Spring protistan communities in response to warming in the northeastern East China Sea

The northeastern East China Sea is a highly dynamic marine ecosystem influenced by seasonally varying water mass properties. However, despite being among the world's fastest-warming ocean, there has been limited investigation into the impacts of warming on protistan communities. We collected seawater from two stations (E42 and E46) with different natural protist communities and environmental attributes to investigate the acclimation of the two communities to artificially elevated temperatures (ambient T, +2, and +4 °C). Nutrient and Chl-a conditions reflected oceanographic differences, providing insights into protistan community dynamics. Notably, small-sized autotrophic protists prevailed in the phosphate-deficient E42 community, with mid-incubation heterotrophic conversions. Higher temperatures exacerbated the effects of the P deficiency on the E42 community. While the proportions of Bacillariophyta increased only in the nutrient-balanced E46 communities, those of mixotrophic dinoflagellates increased with elevated temperature, regardless of P deficiency, suggesting that mixotrophy likely aids adaptation in changing marine environments. In summary, the findings of this microcosm study illuminate the potential modulation of spring protistan communities in the northeastern East China Sea under anticipated future warming.

Morphology, phylogeny, and host range of the novel early-diverging oomycete Sirolpidium dinoletiferum sp. nov. parasitizing marine dinoflagellates

Oomycetes are fungus-like heterotrophic organisms with a broad environmental distribution, including marine, freshwater, and terrestrial habitats. They function as saprotrophs that use the remains of other organisms or as parasites of a variety of eukaryotes, including protists, diatoms, dinoflagellates, macroalgae, plants, fungi, animals, and even other oomycetes. Among the protist hosts, the taxonomy, morphology, and phylogenetic positions of the oomycete parasitoids of diatoms have been well studied; however, this information concerning the oomycete parasitoids of dinoflagellates is poorly understood. During intensive sampling along the east and west coasts of Korea in May and October 2019, a new species of oomycetes was discovered and two strains of the new parasitoid were successfully established in cultures. The new oomycete parasitoid penetrated the dinoflagellate host cell and developed to form a sporangium, which was very similar to the perkinsozoan parasitoids that infect marine dinoflagellates. The most distinctive morphological feature of the new parasitoid was a central large vacuole forming several long discharge tubes. The molecular phylogenetic tree inferred based on the small subunit (SSU) ribosomal DNA (rDNA) revealed that the new parasitoid forms a distinct branch unrelated to other described species belonging to early-diverging oomycetes. It clustered with species belonging to the genus Sirolpidium with strong support values in the cytochrome c oxidase subunit 2 (cox2) tree. Cross-infection experiments showed that infections by the new parasitoid occurred in only six genera belonging to dinoflagellates among the protists tested in this study. Based on the morphological and molecular data obtained in this study, we propose to introduce a new species, Sirolpidium dinoletiferum sp. nov., for this novel parasitoid, conservatively within the genus Sirolpidium.

Comparative biological traits of perkinsozoan parasitoids infecting marine dinoflagellates

The number of perkinsozoan parasitoid species known to infect dinoflagellates has increased to 11 over the last two decades. However, most of the current knowledge about the autecology of perkinsozoan parasitoids of dinoflagellates has derived from studies of one or two species, thereby making it difficult to directly compare their biological traits at the same time and even their potentials as biological control agents if they are to be exploited to mitigate harmful dinoflagellate blooms in the field. This study investigated total generation time, the number of zoospores produced per sporangium, zoospore size, swimming speed, parasite prevalence, zoospore survival and success rate, and host range and susceptibility for five perkinsozoan parasitoids. Four of the species (Dinovorax pyriformis, Tuberlatum coatsi, Parvilucifera infectans, and P. multicavata) were from the family Parviluciferaceae and one (Pararosarium dinoexitiosum) was from the family Pararosariidae, with dinoflagellate Alexandrium pacificum employed as a common host. Distinct differences in the biological traits of the five perkinsozoan parasitoid species were found, suggesting that the fitness of these parasitoids for the common host species differs. These results thus offer useful background information for the understanding of the impacts of parasitoids on the natural host population and for the design of numerical modeling including the host-parasitoid systems and biocontrol experiments in the field.

Evolutionary Dynamics and Lateral Gene Transfer in Raphidophyceae Plastid Genomes

The Raphidophyceae is an ecologically important eukaryotic lineage of primary producers and predators that inhabit marine and freshwater environments worldwide. These organisms are of great evolutionary interest because their plastids are the product of eukaryote-eukaryote endosymbiosis. To obtain deeper insight into the evolutionary history of raphidophycean plastids, we sequenced and analyzed the plastid genomes of three freshwater and three marine species. Our comparison of these genomes, together with the previously reported plastid genome of Heterosigma akashiwo, revealed unexpected variability in genome structure. Unlike the genomes of other analyzed species, the plastid genome of Gonyostomum semen was found to contain only a single rRNA operon, presumably due to the loss of genes from the inverted repeat (IR) region found in most plastid genomes. In contrast, the marine species Fibrocapsa japonica contains the largest IR region and overall plastid genome for any raphidophyte examined thus far, mainly due to the presence of four large gene-poor regions and foreign DNA. Two plastid genes, tyrC in F. japonica and He. akashiwo and serC in F. japonica, appear to have arisen via lateral gene transfer (LGT) from diatoms, and several raphidophyte open reading frames are demonstrably homologous to sequences in diatom plasmids and plastid genomes. A group II intron in the F. japonica psbB gene also appears to be derived by LGT. Our results provide important insights into the evolutionary history of raphidophyte plastid genomes via LGT from the plastids and plasmid DNAs of diatoms.

A Novel Parasitoid of Marine Dinoflagellates, Pararosarium dinoexitiosum gen. et sp. nov. (Perkinsozoa, Alveolata), Showing Characteristic Beaded Sporocytes

The phylum Perkinsozoa is known as an exclusively parasitic group within alveolates and is widely distributed in various aquatic environments from marine to freshwater environments. Nonetheless, their morphology, life cycle, the identity of the host, and physiological characteristics remain still poorly understood. During intensive sampling along the west coast of Korea in October and November 2017, a new parasitoid, which shares several characteristics with the extant families Perkinsidae and Parviluciferaceae, was discovered and three strains of the new parasitoid were successfully established in cultures. Cross-infection experiments showed that among the examined planktonic groups, only dinoflagellates were susceptible to the new parasitoid, with infections observed in species belonging to eight genera. Even though the new parasitoid shared many morphological and developmental characteristics with other Perkinsozoan parasites, it differed from them by its densely packed trophocyte structure without a large vacuole or hyaline material during the growth stage. These characteristics are common among Parviluciferaceae members. Furthermore, through palintomic extracellular sporogenesis, it produced characteristic interconnected sporocytes resembling a string of beads. Phylogenetic analyses based on the small subunit and large subunit ribosomal DNA sequences revealed that the new parasitoid was distantly related to the family Parviluciferaceae and was more closely related to the families Perkinsidae and Xcellidae. Morphological, ultrastructural, and molecular data on the new parasitoid raised the need to erect a new family, i.e., Pararosariidae, within the phylum Perkinsozoa with Pararosarium dinoexitiosum gen. et sp. nov. as the type species. The isolation and establishment in culture of the new parasitoid outside the family Parviluciferaceae in the present study would contribute to the better understanding of the diversity of Perkinsozoan parasites and provide useful material for comparisons to other parasite species in the further study.

Parasite-mediated increase in prey edibility in the predator-prey interaction of marine planktonic protists

In planktonic predator-prey interactions, predation pressure could be affected by several factors associated with prey, including cell size, shape, nutritional quality, presence of chemical deterrents, and movement behaviors. In addition, parasitism may also play an important role in predator-prey interaction by infecting one or both partners involved in the biological interaction. In this study, parasite mediation in predator-prey interactions of planktonic protists was addressed using model organisms commonly observed in temperate coastal environments, namely, a phototrophic dinoflagellate Akashiwo sanguinea as a potential host and prey, a heterotrophic dinoflagellate predator Luciella masanensis, and a dinoflagellates-infecting parasitoid Parvilucifera infectans. Parasite mediation permitted L. masanensis to exploit the prey A. sanguinea that the predator was otherwise unable to use or did not prefer. However, parasite-mediated exploitation seems to be dependent on the infection cycle of P. infectans. Although zoospores and mature sporangium produced from infected A. sanguinea were not ingested by the predator L. masanensis, both newly infected (i.e., cells that zoospores had just penetrated) and infected (those containing early to late trophocytes) A. sanguinea cells attracted numerous L. masanensis cells and were rapidly ingested by the predator, leading to the predator's positive growth. The results from mixed culture experiments of the three protists showed that the presence of P. infectans at low density led to co-occurrence of the three protists. Thus, the parasitoid seems to play the role of a mediator in either inedible prey- or predator-dominated environments, leading to co-occurrence of the three protists.

Distribution and genetic diversity of the toxic benthic dinoflagellate genus Ostreopsis in Korea

Species belonging to the toxic dinoflagellate genus Ostreopsis are widespread, occurring from tropical to temperate waters. As mainly benthic/epiphytic species, they would be expected to show distinct geographical patterns. In this study, ribosomal DNA (rDNA) sequences from partial nuclear LSU D8-D10, 5.8S, and ITS regions were determined for 169 isolates of Ostreopsis species collected from three coastal sites (i.e., Jeju Island, Chuja Island, and Pohang) within Korea. The phylogenetic tree inferred from the LSU rDNA D8-D10 sequences showed that Korean Ostreopsis species corresponded to either Ostreopsis sp. 1 or sp. 6, with Ostreopsis sp. 1 being relatively predominant regarding their distribution. While Ostreopsis sp. 1 occurred throughout all the three sampling sites within Korea, Ostreopsis sp. 6 was confined to the northern part of Jeju Island. When further investigated, the genetic diversity of Ostreopsis sp. 1 in Korea based on ITS sequences showed a total of 21 haplotypes. The presumed ancestral haplotype H3, was also present in the Japanese and Russian populations of Ostreopsis sp. 1. Although the overall demographic history of all the Korean populations of Ostreopsis sp. 1 could not be clearly identified, probably due to a mixture of different regional demographic patterns within Korea, each Ostreopsis sp. 1 population showed a characteristic demographic pattern at a regional scale. While the Jeju Island Ostreopsis sp. 1 population showed a signal in agreement with population equilibrium, the Chuja Island and Pohang Ostreopsis sp. 1 populations showed distribution patterns that are expected in a sudden population expansion model. The results from this study provide a basis for a better understanding of the distribution and genetic structure of the Asian Ostreopsis sp. 1 populations.

Asymptomatic Cerebral Vasoconstriction after Carotid Artery Stenting

BACKGROUND AND PURPOSE

Carotid artery stent placement is widely performed for treatment of carotid stenosis. The purpose of this study is to present our observations on cerebral vasoconstriction in ipsilateral anterior circulation during immediate poststenting angiography in patients with near-total occlusion of the proximal ICA.

MATERIALS AND METHODS

We retrospectively reviewed patient data from December 2008 to December 2018. There were 28 patients with carotid near-total occlusion. Two neuroradiologists reviewed the final cerebral angiographic finding of carotid artery stent placement to evaluate the presence of vasoconstriction or vasodilation.

RESULTS

A total of 28 patients with near-total occlusion (mean ± standard deviation age, 69.0 ± 6.5 years; 92.9% male) were analyzed. Ten patients showed vasoconstriction in the treated territory, and 18 patients did not show vasoconstriction after carotid artery stenting. There were no statistically significant differences in comorbidity, frequency of symptomatic lesions, antiplatelet medication, mean procedure time, and initial NIHSS and baseline modified Rankin scale scores between the 2 groups. However, vasoconstriction is more likely to happen in patients with isolated territory from the contralateral anterior and posterior circulation (66.7% in the isolated territory group and 12.5% in the not-isolated territory group; P < .05). No headache or neurologic deficit was noted in all 10 patients with cerebral vasoconstriction.

CONCLUSIONS

Cerebral vasoconstriction may occur after carotid artery stenting more frequently than expected. It occurs more frequently in patients with near-total occlusion and with isolation of the cerebral circulation. A large-scale study is necessary to assess the clinical implications of cerebral vasoconstriction after carotid artery stenting.

Unveiling the hidden genetic diversity and chloroplast type of marine benthic ciliate Mesodinium species

Ciliate Mesodinium species are commonly distributed in diverse aquatic systems worldwide. Among Mesodinium species, M. rubrum is closely associated with microbial food webs and red tide formation and is known to acquire chloroplasts from its cryptophyte prey for use in photosynthesis. For these reasons, Mesodinium has long received much attention in terms of ecophysiology and chloroplast evolution. Mesodinium cells are easily identifiable from other organisms owing to their unique morphology comprising two hemispheres, but a clear distinction among species is difficult under a microscope. Recent taxonomic studies of Mesodinium have been conducted largely in parallel with molecular sequence analysis, and the results have shown that the best-known planktonic M. rubrum in fact comprises eight genetic clades of a M. rubrum/M. major complex. However, unlike the planktonic Mesodinium species, little is known of the genetic diversity of benthic Mesodinium species, and to our knowledge, the present study is the first to explore this. A total of ten genetic clades, including two clades composed of M. chamaeleon and M. coatsi, were found in marine sandy sediments, eight of which were clades newly discovered through this study. We report the updated phylogenetic relationship within the genus Mesodinium comprising heterotrophic/mixotrophic as well as planktonic/benthic species. Furthermore, we unveiled the wide variety of chloroplasts of benthic Mesodinium, which were related to the green cryptophyte Chroomonas/Hemiselmis and the red cryptophyte Rhodomonas/Storeatula/Teleaulax groups.

Revisiting the taxonomy of the "Dinophysis acuminata complex'' (Dinophyta)'

Marine dinoflagellates of the genus Dinophysis are well known for producing diarrhetic shellfish poisoning (DSP) toxins and/or pectenotoxins which have a significant impact on public health as well as on marine aquaculture. Out of more than 80 Dinophysis species recorded so far, D. cf. acuminata is the most commonly observed in coastal areas worldwide. Due to their highly similar morphological features, however, an accurate discrimination of the various D. cf. acuminata species such as D. acuminata, D. ovum, and D. sacculus under light microscopy has proven to be a difficult task to accomplish. Hence, these species have thus far been referred to as the "Dinophysis acuminata complex". Recent studies showed a discrimination between local strains of D. acuminata and D. ovum from Galician, northwestern Spain, using the mitochondrial cox1 gene as a genetic marker in addition to commonly used morphological features such as size and contour of the large hypothecal plates, shape of the small cells formed as part of their polymorphic life-cycle, development of the left sulcal list and ribs, and length of the right sulcal list. In the present study, attempts were made to discriminate between D. acuminata and D. ovum following single-cell isolation of 54 "D. acuminata complex" collected from Korean coastal waters, based on the abovementioned traits. Morphological data showed that all the traits analyzed overlapped between the two species. The mitochondrial cox1 (cytochrome c oxidase subunit I) gene sequences of every isolate were also determined, but a genetic distinction between D. acuminata and D. ovum could not be confirmed, suggesting that the cox1 gene is not a suitable genetic marker for discrimination between the two species. The results of this study suggest that the morphological variations observed within the "D. acuminata complex" may have been caused by several factors (e.g. different geographical locations, seasonal changes, and different environmental conditions), and that D. acuminata and D. ovum may be the same species.

Growth and Chloroplast Replacement of the Benthic Mixotrophic Ciliate Mesodinium coatsi

While the ecophysiology of planktonic Mesodinium rubrum species complex has been relatively well studied, very little is known about that of benthic Mesodinium species. In this study, we examined the growth response of the benthic ciliate Mesodinium coatsi to different cryptophyte prey using an established culture of this species. M. coatsi was able to ingest all of the offered cryptophyte prey types, but not all cryptophytes supported its positive, sustained growth. While M. coatsi achieved sustained growth on all of the phycocyanin‐containing Chroomonas spp. it was offered, it showed different growth responses to the phycoerythrin‐containing cryptophytes Rhodomonas spp., Storeatula sp., and Teleaulax amphioxeia. M. coatsi was able to easily replace previously ingested prey chloroplasts with newly ingested ones within 4 d, irrespective of prey type, if cryptophyte prey were available. Once retained, the ingested prey chloroplasts seemed to be photosynthetically active. When fed, M. coatsi was capable of heterotrophic growth in darkness, but its growth was enhanced significantly in the light (14:10 h light:dark cycle), suggesting that photosynthesis by ingested prey chloroplast leads to a significant increase in the growth of M. coatsi. Our results expand the knowledge of autecology and ecophysiology of the benthic M. coatsi.

Different life cycle strategies of the dinoflagellates Fragilidium duplocampanaeforme and its prey Dinophysis acuminata may explain their different susceptibilities to the infection by the parasite Parvilucifera infectans

Some marine dinoflagellates form ecdysal cyst (=temporary cysts) as part of their life cycle or under unfavorable growth conditions. Whether the dinoflagellates form ecdysal cysts or not may influence susceptibility to parasitism. In this study, parasite prevalence relative to inoculum size of the parasitoid Parvilucifera infectans zoospores for two dinoflagellate hosts (i.e., Fragilidium duplocampanaeforme and Dinophysis acuminata), which have different life cycle strategies, was examined. Further, susceptibility of cysts to parasitism, encystment signal, duration of encystments, and effects of induced encystment on diel periodicity, using ecdysal cyst-forming F. duplocampanaeforme were explored. The percent hosts infected by P. infectans plotted as a function of inoculum size showed a sharp increase to a maximum in D. acuminata, but a gradual linear rise in F. duplocampanaeforme: while the parasite prevalence in D. acuminata increased to a maximum of 78.8 (±2.4%) by a zoospore:host ratio of 20:1, it in F. duplocampanaeforme only reached 8.9 (±0.3%), even at a zoospore:host ratio of 120:1. In F. duplocampanaeforme, infections were observed only in the vegetative cells and not observed in ecdysal cysts. When exposed to live, frozen, and sonicated zoospores and zoospore filtrate, F. duplocampanaeforme formed ecdysal cysts only when exposed to live zoospores, suggesting that temporary cyst formation in the dinoflagellate resulted from direct contact with zoospores. When the Parvilucifera zoospores attacked and struggled to penetrate F. duplocampanaeforme through its flagellar pore, the Fragilidium cell shed all thecal plates, forming a 'thecal cloud layer', in which the zoospores were caught and immobilized and thus could not penetrate anymore. The duration (35±1.8h) of ecdysal cysts induced with addition of zoospores was significantly longer than that (15±0.8h) of normally formed cysts (i.e., without addition of zoospores), thereby resulting in delayed growth as well as influencing the pattern of diel periodicity. The results from this study suggest that in addition to the classical predator-prey interaction and allelopathic interaction, parasitism and its accompanying defense can make the food web dynamics much more complicated than previously thought.

Feeding characteristics and molecular phylogeny of the thecate mixotrophic dinoflagellate Fragilidium mexicanum

Prey spectrum and feeding process of the mixotrophic thecate dinoflagellate Fragilidium mexicanum strain Fm-LOHABE01 were examined using a culture isolated from Masan Bay, Korea in 2011 during a summer bloom of the toxic dinoflagellate Alexandrium pacificum. The novel 18S and 28S rDNA sequences for F. mexicanum were also used to explore inter-species relationships within the genus Fragilidium. The F. mexicanum fed on species belonging to four dinoflagellate genera (i.e., Alexandrium, Ceratium, Heterocapsa, and Scrippsiella) when separately offered a variety of prey, including dinoflagellates, raphidophytes, cryptophytes, and a ciliate. In addition, F. mexicanum displayed different levels of feeding frequency for prey species of Alexandrium. While F. mexicanum consistently fed on A. catenella and A. pacificum, feeding on A. affine was rarely observed. The F. mexicanum ingested prey by direct engulfment through the sulcus, after capturing the prey by a tow filament. Phylogenetic analyses of 18S and 28S rDNA datasets demonstrated that Fragilidium sequences formed a monophyletic group with high statistical supports and diverged into four distinct clades. The F. mexicanum formed a separate clade with Fragilidium sp. EUSK D from Angola and Korean isolate of F. fissile with very strong supports.

The fate of cryptophyte cell organelles in the ciliate Mesodinium cf. rubrum subjected to starvation

Mesodinium rubrum Lohmann is a mixotrophic ciliate and one of the best studied species exhibiting acquired phototrophy. To investigate the fate of cryptophyte organelles in the ciliate subjected to starvation, we conducted ultrastructural studies of a Korean strain of M. cf. rubrum during a 10 week starvation experiments. Ingested cells of the cryptophyte Teleaulax amphioxeia were first enveloped by ciliate membrane, and then prey organelles, including ejectisomes, flagella, basal bodies and flagellar roots, were digested. Over time, prey nuclei protruded into the cytoplasm of the ciliate, their size and volume increased, and their number decreased, suggesting that the cryptophyte nuclei likely fused with each other in the ciliate cytoplasm. At 4 weeks of starvation, M. cf. rubrum cells without cryptophyte nuclei started to appear. At 10 weeks of starvation, only two M. cf. rubrum cells still possessing a cryptophyte nucleus had relatively intact chloroplast-mitochondria complexes (CMCs), while M. cf. rubrum cells without cryptophyte nuclei had a few damaged CMCs. This is the first ultrastructural study demonstrating that cryptophyte nuclei undergo a dramatic change inside M. cf. rubrum in terms of size, shape, and number following their acquisition.

Effect of the endoparasite Amoebophrya sp. on toxin content and composition in the paralytic shellfish poisoning dinoflagellate Alexandrium fundyense (Dinophyceae)

Members of the Amoebophrya ceratii complex are endoparasitic dinoflagellates that parasitize a number of their dinoflagellate relatives, including toxic and/or harmful algal bloom-forming species. Despite many studies on the occurrence, prevalence, biology and molecular phylogeny of Amoebophrya spp., little attention has been given to toxin dynamics of host population following parasitism. Using Amoebophrya sp. infecting the paralytic shellfish toxin (PSP)-producing dinoflagellate Alexandrium fundyense, we addressed the following questions: (1) does parasitism by Amoebophrya sp. alter toxin content and toxin profiles of the dinoflagellate A. fundyense over the infection cycle? and (2) do parasite dinospores produced at the end of the infection cycle retain host toxins and thus potentially act as a vector to convey PSP toxin through the marine microbial food-web? Toxin time-course experiments showed that the PSP toxin contents did not vary significantly over the infection cycle, but mean toxin content for infected cultures was significantly higher than that for uninfected cultures. Host toxins were not detected in the free-living, dinospore stage of the parasite. Therefore, our results indicate that Amoebophrya sp. does not function as a vector for transferring PSP toxins to higher trophic levels. Rather, Amoebophrya infections appear to play an important role in maintaining healthy ecosystems by transforming potent toxins-producing dinoflagellates into non-toxic dinospores, representing "edible food" for consumers of the marine microbial food-web during toxic algal bloom event.

Paulinella longichromatophora sp. nov., a New Marine Photosynthetic Testate Amoeba Containing a Chromatophore

The freshwater testate filose amoeba Paulinella chromatophora is the sole species in the genus to have plastids, usually termed "chromatophores", of a Synechococcus/Prochlorococcus-like cyanobacterial origin. Here, we report a new marine phototrophic species, Paulinella longichromatophora sp. nov., using light and electron microscopy and molecular data. This new species contains two blue-green U-shaped chromatophores reaching up to 40 μm in total length. Further, the new Paulinella species is characterized by having five oral scales surrounding the pseudostomal aperture. All trees generated using three nuclear rDNA datasets (18S rDNA, 28S rDNA, and the concatenated 18S + 28S rDNA) demonstrated that three photosynthetic Paulinella species (two freshwater species, P. chromatophora and Paulinella strain FK01, and one marine species, P. longichromatophora) congruently formed a monophyletic group with strong support (≥ 90% of ML and ≥ 0.90 of PP), but their relationship to each other within the clade remained unresolved in all trees. P. longichromatophora, nevertheless, clustered consistently together with Paulinella strain FK01 with very low support, but the clade received strong support in plastid phylogenies. Phylogenetic analyses inferred from plastid-encoded 16S rDNA and a concatenated dataset of plastid 16S+23S rDNA demonstrated that chromatophores of all photosynthetic Paulinella species were monophyletic. The monophyletic group fell within a cyanobacteria clade having a close relationship to an α-cyanobacterial clade containing Prochlorococcus and Synechococcus species with very robust support (100% of ML and 1.0 of PP). Additionally, phylogenetic analyses of nuclear 18S rDNA and plastid 16S rDNA suggested divergent evolution within the photosynthetic Paulinella population after a single acquisition of the chromatophore. After the single acquisition of the chromatophore, ancestral photosynthetic Paulinella appears to have diverged into at least two distinct clades, one containing the marine P. longichromatophora and freshwater Paulinella strain FK01, the other P. chromatophora CCAC 0185.

Do All Dinoflagellates have an Extranuclear Spindle?

The syndinean dinoflagellates are a diverse assemblage of alveolate endoparasites that branch basal to the core dinoflagellates. Because of their phylogenetic position, the syndineans are considered key model microorganisms in understanding early evolution in the dinoflagellates. Closed mitosis with an extranuclear spindle that traverses the nucleus in cytoplasmic grooves or tunnels is viewed as one of the morphological features shared by syndinean and core dinoflagellates. Here we describe nuclear morphology and mitosis in the syndinean dinoflagellate Amoebophrya sp. from Akashiwo sanguinea, a member of the A. ceratii complex, as revealed by protargol silver impregnation, DNA specific fluorochromes, and transmission electron microscopy. Our observations show that not all species classified as dinoflagellates have an extranuclear spindle. In Amoebophrya sp. from A. sanguinea, an extranuclear microtubule cylinder located in a depression in the nuclear surface during interphase moves into the nucleoplasm via sequential membrane fusion events and develops into an entirely intranuclear spindle. Results suggest that the intranuclear spindle of Amoebophrya spp. may have evolved from an ancestral extranuclear spindle and indicate the need for taxonomic revision of the Amoebophryidae.

The effect of starvation on plastid number and photosynthetic performance in the kleptoplastidic dinoflagellate Amylax triacantha

The dinoflagellate Amylax triacantha is known to retain plastids of cryptophyte origin by engulfing the mixotrophic ciliate Mesodinium rubrum, itself a consumer of cryptophytes. However, there is no information on the fate of the prey's organelles and the photosynthetic performance of the newly retained plastids in A. triacantha. In this study, we conducted a starvation experiment to observe the intracellular organization of the prey's organelles and temporal changes in the photosynthetic efficiency of acquired plastids in A. triacantha. The ultrastructural observations revealed that while the chloroplast-mitochondria complexes and nucleus of cryptophyte were retained by A. triacantha, other ciliate organelles were digested in food vacuoles. Acquired plastids were retained in A. triacantha for about 1 mo and showed photosynthetic activities for about 18 d when measured by a pulse-amplitude modulation fluorometer.

A dinoflagellate Amylax triacantha with plastids of the cryptophyte origin: phylogeny, feeding mechanism, and growth and grazing responses

The gonyaulacalean dinoflagellates Amylax spp. were recently found to contain plastids of the cryptophyte origin, more specifically of Teleaulax amphioxeia. However, not only how the dinoflagellates get the plastids of the cryptophyte origin is unknown but also their ecophysiology, including growth and feeding responses as functions of both light and prey concentration, remain unknown. Here, we report the establishment of Amylax triacantha in culture, its feeding mechanism, and its growth rate using the ciliate prey Mesodinium rubrum (= Myrionecta rubra) in light and dark, and growth and grazing responses to prey concentration and light intensity. The strain established in culture in this study was assigned to A. triacantha, based on morphological characteristics (particularly, a prominent apical horn and three antapical spines) and nuclear SSU and LSU rDNA sequences. Amylax triacantha grew well in laboratory culture when supplied with the marine mixotrophic ciliate M. rubrum as prey, reaching densities of over 7.5 × 10(3)  cells/ml. Amylax triacantha captured its prey using a tow filament, and then ingested the whole prey by direct engulfment through the sulcus. The dinoflagellate was able to grow heterotrophically in the dark, but the growth rate was approximately two times lower than in the light. Although mixotrophic growth rates of A. triacantha increased sharply with mean prey concentrations, with maximum growth rate being 0.68/d, phototrophic growth (i.e. growth in the absence of prey) was -0.08/d. The maximum ingestion rate was 2.54 ng C/Amylax/d (5.9 cells/Amylax/d). Growth rate also increased with increasing light intensity, but the effect was evident only when prey was supplied. Increased growth with increasing light intensity was accompanied by a corresponding increase in ingestion. In mixed cultures of two predators, A. triacantha and Dinophysis acuminata, with M. rubrum as prey, A. triacantha outgrew D. acuminata due to its approximately three times higher growth rate, suggesting that it can outcompete D. acuminata. Our results would help better understand the ecophysiology of dinoflagellates retaining foreign plastids.

DINOPHYSIS CAUDATA (DINOPHYCEAE) SEQUESTERS AND RETAINS PLASTIDS FROM THE MIXOTROPHIC CILIATE PREY MESODINIUM RUBRUM(1)

"Phototrophic"Dinophysis Ehrenberg species are well known to have chloroplasts of a cryptophyte origin, more specifically of the cryptophyte genus complex Teleaulax/Geminigera. Nonetheless, whether chloroplasts of "phototrophic"Dinophysis are permanent plastids or periodically derived kleptoplastids (stolen chloroplasts) has not been confirmed. Indeed, molecular sequence data and ultrastructural data lead to contradictory interpretations about the status of Dinophysis plastids. Here, we used established cultures of D. caudata strain DC-LOHABE01 and M. rubrum strain MR-MAL01 to address the status of Dinophysis plastids. Our approach was to experimentally generate D. caudata with "green" plastids and then follow the ingestion and fate of "reddish-brown" prey plastids using light microscopy, time-lapse videography, and single-cell TEM. Our results for D. caudata resolve the apparent discrepancy between morphological and molecular data by showing that plastids acquired when feeding on M. rubrum are structurally modified and retained as stellate compound chloroplasts characteristic of Dinophysis species.

Pretreatment of polyethylene terephthalate substrate for the growth of Ga-doped ZnO thin film

The effect of the pretreatment of polyethylene terephthalate (PET) substrate on the growth of transparent conducting Ga-doped ZnO (GZO) thin film was investigated. Because of its high gas and moisture absorption and easy gas permeation, PET substrate was annealed at 100 degrees C in a vacuum chamber prior to the sputtering growth of GZO thin film for the outgassing of impurity gases. GZO thin film was deposited on the pretreated PET substrate by rf-magnetron sputtering and significantly improved electrical properties of GZO thin film was achieved. Electrical and structural characterizations of the GZO thin films were carried out by 4-point probe, Hall measurement, and scanning electron microscopy, and the effects of the pretreatment on the improved properties of GZO thin films were discussed. This result is not only useful to PET substrate, but also could be applicable to other plastic substrates which inevitably containing the moisture and impurity gases.

Expression of transforming growth factor-beta1 and hypoxia-inducible factor-1alpha in renal transplantation

Chronic allograft nephropathy (CAN) includes pathologic changes of interstitial fibrosis, tubular atrophy, and fibrous intimal thickening. Transforming growth factor (TGF)-beta1 is a fibrogenic cytokine involved in renal allograft fibrosis. Hypoxia-inducible factor (HIF)-1alpha is induced as an adaptive response to hypoxia triggering the production of fibrogenic cytokines such as TGF-beta1. Between January 1995 and February 2005, we performed 71 renal allograft biopsies in 61 recipients. Immunohistochemical studies were performed with an immunoperoxidase technique using as the primary antibody either a rabbit anti-human TGF-beta1 polyclonal or a mouse anti-human HIF-1alpha monoclonal reagent. The glomerular TGF-beta1 expression in recipients diagnosed with glomerulonephritis was significantly greater than other pathologic groups (P < .05), and the glomerular TGF-beta1 expression in the heavy proteinuria group (> or =2.5 g/d) was significantly greater than the low proteinuria group (<1.0 g/d; P < .05). The tubular and interstitial TGF-beta1 and HIF-1alpha expressions in CAN were greater than in other groups (P < .05). The tubular TGF-beta1 expression among the graft loss group was significantly greater than the graft function group (P < .05).

PLASTID DYNAMICS DURING SURVIVAL OF DINOPHYSIS CAUDATA WITHOUT ITS CILIATE PREY(1)

To survive, the marine dinoflagellate Dinophysis caudata Saville-Kent must feed on the plastidic ciliate Myrionecta rubra (=Mesodinium rubrum), itself a consumer of cryptophytes. Whether D. caudata has its own permanent chloroplasts or retains plastids from its ciliate prey, however, remains unresolved. Further, how long D. caudata plastids (or kleptoplastids) persist and remain photosynthetically active in the absence of prey remains unknown. We addressed those issues here, using the first established culture of D. caudata. Phylogenetic analyses of the plastid 16S rRNA and psbA gene sequences directly from the three organisms (D. caudata, M. rubra, and a cryptophyte) revealed that the sequences of both genes from the three organisms are almost identical to each other, supporting that the plastids of D. caudata are kleptoplastids. A 3-month starvation experiment revealed that D. caudata can remain photosynthetically active for ∼2 months when not supplied with prey. D. caudata cells starved for more than 2 months continued to keep the plastid 16S rRNA gene but lost the photosynthesis-related genes (i.e., psaA and psbA genes). When the prey was available again, however, D. caudata cells starved for more than 2 months were able to reacquire plastids and slowly resumed photosynthetic activity. Taken all together, the results indicate that the nature of the relationship between D. caudata and its plastids is not that of permanent cellular acquisitions. D. caudata is an intriguing protist that would represent an interesting evolutionary adaptation with regard to photosynthesis as well as help us to better understand plastid evolution in eukaryotes.

Parasites and Phytoplankton, with Special Emphasis on Dinoflagellate Infections1

Planktonic members of most algal groups are known to harbor intracellular symbionts, including viruses, bacteria, fungi, and protozoa. Among the dinoflagellates, viral and bacterial associations were recognized a quarter century ago, yet their impact on host populations remains largely unresolved. By contrast, fungal and protozoan infections of dinoflagellates are well documented and generally viewed as playing major roles in host population dynamics. Our understanding of fungal parasites is largely based on studies for freshwater diatoms and dinoflagellates, although fungal infections are known for some marine phytoplankton. In freshwater systems, fungal chytrids have been linked to mass mortalities of host organisms, suppression or retardation of phytoplankton blooms, and selective effects on species composition leading to successional changes in plankton communities. Parasitic dinoflagellates of the genus Amoebophrya and the newly described Perkinsozoa, Parvilucifera infectans, are widely distributed in coastal waters of the world where they commonly infect photosynthetic and heterotrophic dinoflagellates. Recent work indicates that these parasites can have significant impacts on host physiology, behavior, and bloom dynamics. Thus, parasitism needs to be carefully considered in developing concepts about plankton dynamics and the flow of material in marine food webs.

Feeding by the Heterotrophic Dinoflagellate Oxyrrhis marina on the Red-Tide Raphidophyte Heterosigma akashiwo: a Potential Biological Method to Control Red Tides Using Mass-Cultured Grazers

As part of the development of a method to control the outbreak and persistence of red tides using mass-cultured heterotrophic protist grazers, we measured the growth and ingestion rates of cultured Oxyrrhis marina (a heterotrophic dinoflagellate) on cultured Heterosigma akashiwo (a raphidophyte) in bottles in the laboratory and in mesocosms (ca. 60 liter) in nature, and those of the cultured grazer on natural populations of the red-tide organism in mesocosms set up in nature. In the bottle incubation, specific growth rates of O. marina increased rapidly with increasing concentration of cultured prey up to ca. 950 ng C ml(-1) (equivalent to 9,500 cells ml(-1)), but were saturated at higher concentrations. Maximum specific growth rate (mumax), KGR (prey concentration sustaining 0.5 mumax) and threshold prey concentration of O. marina on H. akashiwo were 1.43 d(-1), 104 ng C ml(-1), and 8.0 ng C ml(-1), respectively. Maximum ingestion and clearance rates of O. marina were 1.27 ng C grazer(-1) d(-1) and 0.3 microl grazer(-1) h(-1), respectively. Cultured O. marina grew well effectively reducing cultured and natural populations of H. akashiwo down to a very low concentration within 3 d in the mesocosms. The growth and ingestion rates of cultured O. marina on natural populations of H. akashiwo in the mesocosms were 39% and 40%, respectively, of those calculated based on the results from the bottle incubation in the laboratory, while growth and ingestion rates of cultured O. marina on cultured H. akashiwo in the mesocosms were 55% and 36%, respectively. Calculated grazing impact by O. marina on natural populations of H. akashiwo suggests that O. marina cultured on a large scale could be used for controlling red tides by H. akashiwo near aquaculture farms that are located in small ponds, lagoons, semi-enclosed bays, and large land-aqua tanks to which fresh seawater should be frequently supplied.

Nutrient removal processes for low strength wastewater

For nutrient removal from low strength wastewater, biological nutrient removal (BNR) processes available at present are not efficient due to the shortage of organic carbon. By using the carbon source obtained from the degradation of return sludge, it was attempted to enhance the efficiency of denitrification and phosphorus release. Based on its degradation mechanism, the ENR (Endogenous Nitrate Respiration) process was developed and compared with the conventional A2/O (Anaerobic/Anoxic/Aerobic), MUCT (Modified University of Cape Town) processes. In the experiment, the specific phosphorus release rates of A2/O, MUCT, and ENR processes were 0.8, 2.3, and 2.6 mg PO1-P g1 MLVSS-h. As the nitrate concentration decreased below 3.0 mg NO1-N l1 due to the endogenous nitrate respiration, the effluent nitrate of the ENR process was lower than the A2/O process and the MUCT process by 25% and 10% while the phosphorus removal efficiencies increased by 15% and 6%, respectively. It was found that the ENR process was an effective and economical alternative for removing nutrient from low strength wastewater

Effect of ouabain on relaxation induced by cromakalim in human and canine mesenteric arteries

We investigated the effect of cromakalim, a K+ channel opener, that activates indirectly the Na(+)-K+ pump, in association with increased K+ conductance in the mesenteric arteries. In 65% of human mesenteric arteries tested, the concentration-dependent relaxation curves for cromakalim were biphasic: the low concentration (< 10(-7) M) effect was preferentially inhibited by ouabain, whereas the higher concentration effect was significantly inhibited by glibenclamide. In branches of canine mesenteric artery, the cromakalim-induced relaxation was inhibited by pretreatment with ouabain (1 microM) as well as by glibenclamide (1 microM). The reduction in contraction of human and canine mesenteric arterial strips caused by cromakalim was totally reversed by pretreatment with ouabain (1 microM) or glibenclamide (1 microM). On the other hand, in canine mesenteric artery, cromakalim caused a significant stimulation of 22Na+ influx and ouabain-sensitive 86Rb+ uptake in association with increased 86Rb+ efflux, all of which were inhibited by glibenclamide (1 microM). Thus, it is suggested that cromakalim possesses the additional property to stimulate the Na(+)-K+ pump through an elevation in intracellular Na+, resulting in strong relaxation of blood vessels.

Pseudoexfoliation syndrome--case report and review of clinical features

Pseudoexfoliation syndrome is characterized by the presence of gray-white flakes on the pupillary borders and anterior lens capsule, increased trabecular meshwork pigmentation, and association with glaucoma. We describe 3 patients with this syndrome seen at Asan Meidcal Center Department of Ophthalmology in 1989, and we focus on their clinical features and management. We believe that patients with this syndrome are not as rare in Korea as has been thought, judging by scant report of cases in the past.

Structure of 3-(4-methoxyphenyl)-4-phenyl-4H-1,2,4-triazole

C15H13N3O, Mr = 251.29, triclinic, P-1, a = 9.294, (1), b = 11.394 (4), c = 13.375 (2) A, a = 103.60 (2), beta = 96.82 (1), gamma = 107.47 (2) degrees, V = 1285 A3, Z = 4, Dx = 1.30 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.92 cm-1, F(000) = 528, T = 295 K, final R = 0.045 for 2311 observed [Fo greater than or equal to 5 sigma(Fo)] reflections. There are two molecules in the asymmetric unit. The triazole rings are planar with the phenyl substituents twisted with respect to these planes. The two molecules in the asymmetric unit are different in the relative twists of the phenyl groups.