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Harmful Algae Apr 2024In the North Sea, Tripos and Dinophysis are commonly occurring mixotrophic planktonic dinoflagellate genera. In order to understand their bloom dynamics, an occurring...
In the North Sea, Tripos and Dinophysis are commonly occurring mixotrophic planktonic dinoflagellate genera. In order to understand their bloom dynamics, an occurring bloom dominated by T. furca and D. norvegica was followed for several days. High cell abundances of these species were located to estimate: in situ growth rates from cell cycle analyses, depth distributions, growth rates sustained by photosynthesis, and parasite infection prevalence in all T. furca, T. fusus, D. norvegica and D. acuminata. Cell abundances were over 10000 cells L for T. furca and up to 18000 cells L for D. norvegica. Cells accumulated between 15-25 m depth and presented low specific in situ growth rates of 0.04-0.15 d for T. furca and 0.02-0.16 d for D. norvegica. Photosynthesis could sustain growth rates of 0.01-0.18 d for T. furca and 0.02 to 0.14 d for D. norvegica, suggesting that these species were relying mainly on photosynthesis. Parasite infections where generally low, with occasional high prevalence in D. norvegica (by Parvilucifera sp.) and T. fusus (by Amoebophrya sp.), while both parasites showed comparable prevalence in D. acuminata, which could offset in situ growth rates by parasite-induced host mortality. The restructuring effect of parasites on dinoflagellate blooms is often overlooked and this study elucidates their effect to cell abundances and their growth at the final stages of a bloom.
Topics: Dinoflagellida; Photosynthesis; North Sea; Population Dynamics; Harmful Algal Bloom
PubMed: 38705610
DOI: 10.1016/j.hal.2024.102604 -
Harmful Algae Apr 2024Toxic dinoflagellate Alexandrium can produce saxitoxins (STXs) and cause paralytic shellfish poisoning (PSP), and thus they are monitored for environmental safety...
Development of saxitoxin biosynthesis gene sxtB-targeted qPCR assay for the quantification of toxic dinoflagellates Alexandrium catenella (group I) and A. pacificum (group IV) occurring in the Korean coast.
Toxic dinoflagellate Alexandrium can produce saxitoxins (STXs) and cause paralytic shellfish poisoning (PSP), and thus they are monitored for environmental safety management. Microscopic discrimination of dinoflagellates is difficult to distinguish between toxic and non-toxic species due to their similar morphology. Meanwhile, an alternative quantitative PCR (qPCR) assay is sensitive, rapid, and cost-effective for harmful species monitoring. Herein, we developed a novel qPCR assay to detect the STXs biosynthesis gene sxtB of Alexandrium catenella and A. pacificum, the leading cause of PSP outbreaks in Asian coasts and worldwide. The newly designed sxtB TaqMan probes target the species without any positive signal in other relative dinoflagellates. Deming regression analysis revealed that the sxtB copy number of A. catenella and A. pacificum was 3.6 and 4.1 copies per cell, respectively. During the blooming periods (April 13-14, 2020), only A. catenella cells were detected through the qPCR assay, ranging from 5.0 × 10 to 2.5 × 10 eq cells L. In addition, sxtB qPCR quantified more accurately compared to large subunit (LSU) rRNA targeting qPCR assay that overestimate cell density. Besides, the sensitivity of sxtB was higher compared to the microscope when the species were rarely present (5.0 × 10 cells L). These suggest that the sxtB qPCR assay can be applied to toxic Alexandrium monitoring in the Korean coast, even in the early stage of bloomings.
Topics: Dinoflagellida; Saxitoxin; Republic of Korea; Real-Time Polymerase Chain Reaction; Harmful Algal Bloom
PubMed: 38705609
DOI: 10.1016/j.hal.2024.102603 -
Environmental Pollution (Barking, Essex... Jun 2024Nutrient reduction is an essential environmental policy for water quality remediation, but climate change can offset the ecological benefits of nutrient reduction and...
Nutrient reduction is an essential environmental policy for water quality remediation, but climate change can offset the ecological benefits of nutrient reduction and lead to the difficulty of environmental evaluation. Here, based on the records of three lipid microalgal biomarkers and stable isotopes of carbon and nitrogen in two sediment cores from the embayment of Perth, Australia, we reconstructed the microalgal biomasses (diatoms, dinoflagellates and coccolithophores) over the past century and evaluated the ecological effects of nutrient reduction on them, using Change Point Modeling (CPM) and redundancy analysis (RDA). The CPM result showed that total microalgal biomarkers increased by 25% and 51% in deep and shallow areas, respectively, due to nutrient enrichment caused by industrial wastewater in the 1950s and the causeway construction in the 1970s, and dinoflagellates were beneficiaries of eutrophication. The nutrient reduction policy since the 1980s had not decreased total microalgal biomass, and diatoms were beneficiaries of this period. RDA based on time series of sediment cores and water monitoring data revealed that the increase of sea-surface temperature and the decrease of rainfall since the 1980s may be important factors sustaining the high total microalgal biomass and increasing the degree of diatom dominance. The result also indicated that the variations of microalgal assemblages may better explain the effect of nutrient reduction rather than total microalgal biomass.
Topics: Microalgae; Water Quality; Environmental Restoration and Remediation; Eutrophication; Australia; Environmental Monitoring; Diatoms; Biomass; Dinoflagellida; Seawater; Climate Change; Nitrogen; Geologic Sediments; Water Pollutants, Chemical
PubMed: 38685553
DOI: 10.1016/j.envpol.2024.124017 -
Pesticide Biochemistry and Physiology May 2024The dinoflagellate Karenia brevis is a causative agent of red tides in the Gulf of Mexico and generates a potent family of structurally related brevetoxins that act via...
The dinoflagellate Karenia brevis is a causative agent of red tides in the Gulf of Mexico and generates a potent family of structurally related brevetoxins that act via the voltage-sensitive Na channel. This project was undertaken to better understand the neurotoxicology and kdr cross-resistance to brevetoxins in house flies by comparing the susceptible aabys strain to ALkdr (kdr) and JPskdr (super-kdr). When injected directly into the hemocoel, larvae exhibited rigid, non-convulsive paralysis consistent with prolongation of sodium channel currents, the known mechanism of action of brevetoxins. In neurophysiological studies, the firing frequency of susceptible larval house fly central nervous system preparations showed a > 200% increase 10 min after treatment with 1 nM brevetoxin-3. This neuroexcitation is consistent with the spastic paralytic response seen after hemocoel injections. Target site mutations in the voltage-sensitive sodium channel of house flies, known to confer knockdown resistance (kdr and super-kdr) against pyrethroids, attenuated the effect of brevetoxin-3 in baseline firing frequency and toxicity assays. The rank order of sensitivity to brevetoxin-3 in both assays was aabys > ALkdr > JPskdr. At the LD level, resistance ratios for the knockdown resistance strains were 6.9 for the double mutant (super-kdr) and 2.3 for the single mutant (kdr). The data suggest that knockdown resistance mutations may be one mechanism by which flies survive brevetoxin-3 exposure during red tide events.
Topics: Animals; Oxocins; Mutation; Marine Toxins; Houseflies; Larva; Dinoflagellida; Polyether Toxins
PubMed: 38685256
DOI: 10.1016/j.pestbp.2024.105898 -
Molecular Phylogenetics and Evolution Jul 2024Dinoflagellates are diverse and ecologically important protists characterized by many morphological and molecular traits that set them apart from other eukaryotes. These...
Dinoflagellates are diverse and ecologically important protists characterized by many morphological and molecular traits that set them apart from other eukaryotes. These features include, but are not limited to, massive genomes organized using bacterially-derived histone-like proteins (HLPs) and dinoflagellate viral nucleoproteins (DVNP) rather than histones, and a complex history of photobiology with many independent losses of photosynthesis, numerous cases of serial secondary and tertiary plastid gains, and the presence of horizontally acquired bacterial rhodopsins and type II RuBisCo. Elucidating how this all evolved depends on knowing the phylogenetic relationships between dinoflagellate lineages. Half of these species are heterotrophic, but existing molecular data is strongly biased toward the photosynthetic dinoflagellates due to their amenability to cultivation and prevalence in culture collections. These biases make it impossible to interpret the evolution of photosynthesis, but may also affect phylogenetic inferences that impact our understanding of character evolution. Here, we address this problem by isolating individual cells from the Salish Sea and using single cell, culture-free transcriptomics to expand molecular data for dinoflagellates to include 27 more heterotrophic taxa, resulting in a roughly balanced representation. Using these data, we performed a comprehensive search for proteins involved in chromatin packaging, plastid function, and photoactivity across all dinoflagellates. These searches reveal that 1) photosynthesis was lost at least 21 times, 2) two known types of HLP were horizontally acquired around the same time rather than sequentially as previously thought; 3) multiple rhodopsins are present across the dinoflagellates, acquired multiple times from different donors; 4) kleptoplastic species have nucleus-encoded genes for proteins targeted to their temporary plastids and they are derived from multiple lineages, and 5) warnowiids are the only heterotrophs that retain a whole photosystem, although some photosynthesis-related electron transport genes are widely retained in heterotrophs, likely as part of the iron-sulfur cluster pathway that persists in non-photosynthetic plastids.
Topics: Dinoflagellida; Phylogeny; Photosynthesis; Heterotrophic Processes; Biological Evolution; Evolution, Molecular; Plastids
PubMed: 38677354
DOI: 10.1016/j.ympev.2024.108086 -
Marine Pollution Bulletin May 2024Red Noctiluca scintillans (RNS), a prominent species of dinoflagellate known for its conspicuous size and ability to form blooms, exhibits heterotrophic behavior and...
Red Noctiluca scintillans (RNS), a prominent species of dinoflagellate known for its conspicuous size and ability to form blooms, exhibits heterotrophic behavior and functions as a microzooplankton grazer within the marine food web. In this study, a straightforward technique referred to as the blue-green index (BGI) has been introduced for the purpose of distinguishing and discerning RNS from neighboring waters, owing to its pronounced absorption in the blue-green spectral range. This method has been applied across a range of satellite imagery, encompassing both multi-spectral and hyperspectral sensors. The study delved into three instances of bloom occurrences caused by RNS: firstly, in November 2014 and April 2022 off the western coast of Guangdong, and secondly, in February 2021 within the Beibu Gulf. The notable bloom event in the Beibu Gulf during February 2021 extended across an expansive area totaling 6933.5 km. The motion speed and direction of the RNS bloom patches were also derived from successive satellite images. The recently introduced BGI method demonstrates insensitivity to suspended sediment, though its successful application necessitates accurate atmospheric correction. Subsequent efforts will involve the quantification of RNS blooms in a more precise manner, utilizing hyperspectral satellite data grounded in optimized band configurations.
Topics: Dinoflagellida; Satellite Imagery; Environmental Monitoring; Eutrophication
PubMed: 38669852
DOI: 10.1016/j.marpolbul.2024.116377 -
Scientific Data Apr 2024Prorocentrum shikokuense (formerly P. donghaiense) is a pivotal dinoflagellate species associating with the HABs in the East China Sea. The complexity of its large...
Prorocentrum shikokuense (formerly P. donghaiense) is a pivotal dinoflagellate species associating with the HABs in the East China Sea. The complexity of its large nuclear genome hindered us from understanding its genomic characteristics. Full-length transcriptome sequencing offers a practical solution to decipher the physiological mechanisms of a species without the reference genome. In this study, we employed single-molecule real-time (SMRT) sequencing technology to sequence the full-length transcriptome of Prorocentrum shikokuense. We successfully generated 41.73 Gb of clean SMRT sequencing reads and isolated 105,249 non-redundant full-length non-chimeric reads. Our trial has led to the identification of 11,917 long non-coding RNA transcripts, 514 alternative splicing events, 437 putative transcription factor genes from 17 TF gene families, and 34,723 simple sequence repeats. Additionally, a total of 78,265 open reading frames were identified, of them 15,501 were the protein coding sequences. This dataset is valuable for annotating P. shikokuense genome, and will contribute significantly to the in-depth studies on the molecular mechanisms underlining the dinoflagellate bloom formation.
Topics: Alternative Splicing; China; Dinoflagellida; Gene Expression Profiling; Open Reading Frames; Transcription Factors; Transcriptome; Eutrophication
PubMed: 38664437
DOI: 10.1038/s41597-024-03269-1 -
Marine Environmental Research Jun 2024Diatoms and dinoflagellates are two typical functional groups of phytoplankton assemblages, which play a crucial role in the structure and functioning of most marine...
Diatoms and dinoflagellates are two typical functional groups of phytoplankton assemblages, which play a crucial role in the structure and functioning of most marine ecosystems. To date, a novel challenge in ecology and biogeochemistry is to address the influences of environmental changes associated with climate change and human activities on the dynamics of diatoms and dinoflagellates. However, the knowledge of the key environmental factors controlling the diatom-dinoflagellate dynamics remains to be improved, particularly in the coastal ecosystems. Therefore, we conducted four cruises along the Qingdao coastline in spring, summer, autumn, and winter 2022 to explore how diatoms and dinoflagellates varied in response to regional environmental changes. The results showed that the phytoplankton communities were dominated by diatoms and dinoflagellates in terms of abundance and species diversity throughout the year in the study region. Yet, there were significant seasonal variability of diatoms and dinoflagellates across the four seasons. For example, diatom species was the most diverse during autumn, and the higher average abundance was observed in the fall and winter. In contrast, the average abundance of dinoflagellates was maximum during the summer and minimum in the autumn season. Moreover, the abundance and species ratios of diatoms/dinoflagellates (dia/dino) also showed significant seasonal variations in the region. The dia/dino abundance ratio was lowest in summer, while the dia/dino species ratio showed an increasing trend from spring to fall and a slight descending trend during winter. Based on the redundancy analysis, we revealed that diatoms and dinoflagellates responded differently to various environmental variables in different seasons, of which temperature and nutrients (especially dissolved inorganic nitrogen, DIN) had highly significant correlations with both the dia/dino abundance and species ratios. Thus, we suggested that temperature and DIN were the key factors controlling the seasonal dynamics of diatoms and dinoflagellates in the Qingdao coastal area.
Topics: Dinoflagellida; Diatoms; Seasons; China; Climate Change; Phytoplankton; Environmental Monitoring; Ecosystem; Biodiversity
PubMed: 38664079
DOI: 10.1016/j.marenvres.2024.106524 -
The ISME Journal Jan 2024Dinoflagellates in the family Symbiodiniaceae are taxonomically diverse, predominantly symbiotic lineages that are well-known for their association with corals. The...
Dinoflagellates in the family Symbiodiniaceae are taxonomically diverse, predominantly symbiotic lineages that are well-known for their association with corals. The ancestor of these taxa is believed to have been free-living. The establishment of symbiosis (i.e. symbiogenesis) is hypothesized to have occurred multiple times during Symbiodiniaceae evolution, but its impact on genome evolution of these taxa is largely unknown. Among Symbiodiniaceae, the genus Effrenium is a free-living lineage that is phylogenetically positioned between two robustly supported groups of genera within which symbiotic taxa have emerged. The apparent lack of symbiogenesis in Effrenium suggests that the ancestral features of Symbiodiniaceae may have been retained in this lineage. Here, we present de novo assembled genomes (1.2-1.9 Gbp in size) and transcriptome data from three isolates of Effrenium voratum and conduct a comparative analysis that includes 16 Symbiodiniaceae taxa and the other dinoflagellates. Surprisingly, we find that genome reduction, which is often associated with a symbiotic lifestyle, predates the origin of Symbiodiniaceae. The free-living lifestyle distinguishes Effrenium from symbiotic Symbiodiniaceae vis-à-vis their longer introns, more-extensive mRNA editing, fewer (~30%) lineage-specific gene sets, and lower (~10%) level of pseudogenization. These results demonstrate how genome reduction and the adaptation to distinct lifestyles intersect to drive diversification and genome evolution of Symbiodiniaceae.
Topics: Dinoflagellida; Symbiosis; Phylogeny; Evolution, Molecular; Transcriptome; Genome, Protozoan
PubMed: 38655774
DOI: 10.1093/ismejo/wrae059 -
Ying Yong Sheng Tai Xue Bao = the... Mar 2024To explore the causes of red tides in Qinhuangdao coastal water, we conducted surveys on both water quality and red tides during April to September of 2022 and analyzed...
To explore the causes of red tides in Qinhuangdao coastal water, we conducted surveys on both water quality and red tides during April to September of 2022 and analyzed the relationships between main environmental factors and red tide organisms through the factor analysis and canonical correspondence analysis. The results showed that there were eight red tides along the coast of Qinhuangdao in 2022, with a cumulative blooming area of 716.1 km. The red tides could be divided into three kinds based on the major blooming organisms and occurrence time, bloom, diatom-euglena (, , spp.) bloom, and dinoflagellate ( and ) bloom. Seasonal factor played roles mainly during July to September, while inorganic nutrients including nitrogen and phosphorus influenced the blooms mainly in April and July. The canonical correspondence analysis suggested that preferred low temperature, and often bloomed with high concentrations of ammonium nitrogen and dissolved inorganic phosphorus. , , and spp. could tolerate broad ranges of various environmental factors, but favored high temperature and nitrogen-rich seawater. and had higher survival rate and competitiveness in phosphate-poor waters. Combined the results from both analyses, we concluded that the causes for the three kinds of red tide processes in Qinhuangdao coastal areas in 2022 were different. Adequate diet algae and appropriate water temperature were important factors triggering and maintaining the bloom. Suitable temperature, salinity and eutrophication were the main reasons for the diatom-euglena bloom. The abundant nutrients and seawater disturbance promoted the germination of cysts, while phosphorus limitation caused the blooming organism switched to and maintained the bloom hereafter.
Topics: China; Dinoflagellida; Seawater; Diatoms; Harmful Algal Bloom; Environmental Monitoring; Oceans and Seas; Phosphorus; Nitrogen; Seasons
PubMed: 38646770
DOI: 10.13287/j.1001-9332.202403.029