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Marine Drugs Oct 2019Marine polyether toxins, mainly produced by marine dinoflagellates, are novel, complex, and diverse natural products with extensive toxicological and pharmacological... (Review)
Review
Marine polyether toxins, mainly produced by marine dinoflagellates, are novel, complex, and diverse natural products with extensive toxicological and pharmacological effects. Owing to their harmful effects during outbreaks of marine red tides, as well as their potential value for the development of new drugs, marine polyether toxins have been extensively studied, in terms of toxicology, pharmacology, detection, and analysis, structural identification, as well as their biosynthetic mechanisms. Although the biosynthetic mechanisms of marine polyether toxins are still unclear, certain progress has been made. In this review, research progress and current knowledge on the biosynthetic mechanisms of polyether toxins are summarized, including the mechanisms of carbon skeleton deletion, pendant alkylation, and polyether ring formation, along with providing a summary of mined biosynthesis-related genes. Finally, future research directions and applications of marine polyether toxins are discussed.
Topics: Alkylation; Anti-Bacterial Agents; Aquatic Organisms; Biosynthetic Pathways; Computational Biology; Dinoflagellida; Ethers; Marine Toxins
PubMed: 31652489
DOI: 10.3390/md17100594 -
Current Biology : CB Jun 2022Photosynthesis shapes the symbiotic relationships between cnidarians and Symbiodiniaceae algae-with many cnidarian hosts requiring symbiont photosynthate for...
Photosynthesis shapes the symbiotic relationships between cnidarians and Symbiodiniaceae algae-with many cnidarian hosts requiring symbiont photosynthate for survival-but little is known about how photosynthesis impacts symbiosis establishment. Here, we show that during symbiosis establishment, infection, proliferation, and maintenance can proceed without photosynthesis, but the ability to do so is dependent on specific cnidarian-Symbiodiniaceae relationships. The evaluation of 31 pairs of symbiotic relationships (five species of Symbiodiniaceae in sea anemone, coral, and jellyfish hosts) revealed that infection can occur without photosynthesis. A UV mutagenesis method for Symbiodiniaceae was established and used to generate six photosynthetic mutants that can infect these hosts. Without photosynthesis, Symbiodiniaceae cannot proliferate in the sea anemone Aiptasia or jellyfish Cassiopea but can proliferate in the juvenile polyps of the coral Acropora. After 6 months of darkness, Breviolum minutum is maintained within Aiptasia, indicating that Symbiodiniaceae maintenance can be independent of photosynthesis. Manipulating photosynthesis provides insights into cnidarian-Symbiodiniaceae symbiosis.
Topics: Animals; Anthozoa; Dinoflagellida; Photosynthesis; Sea Anemones; Symbiosis
PubMed: 35504283
DOI: 10.1016/j.cub.2022.04.021 -
ELife Jul 2019Coral reefs are some of the most important and ecologically diverse marine environments. At the base of the reef ecosystem are dinoflagellate algae, which live...
Coral reefs are some of the most important and ecologically diverse marine environments. At the base of the reef ecosystem are dinoflagellate algae, which live symbiotically within coral cells. Efforts to understand the relationship between alga and coral have been greatly hampered by the lack of an appropriate dinoflagellate genetic transformation technology. By making use of the plasmid-like fragmented chloroplast genome, we have introduced novel genetic material into the dinoflagellate chloroplast genome. We have shown that the introduced genes are expressed and confer the expected phenotypes. Genetically modified cultures have been grown for 1 year with subculturing, maintaining the introduced genes and phenotypes. This indicates that cells continue to divide after transformation and that the transformation is stable. This is the first report of stable chloroplast transformation in dinoflagellate algae.
Topics: Chloroplasts; Dinoflagellida; Gene Expression; Genetics, Microbial; Genomic Instability; Phenotype; Transformation, Genetic
PubMed: 31317866
DOI: 10.7554/eLife.45292 -
International Journal of Molecular... Oct 2022Dinoflagellates bioluminescence mechanism depends upon a luciferin-luciferase reaction that promotes blue light emission (480 nm) in specialized luminogenic organelles... (Review)
Review
Dinoflagellates bioluminescence mechanism depends upon a luciferin-luciferase reaction that promotes blue light emission (480 nm) in specialized luminogenic organelles called scintillons. The scintillons contain luciferin, luciferase and, in some cases, a luciferin-binding protein (LBP), which prevents luciferin from non-enzymatic oxidation in vivo. Even though dinoflagellate bioluminescence has been studied since the 1950s, there is still a lack of mechanistic understanding on whether the light emission process involves a peroxidic intermediate or not. Still, bioassays employing luminous dinoflagellates, usually from or genus, can be used to assess the toxicity of metals or organic compounds. In these dinoflagellates, the response to toxicity is observed as a change in luminescence, which is linked to cellular respiration. As a result, these changes can be used to calculate a percentage of light inhibition that correlates directly with toxicity. This current approach, which lies in between fast bacterial assays and more complex toxicity tests involving vertebrates and invertebrates, can provide a valuable tool for detecting certain pollutants, e.g., metals, in marine sediment and seawater. Thus, the present review focuses on how the dinoflagellates bioluminescence can be applied to evaluate the risks caused by contaminants in the marine environment.
Topics: Animals; Dinoflagellida; Luciferases; Luminescence; Biological Assay; Geologic Sediments; Luminescent Measurements
PubMed: 36361798
DOI: 10.3390/ijms232113012 -
Applied and Environmental Microbiology Aug 2019Given the ecological significance of microorganisms in algal blooming events, it is critical to understand the mechanisms regarding their distribution under different...
Given the ecological significance of microorganisms in algal blooming events, it is critical to understand the mechanisms regarding their distribution under different conditions. We tested the hypothesis that microbial community succession is strongly associated with algal bloom stages, and that the assembly mechanisms are cocontrolled by deterministic and stochastic processes. Community structures and underlying ecological processes of microbial populations (attached and free-living bacteria) at three algal bloom stages (pre-, during, and postbloom) over a complete dinoflagellate bloom were investigated. Both attached and free-living taxa had a strong response to the bloom event, and the latter was more sensitive than the former. The contribution of environmental parameters to microbial variability was 40.2%. Interaction analysis showed that complex positive or negative correlation networks exist in phycosphere microbes. These relationships were the potential drivers of mutualist and competitive interactions that impacted bacterial succession. Null model analysis showed that the attached bacterial community primarily exhibited deterministic processes at pre- and during-bloom stages, while dispersal-related processes contributed to a greater extent at the postbloom stage. In the free-living bacterial community, homogeneous selection and dispersal limitation dominated in the initial phase, which gave way to more deterministic processes at the two later stages. Relative contribution analyses further demonstrated that the community turnover of attached bacteria was mainly driven by environmental selection, while stochastic factors had partial effects on the assembly of free-living bacteria. Taken together, these data demonstrated that a robust link exists between bacterioplankton community structure and bloom progression, and phycosphere microbial succession trajectories are cogoverned by both deterministic and random processes. Disentangling the mechanisms shaping bacterioplankton communities during a marine ecological event is a core concern for ecologists. Harmful algal bloom (HAB) is a typical ecological disaster, and its formation is significantly influenced by alga-bacterium interactions. Microbial community shifts during the HAB process are relatively well known. However, the assembly processes of microbial communities in an HAB are not fully understood, especially the relative influences of deterministic and stochastic processes. We therefore analyzed the relative contributions of deterministic and stochastic processes during an HAB event. Both free-living and attached bacterial groups had a dramatic response to the HAB, and the relative importance of determinism versus stochasticity varied between the two bacterial groups at various bloom stages. Environmental factors and biotic interactions were the main drivers impacting the microbial shift process. Our results strengthen the understanding of the ecological mechanisms controlling microbial community patterns during the HAB process.
Topics: Aquatic Organisms; Dinoflagellida; Harmful Algal Bloom; Microbiota
PubMed: 31126952
DOI: 10.1128/AEM.00349-19 -
Toxicon : Official Journal of the... May 2022Ciguatoxins (CTXs) and gambierones are ladder-shaped polyethers associated with ciguatera poisoning and Gambierdiscus spp. Several of these compounds contain carbonyl or...
Ciguatoxins (CTXs) and gambierones are ladder-shaped polyethers associated with ciguatera poisoning and Gambierdiscus spp. Several of these compounds contain carbonyl or hemiketal groups, which have the potential to exchange with O-labeled water under acidic conditions. The effects of solvent composition and acid on the rate of exchange and on the stability of the labels at various pH values were assessed to optimize the incorporation of O into Caribbean ciguatoxin-1 and -2 (C-CTX1/2), gambierone, and 44-methylgambierone. LC-HRMS results showed that O-labeling occurred at the hydroxy group of the hemiketal at C-56 in C-CTX1/2, and at the hydroxy group of the hemiketal at C-4 and the ketone at C-40 in gambierones. Labeling occurred very rapidly (complete in <30 min) for C-CTX1/2, and more slowly (complete in ca. 16 h) for both gambierones. Labeled C-CTX1/2 was reduced with sodium borohydride to produce O-labeled C-CTX3/4. The incorporated O labels in the gambierones and C-CTXs were retained in aqueous solvent mixtures under neutral conditions in a short-term stability study, demonstrating that these O-labeled toxins have the potential to be used in isotope dilution and metabolism studies.
Topics: Caribbean Region; Ciguatera Poisoning; Ciguatoxins; Dinoflagellida; Ethers; Humans; Oxygen Isotopes
PubMed: 35300989
DOI: 10.1016/j.toxicon.2022.03.005 -
Molecules (Basel, Switzerland) Jul 2023Amphidinolides are a family of more than forty macrolides of varying sizes and complex structures isolated from dinoflagellates of the genus . Although all of them... (Review)
Review
Amphidinolides are a family of more than forty macrolides of varying sizes and complex structures isolated from dinoflagellates of the genus . Although all of them display potent-to-moderate cytotoxicity, their full bioactivity profile and mode of action have not been fully investigated. Access to enough material is needed for these studies, but samples of these compounds are limited due to the minute amounts that can only be obtained by either large-scale cultivation of the organism that produces them or by total synthesis. Of all the amphidinolides known to date, only the targets of five of them (B1, H1, J, K, and X) have been examined and all have been found to interact with actin, a crucial cytoskeletal protein. This paper reviews what is currently known about actin-interacting amphidinolides, with a focus on the research of our group. Amphidinolides J and X are F-actin destabilizers, whereas Amphidinolides H1 and K stabilize actin filaments, likely via different mechanisms. More precise details of the interaction between amphidinolides and actin are missing.
Topics: Actins; Molecular Structure; Macrolides; Dinoflagellida
PubMed: 37446910
DOI: 10.3390/molecules28135249 -
Scientific Reports Feb 2023It is important to decipher the diversity and distribution of benthic dinoflagellates, as there are many morphologically indistinct taxa that differ from one another in...
It is important to decipher the diversity and distribution of benthic dinoflagellates, as there are many morphologically indistinct taxa that differ from one another in production of potent toxins. To date, the genus Ostreopsis comprises twelve described species, of which seven are potentially toxic and produce compounds presenting a threat to human and environmental health. In this study, isolates previously identified as "Ostreopsis sp. 3" were sampled from the area where it was first reported, Rarotonga, Cook Islands, and have been taxonomically and phylogenetically characterised as Ostreopsis tairoto sp. nov. Phylogenetically, the species is closely related to "Ostreopsis sp. 8", O. mascarenensis, "O. sp. 4", O. fattorussoi, O. rhodesiae and O. cf. siamensis. Previously, it was considered a part of the O. cf. ovata complex but can be distinguished from O. cf. ovata based on the small pores identified on this study, and from O. fattorussoi and O. rhodesiae based on relative lengths of the 2' plates. No known palytoxin -like compounds were detected in strains investigated in this study. Strains of O. lenticularis, Coolia malayensis and C. tropicalis were also identified and described. This study advances our knowledge of biogeography, distribution, and toxins of Ostreopsis and Coolia species.
Topics: Humans; Pacific Ocean; Dinoflagellida; Polynesia; Antarctic Regions
PubMed: 36813881
DOI: 10.1038/s41598-023-29969-z -
PloS One 2022Nearly all annual blooms of the toxic dinoflagellate Karenia brevis (K. brevis) pose a serious threat to coastal Southwest Florida. These blooms discolor water, kill...
Nearly all annual blooms of the toxic dinoflagellate Karenia brevis (K. brevis) pose a serious threat to coastal Southwest Florida. These blooms discolor water, kill fish and marine mammals, contaminate shellfish, cause mild to severe respiratory irritation, and discourage tourism and recreational activities, leading to significant health and economic impacts in affected communities. Despite these issues, we still lack standard measures suitable for assessing bloom severity or for evaluating the efficacy of modeling efforts simulating bloom initiation and intensity. In this study, historical cell count observations along the southwest Florida shoreline from 1953 to 2019 were used to develop monthly and annual bloom severity indices (BSI). Similarly, respiratory irritation observations routinely reported in Sarasota and Manatee Counties from 2006 to 2019 were used to construct a respiratory irritation index (RI). Both BSI and RI consider spatial extent and temporal evolution of the bloom, and can be updated routinely and used as objective criteria to aid future socioeconomic and scientific studies of K. brevis. These indices can also be used to help managers and decision makers both evaluate the risks along the coast during events and design systems to better respond to and mitigate bloom impacts. Before 1995, sampling was done largely in response to reports of discolored water, fish kills, or respiratory irritation. During this timeframe, lack of sampling during the fall, when blooms typically occur, generally coincided with periods of more frequent-than-usual offshore winds. Consequently, some blooms may have been undetected or under-sampled. As a result, the BSIs before 1995 were likely underestimated and cannot be viewed as accurately as those after 1995. Anomalies in the frequency of onshore wind can also largely account for the discrepancies between BSI and RI during the period from 2006 to 2019. These findings highlighted the importance of onshore wind anomalies when predicting respiratory irritation impacts along beaches.
Topics: Dinoflagellida; Florida; Forecasting; Harmful Algal Bloom; Humans; Marine Toxins; Respiratory System; Respiratory Tract Infections
PubMed: 34986155
DOI: 10.1371/journal.pone.0260755 -
Marine Drugs Jan 2023Dinoflagellates are a major aquatic protist group with amphiesma, multiple cortical membranous "cell wall" layers that contain large circum-cortical alveolar sacs (AVs).... (Review)
Review
Dinoflagellates are a major aquatic protist group with amphiesma, multiple cortical membranous "cell wall" layers that contain large circum-cortical alveolar sacs (AVs). AVs undergo extensive remodeling during cell- and life-cycle transitions, including ecdysal cysts (ECs) and resting cysts that are important in some harmful algal bloom initiation-termination. AVs are large cortical vesicular compartments, within which are elaborate cellulosic thecal plates (CTPs), in thecate species, and the pellicular layer (PL). AV-CTPs provide cellular mechanical protection and are targets of vesicular transport that are replaced during EC-swarmer cell transition, or with increased deposition during the cellular growth cycle. AV-PL exhibits dynamical-replacement with vesicular trafficking that are orchestrated with amphiesmal chlortetracycline-labeled Ca stores signaling, integrating cellular growth with different modes of cell division cycle/progression. We reviewed the dynamics of amphiesma during different cell division cycle modes and life cycle stages, and its multifaceted regulations, focusing on the regulatory and functional readouts, including the coral-zooxanthellae interactions.
Topics: Animals; Dinoflagellida; Molting; Harmful Algal Bloom; Cell Wall; Cell Cycle; Life Cycle Stages
PubMed: 36827111
DOI: 10.3390/md21020070