DNA damage in marine rock oyster (Saccostrea Cucullata) exposed to environmentally available PAHs and heavy metals along the Arabian Sea coast

Study on reproductive endocrine disturbance and DNA damage mechanism of female Ruditapes philippinarum under Benzo[a]pyrene stress

The reproductive toxicity of polycyclic aromatic hydrocarbons (PAHs) in aquatic organisms has attracted increasing attention from scholars. Currently, research in this field primarily focuses on vertebrates such as zebrafish and other model species. However, there is still a significant knowledge gap in the toxicity of PAHs to invertebrates and its potential mechanisms. Benzo[a]pyrene (B[a]P) is one of the most representative PAHs. In this study, female Ruditapes philippinarum (R. philippinarum) was treated with B[a]P concentrations of 0, 0.8, 4, and 20 μg/L to investigate reproductive indicators in the proliferative, growth, mature, and spawn stages. Transcriptomics was used to investigate the expression of genes associated with the reproductive endocrine system, DNA repair, autophagy, apoptosis, and ovarian development at different reproductive stages. Our results suggested that B[a]P disrupted the endocrine system by interfering with the production of steroid hormones and the transmission of estrogen signals in female R. philippinarum. The structure of the ovarian DNA duplex is severely damaged under the stress of B[a]P, and a series of cellular responses caused by DNA damage are also interfered. Additionally, we observed a reduction in the gonadosomatic index (GSI) and mature oocytes numbers after B[a]P exposed. Tissue section indicated that severe damage to the ovarian structure at mature and spawn stages. In conclusion, this study combined transcriptomic and toxicological to explore the negative effects on ovarian development induced by B[a]P, focusing on reproductive endocrine disturbance and DNA damage.

Effect of elevated temperature, sea water acidification, and phenanthrene on the expression of genes involved in the shell and pearl formation of economic pearl oyster (Pinctada radiata)

Our study aims to examine the effect of some stressors on the gene expression levels of shell matrix proteins in a pearl oyster. Oysters were exposed to the different combinations of the temperature, pH, and phenanthrene concentration is currently measured in the Persian Gulf and the predicted ocean warming and acidification for 28 days. The expression of all the studied genes was significantly downregulated. Time and temperature had the greatest effects on the decreases in n19 and n16 genes expression, respectively. Aspein and msi60 genes expression were highly influenced by pH. Pearlin was affected by double interaction temperature and phenanthrene. Moreover, a correlation was observed among the expression levels of studied genes. This study represents basic data on the relationship between mRNA transcription genes involved in the shell and pearl formation and climate changes in pollutant presence conditions and acclimatizing mechanism of the oyster to the future scenario as well.

Risk assessment of polycyclic aromatic hydrocarbon infested sediments along the coast of Goa, India

Goa, a small state in India, is a tourist hotspot known for its coastline and beaches. Anthropogenic activities lead to pollution in the environment. Amongst many other pollutants, polycyclic aromatic hydrocarbons represent a major class of contaminants owing to their widespread distribution and protracted environmental persistence. No information is available about the levels of Polycyclic aromatic hydrocarbon (PAH) contamination in the sediments along the coastline of Goa. The study aimed to establish a baseline for PAH concentrations in the sediments along the shoreline to help comment on the pollution levels caused and thereby understand the risk and their impact on the marine life therein. The total concentration of PAHs along the selected sampling sites of the Goa coastline was 1.00 to 875 μg g-1. Maximum PAH concentrations were detected in the Divar island mangrove (875 μg g-1); the least was observed at Galgibaga beach (365 μg g-1). The results revealed that the sediment of the Goa coastline is heavily contaminated with PAH. Source apportionment of PAHs was analysed based on diagnostic ratios, and results exhibited that petroleum products and their combustion were primarily responsible for their generation. The results of risk quotients showed that the values are way above effect range median (ER-M), indicating these could pose a high risk to the ecosystem.

Environmental behaviors of emerging contaminants in freshwater ecosystem dominated by submerged plants: A review

Persistent exposure of emerging contaminants (ECs) in freshwater ecosystem has initiated intense global concerns. Freshwater ecosystem dominated by submerged plants (SP-FES) has been widely constructed to control eutrophic water. However, the environmental behaviors (e.g. migration, transformation, and degradation) of ECs in SP-FES have rarely been concerned and summarized. This review briefly introduced the sources of ECs, the pathways of ECs entering into SP-FES, and the constituent elements of SP-FES. And then the environmental behaviors of dissolved ECs and refractory solid ECs in SP-FES were comprehensively summarized, and the feasibility of removing ECs from SP-FES was critically evaluated. Finally, the challenges and perspectives on the future development for ECs removal from SP-FES were prospected, giving possible research gaps and key directions. This review will provide theoretical and technical support for the effective removal of ECs in freshwater ecosystem, especially in SP-FES.

A review on simultaneous heavy metal removal and organo-contaminants degradation by potential microbes: Current findings and future outlook

Industrial processes result in the production of heavy metals, dyes, pesticides, polyaromatic hydrocarbons (PAHs), pharmaceuticals, micropollutants, and PFAS (per- and polyfluorinated substances). Heavy metals are currently a significant problem in drinking water and other natural water bodies, including soil, which has an adverse impact on the environment as a whole. The heavy metal is highly poisonous, carcinogenic, mutagenic, and teratogenic to humans as well as other animals. Multiple polluted sites, including terrestrial and aquatic ecosystems, have been observed to co-occur with heavy metals and organo-pollutants. Pesticides and heavy metals can be degraded and removed concurrently from various metals and pesticide-contaminated matrixes due to microbial processes that include a variety of bacteria, both aerobic and anaerobic, as well as fungi. Numerous studies have examined the removal of heavy metals and organic-pollutants from different types of systems, but none of them have addressed the removal of these co-occurring heavy metals and organic pollutants and the use of microbes to do so. Therefore, the main focus of this review is on the recent developments in the concurrent microbial degradation of organo-pollutants and heavy metal removal. The limitations related to the simultaneous removal and degradation of heavy metals and organo-pollutant pollutants have also been taken into account.

Changes in metabolic profiles of amphipods Allorchestes compressa after acute exposures to copper, pyrene, and their mixtures

Amphipods are ideal indicators for biomonitoring and ecotoxicological studies of environmental contaminants because they are extensively distributed in aquatic environments, are easy to collect and are important in nutrient cycling. Marine amphipods (Allorchestes compressa) were exposed to two concentrations of copper and pyrene, and their mixtures, for 24 and 48 h. Changes in polar metabolites were assessed using Gas Chromatography Mass Spectrometry (GC-MS)-based untargeted metabolomics. Generally, limited metabolite changes were observed for copper and pyrene single exposures (eight and two significant metabolites, respectively), while 28 metabolites had changed following exposures to mixtures. Furthermore, changes were mainly observed after 24 h but had seemingly returned to control levels after 48 h. Multiple types of metabolites were affected including amino acids, Tricarboxylic acid (TCA) cycle intermediates, sugars, fatty acids, and hormones. This study highlights the sensitivity of metabolomics in assessing the impacts of low concentrations of chemicals compared to traditional ecotoxicological endpoints.

Effects of wildfire ashes on aquatic invertebrates: First molecular approach on Chironomus riparius larvae

The wildfire magnification in recent years has raised increasing concern about their adverse impacts on the environment. Wildfires are recognized as an important source of diffuse pollution for the nearby aquatic systems being potentially toxic to aquatic life. Albeit previous studies with wildfire runoff/ashes observed effects in aquatic organisms, to date, different severity origins of ashes and their impact at the sub-organismal level on aquatic biota have not been assessed. In this work, the molecular response of Chironomus riparius exposed to wildfire with low (LS) and high (HS) severity ashes from burnt Pine plantations was evaluated by employing an array of 42 genes related to crucial metabolic pathways by Real time-PCR. IV instar larvae were exposed for 72 h to aqueous extract of ashes (12.5 %, 25 %, 50 %, 75 % and 100 %) prepared from LS and HS ashes. Mn, Zn, and Pb were the metals found at highest concentration in both ash extracts, for HS notable Cd, Mn and Cr presence. From the 42 genes studied only 4 were not altered (22 genes modulated their response by LS and 38 genes in the case of HS) showing the opposite response at 100% with downregulated by LS and upregulated by HS. The 12.5 %, 25 %, 100 % HS and 25 % LS were the main modulators, confirmed by the integrative biomarkers response (IBR). Remarkable genotoxicity was generated by ashes even activating the apoptosis response, and endocrine disruption observed could modify the development. Moreover, detoxification and stress response were strongly activated, limiting the organism's future response to external aggressions. The employment of this novelty approach with molecular tools act as early alarm signal preventing greater damages. Overall, wildfire ashes showed to be a significant environmental disruptor to C. riparius even at lower concentration and the short exposure time employed, emphasizing the strong impact of wildfires on aquatic systems.

Identification of a Green Algal Strain Collected from the Sarno River Mouth (Gulf of Naples, Italy) and Its Exploitation for Heavy Metal Remediation

Heavy metals (HMs) can induce both chronic and acute harmful effects on marine and freshwater biota. The environmental impact of HMs in freshwater, seawater, soil, and wastewater can be limited using microbes, including microalgae, that are able to remove metals from environmental matrices. Indeed, they can passively adsorb and actively accumulate these persistent pollutants within their organelles, limiting their detrimental effects on cellular metabolism. The Sarno River is a 30 km long freshwater stream located in Southern Italy, polluted by partially untreated municipal, agricultural, and industrial wastewaters. In spite of this, microalgal cultures from Sarno River or Sarno River Mouth have never been established. In the present study, we isolated a green algal strain from the Sarno River Mouth and determined its ability to grow in polluted seawater containing different concentrations of cadmium, lead, or zinc. This strain was found to be able to accumulate these elements within its biomass in a dose-dependent manner. Growth inhibition experiments confirm the relatively low toxicity of Cd and Pb below 50 µM, while algal growth was seriously affected in Zn-amended media. To the best of our knowledge, this is the first study focused on the ability of microalgae from Sarno River Mouth to tolerate and uptake HMs.

Bioaccumulation of polycyclic aromatic hydrocarbons (PAH) in Polychaeta Marphysa sanguinea in the anthropogenically impacted Tunis Lagoon: DNA damage and immune biomarkers

This work assessed the impact of polycyclic aromatic hydrocarbons (PAHs) on the polychaeta Marphysa sanguinea in Tunis Lagoon. Highest PAHs concentrations were accumulated at station E with maximum Σ PAH of 6028,87 ng/g DW. Changes in animal physiology were clearly related to bioaccumulated PAH. In fact, high levels of immune biomarkers (cyclooxygenase [COX] and lysozyme activity with maximum of 44631,10 FU/mn/mg protein and 0,017 lysozyme activity/mn/mg protein, respectively) were recorded at stations B and E. Triacylglycerol (TAG), the energy source, was lowest at the most polluted stations (E and B), while phospholipids (PL) were highest at the control station. Statistical analysis revealed a probable effect of both low and high molecular weight PAHs on variations in energy storage lipids (TAG and sterol and wax esters [SE/WE]) and membrane lipids, particularly PL. Our results encourage the use of M. sanguinea to assess pollution levels in coastal ecosystems.

Implications for the seafood industry, consumers and the environment arising from contamination of shellfish with pharmaceuticals, plastics and potentially toxic elements: A case study from Irish waters with a global orientation

Shellfish are a rich source of minerals, B-vitamins and omega-3 to the human diet. The global population is expected to reach 9.6 billion people by 2050 where there will be increased demand for shellfish and for sustained improvements in harvesting. The production of most consumed species of shellfish is sea-based and are thus susceptible to in situ environmental conditions and water quality. Population growth has contributed to expansion of urbanization and the generation of effluent and waste that reaches aquatic environments, potentially contaminating seafood by exposure to non-treated effluents or inappropriately discarded waste. Environmental contaminants as microplastics (MP), pharmaceuticals (PHAR) and potentially toxic contaminants (PTE) are being identified in all trophic levels and are a current threat to both shellfish and consumer safety. Immunotoxicity, genotoxicity, fertility reduction, mortality and bioaccumulation of PTE are representative examples of the variety of effects already established in contaminated shellfish. In humans, the consumption of contaminated shellfish can lead to neurological and developmental effects, reproductive and gastrointestinal disorders and in extreme cases, death. This timely review provides insights into the presence of MP, PHAR and PTE in shellfish, and estimate the daily intake and hazard quotient for consumption behaviours. Alternatives approaches for seafood depuration that encompass risk reduction are addressed, to reflect state of the art knowledge from a Republic of Ireland perspective. Review of best-published literature revealed that MP, PHAR and PTE contaminants were detected in commercialised species of shellfish, such as Crassostrea and Mytilus. The ability to accumulate these contaminants by shellfish due to feeding characteristics is attested by extensive in vitro studies. However, there is lack of knowledge surrounding the distribution of these contaminants in the aquatic environment their interactions with humans. Preventive approaches including risk assessment are necessary to safeguard the shellfish industry and the consumer.

Bioaccumulation, Detoxification, and Biological Macromolecular Damage of Benzo[a]pyrene in Exposure in Tissues and Subcellular Fractions of Scallop Chlamys farreri

Because of the persistence and high toxicity of benzo[a]pyrene (B[a]P), the bioaccumulation and detoxification mechanisms of B[a]P have been studied extensively at the tissue level; but the data at the subcellular level in bivalves have not been reported. The present study was conducted to investigate the effects of B[a]P exposure on bioaccumulation, detoxification, and biomacromolecular damage in gills, digestive glands, and their subcellular fractions of the scallop Chlamys farreri. The subcellular fraction contains cytoplasm, mitochondria, microsome, nucleus, cell membrane, and overall organelle. The results demonstrated that B[a]P accumulation showed a clear time-dose effect. Based on the time-dependent accumulation of B[a]P in subcellular fractions, we speculated that the intracellular migration order of B[a]P was cell membrane, organelle, and nucleus in turn. Considering the difference of B[a]P accumulation may be related to B[a]P metabolism, we have further confirmed that the activities of B[a]P metabolizing enzymes in scallop tissues and subcellular fractions were significantly tempted by B[a]P (p < 0.05), including 7-ethoxyresorufin O-deethylase (increased), glutathione-S-transferase (GST; decreased), and superoxide dismutase (increased). First, GST was detected in bivalve cytoplasm and microsome. Second, B[a]P exposure also caused biomacromolecules damage. The results demonstrated that mitochondria and microsome were more vulnerable to lipid peroxidation than cell membrane and nucleus. Taken together, the present study fills some of the gaps in our knowledge of the bioaccumulation and detoxification mechanisms of C. farreri exposed to B[a]P in subcellular fractions and deeply explores the transportation and the main metabolic and damage sites of polycyclic aromatic hydrocarbons (PAHs) in cells, which helped us to comprehensively understand the toxic mechanism of PAHs on bivalves. Environ Toxicol Chem 2022;41:2353-2364. © 2022 SETAC.

Hibiscus sabdariffa Extract Protects HaCaT Cells against Phenanthrene-Induced Toxicity through the Regulation of Constitutive Androstane Receptor/Pregnane X Receptor Pathway

Phenanthrene (Phe) exposure is associated with skin ageing, cardiotoxicity and developmental defects. Here, we investigated the mode of Phe toxicity in human keratinocytes (HaCaT cells) and the attenuation of toxicity on pre-treatment (6 h) with ethanol extract of Hibiscus sabdariffa calyxes (HS). Cell viability, reactive oxygen species (ROS) generation, mitochondrial membrane potential (ΔΨm) alteration, changes in the transcriptional activity of selected genes involved in phase I and II metabolism, antioxidant response and gluconeogenesis, western blot and docking studies were performed to determine the protective effect of HS against Phe. Phe (250 μM) induced cytotoxicity in HaCaT cells through AhR-independent, CAR/PXR/RXR-mediated activation of CYP1A1 and the subsequent alterations in phase I and II metabolism genes. Further, CYP1A1 activation by Phe induced ROS generation, reduced ΔΨm and modulated antioxidant response, phase II metabolism and gluconeogenesis-related gene expression. However, pre-treatment with HS extract restored the pathological changes observed upon Phe exposure through CYP1A1 inhibition. Docking studies showed the site-specific activation of PXR and CAR by Phe and inhibition of CYP1A1 and CYP3A4 by the bioactive compounds of HS similar to that of the positive controls tested. Our results conclude that HS extract can attenuate Phe-induced toxicity in HaCaT cells through CAR/PXR/RXR mediated inhibition of CYP1A1.

Trace element bioaccumulation in edible red seaweeds (Rhodophyta): A risk assessment for consumers

As a precursor to risk assessment and risk management through consuming contaminated seafood, food safety needs to be quantified and assured. Seaweed is an increasing dietary component, especially in developing countries, but there are few studies assessing uptake rates of contaminants from this route. As such, the present study determined likely human uptake due to the trace elemental (Fe, Mn, Ni, Cu, Zn, Se, Hg, and As) concentrations in the edible red seaweeds (Rhodophyta) Gelidium pusillum and Hypnea musciformis, growing in the industrialised Cox's Bazar coastal area of Bangladesh. Metal and metalloid concentrations in G. pusillum were in the order (mg/kg): Fe (797 ± 67) > Mn (69 ± 4) > Ni (12 ± 5) > Zn (9 ± 4) > Cu (9 ± 4) >Se (0.1 ± 0.1) > Hg (0.1 ± 0.01), and in H. musciformis: Fe (668 ± 58) > Mn (28 ± 5) > Ni (14 ± 2) > Zn (11 ± 5) > Cu (6 ± 4) >Se (0.2 ± 0.03) > Hg (0.04 ± 0.01). Despite the industrial activities in the area, and based on 10 g. day^-1 seaweed consumption, it is concluded that these concentrations pose no risk to human health as part of a normal diet according to the targeted hazard quotient and hazard index (THQ and HI) (values < 1). In addition, and as a novel aspect for seaweeds, Selenium Health Benefit Values (Se-HBV) were determined and found to have positive values. Seaweed can be used as an absorber of inorganic metals for removing contamination in coastal waters. The results are a precursor to further research regarding the efficiency and rate at which seaweeds can sequester metal contamination in water. In addition, management techniques need to be developed thereby to control the contaminant inputs.

Reproductive toxicity induced by benzo[a]pyrene exposure: first exploration highlighting the multi-stage molecular mechanism in female scallop Chlamys farreri

Reproductive toxicity induced by benzo[a]pyrene (B[a]P) exposure has received great ecotoxicological concerns. However, huge gaps on the molecular mechanism still exist in bivalves. In this study, reproduction-related indicators were investigated in female scallops Chlamys farreri during life cycle of proliferative, growth, mature, and spawn stages, under gradient concentrations of B[a]P at 0, 0.04, 0.4, and 4 μg/L. Meanwhile, a multi-stage ovarian transcriptome analysis under 4 μg/L B[a]P exposure was also conducted to elucidate the potential molecular mechanisms. The results indicated that life-cycle exposure to 0.4 and 4 μg/L B[a]P significantly decreased GSI and sex steroid levels. Even 0.04 μg/L B[a]P could play the adverse role in DNA integrity at the mature and spawn stages. Ovarian histological sections showed that B[a]P inhibited the maturation and release of oocytes. Through the functional enrichment analysis of differentially expressed genes (DEGs) from transcriptome data, 18 genes involved in endocrine disruption effects, DNA damage and repair, and oogenesis were selected and further determined by qRT-PCR. The downregulation of genes involved in steroidogenic and estrogen signaling pathways indicated that B[a]P could cause endocrine disruption through both receptor-dependent and receptor-independent pathways. The variations of gene expressions involved in DNA single-strand break and repair implied the presence of toxic mechanisms similar with vertebrates. Additionally, the changes of gene expressions of cell cycle, apoptosis, and cell adhesion suggested that exposure to B[a]P possibly caused the reproductive toxicity effects by affecting oogenesis. Taken together, this study was a pioneer in combining genome-wide transcriptomic analysis with its corresponding reproductive indicators (GSI, sex steroid levels, DNA single-strand break, and histological sections) to explore the bivalves' toxic mechanisms under B[a]P exposure. Meanwhile, some genes involved in estrogen signaling pathway and DNA damage were firstly analyzed in bivalves, and the expression data might be useful in establishing new hypotheses and discovering new biomarkers for marine biomonitoring.

Immunotoxicity pathway and mechanism of benzo[a]pyrene on hemocytes of Chlamys farreri in vitro

Benzo[a]pyrene (B[a]P), a typical PAHs widely existing in the marine environment, has been extensively studied for its immunotoxicity due to its persistence and high toxicity. Nevertheless, the immunotoxicity mechanism remain incompletely understood. In this study, isolated hemocytes of Chlamys farreri were exposed at three concentrations of B[a]P (5, 10 and 15 μg/mL), and the effects of B[a]P on detoxification metabolism, signal transduction, humoral immune factors, exocytosis and phagocytosis relevant proteins and immune function at 0, 6, 12, 24 h were studied. Results illustrated the AhR, ARNT and CYP1A1 were significantly induced by B[a]P at 12 h. Additionally, the content of B[a]P metabolite BPDE increased in a dose-dependent manner with pollutants. Under B[a]P stimulation, the expressions of PTK (Src, Fyn) and PLC-Ca²⁺-PKC pathway gene increased significantly, while the transcription level of AC-cAMP-PKA pathway gene decreased remarkably. Additionally, the expressions of nuclear transcription factors (CREB, NF-κB), complement system genes and C-type lectin genes up-regulated obviously. The gene expressions of phagocytosis and exocytosis related proteins were also notably affected. 5 μg/mL B[a]P could promote phagocytosis in a transitory time, but with the increase of exposure time and concentration of B[a]P, the phagocytosis, antibacterial and bacteriolytic activities gradually decreased. These results indicated that similar to vertebrates, BPDE, the metabolite of B[a]P, mediated downstream signal transduction via PTK in bivalves. The declined of the immune defense ability of hemocytes might be closely related to the inhibition of AC-cAMP-PKA pathway and the imbalance of intracellular Ca²⁺ pathway. In addition, the results manifested that complement and lectin systems play a significant role in regulating immune response. In this study, the direct relationship between detoxification metabolism and immune signal transduction in bivalves under B[a]P stress was demonstrated for the first time, which provided important information for the potential molecular mechanism of B[a]P-induced immune system disorder in bivalves.

Bioaccumulation and function analysis of glutathione S-transferase isoforms in Manila clam Ruditapes philippinarum exposed to different kinds of PAHs

This study analyzed the function of different glutathione S-transferase (GST) isoforms and detoxification metabolism responses in Manila clam, Ruditapes philippinarum, exposed to 4 kinds of polycyclic aromatic hydrocarbons (PAHs) single, and their mixtures for 15 days under laboratory conditions. 13 kinds of GSTs in R. philippinarum were classified, and the results of tissue distribution indicated that 12 kinds of GSTs (except GST sigma 3) expressed most in digestive glands. We detected the mRNA expression levels of aryl hydrocarbon receptor signaling pathway, and detoxification system in digestive glands of clams exposed to benzo[a]pyrene (BaP), chrysene (CHR), benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), and BaP + CHR + BaA + BbF, respectively. Among these genes, we selected GST-sigma, GST-omega and GST-pi as potential indicators to BaP; GST-sigma, GST-A and GST-rho to CHR; GST-pi, GST-sigma, GST-A, GST-rho and GST-microsomal to BaA; GST-theta and GST-mu to BbF; while GST-pi and GST-mu to the mixture of BaP, CHR, BaA and BbF. Additionally, the bioaccumulation of PAHs in tissues increased remarkably over time, and showed an obvious dose-effect. Under the same concentration, the bioaccumulation in single exposure group was higher than that in mixture group, and the bioaccumulation of PAHs in tissues with different concentrations of stress was irregular. The results revealed the metabolic differences and bioaccumulation rules in clams exposed to four kinds of PAHs, and provided more valuable information for the PAHs risk assessment.

Oyster Crassostrea gigas, a good model for correlating viral and chemical contamination in the marine environment

To establish a relationship between viruses and chemicals, they were analysed in oyster Crassostrea gigas from an Italian experimental station. The chemicals concentrations were: Σ6 NDL-PCBs 0.82-7.12 ng g^-1; BaP LOQ (<0.2 μg kg^-1) to 1.2 μg kg^-1; PAH4 LOQ (<0.2 μg kg^-1) to 9.8 μg kg^-1; Cd 0.073-0.365 mg kg^-1; Pb 0.010-0.487 mg kg^-1; and Hg < LOQ (0.089 mg kg^-1). The viruses identified included: noroviruses (NoVGI/GII), astrovirus (AsV), rotavirus (RV), adenovirus (AdV), and sapovirus (SaV), while hepatitis A, hepatitis E, and Aichi viruses were not detected. Significant correlations were observed for NDL-PCBs with NoVGI, NoVGII, and AdV; BaP and PAH4 with NoVGI and AsV; Cd with RV; Pb with NoVGI and AsV; PAHs with Pb; AsV with NoVGI; and AdV with NoVGII. The study indicated as C. gigas is a model for correlating pollutants and foodborne viruses, whose co-presence may represent an additional food safety risk.

Impact of Polycyclic Aromatic Hydrocarbon Accumulation on Oyster Health

In the past decade, the Deepwater Horizon oil spill triggered a spike in investigatory effort on the effects of crude oil chemicals, most notably polycyclic aromatic hydrocarbons (PAHs), on marine organisms and ecosystems. Oysters, susceptible to both waterborne and sediment-bound contaminants due to their filter-feeding and sessile nature, have become of great interest among scientists as both a bioindicator and model organism for research on environmental stressors. It has been shown in many parts of the world that PAHs readily bioaccumulate in the soft tissues of oysters. Subsequent experiments have highlighted the negative effects associated with exposure to PAHs including the upregulation of antioxidant and detoxifying gene transcripts and enzyme activities such as Superoxide dismutase, Cytochrome P450 enzymes, and Glutathione S-transferase, reduction in DNA integrity, increased infection prevalence, and reduced and abnormal larval growth. Much of these effects could be attributed to either oxidative damage, or a reallocation of energy away from critical biological processes such as reproduction and calcification toward health maintenance. Additional abiotic stressors including increased temperature, reduced salinity, and reduced pH may change how the oyster responds to environmental contaminants and may compound the negative effects of PAH exposure. The negative effects of acidification and longer-term salinity changes appear to add onto that of PAH toxicity, while shorter-term salinity changes may induce mechanisms that reduce PAH exposure. Elevated temperatures, on the other hand, cause such large physiological effects on their own that additional PAH exposure either fails to cause any significant effects or that the effects have little discernable pattern. In this review, the oyster is recognized as a model organism for the study of negative anthropogenic impacts on the environment, and the effects of various environmental stressors on the oyster model are compared, while synergistic effects of these stressors to PAH exposure are considered. Lastly, the understudied effects of PAH photo-toxicity on oysters reveals drastic increases to the toxicity of PAHs via photooxidation and the formation of quinones. The consequences of the interaction between local and global environmental stressors thus provide a glimpse into the differential response to anthropogenic impacts across regions of the world.

The toxic impacts of microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) on haematic parameters in a marine bivalve species and their potential mechanisms of action

Microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) are universally detected in the marine ecosystem and may exert adverse impacts on marine species. Although under realistic pollution scenarios, PAH pollution usually occurs as a mixture of different PAH compounds, the toxic impacts of PAH mixtures on marine organisms remain largely unknown to date, including their interactions with other emergent pollutants such as MPs. In this study, the single and combined toxic impacts of polystyrene MPs and a mixture of PAHs (standard mix of 16 representative PAHs) on haematic parameters were evaluated in the blood clam Tegillarca granosa. Our data demonstrated that blood clams treated with the pollutants examined led to decreased total haemocyte count (THC), changed haematic composition, and inhibited phagocytosis of haemocytes. Further analyses indicated that MPs and a mixture of PAHs may exert toxic impacts on haematic parameters by elevating the intracellular contents of reactive oxygen species (ROS), giving rise to lipid peroxidation (LPO) and DNA damage, reducing the viability of haemocytes, and disrupting important molecular signalling pathways (indicated by significantly altered expressions of key genes). In addition, compared to clams treated with a single type of pollutant, coexposure to MPs and a mixture of PAHs exerted more severe adverse impacts on all the parameters investigated, indicating a significant synergistic effect of MPs and PAHs.

Damages to biological macromolecules in gonadal subcellular fractions of scallop Chlamys farreri following benzo[a]pyrene exposure: Contribution to inhibiting gonadal development and reducing fertility

Benzo[a]pyrene (B[a]P), a representative polycyclic aromatic hydrocarbon (PAH) compound in marine ecosystem, has great potential for chronic toxicity to marine animals. It is becoming increasingly apparent that reproductive system is the major target of B[a]P, but the adverse effects of B[a]P on subcellular fractions in bivalve gonads have not been elucidated. Scallops Chlamys farreri are used as the experimental species since they are sensitive to environmental pollutants. This study was conducted to investigate how B[a]P affected the gonadal subcellular fractions, including plasma membrane, nucleus, mitochondria and microsome in scallops, and whether subcellular damages were related to reproductive toxicity. The results showed that mature gametes' counts were significantly decreased in B[a]P-treated scallops. Three biological macromolecules (viz., DNA, lipids and proteins) in gonadal subcellular fractions obtained by differential centrifugation suffered damages, including DNA damage, lipid peroxidation and protein carbonylation in B[a]P treatment groups. Interestingly, mitochondria and microsome were more vulnerable to lipid peroxidation and protein carbonylation than plasma membrane and nucleus, meanwhile males were more susceptible to DNA damage than females under B[a]P exposure. In addition, histological analysis showed that B[a]P delayed gonadal development in C. farreri. To summarize, our results indicated that B[a]P caused damages to biological macromolecules in gonadal subcellular fractions and then induced damages to gonadal tissues of C. farreri, which further inhibited gonadal development and ultimately leaded to reduction in fertility. This study firstly reports the impacts of PAHs on subcellular fractions in bivalves and their relationship with reproductive toxicity. Moreover, exposure of reproductive scallops to B[a]P leads to defects in reproduction, raising concerns on the possible long-term consequences of PAHs for natural populations of bivalves.

GYY4137 protected the integrity of the blood-brain barrier via activation of the Nrf2/ARE pathway in mice with sepsis

Injury to the blood-brain barrier (BBB) plays a vital role in sepsis-associated encephalopathy (SAE), which is one of the most common complications of sepsis. GYY4137, a new synthetic compound of hydrogen sulfide (H₂ S), has extensive biological benefits. In this study, we focused on the protective effects of GYY4137 on the BBB in septic mice and the underlying mechanisms. The results suggested that whether administrated at the same time or 3 hours after LPS injection, GYY4137 both significantly alleviated the clinical symptoms and the long-term prognosis. Besides, GYY4137 improved the pathological abnormalities of septic mice. Moreover, the degradation of tight junctions in the BBB was considerably inhibited by GYY4137. In addition, GYY4137 significantly attenuated inflammation and apoptosis in the brain. Furthermore, GYY4137 activated the Nrf2/ARE pathway through the sulfhydrylation of Keap1 and inhibited oxidative stress. ML385, the specific inhibitor of Nrf2, significantly reversed the protective effects of GYY4137 in sepsis mice. In conclusion, this study indicated that through the sulfhydrylation of Keap1, GYY4137 activated the Nrf2/ARE pathway and exerted anti-inflammatory, anti-apoptotic and antioxidant effects in septic mice that consequently protected the integrity of the BBB and improved the clinical outcome of sepsis. Our findings suggest that GYY4137 might be a promising agent for the treatment of SAE.

Modeling the relationship between emerging and persistent organic contaminants in water, sediment and oysters from a temperate lagoon

The concentrations of emerging and persistent organic contaminants (EPOC) in oysters (C_O) from Aveiro Lagoon are represented as a function of their concentrations in water (C_W) and sediment (C_S) using linear and generalized additive models (LM, GAM). Additionally, four sampling seasons, octanol/water partition coefficients (K) and type of EPOC (pyrethroids, flame-retardants, musks, UV filters, polycyclic aromatic hydrocarbons, others) are included in the models. The probabilities of detection of EPOC in water, sediment and oysters are analyzed by GAM. The behavior of contaminants in water is determined by K with a clear seasonal trend. Sediments are reservoirs for hydrophobic compounds with less seasonal variation. Seasonal changes are found for C_O, the last being determined additively both by C_W and hydrophobicity from one side and by C_S and type of contaminants from the other side. The seasonal change of EPOC concentration in water, sediment and oysters is specific for each contaminant type.

Sperm quality assessment in Ficopomatus enigmaticus (Fauvel, 1923): Effects of selected organic and inorganic chemicals across salinity levels

Contamination by organic and inorganic compounds remains one of the most complex problems in both brackish and marine environments, causing potential implications for the reproductive success and survival of several broadcast spawners. Ficopomatus enigmaticus is a tubeworm polychaete that has previously been used as a model organism for ecotoxicological analysis, due to its sensitivity and ecological relevance. In the present study, the effects of five trace elements (zinc, copper, cadmium, arsenic and lead), one surfactant (sodium dodecyl sulfate, SDS) and one polycyclic aromatic hydrocarbon (benzo(a)pyrene, B(a)P) on the sperm quality of F. enigmaticus were investigated. Sperm suspensions were exposed in vitro to different concentrations of each selected contaminant under four salinity conditions (10, 20, 30, 35). Possible adverse effects on sperm function were assessed by measuring oxidative stress, membrane integrity, viability and DNA damage. Sperm quality impairments induced by organic contaminants were more evident than those induced by inorganic compounds. SDS exerted the largest effect on sperm. In addition, F. enigmaticus sperm showed high tolerance to salinity variation, supporting the wide use of this species as a promising model organism for ecotoxicological assays. Easy and rapid methods on polychaete spermatozoids were shown to be effective as integrated sperm quality parameters or as an alternative analysis for early assessment of marine and brackish water pollution.

Zingerone [4-(3-Methoxy-4-hydroxyphenyl)-butan-2] Attenuates Lipopolysaccharide-Induced Inflammation and Protects Rats from Sepsis Associated Multi Organ Damage

The present investigation aimed to evaluate the protective effect of Zingerone (ZIN) against lipopolysaccharide-induced oxidative stress, DNA damage, and cytokine storm in rats. For survival study the rats were divided into four groups (n = 10). The control group was treated with normal saline; Group II received an intraperitoneal (i.p) injection (10 mg/kg) of LPS as disease control. Rats in Group III were treated with ZIN 150 mg/kg (p.o) 2 h before LPS challenge and rats in Group IV were given ZIN only. Survival of the rats was monitored up to 96 h post LPS treatment. In another set, the animals were divided into four groups of six rats. Animals in Group I served as normal control and were treated with normal saline. Animals in Group II were treated with lipopolysaccharide (LPS) and served as disease control. Group III animals were treated with ZIN 2 h before LPS challenge. Group IV served as positive control and were treated with ZIN (150 mg/kg orally). The blood samples were collected and used for the analysis of biochemical parameters like alanine transaminase (ALT), alkaline phosphatase (ALP), aspartate transaminase (AST), blood urea nitrogen (BUN), Cr, Urea, lactate dehydrogenase (LDH), albumin, bilirubin (BIL), and total protein. Oxidative stress markers malondialdehyde (MDA), glutathione peroxidase (GSH), myeloperoxidase (MPO), and (DNA damage marker) 8-OHdG levels were measured in different organs. Level of nitric oxide (NO) and inflammatory markers like TNF-α, IL-1ß, IL-1α, IL-2, IL-6, and IL-10 were also quantified in plasma. Procalcitonin (PCT), a sepsis biomarker, was also measured. ZIN treatment had shown significant (p < 0.5) restoration of plasma enzymes, antioxidant markers and attenuated plasma proinflammatory cytokines and sepsis biomarker (PCT), thereby preventing the multi-organ and tissue damage in LPS-induced rats also confirmed by histopathological studies of different organs. The protective effect of ZIN may be due to its potent antioxidant potential. Thus ZIN can prevent LPS-induced oxidative stress as well as inflammatory and multi-organ damage in rats when administered to the LPS treated animals.

The mechanism of Mitogen-Activated Protein Kinases to mediate apoptosis and immunotoxicity induced by Benzo[a]pyrene on hemocytes of scallop Chlamys farreri in vitro

Benzo [a]pyrene (B [a]P) has received widespread attention for serious pollution in the sea, which may reduce immunity and lead to the outbreak of disease in bivalves. However, the mechanism of immunotoxicity induced by B [a]P in bivalves was still unclear. Previous studies have found that Mitogen-Activated Protein Kinases (MAPKs) including three classic pathways (ERK, p38 and JNK) play an important role in mediating this process. Thus, in order to explore the mechanism of immunotoxicity induced by B [a]P in scallop Chlamys farreri, hemocytes were treated with PD98059 (ERK inhibitor), SB203580 (p38 inhibitor) and SP600125 (JNK inhibitor) for 1 h and then incubation with B [a]P for 24 h at 1 μg/mL. Indexes including oxidative damage, apoptotic rate, and immune indicators were detected in the present study. The results showed that the increase of Reactive Oxygen Species (ROS) and DNA damage induced by B [a]P was inhibited with PD98059 and SB203580. Besides, lysosomal membrane stability (LMS) damage was promoted by PD98059, while it was opposite when treated with SB203580. Moreover, the ascended apoptosis rate induced by B [a]P was increased significantly after treatment with PD98059, but it was remarkably attenuated by SB203580 and SP600125. However, the opposite pattern was showed in phagocytosis compared with apoptosis rate in all of three inhibitors. In addition, antibacterial activity and bacteriolytic activity were enhanced by SB203580 while inhibited by PD98059. Therefore, these results showed that MAPKs directly or indirectly mediate the decrease of oxidative damage, apoptosis and immune defense ability of C. farreri hemocytes, which suggesting ERK/p38/JNK pathways have different functions in the apoptosis and immunity of C. farreri hemocytes after B [a]P exposure. In conclusion, this study intended to enrich the theoretical basis for immunotoxicology of bivalves exposed to pollutants.

Lead toxicity on a sentinel species subpopulation inhabiting mangroves with different status conservation

Lead is a priority pollutant introduced in the aquatic environment by different sources commonly located in estuarine regions, such as ports, marinas and industries. Environmental agencies around the world set the maximum allowable concentration of lead in effluents, surface water and sediment, but few studies reported its accumulation and chronic toxicity in mangrove benthic invertebrates using concentrations believed to be safe. In the case of Brazilian mangrove environments, Ucides cordatus is a crab species of choice to be used in bioaccumulation studies. We have assessed biomarkers' responses (DNA strand breaks, micronucleated cells, metallothioneins, enzymatic activity of aminolevulinic acid dehydratase and neutral red retention time) and the total bioaccumulation in six tissues of U. cordatus crabs resident to mangrove areas under different conservation status during a 28-day period bioassay. We also investigated Pb subcellular partition and biomarkers' responses using a supposedly safe concentration (10 μg L^-1). During the Pb exposure, the highest concentration of Pb was observed in crab gills. Crabs also showed a high ability to allocate Pb in detoxified forms. Multivariate analysis pointed out that bioaccumulation (total, active and detoxified) is linked to biomarkers. Even in supposedly safe dosage, U. cordatus triggered its defense mechanisms expressing more metallothioneins and presented relevant cyto-genotoxic damage. Our data suggest the development of biological tolerance to Pb in crabs from polluted areas. Our results provided a new insight about lead toxicity even at concentrations considered environmentally safe, which could support new strategies to manage estuarine areas considering their respective conservation status.

Bioaccumulation and oxidative damage of polycyclic aromatic hydrocarbon mixtures in Manila clam Ruditapes philippinarum

The aim of this study was to investigate the bioaccumulation and oxidative damage of Manila clam, Ruditapes philippinarum, exposed to four selected mixtures of polycyclic aromatic hydrocarbons (PAHs; benzo (a) pyrene (BaP), benzo (a) anthracene (BaA), benzo (b) fluoranthene (BbF), and chrysene (Chr) in equal proportion. For this purpose, clams were exposed to PAHs (BaP:BbF:BaA:Chr = 1:1:1:1) at different concentrations (0.05, 0.5, and 5 μg/L) for 21 days, followed by a 15-day depuration period. All four PAHs accumulated in the gill, digestive gland, adductor muscle, and soft tissue of Manila clams, and all PAH treatment groups showed clear time and dose dependence. The decreasing order of bioaccumulation for the four PAHs in the exposure experiment was Chr > BaA > BaP > BbF. Moreover, the order of PAH bioaccumulation for the four tissues during the whole experiment was digestive gland > gill > soft tissues > adductor muscles. Although the initial concentrations of the four PAHs were the same, the final accumulated contents were different. Therefore, we also determined the detoxification processes of the four PAH mixtures in gills and digestive glands. The bioaccumulation of Chr was higher than the other three PAHs, probably because clams have a lower metabolic capacity for Chr than for BaP, BbF, and BaA. Exposure to PAH mixtures can result in oxidative damage, as indicated by the fact that DNA strand breaks, lipid peroxidation (LPO), and protein carbonyl (PC) were induced significantly (P < 0.05), except in the low-dose groups of PAHs, and different trends were detected with time of exposure. According to the correlation analysis, aryl hydrocarbon hydroxylase, glutathione s-transferase, superoxide dismutase, DNA strand break, PC, and LPO in both the gill and digestive gland are potential early indicators of PAH mixtures. We investigated the accumulation rules of R. philippinarum exposed to the selected PAHs and screened the potential biomarkers. The results of our study provide important scientific information for the purpose of monitoring marine pollution.

The effects of ultraviolet radiation and climate on oil toxicity to coral reef organisms - A review

Oil pollution remains a significant local threat to shallow tropical coral reef environments, but the environmental conditions typical of coral reefs are rarely considered in oil toxicity testing and risk assessments. Here we review the effects of three environmental co-factors on petroleum oil toxicity towards coral reef organisms, and show that the impacts of oil pollution on coral reef taxa can be exacerbated by environmental conditions commonly encountered in tropical reef environments. Shallow reefs are routinely exposed to high levels of ultraviolet radiation (UVR), which can substantially increase the toxicity of some oil components through phototoxicity. Exposure to UVR represents the most likely and harmful environmental co-factor reviewed here, leading to an average toxicity increase of 7.2-fold across all tests reviewed. The clear relevance of UVR co-exposure and its strong influence on tropical reef oil toxicity highlights the need to account for UVR as a standard practice in future oil toxicity studies. Indeed, quantifying the influence of UVR on toxic thresholds of oil to coral reef species is essential to develop credible oil spill risk models required for oil extraction developments, shipping management and spill responses in the tropics. The few studies available indicate that co-exposure to elevated temperature and low pH, both within the range of current daily and seasonal fluctuations and/or projected under continued climate change, can increase oil toxicity on average by 3.0- and 1.3-fold, respectively. While all three of the reviewed environmental co-factors have the potential to substantially increase the impacts of oil pollution in shallow reef environments, their simultaneous effects have not been investigated. Assessments of the combined effects of oil pollution, UVR, temperature and low pH will become increasingly important to identify realistic hazard thresholds suitable for future risk assessments over the coming century.

Zingerone prevents lead-induced toxicity in liver and kidney tissues by regulating the oxidative damage in Wistar rats

Among the heavy metal poisonings, lead is considered as a major toxic metal causing hematological, neurological, immunological, hepatic, and renal dysfunctions. Lead causes inhibition of ALAD leading to the ALA accumulation inside the cells. Lead also leads to disruption of the anti-oxidative enzyme system, organ function, and lipid membranes of the cell causing oxidative stress. Zingerone, a phenolic alkanone, is an active edible ingredient present in the ginger that possess varied pharmacological properties. The aim of our study was to evaluate the protective effect of zingerone in lead-induced toxicity in wistar rats. ALAD concentration was improved in kidney and liver tissues treated with zingerone. Protective effect of zingerone was observed in terms of significant improvement in kidney and liver histology, anti-oxidant enzyme activity (CAT, SOD, GPx, and GR), organ function parameters, lipid profile, and decreased level of LPO. Therefore, zingerone pretreatment can be a promising agent for alleviation of lead-induced oxidative damage in cells. PRACTICAL APPLICATIONS: Published reports have revealed that consumption of certain bioactive nutrients for example, flavonoids, mineral elements, and vitamins can offer defense from the environmental lead contamination. Zingerone is a strong anti-oxidant, with very less side effects and has exceptional property of scavenging free radicals, hence reducing the oxidative stresses. This fundamental property of zingerone can alone help in countering the heavy metal toxicity. Different groups have published reported numerous properties of zingerone but as per our understanding till date no study about alleviation of lead toxicity by zingerone in animal model has been undertaken. Hence, we conducted this research to explore the preventive effect of zingerone in lead induced kidney and liver toxicity. The outcome of our study shows potent anti-oxidant effect and ALAD modulatory property of zingerone which makes it suitable edible candidate for use in countering lead toxicity.

Polycyclic aromatic hydrocarbons and potentially toxic elements in seafood from the Persian Gulf: presence, trophic transfer, and chronic intake risk assessment

High bioavailability of man-made pollutants in marine environments raises serious concern regarding the safety of seafood. In the present study, the presence, trophic transfer, and risks of polycyclic aromatic hydrocarbons (PAHs), and potentially toxic elements (PTEs) in 170 benthic marine organisms (87 prawn; 28 crab; 55 fish) from the Persian Gulf were investigated. Among investigated species, E. coioides displayed the lowest level of metal pollution index (MPI), while P. armatus and P. semisulcatus showed the highest level of MPI and total PAHs, respectively. Principal component biplot exhibited a significant association of PTEs (except Hg) and PAHs in less motile benthic species. The results of trophic transfer investigation revealed that PTEs (except Hg) and PAHs were not biomagnified in the studied organisms through diet. However, Hg biomagnification factors greater than 1 indicated trophic transfer of mercury. In order to gain nutritional benefits of seafood, consumption of two fish/prawn meals/week for adults (except vulnerable groups such as pregnant women) and one fish/prawn meals/week for children is recommended. However, lifelong consumption of crabs (P. armatus) may threaten human health. In addition, the maximum allowable fish consumption rate (CR_lim) for studied fish is 120 g fish/day for adults and 30 g fish/day for children. In the case of prawns, the safe dose is 30 and 10 g prawns/day for adults and children, respectively.

Mercury chloride exposure induces DNA damage, reduces fertility, and alters somatic and germline cells in Drosophila melanogaster ovaries

Mercury exposure has been shown to affect the reproductive system in many organisms, although the molecular mechanisms are still elusive. In the present study, we exposed Drosophila melanogaster Canton-S adult females to concentrations of 0 mM, 0.1 mM, 0.3 mM, 3 mM, and 30 mM of mercury chloride (HgCl₂) for 24 h, 48 h, or 72 h to determine how mercury could affect fertility. Alkaline assays performed on dissected ovaries showed that mercury induced DNA damage that is not only dose-dependent but also time-dependent. All ovaries treated for 72 h have incorporated mercury and exhibit size reduction. Females treated with 30 mM HgCl₂, the highest dose, had atrophied ovaries and exhibited a drastic 7-fold reduction in egg laying. Confocal microscopy analysis revealed that exposure to HgCl₂ disrupts germinal and somatic cell organization in the germarium and leads to the aberrant expression of a germline-specific gene in somatic follicle cells in developing egg chambers. Together, these results highlight the potential long-term impact of mercury on germline and ovarian cells that might involve gene deregulation.

Mangrove metal pollution induces biological tolerance to Cd on a crab sentinel species subpopulation

Metals are persistent pollutants, able to accumulate in the biota and magnify in trophic web. In the specific case of cadmium contamination, it has been the subject of considerable interest in recent years because of its biological effects and it is one of major pollutant in estuarine areas. Ucides cordatus is considered a mangrove local sentinel crab species in Brazil and there are previous studies reporting crab subpopulations living from pristine to heavily metal impacted areas in São Paulo coast (Southeastern Brazil). Taking into account the background knowledge about these subpopulations, we proposed the hypothesis that crabs from a highly polluted mangrove (Cubatão - CUB) have developed biological tolerance to cadmium compared to animals from an Environmental Protected Area (Jureia - JUR). Aiming to verify this hypothesis, we have investigated total bioaccumulation and subcellular partition of Cd, besides biomarkers' responses during a long-term exposure bioassay (28 days, with weekly sampling) using a supposedly safe Cd concentration (0.0022 mg L^-1). Specimens from the pristine area (JUR) accumulated higher total Cd, as such as in its biologically active form in gills. Animals living in the polluted site (CUB) presented higher amounts of Cd in the mainly detoxifying tissue (hepatopancreas), which could be considered a pathway leading to tolerance for this metal. Multivariate analysis indicated that bioaccumulation (active, detoxified and total Cd) is linked to geno-cytotoxic damages. CUB subpopulation was considered more tolerant since it presented proportionally less damage and more capacity to allocate Cd in the main detoxifying forms and tissues.

The effects of benzo[a]pyrene on the composition of gut microbiota and the gut health of the juvenile sea cucumber Apostichopus japonicus Selenka

The gut microbiota is essential for health and physiological functions in the host organism. However, the toxicological evaluation of environmental pollutants on the gut microbiota is still insufficient. In the present study, the juvenile sea cucumber Apostichopus japonicus was exposed for 14 days to Benzo[a]pyrene (BaP), which is a model polycyclic aromatic hydrocarbon (PAH), at four different concentrations (0, 0.5, 5, and 25 μg/L). We analyzed the intestinal microbial community of A. japonicas using 16S rRNA gene amplicon sequencing. Our results demonstrate that BaP exposure caused alterations to the microbiome community composition in sea cucumbers. At the phylum level, Planctomycetes were significantly more abundant in BaP exposure groups at 14 d compared with the control group, and the abundance of Proteobacteria and Bacteroidetes increased while the abundance of Firmicutes decreased following BaP exposure. At the genus level, multiple beneficial and autochthonous genera declined in the BaP treatment groups compared to the control, including Lactococcus, Bacillus, Lactobacillus, Enterococcus, Leuconostoc and Weissella; however, a bloom of alkane-degrading bacteria was found in BaP-exposed guts and included Lutibacter, Pseudoalteromonas, Polaribacter, Rhodopirellula and Blastopirellula. Furthermore, histological morphology, enzymatic activity and gene expression analysis revealed that BaP exposure also negatively impacted gut structure and function and presented as inflammation or atrophy, oxidative stress and immune suppression in sea cucumber intestines. Collectively, these findings provide insights into the toxic effects of BaP exposure on A. japonicas associated with intestinal microbiota and health.

Copper-induced H2O2 accumulation confers larval tolerance to xanthotoxin by modulating CYP6B50 expression in Spodoptera litura

In the plant-insect arms race, plants synthesize toxic compounds to defend against herbivorous insects, whereas insects employ cytochrome P450 monooxygenases (P450s) to detoxify these phytotoxins. As ubiquitous environmental contaminants, heavy metals can be easily absorbed by plants and further accumulated in herbivorous insects through the food chains, resulting in tangible consequences for plant-insect interactions. However, whether heavy metals can influence P450 activities and thereby cause further effects on larval tolerance to phytotoxins remains unknown. In this study, we shown that prior exposure to copper (Cu) enhanced larval tolerance to xanthotoxin in Spodoptera litura, a major polyphagous pest of agriculture. P450 activities were induced in larvae exposed to Cu or xanthotoxin, and a midgut specific expressed P450 gene, CYP6B50 was cross-induced after exposure to these two toxic xenobiotics. Knocking down CYP6B50 by RNA interference (RNAi) rendered the larvae more sensitive to xanthotoxin. As defense against oxidative stress following metal exposure has been demonstrated to affect insecticide resistance, the reactive oxygen species (ROS) generation and antioxidant enzyme activities were assessed. Cu exposure caused the accumulation of hydrogen peroxide (H₂O₂) and enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD) in larval midgut. In addition, two antioxidant response elements (AREs) were identified from the CYP6B50 promoter, indicating that Cu-induced CYP6B50 expression may be related to the ROS burst. Application of ROS scavenger N-acetylcysteine (NAC) effectively suppressed CYP6B50 expression, inhibited P450 activities and impaired larval tolerance to xanthotoxin that had been induced by Cu. These results indicate that the increase in CYP6B50 expression regulated by Cu-induced H₂O₂ generation contributed to the enhancement of larval tolerance to xanthotoxin in S. litura. Ingestion of heavy metals from their host plants can inadvertently boost the counter-defense system of herbivorous insects to protect themselves against plant defensive toxins.

Persistent and emerging pollutants assessment on aquaculture oysters (Crassostrea gigas) from NW Portuguese coast (Ria De Aveiro)

The study aim was to determine a range of relevant persistent and emerging pollutants in oysters produced in an aquaculture facility located in an important production area, to assure their safety for human consumption. Pollutants, including 16 PAHs, 3 butyltins (BTs), 29 flame retardants (FRs, including organophosphate and halogenated FRs), 35 pesticides (including 9 pyrethroid insecticides) and 13 personal care products (PCPs, including musks and UV filters), were determined in oysters' tissues collected during one year in four seasonal sampling surveys. The seasonal environmental pollution on the production site was evaluated by water and sediment analysis. Furthermore, oysters' nutritional quality was also assessed and related with the consumption of healthy seafood, showing that oysters are a rich source of protein with low fat content and with a high quality index all year around. Results showed that most analysed pollutants were not detected either in oyster tissues or in environmental matrixes (water and sediments). The few pollutants detected in oyster tissues, including both regulated and non-legislated pollutants, such as a few PAHs (fluorene, phenanthrene, anthracene, fluoranthene, pyrene and indenopyrene), FRs (TPPO, TDCPP, DCP, BDE-47, BDE-209 and Dec 602) and PCPs (galaxolide, galaxolidone, homosalate and octocrylene), were present at low levels (in the ng/g dw range) and did not represent a significant health risk to humans. The observed seasonal variations related to human activities (e.g. tourism in summer) highlights the need for environmental protection and sustainable resource exploration for safe seafood production.

Antioxidant defenses at enzymatic and transcriptional levels in response to acute lead administration in Oxya chinensis

Lead (Pb) is known to be toxic to many organisms. Oxidative stress is a major mechanism of its toxicity. This research aims to investigate the effects of Pb on hydrogen peroxide (H₂O₂) and malonedialdehyde (MDA) contents, activities and mRNA levels of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)) after Oxya chinensis were acutely treated with lead acetate for 24 h. The results showed that the LD₅₀-24 h value of lead acetate to O. chinensis was 1541.89 (1431.19-1655.77) μg g^-1 body H₂O₂ and MDA contents were elevated after Pb administration, which suggested that Pb induced the overproduction of ROS and caused oxidative stress. SOD activities were significantly inhibited 40.42% of the control by 280 μg μL^-1 Pb. CAT activities were increased while GPx activities had no significant changes. Different types of antioxidant-related genes had various responses to Pb stress. The transcriptions of icCuZnSOD2 and ecCuZnSOD2 were significantly inhibited by different concentrations of Pb. MnSOD mRNA levels showed the concentration-dependent rise with the Pb concentrations increase. The expressions of ecCuZnSOD1, CAT1, and GPx were significantly up-regulated while the transcriptions of icCuZnSOD1 and CAT2 had no significant changes. Alteration of activities and mRNA expressions of antioxidant enzymes implied that Pb-induced antioxidant defenses were related to modifications at enzymatic and transcriptional levels. The profiles of antioxidant enzymes and H₂O₂ and MDA contents and relationships among the parameters indicated that the cooperation of multiple antioxidants rather than a single factor might be responsible for the antioxidant defenses against Pb stress.