Sea Urchin Arbacia Lixula Research Articles

Reproductive toxicity assessment of cellulose nanofibers, citric acid, and branched polyethylenimine in sea urchins: Eco-design of nanostructured cellulose sponge framework (Part B)

In the framework of a safe-by-design approach, we previously assessed the eco-safety of nanostructured cellulose sponge (CNS) leachate on sea urchin reproduction. It impaired gamete quality, gamete fertilization competence, and embryo development possibly due to the leaching of chemical additives used during the CNS synthesis process. To extend this observation and identify the component(s) that contribute to CNS ecotoxicity, in the present study, we individually screened the cytotoxic effects on sea urchin Arbacia lixula and Paracentrotus lividus gametes and embryos of the three main constituents of CNS, namely cellulose nanofibers, citric acid, and branched polyethylenimine. The study aimed to minimize any potential safety risk of these components and to obtain an eco-safe CNS. Among the three CNS constituents, branched polyethylenimine resulted in the most toxic agent. Indeed, it affected the physiology and fertilization competence of male and female gametes as well as embryo development in both sea urchin species. These results are consistent with those previously reported for CNS leachate. Moreover, the characterisation of CNS leachate confirmed the presence of detectable branched polyethylenimine in the conditioned seawater even though in a very limited amount. Altogether, these data indicate that the presence of branched polyethylenimine is a cause-effect associated with a significant risk in CNS formulations due to its leaching upon contact with seawater. Nevertheless, the suggested safety protocol consisting of consecutive leaching treatments and conditioning of CNS in seawater can successfully ameliorate the CNS ecotoxicity while maintaining the efficacy of its sorbent properties supporting potential environmental applications.

In Vitro Anti-Inflammatory and Vasculoprotective Effects of Red Cell Extract from the Black Sea Urchin Arbacia lixula.

Sea urchins have emerged as an important source of bioactive compounds with anti-inflammatory and antioxidant properties relevant to human health. Since inflammation is a crucial pathogenic process in the development and progression of atherosclerosis, we here assessed the potential anti-inflammatory and vasculoprotective effects of coelomic red-cell methanolic extract of the black sea urchin Arbacia lixula in an in vitro model of endothelial cell dysfunction. Human microvascular endothelial cells (HMEC-1) were pretreated with A. lixula red-cell extract (10 and 100 μg/mL) before exposure to the pro-inflammatory cytokine tumor necrosis factor (TNF)-α. The extract was non-toxic after 24 h cell treatment and was characterized by antioxidant power and phenol content. The TNF-α-stimulated expression of adhesion molecules (VCAM-1, ICAM-1) and cytokines/chemokines (MCP-1, CCL-5, IL-6, IL-8, M-CSF) was significantly attenuated by A. lixula red-cell extract. This was functionally accompanied by a reduction in monocyte adhesion and chemotaxis towards activated endothelial cells. At the molecular level, the tested extract significantly counteracted the TNF-α-stimulated activation of the pro-inflammatory transcription factor NF-κB. These results provide evidence of potential anti-atherosclerotic properties of A. lixula red-cell extract, and open avenues in the discovery and development of dietary supplements and/or drugs for the prevention or treatment of cardiovascular diseases.

Polymer Chemical Identity as a Key Factor in Microplastic-Insecticide Antagonistic Effects during Embryogenesis of Sea Urchin Arbacia lixula.

As a proxy for pollutants that may be simultaneously present in urban wastewater streams, the effects of two microplastics-polystyrene (PS; 10, 80 and 230 μm diameter) and polymethylmethacrylate (PMMA; 10 and 50 μm diameter)-on fertilisation and embryogenesis in the sea urchin Arbacia lixula with co-exposure to the pyrethroid insecticide cypermethrin were investigated. Synergistic or additive effects were not seen for plastic microparticles (50 mg L-1) in combination with cypermethrin (10 and 1000 μg L-1) based on evaluation of skeletal abnormalities or arrested development and death of significant numbers of larvae during the embryotoxicity assay. This behaviour was also apparent for male gametes pretreated with PS and PMMA microplastics and cypermethrin, where a reduction in sperm fertilisation ability was not evidenced. However, a modest reduction in the quality of the offspring was noted, suggesting that there may be some transmissible damage to the zygotes. PMMA microparticles were more readily taken up than PS microparticles, which could suggest surface chemical identity as potentially modulating the affinity of larvae for specific plastics. In contrast, significantly reduced toxicity was noted for the combination of PMMA microparticles and cypermethrin (100 μg L-1), and may be related to less ready desorption of the pyrethroid than PS, as well as cypermethrin activating mechanisms that result in reduced feeding and hence decreased ingestion of microparticles.

Effects of Sulfamethoxazole on Fertilization and Embryo Development in the Arbacia lixula Sea Urchin.

Simple SummaryDrugs released into the aquatic environment create serious problems for the organisms that live there. For this reason, the present study investigates the in vitro effects of the antibiotic sulfamethoxazole, widely found in wastewater, on the fertilization and development of the Arbacia lixula sea urchin. The results showed a significant reduction in the percentage of fertilized oocytes at the highest drug concentrations, together with an increase in anomalies and delays in the development of the embryo. Therefore, the data obtained suggest urgent intervention on the release of these drugs in order to prevent important alterations in the species’ development and to preserve biodiversity.To date, drugs released into the aquatic environment are a real problem, and among antibiotics, sulfamethoxazole is the one most widely found in wastewater; thus, the evaluation of its toxicity on marine organisms is very important. This study, for the first time, investigates the in vitro effects of 4 concentrations of sulfamethoxazole (0.05 mg/L, 0.5 mg/L, 5 mg/L, 50 mg/L) on the fertilization and development of the sea urchin Arbacia lixula. The gametes were exposed to drugs in three different stages: simultaneously with, prior to, and post-fertilization. The results show a significant reduction in the percentage of fertilized oocytes at the highest drug concentrations. Moreover, an increase in anomalies and delays in embryo development following the treatment with the drug was demonstrated. Therefore, the data suggest that this antibiotic can alter the development of marine organisms, making it urgent to act to reduce their release and to determine the concentration range with the greatest impact.

Biological and Proteomic Characterization of the Anti-Cancer Potency of Aqueous Extracts from Cell-Free Coelomic Fluid of Arbacia lixula Sea Urchin in an In Vitro Model of Human Hepatocellular Carcinoma

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

Effects of diclofenac on the gametes and embryonic development of Arbacia lixula

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

The Two Sides of the Mediterranean: Population Genomics of the Black Sea Urchin Arbacia lixula (Linnaeus, 1758) in a Warming Sea

Global environmental changes may have a profound impact on ecosystems. In this context, it is crucial to gather biological and ecological information of the main species in marine communities to predict and mitigate potential effects of shifts in their distribution, abundance, and interactions. Using genotyping by sequencing (GBS), we assessed the genetic structure of a keystone species in the Mediterranean shallow littoral ecosystems, the black sea urchin Arbacia lixula. This bioengineer species can shape their communities due to its grazing activity and it is experiencing an ongoing expansion with increasing temperatures. The population genomic analyses on 5,241 loci sequenced in 240 individuals from 11 Mediterranean sampled populations revealed that all populations were diverse and showed significant departure from equilibrium. Albeit genetic differentiation was in general shallow, a significant break separated the western and eastern Mediterranean populations, a break not detected in previous studies with less resolutive markers. Notably, no clear effect of the Almería-Oran front, an important break in the Atlanto-Mediterranean transition, could be detected among the western basin populations, where only a slight differentiation of the two northernmost populations was found. Despite the generally low levels of genetic differentiation found, we identified candidate regions for local adaptation by combining different genomic analysis with environmental data. Salinity, rather than temperature, seemed to be an important driver of genetic structure in A. lixula. Overall, from a population genomics standpoint, there is ample scope for A. lixula to continue thriving and adapting in the warming Mediterranean.

Fertilization and development of Arbacia lixula eggs are affected by osmolality conditions

The sea urchin Arbacia lixula coexist with Paracentrotus lividus in the Mediterranean, but the two sea urchin species are quite different from each other. Concerning the female gamete, A. lixula eggs are much darker than those of P. lividus due to the characteristic pigmentation. Upon insemination, the fertilization envelope formed by A. lixula eggs is remarkably thinner than that of P. livius eggs, which implies that the cortical organization of the eggs in the two species may be quite different. In this communication, we examined the phenotypic plasticity of A. lixula eggs in the changing osmolality. The plasma membrane, cortical actin cytoskeleton and vesicles are extensively altered in the eggs exposed to 40% seawater for 15 min. When fertilized, the Ca2+ response in these eggs was significantly compromised and the sperm often failed to enter the eggs. Remarkably, the pattern of the Ca2+ response was restored when these eggs were transferring back to the natural seawater before fertilization, while the actin cytoskeleton partially reverted to the original state. Nonetheless, these eggs restored in seawater failed to regain the innate sperm receptivity that allows only one sperm to enter in natural seawater. Thus, the ability to guide monospermic fertilization is lost by water entry into the eggs, and the eggs incorporated either multiple or no sperm. On the other hand, eggs briefly exposed to hypertonic seawater exhibited no evident morphological anomaly. Nonetheless, the monospermic eggs that experienced a brief exposure (15 min) to hypertonic seawater prior to fertilization in natural seawater displayed a subtly altered sperm-induced Ca2+ response and morpho-functional anomaly around the pluteus stage. Our results suggest that A. lixula eggs attain only a limited extent of cytological plasticity, and that the osmolality shock affects the physical nature of the egg surface which in turn affects the developmental programming.

Interpopulation variability of the reproductive cycle of Arbacia lixula (Echinodermata: Echinoidea) in the Mostaganem shallow-water area (south-western Mediterranean)

The study on the reproductive biology of the black sea urchin Arbacia lixula was carried out at two different sites on the west coast of Algeria (Mostaganem) (one located at Salamandre considered polluted and the other at Stidia is relatively healthy). A monthly sampling was carried out from January 2015 to December 2016. The sex ratio at the two sites is slightly in favour of males. Monthly monitoring of the gonad index showed maximum values during the month of May, and minimum values in September. The gonad index for both male and female evolves in the same way. Histological study of the male and the female gonads confirmed the results obtained for the gonad index. The sexual resting stage takes place in winter, followed by maturation in spring. Finally, the spawning phase occurs between spring and summer. The variability of the seasonal temperature values appears to influence the maturation of the gonads and the spawning process in A. lixula. The results obtained in this study show the existence of an annual cycle in A.lixula with the presence of a massive spawning in July, the duration of which depends on the combined effect of stress factors (increase in temperature and presence of pollution).

Chemical characterization of red cells from the black sea urchin Arbacia lixula by X-ray photoelectron spectroscopy.

Red spherula cells (RSC) from sea urchin coelomic fluid have attracted great interest for their specific and intriguing properties, such as for example antimicrobial activities and immune response, that probably tie in with their red characteristic pigments. Although to date different studies have been reported aimed to chemically characterize their pigments extracted from the cells, few data are available about the chemical characterization of the cell surface. In this work, a systematic chemical characterization of the RSC surface by X-ray photoelectron spectroscopy (XPS) analysis is described. The results were compared with data on colorless cells from the same coelomic fluid sample. Our observations evidenced that the two cell types were characterized by the presence of different chemical functional groups. In particular, the colorless cells are dominated by the presence of alkyl, alcohol, amide, and carboxyl groups in accordance with other similar cell types, enriched in Na+ and Cl− ions. Traces of elements like S (sulphonates) and P (phosphates) are also present. On the other hand, the RSC in addition to the alkyl groups show a reduction in the content of amide groups, accompanied by the anomalous presence of keto-enolic groups that probably can be associated with the presence of quinones/hydro-quinones from red pigments. A chemical enrichment in elements such as Cl− and Mg2+ and sulphate groups (–R–O–SO3−), as well as the presence of sulphides and phosphates traces, is evident. The absence of carbonate groups is also observed in both cell populations, confirming the absence of sodium and magnesium carbonate salts. No traces of toxic elements (i.e., heavy metals) have been revealed.

Temporal and spatial variability in the feeding behavior of the black sea urchin Arbacia lixula (Echinodermata: Echinoidea) from the north-western Algerian coast

The black sea urchin Arbacia lixula (Linnaeus, 1758) is one of the most domi-nant echinoids in the sublittoral communities of the Mediterranean Sea, where it is considered an essential structuring species by its grazing activity. The present work is considered to be the first study to address the diet of the species A. lixula in Algeria. This study aims to perform on the one hand; a temporal monitoring of the food preferences of two populations of A. lixula living in two different sites in shallow water (port of Salamandre, Stidia) on the coast of Mostaganem (Algeria) during the years 2015 and 2016, and on the other hand; get an idea of the variations of the different trophic sources used and appreciated by this echinoid. The quantitative and qualitative aspect is achieved by monitoring the evolution of the repletion index as well as the identification of the items present in the digestive contents by the contact method of Jones (1968). The results of this monitoring showed that it is an opportunistic species which adapts its diet according to the quality and quantity of food available. Arbacia lixula prefers encrusted coralline algae with a large faunal fraction. In areas rich in nutrients, the spines of these sea urchins may elongate to half the diameter of the test. Based on the results, A. lixula can be associated with habitat, seasonal changes or other specific environmental parameters that merit further development in order to fully understand its functioning in marine ecosystems.

Cell-Free Coelomic Fluid Extracts of the Sea Urchin Arbacia lixula Impair Mitochondrial Potential and Cell Cycle Distribution and Stimulate Reactive Oxygen Species Production and Autophagic Activity in Triple-Negative MDA-MB231 Breast Cancer Cells

Triple-negative breast cancer (TNBC) is a highly malignant tumor histotype which lacks effective targeted therapies, thereby being considered as the most aggressive form of breast carcinoma. To identify novel compounds which could counteract TNBC cell growth, we explored the in vitro effects of crude extracts and <10 kDa-filtered fractions of the coelomic fluid obtained from the sea urchin Arbacia lixula on TNBC MDA-MB231 cells. We examined cell viability, cycle distribution, apoptotic/autophagic activity, and mitochondrial polarization/cell redox status. Here, we report the first data demonstrating an anti-TNBC effect by A. lixula-derived coelomic fluid extracts. Thus, identification of the water-soluble bioactive component(s) contained in the extracts deserve(s) further investigation aimed to devise novel promising prevention and/or treatment agents effective against highly malignant breast tumors.

Responses of sea urchin larvae to field and laboratory acidification

Understanding the extent to which laboratory findings of low pH on marine organisms can be extrapolated to the natural environment is key toward making better projections about the impacts of global change on marine ecosystems. We simultaneously exposed larvae of the sea urchin Arbacia lixula to ocean acidification in laboratory and natural CO2 vents and assessed the arm growth response as a proxy of net calcification. Populations of embryos were simultaneously placed at both control and volcanic CO2 vent sites in Ischia (Italy), with a parallel group maintained in the laboratory in control and low pH treatments corresponding to the mean pH levels of the field sites. As expected, larvae grown at constant low pH (pHT 7.8) in the laboratory exhibited reduced arm growth, but counter to expectations, the larvae that developed at the low pH vent site (pHT 7.33–7.99) had the longest arms. The larvae at the control field site (pHT 7.87–7.99) grew at a similar rate to laboratory controls. Salinity, temperature, oxygen and flow regimes were comparable between control and vent sites; however, chlorophyll a levels and particulate organic carbon were higher at the vent site than at the control field site. This increased food availability may have modulated the effects of low pH, creating an opposite calcification response in the laboratory from that in the field. Divergent responses of the same larval populations developing in laboratory and field environments show the importance of considering larval phenotypic plasticity and the complex interactions among decreased pH, food availability and larval responses.

Effects of magnesium deprivation on development and biomineralization in the sea urchin Arbacia lixula

ABSTRACTEchinoderms have an extensive endoskeleton composed of magnesian calcite and occluded matrix proteins. As biomineralization in sea urchin larvae is sensitive to the Magnesium:Calcium ratio of seawater, we investigated the effects of magnesium deprivation on development and skeletogenesis in the sea urchin Arbacia lixula. We focused on the localization of the skeletogenic cells (primary mesenchyme cells) and the spatial expression of associated genes. Embryos reared in Mg-free seawater exhibited developmental delay from 6-h post-fertilization and at 24 h embryos showed complete lack of biomineral formation. Larvae (48–72 h) exhibited severe skeleton malformations. Fluorescent labelling revealed that the primary mesenchyme cells and the developing skeleton of treated embryos were in an abnormal ectopic location. Expression of the skeleton matrix protein gene (msp130) in the primary mesenchyme cells as seen using in situ hybridization was normal at 24 h. At 48 h this gene was down-regulated in control larvae, but not in treated larvae. Development of the pigment cells, immune cells that, like the skeleton, are mesodermal derivatives, was also impaired. Our results highlight the essential role of Mg in skeleton formation in sea urchin embryos with an indication that this element is also generally important for the development of mesoderm.Abbreviations: hpf: hours post fertilization; PMCs: primary mesenchyme cells; ACC: amorphous calcium carbonate; MgFSW: magnesium-free seawater; FSW: filtered seawaterImpact statementEchinoderms have an extensive endoskeleton composed of magnesian calciteWe investigated the effects of magnesium deprivation on development and skeletogenesis in the sea urchin Arbacia lixulaMagnesium deprivation caused developmental delay and skeleton malformationsPrimary mesenchyme cells of treated embryos were in an abnormal ectopic locationThe spatial and temporal expression profile of the skeleton matrix protein gene (msp130) was found to be different from controlsOur results highlight the essential role of Mg across developmental processes in sea urchin embryos.

Effect of sea urchin human harvest in promoting canopy forming algae restoration

The ability of species to recover from disturbance through natural recruitment is an important factor in determining the resilience of assemblages. The identification of patterns of resilience compatible or favoured by human activities has become a compelling need to address environmental management. In marine coastal systems, barrens are characterized by a dominance of encrusting calcareous algae and by high density of sea urchins and are considered an alternative stable state of systems collapsed due to overgrazing by sea urchins that originally were dominated by canopy-forming macroalga. Sea urchins also represent an important commercial resource, as some species are exploited worldwide. The present study aims at evaluating the effect of the harvesting of the sea urchin Paracentrotus lividus on promoting the shift from barren towards macroalgal beds. Three treatments were considered within a manipulative experiment in a Cystoseira-barren mixed habitat: natural sea urchins density, removal of all sea urchins and removal of only commercial P. lividus (natural density of the non-harvested sea urchin Arbacia lixula and juvenile P. lividus are maintained). Results showed that the removal of commercial P. lividus can promote Cystoseira recruitment. In fact, even if both A. lixula and juvenile P. lividus were present, the barren area decreased due to the spread of fleshy algae and the recruitment of the Cystoseira from the edge of vegetated patches. Therefore, removal of commercial P. lividus urchin is inferred as a reliable strategy to return ecosystems dominated by canopy-forming macroalgae.

Loving the warming: transcriptomic responses to acute thermal shifts in a recent colonizer in the Mediterranean, the sea urchin Arbacia lixula

Loving the warming: transcriptomic responses to acute thermal shifts in a recent colonizer in the Mediterranean, the sea urchin Arbacia lixula

Spatio-temporal patterns of genetic variation in Arbacia lixula, a thermophilous sea urchin in expansion in the Mediterranean.

The genetic structure of 13 populations of the amphiatlantic sea urchin Arbacia lixula, as well as temporal genetic changes in three of these localities, were assessed using ten hypervariable microsatellite loci. This thermophilous sea urchin is an important engineer species triggering the formation of barren grounds through its grazing activity. Its abundance seems to be increasing in most parts of the Mediterranean, probably favoured by warming conditions. Significant genetic differentiation was found both spatially and temporally. The main break corresponded to the separation of western Atlantic populations from those in eastern Atlantic and the Mediterranean Sea. A less marked, but significant differentiation was also found between Macaronesia (eastern Atlantic) and the Mediterranean. In the latter area, a signal of differentiation between the transitional area (Alboran Sea) and the rest of the Mediterranean was detected. However, no genetic structure is found within the Mediterranean (excluding Alboran) across the Siculo-Tunisian Strait, resulting from either enough gene flow to homogenize distance areas or/and a recent evolutionary history marked by demographic expansion in this basin. Genetic temporal variation at the Alboran Sea is as important as spatial variation, suggesting that temporal changes in hydrological features can affect the genetic composition of the populations. A picture of genetic homogeneity in the Mediterranean emerges, implying that the potential expansion of this keystone species will not be limited by intraspecific genetic features and/or potential impact of postulated barriers to gene flow in the region.

Food Modulation Controls Astaxanthin Accumulation in Eggs of the Sea Urchin Arbacia lixula.

The carotenoid astaxanthin has strong antioxidant properties with beneficial effects for various degenerative diseases. This carotenoid is produced by some microalgae species when cultivated in particular conditions, and, interestingly, it is a predominant carotenoid in aquatic animals throughout a broad range of taxa. Recently, astaxanthin was detected in the eggs of the sea urchin Arbacia lixula in relevant concentrations when this organism was maintained in culture. These results have paved the way for deeper research into astaxanthin production by this species, particularly in regards to how astaxanthin production can be modulated by diet. Results showed that the highest content of astaxanthin in eggs was observed in sea urchins fed on a diet enriched with Spirulina platensis. This result was confirmed by the high antioxidant activity recorded in the egg extracts of these animals. Our results suggest that (i) the sea urchin A. lixula is able to synthesize astaxanthin from precursors obtained from food, and (ii) it is possible to modulate the astaxanthin accumulation in sea urchin eggs by modifying the proportions of different food ingredients provided in their diet. This study demonstrates the large potential of sea urchin cultivation for the eco-sustainable production of healthy supplements for nutraceutical applications.

High genetic connectivity among morphologically differentiated populations of the black sea urchin Arbacia lixula (Echinoidea: Arbacioida) across the central African Mediterranean coast

The present study represents the first population structure analysis of the black sea urchin Arbacia lixula across part of its African Mediterranean distribution range, the Tunisian coast. This location is appropriate for the study of biogeographical processes given the presence of a well-known discontinuous biogeographic area (the Siculo-Tunisian Strait). Patterns of morphological and genetic variation in this highly dispersive echinoid species were assessed among its populations from the western and eastern Mediterranean coasts of Tunisia. A total of 109 specimens from six sites were collected and examined for morphometric variability in seven morphometric traits. Concordant results, inferred from CDA analyses, pairwise NPMANOVA comparisons and MDS plot, showed significant inter-population differences in the measured traits among the studied populations. In addition, UPGMA clustering and discriminant/Hotelling analysis enabled the delineation of two morphologically differentiated groups assigned to the western and eastern Mediterranean basins. SIMPER analysis showed that total dry weight and test diameter were major contributors to the morphometric separation between locations and among groups. Despite the extensive morphological variation found in A. lixula, genetic analysis of the mitochondrial COI marker recovered only a single evolutionary lineage and showed a lack of population structure as inferred from the results of one-level AMOVA and pairwise comparisons of genetic differentiation. Possible explanations for this genetic pattern are discussed. Notably, the lack of COI divergence patterns, highlighted by shallow genealogy associated with high haplotype diversity and low nucleotide diversity, together with a recent demographic expansion event retrieved from mismatch distribution and BSP analysis could be considered a residual effect of a recent evolutionary history of the species in the Mediterranean.

The Sea Urchin Arbacia lixula: A Novel Natural Source of Astaxanthin.

Several echinoderms, including sea urchins, are valuable sources of bioactive compounds but their nutraceutical potential is largely unexplored. In fact, the gonads of some sea urchin species contain antioxidants including carotenoids and polyhydroxylated naphthoquinones (PHNQ’s), such as echinochrome A. Astaxanthin is known to have particular bioactivity for the prevention of neurodegenerative diseases. This carotenoid is produced by microalgae, while several marine invertebrates can bioaccumulate or synthetize it from metabolic precursors. We determined the carotenoid content and analyzed the bioactivity potential of non-harvested Atlantic-Mediterranean sea urchin Arbacia lixula. The comparison of methanol crude extracts obtained from eggs of farmed and wild specimens revealed a higher bioactivity in farmed individuals fed with a customized fodder. HPLC-analysis revealed a high concentration of astaxanthin (27.0 μg/mg), which was the only pigment observed. This study highlights the potential of farmed A. lixula as a new source of the active stereoisomer of astaxanthin.