Search Results (19)

Invasive species can alter community composition and ecosystem functioning. In the subtidal rocky shores of Arraial do Cabo Bay, southeastern Brazil, the invasive coral Tubastraea spp. has established populations, raising concerns about long-term impacts on native benthic communities. This study investigates temporal shifts in β-diversity across 44 fixed plots containing Tubastraea spp., monitored over 383 days. Underwater photographic surveys and multivariate analyses identified nine distinct benthic community types, each forming mosaic structures of sessile organisms. Temporal β-diversity analyses revealed that only the group characterized by Tubastraea, crustose calcareous algae and the zoantharian Palythoa caribaeorum showed significant differences between species gains and losses over time, suggesting temporal-scale dependency. Key contributors to community dissimilarity included P. caribaeorum, crustose calcareous algae, turf, the sponge genus Darwinella, and Tubastraea. This study highlights the importance of considering both spatial and temporal heterogeneity when assessing the ecological impact of marine invasive species. Our findings underscore the need for multi-scale monitoring to fully understand the dynamics of tropical subtidal ecosystems under biological invasion. While numerous studies report a correlation between Tubastraea abundance and shifts in ecological diversity, this relationship may be weak, as critical drivers such as the complexity of community organization are rarely accounted for. Full article

Recreational diving depends on healthy marine ecosystems, yet it can harm biodiversity through species displacement and habitat damage. Bombinhas, a biodiverse diving hotspot in southern Brazil, faces growing threats from human activity and climate change. This study assessed the ecological structure of Sepultura Beach (2018) for potential diving trails, comparing it with historical data from Porto Belo Island. Using visual censuses, transects, and photo-quadrats across six sampling campaigns, researchers documented 2419 organisms from five zoological groups, identifying 14 dominant species, including Haemulon aurolineatum and Diplodus argenteus. Cluster analysis revealed three ecological zones, with higher biodiversity at the site’s edges (Groups 1 and 3), but these areas also hosted endangered species like Epinephelus marginatus, complicating trail planning. A major concern was the widespread bleaching of the zoanthid Palythoa caribaeorum, a key ecosystem engineer, likely due to rising sea temperatures (+1.68 °C from 1961–2018) and declining chlorophyll-a levels post-2015. Comparisons with past data showed a 0.33 °C increase in species’ thermal preferences over 17 years, alongside lower trophic levels and greater ecological vulnerability, indicating tropicalization from the expanding Brazil Current. While Sepultura Beach’s biodiversity supports diving tourism, conservation efforts must address coral bleaching and endangered species protection. Long-term monitoring is crucial to track warming impacts, and adaptive management is needed for sustainable trail development. The study highlights the urgent need to balance ecotourism with climate resilience in subtropical marine ecosystems. Full article

Palytoxins are a group of highly potent and structurally complex marine toxins that rank among some of the most toxic substances known to science. Palytoxins are naturally synthesized by a variety of marine organisms, including Palythoa zoanthids, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria, and are widely distributed in tropical and temperate regions where they can bioaccumulate in marine life. The evolution of research on palytoxins has been an intricate exchange between interdisciplinary fields, drawing insights from chemistry, biology, medicine, and environmental science in efforts to better understand and mitigate the health risks associated with this family of toxins. In this review, we begin with a brief history covering the discovery of this group of toxins and the events that led to its isolation. We then focus on the chemical structure of these compounds and their proposed mechanism of action. Finally, we review in vitro, ex vivo, and in vivo studies related to their toxicity, with the aim to provide a broad overview of the current knowledge on palytoxin toxinology. Full article

As the global sea surface water temperature increases due to climate change, some zooxanthellate species have extended their habitat range to higher latitudes. Palythoa species, a colonial zooxanthellate cnidarian, is one such example of a range-extending animal. Recently, massive colonies of zoantharians that appeared to be of Palythoa spp. were discovered in a subtidal area of southern Jeju Island. Because a zoantharian-dominated ecosystem could indicate an unhealthy status, the documentation of its occurrence and species identification are crucial for subsequent studies. In this study, we report and confirm the presence of massive Palythoa colonies in Taeheung and Topyeong, off the southern coast of Jeju Island, using in situ underwater images and identify the species by sequencing the internal transcribed spacer rDNA. The resulting Bayesian inference tree clearly demonstrates that the massive colonies consist of Palythoa mutuki and are closely related to P. mutuki collected from the Ryukyu Archipelago in southern Japan. These records provide evidence of the northward expansion of subtropical and tropical marine organisms. Full article

Palytoxin (PLTX) and its analogues are marine polyethers identified in Palythoa and Zoanthus corals, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria. Humans can be exposed to these toxins by different routes with a series of adverse effects but the most severe risk is associated with poisonings by the consumption of edible marine organisms accumulating these toxins, as occurs in (sub)-tropical areas. In temperate areas, adverse effects ascribed to PLTXs have been recorded after inhalation of marine aerosols and/or cutaneous contact with seawater during Ostreopsis blooms, as well as during cleaning procedures of Palythoa-containing home aquaria. Besides instrumental analytical methods, in the last years a series of alternative or complementary methods based on biological/biochemical tools have been developed for the rapid and specific PLTX detection required for risk assessment. These methods are usually sensitive, cost- and time-effective, and do not require highly specialized operators. Among them, structural immunoassays and functional cell-based assays are reviewed. The availability of specific anti-PLTX antibodies allowed the development of different sensitive structural assays, suitable for its detection also in complex matrices, such as mussels. In addition, knowing the mechanism of PLTX action, a series of functional identification methods has been developed. Despite some of them being limited by matrix effects and specificity issues, biological methods for PLTX detection represent a feasible tool, suitable for rapid screening. Full article

The white encrusting zoanthid Palythoa caribaeorum is known to form large colonies, which serve as aggregators of marine fauna. In Porto Belo, south Brazil (27.158° S, 48.553° W), the fish community was more abundant over P. caribaeorum grounds and more diverse, as described by traditional ecological descriptors, beta-diversity index, and discriminant analysis. In addition to its important ecological role, it is of great economic relevance, as it is conducive to the establishment of underwater diving trails. In the last 20 years, however, the bleaching of this zoanthid was observed within the study area. As suggested in the literature, we evaluated environmental temperature from three different sources: 1. Meteorological stations (MS) between 1961 and 2019; 2. Satellite images (SI) (1993–2019), and 3. Water temperature (WT) obtained in situ with dive computers, between February and September 2018. Initially, a Pearson correlation coefficient was calculated for temperature values obtained in MS and by SI (between 1993 and 2018) and between temperature values obtained by SI and by dive computers (February to September 2018—WT). Subsequently, the temperatures obtained in MS and in SI were standardized in additive generalized models for location scale and shape. The temperature values obtained in MS and by SI showed perfect correlation (R = 1). In the comparison between temperature values obtained by SI and WT, the correlation coefficient was 0.92, indicating that air, sea surface, and water temperatures showed the same increasing trend. The adjusted temperature values for the weather stations showed an average increase of 1.68 °C between 1961 and 2018 and 0.64 °C between 1993 and 2018 for the values adjusted from SI. The results obtained in a distance-based redundancy analysis showed the spatial distribution of fish species sighted at Porto Belo during the monitoring conducted between February and September 2018 was significant for the preferred temperature of these species. Despite the lack of available estimates for preferential temperature of P. caribaeorum, this progressive increase in temperature is one of the main causes for the bleaching of several coral species, as reported in the literature. Full article

Palytoxin (PLTX) is a highly toxic polyether identified in various marine organisms, such as Palythoa soft corals, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria. In addition to adverse effects in humans, negative impacts on different marine organisms have been often described during Ostreopsis blooms and the concomitant presence of PLTX and its analogues. Considering the increasing frequency of Ostreopsis blooms due to global warming, PLTX was investigated for its effects on Artemia franciscana, a crustacean commonly used as a model organism for ecotoxicological studies. At concentrations comparable to those detected in culture media of O. cf. ovata (1.0–10.0 nM), PLTX significantly reduced cysts hatching and induced significant mortality of the organisms, both at larval and adult stages. Adults appeared to be the most sensitive developmental stage to PLTX: significant mortality was recorded after only 12 h of exposure to PLTX concentrations > 1.0 nM, with a 50% lethal concentration (LC₅₀) of 2.3 nM (95% confidence interval = 1.2–4.7 nM). The toxic effects of PLTX toward A. franciscana adults seem to involve oxidative stress induction. Indeed, the toxin significantly increased ROS levels and altered the activity of the major antioxidant enzymes, in particular catalase and peroxidase, and marginally glutathione-S-transferase and superoxide dismutase. On the whole, these results indicate that environmentally relevant concentrations of PLTX could have a negative effect on Artemia franciscana population, suggesting its potential ecotoxicological impact at the marine level. Full article

Leishmaniasis and Chagas disease are neglected tropical diseases that cause problems in developing countries. The causative agents, Leishmania spp. and Trypanosoma cruzi, produce a clinical picture that can be fatal for the patient, such as Chagas heart disease, visceral leishmaniasis and megacolon, among others. Current treatments for these diseases are not very effective and highly toxic, since they require very prolonged treatments. The development of innovative, effective and safe drugs to fight infections caused by these parasites remains a challenge. For this reason, in recent years, there has been an increase in the search for new therapies. In this study, the antikinetoplastid activity of 13 sesquiterpene lactones obtained from Palythoa aff. clavata was screened against L. amazonensis, L. donovani and T. cruzi. The results revealed that the sesquiterpene lactones anhydroartemorin (2), cis,trans-costunolide-14-acetate (3) and 4-hydroxyarbusculin A (11) were the most selective against the kinetoplastid species studied. These molecules seem to induce the mechanisms involved in an apoptotic-like death or programmed cell death (PCD) in the kinetoplastids, and since they do not cause necrosis, the inflammatory events associated with this type of cell death will not be triggered. Full article

Zoantharians are colonial cnidarians commonly found in shallow tropical Caribbean coral reefs, and are known to be globally distributed. Common species in genera Zoanthus and Palythoa occur at Toco, Trinidad, where they are more abundant than their Scleractinia counterparts relative to benthic coverage. In this study, distribution, morphological and molecular data were collected to determine species and symbiont identification to provide more insight on zoantharians. The Line Intercept Point (LIT) transect method recorded coverage at three sites: Salybia (SB), Pequelle (PB), and Grande L’Anse (GA) Bays along the northeastern coast. Variations in morphology, such as tentacle count, oral disk color and diameter were collected from colonies in situ. All specimens were zooxanthellate, and molecular and phylogenetic analyses were done by sequencing the cytochrome oxidase subunit I (COI) gene, and the internal transcribed spacer (ITS) region for species and symbiont identification, respectively. Results showed mean Zoantharia percentage cover was 32.4% ± 5.1 (X ± SE) at SB, 51.3% ± 6.5 (PB), and 72.2% ± 6.1 at GA. Zooxanthellate zoantharians were identified as Palythoa caribaeorum, Palythoa grandiflora, Zoanthus pulchellus, and Zoanthus sociatus. Symbiodiniaceae genera were identified as Cladocopium and Symbiodinium in Palythoa and Zoanthus spp., respectively. Although this is the first molecular examination of zoantharians, and their symbionts in Trinidad, more research is needed to identify and document species distribution and symbiont biodiversity to understand their ecology in these dynamic ecosystems. Full article

Zoanthids of the genus Palythoa are distributed worldwide in shallow waters around coral reefs. Like all cnidarians, they possess nematocysts that contain a large diversity of toxins that paralyze their prey. This work was aimed at isolating and functionally characterizing a cnidarian neurotoxic phospholipase named A2-PLTX-Pcb1a for the first time. This phospholipase was isolated from the venomous extract of the zoanthid Palythoa caribaeorum. This enzyme, which is Ca²⁺-dependent, is a 149 amino acid residue protein. The analysis of the A2-PLTX-Pcb1a sequence showed neurotoxic domain similitude with other neurotoxic sPLA₂´s, but a different catalytic histidine domain. This is remarkable, since A2-PLTX-Pcb1a displays properties like those of other known PLA₂ enzymes. Full article

Palythoa caribaeorum (class Anthozoa) is a zoantharian which, together with other cnidarians, like jellyfishes, hydra, and sea anemones, possesses specialized structures in its tissues, the cnidocytes, which deliver an array of toxins in order to capture prey and deter predators. The whole transcriptome of P. caribaeroum was deep sequenced, and a diversity of toxin-related peptide sequences were identified, and some retrieved for functional analysis. In this work, a peptide precursor containing a ShK domain, named PcShK3, was analyzed by means of computational processing, comprising structural phylogenetic analysis, model prediction, and dynamics simulation of peptide-receptor interaction. The combined data indicated that PcShK3 is a distinct peptide which is homologous to a cluster of peptides belonging to the ShK toxin family. In vivo, PcShK3 distributed across the vitelline membrane and accumulated in the yolk sac stripe of zebrafish larvae. Notably, it displayed a significant cardio-protective effect in zebrafish in concentrations inferior to the IC₅₀ (<43.53 ± 6.45 µM), while in high concentrations (>IC₅₀), it accumulated in the blood and caused pericardial edema, being cardiotoxic to zebrafish larvae. Remarkably, PcShK3 suppressed the 6-OHDA-induced neurotoxicity on the locomotive behavior of zebrafish. The present results indicated that PcShK3 is a novel member of ShK toxin family, and has the intrinsic ability to induce neuro- and cardio-protective effects or cause cardiac toxicity, according to its effective concentration. Full article

Three new compounds, tuberazines A–C (1–3), and eleven known compounds (4–14) were obtained from the ethanolic extract of Taiwanese zoanthid Palythoa tuberculosa. Compounds 1–4 are rare marine natural products with a pyrazine moiety, and compound 5 is a tricyclic tryptamine derivative isolated from nature for the first time. The structures of all isolated metabolites were determined by analyzing their IR, Mass, NMR, and UV spectrometric data. The absolute configuration of 1 was confirmed by comparing the trend of experimental electronic circular dichroism (ECD) with calculated ECD spectra. The anti-lymphangiogenic activities of new compounds were evaluated in human lymphatic endothelial cells (LECs). Of these, new compound 3 displayed the most potent anti-lymphangiogenesis property by suppressing cell growth and tube formation of LECs. Full article

A new marine ecdysteroid with an α-hydroxy group attaching at C-4 instead of attaching at C-2 and C-3, named palythone A (1), together with eight known compounds (2–9) were obtained from the ethanolic extract of the Formosan zoanthid Palythoa mutuki. The structures of those compounds were mainly determined by NMR spectroscopic data analyses. The absolute configuration of 1 was further confirmed by comparing experimental and calculated circular dichroism (CD) spectra. Anti-dengue virus 2 activity and cytotoxicity of five isolated compounds were evaluated using virus infectious system and [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assays, respectively. As a result, peridinin (9) exhibited strong antiviral activity (IC₅₀ = 4.50 ± 0.46 μg/mL), which is better than that of the positive control, 2′CMC. It is the first carotene-like substance possessing anti-dengue virus activity. In addition, the structural diversity and bioactivity of the isolates were compared by using a ChemGPS–NP computational analysis. The ChemGPS–NP data suggested natural products with anti-dengue virus activity locate closely in the chemical space. Full article

The Zoanthids are an order of cnidarians whose venoms and toxins have been poorly studied. Palythoa caribaeorum is a zoanthid commonly found around the Mexican coastline. In this study, we tested the activity of P. caribaeorum venom on voltage-gated sodium channel (Na_V1.7), voltage-gated calcium channel (Ca_V2.2), the A-type transient outward (I_A) and delayed rectifier (I_DR) currents of K_V channels of the superior cervical ganglion (SCG) neurons of the rat. These results showed that the venom reversibly delays the inactivation process of voltage-gated sodium channels and inhibits voltage-gated calcium and potassium channels in this mammalian model. The compounds responsible for these effects seem to be low molecular weight peptides. Together, these results provide evidence for the potential use of zoanthids as a novel source of cnidarian toxins active on voltage-gated ion channels. Full article

One new hydroanthraquinone dimer with a rare C-9–C-7′ linkage, nigrodiquinone A (1), and four known anthraquinone monomers 2–5, were isolated from a fungus Nigrospora sp. obtained from the zoanthid Palythoa haddoni collected in the South China Sea. The structure of 1 was established through extensive NMR spectroscopy, and the absolute configuration was elucidated by comparing computed electronic circular dichroism (ECD) and optical rotations (OR) with experimental results. All the compounds were evaluated for antiviral activity, and 1 was also evaluated for antibacterial activity. Compound 4 displayed mild antiviral activity against coxsackie virus (Cox-B3) with the IC₅₀ value of 93.7 μM, and 5 showed an IC₅₀ value of 74.0 μM against respiratory syncytial virus (RSV). Full article