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Caribbean sea urchins are marine invertebrates that have experienced a decline over the years. Studies on sea urchins have focused primarily on the microbiome of the coelomic fluid or the gut microbiota. In this study, the epibiota community associated with four wild Caribbean sea urchin species, Lytechinus variegatus, Echinometra lucunter, Tripneustes ventricosus, and Diadema antillarum, was characterized for the first time. Using 57 sea urchin animal samples, we evaluated the influence of animal species, trophic niches, and geographical location on the composition of the epibiotic microbiota. We found significant differences in the bacterial biota among species and trophic niches, but not among geographical locations. L. variegatus exhibited the highest alpha diversity with high dominance of Fusobacteria, Planctomycetes, and Cyanobacteria, whereas T. ventricosus and D. antillarum were dominated by Firmicutes. T. ventricosus inhabiting the seagrass biotope dominated by Thalassia testudinum meadows had mostly Endozoicomonas. In contrast, samples located in the reef (dominated by corals and other reef builders) had a higher abundance of Kistimonas and Photobacterium. Our findings confirm that the epibiotic microbiota is species-specific, but also niche-dependent, revealing the trophic networks emerging from the organic matter being recycled in the seagrass and reef niches. As echinoids are important grazers of benthic communities, their microbiota will likely influence ecosystem processes. [ABSTRACT FROM AUTHOR]

Our goal was to understand the mechanisms behind the impact of nutrient enrichment at intermediate distances from aquaculture on the interactions of a subtidal macroalgae community with its main grazer, the sea urchin Paracentrotus lividus. We assessed the diversity and cover of the macroalgal community, the abundance and biometrics of the sea urchins, the carbon and nitrogen elemental and isotopic compositions, and their metabolome in two stations, at an intermediate distance (station A) and away (station B) from a fish cage facility in the Aegean Sea (Greece), during the warm and cold seasons. The nutrient input at station A favored a shift to a macroalgal assemblage dominated by turf-forming species, depleted of native-erected species and with a higher abundance of invasive algae. A stable isotope analysis showed fish-farm-associated nitrogen enrichment of the macroalgae and trophic transfer to P. lividus. A decrease in metabolites related to grazing, reproduction, and energy reserves was found in P. lividus at station A. Furthermore, the metabolomic analysis was able to pinpoint stress in P. lividus at an intermediate distance from aquaculture. The chosen combination of traditional ecology with omics technology could be used to uncover not only the sublethal effects of nutrient loading but also the pathways for species interactions. [ABSTRACT FROM AUTHOR]

The sea urchins Paracentrotus lividus and Arbacia lixula have a key role in benthic dynamics and they are often used to assess the toxicity of environmental contaminants. The aim of this research was to investigate the influence of salinity on copper toxicity on P. lividus and A. lixula embryos, evaluating the impact of future ocean salinity variations and estimating an optimum range for embryos. For this purpose, sea urchin embryos were exposed to different copper concentrations under varying salinity regimes, estimating the toxic effects with the percentage of abnormal embryos and the Integrative Toxicity Index (ITI). Results revealed acceptable levels of anomalies in a salinity range of 33–36‰ for A. lixula and 33–39‰ for P. lividus. The effect concentrations (EC50) of copper reveals increasing toxicity at increasing salinity for both sea urchin species, but between 33–36‰ (A. lixula) and 36–39‰ (P. lividus) the toxicity appear inversely related with salinity. This study illustrates the difficulty in relating a biological response to bioavailability, because the uptake and the sensitivity to copper across salinities is influenced by differences in osmoregulation, enhancing our knowledge about optimal salinity ranges and the potential impact of climate change on sea urchin embryo development. [ABSTRACT FROM AUTHOR]

Peptic ulcer is a widespread disease, with a lifetime frequency of 5–10% among the general population and an annual incidence of 0.1–0.3%. Ovothiol A is naturally produced from sea urchin eggs with special antioxidant activity. Gastric ulcers were induced in rats by a single ethanol dose (5 mL/kg). The rats were divided into control, ulcer, and ulcer with 250 and 500 mg/kg ovothiol A doses. Molecular docking studies were used to examine the interactions between ovothiol A and the H+/K+ ATPase active site residues. Ovothiol A led to a significant decline (p < 0.05) in gastric juice volume, ulcer index, MDA, IL-6, and cytochrome c, while levels of gastric juice pH, GSH, CAT, GST, SOD, and NO increased. Histopathological investigation of stomach sections revealed architecture preservation of the gastric mucosa after ovothiol A administration. The anti-ulcerogenic activity of ovothiol A includes scavenging free radicals, inhibition of inflammation, regulation of apoptosis, and stabilization of fibroblast growth factors to promote gastric ulcers healing. [ABSTRACT FROM AUTHOR]

Slow or nonexistent natural recovery of the Caribbean long-spined sea urchin (Diadema antillarum) following a mass mortality event in 1983–1984 has prompted interest in hatchery-origin production and restocking to aid coral-reef restoration. A critical first step is the ability to propagate D. antillarum from gametes, at scale. However, a unique larval biology and difficult and lengthy culture period of ~ 40 days has resulted in inconsistent success over the past 20-plus years. The purpose of this study was to develop protocols for rearing D. antillarum within a novel 1800-L recirculating aquaculture system capable of scaled production. Five separate experiments investigated larval development in response to diet quantity, diet composition, and initial stocking density within 40-L replicate culture tanks. The initial experiment was used to develop a microalgae reference diet consisting of Tisochrysis lutea and Chaetoceros sp. and revealed similar growth and survival between high quantity (40.0 × 103 cells mL−1) and low quantity (10.0 × 103 cells mL−1) treatments at 21 days post-fertilization (DPF). Experiments 2–4 examined diet quality by comparing carbon-equivalent microalgae compositions. Mixed diets containing Rhodomonas lens outperformed the reference diet in multiple experiments and a tripartite diet containing all three species resulted in significantly higher survival at 42 DPF. The highest growth overall occurred from a monoalgal R. lens diet, which indicated that this species is critically important. Further observations of density-dependent growth dynamics revealed that initial stocking densities > 1 larvae mL−1 significantly reduced growth over 28 DPF. Data generated were used to establish fundamental larviculture protocols that have since led to the production of over 1000 juveniles. [ABSTRACT FROM AUTHOR]

Fibrinogen-related proteins (FREPs) have been identified in several animals. They are involved in the body's defense, acting as mediators of phagocytosis. Ficolins and intelectins are some of the most studied Fibrinogen-related Domain (FReD)-containing lectins. In this work, we have isolated a singular FReD-containing lectin, which cannot be classified as ficolin or intelectin. ELL (Echinometra lucunter lectin) was isolated from coelomic plasma by affinity chromatography on xanthan gum. Primary structure was determined by tandem mass spectrometry. Moreover, antimicrobial activity of ELL was evaluated against planktonic cells and biofilm of Escherichia coli , Staphylococcus aureus and S. epidermidis. ELL showed hemagglutinating activity in Ca2+ presence, which was inhibited by glycoprotein mucin and thyroglobulin. Complete amino acid sequence consisted of 229 residues, including a FReD in the N-terminal. Searches for similarity found that ELL was very close to putative proteins from Strongylocentrotus purpuratus. ELL showed moderate similarity with uncharacterized sea stars proteins and protochordate intelectins. ELL was able to inhibit the planktonic growth of the Gram-positive bacteria and significantly reduce the biofilm formation of all bacteria tested. In conclusion, we identified a new type of FReP-containing lectin with some structural and functional conservation towards intelectins. • A Fibrinogen-related protein (FREP) was isolated from sea urchin Echinometra lcuunter. • ELL she is the first member of a new family of FREPs found in echinoderms. • ELL seems to be involved in the defense of the E. lucunter. • ELL was able to inhibit the planktonic growth of the Gram-positive bacteria. [ABSTRACT FROM AUTHOR]

The longspined sea urchin, Centrostephanus rodgersii, is a climate-driven pest species in south-eastern Australia. The harvest of this species is highly encouraged and in Tasmania, the existing fishery is expanding resulting in a large amount of waste that needs disposal. Research into use of waste products as inputs for organic or biodynamic farming systems can help reduce costs of disposal and keep the industry profitable; by sustaining or incrementing sea urchin harvest the industry can assist in their control. In the current study, urchin waste was dried and finely ground to a powder and applied to tomato plants in a greenhouse to examine the effect on growth and productivity. Urchin waste powder (UWP) had a mineral composition of Ca (40 g 100 g−1), Mg (1.7 g 100 g−1), P (0.03 g 100 g−1), Fe (19.34 mg kg−1) and B (38 mg kg−1), a pH 8.06 in water and an Electrical Conductivity (EC) value of 7.64 dSm−1. Seven different treatment rates of UWP (0.3%; 0.5%; 0.8%; 1%; 2%; 3%; 5%), were added to 10 replicate pots containing 4 kg nutrient-poor potting mix planted with tomato (Variety K1) seedlings. Plant growth, yield, quality attributes and mineral content of tomato were measured under UWP treatments with comparison against a Hoagland solution control. UWP influenced tomato growth and productivity proportional to the quantity applied, however, the Hoagland solution control had a significantly greater yield. Potting mix pH increased from 6.8 to 7 and higher available P was detected in potting mix receiving higher rates of UWP. No phytotoxic effects were detected. The highest UWP treatment matched the Hoagland control in fruit quality and nutritional composition. Processing waste from the sea urchin fishery has potential as organic fertiliser or amendment providing plant-available Ca and some microelements such as Boron. [ABSTRACT FROM AUTHOR]

The sea urchin, Diadema setosum, is a poisonous species that originates in the Indo‐Pacific and the Red Sea. Although this species has been recorded in several areas in the Mediterranean Sea, its habitat selection, density, distribution and ecological impacts have not been comprehensively documented to date. This study combined the diving observations (n = 53 sites) and local ecological knowledge (LEK) of SCUBA divers (n = 100) to provide information on the distribution and density of this invasive sea urchin on the Aegean and Levantine coasts of Turkey between September and October 2020. The results indicated that D. setosum was more prevalent along the southern coast of Turkey compared with the western coast, where it is colder. The highest densities of D. setosum were observed in rocky habitats at a depth range of 0–5 m. Moreover, the densities increased with increasing bottom temperatures (up to 150 ind./100 m2). Recent reports from the Levantine and south Aegean coasts highlighted that the densities of D. setosum increased dramatically during the past year. The results of the present study suggested that D. setosum provides shelter for a total of four fish species, including Chromis chromis, Gobius sp., Cheilodipterus novemstriatus and Thalassoma pavo. This species of urchin poses a threat due to its potential grazing and bioerosion effects in the Mediterranean. Thus, future studies should focus on the feeding ecology of D. setosum and the competition with native species that share the same habitat to obtain an improved understanding of the ecological impacts of this invasive species. Although the present study provides the first comprehensive dataset on the density and distribution of this invasive sea urchin for Turkey in the eastern Mediterranean region, we suggest that its population should be monitored for long periods using direct observations, LEK and citizen science. [ABSTRACT FROM AUTHOR]

Diclofenac (DCF), a non-steroidal anti-inflammatory drug (NSAID), is among the main pollutants of aquatic environments. Nevertheless, even if several authors evaluated its effects on marine organisms, no work has ever analysed its impact on the sea urchin Arbacia lixula. The purpose of this study was to analyse, for the first time, the impact of DCF at different concentrations (50 mg/l, 5 mg/l, 0.5 mg/l, 0.05 mg/l) on A. lixula embryos and gametes to indicate possible safe minimum levels of release of this drug in marine environments. Our results showed significant concentration-dependent effects on embryonic development (decrease in the number of developed embryos and increase in the quantity of degenerated eggs) and significant levels of bioaccumulation at DCF concentrations of 50 mg/l in both gametes and embryos. DCF showed a significant impact on the fertilisation of A. lixula due to its effects on gametes, confirming the possibility of environmental risk and highlighting the need to improve wastewater treatment and drug disposal processes. [ABSTRACT FROM AUTHOR]

Aotearoa New Zealand is the last major landmass settled by people, and therefore provides a recent record of ecological legacy effects in the coastal zone. Large‐scale land clearances of forests accelerated over the last century, affecting the concentration of suspended sediments, light environment, and nutrient composition on rocky reefs, and consequently the distribution, abundance, and composition of algal forests. The environmental effects were compounded in many places by overfishing and long‐term declines of large predatory species, often leading to proliferation and extensive grazing by sea urchins. In this study, we examine these processes in three biogeographic regions that have been differentially affected by ecological legacy effects. The study was based on the depth‐specific associations between sea urchins (Evechinus chloroticus) and the common kelp (Ecklonia radiata) from multiple sites within each region, some of which were sampled over two decades within no‐take marine reserves and in actively fished areas. Satellite‐derived estimates of water‐column properties were used as proxies for the relative effects of coastal sedimentation on kelp forest habitats. We then used an information‐theoretic framework to assess the relative factor weightings of marine reserve effects on urchin density, total suspended solids (TSS), and regional urchin density on the depth‐specific density of Ecklonia radiata. The fishing effects were significant within and outside of reserves in the northern and central regions, but the effect sizes were by far strongest in the northern region. In the central region characterized by extensive land clearance and forestry combined with high coastal retention of water, the concentration of TSS had a major influence on the depth distribution of kelp, confining it to shallow water (<10‐m depth) in small patches where urchins did not overgraze. These patterns are in sharp contrast to the small marine reserve effects and deep distribution of Ecklonia radiata in the southern region, which has intact native forested catchments, comparatively low fishing pressure, and a large regional network of marine reserves. The results highlight important differences in how centuries‐old legacies of land clearance and exploitation affect regional‐scale dynamics of sea urchins and kelp and define the appropriate spatial scale of ecosystem‐based management of critical kelp forest habitats. [ABSTRACT FROM AUTHOR]

Kelp deforestation by sea urchin grazing is a widespread phenomenon globally, with vast consequences for coastal ecosystems. The ability of sea urchins to survive on a kelp diet of poor nutritional quality is not well understood and bacterial communities in the sea urchin intestine may play an important role in digestion. A no-choice feeding experiment was conducted with the sea urchin Strongylocentrotus droebachiensis, offering three different seaweeds as diet, including the kelp Saccharina latissima. Starved sea urchins served as experimental control. Amplicons of the 16S rRNA gene were analyzed from fecal pellets. One dominant symbiont (Psychromonas marina) accounted for 44% of all sequence reads and was especially abundant in the sea urchins fed seaweed diets. The starved and field captured sea urchins consistently displayed higher diversity than the seaweed-fed sea urchins. Cloning and sequencing of the nifH gene revealed diverse nitrogen fixers. We demonstrate that the sea urchin intestinal microbiome is dynamic, with bacterial communities that are plastic depending on diet and have the capacity for nitrogen fixation. This reflects the dietary flexibility of these sea urchins, and their intestinal microbiota could be a key component in understanding catastrophic kelp forest grazing events., (© The Author(s) 2025. Published by Oxford University Press on behalf of FEMS.)

The regulation of mitotic spindle position and orientation, and consequent division plane specification, is critical for early embryo development, tissue architecture and stem cells. Accordingly, defects in spindle positioning have been associated with the emergence of tissue disorders and mis-specification of cell fates, causing the formation of tumors, for instance, in stem cell populations. In such context, methods to physically manipulate mitotic spindle position or orientation in living cells bear the promise of dissecting the causal impact of spindle mis-positioning on cell or tissue behavior. Here, we describe a method to directly modulate mitotic spindle position and orientation with in vivo magnetic tweezers in developing sea urchin embryos. This method allows for monitoring the impact of spindle orientation on embryo development and quantifying forces and torques needed to move or rotate spindles. It may be transposable to many other cell, embryo or tissue types., (© 2025. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Abstract There is a growing interest in sea urchin roe enhancement around the world, but relatively little is known about the physical differences between enhanced and wild sea urchin roe and the causes of any differences. The main objective of this study was to compare various aspects of roe from wild and enhanced green sea urchin (Strongylocentrotus droebachiensis) using morphological and histological examinations, as well as analyses of amino and fatty acids, and gene expression profiles. Sea urchins were collected (n = 250) from a wild population and held in raceways where they were fed a commercially available formulated diet for 14 weeks (mid‐August – mid‐November). At consecutive time‐points, samples from the wild and enhanced sea urchins were obtained. The gonad index (GI) increased significantly in the enhanced sea urchins from 6.1% to 29.65% at week 12, while no significant increase was recorded in wild sea urchins. The concentrations of the amino acids' glycine, lysine and leucine were different between the treatments, the first two being higher and the latter lower in the enhanced sea urchin roe. Wild sea urchins had 6% more unidentified fatty acid content than enhanced sea urchins. A significant progress in reproductive stages in wild sea urchins was observed; however, none in the enhanced sea urchins, suggesting gametogenesis is inhibited in captivity, or variations in feed availability. Enhanced sea urchins had relatively less reproductive cells and an overall messier and less uniform appearance mid‐trial (weeks 8–10). Scanning electron microscopy images showed less structured and greater number of surface flagella in enhanced sea urchins. Transcriptomic analysis by RNA‐sequencing showed a total of 255 differentially expressed genes between the wild and enhanced groups, which had functions largely involved in the biosynthesis of cholesterol and fatty acids, and ethanol degradation.

Spermiotoxic, embryotoxic and cytotoxic effects of the widely used biofouling biocide copper pyrithione (CuPt) were evaluated in bioassays to examine the inhibition of fertilization rate, offspring quality and effects on early development of the sea urchin Paracentrotus lividus. CuPt was non-spermiotoxic for fertilization rates but the frequency of embryonic malformations increased in a concentration-dependent manner when eggs were fertilized with CuPt-exposed sperm. CuPt EC 50 was calculated to be 13.58 µg/l for embryotoxicity. While the frequency of normally developed plutei decreased, the number of larvae with skeletal deformations increased. The IC 25 and IC 50 values in cytotoxicity assays were calculated to be 12.79 and 47.85 µg/l, respectively. The study revealed statistically significant decrease in the number of mitotically dividing cells, increase in the percentage of interphase cells and increased chromosomal abnormalities in the exposed cells. According to these results, CuPt can be said to have a highly toxic effect on sea urchin embryos at the applied concentrations. This situation suggests that there may be a potential risk of marine contamination with CuPt for this species.

Climate change is impacting marine ecosystem community dynamics on a global scale. While many have assessed direct effects of climate change, indirect effects on marine ecosystems produced by biotic interactions remain poorly understood. For example, warming-induced range expansions and increased consumption rates of herbivores can lead to significant and unexpected changes in seagrass-dominated ecosystems. To better understand the threats tropicalization presents for the functioning of turtlegrass (Thalassia testudinum) meadows, we focused on the extensive turtlegrass beds of St. Joseph Bay, Florida in the northern Gulf of Mexico, a location with increasing numbers of tropically-associated green turtles. Our goals were to investigate experimentally how different grazing rates (natural and simulated),including high levels reflective of green turtle herbivory, coupled with nutrient supply, might alter turtlegrass structure and functioning in a higher latitude, subtropical turtlegrass meadow. We found that 4 months of varying levels of herbivory did not affect turtlegrass productivity, while 7 months of herbivory reduced percent cover, and 10 months reduced shoot density. Nutrient additions had few important effects. Ten months into the study, a massive recruitment of the herbivorous sea urchin (Lytechinus variegatus), whose densities reached 19 urchins/m2 completely overgrazed our study area and a large portion of the lush turtlegrass meadows of St. Joseph Bay. While local turtlegrass overgrazing had been previously noted at these urchin densities, a total loss of seagrass in such a large area has rarely ever been recorded. Overgrazing of the kind we observed, likely a result of both urchin and increasing green turtle grazing, can result in the loss of many key ecosystem services. As tropicalization continues, understanding how changes in biotic interactions, such as increased herbivory, affect higher latitude seagrass meadows will be necessary for their proper management and conservation.

The consequences of using 25% whole or shelled sea urchin as an ingredient in anchovy sauce on its fermentation and development of its physicochemical properties after 20 days fermentation was studied. Two varieties of fish and sea urchin sauce were made with or without shell at 1:2:1 ratio (salt:fish:sea urchin) plus a control fish sauce at 1:3 ratio (salt:fish). All sauces were fermented at 40–50 °C for 20 days, where for the first 7 days the preparation remained in a static phase. During their fermentation, pH, salt concentration, aw, TVB-N, TMA, total nitrogen, formaldehyde nitrogen, amino nitrogen, and ammonium nitrogen, as well as aerobic mesophiles and lactic acid bacteria were monitored. The fermentation of the experimental sauces proved to follow an evolution rather similar to the control sauce. The whole and shelled sea urchins provided the necessary microbial and enzymatic load to trigger an adequate hydrolysis of the fish and the production of total nitrogen (16.0–17.6 g/L), formaldehyde nitrogen (15.1–16.0 g/L), and amino nitrogen (0.7–0.8 g/L) of the same order as the control sauce, despite the lower fish content. According to TMA (9.2–13.1 mg N/100 g), VBT (40.0–47.2 mg N/100 g) contents, and pH levels (5.41–5.46), no deviation of the fermentation process was observed under the experimental conditions (salt content, temperature, and agitation after the static phase). Quantitative descriptive analysis (QDA) sensory revealed that the use of sea urchin results in high quality products characterized by their aromas of crustaceans and mollusks. The present study investigates the potential use of shelled and even whole sea urchin as an ingredient for the preparation of high quality fish sauces.

Coping with a zero-waste, more sustainable economy represents the biggest challenge for food market nowadays. We have previously demonstrated that by applying smart multidisciplinary waste management strategies to purple sea urchin (Paracentrotus lividus) food waste, it is possible to obtain both a high biocompatible collagen to produce novel skin substitutes and potent antioxidant pigments, namely polyhydroxynapthoquinones (PHNQs). Herein, we have analyzed the biological activities of the PHNQs extract, composed of Spinochrome A and B, on human skin fibroblast cells to explore their future applicability in the treatment of non-healing skin wounds with the objective of overcoming the excessive oxidative stress that hinders wound tissue regeneration. Our results clearly demonstrate that the antioxidant activity of PHNQs is not restricted to their ability to scavenge reactive oxygen species; rather, it can be traced back to an upregulating effect on the expression of superoxide dismutase 1, one of the major components of the endogenous antioxidant enzymes defense system. In addition, the PHNQs extract, in combination with Antimycin A, displayed a synergistic pro-apoptotic effect, envisaging its possible employment against chemoresistance in cancer treatments. Overall, this study highlights the validity of a zero-waste approach in the seafood chain to obtain high-value products, which, in turn, may be exploited for different biomedical applications.

Background: The assessment of oocyte quality is, nowadays, a major challenge in aquaculture, oocyte cryopreservation, and environmental science. Oocyte quality is a determining factor in fertilization and embryo development; however, there is still a lack of rapid and sensitive cellular markers for its assessment. Currently, its estimation is predominantly based on morphological analysis, which is subjective and does not consistently reflect the developmental competence of the oocytes. Despite several recent studies investigating molecular markers related to oocyte quality, methods currently available for their determination pose various technical challenges and limitations. In this study, we developed a novel approach based on fluorescence spectroscopy to assess different intrinsic physiological parameters that can be employed to evaluate egg quality in marine invertebrates that are widely used as animal models such as sea urchins and mussels. Results: Different physiological parameters, such as viability, mitochondrial activity, intracellular ROS levels, plasma membrane lipid peroxidation, and intracellular pH, for egg quality evaluation have been successfully assessed in sea urchins and mussels by using specific fluorescent dyes and detecting the fluorescent signals in eggs through fluorescence spectroscopy. Conclusions: Based on our findings, we propose these physiological markers as useful predictors of egg quality in marine invertebrates; they can be estimated rapidly, selectively, and sensitively by employing this novel approach, which, due to the speed of analysis, the low cost, and easy use can be considered a powerful analytical tool for the egg quality assessment. [ABSTRACT FROM AUTHOR]

Aim: In the context of intensifying threats of climate change on marine communities, ecological models are widely applied for conservation strategies, though polar studies remain scarce given the limited number of datasets available. Correlative (e.g. species distribution models, SDM) and mechanistic (e.g. dynamic energy budget models, DEB) modelling approaches are usually used independently in studies. Using both approaches in integrative, hybrid models could help to better estimate the species potential ecological niche, as mechanistic and correlative models complement each other very well, giving more insights into species potential response to fast‐changing environmental conditions. Location: The study focusses on the Baie du Morbihan, a silled basin located in the east of the Kerguelen Islands (sub‐Antarctic). Methods: A hybrid, correlative‐mechanistic model was implemented to predict the response of the endemic sea urchin Abatus cordatus (Verrill, 1876). We compared the performances of classic and integrated approaches to predict A. cordatus distribution according to two dates representing seasonal contrasts. Two integrated approaches were studied and performed by either (1) including the spatial projection of the DEB model as an input layer inside the SDM ('integrated SDM‐DEB') or (2) using a Bayesian procedure to use DEB model outputs as priors of the SDM ('integrated Bayesian' approach). Results: Results show higher performances of 'integrated Bayesian' approaches to evaluate A. cordatus potential ecological niche compared with 'classic' and 'integrated SDM‐DEB' methods. The influence of environmental conditions on model predictions is further captured with these Bayesian procedures and better highlights the environmental influence on the species‐predicted distribution. Model performance is good for the different simulations, and uncertainty in predictions is well‐highlighted. Main conclusions: The good performances of 'integrated Bayesian' approaches to estimate species potential ecological niche opens perspectives for future applications to a broad panel of natural examples, noteworthy for decision‐making and conservation management purposes. [ABSTRACT FROM AUTHOR]

Rapid industrialization in the State of Kuwait caused unprecedented pollution in the marine environment over the recent years. Studies on the effect of mercury (Hg) was least evidenced when compared to other trace metals in Echinometra mathaei, sea urchin collected from the Al-Fintas (Site-A) and Mina Abduallah (Site-B), Southern Kuwait. Reasons were attributed to (a) seasonal restriction of sea urchin abundance, (b) their low mercury concentrations in the Coastal waters (c) analytical imperfection and sensitivity of the instrumentation. In this study, the instrumental lacunae were overcome by using direct mercury analyzer (DMA-80, Milestone, Italy) which yielded consistent and reproducible Hg concentrations in all the samples. In nature, high Hg concentrations were observed in the seawater at 23 °C > 15 °C > 12 °C irrespective of the sites although the total mean Hg concentration was high in Site-A over Site-B. The 96 h and 180 d exposed E. mathaei to LC50 toxicity, and bioaccumulation tests revealed high Hg concentrations in E. mathaei in relation to differential temperature in the sequence of 15 °C > 23 °C > 12 °C with minimal fluctuation of the hydrological parameters. Season-wise analysis showed high Hg concentrations in both the seawater and sea urchin body parts during the winter seasons compared to the summer season and irrespective of the two sites. Thus, this study recommends possible Hg mitigation that affects the socioeconomic condition of the marine resources besides, labeling the sea urchin as a bio-monitoring tool to Hg pollution. [ABSTRACT FROM AUTHOR]

The SpTransformer (SpTrf) gene family encodes a set of proteins that function in the sea urchin immune system. The gene sequences have a series of internal repeats in a mosaic pattern that is characteristic of this family. This mosaic pattern necessitates the insertion of large gaps, which has made alignments of the deduced protein sequences computationally difficult such that only manual alignments have been reported previously. Because manual alignments are time consuming for evaluating newly available SpTrf sequences, computational approaches were evaluated for the sequences reported previously. Furthermore, because two different manual alignments of the SpTrf sequences are feasible because of the multiple internal repeats, it is not known whether additional alternative alignments can be identified using different approaches. The bioinformatic program, PRANK, was used because it was designed to align sequences with large gaps and indels. The results from PRANK show that the alignments of the internal repeats are similar to those done manually, suggesting multiple feasible alignments for some regions. GUIDANCE based analysis of the alignments identified regions that were excellent and other regions that failed to align. This suggests that computational approaches have limits for aligning the SpTrf sequences that include multiple repeats and that require inserted gaps. Furthermore, it is unlikely that alternative alignments for the full-length SpTrf sequences will be identified. [ABSTRACT FROM AUTHOR]

The roe enhancement of sea urchins from barrens requires suitable transport techniques to enable transport of live sea urchins to enhancement facilities. For the green sea urchin Strongylocentrotus droebachiensis, the maximum period that the 'out of water' techniques described in this manuscript could be used is temperature dependent. When transported at 3.0°C, this should be no longer than 44‐hours, 36‐hours at 5.0°C and 14‐hours at an average temperature of 14.3°C. The survival results from the 'in water' transport system described in this manuscript indicate that this type of transport method will be suitable for transporting sea urchins for periods up to 22‐days and possibly longer if ammonia‐stripping (denitrifying) capacity is included in the transport system. The results of the post transport enhancement trial show that it is feasible to hold sea urchins at the densities tested for periods up to 14‐days and then to re‐immerse them in seawater holding systems and enhance the roe of the sea urchins successfully. There was a significant increase in gonad index in the sea urchins held in all the transport treatments compared to the initial wild GI, except in the sea urchins held at high density for 7 days. However, higher mortalities occurred in all transported sea urchins, and these were higher in sea urchins held at higher densities and for longer periods. The authors recommend the development of stress and welfare indicators for captive sea urchins to enable the 'fitness' of sea urchins during transport and captivity. [ABSTRACT FROM AUTHOR]

With rising ocean temperatures, extreme weather events such as marine heatwaves (MHWs) are increasing in frequency and duration, pushing marine life beyond their physiological limits. The potential to respond to extreme conditions through physiological acclimatization, and pass on resistance to the next generation, fundamentally depends on the capacity of an organism to cope within their thermal tolerance limits. To elucidate whether heat conditioning of parents could benefit offspring development, we exposed adult sea urchins (Heliocidaris erythrogramma) to ambient summer (23°C), moderate (25°C) or strong (26°C) MHW conditions for 10 days. Offspring were then reared at constant temperature along a thermal gradient (22–28°C) and development was tracked to the 14‐day juvenile stage. Progeny from the MHW‐conditioned adults developed through to metamorphosis faster than those of ambient conditioned parents, with most individuals from the moderate and strong heatwaves developing to the larval stage across all temperatures. In contrast, the majority of offspring from the control summer temperature died before metamorphosis at temperatures above 25°C (moderate MHW). Juveniles produced from the strong MHW‐conditioned adults were also larger across all temperatures, with the largest juveniles in the 26°C treatment. In contrast, the smallest juveniles were from control (current‐day summer) parents (and reared at 22 and 25°C). Surprisingly, initial survival was higher in the progeny of MHW exposed parents, even at temperatures hotter than predicted MHWs (28°C). Importantly, however, there was substantial mortality of juveniles from the strong MHW parents by day 14. Therefore, while carryover effects of parental conditioning to MHWs resulted in faster growing, larger progeny, this benefit will only persist beyond the more sensitive juvenile stage and enhance survival if conditions return promptly to normal seasonal temperatures within current thermal tolerance limits. [ABSTRACT FROM AUTHOR]

Simple Summary: Cell division, also known as mitosis, relies on a complex cascade of molecular events that orchestrates the whole process and decides when cells can start dividing. A key factor in this process is protein synthesis, which is carefully regulated inside the cell to assure the timely production of all the proteins required for mitosis. The embryos of sea urchins divide rapidly after fertilization and represent an informative model to analyze the role of protein synthesis regulation during cell cycle progression. For example, the analysis in the 1980s of sea urchin embryos fostered the discovery of Cyclin B, the first representative of a family of proteins that plays a universal role in controlling cell division. This finding was awarded in 2001 with the Nobel Prize in Physiology and Medicine. However, much remains to be learned, and how protein synthesis controls the time and speed of mitosis in a developing embryo is still unclear. For instance, discovering whether the translation of other mRNAs than mitotic cyclins is required to finely regulate the rate of embryonic cleavage has never been tested. In this work, we investigated the role of the translation of an mRNA encoding a protein called eIF4B in the dynamics of embryonic cell division. We showed that newly synthesized eIF4B directly impacts cell division rates in two sea urchin species. Cell divisions are delayed when the production of eIF4B is inhibited in a fertilized egg. Conversely, increased production of eIF4B accelerates mitosis. Therefore, eIF4B mRNA translation represents a new means to regulate the pace of embryonic cleavages. Moreover, since eIF4B is a translational regulator, our findings suggest that the function of its mRNA translation is boosting the production of other proteins essential for mitosis. The cells of the sea urchin embryos seem thus equipped with a controlling device capable of modulating cell division rates, a molecular switch that could contribute to coordinating the first steps of development in other animals as well. During the first steps of sea urchin development, fertilization elicits a marked increase in protein synthesis essential for subsequent cell divisions. While the translation of mitotic cyclin mRNAs is crucial, we hypothesized that additional mRNAs must be translated to finely regulate the onset into mitosis. One of the maternal mRNAs recruited onto active polysomes at this stage codes for the initiation factor eIF4B. Here, we show that the sea urchin eIF4B orthologs present the four specific domains essential for eIF4B function and that Paracentrotus lividus eIF4B copurifies with eIF4E in a heterologous system. In addition, we investigated the role of eIF4B mRNA de novo translation during the two first embryonic divisions of two species, P. lividus and Sphaerechinus granularis. Our results show that injection of a morpholino directed against eIF4B mRNA results in a downregulation of translational activity and delays cell division in these two echinoids. Conversely, injection of an mRNA encoding for P. lividus eIF4B stimulates translation and significantly accelerates cleavage rates. Taken together, our findings suggest that eIF4B mRNA de novo translation participates in a conserved regulatory loop that contributes to orchestrating protein synthesis and modulates cell division rhythm during early sea urchin development. [ABSTRACT FROM AUTHOR]

Echinometra is the most widespread genus of sea urchin and has been the focus of a wide range of studies in ecology, speciation, and reproduction. However, available genetic data for this genus are generally limited to a few select loci. Here, we present a chromosome-level genome assembly based on 10x Genomics, PacBio, and Hi-C sequencing for Echinometra sp. EZ from the Persian/Arabian Gulf. The genome is assembled into 210 scaffolds totaling 817.8 Mb with an N50 of 39.5 Mb. From this assembly, we determined that the E. sp. EZ genome consists of 2 n  = 42 chromosomes. BUSCO analysis showed that 95.3% of BUSCO genes were complete. Ab initio and transcript-informed gene modeling and annotation identified 29,405 genes, including a conserved Hox cluster. E. sp. EZ can be found in high-temperature and high-salinity environments, and we therefore compared E. sp. EZ gene families and transcription factors associated with environmental stress response ("defensome") with other echinoid species with similar high-quality genomic resources. While the number of defensome genes was broadly similar for all species, we identified strong signatures of positive selection in E. sp. EZ noncoding elements near genes involved in environmental response pathways as well as losses of transcription factors important for environmental response. These data provide key insights into the biology of E. sp. EZ as well as the diversification of Echinometra more widely and will serve as a useful tool for the community to explore questions in this taxonomic group and beyond. [ABSTRACT FROM AUTHOR]

The impact of new technology can be appreciated by how broadly it is used. Investigators that previously relied only on pharmacological approaches or the use of morpholino antisense oligonucleotide (MASO) technologies are now able to apply CRISPR-Cas9 to study biological problems in their model organism of choice much more effectively. The transitions to new CRISPR-based approaches could be enhanced, first, by standardized protocols and education in their applications. Here we summarize our results for optimizing the CRISPR-Cas9 technology in a sea urchin and a sea star, and provide advice on how to set up CRISPR-Cas9 experiments and interpret the results in echinoderms. Our goal through these protocols and sharing examples of success by other labs is to lower the activation barrier so that more laboratories can apply CRISPR-Cas9 technologies in these important animals. [Display omitted] • CRISPR-based approaches need standardized protocols for each animal. • Here we optimize the Cas9 technology in a sea urchin and a sea star. • We give advice on experimental set up and interpretation of the results. • Our goal is to enhance use of CRISPR-Cas9 technologies in these important animals. [ABSTRACT FROM AUTHOR]

Background: Irregular echinoids are ecosystem engineers with diverse functional services. Documenting present-day distribution of those widespread organisms is important for understanding their ecological significance and enhancing our ability to interpret their rich fossil record. Methods: This study summarizes SCUBA surveys of clypeasteroid and spatangoid echinoids conducted in 2020 and 2021 along the central part of the Florida Keys. The survey included observations on both live and dead specimens, their distribution, habitat preferences, abundance, and live-dead comparison. Results: Echinoids were found at 17 out of 27 examined sites (63%) and occurred across a wide range of habitats including coastal seagrass meadows, subtidal sand and seagrass settings of the Hawk Channel, backreef sands, and fine muddy sands of deeper forereef habitats. The encountered species, both dead and alive, included Clypeaster rosaceus (four sites), Clypeaster subdepressus (five sites), Encope michelini (three sites), Leodia sexiesperforata (eight sites), Meoma ventricosa (nine sites), and Plagiobrissus grandis (four sites). All sites were dominated by one species, but some sites included up to five echinoid species. Live-dead fidelity was high, including a good agreement in species composition of living and dead assemblages, congruence in species rank abundance, and overlapping spatial distribution patterns. This high fidelity may either reflect long-term persistence of local echinoid populations or fragility of echinoid tests that could prevent post-mortem transport and the formation of time-averaged death assemblages. Regardless of causative factors, the live-dead comparisons suggest that irregular echinoid assemblages, from settings that are comparable to the study area, may provide a fossil record with a high spatial and compositional fidelity. The survey of live fauna is consistent with past regional surveys in terms of identity of observed species, their rank abundance, and their spatial distribution patterns. The results suggest that despite increasingly frequent hurricanes, active seasonal fisheries, massive tourism, and urban development, irregular echinoids continue to thrive across a wide range of habitats where they provide diverse ecosystem services by oxygenating sediments, recycling organic matter, supporting commensal organisms, and providing food to predators. Results reported here document the present-day status of local echinoid populations and should serve as a useful reference point for assessing future regional changes in echinoid distribution and abundance. [ABSTRACT FROM AUTHOR]

Myocardial infarction (MI) is one of the most prevalent disorders seen in clinical practice, and its prevalence has risen dramatically in the last decade. Ovothiol‐A is a natural product isolated from sea urchin eggs and display unusual antioxidant properties. The present study investigates the therapeutic effect of Ovothiol‐A against MI stimulated in rats by epinephrine injection. Subcutaneous injection of 2 mg/kg epinephrine for 2 days caused MI in rats. The rats divided into three groups; control, MI, and MI treated with Ovothiol‐A (500 mg/kg, orally) for 7 days. The treatment with Ovothiol‐A restored ST‐segment near normal, ameliorated the changes in cardiac troponin T, creatine kinase, lactate dehydrogenase, aspartate aminotransferase, alanine amino transferase, alkaline phosphatase, total proteins, creatinine, uric acid, urea, malondialdehyde, nitric oxide, reduced glutathione, catalase, glutathione‐S‐transferase, hemoglobin, RBCs, WBCs, platelet/lymphocyte ratio, and neutrophil/lymphocyte ratio. The histological investigation revealed that Ovothiol‐A‐treated group showed marked improvement in the examined cardiac muscles, liver and kidney in numerous sections. Ovothiol‐A possessed a therapeutic effect against epinephrine‐induced myocardial infarction. Ovothiol‐A improves cardiac, liver, and kidney biomarkers and restores the typical pattern of EEG. Practical applications: Eggs of sea urchins are rich in potent antioxidant molecule (Ovothiol‐A).The current study reveals the ability to use Ovothiol‐A in the treatment of myocardial infarction. [ABSTRACT FROM AUTHOR]

Molecular research on the evolution of extraocular photoreception has drawn attention to photosensitive animals lacking proper eye organs. Outside of vertebrates, little is known about this type of sensory system in any other deuterostome. In this study, we investigate such an extraocular photoreceptor cell (PRC) system in developmental stages of the sea urchin Paracentrotus lividus. We provide a general overview of the cell type families present at the mature rudiment stage using single-cell transcriptomics, while emphasizing the PRCs complexity. We show that three neuronal and one muscle-like PRC type families express retinal genes prior to metamorphosis. Two of the three neuronal PRC type families express a rhabdomeric opsin as well as an echinoderm-specific opsin (echinopsin), and their genetic wiring includes sea urchin orthologs of key retinal genes such as hlf, pp2ab56e, barh, otx, ac/sc, brn3, six1/2, pax6, six3, neuroD, irxA, isl and ato. Using qPCR, in situ hybridization, and immunohistochemical analysis, we found that the expressed retinal gene composition becomes more complex from mature rudiment to juvenile stage. The majority of retinal genes are expressed dominantly in the animals' podia, and in addition to the genes already expressed in the mature rudiment, the juvenile podia express a ciliary opsin, another echinopsin, and two Go-opsins. The expression of a core of vertebrate retinal gene orthologs indicates that sea urchins have an evolutionarily conserved gene regulatory toolkit that controls photoreceptor specification and function, and that their podia are photosensory organs. [ABSTRACT FROM AUTHOR]

Echinoderms are an acknowledged source of bioactive compounds exerting various beneficial effects on human health. Here, we examined the potential in vitro anti-hepatocarcinoma effects of aqueous extracts of the cell-free coelomic fluid obtained from the sea urchin Arbacia lixula using the HepG2 cell line as a model system. This was accomplished by employing a combination of colorimetric, microscopic and flow cytometric assays to determine cell viability, cell cycle distribution, the possible onset of apoptosis, the accumulation rate of acidic vesicular organelles, mitochondrial polarization, cell redox state and cell locomotory ability. The obtained data show that exposed HepG2 cells underwent inhibition of cell viability with impairment of cell cycle progress coupled to the onset of apoptotic death, the induction of mitochondrial depolarization, the inhibition of reactive oxygen species production and acidic vesicular organelle accumulation, and the block of cell motile attitude. We also performed a proteomic analysis of the coelomic fluid extract identifying a number of proteins that are plausibly responsible for anti-cancer effects. Therefore, the anti-hepatocarcinoma potentiality of A. lixula's preparation can be taken into consideration for further studies aimed at the characterization of the molecular mechanism of cytotoxicity and the development of novel prevention and/or treatment agents. [ABSTRACT FROM AUTHOR]

For hundreds of years, biologists have studied accessible organisms such as garden peas, sea urchins collected at low tide, newt eggs, and flies circling rotten fruit. These organisms help us to understand the world around us, attracting and inspiring each new generation of biologists with the promise of mystery and discovery. Time and time again, what we learn from such simple organisms has emphasized our common biological origins by proving to be applicable to more complex organisms, including humans. Yet, biologists are increasingly being tasked with developing applications from the known, rather than being allowed to follow a path to discovery of the as yet unknown. Here, we provide examples of important lessons learned from research using selected non-vertebrate organisms. We argue that, for the purpose of understanding human disease, simple organisms cannot and should not be replaced solely by human cell-based culture systems. Rather, these organisms serve as powerful discovery tools for new knowledge that could subsequently be tested for conservation in human cell-based culture systems. In this way, curiosity-driven biological research in simple organisms has and will continue to pay huge dividends in both the short and long run for improving the human condition.

Cilia are organelles specialized for movement and signaling. To infer when during evolution signaling pathways became associated with cilia, we characterized the proteomes of cilia from sea urchins, sea anemones, and choanoflagellates. We identified 437 high-confidence ciliary candidate proteins conserved in mammals and discovered that Hedgehog and G-protein-coupled receptor pathways were linked to cilia before the origin of bilateria and transient receptor potential (TRP) channels before the origin of animals. We demonstrated that candidates not previously implicated in ciliary biology localized to cilia and further investigated ENKUR, a TRP channel-interacting protein identified in the cilia of all three organisms. ENKUR localizes to motile cilia and is required for patterning the left-right axis in vertebrates. Moreover, mutation of ENKUR causes situs inversus in humans. Thus, proteomic profiling of cilia from diverse eukaryotes defines a conserved ciliary proteome, reveals ancient connections to signaling, and uncovers a ciliary protein that underlies development and human disease.

Marine larvae have factored heavily in pursuits to understand the origin and evolution of animal life cycles. Recent comparisons of gene expression and chromatin state in different species of sea urchin and annelid show how evolutionary changes in embryonic gene regulation can lead to markedly different larval forms. [ABSTRACT FROM AUTHOR]

Stocking hatchery propagated long-spined sea urchins Diadema antillarum is a priority option for recovery of this keystone herbivore on Caribbean reefs. However, information on captive culture of D. antillarum is very limited due to historical lack of successful juvenile production from gametes in the hatchery. In this study, hatchery propagated D. antillarum juveniles were cultured using two diets, commercially available herbivore pellets and dried nori, with the presence/absence of stony coral Acropora cervicornis skeleton to understand how diet and habitat complexity affect growth and behavior of juveniles. Juvenile urchin growth, and the diel pattern of feeding and foraging behavior were significantly affected by diet type. Juveniles fed dried nori gained significantly higher live weight and test diameter than those fed herbivore pellets. Juvenile urchins displayed nocturnal feeding and foraging behavior irrespective of diet types and presence/absence of coral structure. Presence/absence of coral structure did not affect growth and diel pattern of feeding and foraging behavior, but modulated habitat usage patterns. Survival of juveniles was neither affected by diet types nor the presence/absence of coral structure. This study concludes that dried nori is a superior diet to herbivore pellets for juvenile urchin culture. Since the presence of coral structure influenced habitat usage patterns, provision of rugose structure in captivity has the potential to convey the innate shelter seeking behavior of juvenile urchins.

The SpTransformer (SpTrf) gene family encodes a set of proteins that function in the sea urchin immune system. The gene sequences have a series of internal repeats in a mosaic pattern that is characteristic of this family. This mosaic pattern necessitates the insertion of large gaps, which has made alignments of the deduced protein sequences computationally difficult such that only manual alignments have been reported previously. Because manual alignments are time consuming for evaluating newly available SpTrf sequences, computational approaches were evaluated for the sequences reported previously. Furthermore, because two different manual alignments of the SpTrf sequences are feasible because of the multiple internal repeats, it is not known whether additional alternative alignments can be identified using different approaches. The bioinformatic program, PRANK, was used because it was designed to align sequences with large gaps and indels. The results from PRANK show that the alignments of the internal repeats are similar to those done manually, suggesting multiple feasible alignments for some regions. GUIDANCE based analysis of the alignments identified regions that were excellent and other regions that failed to align. This suggests that computational approaches have limits for aligning the SpTrf sequences that include multiple repeats and that require inserted gaps. Furthermore, it is unlikely that alternative alignments for the full-length SpTrf sequences will be identified.

Background Irregular echinoids are ecosystem engineers with diverse functional services. Documenting present-day distribution of those widespread organisms is important for understanding their ecological significance and enhancing our ability to interpret their rich fossil record. Methods This study summarizes SCUBA surveys of clypeasteroid and spatangoid echinoids conducted in 2020 and 2021 along the central part of the Florida Keys. The survey included observations on both live and dead specimens, their distribution, habitat preferences, abundance, and live-dead comparison. Results Echinoids were found at 17 out of 27 examined sites (63%) and occurred across a wide range of habitats including coastal seagrass meadows, subtidal sand and seagrass settings of the Hawk Channel, backreef sands, and fine muddy sands of deeper forereef habitats. The encountered species, both dead and alive, included Clypeaster rosaceus (four sites), Clypeaster subdepressus (five sites), Encope michelini (three sites), Leodia sexiesperforata (eight sites), Meoma ventricosa (nine sites), and Plagiobrissus grandis (four sites). All sites were dominated by one species, but some sites included up to five echinoid species. Live-dead fidelity was high, including a good agreement in species composition of living and dead assemblages, congruence in species rank abundance, and overlapping spatial distribution patterns. This high fidelity may either reflect long-term persistence of local echinoid populations or fragility of echinoid tests that could prevent post-mortem transport and the formation of time-averaged death assemblages. Regardless of causative factors, the live-dead comparisons suggest that irregular echinoid assemblages, from settings that are comparable to the study area, may provide a fossil record with a high spatial and compositional fidelity. The survey of live fauna is consistent with past regional surveys in terms of identity of observed species, their rank abundance, and their spatial distribution patterns. The results suggest that despite increasingly frequent hurricanes, active seasonal fisheries, massive tourism, and urban development, irregular echinoids continue to thrive across a wide range of habitats where they provide diverse ecosystem services by oxygenating sediments, recycling organic matter, supporting commensal organisms, and providing food to predators. Results reported here document the present-day status of local echinoid populations and should serve as a useful reference point for assessing future regional changes in echinoid distribution and abundance.

In this work, we used Nanostring N-counter technology, to evaluate the mRNA expression level of more than 330 regulatory genes over 34 time points covering the first three days of development of the sea urchin larvae. The hierarchical clustering of the mRNAs expression levels has identified groups corresponding to the major developmental landmarks (e.g. maternal to zygotic transition and gastrulation). Furthermore, comparison with previous experiments indicates high reproducibility of mRNA level temporal dynamics across batches. Finally, we generated an online tool to visualise gene expression during sea urchin larval development. The site can be accessed at and https://www621.lamp.le.ac.uk/nanostring_app/nanostring/.

Echinoderm embryos have been model systems for cell and developmental biology for over 150 years, in good part because of their optical clarity. Discoveries that shaped our understanding of fertilization, cell division and cell differentiation were only possible because of the transparency of sea urchin eggs and embryos, which allowed direct observations of intracellular structures. More recently, live imaging of sea urchin embryos, coupled with fluorescence microscopy, has proven pivotal to uncovering mechanisms of epithelial to mesenchymal transition, cell migration and gastrulation. However, live imaging has mainly been performed on sea urchin embryos, while echinoderms include numerous experimentally tractable species that present interesting variation in key aspects of morphogenesis, including differences in embryo compaction and mechanisms of blastula formation. The study of such variation would allow us not only to understand how tissues are formed in echinoderms, but also to identify which changes in cell shape, cell-matrix and cell-cell contact formation are more likely to result in evolution of new embryonic shapes. Here we argue that adapting live imaging techniques to more echinoderm species will be fundamental to exploit such an evolutionary approach to the study of morphogenesis, as it will allow measuring differences in dynamic cellular behaviors - such as changes in cell shape and cell adhesion - between species. We briefly review existing methods for live imaging of echinoderm embryos and describe in detail how we adapted those methods to allow long-term live imaging of several species, namely the sea urchin Lytechinus pictus and the sea stars Patiria miniata and Patiriella regularis. We outline procedures to successfully label, mount and image early embryos for 10–16 h, from cleavage stages to early blastula. We show that data obtained with these methods allows 3D segmentation and tracking of individual cells over time, the first step to analyze how cell shape and cell contact differ among species. The methods presented here can be easily adopted by most cell and developmental biology laboratories and adapted to successfully image early embryos of additional species, therefore broadening our understanding of the evolution of morphogenesis.

Massive harmful algal blooms (HABs) have increased the risk of marine organisms encountering the dinoflagellate toxin, okadaic acid (OA). Strongylocentrotus intermedius , a globally significant benthic aquaculture species, has a large appetite for benthic algae. During red tide events, there is a high risk of red tide toxin accumulation. This study systematically evaluated the potential impact of short-term OA exposure on the behavior and physiological functions of juvenile S. intermedius. From typical (5 μg/L) to extreme OA concentrations (20 μg/L) during HAB outbreaks, OA exposure gradually inhibited a series of tube foot-related behaviors (sheltering, foraging, righting, and tube-foot tenacity). At OA concentrations during HAB outbreaks (5 μg/L), the tube foot function of S. intermedius was progressively inhibited. Further physiological indicator analyses revealed that the activity of antioxidants increased over a short period to prevent damage from reactive oxygen species induced by OA. However, OA ultimately suppressed the immune response of S. intermedius , leading to apoptosis. Although HAB-associated concentrations of OA (5 μg/L) did not induce a continuous increase in the integrated biological response index of S. intermedius , this study speculated that HABs pose a future risk to echinoderm species. Notably, principal component analysis results showed that OA exposure eventually induced significant changes in the production of O2−, malondialdehyde, and total glutathione, as well as in glutathione S-transferase activity and caspase-7, -8, and -9 levels. This study provides preliminary evidence of OA's toxic effects on sea urchins and essential data for urgent risk assessments of algal toxin pollution in aquaculture during HABs. [Display omitted] • OA inhibits tube-foot-related behaviors of S. intermedius. • OA induces oxidative stress. • OA suppresses immune response and activates apoptosis. • High concentrations of OA lead to a continuous increase in the IBR index of S. intermedius. [ABSTRACT FROM AUTHOR]

NF-κB (Nuclear factor-kappa B) family proteins are versatile transcription factors that play crucial regulatory roles in cell development, growth, apoptosis, inflammation, and immune response. However, there is limited research on the function of these key genes in echinoderms. In this study, an NF-κB family gene (SiRel) was identified in sea urchin Strongylocentrotus intermedius. The gene has an open reading frame length of 1809 bp and encodes for 602 amino acids. Domain prediction results revealed that the N-terminal of SiRel protein encodes a conserved Rel homology domain (RHD), including the RHD-DNA binding domain and the RHD-dimerization domain. Multiple sequence comparison results showed that the protein sequences of these two domains were conserved. Phylogenetic analysis indicated that SiRel clustered with Strongylocentrotus purpuratus p65 protein and Rel protein of other echinoderms. Results from quantitative real-time PCR demonstrated detectable SiRel mRNA expression in all tested sea urchin tissues, with the highest expression level found in the gills. And SiRel mRNA expression levels were significantly induced after LPS (Lipopolysaccharide) and poly(I:C) (Polyinosinic:polycytidylic acid) stimulation. In addition, SiRel protein expression can be found in cytoplasm and nucleus of HEK293T cells. Co-immunoprecipitation results showed that SiRel could interact with sea urchin IκB (Inhibitor of NF-κB) protein. Western blotting and dual-luciferase reporter gene assay results indicated that overexpression of SiRel in HEK293T cells could impact the phosphorylation levels of JNK (c-Jun N-terminal kinase) and Erk1/2 (Extracellular signal-regulated kinases1/2) and activate interleukin-6 (IL-6), activating protein 1 (AP-1), interferon (IFN)α/β/γ, and signal transducer and activator of transcription 3 (STAT3) reporter genes in HEK293T cells. In conclusion, this study reveals that SiRel plays an important role in the innate immune response of sea urchins and enriches our understanding of comparative immunology theory. • The first Rel homologous gene (SiRel) was identified in sea urchin Strongylocentrotus intermedius. • SiRel expression was induced by LPS and poly(I:C) challenge. • SiRel could interact with sea urchin IκB protein. • Overexpression of SiRel in HEK293T cells could impacte JNK and Erk1/2 phosphorylation levels. • Overexpression of SiRel in HEK293T cells could activate IL-6 , AP-1 , IFNα/β/γ , and STAT3 reporter genes. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) is a recognized source of anthropogenic disturbance, although its effects on biological systems have not been fully explored. Within marine ecosystems, coastal areas are the most impacted by ALAN. Here, we focused on the Mediterranean sea urchin Paracentrotus lividus , which has a crucial role in shaping benthic ecosystems. Our objective was to investigate if ALAN affects the nocturnal locomotor behavior of P. lividus. A semi-controlled field study was conducted along a rocky shore near a promenade lit at night. Results suggested a potential impact of ALAN on the locomotor behavior of sea urchins. Individuals of P. lividus tended to move away from the light sources while its directions in dark conditions were uniform. Their locomotor performance, in presence of ALAN, was characterized by shorter latency time, lower sinuosity and higher mean speed at increasing light intensity, with potential cascading effect at the ecosystem level. [Display omitted] • Coastal areas are among the most impacted by artificial light at night (ALAN). • ALAN may affect the nocturnal behavior of the sea urchin Paracentrotus lividus. • P. lividus tended to move away from the light sources. • Under ALAN, locomotor performance of P. lividus changed at increasing light intensity. • Results highlight potential cascading effects at the ecosystem level. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effects of temperature alterations on zinc and cadmium toxicity on early development of Paracentrotus lividus (Echinodermata: Echinoidea). For this reason, P. lividus embryos incubated in 18°C (standard temperature), 21°C and 24°C for 72 hours, were exposed to Zn (10" M - 10 5 M) and Cd (10 6 M - 3x10-4 M). The EC50 values for zinc were found to be 0.48 (0.43504.)mg L-1 at 18°C; 0.19 (0.16-0.23) mg L-1 at 21°C and 0.19 (0.17-0.22) mg L-1 at 24°C. The EC50 values for cadmium were found to be 1.88 (1.80-1.96) mg L-1 at 18°C; 1.26 (1.04-1.54) mg L-1 21°C and 0.72 (0.63-0.83) mg L-1 at 24°C. These results confirm that the sublethal embryotoxic effects of cadmium and zinc increased with increasing temperatures. Zinc was found to be more toxic than cadmium at all temperatures tested on the embryonic development of P. lividus. [ABSTRACT FROM AUTHOR]

Background: Understanding how gene regulatory networks (GRNs) control developmental progression is a key to the mechanistic understanding of morphogenesis. The sea urchin larval skeletogenesis provides an excellent platform to tackle this question. In the early stages of sea urchin skeletogenesis, skeletogenic genes are uniformly expressed in the skeletogenic lineage. Yet, during skeletal elongation, skeletogenic genes are expressed in distinct spatial sub‐domains. The regulation of differential gene expression during late skeletogenesis is not well understood. Results: Here we reveal the dynamic expression of the skeletogenic regulatory genes that define a specific regulatory state for each pair of skeletal rods, in the sea urchin Paracentrotus lividus. The vascular endothelial growth factor (VEGF) signaling, essential for skeleton formation, specifically controls the migration of cells that form the postoral and distal anterolateral skeletogenic rods. VEGF signaling also controls the expression of regulatory genes in cells at the tips of the postoral rods, including the transcription factors Pitx1 and MyoD1. Pitx1 activity is required for normal skeletal elongation and for the expression of some of VEGF target genes. Conclusions: Our study illuminates the fine‐tuning of the regulatory system during the transition from early to late skeletogenesis that gives rise to rod‐specific regulatory states. Key Findings: The skeletogenic transcription factors form specific regulatory states in various skeletogenic sub‐populations.Late VEGF signaling controls the regulatory states at the tips of the post‐oral and anterolateral skeletal rods.VEGF signaling controls the expression of the transcription factors, MyoD1 and Pitx1.Pitx1 activity is required for normal skeletal elongation and for the expression of some of VEGF target genes. [ABSTRACT FROM AUTHOR]