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Sea urchins are basal deuterostomes that share key molecular components of innate immunity with vertebrates. They are a powerful model for the study of innate immune system evolution and function, especially during early development. Here we characterize the morphology and associated molecular markers of larval immune cell types in a newly developed model sea urchin, Lytechinus pictus. We then challenge larvae through infection with an established pathogenic Vibrio and characterize phenotypic and molecular responses. We contrast these to the previously described immune responses of the purple sea urchin Strongylocentrotus purpuratus. The results revealed shared cellular morphologies and homologs of known pigment cell immunocyte markers (PKS, srcr142) but a striking absence of subsets of perforin‐like macpf genes in blastocoelar cell immunocytes. We also identified novel patterning of cells expressing a scavenger receptor cysteine rich (SRCR) gene in the coelomic pouches of the larva (the embryonic stem cell niche). The SRCR signal becomes further enriched in both pouches in response to bacterial infection. Collectively, these results provide a foundation for the study of immune responses in L. pictus. The characterization of the larval immune system of this rapidly developing and genetically enabled sea urchin species will facilitate more sophisticated studies of innate immunity and the crosstalk between the immune system and development. [ABSTRACT FROM AUTHOR]

Sea urchins, ecologically important marine species, host a complex gut microbiota that plays a significant role in their digestion, nutrient acquisition, and overall health. The gut microbes, along with endogenous enzymes, facilitate the breakdown of macroalgae and other food sources. Environmental factors, including temperature, salinity, and habitat type, can greatly influence the microbial communities within sea urchins. Dietary variations can also lead to shifts in the abundance and composition of intestinal bacteria, highlighting the strong connection between diet and gut microbiota. The sea urchin's unique anatomy and digestive system adaptations contribute to their ability to process and absorb nutrients efficiently, supporting their varied diets. Gut microbes not only participate in the decomposition of complex carbohydrates, but also in detoxifying compounds and mitigating the impacts of inhospitable environments. Further research is needed to fully understand the intricate relationships between sea urchin species, their habitats, diets, and gut microbiota composition. A deeper understanding of these interactions may inform sustainable management and aquaculture strategies, ensure the long‐term viability of economically valuable sea urchin species, and provide insights into their ecological roles and adaptability to changing environments. [ABSTRACT FROM AUTHOR]

The die‐off of the long‐spined sea urchin Diadema antillarum in the 1980s highlighted its crucial role as a primary grazer in tropical western Atlantic coral reefs. However, natural recovery has been slow, exacerbated by a new die‐off in 2022. Interest in actively restoring D. antillarum populations has grown with the emergence of culture and rearing techniques. Restocking reefs with laboratory‐reared urchins shows potential for enhancing coral reef resilience by reducing algal cover and promoting coral settlement, but success rates vary. Predation and migration contribute to low retention rates, with distinguishing between them is challenging. In this study near Saba, Caribbean Netherlands, we released 200 laboratory‐reared D. antillarum on a reef and monitored for D. antillarum retention and potential D. antillarum predator presence and interaction for 35 days. Only 40% of the urchins were still present on the reef after day one. The Spanish hogfish Bodianus rufus was identified as the primary daytime predator, responsible for nine direct predation events. No nighttime predation was observed, but interaction with a batwing coral crab Carpilius corallinus was noted. These insights can help optimize future restocking attempts and emphasize the importance of assessing predator presence beforehand. Reefs with high abundances of predators such as Spanish hogfish should be avoided for D antillarum restocking. In addition, before being released, lab‐reared animals should be given time to acclimate to conditions in the wild by being placed in protected in situ cages. Here, they could also grow to larger sizes that are less vulnerable to predation. [ABSTRACT FROM AUTHOR]

Background: Sea urchins have contributed greatly to knowledge of fertilization, embryogenesis, and cell biology. However, until now, they have not been genetic model organisms because of their long generation times and lack of tools for husbandry and gene manipulation. We recently established the sea urchin Lytechinus pictus, as a multigenerational model Echinoderm, because of its relatively short generation time of 4–6 months and ease of laboratory culture. To take full advantage of this new multigenerational species, methods are needed to biobank and share genetically modified L. pictus sperm. Results: Here, we describe a method, based on sperm ion physiology that maintains L. pictus and Strongylocentrotus purpuratus sperm fertilizable for at least 5–10 weeks when stored at 0°C. We also describe a new method to cryopreserve sperm of both species. Sperm of both species can be frozen and thawed at least twice and still give rise to larvae that undergo metamorphosis. Conclusions: The simple methods we describe work well for both species, achieving >90% embryo development and producing larvae that undergo metamorphosis to juvenile adults. We hope that these methods will be useful to others working on marine invertebrate sperm. Key Findings: Sperm can maintain fertilizing capacity ex vivo for 5‐10 weeks when stored at 0oC.When freezing in liquid nitrogen no stepwise addition of cryoprotectant, or stepwise drop in temperature are required.A standard fertilization assay is presented to score cleavage stage sea urchin embryos produced by cryopreserved sperm.Sperm frozen and thawed more than once can produce larvae. [ABSTRACT FROM AUTHOR]

Evechinus chloroticus (commonly known as kina) is a sea urchin species endemic to New Zealand. Its roe is a culinary delicacy to the indigenous Māori and a globally exported food product. Echinochrome A (Ech A) is a bioactive compound isolated from the waste product of kina shells and spines; however, the molecular mechanisms of Ech A bioactivity are not well understood, partly due to Ech A never being studied using unbiased genome‐wide analysis. To explore the high‐value pharmaceutical potential of kina food waste, we obtained unbiased functional genomic and proteomic profiles of yeast cells treated with Echinochrome A. Abundance was measured for 4100 proteins every 30 min for four hours using fluorescent microscopy, resulting in the identification of 92 proteins with significant alterations in protein abundance caused by Ech A treatment that were over‐represented with specific changes in DNA replication, repair and RNA binding after 30 min, followed by specific changes in the metabolism of metal ions (specifically iron and copper) from 60–240 min. Further analysis indicated that Ech A chelated iron, and that iron supplementation negated the growth inhibition caused by Ech A. Via a growth‐based genome‐wide analysis of 4800 gene deletion strains, 20 gene deletion strains were sensitive to Ech A in an iron‐dependent manner. These genes were over‐represented in the cellular response to oxidative stress, suggesting that Ech A suppressed growth inhibition caused by oxidative stress. Unexpectedly, genes integral to cardiolipin and inositol phosphate biosynthesis were required for Ech A bioactivity. Overall, these results identify genes, proteins, and cellular processes mediating the bioactivity of Ech A. Moreover, we demonstrate unbiased genomic and proteomic methodology that will be useful for characterizing bioactive compounds in food and food waste. [ABSTRACT FROM AUTHOR]

Background: Some marine invertebrate organisms are considered not to develop tumors due to unknown mechanisms. To gain an initial insight into how tumor‐related genes may be expressed and function during marine invertebrate development, we here leverage sea urchin embryos as a model system and characterize the expressions of Myc and p53/p63/p73 which are reported to function synergistically in mammalian models as an oncogene and tumor suppressor, respectively. Results: During sea urchin embryogenesis, a combo gene of p53/p63/p73 is found to be maternally loaded and decrease after fertilization both in transcript and protein, while Myc transcript and protein are zygotically expressed. p53/p63/p73 and Myc proteins are observed in the cytoplasm and nucleus of every blastomere, respectively, throughout embryogenesis. Both p53/p63/p73 and Myc overexpression results in compromised development with increased DNA damage after the blastula stage. p53/p63/p73 increases the expression of parp1, a DNA repair/cell death marker gene, and suppresses endomesoderm gene expressions. In contrast, Myc does not alter the expression of specification genes or oncogenes yet induces disorganized morphology. Conclusions: p53/p63/p73 appears to be important for controlling cell differentiation, while Myc induces disorganized morphology yet not through conventional oncogene regulations or apoptotic pathways during embryogenesis of the sea urchin. Key Findings: p53/p63/p73 protein is maternally loaded, while Myc protein expression starts zygotically.p53/p63/p73 and Myc proteins are localized in the cytoplasm and nucleus of all blastomeres, respectively, during early embryogenesis.Overexpression of p53/p63/p73 and Myc increases their nuclear localization and DNA damage in the resultant embryos.p53/p63/p73 appears to suppress gene expressions for cell specification differentiation, while Myc has no impact on specification genes yet causes disorganized morphology and embryonic death. [ABSTRACT FROM AUTHOR]

An important goal of many studies in molecular ecology is to utilize molecular tools to elucidate how critical traits like metabolism and growth are affected by environmental stressors and how organisms offset these stresses by adaptive molecular‐level responses. Stress from food deprivation may be critical for early developmental stages that require a continued supply of substrates for energy metabolism and growth if development is to be completed. In a 'From the Cover' article in this issue of Molecular Ecology, Li et al. (2023) examined the effects of withholding food (unicellular algae) on 10 traits of larvae of the purple sea urchin (Strongylocentrotus purpuratus), ranging from the molecular level (gene expression) to morphology. Overall, this study sheds new light on the plasticity of larval development and the tight linkages that exist among traits as they respond to changes in food availability. Importantly, shifts in the sources of food utilized under different dietary treatments show the plasticity of these larvae to alter reliance on endogenous energy stores and dissolved organic matter (DOM) as algae deprivation continues. The effects of global change on the amounts and phenology of productivity in the seas make this type of integrated, multi‐level analysis an important tool for predicting the future states of marine ecosystems. [ABSTRACT FROM AUTHOR]

The dissolution of anthropogenic carbon dioxide (CO2) in seawater has altered its carbonate chemistry in the process of ocean acidification (OA). OA affects the viability of marine species. In particular, calcifying organisms and their early planktonic larval stages are considered vulnerable. These organisms often utilize energy reserves for metabolism rather than growth and calcification as supported by bulk RNA‐sequencing (RNA‐seq) experiments. Yet, transcriptomic profiling of a bulk sample reflects the average gene expression of the population, neglecting the variations between individuals, which forms the basis for natural selection. Here, we used single‐embryo RNA‐seq on larval sea urchin Heliocidaris crassispina, which is a commercially and ecologically valuable species in East Asia, to document gene expression changes to OA at an individual and family level. Three paternal half‐sibs groups were fertilized and exposed to 3 pH conditions (ambient pH 8.0, 7.7 and 7.4) for 12 h prior to sequencing and oxygen consumption assay. The resulting transcriptomic profile of all embryos can be distinguished into four clusters, with differences in gene expressions that govern biomineralization, cell differentiation and patterning, as well as metabolism. While these responses were influenced by pH conditions, the male identities also had an effect. Specifically, a regression model and goodness of fit tests indicated a significant interaction between sire and pH on the probability of embryo membership in different clusters of gene expression. The single‐embryo RNA‐seq approach is promising in climate stressor research because not only does it highlight potential impacts before phenotypic changes were observed, but it also highlights variations between individuals and lineages, thus enabling a better determination of evolutionary potential. [ABSTRACT FROM AUTHOR]

Tool use is a remarkable animal behaviour, and the investigation of this phenomenon in fishes is a relatively new and growing field. The graphic tuskfish Choerodon graphicus (De Vis 1885) has previously been documented using anvils but the extent and variability of this tool‐use behaviour remains poorly understood. In this study, we investigated whether C. graphicus breaks open crustaceans and/or sea urchins on anvils in different microhabitats and/or locations. We also inspected two previously identified anvils for evidence of long‐term anvil use. Three individual C. graphicus were observed breaking open sea urchins on dead coral anvils in a coral rubble microhabitat at Île aux Canards, New Caledonia. They produced visual and auditory cues while carrying out tool‐use behaviour and these cues often attracted attendant fishes. Notably, two anvils appeared to have been used by one or more tool‐using C. graphicus for years at Îlot Maître, New Caledonia. These findings suggest that tool‐use behaviour is both innate and learned and is a prey‐handling method of choice used by individuals that learn to specialise in large prey items from a few underutilised hard‐shelled prey species. Furthermore, the findings show that specific anvils can be used long‐term and also suggest that individual wrasses may carry out tool‐use behaviour long‐term. The study provides new insights into the feeding ecology and social behaviour of C. graphicus and underscores the need to further investigate the extent and variability of tool use in fishes. [ABSTRACT FROM AUTHOR]

Microbes play a critical role in the development and health of marine invertebrates, though microbial dynamics across life stages and host generations remain poorly understood in most reef species, especially in the context of climate change. Here, we use a 4‐year multigenerational experiment to explore microbe–host interactions under the Intergovernmental Panel on Climate Change (IPCC)‐forecast climate scenarios in the rock‐boring tropical urchin Echinometra sp. A. Adult urchins (F0) were exposed for 18 months to increased temperature and pCO2 levels predicted for years 2050 and 2100 under RCP 8.5, a period which encompassed spawning. After rearing F1 offspring for a further 2 years, spawning was induced, and F2 larvae were raised under current day and 2100 conditions. Cross‐generational climate effects were also explored in the microbiome of F1 offspring through a transplant experiment. Using 16S rRNA gene sequence analysis, we determined that each life stage and generation was associated with a distinct microbiome, with higher microbial diversity observed in juveniles compared to larval stages. Although life‐stage specificity was conserved under climate conditions projected for 2050 and 2100, we observed changes in the urchin microbial community structure within life stages. Furthermore, we detected a climate‐mediated parental effect when juveniles were transplanted among climate treatments, with the parental climate treatment influencing the offspring microbiome. Our findings reveal a potential for cross‐generational impacts of climate change on the microbiome of a tropical invertebrate species. [ABSTRACT FROM AUTHOR]

Objective: The presence of heavy metals in seawater is a major challenge for hatchery culture of sea urchin larvae due to their sensitivity to metal pollution. The impact of heavy metals in seawater for sensitive marine larviculture could be minimized via chelation of metals using chemical compounds such as ethylenediaminetetraacetic acid (EDTA). Methods: In this study the effects of EDTA were tested for the long‐spined sea urchin Diadema antillarum during larviculture at two concentrations (10 μM and 50 μM) and two exposure durations (6 and 24 days postfertilization). Growth and survival of larvae were evaluated as response variables. Result: Significant differences in growth and survival of larvae were found among the treatments at different EDTA concentrations and exposure durations. The 10‐μM EDTA treatment enhanced growth and survival of larvae relative to control for both exposure durations. The 50‐μM EDTA treatment was unsuitable for long‐spined sea urchin larviculture due to reductions in growth and survival. Conclusion: The use of 10 μM EDTA during embryo incubation and larviculture is expected to improve long‐spined sea urchin larval fitness, leading to improved hatchery production. Impact statementLong‐spinged sea urchins are ecologically important on Caribbean coral reefs and their larvae are highly sensitive to environmental contaminants. This study identifies a simple addition to an established aquaculture system that may aid production of this species. [ABSTRACT FROM AUTHOR]

Objective: The production of echinoid larvae and juveniles is required in both wild‐population enhancement programs and full life‐cycle culture. Many echinoid species of commercial interest spawn only once or twice a year, however, restricting temporal access to viable broodstock. High‐energy/high‐protein formulated feeds have been used for gonad enhancement of a variety of echinoid species, but the goal of that activity has always been to produce premature gonads, which the market requires, not the production of mature gonads for breeding. The present investigation, originally established to examine gonad enhancement, took advantage of a spawning event to assess the efficacy of a formulated feed to extend the spawning period or reduce gonad recovery time after spawning in a commercially relevant echinoid, the green sea urchin Strongylocentrous droebachiensis. Methods: Urchins held in suspended sea cages were fed either a formulated, commercial, pelleted urchin diet or bull kelp Nereocystis luetkeana over 12 weeks, with survival, somatic growth, gonad quantity (wet weight, yield), and gonad quality (presence/absence of gametes) being examined over time. Result: Survivorship after 12 weeks was high, little difference being observed between the two diets (mean ± SE: 98.2 ± 1.1% and 95.9 ± 1.9% for kelp and formulated feed, respectively). There was no significant difference in somatic growth between the two treatments, but the formulated feed led to significantly higher gonad wet weight and yield than kelp at the end of the study. When compared with kelp, the formulated feed may have led to earlier spawning and quicker gonad recovery and prevented the complete spawning of all urchins, thus extending the period of gamete availability. Conclusion: Formulated feeds may have the potential to maintain reproductively active broodstock over an extended time, allowing expansion of the period in which echinoid larvae and juveniles can be produced. Impact statementFormulated feeds may have the potential to maintain reproductively active urchin broodstock over an extended time, allowing expansion of the period in which urchin larvae and juveniles can be produced by urchin farmers. [ABSTRACT FROM AUTHOR]

CCCTC‐binding factor (CTCF), an insulator protein with 11 zinc fingers, is enriched at the boundaries of topologically associated domains (TADs) in eukaryotic genomes. In this study, we isolated and analyzed the cDNAs encoding HpCTCF, the CTCF homolog in the sea urchin Hemicentrotus pulcherrimus, to investigate its expression patterns and functions during the early development of sea urchin. HpCTCF contains nine zinc fingers corresponding to fingers 2–10 of the vertebrate CTCF. Expression pattern analysis revealed that HpCTCF mRNA was detected at all developmental stages and in the entire embryo. Upon expressing the HpCTCF‐GFP fusion protein in early embryos, we observed its uniform distribution within interphase nuclei. However, during mitosis, it disappeared from the chromosomes and subsequently reassembled on the chromosome during telophase. Moreover, the morpholino‐mediated knockdown of HpCTCF resulted in mitotic arrest during the morula to blastula stage. Most of the arrested chromosomes were not phospholylated at serine 10 of histone H3, indicating that mitosis was arrested at the telophase by HpCTCF depletion. Furthermore, impaired sister chromatid segregation was observed using time‐lapse imaging of HpCTCF‐knockdown embryos. Thus, HpCTCF is essential for mitotic progression during the early development of sea urchins, especially during the telophase‐to‐interphase transition. However, the normal development of pluteus larvae in CRISPR‐mediated HpCTCF‐knockout embryos suggests that disruption of zygotic HpCTCF expression has little effect on embryonic and larval development. [ABSTRACT FROM AUTHOR]

How strongly predators and prey interact is both notoriously context dependent and difficult to measure. Yet across taxa, interaction strength is strongly related to predator size, prey size and prey density, suggesting that general cross‐taxonomic relationships could be used to predict how strongly individual species interact.Here, we ask how accurately do general size‐scaling relationships predict variation in interaction strength between specific species that vary in size and density across space and time?To address this question, we quantified the size and density dependence of the functional response of the California spiny lobster Panulirus interruptus, foraging on a key ecosystem engineer, the purple sea urchin Strongylocentrotus purpuratus, in experimental mesocosms. Based on these results, we then estimated variation in lobster–urchin interaction strength across five sites and 9 years of observational data. Finally, we compared our experimental estimates to predictions based on general size‐scaling relationships from the literature.Our results reveal that predator and prey body size has the greatest effect on interaction strength when prey abundance is high. Due to consistently high urchin densities in the field, our simulations suggest that body size—relative to density—accounted for up to 87% of the spatio‐temporal variation in interaction strength. However, general size‐scaling relationships failed to predict the magnitude of interactions between lobster and urchin; even the best prediction from the literature was, on average, an order of magnitude (+18.7×) different than our experimental predictions.Harvest and climate change are driving reductions in the average body size of many marine species. Anticipating how reductions in body size will alter species interactions is critical to managing marine systems in an ecosystem context. Our results highlight the extent to which differences in size‐frequency distributions can drive dramatic variation in the strength of interactions across narrow spatial and temporal scales. Furthermore, our work suggests that species‐specific estimates for the scaling of interaction strength with body size, rather than general size‐scaling relationships, are necessary to quantitatively predict how reductions in body size will alter interaction strengths. [ABSTRACT FROM AUTHOR]

Localized mRNA translation is a biological process that allows mRNA to be translated on‐site, which is proposed to provide fine control in protein regulation, both spatially and temporally within a cell. We recently reported that Vasa, an RNA‐helicase, is a promising factor that appears to regulate this process on the spindle during the embryonic development of the sea urchin, yet the detailed roles and functional mechanisms of Vasa in this process are still largely unknown. In this review article, to elucidate these remaining questions, we first summarize the prior knowledge and our recent findings in the area of Vasa research and further discuss how Vasa may function in localized mRNA translation, contributing to efficient protein regulation during rapid embryogenesis and cancer cell regulation. [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]

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]

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]

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]

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]

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]

Sea urchins have a long history as model organisms in biology, but their use in genetics is limited because of their long breeding cycle. In sea urchin genetics, genome editing technology was first established in Hemicentrotus pulcherrimus, whose genome has already been published. However, because this species also has a long breeding cycle, new model sea urchins that are more suitable for genetics have been sought. Here, we report a draft genome of another Western Pacific species, Temnopleurus reevesii, which we established as a new model sea urchin recently since this species has a comparable developmental process to other model sea urchins but a short breeding cycle of approximately half a year. The genome of T. reevesii was assembled into 28,742 scaffold sequences with an N50 length of 67.6 kb and an estimated genome size of 905.9 Mb. In the assembled genome, 27,064 genes were identified, 23,624 of which were expressed in at least one of the seven developmental stages. To provide genetic information, we constructed the genome database TrBase (https://cell-innovation.nig.ac.jp/Tree/). We also constructed the Western Pacific Sea Urchin Genome Database (WestPac‐SUGDB) (https://cell-innovation.nig.ac.jp/WPAC/) with the aim of establishing a portal site for genetic information on sea urchins in the West Pacific. This site contains genomic information on two species, T. reevesii and H. pulcherrimus, and is equipped with homology search programs for comparing the two datasets. Therefore, TrBase and WestPac‐SUGDB are expected to contribute not only to genetic research using sea urchins but also to comparative genomics and evolutionary research. [ABSTRACT FROM AUTHOR]

Echinoderms, including sea urchins and starfish, have played important roles in cell, developmental and evolutionary biology research for more than a century. However, since most of them take a long time to mature sexually and their breeding seasons are limited, it has been difficult to obtain subsequent generations in the laboratory, resulting in them not being recognized as model organisms in recent genetics research. To overcome this issue, we maintained and obtained gametes from several nonmodel sea urchins in Japan and finally identified Temnopleurus reevesii as a suitable model for sea urchin genetics. Genomic and transcriptomic information was obtained for this model, and the DNA database TrBase was made publicly available. In this review, we describe how we found this species useful for biological research and show an example of CRISPR/Cas9 based knockout sea urchin. [ABSTRACT FROM AUTHOR]

Herbivores play an essential role in the health and recovery of a coral reef ecosystem. The lack of recovery of the keystone herbivore Diadema antillarum has had long‐lasting effects, evidenced with many reefs persisting in algal dominance. This study restocked 756 lab‐reared D. antillarum to four coral reefs on the east and south coast of Puerto Rico. Sea urchins were placed in experimental plots ("corrals") for 2 months, and the change in benthic composition was measured. Significant changes in the benthic structure were observed during the first week after the restocking. Significant reductions of fleshy macroalgae (Dictyota spp.) and thick turf algal/sediment mats (TAS), both unsuitable substrates (e.g. coral settlement), contributed to this change. Also, restocked D. antillarum significantly reduced the cover of encrusting red algae, Ramicrusta spp. By the end of the study, the abundance of fleshy macroalgae decreased by a mean of 77% (max of 100%) and Ramicrusta and TAS by 53% (max 71%) and 56% (max 100%), respectively. Clean substrate ("pavement"), crustose coralline algae (CCA), and filamentous turf algae increased between one to two orders of magnitude. The restoration of native sea urchins is a non‐invasive and useful approach to aid in the mitigation of algae, especially potentially dangerous alga like Ramicrusta. The results of this study highlight the importance of herbivores in improving the conditions on coral reefs. [ABSTRACT FROM AUTHOR]

Background: Sea urchins are model organisms for studying the spatial‐temporal control of gene activity during development. The Southern California species, Lytechinus pictus, has a sequenced genome and can be raised in the laboratory from egg to egg in 4 to 5 months. Results: Here, we present new techniques for generating parthenogenetic larvae of this species and include a gallery of photomicrographs of morphologically abnormal larvae that could be used for transcriptomic analysis. Conclusions: Comparison of gene expression in parthenogenotes to larvae produced by fertilization could provide novel insights into gene expression controls contributed by sperm in this important model organism. Knowledge gained from transcriptomics of sea urchin parthenogenotes could contribute to parthenogenetic studies of mammalian embryos. Key Findings: Our paper reintroduces the potential value of studying parthenogenotes since the last such paper was published 46 years ago, before transcriptomics existed.This paper describes the simple culture of Lytechinus pictus in petri plates in the absence of large quantities of seawater and continuous stirring motors.This paper provides the first photomicrographs of parthenogenetic sea urchin larvae in the developmental biology literature.Studying transcriptomics in these parthenogenotes might illuminate controls the sperm genome contributes to gene activation during development.Processes such as the activation of protein and DNA synthesis would also be interesting to study in parthenogenote sea urchin embryos and larvae. [ABSTRACT FROM AUTHOR]

An ultimate benefit of marine protected areas (MPAs) is to reverse trophic cascades caused by human‐driven collapse of critical ecological interactions. Here we demonstrate that, despite a small scale (0.28 km2) and not being fully protected, an MPA with strict fishing management and habitat enhancement by artificial reefs (ARs) in southwest Japan can lead to well‐established macroalgal communities on widespread sea urchin barrens through cascading effects of predator recovery. Areas with low urchin densities occurred in and around daytime lobster (Panulirus japonicus) shelters primarily formed by quarry‐rock ARs inside the MPA. We confirmed in the laboratory that lobsters preyed on two dominant sea urchins (Echinometra sp. A and Heliocidaris crassispina), with size‐ and species‐dependent predation. The area with few urchins extended farther (˜65 m) from an AR with numerous lobsters than from a natural shelter (patch reef) with far fewer lobsters. Causation of this pattern was confirmed by a tethering experiment showing that predation on urchins was similarly high at and near lobster shelters but decreased at ˜100 m from the AR to a similar level as at an unprotected site. Time‐lapse photography revealed that predation on tethered urchins was due mostly to the largest size class of lobsters (>100 mm carapace length), which comprised only 7% of the population, highlighting the importance of large‐sized lobsters in controlling urchin abundance in localized areas adjacent to urchin‐dominated barrens. Despite an ongoing once‐a‐year fishing event permitted within the MPA, lobster populations were persistent, demonstrating that the cascading effect of the lobsters on urchins and ultimately macroalgae was robust to temporary reductions in predator population size. Erect macroalgal cover was not simply accounted for by snapshot urchin density or biomass, suggesting a hysteresis effect of the phase shifts between macroalgal dominance and urchin barren states. [ABSTRACT FROM AUTHOR]

Shifts in microbial communities represent a rapid response mechanism for host organisms to respond to changes in environmental conditions. Therefore, they are likely to be important in assisting the acclimatization of hosts to seasonal temperature changes as well as to variation in temperatures across a species' range. The Persian/Arabian Gulf is the world's warmest sea, with large seasonal fluctuations in temperature (20℃ ‐ 37℃) and is connected to the Gulf of Oman which experiences more typical oceanic conditions (<32℃ in the summer). This system is an informative model for understanding how symbiotic microbial assemblages respond to thermal variation across temporal and spatial scales. Here, we elucidate the role of temperature on the microbial gut community of the sea urchin Echinometra sp. EZ and identify microbial taxa that are tightly correlated with the thermal environment. We generated two independent datasets with a high degree of geographic and temporal resolution. The results show that microbial communities vary across thermally variable habitats, display temporal shifts that correlate with temperature, and can become more disperse as temperatures rise. The relative abundances of several ASVs significantly correlate with temperature in both independent datasets despite the >300 km distance between the furthest sites and the extreme seasonal variations. Notably, over 50% of the temperature predictive ASVs identified from the two datasets belonged to the family Vibrionaceae. Together, our results identify temperature as a robust predictor of community‐level variation and highlight specific microbial taxa putatively involved in the response to thermal environment. [ABSTRACT FROM AUTHOR]

Predictions of ectotherms' responses to global warming depend on the relationship between environmental temperature and organismal performance. To date, most predictions of thermal responses are generated from experimentally derived measures of thermal tolerances of adults or estimates of thermal niches derived from geographic distributions of adults. It is unknown how measures derived from these different approaches compare, or, as thermal performance of ectotherms varies through ontogeny, how they compare across life stages.To understand the efficacy of the temperature–performance relationship of early developmental stages as predictors of geographic range, we empirically documented the upper and lower thermal tolerance limits of embryos of eight species of ectotherms with complex life cycles.We compared the embryonic thermal tolerances of each species to that of the adults (documented in a previous study), as well as to an estimate of the thermal niche derived from adult distributions.Our results show that in all eight species the upper thermal limit estimated from embryos is significantly lower than the upper thermal limit estimated from adults. The lower thermal limit for embryos and for adult performance are similar, but the lower thermal limit for adult survival is significantly lower.Warming tolerances, calculated as the difference between upper tolerance limit and the average ambient temperature during the warmest month, for each species are also smaller for embryos (~1°C) than for adults (~5°C).These results show that thermal tolerances of early developmental stages, which are often easier to obtain for large sample sizes over an array of temperatures than are tolerances of adults, are a powerful, and potentially more accurate tool for predicting future responses to climate change. A free Plain Language Summary can be found within the Supporting Information of this article [ABSTRACT FROM AUTHOR]

Background: Doublecortin‐like kinase1 and 2 (DCLKs) are protein Ser/Thr kinases important for neuronal development. More recently, they are also reported to regulate plasticity such as cell proliferation and differentiation of stem cells and cancer cells, but the details of their functions in this biological context are still unclear. With an attempt to reveal the functions of DCLKs in plasticity regulation, we here used the sea urchin embryo that undergoes highly regulative development as an experimental model. Results: We found that both the transcripts and the proteins of DCLKs are uniformly present during early embryogenesis and with some enrichment in mesenchymal cells after gastrula stage. Knockdown of DCLKs induced general developmental delay and defects at day 2. Further, the damage on the embryo/larva induced ectopic expression of DCLKs in the ectoderm where the damage was most severe. Under a tumor‐prone or ‐suppressive condition, DCLKs expression was upregulated or downregulated, respectively, after damage. In both cases, the embryos showed severe developmental defects. Conclusions: Taken together, a transient upregulation of DCLKs appears to be involved in a damage response both during normal and abnormal development, and which could result in different phenotypes in a context dependent manner. Key Findings: DCLK1 and DLCK2 (DCLKs) are both essential for proper embryonic development in the sea urchin.Expression of DCLKs is upregulated upon damage.A fine balance of Rb1 and Vasa activities appears to be critical for tight regulation of DCLKs expression. [ABSTRACT FROM AUTHOR]

The echinoderms are a phylum of marine deuterostomes characterized by the pentaradial (five fold) symmetry of their adult bodies. Due to this unusual body plan, adult echinoderms have long been excluded from comparative analyses aimed at understanding the origin and evolution of deuterostome nervous systems. Here, we investigated the neural anatomy of early juveniles of representatives of three of the five echinoderm classes: the echinoid Paracentrotus lividus, the asteroid Patiria miniata, and the holothuroid Parastichopus parvimensis. Using whole mount immunohistochemistry and confocal microscopy, we found that the nervous system of echinoid early juveniles is composed of three main structures: a basiepidermal nerve plexus, five radial nerve cords connected by a circumoral nerve ring, and peripheral nerves innervating the appendages. Our whole mount preparations further allowed us to obtain thorough descriptions of these structures and of several innervation patterns, in particular at the level of the appendages. Detailed comparisons of the echinoid juvenile nervous system with those of asteroid and holothuroid juveniles moreover supported a general conservation of the main neural structures in all three species, including at the level of the appendages. Our results support the previously proposed hypotheses for the existence of two neural units in echinoderms: one consisting of the basiepidermal nerve plexus to process sensory stimuli locally and one composed of the radial nerve cords and the peripheral nerves constituting a centralized control system. This study provides the basis for more in‐depth comparisons of the echinoderm adult nervous system with those of other animals, in particular hemichordates and chordates, to address the long‐standing controversies about deuterostome nervous system evolution. [ABSTRACT FROM AUTHOR]

A study was conducted to investigate the effects of dietary n‐3 LC‐PUFA on the growth performance, fatty acid profile, transcription of related genes and intestinal microflora in adult sea urchin (Strongylocentrotus intermedius). Kelp (Laminaria japonica) and four formulated feeds with graded levels of n‐3 LC‐PUFA (0%, 0.5%, 0.8% and 1.0% dry diet) were prepared as the experimental diets. Each diet was randomly allocated to ten adult sea urchin individuals. The feeding period lasted for 90 days. Results showed that gonadosomatic index (GSI) of adult S. intermedius fed formulated feeds was significantly higher than that fed kelp (p < 0.05), while weight gain rate (WGR) showed no significance between kelp and feed groups (p > 0.05). Neither WGR nor GSI showed significant differences among the four feed treatments (p > 0.05). Notably, ARA and EPA in the gonads of S. intermedius fed the feeds devoid of n‐3 LC‐PUFA were comparable to that fed the feeds with 0.5% n‐3 LC‐PUFA (p > 0.05). Transcription of Elovl4 and Δ5‐desaturase in the intestine and gonad significantly decreased as dietary n‐3 LC‐PUFA increased (p < 0.05). Proteobacteria and Bacteroidetes (phylum level) and Psychromonas and Sulfurimonas (genus level) were the most abundant bacteria species in the intestine of S. intermedius. The abundance of Sulfurimonas was comparable in the S. intermedius fed kelp and the feed with 0% n‐3 LC‐PUFA, which was significantly higher than that fed the other formulated feeds (p < 0.05). These results indicated that S. intermedius seems to have a low requirement for n‐3 LC‐PUFA to sustain its normal growth and gonad development. The increased transcription of rate‐limiting enzymes (Elovl4 and Δ5‐desaturase) could be responsible for the considerable amounts of EPA and ARA in the gonads of S. intermedius when fed feeds without LC‐PUFA. The intestinal microflora were affected to a certain extent by the die categories and the n‐3 LC‐PUFA in the formulated feeds. It is speculated that some unknown bacteria in the genus of Sulfurimonas could participate in the synthesis of LC‐PUFA. [ABSTRACT FROM AUTHOR]

Background: Sea urchin embryos have been used for more than a century in the study of fertilization and early development. However, several of the species used, such as Strongylocentrotus purpuratus, have long generation times making them suboptimal for transgenerational studies. Results: Here, we present an overview of the development of a rapidly developing echinoderm species, Lytechinus pictus, from fertilization through sexual maturation. When grown at room temperature (20°C) embryos complete the first cell cycle in 90 minutes, followed by subsequent cleavages every 45 minutes, leading to hatching at 9 hours postfertilization (hpf). The swimming embryos gastrulate from 12 to 36 hpf and produce the cells which subsequently give rise to the larval skeleton and immunocytes. Larvae begin to feed at 2 days and metamorphose by 3 weeks. Juveniles reach sexual maturity at 4 to 6 months of age, depending on individual growth rate. Conclusions: This staging scheme lays a foundation for future studies in L. pictus, which share many of the attractive features of other urchins but have the key advantage of rapid development to sexual maturation. This is significant for multigenerational and genetic studies newly enabled by CRISPR‐CAS mediated gene editing. Key Findings: Here we present a complete staging scheme from fertilization through sexual maturation for the sea urchin Lytechinus pictus. This species has key advantages, chiefly rapid development to maturation, which is significant for multigeneration and genetic studies enabled by CRISPR‐CAS gene editing. [ABSTRACT FROM AUTHOR]

The increasing atmospheric CO2 concentration in the last few decades has resulted in a decrease in oceanic pH. In this study, we assessed the natural variability of pH in coastal waters off Goa, eastern Arabian Sea. pHT showed large variability (7.6–8.1) with low pH conditions during south‐west monsoon (SWM), and the variability is found to be associated with upwelling rather than freshwater runoff. Considering that marine biota inhabiting dynamic coastal waters off Goa are exposed to such wide range of natural fluctuations of pH, an acidification experiment was carried out. We studied the impact of low pH on the local population of sea urchin Stomopneustes variolaris (Lamarck, 1816). Sea urchins were exposed for 210 days to three treatments of pHT: 7.96, 7.76 and 7.46. Our results showed that S. variolaris at pHT 7.96 and 7.76 were not affected, whereas the ones at pHT 7.46 showed adverse effects after 120 days and 50% mortality by 210 days. However, even after exposure to low pH for 210 days, 50% organisms survived. Under low pH conditions (pHT 7.46), the elemental composition of sea urchin spines exhibited deposition of excess Sr2+ as compared to Mg2+ ions. We conclude that although the sea urchins would be affected in future high CO2 waters, at present they are not at risk even during the south‐west monsoon when low pH waters reside on the shelf. [ABSTRACT FROM AUTHOR]

The effects of increasing soya bean lecithin (SL) levels (0%, 2% and 4% of diet dry matter, DM) at two fish oil (FO) levels (0% and 3% DM) on gonad index, colour and biochemical composition of Strongylocentrotus purpuratus were evaluated using a 3 × 2 factorial design with six iso‐nitrogenous formulated diets. All diets generated an increase in gonad index of more than 9%. Dietary FO had a positive effect on diet digestibility and accumulation of proteins in the gonad. Soy lecithin did not affect gonad composition, but improved its coloration, decreased gonad feed conversion ratio and increased gonad protein efficiency. There was a clear effect of diets on sea urchins gonad protein, ash and fatty acid content, in particular, decreasing the n‐3/n‐6 ratio associated with a decrease in 20:5n‐3 when SL levels increased. Nevertheless, 22:6n‐3 levels increased by week 12 in all treatments, and diets with SL increased the content of 20:4n‐6 in gonads. A decrease in bitter‐tasting amino acids such as histidine, cysteine, valine and methionine was observed in all treatments with a concomitant increase in isoleucine levels. We recommend using a diet containing 3% of FO and 2% of SL to increase food consumption, diet digestibility, improving marketable gonad colour and an increasing gonad n‐6 fatty acids and C22:6n‐3. In addition, the present study paves the way for future research in the use of FO and SL as an additive in diets for S. purpuratus towards the goal of increasing gonad size and nutritional quality. [ABSTRACT FROM AUTHOR]

Surveys of larval diversity consistently increase biodiversity estimates when applied to poorly documented groups of marine invertebrates such as phoronids and hemichordates. However, it remains to be seen how helpful this approach is for detecting unsampled species in well‐studied groups. Echinoids represent a large, robust, well‐studied macrofauna, with low diversity and low incidence of cryptic species, making them an ideal test case for the efficacy of larval barcoding to discover diversity in such groups. We developed a reference dataset of DNA barcodes for the shallow‐water adult echinoids from both coasts of Panama and compared them to DNA sequences obtained from larvae collected primarily on the Caribbean coast of Panama. We sequenced mitochondrial cytochrome c oxidase subunit I (COI) for 43 species of adult sea urchins to expand the number and coverage of sequences available in GenBank. Sequences were successfully obtained for COI and 16S ribosomal DNA from 272 larvae and assigned to 17 operational taxonomic units (OTUs): 4 from the Pacific coast of Panama, where larvae were not sampled as intensively, and 13 from the Caribbean coast. Of these 17 OTUs, 13 were identified from comparisons with our adult sequences and belonged to species well documented in these regions. Another larva was identified from comparisons with unpublished sequences in the Barcode of Life Database (BOLD) as belonging to Pseudoboletia, a genus scarcely known in the Caribbean and previously unreported in Panama. Three OTUs remained unidentified. Based on larval morphology, at least two of these OTUs appeared to be spatangoids, which are difficult to collect and whose presence often goes undetected in standard surveys of benthic diversity. Despite its ability to capture unanticipated diversity, larval sampling failed to collect some species that are locally common along the Caribbean coast of Panama, such as Leodia sexiesperforata, Diadema antillarum, and Clypeaster rosaceus. [ABSTRACT FROM AUTHOR]

Sea urchin (Mesocentrotus nudus) is a major marine resource of Sanriku off the Pacific Coast, Japan, that includes Aomori, Iwate, and Miyagi Prefectures. Using six microsatellites and three mitochondrial DNA regions, we aimed to characterize genetic diversity of M. nudus before and after the 2011 Tohoku earthquake in Sanriku's Touni and Okirai Bays. Although mass death during the Tohoku disaster likely reduced genetic diversity in M. nudus populations, we did not find significant genetic differentiation spatially (between the two bays) or temporally (pre‐ and post‐earthquake). Our data also suggest that M. nudus in Sanriku experienced a population expansion approximately 19–9 thousand years ago, during the long‐lasting, stable, and warm environment after the Last Glacial Maximum (LGM). We conclude that these M. nudus populations maintained their genetic structure throughout multiple disastrous tsunamis over the past several millennia; thus, they were also able to maintain their natural genetic structure and diversity after the 2011 earthquake. [ABSTRACT FROM AUTHOR]

Aim: The Atlanto‐Mediterranean edible purple sea urchin, Paracentrotus lividus, is a commercially exploited keystone species in benthic communities. Its browsing activity can deeply modify the littoral landscape, and changes in its abundance are of major conservation concern. This species is facing nowadays contrasting anthropogenic pressures linked to predator release, exploitation and sea warming. Management of this key species requires knowledge of its genetic structure, connectivity and local adaptation. Our goal was to assess the current global status of the species under a genomic perspective. Location: Atlanto‐Mediterranean shores from Morocco and France to Turkey. Methods: We used genotyping by sequencing (GBS) of 241 individuals belonging to 11 populations spanning the known range of distribution of the species. We obtained 3,348 loci for population genomics and outlier analyses. Results: We identified significant genetic structure and a gradient matching the longitudinal position of the localities. A hierarchical analysis revealed two main clusters (Atlantic and Mediterranean) and subtler patterns of differentiation within them. Candidate markers for selection identified between and within these two main clusters were mostly different, likely indicating different selective pressures. Adaptation to maximum salinity and maximum temperature appeared as an important driver of the transition between Atlantic and Mediterranean basins. Other stressors, such as minimum temperature or range of temperature, seem to define the structuring within the Mediterranean. Main conclusions: Our study shows the potential of hierarchical analyses on population genomics to detect fine‐scale genetic structure and adaptation signatures in marine species with long dispersal capabilities. Although genetic interchange occurs widely in Paracentrotus lividus, the species is sensitive to dispersal barriers, displays isolation by distance and faces local selective pressures associated to environmental conditions, all of which can render it more vulnerable than previously thought. [ABSTRACT FROM AUTHOR]

It is now 50 years since Lewis Wolpert published the paper in which he set out the concept of Positional Information to explain how spatial patterns of cellular differentiation are generated. This concept has provided a universal model for pattern formation in embryonic development and regeneration and become part of the fabric of the field of developmental biology. Here I outline how Wolpert devised the concept of Positional Information and describe landmark studies from his lab investigating how Positional Information is specified in the developing chick limb. Key Findings: Outline how Wolpert came up with the concept of Positional Information.Summarise the key findings of Wolperts landmark 1969 paper.Outline the key studies from the Wolpert Lab demonstrating how Positional Information patterns the developing chick limb.Outline how the 1969 paper underpins and influences our understanding of developmental biology today.Detail the key Personnel in a Wolpert Lab Family Tree. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate how stable carbon (C) and nitrogen (N) isotope analysis can be used to estimate the allocation of specific dietary ingredients, incorporated into four artificially formulated feeds supplemented with varying amounts of dried seaweed Ulva armoricana (0, 50, 150 and 200 g/kg), to the production of gonads by Tripneustes gratilla over a 20‐week growth trial. Results indicate that U. armoricana is an important dietary ingredient for gonad production, accounting for an average of 37.33 ± 1.03% of the isotopic signal recorded for gonads at the end of the growth trial. This is significantly more than fish meal and soya, which only contributed an average of 11.40 ± 1.81 and 3.80 ± 0.09%, respectively, of the isotopic signal of the gonads. Maize and wheat each account for almost 25% of all the dietary ingredients used to formulate the feeds, but their relative contribution to gonad production only averaged 8.55 ± 0.58 and 3.80 ± 0.05%, respectively, among the diets. This indicates that, at least for gonad development, these ingredients may not be required at such high levels. These findings support previous data on the importance of Ulva in abalone and urchin diets, and demonstrate the value of stable isotope analysis for assessing the contribution of specific dietary ingredients in new feed formulations, particularly where growth of specific tissues is being investigated. [ABSTRACT FROM AUTHOR]

Background: Embryonic cells and cancer cells share various cellular characteristics important for their functions. It has been thus proposed that similar mechanisms of regulation may be present in these otherwise disparate cell types. Results: To explore how regulative embryonic cells are fundamentally different from cancerous cells, we report here that a fine balance of a tumor suppressor protein Retinoblastoma1 (Rb1) and a germline factor Vasa are important for proper cell proliferation and differentiation of the somatic cells during embryogenesis of the sea urchin. Rb1 knockdown blocked embryonic development and induced Vasa accumulation in the entire embryo, while its overexpression resulted in a smaller‐sized embryo with differentiated body structures. These results suggest that a titrated level of Rb1 protein may be essential for a proper balance of cell proliferation and differentiation during development. Vasa knockdown or overexpression, on the other hand, reduced or increased Rb1 protein expression, respectively. Conclusions: Taken together, it appears that Vasa protein positively regulates Rb1 protein while Rb1 protein negatively regulates Vasa protein, balancing the act of these two antagonistic molecules in somatic cells. This mechanism may provide a fine control of cell proliferation and differentiation, which is essential for regulative embryonic development. Key Findings: A tumor suppressor Rb1 is important for proper embryonic development of the sea urchin.Rb1 overexpression incompletely progresses and its knockdown compromises embryonic development.Rb1 knockdown results in excessive Vasa accumulation in the entire embryo.A fine balance of Rb1 and Vasa is critical for regulative embryonic development. [ABSTRACT FROM AUTHOR]

Ocean warming (OW) and acidification (OA) are intensively investigated as they pose major threats to marine organism. However, little effort is dedicated to another collateral climate change stressor, the increased frequency, and intensity of storm events, here referred to as intensified hydrodynamics. A 2‐month experiment was performed to identify how OW and OA (temperature: 21°C; pHT: 7.7, 7.4; control: 17°C‐pHT7.9) affect the resistance to hydrodynamics in the sea urchin Paracentrotus lividus using an integrative approach that includes physiology, biomechanics, and behavior. Biomechanics was studied under both no‐flow condition at the tube foot (TF) scale and flow condition at the individual scale. For the former, TF disk adhesive properties (attachment strength, tenacity) and TF stem mechanical properties (breaking force, extensibility, tensile strength, stiffness, toughness) were evaluated. For the latter, resistance to flow was addressed as the flow velocity at which individuals detached. Under near‐ and far‐future OW and OA, individuals fully balanced their acid‐base status, but skeletal growth was halved. TF adhesive properties were not affected by treatments. Compared to the control, mechanical properties were in general improved under pHT7.7 while in the extreme treatment (21°C‐pHT7.4) breaking force was diminished. Three behavioral strategies were implemented by sea urchins and acted together to cope with flow: improving TF attachment, streamlining, and escaping. Behavioral responses varied according to treatment and flow velocity. For instance, individuals at 21°C‐pHT7.4 increased the density of attached TF at slow flows or controlled TF detachment at fast flows to compensate for weakened TF mechanical properties. They also showed an absence of streamlining favoring an escaping behavior as they ventured in a riskier faster movement at slow flows. At faster flows, the effects of OW and OA were detrimental causing earlier dislodgment. These plastic behaviors reflect a potential scope for acclimation in the field, where this species already experiences diel temperature and pH fluctuations. [ABSTRACT FROM AUTHOR]

To investigate the effects of family, stocking density, and their interaction on mortality, growth rate, and size dispersal in the sea urchin Strongylocentrotus intermedius, 1,440 juveniles from six full‐sib families were exposed to three stocking densities, that is, low stocking density (LD), middle stocking density (MD), and high stocking density (HD), and reared for 10 months in sea‐based suspended cages. The results demonstrated significant family effects on cumulative mortality rate (CMR); specific growth rate for test diameter (SGR for TD); specific growth rate for body weight (SGR for BW); coefficient of variation for body weight at the 10th month (CV for BW10); and significant stocking density effects on SGR for TD, SGR for BW, and CV for BW10. Statistically significant family by stocking density interaction was only found in SGR for TD. A certain degree of family‐ranking inversions occurred in SGR for TD. The present study provides evidence for the existence of family by stocking density interaction on the growth rate of test diameter in the family selection for S. intermedius. More attention should be paid to this interaction effect to select correct parents in S. intermedius. [ABSTRACT FROM AUTHOR]

The development of sustainable methods for sea urchin juvenile production is currently constrained by high mortality rates during larval growth and the high costs of larval rearing systems management. With the aim of developing a method for the production of juveniles of the purple sea urchin Paracentrotus lividus in a medium‐scale recirculating system, the present study focused on the effects of high stocking densities on larval growth. Plutei larvae were reared at three different densities (up to 7 ind/ml) in a semi‐static culture system. Larval survival and metamorphosis success were evaluated in order to identify the most effective density range. The highest metamorphosis rates (80%–95%) were obtained at 4 and 7 larvae/ml. These results are comparable with (and in some cases higher than) those reported for the same species at much lower larval densities. In conclusion, the rearing conditions tested here show for the first time that a significantly higher (4 ind/ml) stocking density than those of traditional P. lividus rearing methods (based on large volumes and low densities) can be adopted, thus supporting the feasibility of an increase in the final output of competent larvae with no increase in rearing volumes. [ABSTRACT FROM AUTHOR]

Sea urchins are used as a model organism for research on developmental biology and gene regulatory networks during early development. Gene knockdown by microinjection of morpholino antisense oligonucleotide (MASO) has been used to analyze gene function in early sea urchin embryos. However, as the effect of MASO is not long lasting, it is impossible to perturb genes expressed during late development by MASO. Recent advances in genome editing technologies have enabled gene modification in various organisms. We previously reported genome editing in the sea urchin Hemicentrotus pulcherrimus using zinc‐finger nuclease (ZFN) and transcription activator‐like effector nuclease (TALEN); however, the efficiencies of these technologies were not satisfactory. Here, we applied clustered regularly interspaced short palindromic repeat (CRISPR)‐CRISPR‐associated nuclease 9 (Cas9) technology to knock out the Pks1 gene in H. pulcherrimus. When sgRNAs targeting Pks1, which is required for the biosynthesis of larval pigment, were microinjected into fertilized eggs with SpCas9 mRNA, high‐efficiency mutagenesis was achieved within 24 hr post fertilization and SpCas9/sgRNA‐injected pluteus larvae had an albino phenotype. One of the sgRNAs yielded 100% mutagenesis efficiency, and no off‐target effect was detected. In addition, the albino phenotype was maintained in juvenile sea urchins after metamorphosis, and the knockout sea urchins survived for at least one year and grew to albino adult sea urchins. These findings suggest that knockout adult sea urchins were successfully established and the CRISPR‐Cas9 system is a feasible method for analyzing gene functions from late developmental to adult stage. [ABSTRACT FROM AUTHOR]

In this study, the effects of three diets were investigated to enhance Paracentrotus lividus production for commercial purposes. P. lividus were fed ad libitum for 80 days with: diet A—fresh Codium tomentosum Stackhouse, 1797; diet B—formulated using a jellified mix of macroalgae and vegetables, including C. tomentosum (20%), Coralina sp. Linnaeus, 1758 (17%), cabbage Brassica oleracea var. capitata Linnaeus, 1753 (30%), carrot Daucus carota Linnaeus, 1753 (30%) and agar (3%) as a gelling agent. Diet C consisted of maize Zea mays Linnaeus, 1753 (56%) and New Zealand spinach Tetragonia tetragonoides (Pallas, 1781) Kuntze, 1891 (44%). Their effects on the gonadal and somatic growths, gonadosomatic index (GI) and gametogenesis were evaluated, as well as on the total lipid content and fatty acid composition of sea urchin's gonads. Diet A provided high values of eicosapentaenoic acid (EPA). Gonads of sea urchins fed with diet A were found mostly in growth and maturation stages of gametogenesis and showed the lowest lipid content. Sea urchins fed with diet B presented their gonads in the reabsorption stage and had the highest values of omega‐3 polyunsaturated fatty acids (PUFAs). Sea urchins fed with diet C were in the early stages of gametogenesis and had the highest values of lipid content, plus omega‐6 PUFAs. Once as an ingredient in a balanced mix with vegetables, C. tomentosum can be a key factor to the development of new promising high‐quality and low‐cost feed for P. lividus roe enhancement. [ABSTRACT FROM AUTHOR]

Sea urchin roe is highly appreciated worldwide as a gourmet product comparable to caviar. Research in echinoculture mainly focus on the production of high‐quality roe which stands for large golden orange to yellow gonads with a distinct, sweet ocean taste known as uni. The scientific approaches to manipulate roe quality are diverse in terms of targeted species and manipulated factors as nutrition, environmental and husbandry conditions. In this study, a meta‐analysis approach was applied to systematically review the research conducted between 2000 and 2017 aiming to enhance the sea urchin roe quality. The 48 studies selected and analysed here show that those targeting the growth of gonads were successful, independently of the selected species, the rearing system adopted, or the diet or nutrient tested. In contrast, most trials focusing on colour manipulation resulted in roe colour similar to the control group (sea urchins fed with algae). Only six studies aiming to enhance roe taste were selected but described inconclusive results. In conclusion, while the production of large gonads seems easily achievable, the enhancement of its colour and taste is still a challenge. [ABSTRACT FROM AUTHOR]

Sea urchins produce high‐energy, membrane‐bound fecal pellets that contain residual nutrients and large quantities of microbiota. These egesta are readily consumed by the shrimp, Litopenaeus vannamei. Egesta of the sea urchin, Lytechinus variegatus, were evaluated as a feed supplement or total replacement for a commercial shrimp diet. Shrimp were stocked at 0.49 g ± 0.06 g initial body weight and housed individually in 2.8‐L tanks in a commercial recirculating zebrafish system. Shrimp were assigned to one of six diets: commercial shrimp feed, reference sea urchin feed, collected dried sea urchin egesta, collected wet sea urchin egesta, half ration of shrimp feed and half collected wet sea urchin egesta, and egesta naturally produced by two sea urchins in polyculture. Equivalent dry matter amounts of each diet were proffered to shrimp in each treatment twice daily, except for those that had complete access to natural egesta excreted by sea urchins in polyculture. Sea urchins were proffered a reference sea urchin feed at 2% body weight daily. After 27 days, shrimp proffered collected dried or wet egesta did not differ significantly in percent weight gain and showed the lowest weight gain. The percent weight gain of shrimp fed the commercial shrimp diet did not differ significantly from that of the shrimp fed half commercial shrimp diet and half egesta. The highest weight gain was recorded for those shrimp that consumed the untouched egesta produced by sea urchins in polyculture. These data suggest that consumed egesta have noteworthy nutritional value and therefore would be beneficial to the culture of extractive species in an integrated multitrophic aquaculture system. [ABSTRACT FROM AUTHOR]

We present a simple, quick, and viable way to produce hydroxyapatite (HA) from a waste by‐product of the sea food industry, this was achieved by submitting the exoskeleton of the purple sea urchin Strongylocentrotus purpuratus through a chemical reaction with H3PO4 at 3 different times (3, 18, and 36 hours) with constant stirring at 35‐40°C. The characterization of the materials was made by several techniques (FTIR, XRD, SEM‐EDS, and TEM).The FTIR results confirmed the presence of the HA characteristic functional groups OH, PO4, and CO3, the XRD characterization showed that the synthesis of calcium phosphates such as brushite and HA was achieved by confirming the presence of its characteristic peaks, also the EDS analysis confirmed the expected HA Ca/P atomic ratio of 1.67. This work shows that we can take advantage from raw materials derived from processing sea food by giving it an added value for the biomedical industry. [ABSTRACT FROM AUTHOR]