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• The toxicity of OlyA6/PlyB complex was assessed on the Mediterranean sea urchin. • OlyA6 was localized in the sea urchin egg containing sphingolipid membrane receptors. • High OlyA6/PlyB levels affected sea urchin fertilization and early development. • Delayed development and incorrect migration of primary mesenchyme cells occurred. • A slight environmental impact at high OlyA6/PlyB concentrations was found. The use of alternative solutions for pest management to replace pesticides in agriculture is of great interest. Proteinaceous complexes deriving from edible oyster mushrooms were recently proposed as environmentally friendly bioinsecticides. Such complexes, composed of ostreolysin A6 (OlyA6) and pleurotolysin B (PlyB), target invertebrate-specific membrane sphingolipids in insect's midgut, causing death through the formation of transmembrane pores. In this work, the potential impact of OlyA6/PlyB complexes was tested in the Mediterranean sea urchin Paracentrotus lividus, as an indicator of environmental quality. The ability of the fluorescently tagged OlyA6 to bind sea urchin gametes (sperm, eggs), the lipidome of sea urchin gametes, and the potential toxic effects and developmental anomalies caused by OlyA6/PlyB complexes on P. lividus early development (embryo, larvae) were investigated. The binding of the fluorescently tagged OlyA6 could be observed only in sea urchin eggs, which harbor OlyA6 sphingolipid membrane receptors, conversely to sperm. High protein concentrations affected sea urchin fertilization (>750 µg/L) and early development (> 375 µg/L in embryos; >100 µg/L in larvae), by causing toxicity and morphological anomalies in embryos and larvae. The main anomalies consisted in delayed embryos and incorrect migration of the primary mesenchyme cells that caused larval skeletal anomalies. The classification of these anomalies indicated a slight environmental impact of OlyA6/PlyB complexes at concentrations higher than 750 µg/L. Such impact should not persist in the marine environment, due to the reversible anomalies observed in sea urchin embryos and larvae that may promote defense strategies. However, before promoting the use of OlyA6/PlyB complexes as bio-pesticides at low concentrations, further studies on other marine coastal species are needed. [Display omitted] [ABSTRACT FROM AUTHOR]

The fate and toxicity of ingested marine microplastics (MPs) have been of major concern in aquatic ecotoxicology for the last decade. Although their ingestion by a wide range of marine organisms has been proven, the uptake of MPs within organs is not yet fully understood and relies on the ability of ingested microplastics to transfer from the gut to tissues beyond the digestive wall (i.e., translocation). The present study investigates the in vitro transfer of fluorescent high-density polyethylene particles of different sizes classes (1–5 µm; 10–29 µm; 38–45 µm) across the intestinal wall of the sea urchin Paracentrotus lividus using Ussing chambers. Small microplastics (1–5 µm) were proven to be able to cross the intestinal wall of P. lividus and reach the coelomic fluid, while larger microplastics (≥ 10 µm) were not observed to cross the intestinal wall. Results demonstrate a size-dependent passage of polyethylene microparticles across the intestinal walls of P. lividus for the first time, highlighting the suitability of Ussing chamber systems to study the transfer of MPs across the intestinal wall of animals. [ABSTRACT FROM AUTHOR]

• Transgenerational effects of OA were studied in P. lividus sperm and larvae. • Gametogenesis under OA resulted in increased sperm ATP content. • Slower decrease of swimming velocity was found in sperm from males kept at low pH. • Parental exposure to OA decreased larval survival but increased larval growth. • Parental pH affected offspring performances more than post-spawning pH. In marine organisms, differing degree of sensitivity to ocean acidification (OA) is expected for each life stage, and disturbance at one stage can carry over into the following stage or following generation. In this study we investigated phenotypic changes of sperm and larvae of the sea urchin Paracentrotus lividus in response to different pH conditions (8.0, 7.7, 7.4) experienced by the parents during gametogenesis. In sperm from two-months exposed males, sperm motility, velocity, ATP content, ATP consumption and respiration rate were evaluated at three pH values of the activating medium (8.0, 7.7 and 7.4). Moreover, larvae from each parental group were reared at pH 8.0 and 7.7 for 20 days and larval mortality and growth were then assessed. Sperm motility and respiration rate were not affected either by exposure of males to low pH or by the post-activation pH. Sperm velocity did not differ among post-activation pH values in all sperm groups, but it decreased slower in sperm developed under acidified conditions, suggesting the presence of positive carryover effect on sperm longevity. This positive carryover effect of exposure of males to low pH values was highlighted also for the sperm ATP content, which was higher in these groups of sperm. ATP consumption rate was affected by post-activation pH with higher values at pH 8.0 in sperm from males maintained at control condition and pH 7.7 while the energy consumption appeared to be differently modulated at different experimental conditions. A negative carry over effect of OA was observed on survival of larvae from parents acclimated at pH 7.4 and additive negative effects of both parental and larval exposure to low pH can be suggested. In all groups of larvae, decreased somatic growth was observed at low rearing pH, thus larvae from parents maintained at low pH did not show an increased capability to cope with OA. [ABSTRACT FROM AUTHOR]

We examined egg fertilisation in purple sea urchin ( Paracentrotus lividus ) after sperm exposure to carbon-based nanomaterials, carbon black (CB) and graphene oxide (GO), from 0.0001 mg/L to 1.0 mg/L. Gastrula stage embryos were investigated for acetylcholinesterase and propionylcholinesterase activities, and their morphological characteristics. Plutei were analysed for morphological abnormalities, with emphasis on skeletal rod formation. Egg fertilisation was significantly affected by CB, at all concentrations tested. Loss of cell adhesion at the gastrula surface was observed in eggs fertilised with sperm treated with CB. However, concentration-dependant morphological anomalies were observed in the gastrulae and plutei formed after sperm exposure to either CB or GO. The activities of both cholinesterases decreased in the gastrulae, although not in a concentration-dependent manner. These effects appear to arise from physical interactions between these carbon-based nanomaterials and the sperm, whereby nanomaterials attached to the sperm surface interfere with fertilisation, which leads to disturbances in the signalling pathways of early embryonic development. Reduced cholinesterase activity in gastrulae from eggs fertilised with nanomaterial-treated sperm confirms involvement of the cholinergic system in early sea urchin development, including skeletogenesis. [ABSTRACT FROM AUTHOR]

Usage of bisphenol A (BPA) in production of polycarbonate plastics has resulted in global distribution of BPA in the environment. These high concentrations cause numerous negative effects to the aquatic biota, among which the most known is the induction of endocrine disruption. The focus of this research was to determine the effects of two experimentally determined concentrations of BPA (100 nM and 4 μM) on cellular detoxification mechanisms during the embryonic development (2-cell, pluteus) of the rocky sea urchin ( Paracentrotus lividus ), primarily the potential involvement of multidrug efflux transport in the BPA intercellular efflux. The results of transport assay, measurements of the intracellular BPA and gene expression surveys, for the first time indicate the importance of P-glycoprotein (P-gp/ABCB1) in defense against BPA. Cytotoxic effects of BPA, validated by the immunohistochemistry (IHC) and the transmission electron microscopy (TEM), induced the aberrant karyokinesis, and consequently, the impairment of embryo development through the first cell division and retardation. [ABSTRACT FROM AUTHOR]

• Increased temperature enhanced development and arm length, Gd had a stunting effect. • Near-future temperature projections (+3 °C, 21 °C) reduced the negative effects of Gd. • Extreme warming (+6 °C, 24 °C) had negative synergistic effects. • Gd was the main driver for the induction of heat shock proteins expression. • Temperature, with or without Gd, induced the activation of autophagy and apoptosis. Gradual ocean warming and marine heatwaves represent major threats for marine organisms already facing other anthropogenic-derived hazards, such as chemical contamination in coastal areas. In this study, the combined effects of thermal stress and exposure to gadolinium (Gd), a metal used as a contrasting agent in medical imaging which enters the aquatic environment, were investigated in the embryos and larvae of the sea urchin Paracentrotus lividus. Embryos were exposed to six treatments of three temperatures (18 °C, 21 °C, 24 °C) and two Gd concentrations (control: 0 μM; treated: 20 μM). With respect to developmental progression, increased temperature accelerated development and achievement of the larval stage, while Gd-exposed embryos at the control temperature (18 °C) showed a general delay in development at 24 h post-fertilization (hpf), and a stunting effect and impaired skeleton growth at 48 hpf. Elevated temperatures at near-future projections (+3 °C, 21 °C) reduced the negative effects of Gd on development with a lower percentage of abnormality and improved skeleton growth. Combined extreme warming at present-day marine heatwave conditions (+6 °C, 24 °C) and Gd treatment resulted in a lower proportion of embryos reaching the advanced larval stages compared to the 21 °C + Gd. At the molecular level, western blot analysis showed that Gd was the main driver for the induction of heat shock protein (HSP60, HSP70) expression. At 48 hpf, temperature increase was the main driver for activation of additional cellular stress response strategies such as autophagy and apoptosis. Combined treatments showed the induction of HSP60 at 24 hpf and autophagic and apoptotic processes at 48 hpf. Treatments having low levels of HSPs expression showed high levels of apoptosis, and vice versa , clearly demonstrating the antagonistic effects of HSPs expression and apoptosis. Detection of fragmented DNA in apoptotic nuclei showed selective apoptosis, likely in extremely damaged cells. Our results indicate that the negative effects of Gd-exposure on P. lividus larval development and biomineralization will be mitigated by a near-future ocean warming, up to a thermotolerance threshold when negative synergistic effects were evident. Our data highlight the use of biomarkers as sensitive tools to detect environmental impacts as well as the need for a better understanding of the interactions between the multiple stressors faced by marine species in coastal environments. [ABSTRACT FROM AUTHOR]

• Zinc-sunscreens interfere with sea urchin skeletal formation and axial development. • Zinc-sunscreens are internalized by sea urchin embryos in a dose-dependent manner. • Exposure to sunscreens reduces sea urchin multidrug-resistant transporter activity. The growing popularity of physical sunscreens will lead to an increased release of ingredients from zinc oxide (ZnO) sunscreens into marine environments. Though zinc (Zn) is a necessary micronutrient in the ocean, greater than natural Zn concentrations may be released into marine environments by use of sunscreens. The extent of the consequences of this addition of Zn to the ocean are not fully understood. We investigated the effects of materials released by ZnO- sunscreens on the development of California purple sea urchin, Strongylocentrotus purpuratus. Embryos incubated in various concentrations of Zn (0.01, 0.05, 0.1, 0.5, and 1 mg/L), the sources of which included zinc-containing compounds: ZnO and zinc sulfate (ZnSO 4); and ZnO sunscreens: All Good, Badger, and Raw Elements brands. Based on EC 50 values, ZnO-containing sunscreens were slightly, but not significantly, more toxic than ZnO and ZnSO 4 , suggesting that sunscreens may release additional unknown materials that are detrimental to sea urchin embryo development. All concentrations of Zn-exposure resulted in significant malformations (skeletal abnormality, stage arrest, axis determination disruption), which were identified using light and fluorescence confocal microscopy. The concentration of Zn2+ internalized by the developing embryos correlated positively with the concentration of Zn in seawater. Additionally, exposure to both ZnO sunscreens and ZnO and ZnSO 4 at 1 mg/L Zn, significantly increased calcein-AM (CAM) accumulation, indicating decreased multidrug resistant (MDR) transporter activity. This is one of the first studies documenting ZnO-containing sunscreens release high concentrations of Zn that are internalized by and have detrimental effects on aquatic organisms. [ABSTRACT FROM AUTHOR]