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1.
Chemosphere ; 238: 124661, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31472350

RESUMO

Toxicities of the marine algae Alexandrium minutum and its excreted gonyautoxins (GTXs) to the marine crustacean Artemia salina were investigated. Mortality was observed for neither larvae nor adult A. salina exposed to A. minutum at a density of 5000 cells/mL or 0.5 µM GTX2/3. After exposure, the full transcriptome of adult A. salina was assembled and functionally annotated. A total of 599,286 transcripts were obtained, which were clustered into 515,196 unigenes. Results of the transcriptional effect level index revealed that direct exposure to the toxic algae A. minutum caused greater alterations in the transcriptome than did exposure to the extracellular product GTX2/3. Mechanisms of effects were different between exposure of A. salina to A. minutum cells or GTX2/3. Exposure to A. minutum modulated formation of the ribonucleoprotein complex and metabolism of amino acids and lipids in A. salina. Exposure to GTX2/3 exposure inhibited expression of genes related to metabolism of chitin, which might result in disruption of molting process or disturbed sheath morphogenesis. Overall, effects on transcription observed in this study represent the first report based on application of next generation sequencing techniques to investigate the transcriptomic response of A. salina exposed to an environmentally realistic level of A. minutum or GTX2/3.


Assuntos
Artemia/genética , Saxitoxina/análogos & derivados , Transcriptoma/efeitos dos fármacos , Animais , Artemia/fisiologia , Quitina/genética , Quitina/metabolismo , Dinoflagelados/citologia , Dinoflagelados/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Saxitoxina/farmacologia , Saxitoxina/toxicidade
2.
Eur J Protistol ; 71: 125638, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31550628

RESUMO

Pseudothecadinium campbellii, a phototrophic, thecate, marine benthic species, has been found in the Sea of Japan, Russia. The morphological description of the species has been emended, and the thecal tabulation pattern is now APC 4' 2a 4″ 6c 6 s 5‴ 1⁗. Our study indicates that P. campbellii is related to Thecadinium kofoidii and Thecadiniopsis tasmanica, based on a unique morphological feature: incomplete precingular plate series. Previously, molecular data was not available for the taxa, and thus the phylogenetic position of P. campbellii within the Dinophyceae remained obscure. In this study, analyses of the rRNA gene sequences (partial 18S and 28S) revealed that unexpectedly, P. campbellii is most closely related to Halostylodinium arenarium. It formed a common clade with the Thecadinium sensu stricto clade comprising T. kofoidii and T. pseudokofoidii. This clade was placed within the order Gonyaulacales. However, almost no similarity in morphology was found between the two genetically closest species. In addition, they have different lifestyles: unlike P. campbellii, the nonmotile stage is dominant in the life cycle of H. arenarium. It has been shown that other genetically similar species (T. kofoidii, T. pseudokofoidii, T. yashimaense) exhibited some morphological features that unite them with gonyaulacoids.


Assuntos
Dinoflagelados/classificação , Filogenia , DNA Ribossômico/genética , Dinoflagelados/citologia , Dinoflagelados/genética , Federação Russa , Especificidade da Espécie
3.
Protist ; 170(5): 125680, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31563792

RESUMO

Marine unarmored dinoflagellates in the family Kareniaceae are known to possess chloroplasts of haptophyte origin, which contain fucoxanthin and its derivatives as major carotenoids, and lack peridinin. In the present study, the first species with the peridinin-type chloroplast in this family, Gertia stigmatica gen. et sp. nov., is described on the basis of ultrastructure, photosynthetic pigment composition, and molecular phylogeny inferred from nucleus- and chloroplast-encoded genes. Cells of G. stigmatica were small and harboring a chloroplast with an eyespot and two pyrenoids. The apical structure complex was straight, similar to Karenia and Karlodinium. Under transmission electron microscopy, the chloroplast was surrounded by two membranes, and the eyespot was composed of a single layer of osmiophilic globules (eyespot type A); this was never previously reported from the Kareniaceae. High performance liquid chromatography demonstrated the chloroplast contains peridinin, and neither fucoxanthin nor 19'-acyloxyfucoxanthins was identified. A phylogeny based on nucleus-encoded rDNAs suggested a position of G. stigmatica in the Kareniaceae, but not clustered within the previously described genera, i.e., Karenia, Karlodinium and Takayama. A phylogeny of chloroplast-encoded psbA, psbC and psbD indicated the chloroplast is of peridinin-type typical of dinoflagellates, but the most related species remains unclear.


Assuntos
Organismos Aquáticos , Carotenoides , Cloroplastos , Dinoflagelados/classificação , Organismos Aquáticos/classificação , Organismos Aquáticos/citologia , Organismos Aquáticos/metabolismo , Carotenoides/metabolismo , Cloroplastos/classificação , Cloroplastos/metabolismo , Dinoflagelados/citologia , Dinoflagelados/metabolismo , Especificidade da Espécie
4.
Nature ; 568(7750): 103-107, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30944491

RESUMO

Apicomplexa is a group of obligate intracellular parasites that includes the causative agents of human diseases such as malaria and toxoplasmosis. Apicomplexans evolved from free-living phototrophic ancestors, but how this transition to parasitism occurred remains unknown. One potential clue lies in coral reefs, of which environmental DNA surveys have uncovered several lineages of uncharacterized basally branching apicomplexans1,2. Reef-building corals have a well-studied symbiotic relationship with photosynthetic Symbiodiniaceae dinoflagellates (for example, Symbiodinium3), but the identification of other key microbial symbionts of corals has proven to be challenging4,5. Here we use community surveys, genomics and microscopy analyses to identify an apicomplexan lineage-which we informally name 'corallicolids'-that was found at a high prevalence (over 80% of samples, 70% of genera) across all major groups of corals. Corallicolids were the second most abundant coral-associated microeukaryotes after the Symbiodiniaceae, and are therefore core members of the coral microbiome. In situ fluorescence and electron microscopy confirmed that corallicolids live intracellularly within the tissues of the coral gastric cavity, and that they possess apicomplexan ultrastructural features. We sequenced the genome of the corallicolid plastid, which lacked all genes for photosystem proteins; this indicates that corallicolids probably contain a non-photosynthetic plastid (an apicoplast6). However, the corallicolid plastid differs from all other known apicoplasts because it retains the four ancestral genes that are involved in chlorophyll biosynthesis. Corallicolids thus share characteristics with both their parasitic and their free-living relatives, which suggests that they are evolutionary intermediates and implies the existence of a unique biochemistry during the transition from phototrophy to parasitism.


Assuntos
Antozoários/parasitologia , Apicomplexa/genética , Apicomplexa/metabolismo , Clorofila/biossíntese , Genes de Protozoários/genética , Filogenia , Animais , Apicomplexa/citologia , Recifes de Corais , Dinoflagelados/citologia , Dinoflagelados/genética , Dinoflagelados/metabolismo , Genoma de Protozoário/genética , Fotossíntese , Plastídeos/genética , Simbiose
5.
Eur J Protistol ; 68: 37-47, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30708241

RESUMO

Changes in salinity are known to alter the morphology of protists, and we hypothesized that these changes subsequently alter also the predatory behavior of the dinoflagellate Oxyrrhis marina. Oxyrrhis was grown in media of 33, 25, 20, and 10% of the regular salinity of f/2 medium (31-32‰). In all cases, the cells discharged trichocysts and swelled. Cell surfaces and volumes increased with decreasing salinity, such that cell surface area at least doubled at 10% and the cell volume increased approximately fourfold. After 1 h, the cells started to regain their regular shape, which was almost completed after 24 h. Oxyrrhis immediately regained its regular shape when culture medium was added 5-10 min after the osmotic stress. When incubated with Pyramimonas grossii as prey, those short-term stressed cells showed no significant different prey uptake in comparison to non-stressed cells. In contrast, 24 h after the addition of prey, short-term stressed Oxyrrhis cells had, with weak statistical significance, more Pyramimonas cells engulfed than non-stressed cells. These results indicated that (1) trichocysts were most likely not involved in prey capture and (2) salinity-stressed Oxyrrhis either enhanced its capability to capture more prey, or its digestion apparatus was hampered.


Assuntos
Dinoflagelados/citologia , Dinoflagelados/fisiologia , Comportamento Predatório , Salinidade , Animais , Dinoflagelados/efeitos dos fármacos , Comportamento Predatório/efeitos dos fármacos , Cloreto de Sódio/farmacologia
6.
Protist ; 170(1): 82-103, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30797136

RESUMO

Perkinsozoa is an exclusively parasitic group within the alveolates and infections have been reported from various organisms, including marine shellfish, marine dinoflagellates, freshwater cryptophytes, and tadpoles. Despite its high abundance and great genetic diversity revealed by recent environmental rDNA sequencing studies, Perkinsozoa biodiversity remains poorly understood. During the intensive samplings in Korean coastal waters during June 2017, a new parasitoid of dinoflagellates was detected and was successfully established in culture. The new parasitoid was most characterized by the presence of two to four dome-shaped, short germ tubes in the sporangium. The opened germ tubes were biconvex lens-shaped in the top view and were characterized by numerous wrinkles around their openings. Phylogenetic analyses based on the concatenated SSU and LSU rDNA sequences revealed that the new parasitoid was included in the family Parviluciferaceae, in which all members were comprised of two separate clades, one containing Parvilucifera species (P. infectans, P. corolla, and P. rostrata), and the other containing Dinovorax pyriformis, Snorkelia spp., and the new parasitoid from this study. Based on morphological, ultrastructural, and molecular data, we propose to erect a new genus and species, Tuberlatum coatsi gen. n., sp. n., from the new parasitoid found in this study. Further, we examined and discussed the validity of some diagnostic characteristics reported for parasitoids in the family Parviluciferaceae at both the genus and species levels.


Assuntos
Alveolados/classificação , Alveolados/fisiologia , Dinoflagelados/parasitologia , Alveolados/citologia , Alveolados/ultraestrutura , Dinoflagelados/citologia , Dinoflagelados/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Filogenia , RNA de Algas/análise , RNA de Protozoário/análise , República da Coreia , Análise de Sequência de RNA
7.
Toxins (Basel) ; 10(12)2018 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-30477142

RESUMO

Causative species of Harmful Algal Bloom (HAB) and toxins in commercially exploited molluscan shellfish species are monitored weekly from four classified shellfish production areas in Perú (three in the north and one in the south). Okadaic acid (OA) and pectenotoxins (PTXs) were detected in hand-picked cells of Dinophysis (D. acuminata-complex and D. caudata) and in scallops (Argopecten purpuratus), the most important commercial bivalve species in Perú. LC-MS analyses revealed two different toxin profiles associated with species of the D. acuminata-complex: (a) one with OA (0.3⁻8.0 pg cell-1) and PTX2 (1.5⁻11.1 pg cell-1) and (b) another with only PTX2 which included populations with different toxin cell quota (9.3⁻9.6 pg cell-1 and 5.8⁻9.2 pg cell-1). Toxin results suggest the likely presence of two morphotypes of the D. acuminata-complex in the north, and only one of them in the south. Likewise, shellfish toxin analyses revealed the presence of PTX2 in all samples (10.3⁻34.8 µg kg-1), but OA (7.7⁻15.2 µg kg-1) only in the northern samples. Toxin levels were below the regulatory limits established for diarrhetic shellfish poisoning (DSP) and PTXs (160 µg OA kg-1) in Perú, in all samples analyzed. This is the first report confirming the presence of OA and PTX in Dinophysis cells and in shellfish from Peruvian coastal waters.


Assuntos
Dinoflagelados/citologia , Furanos/análise , Toxinas Marinhas/análise , Ácido Okadáico/análise , Pectinidae/química , Piranos/análise , Animais , Monitoramento Ambiental , Contaminação de Alimentos/análise , Peru
8.
J Phycol ; 54(6): 923-928, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30276824

RESUMO

The planktonic phototrophic dinoflagellate Gonyaulax whaseongensis sp. nov., isolated from coastal waters of western Korea, was described from living and fixed cells under light and scanning electron microscopy, and its rDNA was sequenced. Gonyaulax whaseongensis had a plate formula of 2pr, 4', 6'', 6c, 6''', 1p, and 1'''' with S-type ventral organization like the other species in the genus. However, this dinoflagellate had a narrow cingulum (ca. 2.6 µm), small displacement of the cingulum, slight overhang and steep angle between the ends of the cingulum, quadrangular sixth precingular plate, reticulated cell surface without longitudinal lines or ridges, and two unequal antapical spines, together which distinguish this from all other reported Gonyaulax species. In addition, the SSU and LSU rDNA sequences were 8%-12% and 11%-24%, respectively, different from those of Gonyaulax polygramma, Gonyaulax spinifera, Gonyaulax fragilis, Gonyaulax membranacea, and Gonyaulax digitale, the putatively closest related species in the phylogenetic analysis.


Assuntos
Dinoflagelados/classificação , DNA de Algas/análise , DNA de Protozoário/análise , DNA Ribossômico/análise , Dinoflagelados/citologia , Dinoflagelados/genética , Dinoflagelados/ultraestrutura , Microscopia Eletrônica de Varredura , República da Coreia , Análise de Sequência de DNA
9.
Harmful Algae ; 78: 1-8, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30196917

RESUMO

Three strains of the toxic benthic dinoflagellate Prorocentrum hoffmannianum were isolated in the Canary Islands (north-east Atlantic Ocean, Spain). The identity of the strains was determined by phylogenetic analyses of partial LSU rDNA (D1-D2 regions) but their morphology based on SEM images corresponded to P. maculosum. Their toxin profiles were analyzed by liquid chromatography and high resolution mass spectrometry analysis (LC-HRMS) on cell extracts and culture media. Okadaic acid and three analogs were detected in all strains. Rather, in culture media the detected compounds were variable among strains, two of them being okadaic acid analogs not found on cell extracts. As a result, the taxonomy of the species was revised and P. maculosum is proposed as a junior synonym of P. hoffmannianum whose description is emended.


Assuntos
Dinoflagelados/química , Dinoflagelados/classificação , Toxinas Marinhas/química , Ácido Okadáico/química , Cromatografia Líquida , Dinoflagelados/citologia , Dinoflagelados/genética , Espectrometria de Massas , Filogenia , RNA de Algas/análise , RNA de Protozoário/análise , RNA Ribossômico/análise , Espanha
10.
J Phycol ; 54(5): 744-761, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30144373

RESUMO

The genus Gymnodinium includes many morphologically similar species, but molecular phylogenies show that it is polyphyletic. Eight strains of Gymnodinium impudicum, Gymnodinium dorsalisulcum and a novel Gymnodinium-like species from Chinese and Malaysian waters and the Mediterranean Sea were established. All of these strains were examined with light microscopy, scanning electron microscopy and transmission electron microscopy. SSU, LSU and internal transcribed spacers rDNA sequences were obtained. A new genus, Wangodinium, was erected to incorporate strains with a loop-shaped apical structure complex (ASC) comprising two rows of amphiesmal vesicles, here referred to as a new type of ASC. The chloroplasts of Wangodinium sinense are enveloped by two membranes. Pigment analysis shows that peridinin is the main accessory pigment in W. sinense. Wangodinium differs from other genera mainly in its unique ASC, and additionally differs from Gymnodinium in the absence of nuclear chambers, and from Lepidodinium in the absence of Chl b and nuclear chambers. New morphological information was provided for G. dorsalisulcum and G. impudicum, e.g., a short sulcal intrusion in G. dorsalisulcum; nuclear chambers in G. impudicum and G. dorsalisulcum; and a chloroplast enveloped by two membranes in G. impudicum. Molecular phylogeny was inferred using maximum likelihood and Bayesian inference with independent SSU and LSU rDNA sequences. Our results support the classification of Wangodinium within the Gymnodiniales sensu stricto clade and it is close to Lepidodinium. Our results also support the close relationship among G. dorsalisulcum, G. impudicum, and Barrufeta. Further research is needed to assign these Gymnodinium species to Barrufeta or to erect new genera.


Assuntos
Dinoflagelados/citologia , Dinoflagelados/genética , Filogenia , China , Cloroplastos/ultraestrutura , DNA de Algas/análise , DNA de Protozoário/análise , DNA Ribossômico/análise , Dinoflagelados/classificação , Dinoflagelados/ultraestrutura , França , Malásia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão
11.
Harmful Algae ; 76: 58-65, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29887205

RESUMO

The occurrence of the ciguatera fish poisoning (CFP) causative Gambierdiscus spp. was confirmed in the Sea of Japan for the first time in 2009. This paper reports seasonal distribution of Gambierdiscus spp. and epiphytic diatoms in the Sea of Japan. Monitoring results suggested an antagonistic interaction in abundances between epiphytic diatoms and the dinoflagellate Gambierdiscus spp. Allelopathic effects of diatoms were considered to be involved in the competitive phenomenon. Therefore it is hypothesized that cell densities of epiphytic pennate diatoms on macroalgae are a novel determinant affecting the abundance of Gambierdiscus spp. other than sea water temperature, salinity and nutrients. Monitorings of the abundance of epiphytic diatoms would lead us to predict the occurrences of Gambierdiscus spp. blooms in the CFP area, and thereby the CFP risk assessments would be developed. Phylogenetic analyses indicated that Gambierdiscus spp. in the Sea of Japan belonged to Gambierdiscus sp. type 2 which was reported to be non-toxic. Nevertheless, based on morphological characteristics, at least two types of Gambierdiscus spp. were found in the Sea of Japan. It is needed to test the toxicity of the both types of Gambierdiscus recognized in the present study for evaluation of the probability of CFP outbreak risks in the Sea of Japan in the future.


Assuntos
Diatomáceas/fisiologia , Dinoflagelados/fisiologia , Monitoramento Ambiental , Proliferação Nociva de Algas , Alelopatia , Intoxicação por Ciguatera , DNA Ribossômico/análise , Dinoflagelados/classificação , Dinoflagelados/citologia , Japão , Oceanos e Mares , Filogenia , Dinâmica Populacional , Água do Mar , Alga Marinha/fisiologia
12.
Sci Rep ; 8(1): 9572, 2018 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-29934632

RESUMO

The formation, propagation, and maintenance of harmful algal blooms are of interest due to their negative effects on marine life and human health. Some bloom-forming algae utilize allelopathy, the release of compounds that inhibit competitors, to exclude other species dependent on a common pool of limiting resources. Allelopathy is hypothesized to affect bloom dynamics and is well established in the red tide dinoflagellate Karenia brevis. K. brevis typically suppresses competitor growth rather than being acutely toxic to other algae. When we investigated the effects of allelopathy on two competitors, Asterionellopsis glacialis and Thalassiosira pseudonana, using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS)-based metabolomics, we found that the lipidomes of both species were significantly altered. However, A. glacialis maintained a more robust metabolism in response to K. brevis allelopathy whereas T. pseudonana exhibited significant alterations in lipid synthesis, cell membrane integrity, and photosynthesis. Membrane-associated lipids were significantly suppressed for T. pseudonana exposed to allelopathy such that membranes of living cells became permeable. K. brevis allelopathy appears to target lipid biosynthesis affecting multiple physiological pathways suggesting that exuded compounds have the ability to significantly alter competitor physiology, giving K. brevis an edge over sensitive species.


Assuntos
Alelopatia , Membrana Celular/metabolismo , Dinoflagelados/citologia , Dinoflagelados/metabolismo , Metabolismo dos Lipídeos , Fotossíntese , Dinoflagelados/fisiologia , Fitoplâncton/fisiologia , Tilacoides/metabolismo
13.
Harmful Algae ; 74: 78-97, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29724345

RESUMO

Species of Fukuyoa, recently revised from the globular Gambierdiscus, are toxic benthic dinoflagellates associated with ciguatera. In this study, a total of ten strains of Fukuyoa collected from Hong Kong waters were characterized using morphological and phylogenetic analyses. Results from both analyses showed that one of the strains is a putative new species, namely Fukuyoa sp. HK Type 1 (plate formula Po, 3', 7″, 6c, 7s, 5‴, 1p and 2'‴ with a distinctive small and narrow cell shape, narrow Po plate, high Po pore density, large and broad Plate 1' but small and round Po pore size, small and narrow Plate 2', long and narrow Plates 2'‴ and 1p), and the others were F. ruetzleri. This is the first report of these two species of Fukuyoa in the South China Sea and Asia-Pacific region. Phylogenies on 18S, 28S D1/D3 and D8/D10 ribosomal DNA sequences strongly support that Fukuyoa sp. HK Type 1 is currently the most divergent species in the genus Fukuyoa. The diagrammatic plots on the p-distance matrices of 18S, 28S D1/D3 and D8/D10 and ITS regions resolved that the species of Fukuyoa were separated into three main groups, i.e., Fukuyoa sp. HK Type 1, F. paulensis and a group consisting of F. ruetzleri, F. yasumotoi and F. cf. yasumotoi, while Fukuyoa sp. HK Type 1 was always the most distant from the other two groups. Additionally, the pairwise p-distance values calculated based on the ITS region have always been the highest for pairs between Fukuyoa sp. HK Type 1 and other Fukuyoa species, ranging from 0.142 to 0.150. Our molecular results suggested that Fukuyoa sp. HK Type 1 is a putative new species. Both morphological and molecular data of more strains from different localities should be, however, collected to address its intraspecific variability and further evaluate its taxonomic status. A bioassay analysis demonstrated that algal lysates extracted from F. ruetzleri and Fukuyoa sp. HK Type 1 were lethal to brine shrimp larvae, indicating that both species were toxic. Bulk cultures were tested for Pacific ciguatoxins (P-CTXs) and maitotoxins (MTXs) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). All isolates of Fukuyoa produced neither P-CTXs nor MTX-1, but isolates of F. ruetzleri produced a compound putatively assigned as MTX-3. This study has updated the current biodiversity and distribution of the toxic benthic dinoflagellates Fukuyoa, and thus contributes to the understanding of their emerging threats to the sub-tropical reef systems locally and regionally.


Assuntos
Artemia/efeitos dos fármacos , Dinoflagelados/química , Dinoflagelados/classificação , Animais , Cromatografia Líquida , Recifes de Corais , DNA de Algas/análise , Dinoflagelados/citologia , Dinoflagelados/ultraestrutura , Hong Kong , Microscopia Eletrônica de Varredura , Oceanos e Mares , Filogenia , RNA Ribossômico 18S/análise , RNA Ribossômico 28S/análise , Espectrometria de Massas em Tandem , Testes de Toxicidade Aguda
14.
Sci Rep ; 8(1): 7011, 2018 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-29725114

RESUMO

The total dinoflagellate cyst community and the cysts of Cochlodinium polykrikoides in the surface sediments of South Sea (Tongyeong coast), South Korea, were analysed using next-generation sequencing (NGS) and morphological approaches. Dinoflagellate cysts can be highly abundant (111-4,087 cysts g-1 dry weight) and have diverse species composition. A total of 35 taxa of dinoflagellate cysts representing 16 genera, 21 species (including four unconfirmed species), and 14 complex species were identified by NGS analysis. Cysts of Scrippsiella spp (mostly Scrippsiella trochoidea) were the most dominant and Polykrikos schwartzii, Pentapharsodinium dalei, Ensiculifera carinata, and Alexandrium catenella/tamarense were common. Thus, a combination of NGS and morphological analysis is effective for studying the cyst communities present in a given environment. Although C. polykrikoides developed massive blooms during 2013-2014, microscopy revealed low density of their cysts, whereas no cysts were detected by NGS. However, the vegetative C. polykrikoides not appeared during 2015-2017 in spite of the observation of C. polykrikoides cysts. This suggests that the C. polykrikoides blooms were not due to development of their cysts but to other factors such as currents transporting them to a marine environment suitable for their growth.


Assuntos
Biodiversidade , Dinoflagelados/classificação , Dinoflagelados/isolamento & purificação , Sedimentos Geológicos/parasitologia , Animais , Dinoflagelados/citologia , Dinoflagelados/genética , Sequenciamento de Nucleotídeos em Larga Escala , República da Coreia
15.
Biochem Biophys Res Commun ; 499(4): 941-947, 2018 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-29626468

RESUMO

Oxygen supply is an important factor during Crypthecodinium cohnii fermentation for docosahexaenoic acid (DHA) production. However, few studies about the intrinsic correlation between dissolved oxygen (DO) and cellular metabolism have been reported. In this study, the responses of C. cohnii to different DO levels were evaluated. The results showed the growth and glucose consumption rates of C. cohnii were much higher under high oxygen supply condition. Furthermore, GC-MS based comparative metabolomic analysis was employed to discriminate the responsive metabolites associated with varying DO levels. The results showed the intermediates involved in glycolytic pathway and TCA cycle were up-regulated under high DO levels at exponential phase. At stationary phase, under high DO levels, metabolites involved in triacylglycerol metabolism were up-regulated, while the OPP pathway intermediate product ribose 5-phosphate was down-regulated. Together, these results provide useful insights into the functional metabolic relationship between DO levels and DHA production in C. cohnii.


Assuntos
Dinoflagelados/metabolismo , Ácidos Docosa-Hexaenoicos/metabolismo , Fermentação , Metabolômica/métodos , Oxigênio/metabolismo , Proliferação de Células , Dinoflagelados/citologia , Cromatografia Gasosa-Espectrometria de Massas , Glucose/metabolismo , Cinética , Análise de Componente Principal
16.
J Eukaryot Microbiol ; 65(6): 750-772, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29575394

RESUMO

A study of modern sediment from the Western Arctic has revealed the presence of a distinctive brown-colored cyst with a spherical central body bearing unbranched processes that are usually solid with a small basal pericoel. Distinctive barbs project from some processes, and process tips are usually minutely expanded into conjoined barbs. The archeopyle is apical and saphopylic. This cyst corresponds to Islandinium? cezare morphotype 2 of Head et al. (2001, J. Quat. Sci., 16:621). Phylogenetic analyses based on the small and large subunit rRNA genes infer close relationship with Islandinium minutum, the type of which is that of the genus. Re-examination of specimens of I. minutum reveals the presence of minute barbs on its processes, but differences with Islandinium? cezare morphotype 2 remain based on size, process distribution, and barb development. Furthermore, the internal transcribed spacer shows I. minutum to be distinct from this morphotype. On the basis of these small but discrete differences, we propose the new subspecies Islandinium minutum subsp. barbatum subsp. nov. Molecular sequencing of other cysts encountered, namely Echinidinium karaense, an unidentified flattened cyst, and "Polykrikos quadratus", places them in the Monovela clade, the latter showing greater morphological variability than previously thought.


Assuntos
DNA Ribossômico/genética , Dinoflagelados/classificação , Dinoflagelados/citologia , Dinoflagelados/genética , Filogenia , Esporos de Protozoários/citologia , Regiões Árticas , DNA de Protozoário/genética , Dinoflagelados/isolamento & purificação , Sedimentos Geológicos/parasitologia , Microscopia Eletrônica de Varredura , RNA Ribossômico 18S/genética , Água do Mar/parasitologia , Análise de Sequência de DNA
17.
J Eukaryot Microbiol ; 65(5): 612-626, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29397033

RESUMO

The mixotroph Yihiella yeosuensis is a small- and fast-swimming dinoflagellate. To investigate its protistan predators, interactions between Y. yeosuensis and 11 heterotrophic protists were explored. No potential predators were able to feed on actively swimming Y. yeosuensis cells, which escaped via rapid jumps, whereas Aduncodinium glandula, Oxyrrhis marina, and Strombidinopsis sp. (approximately 150 µm in cell length) were able to feed on weakly swimming cells that could not jump. Furthermore, Gyrodinium dominans, Luciella masanensis, and Pfiesteria piscicida were able to feed on heat-killed Yihiella cells, whereas Gyrodinium moestrupii, Noctiluca scintillans, Oblea rotunda, Polykrikos kofoidii, and Strombidium sp. (20 µm) did not feed on them. Thus, the jumping behavior of Y. yeosuensis might be primarily responsible for the observed lack of predation. With increasing Yihiella concentration, the growth rate of O. marina decreased, whereas that of Strombidinopsis did not change. However, with increasing Yihiella concentration (up to 530 ng C/ml), the ingestion rate of Strombidinopsis on Yihiella increased linearly. The highest ingestion rate was 24.1 ng C per predator per d. The low daily carbon acquisition from Yihiella relative to the body carbon content of Strombidinopsis might be responsible for its negligible growth. Thus, Y. yeosuensis might have an advantage over its competitors due to its low mortality rate.


Assuntos
Dinoflagelados/fisiologia , Comunicação Celular , Dinoflagelados/classificação , Dinoflagelados/citologia , Ingestão de Alimentos , Processos Heterotróficos
18.
J Phycol ; 54(1): 126-137, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29194622

RESUMO

The family Ceratocoryaceae includes the genera Ceratocorys, Protoceratium, and Schuettiella, whose phylogenetic relationships are poorly known. Here, the new non-yessotoxin-producing species of the genus Ceratocorys, Ceratocorys mariaovidiorum sp. nov., previously reported as the toxic Protoceratium reticulatum, is described from examinations by light and scanning electron microscopy, molecular phylogeny, and toxin analyses. The species description is made from culture samples of strains CCMP1740 and CCMP404 from USA waters. Ceratocorys mariaovidiorum is globular and has thick and strongly reticulated plates with one pore within each reticule, just like P. reticulatum, but the key difference between the two species is the presence of five precingular plates in C. mariaovidiorum instead of six as in P. reticulatum. The thecal plate formula is Po, 4', 0a, 5″, 6c, ~7s, 5‴, 0p, 2''''. The apical pore plate is oval with a λ-shaped pore. The first apical plate is narrow with a ventral pore on the right anterior side; it contacts the apical pore plate and its contact with the anterior sulcal plate is slight or absent. The fourth precingular plate of other Gonyaulacales is absent. Ceratocorys mariaovidiorum may have small spines on the second antapical plate. A phylogenetic study based on internal transcribed spacer/5.8SrDNA supports the morphological classification of C. mariaovidiorum as a new species of Ceratocorys and in a different clade from P. reticulatum.


Assuntos
Dinoflagelados/classificação , Dinoflagelados/genética , DNA Espaçador Ribossômico/análise , Dinoflagelados/citologia , Dinoflagelados/ultraestrutura , Microscopia Eletrônica de Varredura , Filogenia , RNA de Algas/análise , RNA de Protozoário/análise , RNA Ribossômico 5,8S/análise , Estados Unidos
19.
J Phycol ; 54(1): 138-149, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29194636

RESUMO

A planktonic-benthic relationship has been described for many dinoflagellate species as part of their ecological strategy to overcome highly variable aquatic environments. Here, the phylogenetically and morphologically related marine dinoflagellates Protoceratium reticulatum and Ceratocorys mariaovidiorum were studied in relation to an unknown benthic life form. In vivo and fixed samples from cultures were analyzed in detail by light and scanning electron microscopy. In both species, a cell type with a morphology different from that of vegetative cells was observed in cultures grown until stationary phase. This cell type was always benthic, swimming sporadically only when it was disturbed. Its main feature included a strong dorsoventral compression. These cells originated from vegetative cells whose protoplasm underwent a progressive flattening, resulting in a gradual detachment of the reticulate and thick thecal plates and the formation of very thin non-reticulated new plates with pores. When returned to fresh full-strength medium, the cells recovered their spherical vegetative-like morphology, including new reticulated thick plates and subsequent cell divisions. The kinetics of flattened cell formation showed that in both species, this cell type increased exponentially until the onset of the culture stationary phase and then decreased. The results of this study are discussed in the context of the planktonic-benthic coupling in dinoflagellate life cycles, including those newly appreciated to be well adapted to the benthic environment.


Assuntos
Dinoflagelados/crescimento & desenvolvimento , Estágios do Ciclo de Vida , Chile , Dinoflagelados/citologia , Dinoflagelados/ultraestrutura , Traços de História de Vida , Microscopia Eletrônica de Varredura , Espanha
20.
Cytoskeleton (Hoboken) ; 75(1): 12-21, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28771965

RESUMO

The cytoskeleton is crucial to cell mechanics and sensing the extracellular physical environment. The objective of this study was to examine the role of the cortical cytoskeleton in mechanosensitivity in a unicellular protist, the marine dinoflagellate Lingulodinium polyedra, using its intrinsic bioluminescence as a rapid reporter of mechanotransduction. Pharmacological treatments resolved effects due to immediate cytoskeleton disruption from those due to cytoskeletal remodeling during the light to dark phase transition. The cytoskeleton was visualized by confocal laser scanning microscopy of immunohistochemically labeled microtubules and phalloidin labeled F-actin, and mechanosensitivity assessed based on the bioluminescence response to mechanical stimulation measured during the dark phase. Latrunculin B treatment after the transition from the light to dark phase resulted in some disruption of cortical F-actin, no observed effect on the cortical microtubules, and partial inhibition of the bioluminescence response. Treatment with oryzalin, which depolarizes microtubules, completely disrupted the microtubule network and cortical F-actin, and partially inhibited bioluminescence. These results demonstrate that cells retain some mechanosensitivity despite a disrupted cytoskeleton; link mechanosensitivity to intact F-actin; show a close connection between F-actin and microtubules comprising the cortical cytoskeleton; confirm a strong contribution of the actin cytoskeleton to the translocation of scintillons, vesicles containing the luminescent chemistry; and support the role of the actin cytoskeleton in the association of scintillons with the vacuole membrane.


Assuntos
Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Dinoflagelados/metabolismo , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Dinoflagelados/citologia , Imuno-Histoquímica , Medições Luminescentes , Tiazolidinas/farmacologia
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