-
Marine Drugs Mar 2024This study reports the first detection of the marine neurotoxin pinnatoxin-G (PnTX-G) in clams collected in the northwestern Adriatic Sea (Italy). It also represents the...
This study reports the first detection of the marine neurotoxin pinnatoxin-G (PnTX-G) in clams collected in the northwestern Adriatic Sea (Italy). It also represents the first report of the potential toxin-producing dinoflagellate, , in Italian seas. This result, from the coasts of the Emilia-Romagna Region, indicates a successful colonization process, reflecting conditions in France where was initially documented. In this case, the concentration of PnTXs was very low, making further sampling necessary to fully understand the extent of the phenomenon. Discussions on the need to obtain more data to support a proper risk assessment and the need to implement a monitoring program that includes emerging marine biotoxins are also included.
Topics: Humans; Alkaloids; Dinoflagellida; France; Italy; Spiro Compounds
PubMed: 38535463
DOI: 10.3390/md22030122 -
Marine Drugs Mar 2024The genus produces an array of bioactive hydrophilic and lipophilic secondary metabolites that range in mode of action and toxicity. In this study, the metabolite...
The genus produces an array of bioactive hydrophilic and lipophilic secondary metabolites that range in mode of action and toxicity. In this study, the metabolite fingerprint was mapped for thirteen , five and two species (34 isolates) by assessing the production of 56 characterised secondary metabolites. was the only species to produce Pacific-ciguatoxin-3B (P-CTX3B), P-CTX3C, iso-P-CTX3B/C, P-CTX4A, P-CTX4B and iso-P-CTX4A/B. produced maitotoxin-1 (MTX-1) and MTX-5, produced MTX-6 and produced MTX-7. Ubiquitous production of 44-methylgambierone was observed amongst all the isolates, with nine species also producing gambierone. Additional gambierone analogues, including anhydrogambierone (tentatively described herein), were also detected in all species, two and two species. Gambieroxide was detected in and and gambieric acid A was detected in ten species, with (CAWD381) being the only isolate to produce gambieric acids A-D. This study has demonstrated that the isolates tested to date produce the known CTXs or MTXs, but not both, and highlighted several species that produced 'unknown' compounds displaying characteristics of cyclic polyethers, which will be the focus of future compound discovery efforts.
Topics: Dinoflagellida; Ciguatoxins; Ethers; Serogroup
PubMed: 38535460
DOI: 10.3390/md22030119 -
BMC Ecology and Evolution Mar 2024Dinoflagellates play critical roles in the functioning of marine ecosystems but also may pose a hazard to human and ecosystem health by causing harmful algal blooms...
BACKGROUND
Dinoflagellates play critical roles in the functioning of marine ecosystems but also may pose a hazard to human and ecosystem health by causing harmful algal blooms (HABs). The Coral Sea is a biodiversity hotspot, but its dinoflagellate assemblages in pelagic waters have not been studied by modern sequencing methods. We used metabarcoding of the 18 S rRNA V4 amplicon to assess the diversity and structure of dinoflagellate assemblages throughout the water column to a depth of 150 m at three stations in the Western Coral Sea. Additionally, at one station we compared metabarcoding with morphological methods to optimise identification and detection of dinoflagellates.
RESULTS
Stratification of dinoflagellate assemblages was evident in depth-specific relative abundances of taxonomic groups; the greatest difference was between the 5-30 m assemblages and the 130-150 m assemblages. The relative abundance of Dinophyceae (photosynthetic and heterotrophic) decreased with increasing depth, whereas that of Syndiniales (parasitic) increased with increasing depth. The composition of major taxonomic groups was similar among stations. Taxonomic richness and diversity of amplicon sequence variants (ASVs) were similar among depths and stations; however, the abundance of dominant taxa was highest within 0-30 m, and the abundance of rare taxa was highest within 130-150 m, indicating adaptations to specific depth strata. The number of unclassified ASVs at the family and species levels was very high, particularly for Syndinian representatives.
CONCLUSIONS
Dinoflagellate assemblages in open water of the Coral Sea are highly diverse and taxonomically stratified by depth; patterns of relative abundance along the depth gradient reflect environmental factors and ecological processes. Metabarcoding detects more species richness than does traditional microscopical methods of sample analysis, yet the methods are complementary, with morphological analysis revealing additional richness. The large number of unclassified dinoflagellate-ASVs indicates a need for improved taxonomic reference databases and suggests presence of dinoflagellate-crypto and-morphospecies.
Topics: Animals; Humans; Anthozoa; Ecosystem; Biodiversity; Water; Dinoflagellida
PubMed: 38528460
DOI: 10.1186/s12862-024-02220-7 -
Scientific Reports Mar 2024During evolution of Dinophyceae, size reduction of the episome has occurred in several lineages (including unarmoured Amphidiniales and armoured Prorocentrales). One...
Oxytoxaceae are prorocentralean rather than peridinialean dinophytes and taxonomic clarification of heterotrophic Oxytoxum lohmannii (≡ "Amphidinium" crassum) by epitypification.
During evolution of Dinophyceae, size reduction of the episome has occurred in several lineages (including unarmoured Amphidiniales and armoured Prorocentrales). One such species is Amphidinium crassum, whose taxonomic identity is elusive though showing morphological similarities with Oxytoxaceae (currently placed in armoured Peridiniales). Plankton samples were taken at the type locality of A. crassum in Kiel Bight (Baltic Sea) in order to establish monoclonal strains. The protist material was examined in detail using light and electron microscopy, and a long (2984 bp) ribosomal RNA sequence gained was part of a taxon sample comprising 206 specimen vouchers and representing the known molecular diversity of Dinophyceae. Cells of A. crassum were ovoid and exhibited a plate pattern po, 4', 1a, 6'', 5c, 4s, 5''', 1''''. In the molecular phylogeny, the species seemed to belong neither to Amphidiniales nor to Peridiniales but to Prorocentrales and clustered with other representatives of Oxytoxaceae. The morphological diversity of Prorocentrales appears thus expanded, and the group may include a number of previously unrecognised representatives unusually having five postcingular and only a single antapical plate. The taxonomic identity of A. crassum is clarified by epitypification, and the species notably exhibits both an apical pore and an additional epithecal pore.
Topics: Dinoflagellida; RNA, Ribosomal; Phylogeny
PubMed: 38509105
DOI: 10.1038/s41598-024-56848-y -
EMBO Reports Apr 2024Dinoflagellates are a diverse group of ecologically significant micro-eukaryotes that can serve as a model system for plastid symbiogenesis due to their susceptibility...
Dinoflagellates are a diverse group of ecologically significant micro-eukaryotes that can serve as a model system for plastid symbiogenesis due to their susceptibility to plastid loss and replacement via serial endosymbiosis. Kareniaceae harbor fucoxanthin-pigmented plastids instead of the ancestral peridinin-pigmented ones and support them with a diverse range of nucleus-encoded plastid-targeted proteins originating from the haptophyte endosymbiont, dinoflagellate host, and/or lateral gene transfers (LGT). Here, we present predicted plastid proteomes from seven distantly related kareniaceans in three genera (Karenia, Karlodinium, and Takayama) and analyze their evolutionary patterns using automated tree building and sorting. We project a relatively limited ( ~ 10%) haptophyte signal pointing towards a shared origin in the family Chrysochromulinaceae. Our data establish significant variations in the functional distributions of these signals, emphasizing the importance of micro-evolutionary processes in shaping the chimeric proteomes. Analysis of plastid genome sequences recontextualizes these results by a striking finding the extant kareniacean plastids are in fact not all of the same origin, as two of the studied species (Karlodinium armiger, Takayama helix) possess plastids from different haptophyte orders than the rest.
Topics: Dinoflagellida; Symbiosis; Phylogeny; Proteome; Plastids
PubMed: 38499810
DOI: 10.1038/s44319-024-00103-y -
Scientific Reports Mar 2024Two gene regions commonly used to characterise the diversity of eukaryotic communities using metabarcoding are the 18S ribosomal DNA V4 and V9 gene regions. We assessed...
Two gene regions commonly used to characterise the diversity of eukaryotic communities using metabarcoding are the 18S ribosomal DNA V4 and V9 gene regions. We assessed the effectiveness of these two regions for characterising diverisity of coastal eukaryotic microalgae communities (EMCs) from tropical and temperate sites. We binned amplicon sequence variants (ASVs) into the high level taxonomic groups: dinoflagellates, pennate diatoms, radial centric diatoms, polar centric diatoms, chlorophytes, haptophytes and 'other microalgae'. When V4 and V9 generated ASV abundances were compared, the V9 region generated a higher number of raw reads, captured more diversity from all high level taxonomic groups and was more closely aligned with the community composition determined using light microscopy. The V4 region did resolve more ASVs to a deeper taxonomic resolution within the dinoflagellates, but did not effectively resolve other major taxonomic divisions. When characterising these communities via metabarcoding, the use of multiple gene regions is recommended, but the V9 gene region can be used in isolation to provide high-level community biodiversity to reflect relative abundances within groups. This approach reduces the cost of sequencing multiple gene regions whilst still providing important baseline ecosystem function information.
Topics: Ecosystem; Microalgae; Biodiversity; Diatoms; DNA, Ribosomal; Dinoflagellida; RNA, Ribosomal, 18S; Phylogeny
PubMed: 38499675
DOI: 10.1038/s41598-024-56993-4 -
Response of the toxic dinoflagellate Alexandrium minutum to exudates of the eelgrass Zostera marina.Harmful Algae Mar 2024Biotic interactions are a key factor in the development of harmful algal blooms. Recently, a lower abundance of planktonic dinoflagellates has been reported in areas...
Biotic interactions are a key factor in the development of harmful algal blooms. Recently, a lower abundance of planktonic dinoflagellates has been reported in areas dominated by seagrass beds, suggesting a negative interaction between both groups of organisms. The interaction between planktonic dinoflagellates and marine phanerogams, as well as the way in which bacteria can affect this interaction, was studied in two experiments using a non-axenic culture of the toxic dinoflagellate Alexandrium minutum exposed to increasing additions of eelgrass (Zostera marina) exudates from old and young leaves and to the presence or absence of antibiotics. In these experiments, A. minutum abundance, growth rate and photosynthetic efficiency (Fv/Fm), as well as bacterial abundance, were measured every 48 h. Toxin concentration per cell was determined at the end of both experiments. Our results demonstrated that Z. marina exudates reduced A. minutum growth rate and, in one of the experiments, also the photosynthetic efficiency. These results are not an indirect effect mediated by the bacteria in the culture, although their growth modify the magnitude of the negative impact on the dinoflagellate growth rate. No clear pattern was observed in the variation of toxin production with the treatments.
Topics: Zosteraceae; Dinoflagellida; Harmful Algal Bloom; Photosynthesis; Marine Toxins; Plankton; Bacteria
PubMed: 38485446
DOI: 10.1016/j.hal.2024.102605 -
STAR Protocols Jun 2024Dinoflagellate genomes often are very large and difficult to assemble, which has until recently precluded their analysis with modern functional genomic tools. Here, we...
Dinoflagellate genomes often are very large and difficult to assemble, which has until recently precluded their analysis with modern functional genomic tools. Here, we present a protocol for mapping three-dimensional (3D) genome organization in dinoflagellates and using it for scaffolding their genome assemblies. We describe steps for crosslinking, nuclear lysis, denaturation, restriction digest, ligation, and DNA shearing and purification. We then detail procedures sequencing library generation and computational analysis, including initial Hi-C read mapping and 3D-DNA scaffolding/assembly correction. For complete details on the use and execution of this protocol, please refer to Marinov et al..
Topics: Dinoflagellida; Genome, Protozoan; Genomics; Chromosome Mapping; Sequence Analysis, DNA
PubMed: 38483898
DOI: 10.1016/j.xpro.2024.102941 -
Applied and Environmental Microbiology Apr 2024The thermal bleaching percentage of coral holobionts shows interspecific differences under heat-stress conditions, which are closely related to the coral-associated...
The thermal bleaching percentage of coral holobionts shows interspecific differences under heat-stress conditions, which are closely related to the coral-associated microbiome. However, the ecological effects of community dynamics and interactions between Symbiodiniaceae and fungi on coral thermal bleaching susceptibility remain unclear. In this study, we analyzed the diversity, community structure, functions, and potential interaction of Symbiodiniaceae and fungi among 18 coral species from a high thermal bleaching risk atoll using next-generation sequencing. The results showed that heat-tolerant C3u sub-clade and dominated the Symbiodiniaceae community of corals and that there were no core amplicon sequence variants in the coral-associated fungal community. Fungal richness and the abundance of confirmed functional animal-plant pathogens were significantly positively correlated with the coral thermal bleaching percentage. Fungal indicators, including Didymellaceae, Chaetomiaceae, , and , were identified in corals. Each coral species had a complex Symbiodiniaceae-fungi interaction network (SFIN), which was driven by the dominant Symbiodiniaceae sub-clades. The SFINs of coral holobionts with low thermal bleaching susceptibility exhibited low complexity and high betweenness centrality. These results indicate that the extra heat tolerance of coral in Huangyan Island may be linked to the high abundance of heat-tolerant Symbiodiniaceae. Fungal communities have high interspecific flexibility, and the increase of fungal diversity and pathogen abundance was correlated with higher thermal bleaching susceptibility of corals. Moreover, fungal indicators were associated with the degrees of coral thermal bleaching susceptibility, including both high and intermediate levels. The topological properties of SFINs suggest that heat-tolerant coral have limited fungal parasitism and strong microbial network resilience.IMPORTANCEGlobal warming and enhanced marine heatwaves have led to a rapid decline in coral reef ecosystems worldwide. Several studies have focused on the impact of coral-associated microbiomes on thermal bleaching susceptibility in corals; however, the ecological functions and interactions between Symbiodiniaceae and fungi remain unclear. We investigated the microbiome dynamics and potential interactions of Symbiodiniaceae and fungi among 18 coral species in Huangyan Island. Our study found that the Symbiodiniaceae community of corals was mainly composed of heat-tolerant C3u sub-clade and . The increase in fungal diversity and pathogen abundance has close associations with higher coral thermal bleaching susceptibility. We first constructed an interaction network between Symbiodiniaceae and fungi in corals, which indicated that restricting fungal parasitism and strong interaction network resilience would promote heat acclimatization of corals. Accordingly, this study provides insights into the role of microorganisms and their interaction as drivers of interspecific differences in coral thermal bleaching.
Topics: Animals; Anthozoa; Coral Reefs; Dinoflagellida; Microbiota; Symbiosis; Fungi
PubMed: 38445866
DOI: 10.1128/aem.01939-23 -
Environmental Microbiology Reports Apr 2024Bacterial-algal interactions strongly influence marine ecosystems. Bacterial communities in cultured dinoflagellates of the family Symbiodiniaceae have been...
Bacterial-algal interactions strongly influence marine ecosystems. Bacterial communities in cultured dinoflagellates of the family Symbiodiniaceae have been characterized by metagenomics. However, little is known about whole-genome analysis of marine bacteria associated with these dinoflagellates. We performed in silico analysis of four bacterial genomes from cultures of four dinoflagellates of the genera Symbiodinium, Breviolum, Cladocopium and Durusdinium. Comparative analysis showed that the former three contain the alphaproteobacterial family Parvibaculaceae and that the Durusdinium culture includes the family Sphingomonadaceae. There were no large genomic reductions in the alphaproteobacteria with genome sizes of 2.9-3.9 Mb, implying they are not obligate intracellular bacteria. Genomic annotations of three Parvibaculaceae detected the gene for diacetylchitobiose deacetylase (Dac), which may be involved in the degradation of dinoflagellate cell surfaces. They also had metabolic genes for dissimilatory nitrate reduction to ammonium (DNRA) in the nitrogen (N) cycle and cobalamin (vitamin B ) biosynthetic genes in the salvage pathway. Those three characters were not found in the Sphingomonadaceae genome. Predicted biosynthetic gene clusters for secondary metabolites indicated that the Parvibaculaceae likely produce the same secondary metabolites. Our study suggests that the Parvibaculaceae is a major resident of Symbiodiniaceae cultures with antibiotics.
Topics: Ecosystem; Genome, Bacterial; Alphaproteobacteria; Anti-Bacterial Agents; Dinoflagellida; Sphingomonadaceae; Vitamin B 12
PubMed: 38444256
DOI: 10.1111/1758-2229.13238