Cadmium induces the expression of specific stress proteins in sea urchin embryos

Metallic trace element dynamics in Paracentrotus lividus from Algeria: Environmental large-scale survey and human health risk assessment

This paper evaluates the dynamics of Metallic Trace Elements (MTEs; Cd, Pb, Fe, Cu, Zn, Ni and Co) in the gonads of the sea urchin Paracentrotus lividus collected in five sites: four contaminated and one reference, along the Western coast of Algeria, recontextualizes this contamination within a wider geographical distribution area throughout 83 sites among the Mediterranean Sea and Atlantic and focuses on the potential risk of their consumption on human health for the first time in Algeria. The trace element pollution index places Algeria, and generally the North African coasts, as the region most contaminated by MTEs. The geographical variability in metal contamination levels is greater in the Mediterranean Sea than in the Atlantic. The health risk assessment indicates that Pb exceeds the maximum limit set by the Commission Regulation (EC) No 1881/2006 at two of the four Algerian contaminated sites.

Neurodegenerative Proteinopathies Induced by Environmental Pollutants: Heat Shock Proteins and Proteasome as Promising Therapeutic Tools

Environmental pollutants' (EPs) amount and diversity have increased in recent years due to anthropogenic activity. Several neurodegenerative diseases (NDs) are theorized to be related to EPs, as their incidence has increased in a similar way to human EPs exposure and they reproduce the main ND hallmarks. EPs induce several neurotoxic effects, including accumulation and gradual deposition of misfolded toxic proteins, producing neuronal malfunction and cell death. Cells possess different mechanisms to eliminate these toxic proteins, including heat shock proteins (HSPs) and the proteasome system. The accumulation and deleterious effects of toxic proteins are induced through HSPs and disruption of proteasome proteins' homeostatic function by exposure to EPs. A therapeutic approach has been proposed to reduce accumulation of toxic proteins through treatment with recombinant HSPs/proteasome or the use of compounds that increase their expression or activity. Our aim is to review the current literature on NDs related to EP exposure and their relationship with the disruption of the proteasome system and HSPs, as well as to discuss the toxic effects of dysfunction of HSPs and proteasome and the contradictory effects described in the literature. Lastly, we cover the therapeutic use of developed drugs and recombinant proteasome/HSPs to eliminate toxic proteins and prevent/treat EP-induced neurodegeneration.

Morphologic and genic effects of waste pollution on the reproductive physiology of Paracentrotus lividus lmk: a mesocosm experiment

A considerable amount of coastal contamination is caused by wastes deriving from household and the degradation and the metabolism of plants and animals, even if our attention is commonly focused on industrial pollutants and contaminants. Waste pollutants are mainly represented by highly diluted soluble compounds and particles deriving from dead organisms. This complex combination, consisting of suspended particles and dissolved nutrients, has a significant impact on coastal planktonic and benthic organisms, also playing an active role in the global cycles of carbon. In addition, production practices are nowadays shifting towards recirculated aquaculture systems (RAS) and the genic responses of target organisms to the pollution deriving from animal metabolism are still scarcely addressed by scientific investigations. The reservoir of organic matter dissolved in the seawater is by far the least understood if compared to that on land, cause only a few compounds have been identified and their impacts on animals and plants are poorly understood. The tendency of these compounds to concentrate at interfaces facilitates the absorption of dissolved organic compound (DOC) onto suspended particles. Some DOC components are chemically combined with dissolved metals and form complexes, affecting the chemical properties of the seawater and the life of the coastal biota. In this research, we compared the reproductive performances of the common sea urchin Paracentrotus lividus cultured in open-cycle tanks to those cultured in a recirculating aquaculture system (RAS), where pollution progressively increased during the experiment due to animal escretions. Sea urchins were cultured for 7 months under these two conditions and their gametes were collected. Embryos resulting by in vitro fertilization were analyzed by Real Time qPCR to identify possible effects of pollution-induced stress. The fertility of sea urchins was evaluated, as well as the gonadosomatic indices and the histological features of gonads. Our results indicate that pollution due to excess of nutrients, event at sub-lethal concentrations, may hardly impact the reproductive potential of this key species and that chronic effects of stress are revealed by the analyses of survival rates and gene expression.

Metallic trace element dynamics in Paracentrotus lividus from Algeria: Environmental and human health risk assessment

This paper evaluates the dynamic of Metallic Trace Elements (MTEs; Cd, Pb, Fe, Cu, Zn, Ni and Co) in the sea urchin Paracentrotus lividus collected in five sites: four contaminated and one reference, along the western coast of Algeria, recontextualizes this contamination within a wider geographical distribution area throughout 84 sites among the Mediterranean Sea and Atlantic and focuses on the potential risk on human health for the first time in Algeria. The Trace Element Pollution Index places Algeria, and generally the North African coasts, as the region most contaminated by MTEs. The Trace Element Spatial Variation Index ranks Pb as a MTE of key environmental concern according to global spatial variability. The health risk assessment indicates that Cd and Pb exceed the maximum limits set by the Commission Regulation (EC) No 1881/2006 on three of the four contaminated sites.

Assessing the eco-compatibility of new generation sunscreen products through a combined microscopic-molecular approach

There is now unequivocal evidence that sunscreen can severely affect marine ecosystems. However, so far, most studies have focused on the impact of single sunscreen ingredients rather than on the whole sunscreen products, which are released into the marine environment. In the present work, we investigated the ecological impact of six formulations, which represent the "new generation" organic UV filters such as diethylamino hydroxybenzoyl hexyl benzoate (DHHB), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), ethylhexyl triazone (EHT), and bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), which are progressively replacing the "old generation" organic UV filters (e.g., oxybenzone, octinoxate) banned in several countries of the world. The six formulations tested were characterized by a different combination of ingredients, on a model species particularly sensitive to environmental alterations: the sea urchin, Paracentrotus lividus. We investigated the sea urchin responses both in terms of gene expression and anomalies in embryonic development. We found that all sunscreen products containing only MBBT, DHHB, BEMT, and EHT as UV filters, are more eco-compatible than those also containing also ES, or other ingredients such as emollients and texturizing compounds, which may act synergistically causing molecular stress, morphological anomalies, and ultimately possible death. Overall, the results presented here provide new insights on the effects of sunscreen products based on "new generation" UV filters, and highlights the urgency of testing complete formulations, rather than just specific UV filters to ascertain the eco-compatibility of sunscreen products, to effectively minimize their impact on marine ecosystems.

Polymer aging affects the bioavailability of microplastics-associated contaminants in sea urchin embryos

Microplastics (MPs) in the marine environment undergo complex weathering factors that can affect their ability to interact with different coexisting environmental contaminants (termed here co-contaminants). In this study, the influence of artificially aging using UV on the sorption of a complex mixture of co-contaminants onto MPs was investigated in order to provide meaningful hypotheses on their individual and combined toxicities on sea urchin embryos. A mixture of artificially aged MPs (PS particles and PA microfibers) combined with 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), or Cd or Cu, both alone and in a mix, were used to expose embryos of Paracentrotus lividus. The effects of polymer aging on co-contaminants bioavailability were assessed by measuring changes in the transcriptional profile of genes involved in oxidative-stress response and skeletogenic and endo-mesodermal specification. Changes in the sorption ability of MPs to co-contaminants in the aqueous phase highlighted that aging did not affect the sorption of BDE-47 and Cd on MPs, although a certain influence on Cu sorption was found. Despite no morphological effects in embryos at the gastrula stage after MPs/contaminants combinatorial exposure emerged, the greatest influence of the aging process was mainly found for combined exposures which included BDE-47. Finally, the exposure to multiple contaminants generated transcriptional profiles poorly related to those activated by single contaminant, at times suggesting a mixture-dependent different aging influence. These results open new scenarios on the controversial role of vector of co-contaminants for MPs, especially when complex and different types of mixtures were considered.

Oligochaeta ramosa (Roxb.) Extract Regulates Lipid Metabolism and Exerts Hepatoprotective Effects in Cadmium-Induced Hepatic Injury in Rats

Environmental pollutants present a potential source of toxicity when exposed to humans. The study was aimed at investigating the potential of Oligochaeta ramosa (Roxb.) as a hepatoprotective agent in cadmium-induced hepatotoxicity causing lipid profile disturbance. The aqueous methanolic (30 : 70 v/v) extract of O. ramosa Roxb. (AME.Or) was subjected to preliminary phytochemical analysis, whereas the antioxidant activity of its constituents was investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The hepatoprotective and antihyperlipidemic effects of AME.Or was investigated by dividing animals into five groups (A-E). Animals were either treated with normal saline or CdCl₂ (6.5 mg/kg, intraperitoneally) followed by treatment with silymarin (100 mg/kg), or AME.Or (200 mg/kg) and AME.Or (400 mg/kg) for consecutive three weeks. Blood samples were collected, and the serum lipid profile was assessed on the 11^th and 21^st day of treatment. Histopathological analysis was performed after euthanization. In vitro analysis of AME.Or revealed 64% inhibition as free radicals scavenging potential during DPPH, total phenolic content (TPC) (79.92 mgGAE/g), and total flavonoids content (TFC) (38.75 mgRE/g). The group intoxicated with CdCl₂ showed significantly high (p ≤ 0.05) levels of the liver function indicators and lipid profile than in the control group. The higher dose of AME.Or (400 mg/kg) significantly decreased the aspartate aminotransferase (AST), alanine transferase (ALT), alkaline phosphatase (ALP), total bilirubin (p ≤ 0.001), decreased total cholesterol and triglycerides (p ≤ 0.01) while significantly increased high density lipoprotein (HDL; p ≤ 0.01) as compared to the intoxicated group. The histopathological analysis of the liver revealed signs of necrosis in the intoxicated group, while AME.Or treated groups showed marked improvement. The findings accentuate the therapeutic importance of O. ramosa (Roxb.) as a hepatoprotective remedy.

Stress response to trace elements mixture of different embryo-larval stages of Paracentrotus lividus

This study investigated for the first time the oxidative biomarkers responses in all larval stages of sea urchin. The contamination effects were reproduced by using contaminated seawater to concentrations measured in the area adjacent to an old asbestos mine at factors of 5 and 10. The results suggested that the concentrations were not sufficiently high to induce a major oxidative stress. The biometric differences make this method a more sensitive approach for assessing the effects on sea urchin larvae. Measurements of specific activities of antioxidant enzymes at each stage suggested a high capacity of the larvae to respond to oxidative stress. This normal activity of the organism must be considered in future research. This work also highlighted the importance of spawners provenance in ecotoxicological studies. These data are essential to better understand the stress responses of sea urchin larvae and provide baseline information for later environmental assessment research.

Effects of trace elements contaminations on the larval development of Paracentrotus lividus using an innovative experimental approach

Several experiments were performed using larvae of Paracentrotus lividus (Lamarck, 1816) in order to determine the consequences of different chronic contamination with mixtures of (i) fifteen trace elements from concentrations measured in the world ocean seawater, and (ii) seven trace elements from contamination resulting from mining. To predict the impact of increased marine pollution, higher concentrations were also used. These bioassays were conducted using spawners collected from Calvi (reference site, Corsica), and Albo (mining area, Corsica). The effects of trace elements have been studied on the entire larval development. The results show wider arms and delayed development as the number and concentration of trace elements increases. Therefore, the synergy between the different trace elements is of paramount importance with regard to the impact on organisms. Probably due to a hormesis phenomenon, larvae contaminated with seven trace elements at average concentrations developed more quickly. This work also highlighted the importance of the origin of spawners in ecotoxicological studies. To our knowledge, this is the first study to investigate the effects of such a broad combination of trace elements for chronic contamination on the entire larval stage of Paracentrotus lividus.

Exposure of adult sea urchin Strongylocentrotus intermedius to stranded heavy fuel oil causes developmental toxicity on larval offspring

Heavy fuel oil (HFO) spills pose serious threat to coastlines and sensitive resources. Stranded HFO that occurs along the coastline could cause long-term and massive damage to the marine environment and indirectly affect the survival of parental marine invertebrates. However, our understanding of the complex associations within invertebrates is primarily limited, particularly in terms of the toxicity effects on the offspring when parents are exposed to stranded HFO. Here, we investigated the persistent effects on the early development stage of the offspring following stranded HFO exposure on the sea urchin Strongylocentrotus intermedius. After 21 d exposure, sea urchins exhibited a significant decrease in the reproductive capacity; while the reactive oxygen species level, 3-nitrotyrosine protein level, protein carbonyl level, and heat shock proteins 70 expression in the gonadal tissues and gametes significantly increased as compared to the controls, indicating that HFO exposure could cause development toxicity on offspring in most traits of larval size. These results suggested that the stranded HFO exposure could increase oxidative stress of gonadal tissues, impair reproductive functions in parental sea urchins, and subsequently impact on development of their offspring. This study provides valuable information regarding the persistent toxicity effects on the offspring following stranded HFO exposure on sea urchins.

Lead in the marine environment: concentrations and effects on invertebrates

Lead (Pb) is a non-essential metal naturally present in the environment and often complexed with other elements (e.g., copper, selenium, zinc). This metal has been used since ancient Egypt and its extraction has grown in the last centuries. It has been used until recently as a fuel additive and is currently used in the production of vehicle batteries, paint, and plumbing. Marine ecosystems are sinks of terrestrial contaminations; consequently, lead is detected in oceans and seas. Furthermore, lead is not biodegradable. It remains in soil, atmosphere, and water inducing multiple negative impacts on marine invertebrates (key species in trophic chain) disturbing ecological ecosystems. This review established our knowledge on lead accumulation and its effects on marine invertebrates (Annelida, Cnidaria, Crustacea, Echinodermata, and Mollusca). Lead may affect different stages of development from fertilization to larval development and can also lead to disturbance in reproduction and mortality. Furthermore, we discussed changes in the seawater chemistry due to Ocean Acidification, which can affect the solubility, speciation, and distribution of the lead, increasing potentially its toxicity to marine invertebrates.

Four plastic additives reduce larval growth and survival in the sea urchin Strongylocentrotus purpuratus

Plastic additives are utilized during the production of plastic to modify the attributes and stability of the polymer. As oceanic plastic waste degrades, these additives can leach, and are harmful to global marine ecosystems. Despite the high abundance of additives leached into the marine environment, little is known about their direct impact on marine zooplankton. Here we test for impacts of four plastic additives, UV-327, Irganox 1010, DEHP, and methylparaben, all commonly used in plastic manufacturing, on purple sea urchin (Strongylocentrotus purpuratus) larval growth and survival in a serial dose response for 4 days. Methylparaben, UV-327, and Irganox 1010 significantly reduced larval body length by about 5% for at least one dose. In contrast, all compounds reduced larval survival by 20-70% with strongest effects at intermediate rather than high doses. Our results highlight that plastic additives should be tested for their effects on marine organisms.

Toxic effects induced by vanadium on sea urchin embryos

Vanadium, a naturally occurring element widely distributed in soil, water and air, has received considerable interest because its compounds are often used in different applications, from industry to medicine. While the possible medical use of vanadium compounds is promising, its potential harmful effects on living organisms are still unclear. Here, for the first time, we provide a toxicological profile induced by vanadium on Paracentrotus lividus sea urchin embryos, reporting an integrated and comparative analysis of the detected effects reflecting vanadium-toxicity. At the morphological level we found a dose-dependent induction of altered phenotypes and of skeletal malformations. At the molecular levels, vanadium-exposed embryos showed the activation of the cellular stress response, in particular, autophagy and a high degree of cell-selective apoptosis in a dose-dependent manner. The stress response mediated by heat shock proteins seems to counteract the damage induced by low and intermediate concentrations of vanadium while the high cytotoxic concentrations induce more marked cell death mechanisms. Our findings, reporting different mechanisms of toxicity induced by vanadium, contribute to increase the knowledge on the possible threat of vanadium for marine organisms and for both environmental and human health.

Gene Expression Changes after Parental Exposure to Metals in the Sea Urchin Affect Timing of Genetic Programme of Embryo Development

It is widely accepted that phenotypic traits can be modulated at the epigenetic level so that some conditions can affect the progeny of exposed individuals. To assess if the exposure of adult animals could result in effects on the offspring, the Mediterranean sea urchin and its well-characterized gene regulatory networks (GRNs) was chosen as a model. Adult animals were exposed to known concentrations of zinc and cadmium (both individually and in combination) for 10 days, and the resulting embryos were followed during the development. The oxidative stress occurring in parental gonads, embryo phenotypes and mortality, and the expression level of a set of selected genes, including members of the skeletogenic and endodermal GRNs, were evaluated. Increased oxidative stress at F₀, high rates of developmental aberration with impaired gastrulation, in association to deregulation of genes involved in skeletogenesis (dri, hex, sm50, p16, p19, msp130), endodermal specification (foxa, hox11/13b, wnt8) and epigenetic regulation (kat2A, hdac1, ehmt2, phf8 and UBE2a) occurred either at 24 or 48 hpf. Results strongly indicate that exposure to environmental pollutants can affect not only directly challenged animals but also their progeny (at least F₁), influencing optimal timing of genetic programme of embryo development, resulting in an overall impairment of developmental success.

Interactive effects of increased temperature and gadolinium pollution in Paracentrotus lividus sea urchin embryos: a climate change perspective

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.

Influence of environmentally relevant concentrations of Zn, Cd and Ni and their binary mixtures on metal uptake, bioaccumulation and development in larvae of the purple sea urchin Strongylocentrotus purpuratus

Metal accumulation, disturbance of Ca²⁺ homeostasis, and occurrence of abnormalities are well-established consequences of single metal exposure during early development stages of sea urchins. However, the effects caused by low concentrations of metals and metal mixtures need to be better understood in marine invertebrates. Therefore, the present study investigated the effects of environmentally relevant concentrations of Zn (9 μg/L), Cd (30 μg/L) and Ni (5 μg/L) in single and binary exposures (Zn + Cd, Cd + Ni and Ni + Zn) to the early life stages of the purple sea urchin Strongylocentrotus purpuratus. Endpoints checked in all treatments after 48-h exposure were unidirectional metal influx rates, bioaccumulation, and Ca²⁺ influx rates. Additionally, the presence of abnormal larvae and developmental delay was evaluated at 24 h, 48 h and 72 h of exposure. Unidirectional influx rates of all three metals were significantly higher than control background rates in all single exposures and binary mixtures, and were generally not different between them. Net accumulation (body burden) of both Zn and Cd increased significantly as a result of their respective single exposures, while Ni accumulation decreased considerably. When Zn or Cd were presented in binary exposures with other metals, the net accumulations of Zn or Cd were reduced relative to single exposures to these metals, whereas this did not occur for Ni accumulation. Thus, bioaccumulation proved to be a better metric than influx rate measurements to analyze metal competition at a whole organism level at these low metal concentrations. Short-term Ca²⁺ influx also did not appear to be a sensitive metric, as the measured rates did not vary among all single and binary exposures, with the exception of a lower rate in Ni + Zn binary exposure. A critical aspect observed was the relationship between bioaccumulation versus influx measurements, which proved positive for Cd, but negative for Zn and Ni, demonstrating possible capacities for both Zn and Ni regulation by sea urchin larvae. Increases in larval abnormalities relative to controls occurred only after binary mixtures, starting at 48 h exposure and maintained until 72 h. However, delay of the sea urchin development by the presence of gastrula stage at 72 h exposure occurred in Zn and Ni single exposures and all metal mixtures, with very high abnormal development when Ni was present.

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.

Assessment and Monitoring of Fish Quality from a Coastal Ecosystem under High Anthropic Pressure: A Case Study in Southern Italy

Fish is a nutrient-rich food but, at the same time, consumption of fish is a possible source of exposure to heavy metals. Since many coastal Mediterranean areas suffer from great anthropomorphic pressure, the aim of this study was to assess the level of potentially toxic inorganic elements in different fish samples from the coastal zone of Southern Italy (Gela) where there is a high mortality rate linked to cancer disease and congenital malformations. The presence of mercury, cadmium, lead, nickel, arsenic, vanadium, and chromium was measured by inductively coupled plasma-mass spectrometry (ICP-MS). The risk assessment was evaluated in terms of estimated daily intake by calculating the amount of potentially toxic elements that an average individual adult weighing 60 kg would ingest. Moreover the non-carcinogenic risk was estimated by target hazard quotient (THQ). The study evidenced significant contamination by inorganic elements, especially cadmium, which can be linked to industrial pollution. The THQ indexes, as indicators of human health, suggest that the consumption of fish from the study area is not free of risk.

Effects of elevated temperature on gonadal functions, cellular apoptosis, and oxidative stress in Atlantic sea urchin Arbacia punculata

Increasing seawater temperature affects growth, reproduction and development in marine organisms. In this study, we examined the effects of elevated temperatures on reproductive functions, heat shock protein 70 (HSP70) and nitrotyrosine protein (NTP, an indicator of reactive nitrogen species) expressions, protein carbonyl (PC, an indicator of oxidative stress) contents, cellular apoptosis, and coelomic fluid (CF) conditions in Atlantic sea urchin. Sea urchins were housed in six aquaria with control (24 °C) and elevated temperatures (28 °C and 32 °C) for a 7-day period. After exposure, sea urchins exhibited decreased percentages of gametes (eggs/sperm), as well as increased HSP70 and NTP expressions in eggs and spermatogenic cells, increased gonadal apoptosis, and decreased CF pH compared to controls. PC contents were also significantly increased in gonadal tissues at higher temperatures. These results suggest that elevated temperature acidifies CF, increases oxidative stress and gonadal apoptosis, and results in impairment of reproductive functions in sea urchins.

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.

Ocean acidification modulates the incorporation of radio-labeled heavy metals in the larvae of the Mediterranean sea urchin Paracentrotus lividus

The marine organisms which inhabit the coastline are exposed to a number of anthropogenic pressures that may interact. For instance, the accumulation of toxic metals present in coastal waters is expected to be modified by ocean acidification through e.g. changes in physiological performance and/or elements availability. Changes in bioaccumulation due to lowering pH are likely to be differently affected depending on the nature (essential vs. non-essential) and speciation of each element. The Mediterranean is of high concern for possible cumulative effects due to strong human influences on the coastline. The aim of this study was to determine the effect of ocean acidification (from pH 8.1 down to -1.0 pH units) on the incorporation kinetics of six trace metals (Mn, Co, Zn, Se, Ag, Cd, Cs) and one radionuclide (²⁴¹Am) in the larvae of an economically- and ecologically-relevant sea urchin of the Mediterranean coastline: Paracentrotus lividus. The radiolabelled metals and radionuclides added in trace concentrations allowed precise tracing of their incorporation in larvae during the first 74 h of their development. Independently of the expected indirect effect of pH on larval size/developmental rates, Paracentrotus lividus larvae exposed to decreasing pHs incorporated significantly more Mn and Ag and slightly less Cd. The incorporation of Co, Cs and ²⁴¹Am was unchanged, and Zn and Se exhibited complex incorporation behaviors. Studies such as this are necessary prerequisites to the implementation of metal toxicity mitigation policies for the future ocean. We discuss possible reasons and mechanisms for the specific effect of pH on each metals.

Cadmium alters heat shock protein pathways in SN56 cholinergic neurons, leading to Aβ and phosphorylated Tau protein generation and cell death

Cadmium, a neurotoxic environmental compound, produces cognitive disorders, although the mechanism remains unknown. Cadmium induces a more pronounced cell death on cholinergic neurons from basal forebrain (BF), mediated, in part, by increase in Aβ and total and phosphorylated Tau protein levels, which may explain cadmium effects on learning and memory processes. Cadmium downregulates the expression of heat shock proteins (HSPs) HSP 90, HSP70 and HSP27, and of HSF1, the master regulator of the HSP pathway. HSPs proteins reduce the production of Aβ and phosphorylated Tau proteins and avoid cell death pathways induction. Thus, we hypothesized that cadmium induced the production of Aβ and Tau proteins by HSP pathway disruption through HSF1 expression alteration, leading to BF cholinergic neurons cell death. Our results show that cadmium downregulates HSF1, leading to HSP90, HSP70 and HSP27 gene expression downregulation in BF SN56 cholinergic neurons. In addition, cadmium induced Aβ and total and phosphorylated Tau proteins generation, mediated partially by HSP90, HSP70 and HSP27 disruption, leading to cell death. These results provide new understanding of the mechanisms contributing to cadmium harmful effects on cholinergic neurons.

Effects of Boron Supplementation on Expression of Hsp70 in the Spleen of African Ostrich

Increased synthesis of heat shock protein 70 (Hsp70) occurs in prokaryotes and eukaryotes in response to physiological, environmental, and chemical exposures, thus allowing the cell survival from fatal conditions. Hsp70 cytoprotective properties may be clarified by its anti-apoptotic function. Boron has been reported to play an essential role in various organ developments and metabolisms. However, it is not known if boron is also able to modulate the Hsp70. In the present study, the actions of boron on ostrich spleen and expression level of Hsp70 were investigated. Thirty healthy ostrich chicks were randomly assigned to six groups: groups I, II, III, IV, V, and VI and fed the basal diet spiked with 0-, 40-, 80-, 160-, 320-, and 640-mg boric acid (BA)/L, respectively, in drinking water. The histomorphological examination in the spleen was done by hematoxylin and eosin (HE) staining. The expression level of Hsp70 was analyzed by immunohistochemistry (IHC) and western blotting, and mRNA expression of Hsp70 was investigated by quantitative real-time PCR (qPCR). In order to investigate apoptosis, TUNEL assay reaction in all treatment groups was analyzed. Our results showed that the histological structure of spleen up to 160 mg/L BA supplementation groups well developed. The Hsp70 expression level first induced at low-dose groups (up to group IV) and then inhibited dramatically in high-dose groups (V and VI) while comparing with the group I (0 mg BA). The TUNEL assay reaction revealed that the cell apoptosis amount was decreased in group IV, but in group V and especially in group VI, it was significantly increased (P < 0.01). Taken altogether, proper dietary boron treatment might stimulate ostrich chick spleen development by promoting the Hsp70 expression level and inhibiting apoptosis, while a high amount of boron supplementation would impair the ostrich spleen structure by inhibiting Hsp70 expression level and promoting cell apoptosis.

The role of the p38-activated protein kinase signaling pathway-mediated autophagy in cadmium-exposed monogonont rotifer Brachious koreanus

Autophagy is a 'self-eating' system that regulates the degradation of cellular components and is involved in various biological processes including survival and development. However, despite its crucial role in organisms, the regulatory mechanism of autophagy remains largely unclear, particularly in invertebrates. In this study, conserved autophagy in the rotifer Brachionus koreanus in response to cadmium (Cd) exposure was verified by measuring acidic vesicle organelles using acridine orange (AO) and neutral red (NR) staining, and by detecting LC3 I/II on Western blot and immunofluorescence. We also demonstrated activation of p38 mitogen-activated protein kinase (MAPK) in response to Cd-induced oxidative stress, leading to the induction of autophagy in B. koreanus. This was further verified by analysis of MAPK protein levels and immunofluorescence of LC3 I/II after treatment with reactive oxygen species (ROS) scavengers and inhibitors specific to MAPKs. We propose a p38 MAPK-mediated regulatory mechanism of autophagy in B. koreanus in response to Cd-induced oxidative stress. This study will contribute to a better understanding of autophagic processes in invertebrates and its modulation by environmental stressors.

Selenium antagonizes cadmium-induced apoptosis in chicken spleen but not involving Nrf2-regulated antioxidant response

The nuclear transcription factor NF-E2-related factor 2 (Nrf2) binds to antioxidant response elements (AREs) and is involved in the regulation of genes participated in defending cells against oxidative damage, which have been confirmed in animal models. Selenium (Se), known as an important element in the regulation of antioxidant activity, can antagonize Cadmium (Cd) toxicity in birds. However, the role of Nrf2 in selenium-cadmium interaction has not been reported in birds. To further explore the mechanism of selenium attenuating spleen toxicity induced by cadmium in chickens, cadmium chloride (CdCl₂, 150mg/kg) and sodium selenite (Na₂SeO₃, 2mg/kg) were co-administrated or individually administered in the diet of chickens for 90 days. The results showed that Cd exposure increased the level of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) and decreased the antioxidant enzyme activities, including superoxide dismutase (SOD), glutathione peroxidase (Gpx), total antioxidative capacity (T-AOC), catalase (CAT). Cd exposure increased obviously nuclear accumulation of Nrf2, and the expression of Nrf2 downstream heme oxygenase-1 (HO-1) and NAD(P)H: quinine oxidoreductase 1 (NQO1), reduced the expression of Kelch-like ECH-associated protein (keap1), Gpx-1 and thioredoxin reductase-1 (TrxR1). In addition, Cd induced the increase of bak, caspase9, p53, Cyt c mRNA levels, increased bax/bcl-2 ratio, increased caspase3 mRNA and protein levels. Selenium treatment reduced the accumulation of Cd in the spleen, attenuates Cd-induced Nrf2 nuclear accumulation, enhanced antioxidant enzyme activities, ameliorated Cd-induced oxidative stress and apoptosis in the spleen. In summary, our results demonstrate that Se ameliorated spleen toxicity induced by cadmium by modulating the antioxidant system, independently of Nrf2-regulated antioxidant response pathway.

Induction of skeletal abnormalities and autophagy in Paracentrotus lividus sea urchin embryos exposed to gadolinium

Gadolinium (Gd) concentration is constantly increasing in the aquatic environment, becoming an emergent environmental pollutant. We investigated the effects of Gd on Paracentrotus lividus sea urchin embryos, focusing on skeletogenesis and autophagy. We observed a delay of biomineral deposition at 24 hours post fertilization (hpf), and a strong impairment of skeleton growth at 48 hpf, frequently displayed by an asymmetrical pattern. Skeleton growth was found partially resumed in recovery experiments. The mesodermal cells designated to biomineralization were found correctly migrated at 24 hpf, but not at 48 hpf. Western blot analysis showed an increase of the LC3-II autophagic marker at 24 and 48 hpf. Confocal microscopy studies confirmed the increased number of autophagolysosomes and autophagosomes. Results show the hazard of Gd in the marine environment, indicating that Gd is able to affect different aspects of sea urchin development: morphogenesis, biomineralization, and stress response through autophagy.

Coexposure to sulfamethoxazole and cadmium impairs development and attenuates transcriptional response in sea urchin embryo

Among sulfonamides, sulfamethoxazole represents one of the most widely employed. A considerable amount of sulfamethoxazole is introduced into the marine environment after utilization in aquaculture. The cytotoxicity of sulfamethoxazole relies mainly on arylhydroxylamine metabolites and it is associated with the production of reactive oxygen species. Cadmium represents a metal largely employed in several anthropic activities and it is toxic for all living organisms even at low concentrations. Since it is not degraded, cadmium irreversibly accumulates into cells. In order to understand the mechanisms of response to changes in the chemical environment, we investigated by light microscopy observations and RT-qPCR assays the impact of sulfamethoxazole and cadmium in P. lividus sea urchin embryos. During development, embryos were exposed to sulfamethoxazole amount comparable to that usually used in aquaculture procedures and/or sublethal levels of cadmium chloride. Impairment of development and biomarkers for inflammation, detoxification, metal scavenging and cell death were inspected. Even though treatment with sulfamethoxazole apparently did not affect development, it stimulated a remarkable molecular response to oxidative stress. Moreover, combined exposure seriously compromised development and the defense mechanisms to cadmium were blocked. This study leads to the conclusion that coexposure to sulfamethoxazole and cadmium induces neutralizing effects on sea urchin embryos. Thus, in marine areas nearby aquaculture farms, where sulfamethoxazole discharge represents an important environmental contaminant, cadmium occurrence may alter population dynamics of P. lividus.

Overview of the molecular defense systems used by sea urchin embryos to cope with UV radiation

The sea urchin embryo is a well-recognized developmental biology model and its use in toxicological studies has been widely appreciated. Many studies have focused on the evaluation of the effects of chemical stressors and their mixture in marine ecosystems using sea urchin embryos. These are well equipped with defense genes used to cope with chemical stressors. Recently, ultraviolet radiation (UVR), particularly UVB (280-315 nm), received more attention as a physical stressor. Mainly in the Polar Regions, but also at temperate latitudes, the penetration of UVB into the oceans increases as a consequence of the reduction of the Earth's ozone layer. In general, UVR induces oxidative stress in marine organisms affecting molecular targets such as DNA, proteins, and lipids. Depending on the UVR dose, developing sea urchin embryos show morphological perturbations affecting mainly the skeleton formation and patterning. Nevertheless, embryos are able to protect themselves against excessive UVR, using mechanisms acting at different levels: transcriptional, translational and post-translational. In this review, we recommend the sea urchin embryo as a suitable model for testing physical stressors such as UVR and summarize the mechanisms adopted to deal with UVR. Moreover, we review UV-induced apoptotic events and the combined effects of UVR and other stressors.

Effects of exposure to gadolinium on the development of geographically and phylogenetically distant sea urchins species

Gadolinium (Gd), a metal of the lanthanide series used as contrast agent for magnetic resonance imaging, is released into the aquatic environment. We investigated the effects of Gd on the development of four sea urchin species: two from Europe, Paracentrotus lividus and Arbacia lixula, and two from Australia, Heliocidaris tuberculata and Centrostephanus rodgersii. Exposure to Gd from fertilization resulted in inhibition or alteration of skeleton growth in the plutei. The similar morphological response to Gd in the four species indicates a similar mechanism underlying abnormal skeletogenesis. Sensitivity to Gd greatly varied, with the EC50 ranging from 56 nM to 132 μM across the four species. These different sensitivities highlight the importance of testing toxicity in several species for risk assessment. The strong negative effects of Gd on calcification in plutei, together with the plethora of marine species that have calcifying larvae, indicates that Gd pollution is urgent issue that needs to be addressed.

Recombinant heat shock protein 27 (HSP27/HSPB1) protects against cadmium-induced oxidative stress and toxicity in human cervical cancer cells

Cadmium (Cd) is a carcinogen with several well-described toxicological effects in humans, but its molecular mechanisms are still not fully understood. Overexpression of heat shock protein 27 (HSP27/HSPB1)-a multifunctional protein chaperone-has been shown to protect cells from oxidative damage and apoptosis triggered by Cd exposure. The aims of this work were to investigate the potential use of extracellular recombinant HSP27 to prevent/counteract Cd-induced cellular toxicity and to evaluate if peroxynitrite was involved in the development of Cd-induced toxicity. Here, we report that the harmful effects of Cd correlated with changes in oxidative stress markers: upregulation of reactive oxygen species, reduction in nitric oxide (NO) bioavailability, increment in lipid peroxidation, peroxynitrite (PN), and protein nitration; intracellular HSP27 was reduced. Treatments with Cd (100 μM) for 24 h or with the peroxynitrite donor, SIN-1, decreased HSP27 levels (~50%), suggesting that PN formation is responsible for the reduction of HSP27. Pre-treatments of the cells either with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) (a pharmacological inhibitor of NO synthase) or with recombinant HSP27 (rHSP27) attenuated the disruption of the cellular metabolism induced by Cd, increasing in a 55 and 52%, respectively, the cell viability measured by CCK-8. Cd induced necrotic cell death pathways, although apoptosis was also activated; pre-treatment with L-NAME or rHSP27 mitigated cell death. Our findings show for the first time a direct relationship between Cd-induced toxicity and PN production and a role for rHSP27 as a potential therapeutic agent that may counteract Cd toxicity.

Autophagy is required for sea urchin oogenesis and early development

Autophagy is a major intracellular pathway for the degradation and recycling of cytosolic components. Emerging evidence has demonstrated its crucial role during the embryo development of invertebrates and vertebrates. We recently demonstrated a massive activation of autophagy in Paracentrotus lividus embryos under cadmium stress conditions, and the existence of a temporal relationship between induced autophagy and apoptosis. Although there have been numerous studies on the role of autophagy in the development of different organisms, information on the autophagic process during oogenesis or at the start of development in marine invertebrates is very limited. Here we report our recent data on the occurrence of autophagy at these key phases of development. In order to investigate autophagy trends we performed in vivo assays to detect autophagolysomes, as well as in situ analysis with anti-LC3 antibody to detect autophagosomes before the fusion with lysosomes. From data generated through confocal laser scanning microscopy and quantification of autophagic signals we have drawn several unequivocal conclusions. The results showed a copious and rising number of autophagic organelles that had specific localization. Interestingly the increase in autophagy that occurred just after fertilization has been proved to be crucial for correct initiation of the developmental programme: irreversible developmental delays and morphologic anomalies were induced by short autophagic inhibition. This work focused on the sea urchin model system and corroborates evidence on the need for self-digestion during development, enriching the knowledge on autophagy, a biological mechanism belonging to evolutionarily different organisms.

Amino-modified polystyrene nanoparticles affect signalling pathways of the sea urchin (Paracentrotus lividus) embryos

Polystyrene nanoparticles have been shown to pose serious risk to marine organisms including sea urchin embryos based on their surface properties and consequently behaviour in natural sea water. The aim of this study is to investigate the toxicity pathways of amino polystyrene nanoparticles (PS-NH₂, 50 nm) in Paracentrotus lividus embryos in terms of development and signalling at both protein and gene levels. Two sub-lethal concentrations of 3 and 4 μg/mL of PS-NH₂ were used to expose sea urchin embryos in natural sea water (PS-NH₂ as aggregates of 143 ± 5 nm). At 24 and 48 h post-fertilisation (hpf) embryonic development was monitored and variations in the levels of key proteins involved in stress response and development (Hsp70, Hsp60, MnSOD, Phospho-p38 Mapk) as well as the modulation of target genes (Pl-Hsp70, Pl-Hsp60, Pl-Cytochrome b, Pl-p38 Mapk, Pl-Caspase 8, Pl-Univin) were measured. At 48 hpf various striking teratogenic effects were observed such as the occurrence of cells/masses randomly distributed, severe skeletal defects and delayed development. At 24 hpf a significant up-regulation of Pl-Hsp70, Pl-p38 Mapk, Pl-Univin and Pl-Cas8 genes was found, while at 48 hpf only for Pl-Univin was observed. Protein profile showed different patterns as a significant increase of Hsp70 and Hsp60 only after 48 hpf compared to controls. Conversely, P-p38 Mapk protein significantly increased at 24 hpf and decreased at 48 hpf. Our findings highlight that PS-NH₂ are able to disrupt sea urchin embryos development by modulating protein and gene profile providing new understandings into the signalling pathways involved.

Chronic exposure to manganese sulfate leads to adverse dose-dependent effects on the neurobehavioral ability of rats

Manganese sulfate is the main combustion product of methylcyclopentadienyl manganese tricarbonyl (MMT). Currently, little is known about the neurobehavioral consequences of chronic manganese sulfate exposure. In this study, rats were treated with 0, 5.0, 10.0, and 20.0 mg/kg MnSO₄ ·H₂ O for 24 consecutive weeks via intraperitoneal injection. During the treatment period, spatial learning-memory ability was measured using the Morris water maze (MWM). At the end of the exposure period, spontaneous motor behavior and emotional status, hippocampal histologic changes, and Hsp70 mRNA levels were measured using the open-field test (OFT), hematoxylin-eosin staining and real-time quantitative PCR (RT-PCR), respectively. A dose-dependent decrease was noted in the spatial learning-memory ability and the spontaneous activities of rats (P < 0.05), and negative emotions differed significantly between the exposed groups and the control group (P < 0.05). Moreover, overt morphological changes in the hippocampuses of the exposed rats were detected. Cellular degeneration and death were also found. The Hsp70 mRNA levels of the hippocampal areas in the 20.0 mg/kg group (1.567 ± 0.236) were significantly increased compared with the control group (P < 0.05). These results suggest that chronic exposure to manganese sulfate can have adverse dose-dependent effects on rats' neurobehavioral ability, and the mechanism of abnormal hippocampal Hsp70 expression needs to be further explored. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1571-1579, 2016.

Diatom-derived oxylipins induce cell death in sea urchin embryos activating caspase-8 and caspase 3/7

Diatoms are an important class of unicellular algae that produce bioactive secondary metabolites with cytotoxic activity collectively termed oxylipins, including polyunsaturated aldehydes (PUAs), hydroxyacids (HEPEs), oxo-acids and epoxyalcohols. Previous results showed that at higher concentrations, the PUA decadienal induced apoptosis on copepods and sea urchin embryos via caspase-3 activation; at lower concentrations decadienal affected the expression levels of the caspase-8 gene in embryos of the sea urchin Paracentrotus lividus. In the present work, we studied the effects of other common oxylipins produced by diatoms: two PUAs (heptadienal and octadienal) and four hydroxyacids (5-, 9- 11- and 15-HEPE) on P. lividus cell death and caspase activities. Our results showed that (i) at higher concentrations PUAs and HEPEs induced apoptosis in sea urchin embryos, detected by microscopic observation and through the activation of caspase-3/7 and caspase-8 measured by luminescent assays; (ii) at low concentrations, PUAs and HEPEs affected the expression levels of caspase-8 and caspase-3/7 (isolated for the first time here in P. lividus) genes, detected by Real Time qPCR. These findings have interesting implications from the ecological point of view, given the importance of diatom blooms in nutrient-rich aquatic environments.

First Morphological and Molecular Evidence of the Negative Impact of Diatom-Derived Hydroxyacids on the Sea Urchin Paracentrotus lividus

Oxylipins (including polyunsaturated aldehydes [PUAs], hydoxyacids, and epoxyalcohols) are the end-products of a lipoxygenase/hydroperoxide lyase metabolic pathway in diatoms. To date, very little information is available on oxylipins other than PUAs, even though they represent the most common oxylipins produced by diatoms. Here, we report, for the first time, on the effects of 2 hydroxyacids, 5- and 15-HEPE, which have never been tested before, using the sea urchin Paracentrotus lividus as a model organism. We show that HEPEs do induce developmental malformations but at concentrations higher when compared with PUAs. Interestingly, HEPEs also induced a marked developmental delay in sea urchin embryos, which has not hitherto been reported for PUAs. Recovery experiments revealed that embryos do not recover following treatment with HEPEs. Finally, we report the expression levels of 35 genes (involved in stress, development, differentiation, skeletogenesis, and detoxification processes) to identify the molecular targets affected by HEPEs. We show that the 2 HEPEs have very few common molecular targets, specifically affecting different classes of genes and at different times of development. In particular, 15-HEPE switched on fewer genes than 5-HEPE, upregulating mainly stress-related genes at a later pluteus stage of development. 5-HEPE was stronger than 15-HEPE, targeting 24 genes, mainly at the earliest stages of embryo development (at the blastula and swimming blastula stages). These findings highlight the differences between HEPEs and PUAs and also have important ecological implications because many diatom species do not produce PUAs, but rather these other chemicals are derived from the oxidation of fatty acids.

Alterations in trace element levels and mRNA expression of Hsps and inflammatory cytokines in livers of duck exposed to molybdenum or/and cadmium

To evaluate the effects of dietary Molybdenum (Mo) or/and Cadmium (Cd) on trace elements and the mRNA expression levels of heat shock proteins (Hsps) and inflammatory cytokines in duck livers. 240 healthy 11-day-old ducks were randomly divided into six groups with 40 ducks in each group, which were treated with Mo or/and Cd at different doses on the basal diet for 120 days. On days 30, 60, 90 and 120, 10 birds in each group were randomly selected and euthanized and then the livers were collected to determine the contents of Mo, Cd, copper (Cu), iron (Fe), zine (Zn), Selenium (Se) and the mRNA expression levels of Hsps, inflammatory cytokines. In addition, liver tissues at 120 days were subjected to histopathological analysis with the optical microscope. The results showed that the mRNA expression of Hsp60, Hsp70, Hsp90, tumor necrosis factor-α (TNF-α), nuclear factor-kappa B (NF-κB), and cyclooxygenase-2 (COX-2) were significantly (P<0.01) upregulated in combination groups; Contents of Cu, Fe, Zn, and Se decreased in combined groups (P<0.05) in the later period of the test while contents of Mo and Cd significantly increased (P<0.01); Furthermore severe hepatocyte diffuse fatty, hepatic cords swelling, hepatic sinusoid disappeared, and inflammatory cells infiltrated around the hepatic central vein were observed in Mo combined with Cd groups. The results indicated that dietary Mo or/and Cd might lead to stress, inflammatory response, tissue damage and disturb homeostasis of trace elements in duck livers. Moreover the two elements showed a possible synergistic relationship. And the high mRNA expression of HSPs and inflammatory cytokines may play a role in the resistance of liver toxicity induced by Mo and Cd.

Autophagy as a defense strategy against stress: focus on Paracentrotus lividus sea urchin embryos exposed to cadmium

Autophagy is used by organisms as a defense strategy to face environmental stress. This mechanism has been described as one of the most important intracellular pathways responsible for the degradation and recycling of proteins and organelles. It can act as a cell survival mechanism if the cellular damage is not too extensive or as a cell death mechanism if the damage/stress is irreversible; in the latter case, it can operate as an independent pathway or together with the apoptotic one. In this review, we discuss the autophagic process activated in several aquatic organisms exposed to different types of environmental stressors, focusing on the sea urchin embryo, a suitable system recently included into the guidelines for the use and interpretation of assays to monitor autophagy. After cadmium (Cd) exposure, a heavy metal recognized as an environmental toxicant, the sea urchin embryo is able to adopt different defense mechanisms, in a hierarchical way. Among these, autophagy is one of the main responses activated to preserve the developmental program. Finally, we discuss the interplay between autophagy and apoptosis in the sea urchin embryo, a temporal and functional choice that depends on the intensity of stress conditions.

Effect of silver nanoparticles on Mediterranean sea urchin embryonal development is species specific and depends on moment of first exposure

With the ever growing use of nanoparticles in a broad range of industrial and consumer applications there is increasing likelihood that such nanoparticles will enter the aquatic environment and be transported through freshwater systems, eventually reaching estuarine or marine waters. Due to silver's known antimicrobial properties and widespread use of silver nanoparticles (AgNP), their environmental fate and impact is therefore of particular concern. In this context we have investigated the species-specific effects of low concentrations of 60 nm AgNP on embryonal development in Mediterranean sea urchins Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis. The sensitivity of urchin embryos was tested by exposing embryos to nanoparticle concentrations in the 1-100 μg L(-1) range, with times of exposure varying from 30 min to 24 h (1 h-48 h for S. granularis) post-fertilisation which corresponded with fertilized egg, 4 cell, blastula and gastrula development phases. The most sensitive species to AgNP was A. lixula with significant modulation of embryonal development at the lowest AgNP concentrations of 1-10 μg L(-1) with high numbers of malformed embryos or arrested development. The greatest impact on development was noted for those embryos first exposed to nanoparticles at 6 and 24 h post fertilisation. For P. lividus, similar effects were noted at higher concentrations of 50 μg L(-1) and 100 μg L(-1) for all times of first exposure. The S. granularis embryos indicated a moderate AgNP impact, and significant developmental abnormalities were recorded in the concentration range of 10-50 μg L(-1). As later post-fertilisation exposure times to AgNP caused greater developmental changes in spite of a shorter total exposure time led us to postulate on additional mechanisms of AgNP toxicity. The results herein indicate that toxic effects of AgNP are species-specific. The moment at which embryos first encounter AgNP is also shown to be an important factor in the development of abnormalities, and future applications of the sea urchin embryo development test for nanoparticle toxicity testing should carefully address the specific phase of development of embryos when nanoparticles are first introduced.

Maternal Exposure to Cadmium and Manganese Impairs Reproduction and Progeny Fitness in the Sea Urchin Paracentrotus lividus

Metal contamination represents one of the major sources of pollution in marine environments. In this study we investigated the short-term effects of ecologically relevant cadmium and manganese concentrations (10(-6) and 3.6 x 10(-5) M, respectively) on females of the sea urchin Paracentrotus lividus and their progeny, reared in the absence or presence of the metal. Cadmium is a well-known heavy metal, whereas manganese represents a potential emerging contaminant, resulting from an increased production of manganese-containing compounds. The effects of these agents were examined on both P. lividus adults and their offspring following reproductive state, morphology of embryos, nitric oxide (NO) production and differential gene expression. Here, we demonstrated that both metals differentially impaired the fertilization processes of the treated female sea urchins, causing modifications in the reproductive state and also affecting NO production in the ovaries. A detailed analysis of the progeny showed a high percentage of abnormal embryos, associated to an increase in the endogenous NO levels and variations in the transcriptional expression of several genes involved in stress response, skeletogenesis, detoxification, multi drug efflux processes and NO production. Moreover, we found significant differences in the progeny from females exposed to metals and reared in metal-containing sea water compared to embryos reared in non-contaminated sea water. Overall, these results greatly expanded previous studies on the toxic effects of metals on P. lividus and provided new insights into the molecular events induced in the progeny of sea urchins exposed to metals.

Cellular responses and HSP70 expression during wound healing in Holothuria tubulosa (Gmelin, 1788)

Wound repair is a key event in the regeneration mechanisms of echinoderms. We studied, at the behavioural, cellular and molecular levels, the wound healing processes in Holothuria tubulosa after injuries to the body wall. The experiments were performed for periods of up to 72 h, and various coelomocyte counts, as well as the expression of heat shock proteins (HS27, HSP70 and HSP90), were recorded. Dermal wound healing was nearly complete within 72 h. In the early stages, we observed the injured animals twisting their bodies to keep their injuries on the surface of the water for the extrusion of the buccal pedicles. At the cellular level, we found time-dependent variations in the circulating coelomocyte counts. After injury, in particular, we observed a significant increase in spherule cells at 2.5 h post-injury. Using the western blot method, we observed and reported that the wounds produced, compared with controls, a significant increase in HSP27 and HSP70 expression in coelomocytes, whereas HSP70 was increased in scar tissue and HSP90 was increased only in cell-free coelomic fluid. These results highlight that the wounds were responsible for the stress condition with the induction of cellular and biochemical responses.

Transcriptional and biochemical effects of cadmium and manganese on the defense system of Octopus vulgaris paralarvae

Due to anthropogenic activities the relative concentrations of cadmium and manganese have increased in the marine environment. Cephalopods are able to accumulate such metals and, as inhabitant of coastal waters, Octopus vulgaris is continuously exposed to anthropogenic activities. Since no study is available on the effects of heavy metals at molecular level in developing octopuses, herein we exposed 1-day-old paralarvae for 24 h to 10, 100, and 1000 μg/L of CdCl2 or MnCl2. Cd exerted a concentration-dependent inhibition of survival and a reduction in growth rate was shown while Mn exposure did not affect the survival rate even at the highest concentrations. Gene expression profiles of hsp70, sod, cat, and gst genes were analyzed by quantitative real-time PCR and defined patterns of transcription were observed. Moreover posttranscriptional analyses were also performed suggesting the impairment of metabolic functions, under strong oxidative conditions (as occurred in paralarvae exposed to Cd) or the complete detoxification events (as occurred in paralarvae exposed to Mn).

Stress response to cadmium and manganese in Paracentrotus lividus developing embryos is mediated by nitric oxide

Increasing concentrations of contaminants, often resulting from anthropogenic activities, have been reported to occur in the marine environment and affect marine organisms. Among these, the metal ions cadmium and manganese have been shown to induce developmental delay and abnormalities, mainly reflecting skeleton elongation perturbation, in the sea urchin Paracentrotus lividus, an established model for toxicological studies. Here, we provide evidence that the physiological messenger nitric oxide (NO), formed by l-arginine oxidation by NO synthase (NOS), mediates the stress response induced by cadmium and manganese in sea urchins. When NO levels were lowered by inhibiting NOS, the proportion of abnormal plutei increased. Quantitative expression of a panel of 19 genes involved in stress response, skeletogenesis, detoxification and multidrug efflux processes was followed at different developmental stages and under different conditions: metals alone, metals in the presence of NOS inhibitor, NO donor and NOS inhibitor alone. These data allowed the identification of different classes of genes whose metal-induced transcriptional expression was directly or indirectly mediated by NO. These results open new perspectives on the role of NO as a sensor of different stress agents in sea urchin developing embryos.

Molecular response to toxic diatom-derived aldehydes in the sea urchin Paracentrotus lividus

Diatoms are dominant photosynthetic organisms in the world’s oceans and represent a major food source for zooplankton and benthic filter-feeders. However, their beneficial role in sustaining marine food webs has been challenged after the discovery that they produce secondary metabolites, such as polyunsaturated aldehydes (PUAs), which negatively affect the reproductive success of many invertebrates. Here, we report the effects of two common diatom PUAs, heptadienal and octadienal, which have never been tested before at the molecular level, using the sea urchin, Paracentrotus lividus, as a model organism. We show that both PUAs are able to induce teratogenesis (i.e., malformations), as already reported for decadienal, the better-studied PUA of this group. Moreover, post-recovery experiments show that embryos can recover after treatment with all three PUAs, indicating that negative effects depend both on PUA concentrations and the exposure time of the embryos to these metabolites. We also identify the time range during which PUAs exert the greatest effect on sea urchin embryogenesis. Finally, we report the expression levels of thirty one genes (having a key role in a broad range of functional responses, such as stress, development, differentiation, skeletogenesis and detoxification processes) in order to identify the common targets affected by PUAs and their correlation with morphological abnormalities. This study opens new perspectives for understanding how marine organisms afford protection from environmental toxicants through an integrated network of genes.

Sea urchin embryos exposed to cadmium as an experimental model for studying the relationship between autophagy and apoptosis

The sea urchin embryo is a suitable model that offers an excellent opportunity to investigate different defence strategies activated in stress conditions. We previously showed that cadmium accumulates in a dose- and time-dependent manner into embryonic cells, activating different stress and defence mechanisms, including the synthesis of HSPs and the onset of apoptosis and/or autophagy. In this paper we investigated the functional relationship between autophagy and apoptosis, evaluating apoptosis signals in cadmium-exposed Paracentrotus lividus embryos with inhibited autophagy. We found that the inhibition of autophagy produced the concurrent reduction of apoptosis, suggesting that the two phenomena are functionally related. Considering the catabolic role of autophagy, an energetic hypothesis to explain the relationship was evaluated. Using a substrate for ATP production, we found that apoptosis, assessed by TUNEL and cleaved caspase-3 immunocytochemistry, was substantially restored in cadmium-treated embryos where autophagy was inhibited by 3-Methyladenine. On the basis of these results, we propose that, autophagy could play a crucial role in stress response of this organism because autophagy could energetically contribute to apoptotic execution through its catabolic role.

The effect of manganese-induced cytotoxicity on mRNA expressions of HSP27, HSP40, HSP60, HSP70 and HSP90 in chicken spleen lymphocytes in vitro

The purpose of this study was to investigate the effect of manganese (Mn)-induced cytotoxicity on heat shock proteins in chicken spleen lymphocytes. Lymphocytes were cultured in medium in the absence and presence of MnCl2 (2 × 10(-4), 4 × 10(-4), 6 × 10(-4), 8 × 10(-4), 10 × 10(-4), and 12 × 10(-4) mmol/L) for 12, 24, 36, and 48 h in vitro. Then, the mRNA levels of HSP27, HSP40, HSP60, HSP70, and HSP90 were examined by real-time quantitative PCR. The results showed that the mRNA levels of HSP27, HSP40, HSP60, HSP70, and HSP90 in all treatment groups at all time points, except mRNA levels of HSP27 at 48 h, had the same tendency. As manganese concentration increased, the mRNA expression of the heat shock proteins first increased and then decreased. In other words, we demonstrated that the mRNA expression of the heat shock proteins was induced at lower concentrations of manganese and was inhibited at higher concentrations. Mn had a dosage-dependent effect on HSP27, HSP40, HSP60, HSP70, and HSP90 mRNA expression in chicken spleen lymphocytes in vitro.

Cadmium induced hepatotoxicity in chickens (Gallus domesticus) and ameliorative effect by selenium

Cadmium (Cd) is one of the most toxic metal compounds released into the environment. It was well known that Cd induced hepatotoxicity in animal models. However, little is known about the negative effects of Cd toxicity in the liver of birds. To investigate the Cd hepatotoxicity in birds and the protective effects of selenium (Se) against subchronic exposure to dietary Cd, 100-day-old cocks received either Se (as 10mg Na2SeO3 per kg of diet), Cd (as 150mg CdCl2 per kg of diet) or Cd+Se in their diets for 60 days. Histological and ultrastructural changes in the liver, the concentrations of Cd and Se, the lipid peroxidation (LPO) and nitric oxide (NO) production, the activities of the antioxidants superoxide dismutase (SOD) and glutathione peroxidase (GPx), nitric oxide synthase (NOS) activities and apoptosis were determined. Exposure to Cd significantly reduced SOD and GPx activity, Se content in the liver tissue. It increased the LPO and NO production, the numbers of apoptotic cells and Cd concentration and caused obvious histopathological changes in the liver. Concurrent treatment with Se reduced the Cd-induced liver histopathological changes, oxidative stress, overexpression of NO and apoptosis, suggesting that the toxic effects of Cd on the liver is partly ameliorated by inorganic Se. Se supplementation also modified the distribution of Cd in the liver.

Coupling of random amplified polymorphic DNA profiles analysis and high resolution capillary electrophoresis system for the assessment of chemical genotoxicity

Cadmium (Cd) can be toxic to terrestrial snails, but few data are available about its genotoxic effects on early life stages (ELS). The aim of this study was to investigate the genotoxic potential of Cd in embryos of Helix aspersa using a new approach that couples Random Amplified Polymorphic DNA (RAPD) and a high-resolution capillary electrophoresis system (HRS). Clutches of H. aspersa were exposed to Cd solutions (2, 4, and 6 mg/L) from the beginning of their embryonic development. In addition to a dose-dependent effect of Cd on hatching rate, DNA fragmentation was observed in embryos that were exposed to 6 mg Cd/L. The analysis of RAPD products with HRS showed differences between the profiles of exposed and nonexposed embryos, starting at 2 mg Cd/L. In comparison to the profiles of the control samples, all profiles from the exposed snails exhibited an additional 270 bp DNA fragment and lacked a 450 bp DNA fragment. These profile modifications are related to the genotoxic effect of Cd on the ELS of H. aspersa . Our study demonstrates the efficacy of coupling RAPD and HRS for a rapid and efficient screening of the effects of chemicals on DNA.

The response profiles of HSPA12A and TCTP from Mytilus galloprovincialis to pathogen and cadmium challenge

Heat shock 70 kDa protein 12A (HSPA12A) is an atypical member of HSP70 family, and the translationally controlled tumor protein (TCTP) is a novel HSP with chaperone-like activity. They are both involved in protecting organisms against various stressors. In the present study, the cDNAs of HSPA12A and TCTP (called MgHSPA12A and MgTCTP) were identified from Mytilus galloprovincialis by RACE approaches. The full-length cDNA of MgHSPA12A and MgTCTP encoded a peptide of 491 and 171 amino acids, respectively. Real-time PCR was employed to analyze the tissue distribution and temporal expression of these two genes after bacterial challenge and cadmium (Cd) exposure. It was found that the transcripts of MgHSPA12A and MgTCTP were dominantly expressed in gonad and muscle, respectively. The expression level of MgTCTP at 48 h post Vibrio anguillarum challenge was detected to be significantly up-regulated in hepatopancreas (P < 0.05). As concerned to Cd exposure, 2.0-fold increase of MgHSPA12A expression compared to that of the control was observed at 48 h in 5 μg/L Cd(2+)-treated group, while the expression levels of MgTCTP were significantly decreased after exposed to both 5 and 50 μg/L Cd(2+) for 24 h and 96 h. These results suggested the potential involvement of MgHSPA12A and MgTCTP in the mediation of the immune responses and environmental stress in mussels.