distinct from Peridinium species.According to morphological and molecular evidence,it was agreed that the genus Durinskia was separated from the genus Peridinium,which could be a polyphyletic group.In addition,D.baltica was an infrequent diatom-harboring dinoflagellate which was known to possess an endosymbiotic diatom or diatom-like alga.The phylogenetic analyses indicated that D.baltica had a close affinity with Peridiniopsis penardii and P.niei,common freshwater bloom-forming species in China.     

Sterols of the syndinian dinoflagellate Amoebophrya sp., a parasite of the dinoflagellate Alexandrium tamarense (Dinophyceae)

Several harmful photosynthetic dinoflagellates have been examined over past decades for unique chemical biomarker sterols. Little emphasis has been placed on important heterotrophic genera, such as Amoebophrya, an obligate, intracellular parasite of other, often harmful, dinoflagellates with the ability to control host populations naturally. Therefore, the sterol composition of Amoebophrya was examined throughout the course of an infective cycle within its host dinoflagellate, Alexandrium tamarense, with the primary intent of identifying potential sterol biomarkers. Amoebophrya possessed two primary C(27) sterols, cholesterol and cholesta-5,22Z-dien-3beta-ol (cis-22-dehydrocholesterol), which are not unique to this genus, but were found in high relative percentages that are uncommon to other genera of dinoflagellates. Because the host also possesses cholesterol as one of its major sterols, carbon-stable isotope ratio characterization of cholesterol was performed in order to determine whether it was produced by Amoebophrya or derived intact from the host. Results indicated that cholesterol was not derived intact from the host. A comparison of the sterol profile of Amoebophrya to published sterol profiles of phylogenetic relatives revealed that its sterol profile most closely resembles that of the (proto)dinoflagellate Oxyrrhis marina rather than other extant genera.     

Sterols of the heterotrophic dinoflagellate,pfiesteria piscicida (dinophyceae): is there a lipid biomarker?1

Within U.S. waters, blooms of the dinoflagellate, Pfiesteria piscicida, have been recorded on an almost regular basis in the Chesapeake Bay and surrounding mid‐Atlantic regions for the last two decades. Despite the apparent significance of such blooms to the environment and human health and the attendant economic consequences, little work has addressed the physiology and biochemistry, particularly that of sterol composition, of P. piscicida. GC‐MS characterization of trimethylsilyl ether derivatives of sterols from free sterol and sterol ester fractions was performed in an effort to determine whether P. piscicida produces unique sterols that may serve as potential biomarkers. This characterization revealed that like most dinoflagellates, the majority of sterols was present as free sterols. Furthermore, the profile of free sterols was found to resemble those of photosynthetic dinoflagellates, with the dominant compound being the previously reported dinoflagellate sterol, dinosterol. A number of other 4α‐methyl‐substituted sterols and steroidal ketones common to other dinoflagellates were also identified. No strong candidate(s) for a unique sterol biomarker was present.     

Description of a new dinoflagellate with a diatom endosymbiont, <Emphasis Type="Italic">Durinskia capensis</Emphasis> sp. nov. (Peridiniales,Dinophyceae) from South Africa

A new dinoflagellate Durinskia capensis Pienaar, Sakai et Horiguchi sp. nov. (Peridiniales, Dinophyceae), from tidal pools along the west coast of the Cape Peninsula, Republic of South Africa, is described. The dinoflagellate produces characteristic dense orange-red colored blooms in tidal pools. The organism is characterized by having a eukaryotic endosymbiotic alga. Ultrastructure study revealed the organism has a cellular construction similar to that of other diatom-harboring dinoflagellates. The cell is thecate and the plate formula is: Po, x, 4', 2a, 6', 5c, 4s, 5', 2', which is the same as that of Durinskia baltica, the type species of the genus Durinskia. D. capensis can, however, be distinguished from D. baltica by overall cell shape, the relative size of the 1a and 2a plates, the degree of cingular displacement, and the shape of the eyespot. Our molecular analysis based on SSU rDNA revealed that D. capensis is closely allied to D. baltica, thus supporting the assignment of this new species to this genus. This Durinskia clade takes a sister position to another diatom-harboring dinoflagellate clade, which includes Kryptoperidinium foliaceum and Galeidinium rugatum. Molecular analysis based on the rbcL gene sequence and ultrastructure study revealed that the endosymbiont of D. capensis is a diatom. The SSU rDNA gene trees indicated that four species with a diatom endosymbiont formed a clade, suggesting a single endosymbiotic origin.     

First examination of sterols in the marine dinoflagellate genus Vulcanodinium

Vulcanodinium is an ecologically relevant dinoflagellate genus due to its production of neurotoxins known as pinnatoxins. We present here the first examination of the sterols of a Vulcanodinium rugosum isolate. Sterols are ringed lipids that assist in maintaining rigidity of cellular membranes, and the Dinophyceae are well-studied for their ability to produce a diverse array of sterols, many of which have chemotaxonomic utility. We have determined that V. rugosum produces a set of major sterols, namely cholesterol, dinosterol, 4α,24-dimethyl-5α-cholest-22E-en-3β-ol, and 4α,24-dimethyl-5α-cholestan-3β-ol, common to the Dinophyceae. However, this displayed marked differences from those studied members of the genera Scrippsiella and Peridinium, the closest phylogenetic relatives. Included in these differences is production by V. rugosum of a much lower percentage of dinostanol, a saturated form of dinosterol.     

Sterols of morphologically distinct,okadaic acid-producing Prorocentrum texanum var. texanum and var. cuspidatum isolated from the Gulf of Mexico

Prorocentrum texanum var. texanum and its morphologically distinct yet genetically identical (as based on the sequences of five genes) variety P. texanum var. cuspidatum represent a species of Prorocentrum recently isolated from the Gulf of Mexico. Together, these two varieties represent a sister species to Prorocentrum micans. P. micans has had its sterols, which are ringed lipids common to eukaryotic cell membranes, shown in some studies to be comprised of cholesterol (cholest-5-en-3β-ol), 23,24-dimethyl-cholesta-5,22-dien-3β-ol, 23,24-dimethyl-5α-cholest-22E-en-3β-ol, dinosterol, and 4α,23,24-trimethyl-5α-cholestan-3β-ol (dinostanol) as major sterols, thus placing it within a previously identified cluster of dinoflagellates characterized by the predominance of cholesterol and dinosterol. In this study we have determined the sterol compositions of these two varieties of P. texanum to be abundant in cholesterol, 23,24-dimethyl-cholesta-5,22-dien-3β-ol, 23,24-dimethyl-5α-cholest-22E-en-3β-ol, dinosterol, and dinostanol such that the varieties are virtually indistinguishable from each other, making them both in general agreement with the sterols of P. micans, its closest species relative. This expands our knowledge of the sterols of this environmentally important dinoflagellate genus.     

Sterols of the Toxic Marine Dinoflagellate,Pyrodinium bahamense

Pyrodinium bahamense is a dinoflagellate of concern in subtropical and tropical coastal environments. To date, there is only a single published study on its fatty acids, but no published data on its sterol composition. Sterols, which are membrane‐reinforcing lipids in eukaryotes, display a great diversity of structures in dinoflagellates, with some serving as chemotaxonomic markers. We have examined the sterol compositions of two isolates of P. bahamense from Indian River Lagoon and Tampa Bay, Florida, and have found both to produce three sterols: cholesterol, dinosterol, and 4α‐methylgorgostanol. All three sterols are found in closely related, armored taxa.     

Morphological and molecular characterization of the small armoured dinoflagellate Heterocapsa minima (Peridiniales,Dinophyceae)

The dinophycean genus Heterocapsa is of considerable interest as it contains a number of bloom-forming and/or harmful species. Fine structure of organic body scales is regarded as the most important morphological feature for species determination but currently is unknown for the species H. minima described by Pomroy 25 years ago. Availability of a culture of H. minima collected in the south-west of Ireland allowed us to provide important information for this species, including cell size, cell organelle location, thecal plate pattern, body scale fine structure and molecular phylogeny. Light microscopy revealed the presence of one reticulate chloroplast, an elongated centrally located nucleus, and the presence of one pyrenoid surrounded by a starch sheath. Scanning electron microscopy (SEM) of the thecal plate pattern indicated that Pomroy erroneously designated the narrow first cingular plate as a sulcal plate. In addition, SEM revealed as yet unreported details of the apical pore complex and uncommon ornamentations of hypothecal plates. Organic body scales of H. minima were about 400 nm in size, roundish, with a small central hole and one central, six peripheral and three radiating spines. They differ from other body scales described within this genus allowing for positive identification of H. minima. Heterocapsa minima shares gross cell morphological features (hyposome smaller than episome, elongated nucleus in the middle of the cell, one pyrenoid located in the episome on its left side) with H. arctica (both subspecies H. arctica subsp. arctica and H. arctica subsp. frigida), H. lanceolata and H. rotundata. These relationships are reflected in the phylogenetic trees based on LSU and ITS rDNA sequence data, which identified H. arctica (both subspecies), H. rotundata and H. lanceolata as close relatives of H. minima.     

Mono- and digalactosyldiacylglycerol composition of dinoflagellates. V. The galactolipid profile of Alexandrium tamarense (Dinophyceae) during the course of infection by the parasitic syndinian dinoflagellate Amoebophrya sp.

Amoebophrya is a parasitic, syndinian dinoflagellate genus that must infect another host dinoflagellate in order to reproduce. Work by Park et al. [Mar. Ecol. Prog. Ser., 227: 281–292 (2002)] has led to the hypothesis that Amoebophrya's development within a host cell nucleus disrupts the flow of genetic information involved in plastidial function. The possibility that genetic disruption by this parasite could lead to alterations in plastidial lipid composition during the course of an infection has not yet been elucidated. Our primary objective in this lipidomic study was to examine the chloroplast membrane galactolipid composition of Alexandrium tamarense infected by an Amoebophrya species in order to determine whether infection of A. tamarense causes a phenotypic alteration in the composition of mono- and digalactosyldiacylglycerol (MGDG and DGDG, respectively), two galactolipids that comprise the majority of photosynthetic membranes. Our secondary objective was to determine if non-photosynthetic Amoebophrya sp. either incorporated host cell MGDG and DGDG, and/or itself produced forms of MGDG and DGDG, as has been observed previously in heterotrophic apicomplexan parasites distantly related to Amoebophrya. We found that, despite development of Amoebophrya sp. within the nucleus, the composition of A. tamarense MGDG and DGDG did not change throughout the infection process. The predominant forms of these galactolipids were 18:5/18:4 (sn???1/sn?2) and 20:5/18:4 DGDG, which were present at similar abundances in both an uninfected host and a host late in the infection process just prior to release of Amoebophrya sp. dinospores. Amoebophrya sp. did not possess appreciable amounts of any forms of MGDG and DGDG.     

Growth of the toxic dinoflagellate Alexandrium minutum (Dinophyceae) using high biomass culture systems

Toxic dinoflagellates are important in natural ecosystems and are ofglobal economic significance because of the impact of toxic blooms onaquaculture and human health. Both the organisms and the toxins they producehave potential for biotechnology applications. We investigated autotrophicgrowth of a toxic dinoflagellate, Alexandrium minutum, inthree different high biomass culture systems, assessing growth, productivityandtoxin production. The systems used were: aerated and non-aerated2-L Erlenmeyer flasks; 0.5-L glass aerated tubes; anda 4-L laboratory scale alveolar panel photobioreactor. A range ofindicators was used to assess growth in these systems. Alexandriumminutum grew well in all culture conditions investigated, with amarked increase in both biomass and productivity in response to aeration. Thehighest cell concentration (4.9 × 10⁵ cellsmL^–1) and productivity (2.6 ×10⁴cells mL^–1d^–1) was achieved inthe aerated glass culture tubes. Stable growth of A.minutum in the laboratory scale alveolar panel photobioreactor wasmaintained over a period of five months, with a maximum cell concentration of3.3 × 10⁵ cells mL^–1, a meanproductivity of 1.4 × 10⁴ cells mL^–1d^–1, and toxin production of approximately 20g L^–1 d^–1 with weeklyharvesting.     

New records of Scaphodinium mirabile (Dinophyceae), an unnoticed dinoflagellate in the Pacific Ocean

Previous records of dinoflagellate Scaphodinium mirabile Margalef (Leptodiscaceae, Noctilucales) were restricted to the Mediterranean‐Black Sea and Eastern Atlantic Ocean. Nine and 34 specimens were observed in the upper 100 m layer in May and July, respectively, in a cross‐section in the vicinity of the Kuroshio Current (NW Pacific Ocean). Nearly all the Lugol‐fixed specimens appeared folded over themselves, an appearance that differs from the view reported in the scarce literature available.     

PCR detection of dinoflagellate cysts in field sediment samples from tropic and temperate environments

Species-specific primers were constructed for Scrippsiella trochoidea, Protoceratium reticulatum and Lingulodinium polyedrum, which all are common cosmopolitan cyst forming dinoflagellates. The designed primers amplified a product of expected size from cultured planktonic cells of the three species, and did not yield any product with a wide range of other algal species used as negative controls. The PCR method for detection and identification of dinoflagellate cysts from the three species was applied on field samples. Undisturbed surface sediment was collected along the southwest coast of India and the west coast of Sweden. DNA extract from sediment including DNA from dinoflagellate cysts could be obtained after repeated grinding with mortar and pestle under liquid nitrogen followed by microwave boiling. All sediment samples that contained any of the target species as confirmed by microscopy, were also positive for PCR. Field samples negative for any of the target species by microscopy, were also negative by PCR. Restriction enzyme digestion and/or DNA sequencing confirmed the specificity of all the PCR products from field samples. The yield of DNA from sediment extraction was low, and therefore nested PCR was necessary for accurate species-specific detection of the three species in most of the field samples.     

High production of unexpected carotenoids in Dinophyceae. Astaxanthin esters from the freshwater dinoflagellate Tovellia sanguinea

A wide range of photopigments biosynthesised by a unialgal cell culture of the red dinoflagellate Tovellia sanguinea, the blooms of which were responsible for the summer reddening of the waters of the Lake Tovel until 1964, have been identified through reversed-phase high pressure liquid chromatography (HPLC) coupled to photodiode array detector (PDAD) and to atmospheric pressure ionisation mass spectrometer (API-MS). Myristoyl and palmitoyl astaxanthin esters were the most abundant pigments of T. sanguinea, whereas other carotenoids, considered to be diagnostic markers for dinoflagellates, were present here only in relatively low amounts. This is the first report where astaxanthin esters have been found as the major pigments in the taxon Dinoflagellata and largely over-expressed in comparison to the light-harvesting carotenoid peridinin. A plausible biogenetic route for the ketocarotenogenesis of T. sanguinea pigments is proposed.     

Discovery of a novel type of body scale in the marine dinoflagellate,Amphidinium cupulatisquama sp. nov. (Dinophyceae)

A new species of Amphidinium, A. cupulatisquama Tamura et Horiguchi, from sand samples from Ikei Island, Okinawa Prefecture in subtropical Japan, is described based on light, scanning and transmission electron microscopy and the partial sequencing of the large subunit rDNA gene. The species has a typical morphology for the genus, but is distinguished from previously described species by having a combination of the following characteristics: (i) a relatively large cell (over 30 µm in length); (ii) possessing an eyespot on the dorsal side of the cingulum; (iii) the longitudinal flagellum emerging from a point close to the cingulum; (iv) cell division taking place in the motile phase; and (v) possessing body scales. This is the third species of this genus to possess body scales. The body scales of A. cupulatisquama are uniform and cup‐shaped in side view and elliptical in face view. Their dimensions are 136.4 nm by 91.0 nm by 81.8 nm high. In side view, the scale is seen to have a thick lower half and a thin upper half. This scale type is very different from those of previously reported Amphidinium species (HG114 and HG115). The molecular tree indicated that A. cupulatisquama and the two other strains of body scale‐bearing Amphidinium are distantly related within the Amphidinium clade.     

Roscoffia minor sp. nov. (Peridiniales, Dinophyceae): A new, sand-dwelling, armored dinoflagellate from Hokkaido, Japan

A new, sand-dwelling, armored dinoflagellate, Roscoffia minor sp. nov., is described from Ishikari beach, Hokkaido, Japan. The dinoflagellate has been collected from sand samples taken both near the water's edge and further upshore (25 m from the water's edge at a depth of 1 m), indicating that it is a true sand-dwelling species. Roscoffia minor is heterotrophic and lacks both a chloroplast and an eye-spot. The cell consists of a flattened cap-shaped epitheca and a large hemispheroidal hypotheca, and it is quite different from cells of the typical armored dinoflagellates. The thecal plate formula is: Po, 3′, la, 5″, 3c, 3s, 5″, 1″″. Its distinct cell shape and the thecal plate arrangement indicate affinity to the monotypic genus Roscoffia. Roscoffia minor is distinguished from Roscoffia capitata, the type species, by its smaller size and the possession of a finger-like apical projection. The thecal arrangement of the epitheca is similar to those of the members of the family Podolampaceae, while the hypothecal arrangement is the same as that of members of the subfamily Diplopsalioideae (family Congruentidiaceae). The organism seems to be positioned somewhere intermediate between these two families, but the family to which this dinoflagellate should be affiliated could not be determined.     

Scrippsiella hexapraecingula sp. nov. (Dinophyceae), a tida pool dinoflagellate from the Northwest Pacific

Specimens of dinoflagellate collected in tide pools along the Pacific coast of central and southern Japan are described as a new species,Scrippsiella hexapraecingula Horiguchi et Chihara, of the Peridiniaceae (Class Dinophyceae). The plate formula is pp, x, 4′, 3a, 6″, 6c, 5‴, 2″" and, 5s, the same as that of other species ofScrippsiella, except in lacking one precingular plate. The genus must be emended, therefore, as having either six or seven precingular plates. This dinoflagellate migrates diurnally. In the morning motile cells are released from non-motile cells attached to the substrate and in the evening the motile cells swim down to settle on the bottom of the tide pool. Attached non-motile cells form either motile mono- or bispores. Sexual reproduction was not observed.     

‘You are inferior!’ Revisiting the expressivist argument

According to the expressivist argument the choice to use biotechnologies to prevent the birth of individuals with specific disabilities is an expression of disvalue for existing people with this disability. The argument has stirred a lively debate and has recently received renewed attention. This article starts with presenting the expressivist argument and its core elements. It then goes on to present and examine the counter‐arguments before it addresses some aspects that have gained surprisingly little attention. The analysis demonstrates that the expressivist argument has a wide range of underpinnings and that counter‐arguments tend to focus on only a few of these. It also reveals an important aspect that appears to have been ignored, i.e., that people do not select foetuses based on chromosomes or other biological traits, but based on characteristics of living persons with specific disabilities. This makes it more difficult to undermine the claim that negative selection of foetuses expresses a disvaluing of persons with such disabilities. It leaves the expressivist argument with a strong bite still.