Strongylocentrotus Purpuratus Research Articles

Exploring indirect effects of a classic trophic cascade between urchins and kelp on zooplankton and whales

Kelp forest trophic cascades have been extensively researched, yet indirect effects to the zooplankton prey base and gray whales have not been explored. We investigate the correlative patterns of a trophic cascade between bull kelp and purple sea urchins on gray whales and zooplankton in Oregon, USA. Using generalized additive models (GAMs), we assess (1) temporal dynamics of the four species across 8 years, and (2) possible trophic paths from urchins to kelp, kelp as habitat to zooplankton, and kelp and zooplankton to gray whales. Temporal GAMs revealed an increase in urchin coverage, with simultaneous decline in kelp condition, zooplankton abundance and gray whale foraging time. Trophic path GAMs, which tested for correlations between species, demonstrated that urchins and kelp were negatively correlated, while kelp and zooplankton were positively correlated. Gray whales showed nuanced and site-specific correlations with zooplankton in one site, and positive correlations with kelp condition in both sites. The negative correlation between the kelp-urchin trophic cascade and zooplankton resulted in a reduced prey base for gray whales. This research provides a new perspective on the vital role kelp forests may play across multiple trophic levels and interspecies linkages.

Recombinant SpTransformer proteins are functionally diverse for binding and phagocytosis by three subtypes of sea urchin phagocytes.

The California purple sea urchin, Strongylocentrotus purpuratus, relies solely on an innate immune system to combat the many pathogens in the marine environment. One aspect of their molecular defenses is the SpTransformer (SpTrf) gene family that is upregulated in response to immune challenge. The gene sequences are highly variable both within and among animals and likely encode thousands of SpTrf isoforms within the sea urchin population. The native SpTrf proteins bind foreign targets and augment phagocytosis of a marine Vibrio. A recombinant (r)SpTrf-E1-Ec protein produced by E. coli also binds Vibrio but does not augment phagocytosis. To address the question of whether other rSpTrf isoforms function as opsonins and augment phagocytosis, six rSpTrf proteins were expressed in insect cells. The rSpTrf proteins are larger than expected, are glycosylated, and one dimerized irreversibly. Each rSpTrf protein cross-linked to inert magnetic beads (rSpTrf::beads) results in different levels of surface binding and phagocytosis by phagocytes. Initial analysis shows that significantly more rSpTrf::beads associate with cells compared to control BSA::beads. Binding specificity was verified by pre-incubating the rSpTrf::beads with antibodies, which reduces the association with phagocytes. The different rSpTrf::beads show significant differences for cell surface binding and phagocytosis by phagocytes. Furthermore, there are differences among the three distinct types of phagocytes that show specific vs. constitutive binding and phagocytosis. These findings illustrate the complexity and effectiveness of the sea urchin innate immune system driven by the natSpTrf proteins and the phagocyte cell populations that act to neutralize a wide range of foreign pathogens.

Characterization of thyrotropin-releasing hormone producing neurons in sea urchin, from larva to juvenile.

Most sea urchin species are indirect developers, going through a larval stage called pluteus. The pluteus possesses its own nervous system, consisting mainly of the apical organ neurons (controlling metamorphosis and settlement) and ciliary band neurons (controlling swimming behavior and food collection). Additional neurons are located in various areas of the gut. In recent years, the molecular complexity of this apparently "simple" nervous system has become apparent, with at least 12 neuronal populations identified through scRNA-sequencing in the species Strongylocentrotus purpuratus. Among these, there is a cluster of neurosecretory cells that produce a thyrotropin-releasing hormone-type neuropeptide (TRHergic) and that are also photosensory (expressing a Go-Opsin). However, much less is known about the organization of the nervous system in other sea urchin species. The aim of this work was to thoroughly characterize the localization of the TRHergic cells from early pluteus to juvenile stages in the Mediterranean sea urchin species Paracentrotus lividus combining immunostaining and whole mount in situ hybridization. We also compared the localization of TRHergic cells in early plutei of two other sea urchin species, Arbacia lixula and Heliocidaris tuberculata. This work provides new information on the anatomy and development of the nervous system in sea urchins. Moreover, by comparing the molecular signature of the TRHergic cells in P. lividus and S. purpuratus, we have obtained new insights how TRH-type neuropeptide signaling evolved in relatively closely related species.

Kelp-associated variability in seawater chemistry during a marine heatwave event connects to transgenerational effects in the purple urchin Strongylocentrotus purpuratus

Giant kelp Macrocystis pyrifera provides the foundation for immense biodiversity on the coast of California, USA. Kelp forests can change seawater retention time, altering water chemistry, including pH and dissolved oxygen (DO), as well as the magnitude and predictability of variability in the same properties. Environmental heterogeneity across space and time could drive organismal performance and processes such as transgenerational plasticity (TGP), where parental experience modifies the offspring phenotype, potentially conferring tolerance to future environmental stress. We monitored environmental variability by deploying temperature, pH, and DO sensors inside and outside a temperate kelp forest in the Santa Barbara Channel (SBC) throughout the gametogenesis period of a key herbivore, the purple urchin Strongylocentrotus purpuratus. Over the 6 mo period, pH and temperature were slightly elevated inside the kelp forest, accompanied by more predictable, low-frequency variability relative to outside. Adult S. purpuratus were conditioned inside and outside the kelp spanning gametogenesis. The urchins were spawned and their larvae were raised under high (1053 µatm) and low pCO2 (435 µatm) at 15°C in the laboratory to assess their physiological response to the maternal and developmental environments. Larvae raised under high pCO2 were more susceptible to acute thermal stress; however, within each larval treatment, progeny from outside-conditioned mothers had a 0.4°C higher lethal temperature (LT50). Our results indicate that heterogeneity in abiotic factors associated with kelp can have transgenerational effects in the field, and interactions between factors, including temperature and pH, will impact purple urchins as local variability associated with marine heatwaves and upwelling evolves with climate change.

Functional Analyses of Four Cryptochromes From Aquatic Organisms After Heterologous Expression in Drosophila melanogaster Circadian Clock Cells.

Cryptochromes (Crys) represent a multi-facetted class of proteins closely associated with circadian clocks. They have been shown to function as photoreceptors but also to fulfill light-independent roles as transcriptional repressors within the negative feedback loop of the circadian clock. In addition, there is evidence for Crys being involved in light-dependent magneto-sensing, and regulation of neuronal activity in insects, adding to the functional diversity of this cryptic protein class. In mammals, Crys are essential components of the circadian clock, but their role in other vertebrates is less clear. In invertebrates, Crys can function as circadian photoreceptors, or as components of the circadian clock, while in some species, both light-receptive and clock factor roles coexist. In the current study, we investigate the function of Cry proteins in zebrafish (Danio rerio), a freshwater teleost expressing 6 cry genes. Zebrafish peripheral circadian clocks are intrinsically light-sensitive, suggesting the involvement of Cry in light-resetting. Echinoderms (Strongylocentrotus purpuratus) represent the only class of deuterostomes that possess an orthologue (SpuCry) of the light-sensitive Drosophila melanogaster Cry, which is an important component of the light-resetting pathway, but also works as transcriptional repressor in peripheral clocks of fruit flies. We therefore investigated the potential of different zebrafish cry genes and SpuCry to replace the light-resetting and repressor functions of Drosophila Cry by expressing them in fruit flies lacking endogenous cry function. Using various behavioral and molecular approaches, we show that most Cry proteins analyzed are able to fulfill circadian repressor functions in flies, except for one of the zebrafish Crys, encoded by cry4a. Cry4a also shows a tendency to support light-dependent Cry functions, indicating that it might act in the light-input pathway of zebrafish.

Tropomyosin induces the synthesis of magnesian calcite in sea urchin spines

Calcium carbonate is present in many biominerals, including in the exoskeletons of crustaceans and shells of mollusks. High Mg-containing calcium carbonate was synthesized by high temperatures, high pressures or high molecular organic matter. For example, biogenic high Mg-containing calcite is synthesized under strictly controlled Mg concentration at ambient temperature and pressure. The spines of sea urchins consist of calcite, which contain a high percentage of magnesium. In this study, we investigated the factors that increase the magnesium content in calcite from the spines of the sea urchin, Heliocidaris crassispina. X-ray diffraction and inductively coupled plasma mass spectrometry analyses showed that sea urchin spines contain about 4.8% Mg. The organic matrix extracted from the H. crassispina spines induced the crystallization of amorphous phase and synthesis of magnesium-containing calcite, while amorphous was synthesized without SUE (sea urchin extract). In addition, aragonite was synthesized by SUE treated with protease-K. HC tropomyosin was specifically incorporated into Mg precipitates. Recombinant HC-tropomyosin induced calcite contained 0.1–2.5% Mg synthesis. Western blotting of sea urchin spine extracts confirmed that HC tropomyosin was present in the purple sea urchin spines at a protein weight ratio of 1.5%. These results show that HC tropomyosin is one factor that increases the magnesium concentration in the calcite of H. crassispina spines.

Nutrient enrichment and probiotics for sea urchin Anthocidaris crassipina larvae in captivity to promote large-scale aquaculture.

Sea urchin contains physiologically active substances, such as amino acids and unsaturated fatty acids, and an important aquatic organism. Purple sea urchin, one of the common edible sea urchins, is an important aquatic product. In order to supply the vast seafood market, large-scale aquaculture of sea urchins is very important. The aim of this study was to optimize the rearing of theAnthocidaris crassipina larvae enhancing the nutrition by mixing feed to improve their growth and survival. The survival rate of Chaetoceros muelleri feeding alone is only 40%. If the survival rate is improved through nutrient enrichment, the large-scale aquaculture of larvae can be promoted. The experiment was divided into two parts. Experiment 1: Two types of commonly used microalgae, Isochrysis galbana tml (I), C. muelleri (C) and two types of probiotics, Rhodopseudomonas palustris (R), and Saccharomyces cerevisiae (S) were used in the.Feeding amounts are 5000, 10,000, and 20,000 cell mL-1 , and the control group (N) did not eat. Experiment 2: C. muelleri 20,000 cell mL-1 was mixed with I. galbana tml, R. palustris (R)and S. cerevisiae (S) at 5000 and 10,000 cell mL-1 . After the experiment, body length, body width, stomach length, rudiment length, rudiment length, body composition, digestive enzymes and survival rate were measured to evaluate the best feed. The results showed that the mixed feeding of C. muelleri 20,000 cell mL-1 and R. palustris 5000 cell mL-1 can achieve the best development and survival of larval embryos and can promote metamorphosis into juveniles in the shortest time. The research results will be applied to the large-scale aquaculture of A. crassipina larvae to promote the diversity of aquaculture.

Cold storage and cryopreservation methods for spermatozoa of the sea urchins Lytechinus pictus and Strongylocentrotus purpuratus

AbstractBackgroundSea 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.ResultsHere, 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.ConclusionsThe 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.

Local Genomic Instability of the SpTransformer Gene Family in the Purple Sea Urchin Inferred from BAC Insert Deletions.

The SpTransformer (SpTrf) gene family in the purple sea urchin, Strongylocentrotus purpuratus, encodes immune response proteins. The genes are clustered, surrounded by short tandem repeats, and some are present in genomic segmental duplications. The genes share regions of sequence and include repeats in the coding exon. This complex structure is consistent with putative local genomic instability. Instability of the SpTrf gene cluster was tested by 10 days of growth of Escherichia coli harboring bacterial artificial chromosome (BAC) clones of sea urchin genomic DNA with inserts containing SpTrf genes. After the growth period, the BAC DNA inserts were analyzed for size and SpTrf gene content. Clones with multiple SpTrf genes showed a variety of deletions, including loss of one, most, or all genes from the cluster. Alternatively, a BAC insert with a single SpTrf gene was stable. BAC insert instability is consistent with variations in the gene family composition among sea urchins, the types of SpTrf genes in the family, and a reduction in the gene copy number in single coelomocytes. Based on the sequence variability among SpTrf genes within and among sea urchins, local genomic instability of the family may be important for driving sequence diversity in this gene family that would be of benefit to sea urchins in their arms race with marine microbes.

Genome-Wide Comparative Analysis of SRCR Gene Superfamily in Invertebrates Reveals Massive and Independent Gene Expansions in the Sponge and Sea Urchin.

Without general adaptative immunity, invertebrates evolved a vast number of heterogeneous non-self recognition strategies. One of those well-known adaptations is the expansion of the immune receptor gene superfamily coding for scavenger receptor cysteine-rich domain containing proteins (SRCR) in a few invertebrates. Here, we investigated the evolutionary history of the SRCR gene superfamily (SRCR-SF) across 29 metazoan species with an emphasis on invertebrates. We analyzed their domain architectures, genome locations and phylogenetic distribution. Our analysis shows extensive genome-wide duplications of the SRCR-SFs in Amphimedon queenslandica and Strongylocentrotus purpuratus. Further molecular evolution study reveals various patterns of conserved cysteines in the sponge and sea urchin SRCR-SFs, indicating independent and convergent evolution of SRCR-SF expansion during invertebrate evolution. In the case of the sponge SRCR-SFs, a novel motif with seven conserved cysteines was identified. Exon-intron structure analysis suggests the rapid evolution of SRCR-SFs during gene duplications in both the sponge and the sea urchin. Our findings across nine representative metazoans also underscore a heightened expression of SRCR-SFs in immune-related tissues, notably the digestive glands. This observation indicates the potential role of SRCR-SFs in reinforcing distinct immune functions in these invertebrates. Collectively, our results reveal that gene duplication, motif structure variation, and exon-intron divergence might lead to the convergent evolution of SRCR-SF expansions in the genomes of the sponge and sea urchin. Our study also suggests that the utilization of SRCR-SF receptor duplication may be a general and basal strategy to increase immune diversity and tissue specificity for the invertebrates.

Effects of temperature on fertilization, hatching, larval growth, ingestion, metabolism, and metamorphosis of the purple sea urchins, Heliocidaris crassispina

Effects of temperature on fertilization, hatching, larval growth, ingestion, metabolism, and metamorphosis of the purple sea urchins, Heliocidaris crassispina

Assessment of annual variability in the population status and reproductive cycle of purple sea urchins (Heliocidaris crassispina, Agassiz, 1864) in Daya Bay, China

The purple sea urchin (Heliocidaris crassispina) is one of the main drivers of ecosystem dynamics, and its reproductive cycle plays an important role in population structure and size variability. In this study, we analyzed the population structure, gonadal developmental characteristics, reproductive cycle and other factors influencing wild purple sea urchins from December 2021 to November 2022 in Daya Bay, Guangdong, China. The results showed that purple sea urchins showed an allometric growth pattern, there were obvious seasonal variations in the population size, and fishing pressure reduced the sea urchin populations; two-factor analysis of variance (ANOVA) and correlation analyses showed negative correlations between month (M), test diameter (TD), weight (W) and gonadal index (GI) (P> 0.01), and a positive correlation between TD, weight (W), and GI (P<0.01); the gonadal development process can be divided into recovery, growth, prematuration, maturation, and late discharge, with almost synchronous development of male and female gametes; the spawning period is from April to November, which is longer than in the temperate zones, showing two spawning peaks in April and August. The time of spawning is influenced by temperature and food. Data on the breeding cycle of sea urchins in Daya Bay were obtained in this study. This information can offer theoretical assistance in the preservation and management of both artificial nurseries and wild resources.

Spotting disease disrupts the microbiome of infected purple sea urchins, Strongylocentrotus purpuratus

BackgroundSpotting disease infects a variety of sea urchin species across many different marine locations. The disease is characterized by discrete lesions on the body surface composed of discolored necrotic tissue that cause the loss of all surface appendages within the lesioned area. A similar, but separate disease of sea urchins called bald sea urchin disease (BSUD) has overlapping symptoms with spotting disease, resulting in confusions in distinguishing the two diseases. Previous studies have focus on identifying the underlying causative agent of spotting disease, which has resulted in the identification of a wide array of pathogenic bacteria that vary based on location and sea urchin species. Our aim was to investigate the spotting disease infection by characterizing the microbiomes of the animal surface and various tissues.ResultsWe collected samples of the global body surface, the lesion surface, lesioned and non-lesioned body wall, and coelomic fluid, in addition to samples from healthy sea urchins. 16S rRNA gene was amplified and sequenced from the genomic DNA. Results show that the lesions are composed mainly of Cyclobacteriaceae, Cryomorphaceae, and a few other taxa, and that the microbial composition of lesions is the same for all infected sea urchins. Spotting disease also alters the microbial composition of the non-lesioned body wall and coelomic fluid of infected sea urchins. In our closed aquarium systems, sea urchins contracted spotting disease and BSUD separately and therefore direct comparisons could be made between the microbiomes from diseased and healthy sea urchins.ConclusionResults show that spotting disease and BSUD are separate diseases with distinct symptoms and distinct microbial compositions.Graphical abstract

Evaluating the time to detect biological effects of ocean acidification and warming: an example using simulations of purple sea urchin settlement

Evaluating the time to detect biological effects of ocean acidification and warming: an example using simulations of purple sea urchin settlement

Genome-wide identification and spatiotemporal expression analysis of cadherin superfamily members in echinoderms

BackgroundCadherins are calcium-dependent transmembrane cell–cell adhesion proteins that are essential for metazoan development. They consist of three subfamilies: classical cadherins, which bind catenin, protocadherins, which contain 6–7 calcium-binding repeat domains, and atypical cadherins. Their functions include forming adherens junctions, establishing planar cell polarity (PCP), and regulating cell shape, proliferation, and migration. Because they are basal deuterostomes, echinoderms provide important insights into bilaterian evolution, but their only well-characterized cadherin is G-cadherin, a classical cadherin that is expressed by many embryonic epithelia. We aimed to better characterize echinoderm cadherins by conducting phylogenetic analyses and examining the spatiotemporal expression patterns of cadherin-encoding genes during Strongylocentrotus purpuratus development.ResultsOur phylogenetic analyses conducted on two echinoid, three asteroid, and one crinoid species identified ten echinoderm cadherins, including one deuterostome-specific ortholog, cadherin-23, and an echinoderm-specific atypical cadherin that possibly arose in an echinoid-asteroid ancestor. Catenin-binding domains in dachsous-2 orthologs were found to be a deuterostome-specific innovation that was selectively lost in mouse, while those in Fat4 orthologs appeared to be Ambulacraria-specific and were selectively lost in non-crinoid echinoderms. The identified suite of echinoderm cadherins lacks vertebrate-specific innovations but contains two proteins that are present in protostomes and absent from mouse. The spatiotemporal expression patterns of four embryonically expressed cadherins (fat atypical cadherins 1 and 4, dachsous-2, and protocadherin-9) were dynamic and mirrored the expression pattern of Frizzled 5/8, a non-canonical Wnt PCP pathway receptor protein essential for archenteron morphogenesis.ConclusionsThe echinoderm cadherin toolkit is more similar to that of an ancient bilaterian predating protostomes and deuterostomes than it is to the suite of cadherins found in extant vertebrates. However, it also appears that deuterostomes underwent several cadherin-related innovations. Based on their similar spatiotemporal expression patterns and orthologous relationships to PCP-related and tumor-suppressing proteins, we hypothesize that sea urchin cadherins may play a role in regulating the shape and growth of embryonic epithelia and organs. Future experiments will examine cadherin expression in non-echinoid echinoderms and explore the functions of cadherins during echinoderm development.

Sea urchin Arbacia punctulata feeding preference for algal turf over kelp in a degraded kelp forest ecosystem

Climate change is driving a shift in the distribution of global kelp forests, with the contraction of kelp habitats occurring at warm range edges. Declining kelps often have been replaced by novel algal turf assemblages, which are reinforced by ecological feedback mechanisms and provide fewer ecosystem services. Trophic interactions among marine herbivores, algal turfs, and kelps on algal turf-dominated reefs remain poorly resolved but could have important implications for the stability of algal turf reefs and the potential for kelp forest recovery. Here, we examine herbivory by the Atlantic purple sea urchin, Arbacia punctulata, in a degraded kelp forest ecosystem dominated by algal turf in southern New England, USA. In a localized field survey, we observed lower algal turf cover on reef areas containing A. punctulata (mean ± SE: 62 ± 12% turf cover) as compared to areas with no sea urchins present (92 ± 4% turf cover). Reef areas with and without sea urchins had similarly low cover of the previously dominant kelp, Saccharina latissima (6–8% kelp cover). In laboratory and field experiments, individuals or groups of A. punctulata enclosed with a diet choice of algal turf versus kelp had higher grazing rates on the algal turf. A. punctulata in the laboratory also exhibited greater attraction to algal turf over kelp, physically moving towards this food source. In combination, the results provide evidence that A. punctulata has a feeding preference for algal turf over kelp in southern New England. Future research is warranted to further examine the grazing ecology of A. punctulata, particularly in the context of ongoing kelp forest restoration efforts in this region.

Conservation and contrast in cell states of echinoderm ovaries.

Echinoderms produce functional gametes throughout their lifespan, in some cases exceeding 200 years. The histology and ultrastructure of echinoderm ovaries has been described but how these ovaries function and maintain the production of high-quality gametes remainsa mystery. Here, we present the first single cell RNA sequencingdata sets of mature ovaries from two sea urchin species (Strongylocentrotus purpuratus [Sp] and Lytechinus variegatus [Lv]), and one sea star species (Patiria miniata [Pm]). We find 14 cell states in the Sp ovary, 16 cell states in the Lv ovary and 13 cell states in the ovary of the sea star. This resource is essential to understand the structure and functional biology of the ovary in echinoderms, and better informs decisions in the utilization of in situ RNAhybridization probes selective for various cell types. We link key genes with cell clusters in validation of this approach. This resource also aids in the identification of the stem cells for prolonged and continuous gamete production, is a foundation for testing changes in the annual reproductive cycle, and is essential for understanding the evolution of reproduction of this important phylum.

The role of kelp availability and quality on the energetic state and thermal tolerance of sea urchin and gastropod grazers

Widespread decline in underwater forests, formed by kelps and other macroalgae, is occurring in all oceans. Loss of the vulnerable surface canopy typically leads to alternate rocky reef states dominated by substrate-near, understory vegetation, or reefs without any large fleshy macroalgae such as sea urchin barrens. Such alternate reef states represent a major shift in food availability and quality, and may impact kelp-preferring grazers forced to rely on less nutritious foods. Here we investigate the physiological responses of grazers to changes in food quality and quantity. We quantify the mass-independent oxygen consumption (ṀO2), as a proxy of whole-organism physiology, of four grazing invertebrate species (two sea urchins: Mesocentrotus franciscanus and Strongylocentrotus purpuratus; and two gastropods: Pomaulax gibberosus and Tegula pulligo) provisioned with one of three diet treatments over seven weeks: 1) higher quality, canopy kelp, 2) lower quality, substrate-near kelp, or 3) restricted: no kelp. We further test for differences in the heat resistance of four grazers using an acute, near-lethal heat exposure after completion of the provisioning period. Food restrictions had the strongest influence on oxygen consumption in the two urchins (mass-independent ṀO2 was reduced by 26–78%). By contrast, the two gastropod grazers did not display metabolic depression under food restrictions. Although kelp restrictions had clear physiological consequences in sea urchins, overall, the type of kelp provisioned (Macrocystis and Saccharina) did not relate to oxygen consumption after seven weeks. While heat resistance was also similar across food treatments, unfed individuals showed a slight tendency for lower heat tolerance compared to fed individuals. These results suggest a weak coupling between heat resistance and food quality and quantity, at least for these species and at short time spans. Our work highlights the importance of diet diversity and metabolic depression as strategies to cope with the energetic costs of warming.

Evaluating restriction enzyme selection for reduced representation sequencing in conservation genomics.

Conservation genomic studies in non-model organisms generally rely on reduced representation sequencing techniques based on restriction enzymes to identify population structure as well as candidate loci for local adaptation. While the expectation is that the reduced representation of the genome is randomly distributed, the proportion of the genome sampled might depend on the GC content of the recognition site of the restriction enzyme used. Here, we evaluated the distribution and functional composition of loci obtained after a reduced representation approach using Genotyping-by-Sequencing (GBS). To do so, we compared experimental data from two endemic fish species (Symphodus ocellatus and Symphodus tinca, EcoT22I enzyme) and two ecosystem engineer sea urchins (Paracentrotus lividus and Arbacia lixula, ApeKI enzyme). In brief, we mapped the sequenced loci to the phylogenetically closest reference genome available (Labrus bergylta in the fish and Strongylocentrotus purpuratus in the sea urchin datasets), classified them as exonic, intronic and intergenic, and studied their function by using Gene Ontology (GO) terms. We also simulated the effect of using both enzymes in the two reference genomes. In both simulated and experimental data, we detected an enrichment towards exonic or intergenic regions depending on the restriction enzyme used and failed to detect differences between total loci and candidate loci for adaptation in the empirical dataset. Most of the functions assigned to the mapped loci were shared between the four species and involved a myriad of general functions. Our results highlight the importance of restriction enzyme selection and the need for high-quality annotated genomes in conservation genomic studies.

A Second Life for Seafood Waste: Therapeutical Promises of Polyhydroxynapthoquinones Extracted from Sea Urchin by-Products.

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