Review: Morphofunctional and biochemical markers of stress in sea urchin life stages exposed to engineered nanoparticles

Alterations induced by titanium dioxide nanoparticles (nano-TiO2) in fertilization and embryonic and larval development of the tropical sea urchin Lytechinus variegatus

The release of nanomaterials into the environment is the cause of an emerging concern. Titanium dioxide nanoparticles (nano-TiO₂) among the most produced nanomaterials, has been documented in marine coastal areas posing a threat on marine biota. Sea urchin embryos are recognized as suitable bioindicators in ecological risk assessment and recently for nanomaterials. This study investigated the impact of nano-TiO₂ on fertilization, embryonic and larval development of the tropical sea urchin Lytechinus variegatus in a range of concentrations (0.005-5 μg/mL) which includes environmentally relevant ones. The behavior of nano-TiO₂ in tropical natural seawater was determined by dynamic light scattering (DLS) and toxicity was evaluated through fertilization and embryotoxicity tests, and morphological/morphometric analyses of sea urchin's larvae. Limited toxicity was recorded for nano-TiO₂ in tropical sea urchin embryos and larvae, except for effects at the gastrula stage at 0.005 μg/mL. Large agglomerates of nano-TiO₂ (5 μg/mL) were observed adhering onto sea urchin larvae thus probably preventing nanoparticles uptake at the highest concentrations (>0.005 μg/mL). Environmental levels of nano-TiO₂ are able to cause toxicity on tropical sea urchin L. variegatus embryos with potential consequences on populations and their ecological role in tropical coastal areas.

Suspect Screening of Chemicals in Hospital Wastewaters Using Effect-Directed Analysis Approach as Prioritization Strategy

The increasing number of contaminants in the environment has pushed water monitoring programs to find out the most hazardous known and unknown chemicals in the environment. Sample treatment-simplification methods and non-target screening approaches can help researchers to not overlook potential chemicals present in complex aqueous samples. In this work, an effect-directed analysis (EDA) protocol using the sea urchin embryo test (SET) as a toxicological in vivo bioassay was used as simplified strategy to identify potential unknown chemicals present in a very complex aqueous matrix such as hospital effluent. The SET bioassay was used for the first time here to evaluate potential toxic fractions in hospital effluent, which were obtained after a two-step fractionation using C₁₈ and aminopropyl chromatographic semi-preparative columns. The unknown compounds present in the toxic fractions were identified by means of liquid chromatography coupled to a Q Exactive Orbitrap high-resolution mass spectrometer (LC-HRMS) and using a suspect analysis approach. The results were complemented by gas chromatography-mass spectrometry analysis (GC-MS) in order to identify the widest range of chemical compounds present in the sample and the toxic fractions. Using EDA as sample treatment simplification method, the number of unknown chemicals (>446 features) detected in the raw sample was narrowed down to 94 potential toxic candidates identified in the significantly toxic fractions. Among them, the presence of 25 compounds was confirmed with available chemical standards including 14 pharmaceuticals, a personal care product, six pesticides and four industrial products. The observations found in this work emphasize the difficulties in identifying potential toxicity drivers in complex water samples, as in the case of hospital wastewater.

Vanadium Modulates Proteolytic Activities and MMP-14-Like Levels during Paracentrotus lividus Embryogenesis

The increasing industrial use of vanadium (V), as well as its recent medical use in various pathologies has intensified its environmental release, making it an emerging pollutant. The sea urchin embryo has long been used to study the effects induced by metals, including V. In this study we used an integrated approach that correlates the biological effects on embryo development with proteolytic activities of gelatinases that could better reflect any metal-induced imbalances. V-exposure caused morphological/morphometric aberrations, mainly concerning the correct distribution of embryonic cells, the development of the skeleton, and the embryo volume. Moreover, V induced a concentration change in all the gelatinases expressed during embryo development and a reduction in their total proteolytic activity. The presence of three MMP-like gelatinases (MMP-2, -9, and -14) was also demonstrated and their levels depended on V-concentration. In particular, the MMP-14-like protein modified its expression level during embryo development in a time- and dose-dependent manner. This enzyme also showed a specific localization on filopodia, suggesting that primary mesenchyme cells (PMCs) could be responsible for its synthesis. In conclusion, these results indicate that an integrated study among morphology/morphometry, proteolytic activity, and MMP-14 expression constitutes an important response profile to V-action.

Amino-functionalized mesoporous silica nanoparticles (NH2-MSiNPs) impair the embryonic development of the sea urchin Paracentrotus lividus

Nanoparticles have found use in a wide range of applications, mainly as carriers of active biomolecules. It is thus necessary to assess their toxicity for human health, as well as for the environment, on which there is still a gap of knowledge. In this work, sea urchin Paracentrotus lividus, a widely used model for embryotoxicity and spermiotoxicity, has been used to assess potential detrimental effects of amino-functionalized mesoporous silica nanoparticles (NH₂-MSiNPs) on embryonic development. Specifically, gametes quality, embryogenesis morphological and timing alterations, and cellular stress markers, such as mitochondrial functionality, were assessed in presence of different concentrations of NH₂-MSiNPs in filtered seawater (FSW). Furthermore, dorsal-ventral axis development and skeletogenesis were characterized by microscopy imaging and gene expression analysis. NH₂-MSiNPs determined a strong reduction in the egg fertilization rate. Consequently, the presence of NH₂-MSiNPs resulted detrimental in P. lividus embryonic development, with severe morphological alterations correlated with an increased embryos mortality. Finally, NH₂-MSiNPs treatment was responsible for other toxic effects, such as reduced mitochondrial function and skeletogenesis alterations, according to the reduced mineralization sites in the endoskeleton formation and the related genes altered expression. Taken together, these results suggest the potential toxic effects of NH₂-MSiNPs on the marine ecosystem, with consequences for the development and reproduction of its organisms. Despite their promising potential as carriers of biomolecules, it is pivotal to consider that their uncontrolled use may result harmful to the environment and, consequently, to living organisms.

SETApp: A machine learning and image analysis based application to automate the sea urchin embryo test

Since countless xenobiotic compounds are being found in the environment, ecotoxicology faces an astounding challenge in identifying toxicants. The combination of high-throughput in vivo/in vitro bioassays with high-resolution chemical analysis is an effective way to elucidate the cause-effect relationship. However, these combined strategies imply an enormous workload that can hinder their implementation in routine analysis. The purpose of this study was to develop a new high throughput screening method that could be used as a predictive expert system that automatically quantifies the size increase and malformation of the larvae and, thus, eases the application of the sea urchin embryo test in complex toxicant identification pipelines such as effect-directed analysis. For this task, a training set of 242 images was used to calibrate the size-increase and malformation level of the larvae. Two classification models based on partial least squares discriminant analysis (PLS-DA) were built and compared. Moreover, Hierarchical PLS-DA shows a high proficiency in classifying the larvae, achieving a prediction accuracy of 84 % in validation. The scripts built along the work were compiled in a user-friendly standalone app (SETApp) freely accessible at https://github.com/UPV-EHU-IBeA/SETApp. The SETApp was tested in a real case scenario to fulfill the tedious requirements of a WWTP effect-directed analysis.

Exposure of adult sand dollars (Scaphechinus mirabilis) (Agassiz, 1864) to copper oxide nanoparticles induces gamete DNA damage

The increase in the number of products containing nanoparticles (NPs) poses a real threat to the environment. Recently, more evidence has been added to predictive models about the presence of NPs in various natural and anthropogenic systems. The acute toxicity of most aquatic NPs has now been well documented. However, data such as the ecotoxicological significance of the long-lasting effects of NPs on the reproductive system and gamete quality of aquatic organisms are still relatively scarce. Therefore, a 10-day experiment was carried out on the sand dollar Scaphechinus mirabilis (Agassiz, 1864) exposed to low (20 and 40 μg/L) concentrations of copper oxide nanoparticles (CuO NPs). An accumulation of copper in tissues and a significant increase in lipid peroxidation product concentrations after exposure to NP were observed. A significant decrease in the fertilization rate was shown at 40 μg/L. No significant changes in embryonic or larval development were found. However, comet analysis results showed a significant increase in DNA damage in spermatozoa exposed to CuO NPs, which may further manifest as negative effects at later developmental stages or in subsequent generations.

Individual and Binary Mixture Toxicity of Five Nanoparticles in Marine Microalga Heterosigma akashiwo

The investigation of the combined toxic action of different types of nanoparticles (NPs) and their interaction between each other and with aquatic organisms is an important problem of modern ecotoxicology. In this study, we assessed the individual and mixture toxicities of cadmium and zinc sulfides (CdS and ZnS), titanium dioxide (TiO₂), and two types of mesoporous silicon dioxide (with no inclusions (SMB3) and with metal inclusions (SMB24)) by a microalga growth inhibition bioassay. The counting and size measurement of microalga cells and NPs were performed by flow cytometry. The biochemical endpoints were measured by a UV-VIS microplate spectrophotometer. The highest toxicity was observed for SMB24 (EC50, 3.6 mg/L) and CdS (EC50, 21.3 mg/L). A combined toxicity bioassay demonstrated that TiO₂ and the SMB3 NPs had a synergistic toxic effect in combinations with all the tested samples except SMB24, probably caused by a “Trojan horse effect”. Sample SMB24 had antagonistic toxic action with CdS and ZnS, which was probably caused by metal ion scavenging.

Immunomodulatory Function of Polyvinylpyrrolidone (PVP)-Functionalized Gold Nanoparticles in Vibrio-Stimulated Sea Urchin Immune Cells

We investigated the role of the gold nanoparticles functionalized with polyvinylpyrrolidone (PVP–AuNPs) on the innate immune response against an acute infection caused by Vibrio anguillarum in an in vitro immunological nonmammalian next-generation model, the sea urchin Paracentrotus lividus. To profile the immunomodulatory function of PVP–AuNPs (0.1 μg mL⁻¹) in sea urchin immune cells stimulated by Vibrio (10 μg mL⁻¹) for 3 h, we focused on the baseline immunological state of the donor, and we analysed the topography, cellular metabolism, and expression of human cell surface antigens of the exposed cells, as well as the signalling leading the interaction between PVP–AuNPs and the Vibrio-stimulated cells. PVP–AuNPs are not able to silence the inflammatory signalling (TLR4/p38MAPK/NF-κB signalling) that involves the whole population of P. lividus immune cells exposed to Vibrio. However, our findings emphasise the ability of PVP–AuNPs to stimulate a subset of rare cells (defined here as Group 3) that express CD45 and CD14 antigens on their surface, which are known to be involved in immune cell maturation and macrophage activation in humans. Our evidence on how PVP–AuNPs may stimulate sea urchin immune cells represents an important starting point for planning new research work on the topic.

Development of alternative and sustainable methodologies in laboratory research on sea urchin gametes

The aim of the present work is to develop a laboratory-scaled methodology for an on-demand supply of semen from the sea urchin Paracentrotus lividus. Firstly, sea urchin specimens were acclimatized to the long-term rearing in a recirculating aquaculture system and gonad maturation was obtained under controlled conditions. Semen samples were then collected from mature sea urchins and cryopreserved. Finally, post-thawing motility was evaluated, to verify whether the cryopreserved semen had maintained enough viability to be used in laboratory activities. The post-thawing motility parameters remained quite unchanged for up to 60 min after activation; moreover, the semen even retained the ability of motility activation for 60 min after thawing. This motility pattern makes the use of cryopreserved semen a feasible option in spermiotoxicity bioassays. The preliminary ecotoxicity test, carried out using motility parameters as endpoints, showed sensitivity levels to cadmium falling in the same order of magnitude as those recorded for fresh sea urchin semen and for cryopreserved sea bream semen. . Therefore, semen samples produced and stored according to the developed methodology described in this paper, can be considered a promising and sustainable alternative to those collected from mature sea urchins harvested in the field.

Responses to iron oxide and zinc oxide nanoparticles in echinoderm embryos and microalgae: uptake, growth, morphology, and transcriptomic analysis

We investigated the toxicity of Iron oxide and Zinc oxide engineered nanoparticles (ENPs) on Paracentrotus lividus sea urchin embryos and three species of microalgae. Morphological responses, internalization, and potential impacts of Fe₂O₃ and ZnO ENPs on physiology and metabolism were assessed. Both types of ENPs affected P. lividus larval development, but ZnO ENPs had a much stronger effect. While growth of the alga Micromonas commoda was severely impaired by both ENPs, Ostreococcus tauri or Nannochloris sp. were unaffected. Transmission electron microscopy showed the internalization of ENPs in sea urchin embryonic cells while only nanoparticle interaction with external membranes was evidenced in microalgae, suggesting that marine organisms react in diverse ways to ENPs. Transcriptome-wide analysis in P. lividus and M. commoda showed that many different physiological pathways were affected, some of which were common to both species, giving insights about the mechanisms underpinning toxic responses.

Toxicity of Carbon, Silicon, and Metal-Based Nanoparticles to Sea Urchin Strongylocentrotus Intermedius

With the increasing annual production of nanoparticles (NPs), the risks of their harmful influence on the environment and human health are rising. However, our knowledge about the mechanisms of interaction between NPs and living organisms is limited. Prior studies have shown that echinoderms, and especially sea urchins, represent one of the most suitable models for risk assessment in environmental nanotoxicology. To the best of the authors’ knowledge, the sea urchin Strongylocentrotus intermedius has not been used for testing the toxicity of NPs. The present study was designed to determine the effect of 10 types of common NPs on spermatozoa activity, egg fertilization, and early stage of embryo development of the sea urchin S. intermedius. In this research, we used two types of multiwalled carbon nanotubes (CNT-1 and CNT-2), two types of carbon nanofibers (CNF-1 and CNF-2), two types of silicon nanotubes (SNT-1 and SNT-2), nanocrystals of cadmium and zinc sulfides (CdS and ZnS), gold NPs (Au), and titanium dioxide NPs (TiO₂). The results of the embryotoxicity test showed the following trend in the toxicity level of used NPs: Au > SNT-2 > SNT-1 > CdS > ZnS > CNF-2 > CNF-1 > TiO₂ > CNT-1 > CNT-2. This research confirmed that the sea urchin S. intermedius can be considered as a sensitive and stable test model in marine nanotoxicology.

Application of the Sea Urchin Embryo Test in Toxicity Evaluation and Effect-Directed Analysis of Wastewater Treatment Plant Effluents

Sea urchin embryo assay was used to assess general toxicity at four wastewater treatment plant effluents of Biscay (Gorliz, Mungia, Gernika, and Galindo), and within the tested range, all the extracts showed embryo growth inhibition and skeleton malformation activities with EC₅₀ values, in relative enrichment factor units, between 1.1-16.8 and 1.1-8.8, respectively. To identify the causative compounds, effect-directed analysis was successfully applied for the first time using a sea urchin embryo test to the secondary treatment of the Galindo effluent. To this end, two subsequent fractionation steps were performed using C18 (21 fractions) and aminopropyl columns (15 fractions). By this fractionation, the number of features detected by LC-HRMS in the raw sample was drastically reduced from 1500 to 9, and among them, two pesticides (mexacarbate, 17 ng/L, and fenpropidin, 23 ng/L), two antidepressants (amitriptyline, 304 ng/L, and paroxetine, 26 ng/L), and two anthelmintic agents (mebendazole, 65 ng/L, and albendazole, 48 ng/L) could be identified in the two toxic fractions. The artificial mixture of the identified six compounds could explain 79% of the observed effect, with albendazole and paroxetine as the predominant contributors (49% and 49%, respectively) affecting the sea urchin embryogenesis activity.

Toxicity of Carbon, Silicon, and Metal-Based Nanoparticles to the Hemocytes of Three Marine Bivalves

Simple Summary

The growing nanotechnology industry disposes of a variety of nanoparticles with different physiochemical properties in everyday life. However, the dependence of the safety and toxicity of nanoparticles on their physicochemical properties remains unclear. Bivalve molluscs represent an efficient model for the investigation of nanoparticle toxicity owing to their filtrating ability and feeding on particles suspended in the water. Moreover, the blood cells of bivalve molluscs, the hemocytes, have been suggested as a good analog test-object to mammalian immune cells, phagocytes. In this study, we used hemocytes of three marine bivalve species, namely, Crenomytilus grayanus, Modiolus modiolus, and Arca boucardi, to evaluate and compare the toxic effects of 10 different types of nanoparticles. We gave short-term exposure of the nanoparticles to the hemocytes and registered viability and changes in their cell membrane polarization by employing flow cytometry. Metal-based nanoparticles were the most toxic to the cells of all three tested bivalve mollusc species. However, the sensitivity to different nanoparticle types varied between species. Moreover, the registered cell membrane depolarization indicated an early toxic response and raised concern that chronic long-term exposure of nanoparticles (even if they were previously declared as safe) is a serious threat for aquatic organisms.

Abstract

Nanoparticles (NPs) have broad applications in medicine, cosmetics, optics, catalysis, environmental purification, and other areas nowadays. With increasing annual production of NPs, the risks of their harmful influence on the environment and human health are also increasing. Currently, our knowledge about the mechanisms of the interaction between NPs and living organisms is limited. The marine species and their habitat environment are under continuous stress owing to the anthropogenic activities, which result in the release of NPs in the aquatic environment. We used a bioassay model with hemocytes of three bivalve mollusc species, namely, Crenomytilus grayanus, Modiolus modiolus, and Arca boucardi, to evaluate the toxicity of 10 different types of NPs. Specifically, we compared the cytotoxic effects and cell-membrane polarization changes in the hemocytes exposed to carbon nanotubes, carbon nanofibers, silicon nanotubes, cadmium and zinc sulfides, Au-NPs, and TiO₂ NPs. Viability and the changes in hemocyte membrane polarization were measured by the flow cytometry method. The highest aquatic toxicity was registered for metal-based NPs, which caused cytotoxicity to the hemocytes of all the studied bivalve species. Our results also highlighted different sensitivities of the used tested mollusc species to specific NPs.

Developing Single Nucleotide Polymorphisms for Identification of Cod Products by RAD-Seq

The increase in the rate of seafood fraud, particularly in the expensive fishes, forces us to verify the identity of marine products. Meanwhile, the definition of cod lacks consistency at the international level, as few standards and effective application methods are capable of accurately detecting cod species. Genetic fingerprinting is important for both certifying authenticity and traceability of fish species. In this study, we developed a method that combines DNA barcoding and the restriction-site associated DNA sequencing (RAD-Seq) approach for the identification of cod products. We first obtained 6941 high-quality single nucleotide polymorphism (SNP)s from 65.6 gigabases (Gb) of RAD-Seq raw data, and two sequences that contain SNPs were finally used to successfully identify three different cod product species, which are Atlantic cod (Gadus morhua), Greenland turbot (Reinhardtius hippoglossoides), and Patagonian toothfish (Dissostichus eleginoides). This SNP-based method will help us to identify the products, which are sold under the name of "Xue Yu" (Cod) in China, and works in parallel with existing fish identification techniques to establish an efficient framework to detect and prevent fraud at all points of the seafood supply chain.

Role of Autophagy in Zinc Oxide Nanoparticles-Induced Apoptosis of Mouse LEYDIG Cells

Zinc oxide nanoparticles (ZnO NPs) have shown adverse health impact on the human male reproductive system, with evidence of inducing apoptosis. However, whether or not ZnO NPs could promote autophagy, and the possible role of autophagy in the progress of apoptosis, remain unclear. In the current study, in vitro and in vivo toxicological responses of ZnO NPs were explored by using a mouse model and mouse Leydig cell line. It was found that intragastrical exposure of ZnO NPs to mice for 28 days at the concentrations of 100, 200, and 400 mg/kg/day disrupted the seminiferous epithelium of the testis and decreased the sperm density in the epididymis. Furthermore, serum testosterone levels were markedly reduced. The induction of apoptosis and autophagy in the testis tissues was disclosed by up-regulating the protein levels of cleaved Caspase-8, cleaved Caspase-3, Bax, LC3-II, Atg 5, and Beclin 1, accompanied by down-regulation of Bcl 2. In vitro tests showed that ZnO NPs could induce apoptosis and autophagy with the generation of oxidative stress. Specific inhibition of autophagy pathway significantly decreased the cell viability and up-regulated the apoptosis level in mouse Leydig TM3 cells. In summary, ZnO NPs can induce apoptosis and autophagy via oxidative stress, and autophagy might play a protective role in ZnO NPs-induced apoptosis of mouse Leydig cells.

Cadmium stress effects indicating marine pollution in different species of sea urchin employed as environmental bioindicators

In recent years, researches about the defense strategies induced by cadmium stress have greatly increased, invading several fields of scientific research. Mechanisms of cadmium-induced toxicity continue to be of interest for researchers given its ubiquitous nature and environmental distribution, where it often plays the role of pollutant for numerous organisms. The presence in the environment of this heavy metal has been constantly increasing because of its large employment in several industrial and agricultural activities. Cadmium does not have any biological role and, since it cannot be degraded by living organisms, it is irreversibly accumulated into cells, interacting with cellular components and molecular targets. Cadmium is one of the most studied heavy metal inductors of stress and a potent modulator of several processes such as apoptosis, autophagy, reactive oxygen species, protein kinase and phosphatase, mitochondrial function, metallothioneins, and heat-shock proteins. Sea urchins (adults, gametes, embryos, and larvae) offer an optimal opportunity to investigate the possible adaptive response of cells exposed to cadmium, since these cells are known to accumulate contaminants. In this review, we will examine several responses to stress induced by cadmium in different sea urchin species, with a focus on Paracentrotus lividus embryos. The sea urchin embryo represents a suitable system, as it is not subjected to legislation on animal welfare and can be easily used for toxicological studies and as a bioindicator of environmental pollution. Recently, it has been included into the guidelines for the use and interpretation of assays to monitor autophagy.

Sea Urchin Embryo Model As a Reliable in Vivo Phenotypic Screen to Characterize Selective Antimitotic Molecules. Comparative evaluation of Combretapyrazoles, -isoxazoles, -1,2,3-triazoles, and -pyrroles as Tubulin-Binding Agents

A series of both novel and reported combretastatin analogues, including diarylpyrazoles, -isoxazoles, -1,2,3-triazoles, and -pyrroles, were synthesized via improved protocols to evaluate their antimitotic antitubulin activity using in vivo sea urchin embryo assay and a panel of human cancer cells. A systematic comparative structure-activity relationship studies of these compounds were conducted. Pyrazoles 1i and 1p, isoxazole 3a, and triazole 7b were found to be the most potent antimitotics across all tested compounds causing cleavage alteration of the sea urchin embryo at 1, 0.25, 1, and 0.5 nM, respectively. These agents exhibited comparable cytotoxicity against human cancer cells. Structure-activity relationship studies revealed that compounds substituted with 3,4,5-trimethoxyphenyl ring A and 4-methoxyphenyl ring B displayed the highest activity. 3-Hydroxy group in the ring B was essential for the antiproliferative activity in the diarylisoxazole series, whereas it was not required for potency of diarylpyrazoles. Isoxazoles 3 with 3,4,5-trimethoxy-substituted ring A and 3-hydroxy-4-methoxy-substituted ring B were more active than the respective pyrazoles 1. Of the azoles substituted with the same set of other aryl pharmacophores, diarylpyrazoles 1, 4,5-diarylisoxazoles 3, and 4,5-diaryl-1,2,3-triazoles 7 displayed similar strongest antimitotic antitubulin effect followed by 3,4-diarylisoxazoles 5, 1,5-diaryl-1,2,3-triazoles 8, and pyrroles 10 that showed the lowest activity. Introduction of the amino group into the heterocyclic core decreased the antimitotic antitubulin effect of pyrazoles, triazoles, and to a lesser degree of 4,5-diarylisoxazoles, whereas potency of the respective 3,4-diarylisoxazoles was increased.

Chronic toxicity of nanodiamonds can disturb development and reproduction of Acheta domesticus L

The use of nanodiamonds in numerous materials designed for industry and medicine is growing rapidly. Consequently health and environmental risks associated with the exposure of humans and other biota to nanodiamonds-based materials are of the utmost importance. Scarcity of toxicological data for these particles led us to examine the potentially deleterious effects of nanodiamonds in model insect species, Acheta domesticus (Orthoptera) chronically exposed to ND in its diet. Organism-level end-point indices (lifespan, body weight, consumption, caloric value of faeces, reproduction) revealed adverse changes in the treated crickets in comparison with the control. Preliminary studies of oxidative stress level in the offspring of ND-treated crickets suggest toxicity of these particles limited to the exposed individuals. EPR analysis showing increase of radical signal in the faeces of ND-fed crickets led us to propose novel mechanism of nanodiamonds toxicity that is discussed in the light of literature data.

CAPSULE

Development and reproduction of Acheta domesticus can be disturbed by the chronic exposure to nanodiamonds.

Cytotoxicity and genotoxicity of CuO nanoparticles in sea urchin spermatozoa through oxidative stress

Copper oxide nanoparticles (CuO NPs) are extensively used in various industrial and commercial applications. Despite their wide application may lead to the contamination of marine ecosystem, their potential environmental effects remain to be determined. Toxicity assessment studies have primarily focused on investigating the effects of CuO NPs on fertilization success and embryo development of different sea urchin species while the impact on sperm quality have never been assessed. In this line, this study aims to assess the effects of CuO NPs on the spermatozoa of the sea urchin Paracentrotus lividus. After sperm exposure to CuO NPs, biomarkers of sperm viability, cytotoxicity, oxidative stress, and genotoxicity as well as morphology were evaluated. Results showed that CuO NPs exposure decreased sperm viability, impaired mitochondrial activity and increased the production of reactive oxygen species (ROS) and lipid peroxidation. Furthermore, CuO NPs exposure caused DNA damage and morphological alterations. Together with the antioxidant rescue experiments, these results suggest that oxidative stress is the main driver of CuO NP spermiotoxic effects. The mechanism of toxicity is here proposed: the spontaneous generation of ROS induced by CuO NPs and the disruption of the mitochondrial respiratory chain lead to production of ROS that, in turn, induce lipid peroxidation and DNA damage, and result in defective spermatozoa up to induce sperm cytotoxicity. Investigating the effects of CuO NPs on sea urchin spermatozoa, this study provides valuable insights into the mechanism of reproductive toxicity induced by CuO NPs.

Long term exposure to low dose neurotoxic pesticides affects hatching, viability and cholinesterase activity of Artemia sp

The brine shrimp Artemia was used as a model organism to test toxicity of several neuroactive pesticides (chlorpyrifos (CLP), chlorpyrifos oxon (CLP ox), diazinon (DZN), carbaryl (CBR)) following exposure to far below than lethal doses. Cysts were exposed to the pesticides in order to test a scenario similar to actual coastal environment contamination, by analyzing different responses. Cysts were rehydrated in water containing the pesticides at concentrations ranging from 10^-11 to 10^-5 M, for 72, 96 and 192 h, respectively. For these exposure times, morpho-functional and biochemical parameters, such as hatching speed and viability were investigated in the larvae together with cholinesterase (ChE) activity quantification and histochemical localization. Finally, ChE inhibition was also compared with conventional selective ChE inhibitors. Results showed that CLP ox and CBR caused a significant dose-dependent decrease in hatching speed, followed by high percentages of larval death, while CLP and DZN were responsible for irregular hatching patterns. In addition, the pesticides mostly caused larval death some days post-hatching, whereas this effect was negligible for the specific ChE inhibitors, suggesting that part of pesticide toxicity may be due to molecules other than the primary target. ChE activity was observed in the protocerebrum lobes, linked to the development of pair eyes. Such activity was inhibited in larvae exposed to all pesticides. When compared to conventional selective inhibitors of ChE activities, this inhibition demonstrated that the selected pesticides mainly affect acetylcholinesterase and, to a lesser extent, pseudocholinesterases. In conclusion, the brine shrimp is a good model to test the environmental toxicity of long term exposure to cholinergic pesticides, since changes in hatching speed, viability and ChE activity were observed.