Search

Ecological communities can be stable over multiple generations, or rapidly shift into structurally and functionally different configurations. In kelp forest ecosystems, overgrazing by sea urchins can abruptly shift forests into alternative states that are void of macroalgae and primarily dominated by actively grazing sea urchins. Beginning in 2014, a sea urchin outbreak along the central coast of California resulted in a patchy mosaic of remnant forests interspersed with sea urchin barrens. In this study, we used a 14-year subtidal monitoring dataset of invertebrates, algae, and fishes to explore changes in community structure associated with the loss of forests. We found that the spatial mosaic of barrens and forests resulted in a region-wide shift in community structure. However, the magnitude of kelp forest loss and taxonomic-level consequences were spatially heterogeneous. Taxonomic diversity declined across the region, but there were no declines in richness for any group, suggesting compositional redistribution. Baseline ecological and environmental conditions, and sea urchin behaviour, explained the persistence of forests through multiple stressors. These results indicate that spatial heterogeneity in preexisting ecological and environmental conditions can explain patterns of community change.

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]

A profound collaboration between the germline and somatic cells of an organism is the creation of a functional gonad. Here we establish a foundation for studying molecular gonadogenesis in the sea urchin by use of RNA-seq, quantitative mRNA measurements, and in-situ hybridizations throughout the life cycle of the variegated sea urchin, Lytechinus variegatus (Lv). We found through three distinct analyses that the ovary and testis of this echinoderm expresses unique transcripts involved in gametogenesis, and also discovered uncharacterized gene products unique to each gonad. We further developed a pipeline integrating timepoint RNA-seq data throughout development to identify hallmark gene expression in gonads. We found that meiotic and candidate genes involved in sex determination are first expressed surprisingly early during larval growth, and well before metamorphosis. We further discovered that individual larvae express varying amounts of male- or female-hallmarks before metamorphosis, including germline, oocyte, sperm, and meiotic related genes. These distinct male- or female-gonad gene profiles may indicate the onset of, and commitment to, development of a bipotential gonad primordium, and may include metabolic differences, supported by the observation that transcripts involved in glycolysis are highly enriched in the ovary compared to the testis. Together these data support a hypothesis that sex determination is initiated prior to metamorphosis in the sea urchin and that the many uncharacterized genes unique to each gonad type characterized herein may reveal unique pathways and mechanisms in echinoderm reproduction. [Display omitted] • Gonads of the sea urchin, Lytechinus variegatus , have distinct transcriptome profiles based on sex. • Expression of sex-specific genes begins well prior to metamorphosis. • Sex specific gene expression includes, but is not limited to, genes involved in gametogenesis. • Male sex-specific profiles emerge earlier in development than the female profile. • Female sex-specific transcripts, including glycolytic enzymes, fluctuate with the reproductive stage of the ovary. [ABSTRACT FROM AUTHOR]

Regulative development, demonstrated by many animal embryos, is the ability to replace missing cells or parts. The underlying molecular mechanism(s) of that ability is not well understood. If sea urchin micromeres (skeletogenic cell progenitors) are removed at the 16-cell stage, early endoderm initiates a sequential switch in cell fates, called transfating. Without micromeres, other mesoderm cells are absent as well, because their specification depends on signaling from micromeres. Most mesoderm cells later return by transfating, but pigment cells do not. Single-cell RNA sequencing, tracked over time, reveals the reprogramming sequence of those replacements. Beginning with an early endoderm specification state, cells progress through endomesoderm, then mesoderm, and finally distinct skeletogenic and blastocoelar cell specification states emerge, but pigment cells do not. Rescue of pigment cells was found to be a consequence of signal timing: if Delta is expressed prior to Nodal, pigment cells return. Thus, transfating operates through a series of gene regulatory state transitions, and reprogramming fails if endogenous negative signals occur prior to positive signals in the reprogramming sequence. [ABSTRACT FROM AUTHOR]

The sea urchin Sculpsitechinus tenuissimus (L. Agassiz & Desor, 1847a) is known to inhabit warm, shallow waters around Japan and has been previously recorded in Tanegashima, Amami Oshima, and the main island of Okinawa; however, it has never been formally recorded in Kumejima until now. In this paper, we present the first known record of S. tenuissimus in Kumejima. [ABSTRACT FROM AUTHOR]

Simple Summary: Glioblastoma is a fatal brain tumor, with recurrence and eventual mortality inevitable despite the current standard of care treatments. The identification of novel therapies capable of extending survival is therefore imperative. In this case series, we describe two cases in which marine nutraceuticals were used in the management of glioblastoma and conferred a survival benefit exceeding the currently recognized median survival time of standard of care treatment. In the subsequent literature review, we describe the mechanisms underlying the anticancer and immunogenic properties of marine nutraceuticals, which may contribute to their demonstrated therapeutic benefit. Introduction: Glioblastoma is a fatal intracranial neoplasm that is refractory to treatment, with inevitable disease recurrence and progression to death. Marine-derived compounds, including those found in nutraceutical products, may provide therapeutic benefit in the setting of glioblastoma. We present two patient cases whose courses demonstrate a compelling role for marine-derived products in the management of glioblastoma. Cases: Case 1 describes a patient with MGMT promoter unmethylated glioblastoma who went on to complete standard of care chemoradiation along with concurrent use of a majority sea cucumber (MSC) blend known as SeaCare® (SeaCare, Torrington, CT, USA). Her survival of over 2 years significantly exceeds the recognized median survival time of glioblastoma. Case 2 describes a patient with a complicated course who experienced dramatic improvement after the initiation of the MSC blend, with an exceptional survival time of over 4 years post-diagnosis. Discussion: The mechanisms of marine-derived products that underlie these dramatic clinical effects are likely multifaceted but may hinge on the modification of the tumor immune microenvironment and suppression of tumorigenic effects. Specifically, the change in tumor-associated macrophages (TAMs) within the tumor microenvironment is central to this complex interplay. Conclusions: Ultimately, the use of marine products in the treatment of glioblastoma may present a novel and promising therapeutic strategy that warrants further investigation. [ABSTRACT FROM AUTHOR]

Growing evidence suggests that metabolic regulation directly influences cellular function and development and thus may be more dynamic than previously expected. In vivo and in real-time analysis of metabolite activities during development is crucial to test this idea directly. In this study, we employ two metabolic biosensors to track the dynamics of pyruvate and oxidative phosphorylation (Oxphos) during the early embryogenesis of the sea urchin. A pyruvate sensor, PyronicSF, shows the signal enrichment on the mitotic apparatus, which is consistent with the localization patterns of the corresponding enzyme, pyruvate kinase (PKM). The addition of pyruvate increases the PyronicSF signal, while PKM knockdown decreases its signal, responding to the pyruvate level in the cell. Similarly, a ratio-metric sensor, Grx-roGFP, that reads the redox potential of the cell responds to DTT and H 2 O 2 , the known reducer and inducer of Oxphos. These observations suggest that these metabolic biosensors faithfully reflect the metabolic status in the cell during embryogenesis. The time-lapse imaging of these biosensors suggests that pyruvate and Oxphos levels change both spatially and temporarily during embryonic development. Pyruvate level is increased first in micromeres compared to other blastomeres at the 16-cell stage and remains high in ectoderm while decreasing in endomesoderm during gastrulation. In contrast, the Oxphos signal first decreases in micromeres at the 16-cell stage, while it increases in the endomesoderm during gastrulation, showing the opposite trend of the pyruvate signal. These results suggest that metabolic regulation is indeed both temporally and spatially dynamic during embryogenesis, and these biosensors are a valuable tool to monitor metabolic activities in real-time in developing embryos. • PKM and pyruvate localize on the spindle and in the nucleus during early embryogenesis of the sea urchin. • Pyruvate is increased in micromeres, while Oxidative phosphorylation is decreased in micromeres. • Pyruvate and Oxidative phosphorylation sensors show an opposite trend of expression dynamics during embryogenesis. • Metabolic biosensors are valuable tools for analyzing in vivo metabolic regulation in developing embryos. [ABSTRACT FROM AUTHOR]

Dicer substrate interfering RNAs (DsiRNAs) destroy targeted transcripts using the RNA-Induced Silencing Complex (RISC) through a process called RNA interference (RNAi). This process is ubiquitous among eukaryotes. Here we report the utility of DsiRNA in embryos of the sea urchin Lytechinus variegatus (Lv). Specific knockdowns phenocopy known morpholino and inhibitor knockdowns, and DsiRNA offers a useful alternative to morpholinos. Methods are described for the design of specific DsiRNAs that lead to destruction of targeted mRNA. DsiRNAs directed against pks1 , an enzyme necessary for pigment production, show how successful DsiRNA perturbations are monitored by RNA in situ analysis and by qPCR to determine relative destruction of targeted mRNA. DsiRNA-based knockdowns phenocopy morpholino- and drug-based inhibition of nodal and lefty. Other knockdowns demonstrate that the RISC operates early in development as well as on genes that are first transcribed hours after gastrulation is completed. Thus, DsiRNAs effectively mediate destruction of targeted mRNA in the sea urchin embryo. The approach offers significant advantages over other widely used methods in the urchin in terms of cost, and ease of procurement, and offers sizeable experimental advantages in terms of ease of handling, injection, and knockdown validation. • DsiRNA provides an RNAi approach for perturbation of sea urchin embryos. • A dilution series of DsiRNA oligos reveals properties of the Nodal gradient in establishing the Dorsal-Ventral axis. [ABSTRACT FROM AUTHOR]

Relatively well-preserved echinoids from Palaeozoic strata are exceptionally rare fossils. New fossil finds can thus have an important impact on our understanding of the morphology, phylogenetic relationships and history of diversification of early sea urchins. The Devonian strata of Germany have long been known to contain echinoids, predominantly through the relatively abundant record of disarticulated plates and spines. In contrast, only select articulated or semi-articulated specimens are recorded. We herein describe new specimens from the Middle and Late Devonian belonging to two Palaeozoic echinoid taxa, Rhenechinus hopstaetteri and Lepidocentrus eifelianus. These specimens are amongst the most-complete known for these two taxa, and provide novel insight into their morphology and stratigraphic range. Additionally, the record of Rhenechinus is the youngest occurrence of an echinocystitid echinoid in the fossil record, indicating that this family ranged from the Silurian (Aeronian or Telychian) to at least the Middle Devonian (Givetian), prior to going extinct. The morphological details provided by the new specimen of L. eifelianus highlights similarities between this species and other Devonian echinoids known from elsewhere in Europe and North America, and suggest that the lepidocentrids were widely dispersed and abundant during the Devonian. [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 Antarctic sea urchin Sterechinus neumayeri (Echinoida; Echinidae) is routinely used as a model organism for Antarctic biology. Here, we present a high-quality genome of S. neumayeri. This chromosomal-level assembly was generated using PacBio long-read sequencing and Hi-C chromatin conformation capture sequencing. This 885.3-Mb assembly exhibits high contiguity with a scaffold length N50 of 36.7 Mb assembled into 20 chromosomal length scaffolds. These putative chromosomes exhibit a high degree of synteny compared to other sea urchin models. We used transcript evidence gene modeling combined with sequence homology to identify 21,638 gene models that capture 97.4% of BUSCO orthologs. Among these, we were able to identify and annotate conserved developmental gene regulatory network orthologs, positioning S. neumayeri as a tractable model for comparative studies on evolution and development. [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]

It is essential to understand the spatial distribution of a target species for effective stock management, particularly in the case of less mobile rock-dwelling species such as sea urchins. However, sea urchins exhibit an aggregated distribution within fishing grounds, thereby necessitating diving surveys at multiple sites to elucidate their spatial distribution at a fine scale. In Mikuni, Sakai City, Fukui Prefecture, Japan, female divers are well-acquainted with the underwater landscape and can determine the sea urchin catch per fishing ground. They also conduct voluntary fishery management for the sea urchin. Therefore, we enlisted female divers to report the sea urchin Hemicentrotus pulcherrimus catch during the 2020–2022 period and subsequently visualized the spatial distribution of these catches and estimated initial abundance using the Leslie method according to the fishing ground. The catch per unit effort did not decrease although the cumulative catch increased in many fishing grounds. This was because divers sensibly perceived the status of sea urchin stocks at each fishing ground through the dive fishery and they voluntarily controlled their fishing efforts to prevent stock depletion. Our results highlight that the catch data are often used for stock estimation but are influenced by fishermen's management of the fishery. [ABSTRACT FROM AUTHOR]

Gametogenesis and the accumulation of nutrients such as proteins progress in sea urchin gonads during their growth. In vertebrate species, these physiological mechanisms are regulated by nuclear receptors. Although it has been estimated that there are several dozen nuclear receptor homologs in the genome of the purple sea urchin Strongylocentrotus purpuratus their functions and which ones are expressed in the gonads remain unclear. Here, we investigated the expression of nuclear receptor genes in early gametogenesis and the dynamics of their expression during germ cell formation in the northern sea urchin Mesocentrotus nudus. First, we identified the vasa sequence in M. nudus, and quantitative PCR of vasa and histological analysis revealed that germline cells were undergoing proliferation and differentiation in the growing gonads. During this period, 23 nuclear receptor genes were expressed in the male and female gonads. The expression levels of five nuclear receptor genes (eip78c, trβ, bar, rxrγ, and ftz-f1β) were found to be increased during gonadal growth in both sexes, suggesting that these nuclear receptors exert certain functions during the growth period of the gonads. Our results provide the first comprehensive experimental data on nuclear receptors for a species of sea urchin. [ABSTRACT FROM AUTHOR]

Background: Understanding the dynamics of the gut microbiota in sea urchins is crucial for comprehending the ecological balance in marine ecosystems. The gut microbiota plays a vital role in nutrient metabolism, immune system modulation, and pathogen protection. The microbial composition and dynamics of naturally occurring sea urchin Tripneustes ventricosus have yet to be thoroughly investigated. We hypothesized the gut microbiota of T. ventricosus in the Caribbean, varies across life stages and seasons. Methods: Thirty-six naturally occurring large individuals and six small individuals (42 animals) were collected from shallow waters on the northeastern coast of Puerto Rico in February and August of 2019. The fecal pellet's microbiota was characterized by sequencing V4 region of the 16S rRNA gene. Results: We found significant differences in the composition of fecal pellet microbiota between seasons and life stages. Phylum Bacteroidota had greater relative abundance in August, while Firmicutes was more dominant in February. Propionigenium and Roseimarinus had greater relative abundance in August, while Candidatus Hepatoplasma, and Kistimonas had greater relative abundance in February. Differences in the gut digest microbiota were not found between small and large urchins, but small urchins displayed a slightly higher diversity and dominance of Bacteroidota and Proteobacteria, while large urchins exhibited a greater relative abundance of Fusobacteria and Desulfobacterota. However, the genera Ferrominas and Propionigenium counts were significantly lower in small individuals. Discussion: This is the first report for this species in the Caribbean region and adds to our comprehension of the microbiota of the white sea urchin across collection periods and size classes, highlighting the dynamic nature of the gut microbiota. [ABSTRACT FROM AUTHOR]

We have previously shown that Golgi stacks and recycling endosomes (REs) exist as Golgi/RE units in sea urchin embryos. In this study, we showed that Golgi/RE units were scattered throughout the cytoplasm at early developmental stages but gathered to form a “Golgi ring” surrounding the centric REs at the blastula stage. This change in the cell-wide arrangement of Golgi/RE units coincided with a dramatic change in microtubule organization from a randomly oriented cortical pattern to radial arrays under the apical plasma membrane. A single gigantic Golgi apparatus surrounding centric RE is clearly associated with the center of the radial microtubule arrays. Furthermore, we found that in some animal species belonging to different clades, Golgi stacks lack lateral connections but are likely centralized by microtubule motors. These results suggest that Golgi centralization depends on the organization of the microtubule array in addition to the lateral linking between Golgi stacks. Key words: Golgi stack, recycling endosome, Golgi-ribbon, microtubule, cilium, sea urchin, ascidian

Abstract Background Echinometra mathaei (family Echinometridae), is one of the sea urchins widely distributed on the Egyptian coasts in the Red Sea. This organism contains edible and non-edible parts. The present study was carried out to analyze and identify the metabolites present in the non-edible parts (Aristotle's lantern and viscera) using LC/MS. Also, the cytotoxic activity on Vero cell line and antiviral activity against herpes simplex virus type 1 were evaluated using MTT colorimetric assay. Results Chemical profiling of the crude extracts of Aristotle's lantern and viscera using LC/MS indicated the presence of 51 and 59 compounds, respectively. The main metabolites present in both non-edible parts were phospholipids, amino acids, peptides, fatty acids and glycerol derivatives. However, the characteristic difference was the presence of carotenoid pigments only in viscera. The crude extract of Aristotle's lantern and viscera showed no cytotoxic activity on Vero cell line and significant antiviral activity against herpes simplex virus with an IC50 value equal to 115.48 ± 1.20 and 122.4 ± 0.50 µg/mL, respectively. Conclusions In the present study, the crude extracts of the non-edible parts of E. mathaei were analyzed using LC.MS.MS.QTOF and indicated the existence of 110 chemical compounds, with significant antiviral activity against HSV-1 and no cytotoxic activity. The diversity of the identified compounds with two main categories of compounds, phospholipids and peptides, may contribute to the antiviral activity of Aristotle's lantern and viscera. Additionally, this research focused on clarification of nutritive, pharmaceutical and economic values of these parts. As future prospects, further studies are required to isolate the metabolites and assess the detailed mechanism of antiviral activity via in vitro, in vivo and in silico studies.

Our knowledge of the assembly and dynamics of the cytokinetic contractile ring (CR) in animal cells remains incomplete. We have previously used super-resolution light microscopy and platinum replica electron microscopy to elucidate the ultrastructural organization of the CR in first division sea urchin embryos. To date, our studies indicate that the CR initiates as an equatorial band of clusters containing myosin II, actin, septin and anillin, which then congress over time into patches which coalesce into a linear array characteristic of mature CRs. In the present study, we applied super-resolution interferometric photoactivated localization microscopy to confirm the existence of septin filament-like structures in the developing CR, demonstrate the close associations between septin2, anillin, and myosin II in the CR, as well as to show that septin2 appears consistently submembranous, whereas anillin is more widely distributed in the early CR. We also provide evidence that the major actin cross-linking protein α-actinin only associates with the linearized, late-stage CR and not with the early CR clusters, providing further support to the idea that α-actinin associates with actomyosin structures under tension and can serve as a counterbalance. In addition, we show that inhibition of actomyosin contraction does not stop the assembly of the early CR clusters but does arrest the progression of these structures to the aligned arrays required for functional cytokinesis. Taken together our results reinforce and extend our model for a cluster to patch to linear structural progression of the CR in sea urchin embryos and highlight the evolutionary relationships with cytokinesis in fission yeast. [ABSTRACT FROM AUTHOR]

Our knowledge of the assembly and dynamics of the cytokinetic contractile ring (CR) in animal cells remains incomplete. We have previously used superresolution light microscopy and platinum replica electron microscopy to elucidate the ultrastructural organization of the CR in first division sea urchin embryos. To date, our studies indicate that the CR initiates as an equatorial band of clusters containing myosin II, actin, septin and anillin, which then congress over time into patches which coalesce into a linear array characteristic of mature CRs. In the present study, we applied super-resolution interferometric photoactivated localization microscopy to confirm the existence of septin filament-like structures in the developing CR, demonstrate the close associations between septin2, anillin, and myosin II in the CR, as well as to show that septin2 appears consistently submembranous, whereas anillin is more widely distributed in the early CR. We also provide evidence that the major actin cross-linking protein a-actinin only associates with the linearized, late-stage CR and not with the early CR clusters, providing further support to the idea that a-actinin associates with actomyosin structures under tension and can serve as a counterbalance. In addition, we show that inhibition of actomyosin contraction does not stop the assembly of the early CR clusters but does arrest the progression of these structures to the aligned arrays required for functional cytokinesis. Taken together our results reinforce and extend our model for a cluster to patch to linear structural progression of the CR in sea urchin embryos and highlight the evolutionary relationships with cytokinesis in fission yeast. [ABSTRACT FROM AUTHOR]

The development of the sea urchin larval body plan is well understood from extensive studies of embryonic patterning. However, fewer studies have investigated the late larval stages during which the unique pentaradial adult body plan develops. Previous work on late larval development highlights major tissue changes leading up to metamorphosis, but the location of specific cell types during juvenile development is less understood. Here, we improve on technical limitations by applying highly sensitive hybridization chain reaction fluorescent in situ hybridization (HCR-FISH) to the fast-developing and transparent sea urchin Lytechinus pictus , with a focus on skeletogenic cells. First, we show that HCR-FISH can be used in L. pictus to precisely localize skeletogenic cells in the rudiment. In doing so, we provide a detailed staging scheme for the appearance of skeletogenic cells around the rudiment prior to and during biomineralization and show that many skeletogenic cells unassociated with larval rods localize outside of the rudiment prior to localizing inside. Second, we show that downstream biomineralization genes have similar expression patterns during larval and juvenile skeletogenesis, suggesting some conservation of skeletogenic mechanisms during development between stages. Third, we find co-expression of blastocoelar and skeletogenic cell markers around juvenile skeleton located outside of the rudiment, which is consistent with data showing that cells from the non-skeletogenic mesoderm embryonic lineage contribute to the juvenile skeletogenic cell lineage. This work sets the foundation for subsequent studies of other cell types in the late larva of L. pictus to better understand juvenile body plan development, patterning, and evolution. [Display omitted] • Indirect development in sea urchins has made juvenile development challenging to study. • Juvenile sea urchin development can be better understood by applying HCR-FISH. • Skeletogenic gene expression patterns are similar during larval and juvenile development. • Blastocoelar genes are sometimes expressed in presumptive juvenile skeletogenic cells. [ABSTRACT FROM AUTHOR]

The effect of a fraction of phlorethol (CcPh), one of the polyphenolic compounds isolated from the brown alga Costaria costata (Turn.) Saund (Laminariales), on gametes and embryogenesis of the sea urchin Strongylocentrotus intermedius (A. Agassiz, 1864) was studied. Using a model of developing sea urchin embryos, it was shown that phlorethol at concentrations of ≤700 μg/mL did not exert a cytotoxic effect on early developmental stages (from the zygote to the 16-celled stage blastomere). The embryotoxic effect of phlorethol that caused the death of 50% of the embryos was expressed in a concentration (I) range of 50 < I ≤ 100 μg/mL only after 24 h of incubation, in the blastula stage. When exposed to concentrations greater than 100 μg/mL, embryos that survived to the blastula stage did not develop further and died after 36 h of incubation. Under the effect of phlorethol, the fertilizing capacity of sea urchin spermatozoa and oocytes decreased. The concentration of phlorethol that inhibited fertilization by 50% (IC50) when acting on sperm was 1.28 ± 0.38 μg/mL and when acting on oocytes was 3.83 ± 0.82 μg/mL. Thus, phlorethol reduces the fertilizing capacity of sea urchin gametes at concentrations much lower than embryotoxic concentrations and can potentially find practical application as part of new contraceptive drugs for mammals and humans. [ABSTRACT FROM AUTHOR]

Bacterial assemblages associated with sea urchin are critical to their physiology and ecology within marine ecosystems. In this study, we characterized the bacterial communities in wild sea urchin Anthocidaris crassispina captured in Daya Bay, South China Sea. A total of 363 amplicon sequence variants belonging to nine phyla and 141 genera were classified from intestine, body surface, and surrounding seawater samples. Proteobacteria, Firmicutes, and Bacteroidetes were the dominant bacteria phyla found in this study. A network analysis of bacterial interspecies interactions revealed varying complexity, stability, connectivity, and relationship patterns across the samples, with the most intricate network observed in the surrounding seawater. Metagenomic predictions highlighted the distinct bacterial metabolic pathways, with significant differences between intestine and seawater samples. Notably, pathways associated with polysaccharide degradation, including chitin derivatives, starch, and CoM biosynthesis, were markedly abundant, underscoring the gut microbiota's key role in digesting algae. In addition, other metabolic pathways in intestine samples were linked to immune response regulation of sea urchins. Overall, this study provides a comprehensive overview of the bacterial community structure and potential functional roles in A. crassispina. [ABSTRACT FROM AUTHOR]

The Persian Gulf is a semi-closed inland sea with specific ecological conditions, and the level of oil pollution in it exceeds the global average acceptable for the marine environment. Echinoderms, due to their benthic nature, are more exposed to sediment pollution. This study was conducted in the intertidal zones of Bushehr province, including the shores of Shaghab, Owli, Shirino, Nay-Band, the T-pier and the Northern Khark Island, to determine the level of contamination in sediments and the tissue of the sea urchin Echinometra mathaei. Sampling was carried out in two seasons, winter and summer (2014-2015). In the laboratory, the samples were analyzed for the type and concentration of polycyclic aromatic hydrocarbons (PAHs) using chromatography and GC-MS. The highest concentration of PAHs in the sediments at the T pier in Khark was found to be naphthalene (913.7ng/g dry weight) in the winter, while the highest concentration of PAHs in the tissue was measured as phenanthrene (371.5ng/g dry weight) in the summer. No significant difference was observed between the levels of PAHs in sediments and tissues (P>0.05). The trend of PAH accumulation in sediments and tissues was increasing. The level of PAHs in sediments across all study areas (3059- 441ng/g) was higher than the global standards set for sediments (197µg/kg), indicating greater pollution in the examined areas. A comparison of pollution accumulation in the tissues of the sea urchin with other aquatic species revealed higher PAH levels in the tissues of benthic species. This finding is due to the habitat and feeding type of these organisms, highlighting the importance of this species and the need for environmental toxicological studies on it. [ABSTRACT FROM AUTHOR]

Climate change is causing increased coastal freshening in Antarctica, leading to reduced salinity. For Antarctica's endemic echinoderms, adapted to the stable polar environment, the impact of rapid reductions in coastal salinity on physiology and behaviour is currently unknown. Six common Antarctic echinoderms (the sea urchin Sterechinus neumayeri; the sea star Odontaster validus; the brittle star Ophionotus victoriae; and three sea cucumbers Cucumaria georgiana, Echinopsolus charcoti and Heterocucumis steineni), were directly transferred from ambient salinity (34.5‰) to a range of salinity dilutions (29–9‰) for 24 h. All species showed reduced activity and the establishment of a temporary osmotic gradient between coelomic fluid and external seawater. Most species exhibited a depression in oxygen consumption across tolerated salinities; however, at very low salinities that later resulted in mortality, oxygen consumption increased to levels comparable to those at ambient. Low salinity tolerance varied substantially between species, with O. victoriae being the least tolerant (24 h LC50 (lethal for 50% of animals) = 19.9‰) while E. charcoti and C. georgiana demonstrated the greatest tolerance (24 h LC50 = 11.5‰). These findings demonstrate the species-specific response of Antarctica's endemic echinoderms to short-term hypoosmotic salinity events, providing valuable insight into this phylum's ability to respond to an underreported impact of climate change. [ABSTRACT FROM AUTHOR]

miR-31 is a highly conserved microRNA that plays crucial roles in cell proliferation, migration and differentiation. We discovered that miR-31 and some of its validated targets are enriched on the mitotic spindle of the dividing sea urchin embryo and mammalian cells. Using the sea urchin embryo, we found that miR-31 inhibition led to developmental delay correlated with increased cytoskeletal and chromosomal defects. We identified miR-31 to directly suppress several actin remodeling transcripts, including β-actin, Gelsolin, Rab35 and Fascin. De novo translation of Fascin occurs at the mitotic spindle of sea urchin embryos and mammalian cells. Importantly, miR-31 inhibition leads to a significant a increase of newly translated Fascin at the spindle of dividing sea urchin embryos. Forced ectopic localization of Fascin transcripts to the cell membrane and translation led to significant developmental and chromosomal segregation defects, highlighting the importance of the regulation of local translation by miR-31 at the mitotic spindle to ensure proper cell division. Furthermore, miR-31-mediated post-transcriptional regulation at the mitotic spindle may be an evolutionarily conserved regulatory paradigm of mitosis. [ABSTRACT FROM AUTHOR]

The sea urchin Tripneustes gratilla holds substantial ecological and economic importance in tropical marine ecosystems. To better understand the population structure and genetic diversity of T. gratilla, here we developed a suite of 29 polymorphic microsatellite makers based on high-throughput sequencing. The range of alleles characterized by these primers varied from 6 to 19, with an average number of 12.31. The observed and expected heterozygosities ranged from 0.250 to 1.000 and from 0.808 to 0.955, respectively. All the polymorphism information content values of the 29 loci were above 0.5, suggestive of highly informative. Demonstrating adherence to Hardy–Weinberg equilibrium, these 29 primer pairs present robust candidates for conducting population genetics and phylogeographic analyses in T. gratilla, which may provide valuable information for sustainable management and conservation efforts of this urchin. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos del Centro de Estudios de Diseño y Comunicación is the property of Cuadernos del Centro de Estudios de Diseno y Comunicacion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Echinometra mathaei (family Echinometridae), is one of the sea urchins widely distributed on the Egyptian coasts in the Red Sea. This organism contains edible and non-edible parts. The present study was carried out to analyze and identify the metabolites present in the non-edible parts (Aristotle's lantern and viscera) using LC/MS. Also, the cytotoxic activity on Vero cell line and antiviral activity against herpes simplex virus type 1 were evaluated using MTT colorimetric assay. Results: Chemical profiling of the crude extracts of Aristotle's lantern and viscera using LC/MS indicated the presence of 51 and 59 compounds, respectively. The main metabolites present in both non-edible parts were phospholipids, amino acids, peptides, fatty acids and glycerol derivatives. However, the characteristic difference was the presence of carotenoid pigments only in viscera. The crude extract of Aristotle's lantern and viscera showed no cytotoxic activity on Vero cell line and significant antiviral activity against herpes simplex virus with an IC50 value equal to 115.48 ± 1.20 and 122.4 ± 0.50 µg/mL, respectively. Conclusions: In the present study, the crude extracts of the non-edible parts of E. mathaei were analyzed using LC.MS.MS.QTOF and indicated the existence of 110 chemical compounds, with significant antiviral activity against HSV-1 and no cytotoxic activity. The diversity of the identified compounds with two main categories of compounds, phospholipids and peptides, may contribute to the antiviral activity of Aristotle's lantern and viscera. Additionally, this research focused on clarification of nutritive, pharmaceutical and economic values of these parts. As future prospects, further studies are required to isolate the metabolites and assess the detailed mechanism of antiviral activity via in vitro, in vivo and in silico studies. [ABSTRACT FROM AUTHOR]

Kelp forests have deteriorated globally due to anthropogenic stressors. There is an urgent need to extend baselines, to understand the processes that underlie the persistence and recovery of kelp forests, and to distinguish the normal range of ecosystem variability from more extreme changes. Using a mixed-method, historical ecology approach, we integrate archival data, oral histories, and contemporary ecological data to examine the dynamics of kelp forests over a multi-decadal to multi-century time-period in central California. We focus on sea otters, sunflower seastars, sea urchins, kelp cover, kelp species dynamics, and climate. From 1826 to 2020, kelp was highly variable. There were seven periods of low kelp cover and two periods of exceptionally low kelp cover (1897–1899; 2014–2016) following El Niño-Southern Oscillations (ENSOs). Exceptionally low kelp cover did not occur when two predators—seastars and sea otters—were both present. In all cases, kelp recovered following times of extremely low cover, with a lag, which was extended by the duration of warm water anomalies (ENSO Recovery Lag). Kelp remained low for approximately 2 years following 80% of ENSOs. The greatest kelp decline (12-fold) was in Santa Cruz (northern Monterey Bay). Herbivore populations (sea urchins) were highly variable over the past century and exhibited short- and long-term changes in abundance. Sunflower seastars were present in low, stable abundances prior to seastar wasting disease (1938–2013, mean density = 0.02/m2) when they declined by 97.5%. Insights from this reconstruction indicate that kelp recovery following extended warm water anomalies exhibits a lag and occurs over multiple years. [ABSTRACT FROM AUTHOR]

Drafting gene regulatory networks (GRNs) requires embryological knowledge pertaining to the cell type families, information on the regulatory genes, causal data from gene knockdown experiments and validations of the identified interactions by cis-regulatory analysis. We use multi-omics involving next-generation sequencing to obtain the necessary information for drafting the Strongylocentrotus purpuratus (Sp) posterior gut GRN. Here, we present an update to the GRN using: (1) a single-cell RNA-sequencing-derived cell atlas highlighting the 2 day-post-fertilization (dpf) sea urchin gastrula cell type families, as well as the genes expressed at the single-cell level; (2) a set of putative cis-regulatory modules and transcription factor-binding sites obtained from chromatin accessibility ATAC-seq data; and (3) interactions directionality obtained from differential bulk RNA sequencing following knockdown of the transcription factor Sp-Pdx1, a key regulator of gut patterning in sea urchins. Combining these datasets, we draft the GRN for the hindgut Sp-Pdx1-positive cells in the 2 dpf gastrula embryo. Overall, our data suggest the complex connectivity of the posterior gut GRN and increase the resolution of gene regulatory cascades operating within it. [ABSTRACT FROM AUTHOR]

Alterations in seawater chemistry posed by acidification may lead to immunological and antioxidant defence impairment in sea urchins, with differences among local populations. Here, we analyzed the effects of reduced pH on Paracentrotus lividus, with a multibiomarker approach, and the possible intraspecific variations in sea urchin responses. Two groups of animals with different ecological histories (i.e., the pattern of environmental characteristics and pressures experienced throughout the organism's lifetime) were maintained at ambient pH and pH reduced of 0.4 units for 8 months. Changes in gonadosomatic index (GSI), immunological, and oxidative stress biomarkers were assessed in coelomic fluid, gonads, and digestive tract. Animals maintained at reduced pH showed limited impact of seawater acidification compared to the ambient pH condition. However, sea urchins from the two sites were differently influenced by the seawater pH (as shown by multivariate analyses). GSI and immunological and antioxidant status were differentially modulated between the two sexes, with generally higher values in females, but differences between sexes in relation to the pH of exposure were limited. Overall, our findings highlight that the impact of environmental stressors may differ in sea urchins from different locations. This has implications for the maintenance of P. lividus wild populations under future global change scenarios. [ABSTRACT FROM AUTHOR]

Introduction: In recent decades, Caribbean coral reefs have lost many vital marine species due to diseases. The well-documented mass mortality event of the long-spined black sea urchin Diadema antillarum in the early 1980s stands out among these collapses. This die-off killed over 90% of D. antillarum changing the reefscape from coral to algal-dominated. Nearly 40 years later, D. antillarum populations have yet to recover. In early 2022, a new mortality event of D. antillarum was reported along the Caribbean, including Puerto Rico. Methods: This study identifies the gut microbiota changes associated with the D. antillarum during this mortality event. It contrasts them with the bacterial composition of gut samples from healthy individuals collected in 2019 by using 16S rRNA sequencing analyses. Results: Notably, the die-off group's core microbiome resembled bacteria commonly found in the human skin and gut, suggesting potential anthropogenic contamination and wastewater pollution as contributing factors to the 2022 dysbiosis. The animals collected in 2022, especially those with signs of disease, lacked keystone taxa normally found in Diadema including Photobacterium and Propionigenium. Discussion: The association between human microbes and disease stages in the long-spined urchin D. antillarum, especially in relation to anthropogenic contamination, highlights a complex interplay between environmental stressors and marine health. While these microbes might not be the direct cause of death in this species of sea urchins, their presence and proliferation can indicate underlying issues, such as immune depletion due to pollution, habitat destruction, or climate change, that ultimately compromise the health of these marine organisms. [ABSTRACT FROM AUTHOR]

It is crucial to understand the role of temperature in rearing sea urchin larvae for large-scale production of sea urchin seeds. The development of purple sea urchins, Heliocidaris crassispina, such as fertilization, hatching, embryonic development, larval growth, ingestion, metabolism, and metamorphosis, was investigated at four temperatures: 20, 24, 28, and 32 °C. In the four temperatures, fertilization and hatching of sea urchins first increased with temperature and then decreased. The optimal condition was found at a temperature of 28 °C, where the fertilization and hatching rates exceeded 90%, and embryonic development was highly synchronized. This condition did not differ from the results observed at a temperature of 24 °C (P > 0.05). The fertilization and hatching rates were lower at 20 °C and 32 °C, among which 32 °C had the fastest embryo development but the second highest mortality. In contrast, 20 °C had the slowest embryo development and the most increased mortality. The optimal growth temperature for larvae is 28 °C, at which their growth and development rate are the fastest. However, at 24 °C, it is the second highest. At 20 °C, the growth rate is the lowest, with sluggish physiological responses and the lowest digestion and metabolism capacity. The metamorphosis rate did not differ between 28 and 32 °C (P < 0.05), with 50.0% and 61.1%, respectively, while remaining below 4% at 20 °C. This indicates that temperature significantly impacts the early development of Heliocidaris crassispina sea urchins, whose larvae may be sensitive to low temperatures but have higher temperature tolerance. [ABSTRACT FROM AUTHOR]

Basket height and stocking density are crucial and related factors for successful commercial sea urchin aquaculture, but these factors have not been definitively determined for production of Tripneustes gratilla. This study investigated the effects of varying basket heights (deep 30 cm vs. shallow 15 cm) and stocking densities (4, 6 and 8 kg.m−2 or 13, 19 and 24% coverage of available basket surface area) on aquacultural production of T. gratilla. Contrary to previous suggestions, reduced consumption was identified as the cause of decreased production in deeper baskets. Consumption was significantly higher in shallow baskets than deep baskets for both the fresh seaweed, Ulva lacinulata, (W = 38, p = 0.026) and formulated feed (W = 76.5, p = 0.007). Consequently, baskets of approximately 15 cm deep are recommended to enhance production of T. gratilla and possibly other urchin species. Two subsequent trials assessed production of T. gratilla at different stocking densities. Trial 1 aimed to maximize urchin size over a three-month grow-out period using fresh U. lacinulata, while trial 2 focused on enhancing gonad production over two months using formulated feed. Although greater stocking density significantly reduced the specific growth rates of individual urchin mass in both trials (p < 0.044), there was no significant impact on mortality, net production or gonad size and quality. The variations in growth rates were attributed to spine loss resulting from negative behavioural interactions (F2, 9 = 9.551; p = 0.005). Based on the objectives of both grow-out and gonad-enhancement phases, we recommend a stocking density of approximately 20% coverage. [ABSTRACT FROM AUTHOR]

FoxO is a member of the evolutionary conserved family of transcription factors containing a Forkhead box, involved in many signaling pathways of physiological and pathological processes. In mammals, mutations or dysfunctions of the FoxO gene have been implicated in diverse diseases. FoxO homologs have been found in some invertebrates, including echinoderms. We have isolated the FoxO cDNA from the sea urchin Paracentrotus lividus (Pl-foxo) and characterized the corresponding gene and mRNA. In silico studies showed that secondary and tertiary structures of Pl-foxo protein corresponded to the vertebrate FoxO3 isoform, with highly conserved regions, especially in the DNA-binding domain. A phylogenetic analysis compared the Pl-foxo deduced protein with proteins from different animal species and confirmed its evolutionary conservation between vertebrates and invertebrates. The increased expression of Pl-foxo mRNA following the inhibition of the PI3K signaling pathway paralleled the upregulation of Pl-foxo target genes involved in apoptosis or cell-cycle arrest events (BI-1, Bax, MnSod). In silico studies comparing molecular data from sea urchins and other organisms predicted a network of Pl-foxo protein–protein interactions, as well as identified potential miRNAs involved in Pl-foxo gene regulation. Our data may provide new perspectives on the knowledge of the signaling pathways underlying sea urchin development. [ABSTRACT FROM AUTHOR]

The black sea urchin (Arbacia lixula) is a keystone species inhabiting the coastal shallow waters of the Mediterranean Sea, which is a key driver of littoral communities' structure. Here, we present the first genome assembly and annotation of this species, standing as the first Arbacioida genome, including both nuclear and mitochondrial genomes. To obtain a chromosome-level assembly, we used a combination of PacBio high fidelity (HiFi) reads and chromatin capture reads (Omni-C). In addition, we generated a high-quality nuclear annotation of both coding and non-coding genes, by using published RNA-Seq data from several individuals of A. lixula and gene models from closely related species. The nuclear genome assembly has a total span of 607.91 Mb, being consistent with its experimentally estimated genome size. The assembly contains 22 chromosome-scale scaffolds (96.52% of the total length), which coincides with its known karyotype. A total of 72,767 transcripts were predicted from the nuclear genome, 24,171 coding, and 48,596 non-coding that included lncRNA, snoRNA, and tRNAs. The circularized mitochondrial genome had 15,740 bp comprising 13 protein-coding genes, 2 rRNA, and 22 tRNA. This reference genome will enhance ongoing A. lixula studies and benefit the wider sea urchin scientific community. [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]

Sea urchins produced by aquaculture could enhance declining wild populations and provide a sufficient roe product to satisfy increasing market demand. This study reports a method for large-scale rearing of the edible tropical sea urchin Salmacis sphaeroides, from induction of larval metamorphosis and settlement, to juvenile rearing and grow-out. Larvae were reared in 500-L hatchery tanks, on a diet of the microalga Chaetoceros muelleri at concentrations ranging from 2500 to 24,000 cells mL−1, with daily water renewal of one-third to two-thirds of the volume depending on their developmental stage. The larvae breeding protocol proved suitable for this species, and competent larvae occurred at 12 days post-fertilization. To induce metamorphosis, we tested exposure to potassium chloride (KCl) at different concentrations (0, 25, 50, 100, 200, and 400 mmol L−1) and for different durations (5, 10, and 20 min). Exposure to 200 mmol L−1 KCl for 5 min resulted in the highest proportion of metamorphosed individuals (41.67 ± 2.89 %). Using this method, the densities of juveniles attaching to settlement plates (232.50 ± 41.23 ind. per plate; settlement percentage ca. 3.88 ± 0.69 %) were approximately twice as high as those of the controls (105.75 ± 15.52 ind. per plate; settlement percentage ca. 1.76 ± 0.26 %). Next, two batches of juveniles were grown out in sea cages. In the first batch (deployed for ca. 4 months), the absolute growth rate of the test diameter (AGRD) was 12.79 ± 0.98 mm month−1 from May to September; in the second batch (deployed for 6 months), the AGRD was 5.68 ± 0.90 mm month−1 from October to May of the following year. Survival of the juvenile S. sphaeroides in the sea cages was high (86.56 %–100 %). Finally, the S. sphaeroides cultivated in the second batch were harvested (at a mean test diameter of 71.24 ± 1.45 mm, and wet weight of 101.24 ± 1.91 g) on May 28 of the second year; all animals had matured and could be successfully utilized as broodstock. The fatty acid composition of the gonads was then compared between cultivated and wild-collected adult S. sphaeroides. The proportion of polyunsaturated fatty acids in the cultivated sea urchins (16.59 ± 0.67 %) exceeded that in wild-collected individuals (13.13 ± 0.42 %). From these experiments we conclude that S. sphaeroides is a sea urchin species with excellent potential for aquaculture; the present methods and data will provide helpful information for their mass production in South China.

Background Understanding the dynamics of the gut microbiota in sea urchins is crucial for comprehending the ecological balance in marine ecosystems. The gut microbiota plays a vital role in nutrient metabolism, immune system modulation, and pathogen protection. The microbial composition and dynamics of naturally occurring sea urchin Tripneustes ventricosus have yet to be thoroughly investigated. We hypothesized the gut microbiota of T. ventricosus in the Caribbean, varies across life stages and seasons. Methods Thirty-six naturally occurring large individuals and six small individuals (42 animals) were collected from shallow waters on the northeastern coast of Puerto Rico in February and August of 2019. The fecal pellet’s microbiota was characterized by sequencing V4 region of the 16S rRNA gene. Results We found significant differences in the composition of fecal pellet microbiota between seasons and life stages. Phylum Bacteroidota had greater relative abundance in August, while Firmicutes was more dominant in February. Propionigenium and Roseimarinus had greater relative abundance in August, while Candidatus Hepatoplasma, and Kistimonas had greater relative abundance in February. Differences in the gut digest microbiota were not found between small and large urchins, but small urchins displayed a slightly higher diversity and dominance of Bacteroidota and Proteobacteria, while large urchins exhibited a greater relative abundance of Fusobacteria and Desulfobacterota. However, the genera Ferrominas and Propionigenium counts were significantly lower in small individuals. Discussion This is the first report for this species in the Caribbean region and adds to our comprehension of the microbiota of the white sea urchin across collection periods and size classes, highlighting the dynamic nature of the gut microbiota.

To the best of our knowledge, this study is the first to track and demonstrate the mortality event in Diadema setosum (Leske, 1778) along the Egyptian Red Sea coasts. The diadematid is a group of echinoid echinodermates that play an important ecological role in marine ecosystems. However, the current global mass mortality events in Diadema setosum have the potential to significantly change the fundamental structure of the ecosystem. This report was based on the 2023-summer observations of a D. setosum die-off during an ecological investigation in the northern Red Sea, Egypt. To determine the entirety of the event, a group from the Red Sea protectorates carried out an extensive survey simultaneously. The current survey covered the coastal regions of the Elba protectorate in the south, the Wadi El Gemal protected area in the middle, and Hurghada in the north. A diverse population of D. setosum was found dead on the bottom during both snorkeling and scuba diving. Representative photographs were taken at each explored site. Several features were noticed in the dead D. setosum, including a frail body, sand-covered body parts, spines distributed on the bottom, and inactive tube feet. The current findings, therefore, recommend crucially the performance of regular monitoring for the status of D. setosum. In addition, biological and ecological investigations are needed as soon as possible to interpret the causative and potential factors responsible for D. setosum loss. [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]

Simple Summary: Ocean warming has led to shifts in species distributions. The sea urchin Mesocentrotus nudus is commercially harvested in northern Japan. Although limited scientific reports on the presence of this species in Hokkaido are available from Cape Soya to Cape Erimo along the coast of the Sea of Japan, statistical data from catches indicate that it has extended its range to the Sea of Okhotsk and Pacific Ocean. In 2021, harmful algal blooms (HABs) occurred along the Pacific coast of Hokkaido, and massive die-offs of marine organisms, including M. nudus, were reported. This study aimed to redefine the presence of M. nudus in the Pacific Ocean off Hokkaido after the HABs. Field surveys were conducted, and M. nudus was confirmed in Akkeshi, the site farthest from Cape Soya among the areas where irregular catches of M. nudus were recorded in eastern Hokkaido, in 2023. All sea urchins were >6 years of age, indicating that they survived the HABs. The size and developmental stages of the ovaries and testes of collected individuals suggest the reproductive cycle of M. nudus in Akkeshi would synchronize with that of the specimens off Wakkanai, Cape Soya. Warming trends may lead to population increases in the future. Scientific reports on the distribution of Mesocentrotus nudus in Hokkaido are limited from Cape Soya to Cape Erimo along the coast of the Sea of Japan; however, fishery statistics show that its distribution has extended to the Sea of Okhotsk and Pacific Ocean off Hokkaido. In 2021, large-scale harmful algal blooms (HABs) occurred in the Pacific Ocean off eastern Hokkaido, resulting in the massive die-off of marine organisms, including M. nudus. This study aimed to redefine the distribution of M. nudus in the Pacific Ocean off eastern Hokkaido after the HABs. Field surveys were conducted in July, August, and December 2023 in Akkeshi, the site farthest from Cape Soya among the areas where irregular catches of M. nudus have been recorded in eastern Hokkaido, and the distribution of this species was confirmed in August and December. All sea urchins collected were >6 years of age, indicating that they survived the HABs. High gonad indices and spermatozoa-filled gonads were observed in the sea urchins collected in December, suggesting that the reproductive cycle of M. nudus in Akkeshi may be close to that observed in specimens off Wakkanai, Cape Soya. Warming trends may cause population increases in the future. [ABSTRACT FROM AUTHOR]