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The Journal of Eukaryotic Microbiology Jul 2024The planktonic dinoflagellate Prorocentrum compressum is widespread in warm and temperate seas. A strain identified as P. cf. compressum BEA 0681B isolated from the...
The planktonic dinoflagellate Prorocentrum compressum is widespread in warm and temperate seas. A strain identified as P. cf. compressum BEA 0681B isolated from the island of Gran Canaria, NE Atlantic Ocean, showed a divergence in rDNA/ITS phylogenies with respect to P. compressum. The Canarian strain was oval, with an average length-to-width ratio of 1.35, smooth thecal surface with less than 150 thecal pores, including oblique pores, sometimes with a bifurcated opening. In contrast, P. compressum was rounder, with a length-to-width ratio < 1.2, with reticulate-foveate ornamentation and 200-300 pores per valve. We propose Prorocentrum canariense sp. nov. These species clustered as the most early-branching lineage in the clade Prorocentrum sensu stricto. Although this clade mainly contains planktonic species, the closer relatives were the benthic species P. tsawwassenense and P. elegans. Interestingly, P. compressum and P. canariense sp. nov. are widely distributed in temperate and warm seas without an apparent morphological adaptation to planktonic life. The formation of two concentric hyaline mucilaginous walls could contribute to this success. We discuss the use of Prorocentrum bidens to solve the nomenclature issue of P. compressum that was described citing a diatom as basionym.
PubMed: 38956983
DOI: 10.1111/jeu.13039 -
Toxins Jun 2024Despite the fact that the first red tide reported on the coasts of the Iberian Peninsula was due to , knowledge about their frequency and, particularly, about the...
Despite the fact that the first red tide reported on the coasts of the Iberian Peninsula was due to , knowledge about their frequency and, particularly, about the environmental conditions contributing to bloom initiation is still scarce. For this reason, bloom episodes were observed and studied in three Galician rias during the summer season based on the 1993-2008 record database period; additionally, samples were collected in summer 2008. Proliferations of occurred in the rias of Ares and Barqueiro in June and August, respectively, while in the Ria of Coruña, they persisted from the end of June to early September. Red tides developed when the surface temperature reached 17 °C, with "seasonal thermal window" conditions, and when salinities were ≥30, i.e., an "optimal salinity window"; when these parameters were lower than these thresholds, cyst germination decreased. A cyst transport mechanism from sediments to the surface must also exist; this mechanism was found to be natural (tidal currents) in the ria of Barqueiro or anthropogenic (dredging) in the rias of Ares and Coruña. Surface temperatures during summer were usually favorable for cyst germination (85 to 100%) during the 1993-2008 period; however, water temperatures below 10 m depth only rarely reached the 17 °C threshold (2 to 18%). During this 16-year period, dredging activities could explain 71% (Coruña) and 44% (Ares) of the recorded bloom events. When a bloom episode developed in early summer, favorable conditions did not lead to a new red tide, probably due to the lag period required by cysts for germination. Moreover, blooms did not develop when high densities of diatoms (>1,000,000 cells·L) remained in the water column as a result of summer upwelling pulses occurring in specific years. The temperature-sediment disturbance pattern found in this study provides a useful tool for the prevention of eventual risks resulting from red tides of this dinoflagellate.
Topics: Dinoflagellida; Spain; Harmful Algal Bloom; Temperature; Seasons; Environmental Monitoring; Seawater; Geologic Sediments; Salinity
PubMed: 38922174
DOI: 10.3390/toxins16060280 -
Marine Drugs Jun 2024Ichthyotoxic red tide is a problem that the world is facing and needs to solve. The use of antialgal compounds from marine macroalgae to suppress ichthyotoxic red tide...
Ichthyotoxic red tide is a problem that the world is facing and needs to solve. The use of antialgal compounds from marine macroalgae to suppress ichthyotoxic red tide is considered a promising biological control method. Antialgal substances were screened and isolated from , , , , , , and sp. to obtain new materials for the development of algaecides against ichthyotoxic red tide microalgae using bioactivity-guided isolation methods. The fractions of seven macroalgae exhibited selective inhibitory activities against and , of which the ethyl acetate fractions had the strongest and broadest antialgal activities for the two tested red tide microalgae. Their inhibitory effects on . and . were even stronger than that of potassium dichromate, such as ethyl acetate fractions of . , . , and sp. Thin-layer chromatography and ultraviolet spectroscopy were further carried out to screen the ethyl acetate fraction of sp. Finally, a new glycolipid derivative, 2--eicosanoyl-3--(6-amino-6-deoxy)--D-glucopyranosyl-glycerol, was isolated and identified from sp., and it was isolated for the first time from marine macroalgae. The significant antialgal effects of 2--eicosanoyl-3--(6-amino-6-deoxy)--D-glucopyranosyl-glycerol on . and . were determined.
Topics: Seaweed; Glycolipids; Harmful Algal Bloom; Microalgae; Dinoflagellida
PubMed: 38921590
DOI: 10.3390/md22060279 -
Marine Drugs May 2024Microalgae are currently considered an attractive source of highly valuable metabolites potentially exploitable as anticancer agents, nutraceuticals and cosmeceuticals...
Microalgae are currently considered an attractive source of highly valuable metabolites potentially exploitable as anticancer agents, nutraceuticals and cosmeceuticals and for bioenergy purposes. Their ease of culturing and their high growth rates further promote their use as raw material for the production of specialty products. In the present paper, we focused our attention on specific glycerol-based lipid compounds, monoacylglycerols (MAGs), which displayed in our previous studies a selective cytotoxic activity against the haematological U-937 and the colon HCT-116 cancer cell lines. Here, we performed a quali/quantitative analysis of MAGs and total fatty acids (FAs) along with a profiling of the main lipid classes in a panel of 12 microalgal species, including diatoms and dinoflagellates. Our results highlight an inter- and intraspecific variability of MAG profile in the selected strains. Among them, (strain FE7) has emerged as the most promising source for possible biotechnological production of MAGs.
Topics: Microalgae; Humans; Monoglycerides; Fatty Acids; Diatoms; Antineoplastic Agents; Cell Line, Tumor; Aquatic Organisms; Dinoflagellida; HCT116 Cells
PubMed: 38921569
DOI: 10.3390/md22060258 -
PeerJ 2024Bioluminescence is light chemically produced by an organism. It is widespread across all major marine phyla and has evolved multiple times, resulting in a high diversity...
Bioluminescence is light chemically produced by an organism. It is widespread across all major marine phyla and has evolved multiple times, resulting in a high diversity of spectral properties and first flash kinetic parameters (FFKP). The bioluminescence of a system is often a good proxy for planktonic biomass. The species-specific parameters of bioluminescent displays can be measured to identify species and describe planktonic biodiversity. Most bioluminescent organisms will flash when mechanically stimulated , when subjected to supra-threshold levels of shear stress. Here we compare first flash kinetic parameters such as flash duration, peak intensity, rise time, decay time, first-flash mechanically stimulated light and e-folding time obtained with the commercially available Underwater Bioluminescence Assessment Tool (UBAT). We provide descriptions of the first flash kinetic parameters of several species of dinoflagellates , , , , and two zooplankton (the ctenophore and the larvacean ). FFKPs are then compared and discussed using non-parametric analyses of variance (ANOVAs), hierarchical clustering and a linear discriminant analysis to assess the ability to use bioluminescence signatures for identification. Once the first flash kinetic parameters of a bioluminescent species have been described, it is possible to detect its presence using emissions collected by bathyphotometers. Assessing abundance and diversity of bioluminescent species may therefore be possible.
Topics: Zooplankton; Animals; Dinoflagellida; Biodiversity; Luminescent Measurements; Species Specificity
PubMed: 38881863
DOI: 10.7717/peerj.17516 -
Harmful Algae Jun 2024Microplastics are well known as contaminants in marine environments. With the development of biofilms, most microplastics will eventually sink and deposit in benthic...
Microplastics are well known as contaminants in marine environments. With the development of biofilms, most microplastics will eventually sink and deposit in benthic environment. However, little research has been done on benthic toxic dinoflagellates, and the effects of microplastics on benthic dinoflagellates are unknown. Prorocentrum lima is a cosmopolitan toxic benthic dinoflagellate, which can produce a range of polyether metabolites, such as diarrhetic shellfish poisoning (DSP) toxins. In order to explore the impact of microplastics on marine benthic dinoflagellates, in this paper, we studied the effects of polystyrene (PS) on the growth and toxin production of P. lima. The molecular response of P. lima to microplastic stress was analyzed by transcriptomics. We selected 100 nm, 10 μm and 100 μm PS, and set three concentrations of 1 mg L, 10 mg L and 100 mg L. The results showed that PS exposure had limited effects on cell growth, but increased the OA and extracellular polysaccharide content at high concentrations. After exposure to PS MPs, genes associated with DSP toxins synthesis, carbohydrate synthesis and energy metabolism, such as glycolysis, TCA cycle and pyruvate metabolism, were significantly up-regulated. We speculated that after exposure to microplastics, P. lima may increase the synthesis of DSP toxins and extracellular polysaccharides, improve the level of energy metabolism and gene expression of ABC transporter, thereby protecting algal cells from damage. Our findings provide new insights into the effects of microplastics on toxic benthic dinoflagellates.
Topics: Dinoflagellida; Polystyrenes; Microplastics; Marine Toxins; Water Pollutants, Chemical; Transcriptome
PubMed: 38876530
DOI: 10.1016/j.hal.2024.102652 -
Harmful Algae Jun 2024Ostreopsis spp. blooms have been occurring in the last two decades in the Mediterranean Sea in association with a variety of biotic and abiotic substrata (macroalgae,...
Ostreopsis spp. blooms have been occurring in the last two decades in the Mediterranean Sea in association with a variety of biotic and abiotic substrata (macroalgae, seagrasses, benthic invertebrates, sand, pebbles and rocks). Cells proliferate attached to the surfaces through mucilaginous trichocysts, which lump together microalgal cells, and can also be found in the plankton and on floating aggregates: such tychoplanktonic behavior makes the quantitative assessment of blooms more difficult than planktonic or benthic ones. Different techniques have been so far applied for quantifying cell abundances of benthic microalgae for research, monitoring and risk assessment purposes. In this context, the Benthic Dinoflagellates Integrator (BEDI), a non-destructive quantification method for benthic dinoflagellate abundances, was developed and tested within the EU ENPI-CBCMED project M3-HABs. This device allows mechanical detachment of cells without collecting the benthic substrate, providing an integrated assessment of both epiphytic and planktonic cells, i.e. of the number of cells potentially made available in the water volume from "resuspension" which could have harmful effects on other organisms (including humans). The present study confirms the effectiveness of the BEDI sampling device across different environments across the Mediterranean Sea and constitutes the first large-scale study of Ostreopsis spp. blooms magnitude in function of different macro- and meso‑habitat features across the basin.
Topics: Dinoflagellida; Mediterranean Sea; Harmful Algal Bloom; Environmental Monitoring; Microalgae; Seawater
PubMed: 38876529
DOI: 10.1016/j.hal.2024.102651 -
Harmful Algae Jun 2024Harmful Algal Blooms (HABs) are increasing in temperate areas, and the growth rates of benthic harmful dinoflagellates may be favoured in the context of global climate...
Harmful Algal Blooms (HABs) are increasing in temperate areas, and the growth rates of benthic harmful dinoflagellates may be favoured in the context of global climate change. Benthic dinoflagellates, including species belonging to the Ostreopsis Schmidt genus, are known to develop on the surface of macroalgae and different macroalgal morphotypes and communities could host higher or lower cell abundances. The physical structure of the macroalgal substrate at the small scale (cm, microhabitat scale) and the structural complexity of the macroalgal community at the medium scale (few m, mesohabitat scale) could play a relevant role in bloom facilitation: the hypothesis that Ostreopsis species could be associated with macroalgal turfs and shrubs, structurally less complex communities than canopy-forming macroalgae, is especially under discussion and, if confirmed, could link bloom occurrence to regime shifts in temperate ecosystems. The present study, performed in two locations of the Ligurian Sea (Rochambeau, France and Vernazzola, Italy) aimed at understanding marine vegetation's role at the micro and mesohabitat scales in controlling the distribution and abundance of Ostreopsis. The abundance of the microalgal cells was quantified at different spatial scales, from cm to a few m, on different macroalgal species and communities, including artificial substrates, to tease apart the micro and mesohabitat effects. The results obtained show a high spatio-temporal variability, potentially hiding habitat-related patterns. The substrate's preferences diminish when cell abundances are very high, as in the case of Rochambeau, while in presence of moderate cell abundances as in Vernazzola or the first phases of blooms, it is possible to appreciate differences in abundances among substrates (in our study, Dictyota fasciola (Roth) Lamouroux supporting higher abundances). Our results open new research topics such as the study of blooms at a larger scale (macrohabitat) and testing different sampling methods to standardise the cells' abundances independently on the substrate.
Topics: Harmful Algal Bloom; Dinoflagellida; Seaweed; Italy; France; Ecosystem
PubMed: 38876526
DOI: 10.1016/j.hal.2024.102650 -
Harmful Algae Jun 2024This study aimed to explore the effects of different light intensities on the ecophysiology of eight new Dinophysis isolates comprising four species (D. acuminata, D....
This study aimed to explore the effects of different light intensities on the ecophysiology of eight new Dinophysis isolates comprising four species (D. acuminata, D. ovum, D. fortii, and D. caudata) collected from different geographical regions in the US. After six months of acclimation, the growth rates, photosynthetic efficiency (F/F ratio), toxin content, and net toxin production rates of the Dinophysis strains were examined. The growth rates of D. acuminata and D. ovum isolates were comparable across light intensities, with the exception of one D. acuminata strain (DANY1) that was unable to grow at the lowest light intensity. However, D. fortii and D. caudata strains were photoinhibited and grew at a slower rate at the highest light intensity, indicating a lower degree of adaptability and tolerance to such conditions. Photosynthetic efficiency was similar for all Dinophysis isolates and negatively correlated with exposure to high light intensities. Multiple toxin metrics, including cellular toxin content and net production rates of DSTs and PTXs, were variable among species and even among isolates of the same species in response to light intensity. A pattern was detected, however, whereby the net production rates of PTXs were significantly lower across all Dinophysis isolates when exposed to the lowest light intensity. These findings provide a basis for understanding the effects of light intensity on the eco-physiological characteristics of Dinophysis species in the US and could be employed to develop integrated physical-biological models for species and strains of interest to predict their population dynamics and mitigate their negative effects.
Topics: Photosynthesis; Light; Dinoflagellida; Acclimatization; Marine Toxins; Species Specificity
PubMed: 38876524
DOI: 10.1016/j.hal.2024.102624 -
The Science of the Total Environment Sep 2024Global warming has been shown to harmfully affect symbiosis between Symbiodiniaceae and other marine invertebrates. When symbiotic dinoflagellates (the genus Breviolum)...
Global warming has been shown to harmfully affect symbiosis between Symbiodiniaceae and other marine invertebrates. When symbiotic dinoflagellates (the genus Breviolum) were in vitro exposed to acute heat stress of +7 °C for a period of 5 days, the results revealed the negative impact on all physiological and other cellular parameters measured. Elevated temperatures resulted in a severe reduction in algal density of up to 9.5-fold, as well as pigment concentrations, indicating the status of the physiological stress and early signs of photo-bleaching. Reactive oxygen species (ROS) were increased in all heated dinoflagellate cells, while the antioxidant-reduced glutathione levels initially dropped on day one but increased under prolonged temperature stress. The cell viability parameters were reduced by 97 % over the heating period, with an increased proportion of apoptotic and necrotic cells. Autofluorescence (AF) for Cy5-PE 660-20 was reduced from 1.7-fold at day 1 to up to 50-fold drop at the end of heating time, indicating that the AF changes were highly sensitive to heat stress and that it could be an extremely sensitive tool for assessing the functionality of algal photosynthetic machinery. The addition of the drug 5-AZA-2'-deoxycytidine (5-AZA), which inhibits DNA methylation processes, was assessed in parallel and contributed to some alterations in algal cellular stress response. The presence of drug 5-AZA combined with the temperature stress had an additional impact on Symbiodiniaceae density and cell complexity, including the AF levels. These variations in cellular stress response under heat stress and compromised DNA methylation conditions may indicate the importance of this epigenetic mechanism for symbiotic dinoflagellate thermal tolerance adaptability over a longer period, which needs further exploration. Consequently, the increased ROS levels and changes in AF signals reported during ongoing heat stress in dinoflagellate cells could be used as early stress biomarkers in these microalgae and potentially other photosynthetic species.
Topics: Dinoflagellida; Oxidative Stress; Heat-Shock Response; Symbiosis; Reactive Oxygen Species; Hot Temperature
PubMed: 38866148
DOI: 10.1016/j.scitotenv.2024.173916