A multi-biomarker approach in scallop Chlamys farreri to assess the impact of contaminants in Qingdao coastal area of China

Assessment of toxic metal pollution in Yueqing Bay and the extent of metal-induced oxidative stress in Tegillarca granosa raised in this water

Yueqing Bay is an important economic shellfish culture zone in Zhejiang Province, China. However, increased pollution in the water caused by toxic metals has led to the bioaccumulation of toxic metals in cockles such as Tegillarca granosa, and the consequence of toxic metal-associated toxicity in these animals. This study aimed to assess the concentration of toxic metals in the water and sediment in four different sites (Baisha, Qingjiang, Nanyue, and Wengyang) within Yueqing Bay and to evaluate the extent of metal bioaccumulation in T. granosa raised in the aquaculture farms located within the four sites, as well as the changes in biomarkers in T. granosa in response to the metals. The assessment was carried out at two different times of the year, January and July. The water and sediment samples taken from the aquaculture farms in Baisha (S1), Qingjiang (S2) and Nanyue (S3) were found to have a comprehensive toxic metal pollution index (Pc) <1, indicating that these farms were not polluted. However, the water and sediment samples taken from the aquaculture farm in Wengyang (S4) had a Pc between 1 and 2, indicating mild toxic metal pollution. The edible risk assessments (HQ) of T. granosa in all four farms were <1, and therefore, these cockles could be considered safe for human consumption. The toxic metal enrichment in T. granosa exhibited a strong correlation with the toxic metal content in the sediment. In all four farms, CAT and SOD activity levels in the visceral mass of T. granosa were higher than those found in the foot, and a significantly higher level of CAT activity was detected in July compared with January. Similarly, MDA and H2O2 contents in the visceral mass were also higher in July than in January. Tegillarca granosa individuals taken from S4 and S3 farms exhibited significantly higher levels of metallothionein (MT) mRNA and MDA compared with individuals from S1 and S2 farms. Furthermore, the levels of MDA and MT mRNA showed significant positive correlations with Cd, Cr, Hg, and Cu. Elevation of lipid peroxidation in these cockles coincided with increasing levels of endogenous antioxidants. The visceral mass of T. granosa and its MDA level could be used as a tissue indicator and a biochemical marker, respectively, for detecting toxic metal pollution. MT mRNA might also be used as a molecular marker of toxic metal pollution. The integrated biomarker response version 2 (IBRv2) values of the four aquaculture farms in Yueqing Bay showed the order S4 > S3 > S2 > S1, indicating that S4 had the most serious metal-induced stress. Furthermore, the IBRv2 values correlated with the Nemerow composite index (Pc) for all the cockles examined. Thus, as far as the contamination of aquaculture farms in Yueqing Bay by toxic metals is concerned, the aquaculture farm in Wengyang (S4) was mildly contaminated by toxic metals. However, the contamination was relatively low, presenting a low risk for the local population of T. granosa.

First characterization of seasonal variations in biomarkers baseline in Patella sp. from Mediterranean ports (North Corsica, France)

In port areas the identification of contamination sources is necessary for an efficient management. Biomonitoring provides information on the environmental impact of the pollutants. It is often difficult to differentiate the natural variations of biomarkers from those induced by pollution. The present study aims to define a baseline level for biochemical biomarkers in limpet (Patella sp.) collected in four North-Corsica port areas. Reference data for five biomarkers (superoxide dismutase, glutathione S-transferase, laccase, pyruvate kinase and acetylcholinesterase) were described in a model, using length of the limpet shell, temperature and salinity. The measured biomarkers responses on potentially polluted sites usually fell within the range of the expected values for an unaffected site, suggesting that a main part of the variations is explained by environmental conditions. Not included in the model, biological factors (sex, development stage, etc.), annual variation or other physico-chemical parameter could explain the variations in the model.

Toxicity response to benzo[α]pyrene exposure: Modulation of immune parameters of the bay scallop, Argopectenirradians

Bay scallops were exposed to four BaP concentrations (0.5, 1.0, 10 and 50 μg/L) for 72 h to elucidate their immune response. Immune parameters were evaluated by measuring nitric oxide (NO) levels in hemolymph. Additionally, we measured peptidoglycan recognition proteins (PGRP), fibrinogen-domain-containing protein (FReDC1), metallothionein (MT), and heat shock protein (HSP) 70 mRNA expression in digestive diverticula. NO as well as FReDC1 and MT expression in each BaP group increased significantly over time except for the BaP 0.5 group. The PGRP and HSP70 mRNA expression in the BaP 50 group increased in the range 6-24 h and then decreased. In situ hybridization also confirmed that there was higher MT mRNA expression in the BaP 50 group than in the control group at 72 h. Our results suggest that higher levels of BaP dampened scallop immune responses, while simultaneously reducing their ability to cope with oxidative stress and DNA damage. BaP exposure can be considered a potential immune inducer in bay scallop.

Assessment of the heavy metal levels and biomarker responses in the smooth scallop Flexopecten glaber from a heavily urbanized Mediterranean lagoon (Bizerte lagoon)

Marine heavy metal pollution is a worldwide serious issue. Like almost all Mediterranean lagoons, the Bizerte lagoon is highly urbanized and suffers from intensive anthropogenic pressure. In the present study, we screened the metal contamination and biomarker responses in the smooth scallop Flexopecten glaber inhabiting this vulnerable ecosystem. To this end, the concentrations of six heavy metals (HM) (i.e., Cu, Pb, Zn, Cd, Hg, and Fe) and a panel of biochemical endpoints including malondialdehyde (MDA), metallothioneins (MT), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) were determined in the gills and digestive gland across seasons (warm and cold) and sites (S1 and S2). The distribution of almost all analyzed metals in F. glaber tissues varied significantly between sites, seasons, and organs. The highest levels were recorded at S2 during the warm period. Moreover, the digestive gland was found to accumulate greater concentrations of HM than the gills. Marked spatio-temporal variations were also observed for oxidative stress biomarkers, mainly in the gills, while the digestive gland seems to be rather sensitive to seasonal variability. Particularly, we noticed that among the used biomarkers, MT did not show significant variations in the two tested organs across seasons and sites. From the obtained results, F. glaber appears as a sensitive organism to anthropogenic metal contamination and can be proposed as a promising bioindicator species for marine pollution.

Antioxidant activity of Far Eastern bivalves in their natural habitat

The activities of the key antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GP) and glutathione reductase (GR) as well as levels of reduced glutathione (GSH) and integral antioxidant activity (IAA), were studied in the digestive glands and gills of 14 bivalve species. Species and tissue differences of the antioxidant (AO) systems of the investigated mollusks were discussed in connection with their physiological and biochemical peculiarities. This article describes the role of the AO system of mollusks in adaptation to natural habitat conditions and shows the relationship of AO activity with the maximum habitat depth (MHD) and maximum lifespan (MLS) of these species.

The new PFAS C6O4 and its effects on marine invertebrates: First evidence of transcriptional and microbiota changes in the Manila clam Ruditapes philippinarum

There is growing concern for the wide use ofperfluorooctanoic acid (PFOA) because of its toxic effects on the environment and on human health. A new compound - the so called C6O4 (perfluoro ([5-methoxy-1,3-dioxolan-4-yl]oxy) acetic acid) - was recently introduced as one of the alternative to traditional PFOA, however this was done without any scientific evidence of the effects of C6O4 when dispersed into the environment. Recently, the Regional Agency for the Protection of the Environment of Veneto (Italy) detected high levels of C6O4 in groundwater and in the Po river, increasing the alarm for the potential effects of this chemical into the natural environment. The present study investigates for the first time the effects of C6O4 on the Manila clam Ruditapes philippinarum exposed to environmental realistic concentrations of C6O4 (0.1 µg/L and 1 µg/L) for 7 and 21 days. Furthermore, in order to better understand if C6O4 is a valid and less hazardous alternative to its substitute, microbial and transcriptomic alterations were also investigated in clams exposed to 1 µg/L ofPFOA. Results indicate that C6O4 may cause significant perturbations to the digestive gland microbiota, likely determining the impairment of host physiological homeostasis. Despite chemical analyses suggest a 5 times lower accumulation potential of C604 as compared to PFOA in clam soft tissues, transcriptional analyses reveal several alterations of gene expression profile. A large part of the altered pathways, including immune response, apoptosis regulation, nervous system development, lipid metabolism and cell membrane is the same in C6O4 and PFOA exposed clams. In addition, clams exposed to C6O4 showed dose-dependent responses as well as possible narcotic or neurotoxic effects and reduced activation of genes involved in xenobiotic metabolism. Overall, the present study suggests that the potential risks for marine organism following environmental contamination are not reduced by replacing PFOA with C6O4. In addition, the detection of both C6O4 and PFOA into tissues of clams inhabiting the Lagoon of Venice - where there are no point sources of either compounds - recommends a similar capacity to spread throughout the environment. These results prompt the urgent need to re-evaluate the use of C6O4 as it may represent not only an environmental hazard but also a potential risk for human health.

Integrated transcriptomics and metabolomics analyses reveal benzo[a]pyrene enhances the toxicity of mercury to the Manila clam, Ruditapes philippinarum

Mercury (Hg²⁺) and benzo[a]pyrene (BaP) are ubiquitous and persistent pollutants with multiple toxicities in bivalve molluscs. Here, the toxicological responses in the gills of Manila clams, Ruditapes philippinarum, to Hg²⁺ (10 μg L^-1), BaP (3 μg L^-1), and their mixture were analysed using transcriptomics and metabolomics approaches. Comparisons of the transcriptomes and metabolomes of Hg²⁺-and/or BaP-treated clams with control animals revealed the involvement of the detoxification metabolism, immune defence, energy-related pathways, and osmotic regulation in the stress response of R. philippinarum. Exposure to Hg²⁺ alone primarily enhanced the detoxification and energy metabolic pathways by significantly increasing the expression of genes associated with heat-shock proteins and oxidative phosphorylation. However, co-exposure to Hg²⁺ and BaP caused greater immunotoxicity and disrupted detoxification metabolism, the TCA cycle, glycolysis, and ATP generation. The expression levels of cytochrome P450 1A1 (CYP1A1), multidrug resistance-associated protein 1 (MRP1), and myosin (MYO), and the activity of electron transport system (ETS) in gills were detected, supporting the underlying toxic mechanisms of Hg²⁺ and BaP. We suggest that the presence of BaP enhances the toxicity of Hg²⁺ by 1) hampering the detoxification of Hg²⁺, 2) increasing the immunotoxicity of Hg²⁺, and 3) constraining energy availability for clams.

Toxic effect of p-chloroaniline and butyl acrylateon Nannochloropsis oculata based on water samples from two sea areas

To compare the influence of water samples collected from various areas on toxic effect of HNS, we examined the toxic effect of two commonly found HNS: p-chloroaniline and butyl acrylate, on Nannochloropsis oculata cultured in seawater collected from Laizhou bay and Jiaozhou bay (China). The results showed that both p-chloroaniline and butyl acrylate had significant toxic effect on N. oculata cultured in both water samples. P-chloroaniline inhibited its net oxygenation rate and oxygen consumption rate. Butyl acrylate inhibited the net oxygenation rate whereas significantly stimulated oxygen consumption rate. Performance of N. oculata changed between two water samples under same level of p-chloroaniline and butyl acrylate. The net oxygenation rate of N. oculata cultured in the seawater from the Jiaozhou bay increased by 11.60 %, the oxygen consumption rate increased by 26.91 %, algae cell growth decreased by 16.83 %, compared to those from Laizhou bay. The Fv/Fm of N. oculata cultured in Jiaozhou bay was more significantly inhibited at 0.5 and 2.0 mg L^-1 p-chloroaniline, while it was significantly inhibited at 5. 0 mg L^-1 of butyl acrylate, compared to those from Laizhou bay. Moreover, the toxic effect of both HNS on net oxygenation rate and oxygen consumption rate were significantly attenuated as the concentration increased. The growth inhibition of microalgae cultured in two seawater samples was more evident at 0.5 and 5.0 mg L^-1 p-chloroaniline than at 2.0 mg L^-1 p-chloroaniline,and the growth inhibition of microalgae cultured in two seawater samples was more evident at 2.0 and 5.0 mg L^-1 butyl acrylate than at 0.5 mg L^-1 butyl acrylate. These results indicated that toxic effect of p-chloroaniline and butyl acrylate on the growth of N. oculata was influenced by the pollutants in the two water samples. Consequently, a corresponding research on water sample is required in advance to increase accuracy of future ecological risk assessment of HNS.

Depuration cadmium on physiological status and biological response of Chlamys farreri using the combination of ZnSO4, EDTA-Na2 and sodium citrate

Effective removal of cadmium (Cd) from Chlamys farreri by introducing ZnSO₄, EDTA-Na₂, and sodium citrate into seawater has previously been reported. However, some mechanisms underlying this removal are not clear. To address this lack of clarity, the present study aimed to investigate the changes of Cd forms in Chlamys farreri from treatment of these additives and analyze the physiological and biochemical responses by comparing the changes over treatment time in Catalase (CAT), Superoxide dismutase (SOD), and Glutathione s-transferase (GST) activity, as well as Malonaldehyde (MDA) concentration and glycogen level. Three forms of Cd, including protein -Cd, liberated Cd, and amino acid/peptide -Cd, were found, and they were sorted according to their Cd content into the following groups: protein -Cd > liberated Cd > amino acid/peptide-Cd. The removal rates of the three forms of Cd were 43.2%, 59.5%, and 59.0%, respectively, using ZnSO₄ and EDTA-Na₂. Additionally, a significant increase in Zn content was observed, which may suggest that reduction of bound Cd was partly due to the displacement of Cd by Zn. Moreover, Cd depuration using the additives can mitigate oxidative stress only in the first 12 h. Glycogen content continued to reduce over time, inferring that the healthy status of Chlamys farreri under treatment of the additives containing Zn can only be maintained within 12 h for excreting Cd when linking these physiological responses with the ability of the additives to remove Cd only in a short time, i.e. 12 h. The results indicated that Cd should be removed from Chlamys farreri for practical reasons.

Antioxidant defenses of flame scallop Ctenoides scaber (Born, 1778) exposed to the water-soluble fraction of used vehicle crankcase oils

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This paper evaluated effects of a WSF-UVCO on the antioxidant responses of the scallop Lima scabra.

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The antioxidant defenses in L. scabra seem be highly sensitive to low doses of to WSF-UVCO.

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Digestive gland and gill show stronger antioxidant responses in L. scabra exposed to WSF-UVCO.

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L. scabra could be good sensor for screening pollutant impacts along the Caribbean coastline.

Used vehicle crankcase oils are a source of contamination in Caribbean marine environments and may alter the oxidative balance of organism that inhabiting coastal ecosystems. This paper aims to evaluate effects of a water-soluble fraction of used vehicle crankcase oils (WSF-UVCO) on the antioxidant responses of the flame scallop Ctenoides scaber. The organisms were exposed to ascending sublethal concentrations 0, 0.001, 0.01 and 0.1 % of WSF-UVCO in a static system of aquaria during one week. Subsequently activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) as well as concentrations of reduced glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) were determined in the digestive gland, adductor muscle and gills. SOD, CAT, GST and TBARS increased in digestive gland of organisms exposed to WSF-UVCO at medium and highest concentrations, with a concomitant decrease in GPX and GR activities. In adductor muscle CAT decreased, but GR rose with exposure to 0.01 and 0.1 % WSF-UVCO; in gills, GST rose through all WSF-UVCO concentrations, and SOD, CAT and GR increased only at 0.1 %. The fluctuations in antioxidant enzymes and GST activities point out possible adjustments to control ROS production and detoxification of xenobiotics. These biochemical responses may guarantee the oxidative balance in flame scallop during short term exposure to low concentrations of WSF-UVCO. C. scaber appears suitable as an experimental organism for evaluating biological risks of sublethal exposure to hazardous xenobiotics in tropical marine environments.

A verification of correlation between chemical monitoring and multi-biomarker approach using clam Ruditapes philippinarum and scallop Chlamys farreri to assess the impact of pollution in Shandong coastal area of China

Biogeochemical monitoring coupled with multi-biomarker approach were performed for the assessment of marine environment, using clam Ruditapes philippinarum and scallop Chlamys farreri to indicate contamination status in sediments and seawater respectively. The bivalves were collected from three stations, Jiaozhou Bay, Rushan Bay and Laizhou Bay, of Shandong coastal area. A series of contaminants (PAHs and TBBPA) and biomarkers (AhR, EROD, GST, SOD, GPx, CAT, DNA damage) were measured. Multi-biomarker pollution index (MPI) and integrated biomarker response (IBR) were carried out to evaluate contamination status and both indexes showed that Rushan Bay was most polluted, where the pollution level of sediments reached "highly polluted" in August, followed by Jiaozhou Bay and Rushan Bay which reached "lightly polluted". The correlation of IBR values with contaminants' concentrations was verified through the Pearson correlation coefficient (p < 0.05), consolidating this scientific assessment method for marine environment.

Polycyclic aromatic hydrocarbons (PAHs) in marine organisms from two fishing grounds, South Yellow Sea, China: Bioaccumulation and human health risk assessment

Sediment and marine organism samples collected from Haizhou Bay and Lusi fishing ground in South Yellow Sea, China were analysed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 PAHs in marine organisms ranged from 127.43 to 350.53 ng/g dry weight (dw, Haizhou Bay fishing ground) and from 86.37 to 213.02 ng/g dw (Lusi fishing ground). The dominant compounds were 2- and 3-ring PAHs in marine organism tissues. The main PAH sources were found to be coal combustion. Specific habitat, feeding habit, trophic level and environmental differences may affect the PAH levels in marine organisms in our study area. The biota-sediment accumulation factor (BSAF) decreased with increasing PAH log K_ow and BSAF values might differ in response to various environmental conditions and species. The excess cancer risk from PAH-contaminated seafood consumption was slightly higher than the guideline value (10^-6), but much lower than the priority risk level (10^-4).

Depuration of cadmium from Chlamys farreri by ZnSO4, EDTA-Na2 and sodium citrate in short time

In view of high content of cadmium (Cd) in Chlamys farreri, a commercial edible shellfish species, depurating Cd from Chlamys farreri is an important topic nowadays, especially in short time. Therefore, three kinds of additives were introduced into seawater respectively, i.e. ZnSO₄, EDTA-Na₂, sodium citrate, to depurate Cd from Chlamys farreri. The alteration of Cd content in separate organs was investigated under several treatments with high depuration efficiency. The results showed that Cd was depurated exceeding 20% within 12 h by the combination of 0.15 g/L sodium citrate, 0.28 g/L ZnSO₄, and 0.42 g/L EDTA-Na₂. No obvious increase of Cd was observed in the adductor muscles, while Cd decreased in the other part, so the reduction of Cd in the whole organism of Chlamys farreri may occur. Cd reduction was found in the following organs: the digestive gland, kidney, gill, and mantle. Furthermore, Cd migration to gonad from other tissues was noticed.

Peruvian scallop Argopecten purpuratus: From a key aquaculture species to a promising biondicator species

The present study analyzed the Peruvian scallop Argopecten purpuratus and its food sources for metal and fatty acid concentrations in order to determine spatial and temporal differences. Metals such as copper (Cu), manganese (Mn), and zinc (Zn) in gills and iron (Fe) and Zn in sediments were the most significant explaining factors for spatial differentiations (degree of contamination), while for fatty acids, it was C14:0, C15:0, C16:0 and C18:0 in A. purpuratus' muscle and in its food sources, which explained more temporal differences (El Niño-Southern Oscillation (ENSO) effect). Gills, digestive gland and intestine were the tissues where metal accumulation was the highest in A. purpuratus. Cd in digestive gland was always high, up to ∼250-fold higher than in other tissues, as previously reported in other bioindicator species for metal pollution. Fatty acids were good biomarkers when annual comparisons were performed, while metals when locations were compared. ENSO 2017 played an important role to disentangle A. purpuratus' biological conditions and food sources. A. purpuratus from Paracas locations mostly showed higher metal concentrations in gills and digestive glands, and lower fatty acid concentrations in muscle than those from Sechura and Illescas Reserved Zone.

Copper effect on the biomarker state of the Mizuhopecten yessoensis tissues in the prespawning period

The aim of this study was to investigate the sensitivity of the marine scallop Mizuhopecten yessoensis to different copper concentrations (10 and 30 μgl-1) in the prespawning period. Reaction of the scallop to this effect was evaluated by a set of biomarkers, including general metabolism enzymes (acid and alkaline phosphatase activities - AcPase, ALP), and oxidative stress parameters (catalase antioxidant enzyme activity - CAT and levels of damage for DNA, lipids and proteins). Experiment results show that when copper is accumulated in tissues, enzyme activity changes are similar and have phasic character. The dynamics of these changes depends on the copper accumulation levels in tissues. Unlike enzyme reaction to copper accumulation, oxidative damage of biologic molecules changes in tissues in different ways. Copper enters into a scallop's organism, mainly through the gills, where there is a more expressed reaction of biomarkers compared to the digestive gland.

Aerobic cometabolism of tetrabromobisphenol A by marine bacterial consortia

The coastal environments worldwide are subjected to increasing TBBPA contamination, but current knowledge on aerobic biodegradability of this compound by marine microbes is lacking. The aerobic removal of TBBPA using marine consortia under eight different cometabolic conditions was investigated here. Results showed that the composition and diversity of the TBBPA-degrading consortia had diverged after 120-day incubation. Pseudoalteromonas, Alteromonas, Glaciecola, Thalassomonas, and Limnobacter were the dominant genera in enrichment cultures. Furthermore, a combination of beef extract- and peptone-enriched marine consortia exhibited higher TBBPA removal efficiency (approximately 60%) than the other substrate amendments. Additionally, Alteromonas macleodii strain GCW was isolated from a culture of TBBPA-degrading consortium. This strain exhibited about 90% of degradation efficiency toward TBBPA (10 mg L^-1) after 10 days of incubation under aerobic cometabolic conditions. The intermediates in the degradation of TBBPA by A. macleodii strain GCW were analyzed and the degradation pathways were proposed, involving β-scission, debromination, and nitration routes.

Biomarkers responses in Manila clam, Ruditapes philippinarum after single and combined exposure to mercury and benzo[a]pyrene

Physiological and biochemical responses in bivalves exposed to pollutants have proved a valuable tool to assess the health of organisms in aquatic ecosystems. The single and combined effects of mercury (Hg²⁺, 2 and 10 μg/L) and benzo[a]pyrene (BaP, 3 μg/L) on physiological and biochemical biomarkers in Manila clam, Ruditapes philippinarum were evaluated. Results showed that significant higher oxygen consumption (OR) and ammonia-N excretion rates (NR) together with significant lower ingestion rates (IR) were observed for the 10 μg/L Hg²⁺ or 3 μg/L BaP treatments compared to controls (P < 0.05). However, clam NR decreased significantly in response to the binary mixtures of 10 μg/L Hg²⁺ and 3 μg/L BaP (P < 0.05). Moreover, the levels of superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferases (GSTs), glutathione (GSH), acetylcholinesterase (AChE) and malondialdehyde (MDA) in the hepatopancreas of clams were induced substantially, whereas glycogen (GLY) contents were suppressed dramatically after Hg²⁺ and BaP exposure. Additionally, the integrated biomarker response (IBR) values measured showed significant increases in combination treatments and they were much higher than that in the Hg²⁺ treatment. This study will provide further information on the defense mechanism in the Manila clam after exposure to marine pollutants and may help evaluate the quality of the aquatic environment.

Corbicula fluminea gene expression modulated by CeO2 nanomaterials and salinity

Cerium dioxide nanomaterials (CeO₂ NMs) are used in different fields and incorporated in daily products. Several studies highlighted their effects on organism physiology, although molecular studies remain scarce. NM behavior is strongly dependent on the environment but few data are available using complex exposure media, raising the question of its environmental impacts. The aim of the present work was to assess the toxic potential of three CeO₂ NMs in Corbicula fluminea at a molecular level by RT-qPCR under a more realistic scenario of exposure, in a multistress context at two different salinities (1.5 and 15 psu). C. fluminea was exposed for 28 days to pulses of the three selected NMs (reference, manufactured, and aged manufactured). In bivalves, the gills and digestive gland are two key organs used for ecotoxicological studies. The expression change of 12 genes was measured in control organisms after 28 days in both organs, allowing us to clearly separate the responses for both organs and salinities. As gills come in contact with the environment first, we monitored gene the expression at intermediate time points (7, 14, and 21 days) for this organ in order to highlight clams responses to NM and salinity. Two genes (Se-GPx, MnSOD) had a salinity-dependent level of expression. HSP70, Se-GPx, and Trxr mRNAs presented significant changes in their expressions in the presence of NM. This study was completed using an integrated statistical approach. The exposed organisms differed more from control at field salinity than those exposed to hyper-saline conditions. At 15 psu, salinity pressure seems to cause the first molecular impact. At 1.5 psu, gene expression patterns allowed the effect of each NM to separate clearly. These results confirmed the usefulness of gene expression studies. Moreover, we highlighted the necessity to assess the environmental toxicity of the different forms of manufactured NM.

Using multi-integrated biomarker indexes approach to assess marine quality and health status of marine organism: a case study of Ruditapes philippinarum in Laizhou Bay, China

With the progress of technology and the deepening of understanding of biological monitoring, much more attention has been paid to the multiple evaluation of marine pollution monitoring. In view of this, our study aimed at establishing a multi-integrated biomarker indexes approach to evaluate marine condition systematically and comprehensively. In the current study, sampling was conducted in Laizhou Bay, China (S1, S2, and S3) in May, August, and October of 2015. And then, multi-integrated biomarker indexes approach was applied to assess marine PAHs pollution, select appropriate biomarkers, and evaluate marine environmental quality and health status of the clams of Ruditapes philippinarum. As the results showed, S2 was the most PAHs-polluted site while S1 was the least polluted site, and the levels of tPAHs in seawater and sediments ranged from 69.78 to 315.30 ng/L and 163.19 to 565.17 ng/g d.w., respectively. And all three sampling sites had different sources of PAHs. IBR represented DNA damage (F value), the expression of SOD, EROD activity, GST activity, and LPO could be served as biomarkers to monitor the PAHs pollution in Laizhou Bay. And MPI suggested the quality of all three sites: S1 was generally favorable, S2 was moderately polluted, and S3 was lightly polluted. BRI values showed that the order of health status of R. philippinarum was S1 > S3 > S2.

Extracellular degradation of tetrabromobisphenol A via biogenic reactive oxygen species by a marine Pseudoalteromonas sp

Tetrabromobisphenol A (TBBPA) has attracted considerable attention due to its ubiquitous presence in different environmental compartments worldwide. However, information on its aerobic biodegradability in coastal environments remains unknown. Here, the aerobic biodegradation of TBBPA using a Pseudoalteromonas species commonly found in the marine environment was investigated. We found that extracellular biogenic siderophore, superoxide anion radical (O₂^•-), hydrogen peroxide (H₂O₂), and hydroxyl radical (^•OH) were involved in TBBPA degradation. Upregulation of genes (nqrA and lodA) encoding Na⁺-translocating NADH-quinone oxidoreductase and l-lysine-ε-oxidase supported the extracellular O₂^•- and H₂O₂ production. The underlying mechanism of TBBPA biodegradation presumably involves both O₂^•- reduction and ^•OH-based advanced oxidation process (AOP). Furthermore, TBBPA intermediates of tribromobisphenol A, 4-isopropylene-2,6-dibromophenol, 4-(2-hydroxyisopropyl)-2,6-dibromophenol, 2,4,6-tribromophenol (TBP), 4-hydroxybenzoic acid, and 2-bromobenzoic acid were detected in the culture medium. Debromination and β-scission pathways of TBBPA biodegradation were proposed. Additionally, membrane integrity assays revealed that the increase of intracellular catalase (CAT) activity and the extracellular polymeric substances (EPS) might account for the alleviation of oxidative damage. These findings could deepen understanding of the biodegradation mechanism of TBBPA and other related organic pollutants in coastal and artificial bioremediation systems.

Integrated toxicity evaluation of metals in sediments of Jiaozhou Bay (China): Based on biomarkers responses in clam Ruditapes philippinarum exposed to sediment extracts

To evaluate the integrated toxicity of metals in sediments of Jiaozhou Bay, we exposed clam (Ruditapes philippinarum) to sediments extracts obtained using of sediment extraction with deionised water adjusted to pH 4 which simulated the weak acidity in the digestive juice of clams and tested the selected biomarkers responses in clams for exposure over 15 days. At the same time, the contents of metals in sediments were assessed with method of the mean sediment quality guideline quotient (SQG-Q). The integrated biomarker response version 2 (IBR_v2) was used to assess the integrated toxicity induced by metals in sediment extracts based on biomarkers response in clams: the results demonstrated that site S7 located in the mouth of Nanxin'an River show higher IBR_v2 values compared to the other sites. The IBR_v2 values exhibited the good consistency with SQG-Q values.

Toxicological responses on cytochrome P450 and metabolic transferases in liver of goldfish (Carassius auratus) exposed to lead and paraquat

As the producer of reactive oxygen species (ROS), both lead (Pb) and paraquat (PQ) can generate serious oxidative stress in target organs which result in irreversible toxic effects on organisms. They can disturb the normal catalytic activities of many enzymes by means of different toxicity mechanism. The changed responses of enzymes are frequently used as the biomarkers for indicating the relationship between toxicological effects and exposure levels. In this work, goldfish was exposed to a series of test groups containing lead and paraquat in the range of 0.05-10mg/L, respectively. Four hepatic enzyme activities, including 7-ethoxyresorufinO-deethylase (EROD), 7-benzyloxy-4-trifluoromethyl-coumarin-O-debenzyloxylase (BFCOD), glutathione S-transferase (GST) and UDP-glucuronosyltransferase (UGT) were determined after 1, 7, 14, 28 days exposure. The results showed that the activities of EROD and BFCOD in fish were significantly inhibited in response to paraquat at all exposure levels during the whole experiment. Similarly, the inhibitory effects of lead exposure on BFCOD activity were found in our study, while different responses of lead on EROD were observed. There were no significant differences on EROD activity under lower concentrations of lead (less than 0.1mg/L) before 14 days until an obvious increase was occurred for the 0.5mg/L lead treatment group at day 14. Furthermore, lead showed stronger inhibition on GST activity than paraquat when the concentrations of the two toxicants were more than 0.5mg/L. However, the similar dose and time-dependent manners of UGT activity were found under lead and paraquat exposure. Our results indicated that higher exposure levels and longer accumulations caused inhibitory effects on the four enzymes regardless of lead or paraquat stress. In addition, the responses of phase I enzymes were more sensitive than that of phase II enzymes and they may be served as the acceptable biomarkers for evaluating the toxicity effects of both lead and paraquat.