An integrated biomarker-based strategy for ecotoxicological evaluation of risk in environmental management

Non-destructive methods to assess pesticide exposure in free-living bats

Bat populations are dwindling worldwide due to anthropogenic activities like agriculture, however the role that pesticide exposure plays on these declines is unclear. To address these research gaps, we first need to develop reliable methods to detect and monitor exposure to environmental pollutants and its effects on free-living bats. The use of biomarkers is a sensitive and informative tool to study sublethal effects in wildlife, however it requires laboratory validation and integrative approaches to be applicable to free-living species. In this study, we propose a set of non-destructive biomarkers to evaluate pesticide exposure in free-ranging bats and validated their suitability with dose-exposure experiments in captivity. We selected three biomarkers that have been widely used in vertebrate ecotoxicology and that combined represent sensitive, specific, and ecologically relevant responses to pollutants: DNA damage, AChE activity, and leukocyte profiles. We used two insectivorous bat species as model species Eptesicus fuscus (laboratory) and Pteronotus mexicanus (field). We found that micronuclei frequency (genotoxicity) and AChE activity (exposure and neurotoxicity) were robust indicators of toxicant exposure. The validity of this set of endpoints was supported by their consistent performance in laboratory and field experiments as well as by the significant correlation among them. Leukocyte profile (systemic stress) results were not consistent between laboratory and field studies, suggesting further evaluation of its suitability is needed. Integrative approaches, like the one we used here, maximize the insights about toxicant effects by combining the information of single biomarkers into more meaningful inferences, which can be applied to environmental risk assessments in wildlife. Furthermore, the use of non-destructive, cost-effective biomarkers is imperative when assessing toxicant exposure and effects in vulnerable wildlife and it should be a priority in the field of wildlife toxicology.

Morphological and functional alterations in hemocytes of Mytilus galloprovincialis exposed in high-impact anthropogenic sites

The work aimed to study the induction of morphological alterations in M. galloprovincialis in the field and its suitability to be integrated into a sensitive, simple, and cost-effective cell-based multimarker approach for the detection of the stress status induced by pollution in coastal marine environments in view of ecotoxicological biomonitoring and assessment application. Cellular morphometric alterations was paralleled by the analysis of standardized biomarkers such as lysosomal membrane destabilization, and genotoxocity biomarkers such as micronuclei and binuclated cells frequencies were investigated. The study was carried out by means of a transplanting experiment in the field, using caged organisms from an initial population exposed in the field in two multi-impacted coastal sites of the central Mediterranean area, Bagnoli in the eastern Tyrrhenian Sea and Augusta-Melilli-Priolo in the western Ionian Sea. Capo Miseno (NA) for the Tyrrhenian area and Brucoli (ME) for the Ionian area were chosen as control sites. Hemocyte enlargement and filopodial elongation increased frequencies were observed in organisms exposed to the impacted sites. These morphometric alterations showed strong agreement with the lysosomal membrane destabilization and biomarkers of genotoxicity, suggesting their usefulness in detecting the pollutant-induced stress syndrome related to genotoxic damage.

Bioplastic leachates characterization and impacts on early larval stages and adult mussel cellular, biochemical and physiological responses

Bioplastics are promoted as safer alternatives to tackle the long-term persistence of conventional plastics. However, information on the potential release of additives and non-intentionally added substances (NIAS) in the surrounding environment is limited, and biological effects of the leachates have been little studied. Leachates produced from three bioplastics, i.e. compostable bags (CB), bio-polyethylene terephthalate bottles (bioPET) and polylactic acid cups (PLA), and a control polymeric material, i.e. rubber tire (TR), were examined. The chemical nature of bioplastic polyesters PET, PLA and poly (butylene adipate-co-terephthalate) (PBAT) in CB, was confirmed by analytical pyrolysis. Fragments were incubated in artificial sea water for 14 days at 20 °C in darkness and leachate contents examined by GC-MS and HPLC-MS/MS. Catalysts and stabilizers represented the majority of chemicals in TR, while NIAS (e.g. 1,6-dioxacyclododecane-7,12-dione) were the main components of CB. Bisphenol A occurred in all leachates at a concentration range 0.3-4.8 μg/L. Trace metals at concentrations higher than control water were found in all leachates, albeit more represented in leachates from CB and TR. A dose response to 11 dilutions of leachates (in the range 0.6-100%) was tested for biological effects on early embryo stages of Mytilus galloprovincialis. Embryotoxicity was observed in the whole range of tested concentrations, the magnitude of effect depending on the polymers. The highest concentrations caused reduction of egg fertilization (CB, bioPET, TR) and of larvae motility (CB, PLA, TR). TR leachates also provoked larvae mortality in the range 10-100%. Effects on adult mussel physiology were evaluated after a 7-day in vivo exposure to the different leachates at 0.6% concentration. Nine biomarkers concerning lysosomal functionality, neurotransmission, antioxidant and immune responses were assessed. All lysosomal parameters were affected, and serum lysozyme activity inhibited. Harmonized chemical and biological approaches are recommended to assess bioplastic safety and support production of sustainable bioplastics.

Assessment Toxicity of Soils from Areas with Mining Activity Through the Stability of the Lysosomal Membrane and Avoidance Behavior in the Earthworm Eisenia fetida

The aim of this study was to determine the effect of soils from areas with mining activity on the stability of the lysosomal membrane and avoidance behavior in the worm Eisenia fetida. Texture, organic material, conductivity and pH were determined in soils. The total concentrations of Cu, Zn, Pb, Ni, As and Hg were determined in tissues of E. fetida and in soils. Neutral red retention time (NRRT) was determined in hemocytes, and behavior with the avoidance test, in the earthworm. Cu (1563 ± 58 mg kg^-1) and Zn (135 ± 9 mg kg^-1) had the highest mean concentrations in the soils, while Hg (0.01 ± 0.001 mg kg^-1) had the lowest concentration in all the soils. The soil with the highest Cu concentration produced an avoidance of > 80%. Most of the soils produced a significant loss of the stability of the lysosomal membrane. The variables organic material and sand would facilitate habitat selection in E. fetida, In conclusion, the soils have chemical agents in bioavailable concentrations that provoke adverse cellular effects and evasion behavior. We propose the use of both response variables as early alerts in the evaluation of soils.

Ecological and human health risk assessment of potentially toxic element contamination in waters of a former asbestos mine (Canari, Mediterranean Sea): implications for management

Between 1948 and 1965, the Canari asbestos mine (Corsica, France) discharged 11 million tonnes of serpentinite rubble into the sea. This study, therefore, aims to assess the environmental and health risks associated with contamination of potentially toxic elements using bioindicators (seagrass and fish) in the areas bordering the former mine within the perimeter of the Cap Corse and Agriate Marine Natural Park. The results and multivariate statistical analyses of the potentially toxic elements, made it possible to identify a concentration gradient, a model of bioaccumulation, and the occurrence of different groups, thus reflecting a spatial variation of the contamination. These results indicate that the former asbestos mine can still be considered, 55 years after its closure, as a major source of Co, Cr, and Ni for marine ecosystems and still influences the quality of the coastal area today. Our study, therefore, indicates that the two most polluted sites (Albo and Negru) are the closest stations to the south of the old Canary asbestos mine. According to the Trace Elements Pollution Index (TEPI) values, 6 species were classified as having a high contamination level: Scorpaena notata (1.37), Scorpaena porcus (1.36), Sepia officinalis (1.27), Diplodus vulgaris (1.02), Spicara maena (0.95), and Mullus surmuletus (0.94). Regarding the potentially toxic elements measured in the edible tissues of fish, the concentrations were all below the regulatory thresholds and did not reveal any potential risk to human health (Cd, Cu, Fe, Pb, Se, Sn, Zn). This work provides new and useful information to improve the monitoring of the environmental quality of a region characterized by previous mining activity and to assess the potential risk to human health due to the consumption of fish. Beyond the purely scientific aspects, these results could serve as decision support at the regional level for the definition of long-term public policies.

Beach showers as sources of contamination for sunscreen pollution in marine protected areas and areas of intensive beach tourism in Hawaii, USA

In 2019, sands in nearby runoff streams from public beach showers were sampled on three islands in the State of Hawaii and tested for over 18 different petrochemical UV filters. Beach sands that are directly in the plume discharge of beach showers on three of the islands of Hawaii (Maui, Oahu, Hawai'i) were found to be contaminated with a wide array of petrochemical-based UV-filters that are found in sunscreens. Sands from beach showers across all three islands had a mean concentration of 5619 ng/g of oxybenzone with the highest concentration of 34,518 ng/g of oxybenzone at a beach shower in the Waikiki area of Honolulu. Octocrylene was detected at a majority of the beach shower locations, with a mean concentration of 296.3 ng/g across 13 sampling sites with the highest concentration of 1075 ng/g at the beach shower in Waikiki. Avobenzone, octinoxate, 4-methylbenzylidene camphor and benzophenone-2 were detected, as well as breakdown products of oxybenzone, including benzophenone-1, 2,2'-dihydroxy-4-methoxybenzophenone, and 4-hydroxybenzophenone. Dioxybenzone (DHMB) presented the highest concentration in water (75.4 ng/mL), whereas octocrylene was detected in all water samples. Some of these same target analytes were detected in water samples on coral reefs that are adjacent to the beach showers. Risk assessments for both sand and water samples at a majority of the sampling sites had a Risk Quotient > 1, indicating that these chemicals could pose a serious threat to beach zones and coral reef habitats. There are almost a dozen mitigation options that could be employed to quickly reduce contaminant loads associated with discharges from these beach showers, like those currently being employed (post-study sampling and analysis) in the State of Hawaii, including banning the use of sunscreens using petrochemical-based UV filters or educating tourists before they arrive on the beach.

Oxidative, biochemical and histopathological alterations in fishes from pesticide contaminated river Ganga, India

The river Ganga basin accommodates large scale of agricultural activities, where large quantities of pesticides are applied. To assess the biological impact of pesticide residues that are continuously entering in the water body, biomarkers are common approach in bio-monitoring study as early warning signals to pollutants. In the present study qualitative and quantitative analyses of gill and liver histopathological and the biochemical parameters were determined in Rita rita and Cyprinus carpio. The difference in the histopathology and oxidative stress responses emphasize the response of selected fishes to the presence of contaminants in the water. Sloughing of lamellar epithelium and their disruption, dilated vessels, lamellar fusion, smooth muscle hypertrophy in the gill and necrosis, Vacuolation in hepatocytes, inflammation and distorted arterial walls were seen in the liver. The biochemical parameters were the main contributors to discriminate the changes in the fish physiology. In conclusion, the gill and liver histopathological responses, although not reflecting specific contaminants, but can be used as biomarkers of environmental contamination.

Oxybenzone contamination from sunscreen pollution and its ecological threat to Hanauma Bay, Oahu, Hawaii, U.S.A

Hanauma Bay is a 101-acre bay created by the partial collapse of a volcanic cone and once supported a vibrant coral reef system. It is the most popular swimming area in the Hawaiian Islands and has been reported to have averaged between 2.8 and 3.5 million visitors a year between the 1980s and the 2010s, with visitors averaging between 3000-4000 a day and peaking around 10,000-13,000 per day. Concentrations of oxybenzone and other common UV filters were measured in subsurface water samples and in sands from the beach-shower areas in Hanauma Bay. Results demonstrate that beach showers also can be a source of sunscreen environmental contamination. Hydrodynamic modeling indicates that oxybenzone contamination within Hanauma Bay's waters could be retained between 14 and 50 h from a single release event period. Focusing on only oxybenzone, two different Hazard and Risk Assessment analyses were conducted to determine the danger of oxybenzone to Hanauma Bay's coral reef system. Results indicate that oxybenzone contamination poses a significant threat to the wildlife of Hanauma Bay. To recover Hanauma Bay's natural resources to a healthy condition and to satisfactorily conserve its coral reef and sea grass habitats, effective tourism management policies need to be implemented that mitigate the threat of sunscreen pollution.

Cu, Ni, and Zn effects on basic physiological and stress parameters of Raphidocelis subcapitata algae

The submitted work observed Cu, Ni, and Zn effects on selected physiological and stress parameters of the alga Raphidocelis (Pseudokirchneriella) subcapitata. In 96-h experiments, EC50 values for algal specific growth rates (SGR) inhibition in Cu, Ni, and Zn presence were estimated as 0.15, 0.50, and 0.20 mg l^-1. In addition to growth inhibition, the effect of metals at various concentrations on algal SGR was also monitored. While these experiments confirmed approximately the same toxicity of Zn and Cu on SGR, Ni toxicity on this parameter was observed as the lowest. In terms of the effect of metals on the level of selected photosynthetic pigments, chlorophyll a, chlorophyll b, and carotenoids, the following inhibition orders can be established: Zn > Cu > Ni, Ni > Cu > Zn, and Ni > Cu ≥ Zn, respectively. As a novelty of our research, we included monitoring and evaluation of the intensity of stress, which was the response of algal cells to the presence of Cu, Ni, and Zn, and its correlation with respect to production factors and metal accumulation in algal cells. As stress factors, thiol (-SH) group and TBARS (thiobarbituric acid reactive substances) as significant indicators of lipid level peroxidation were determined. The content of -SH groups depended on the concentration of metal, and its level was the most stimulated by Zn, less by Cu and Ni. The TBARS content was 2 to 5 times higher in Cu than in Zn or Ni presence. In the presence of Zn and Ni, TBARS content reached approximately the same levels. For this parameter, the following rank order can be arranged: Cu >> Ni ≥ Zn. While Cu and Ni accumulation in R. subcapitata was confirmed, Zn accumulation was not determined or was below the detectable limit. Regression analyses revealed significant positive correlation between Cu accumulation and TBARS while carotenoids as possible antioxidants confirmed with TBARS mostly negative correlations.

Organochlorine Pesticide Ban Facilitated Reproductive Recovery of Chinese Striped Hamsters

Organochlorine pesticides (OCPs) have been used worldwide on an enormous scale over the last century but are banned globally due to environmental persistence and ecotoxicity in recent decades. The long-term effects of OCP ban for agricultural use in China since 1983 on the reproductive health of small terrestrial mammals have never been evaluated in the field. We examined the residue dynamics of OCPs and the reproductive performance of Chinese striped hamsters (Cricetulus barabensis) in North China Plain during 1983-2010 and concluded that the exposure levels of OCPs in hamsters drastically decreased from 2900 ± 740 to 25.2 ± 6.88 ng/g with an average half-life of 5.08 yrs, coinciding with the observed reproductive recovery of hamsters. The population-based reproductive performance of hamsters was significantly and negatively associated with OCP exposure levels after adjusting the contributions from climate and population density factors, indicating that the ban of OCPs has facilitated the reproductive recovery of hamsters by up to 81% contribution. Our findings suggest that the OCP ban is effective to restore reproduction of small terrestrial mammals. Integration of population biology and environmental science is essential to assess the impacts of persistent organic pollutants on ecological safety and biodiversity loss under accelerated global change.

Marine health of the Arabian Gulf: Drivers of pollution and assessment approaches focusing on desalination activities

The Arabian Gulf is one of the most adversely affected marine environments worldwide, which results from combined pollution drivers including climate change, oil and gas activities, and coastal anthropogenic disturbances. Desalination activities are one of the major marine pollution drivers regionally and internationally. Arabian Gulf countries represent a hotspot of desalination activities as they are responsible for nearly 50% of the global desalination capacity. Building desalination plants, up-taking seawater, and discharging untreated brine back into the sea adversely affects the biodiversity of the marine ecosystems. The present review attempted to reveal the potential negative effects of desalination plants on the Gulf's marine environments. We emphasised different conventional and innovative assessment tools used to assess the health of marine environments and evaluate the damage exerted by desalination activity in the Gulf. Finally, we suggested effective management approaches to tackle the issue including the significance of national regulations and regional cooperation.

Antagonistic cytoprotective effects of C60 fullerene nanoparticles in simultaneous exposure to benzo[a]pyrene in a molluscan animal model

The hypothesis that C₆₀ fullerene nanoparticles (C₆₀) exert an antagonistic interactive effect on the toxicity of benzo[a]pyrene (BaP) has been supported by this investigation. Mussels were exposed to BaP (5, 50 & 100μg/L) and C₆₀ (C₆₀-1mg/L) separately and in combination. Both BaP and C₆₀ were shown to co-localize in the secondary lysosomes of the hepatopancreatic digestive cells in the digestive gland where they reduced lysosomal membrane stability (LMS) or increased membrane permeability, while BaP also induced increased lysosomal lipid and lipofuscin, indicative of oxidative cell injury and autophagic dysfunction. Combinations of BaP and C₆₀ showed antagonistic effects for lysosomal stability, mTORC1 (mechanistic target of rapamycin complex 1) inhibition and intralysosomal lipid (5 & 50μg/L BaP). The biomarker data (i.e., LMS, lysosomal lipidosis and lipofuscin accumulation; lysosomal/cell volume and dephosphorylation of mTORC1) were further analysed using multivariate statistics. Principal component and cluster analysis clearly indicated that BaP on its own was more injurious than in combination with C₆₀. Use of a network model that integrated the biomarker data for the cell pathophysiological processes, indicated that there were significant antagonistic interactions in network complexity (% connectance) at all BaP concentrations for the combined treatments. Loss of lysosomal membrane stability probably causes the release of intralysosomal iron and hydrolases into the cytosol, where iron can generate harmful reactive oxygen species (ROS). It was inferred that this adverse oxidative reaction induced by BaP was ameliorated in the combination treatments by the ROS scavenging property of intralysosomal C₆₀, thus limiting the injury to the lysosomal membrane; and reducing the oxidative damage in the cytosol and to the nuclear DNA. The ROS scavenging by C₆₀, in combination with enhanced autophagic turnover of damaged cell constituents, appeared to have a cytoprotective effect against the toxic reaction to BaP in the combined treatments.

Identification and evaluation of antioxidant and reference genes for quantitative real-time PCR in blood of Caiman latirostris

The quantitative real-time polymerase chain reaction (qPCR) has been one of the most promising approaches to perform rapid and accurate quantification of DNA in various biological systems. The aim of this study was to standardized the qPCR technique for the analysis of important genes involved in the main routes of antioxidant defense against reactive oxygen species (catalase: cat and superoxide dismutase: sod) and evaluate the stability of different reference genes in blood of Caiman latirostris hatchlings. The stability of the reference genes, β-actin, glyceraldehyde 3-phosphate dehydrogenase (gapdh) and ribosomal protein L8 (rpl8) was determined using the comparative ΔCt, NormFinder, geNorm, BestKeeper and RefFinder. Then, cat and sod genes were normalized with each reference gene and their mRNA abundances were determined through the qPCR. Stability of genes was ranked through the different methods in the following order: β-actin, rpl8 and gapdh , under normal physiological conditions. The results reveal that cat and sod genes present a similar relative mRNA abundance with β-actin and rpl8. This is the first report of the analysis of antioxidant mRNA as potential biomarkers of oxidative stress in blood for all crocodilians species. Besides, we determined the stability of different reference genes that can be used for normalization of mRNA abundance patterns in blood of C. latirostris, without the need to sacrifice the animals.

Metabolic status of the coral Mussismilia harttii in field conditions and the effects of copper exposure in vitro

It is widely known that metals can alter enzyme functioning, however, little is known about the mechanisms of metal toxicity in energy metabolism enzymes of corals. Thus, the present study had two objectives: firstly, we evaluated the activity of eight metabolic enzymes of the coral Mussismilia harttii to clarify metabolic functioning under field conditions. After that, we investigated the in vitro effect of copper (Cu) exposure in the activity of an enzyme representative of each metabolism stage. We evaluated enzymes involved in glycolysis (hexokinase, HK; phosphofructokinase, PFK; pyruvate kinase, PK and lactate dehydrogenase, LDH), Krebs cycle (citrate synthase, CS and isocitrate dehydrogenase, IDH), electron transport chain (electron transport system activity, ETS) and pentose phosphate pathway (glucose-6-phosphate dehydrogenase, G6PDH). The in vitro tests were performed through contamination of the reaction medium using Cu concentrations of 0, 1.4, 3.7 and 14.2 μg L^-1. The results showed that M. harttii has elevated activity of HK, PK and CS in field conditions compared to the activity of other energy metabolism enzymes evaluated. Moreover, lower activities of LDH and ETS in exposed samples were observed. In conclusion, in field conditions this species has elevated aerobic metabolism and glucose may be an important energetic fuel. Also, exposure to Cu in vitro caused inhibition of LDH and ETS by direct binding.

Nondestructive biomarkers in giant toad (Rhinella marina) to assess the effect of complex mixture of pollutants in Coatzacoalcos River, Mexico

In this study, we evaluated the usefulness of nondestructive biomarkers approach in giant toads (Rhinella marina). We obtained blood samples and the residual condition index of toads from rural and industrial zones from Coatzacoalcos River, Mexico (COA). In the blood samples, we determined the activity of enzymes, lipid peroxidation, and the presence of cell death (apoptosis). We found that the activity of the enzyme delta-aminolevulinic dehydratase was lower. Still, the glutathione s-transferase activity and the percentage of apoptosis in erythrocytes were higher in the toads of COA than laboratory toads. Meanwhile, some biomarkers in toads showed differences when compared between Industrial and Rural zones. These results and correlations between biomarkers showed how the response changed in the toads living near the industrial zones. We demonstrate that a nondestructive biomarkers approach can be useful in environmental studies with anuran amphibians.

Cellular and molecular complementary immune stress markers for the model species Dreissena polymorpha

This study aimed to combine cellular and molecular analyses for better detail the effects of various stresses on a sentinel species of freshwater invertebrate. For this purpose, the hemocytes of the zebra mussel, Dreissena polymorpha, were exposed to different stresses at two different intensities, high or low: chemical (cadmium and ionomycin), physical (ultraviolet B), or biological ones (Cryptosporidium parvum and Toxoplasma gondii). After exposure, flow cytometry and droplet digital PCR analyses were performed on the same pools of hemocytes. Several responses related to necrosis, apoptosis, phagocytosis, production of nitric oxide and expression level of several genes related to the antioxidant, detoxification and immune systems were evaluated. Results showed that hemocyte integrity was compromised by both chemical and physical stress, and cellular markers of phagocytosis reacted to ionomycin and protozoa. While cadmium induced oxidative stress and necrosis, ionomycin tends to modulate the immune response of hemocytes. Although both biological stresses led to a similar immune response, C. parvum oocysts induced more effects than T. gondii, notably through the expression of effector caspases gene and an increase in hemocyte necrosis. This suggests different management of the two protozoa by the cell. This work provides new knowledge of biomarkers in the zebra mussel, at both cellular and molecular levels, and contributes to elucidate the mechanisms of action of different kinds of stress in this species.

Effects of abamectin-based and difenoconazole-based formulations and their mixtures in Daphnia magna: a multiple endpoint approach

This study evaluated the toxicity of pesticide formulations Kraft® 36 EC (active ingredient-a.i. abamectin) and Score® 250 EC (a.i. difenoconazole), and their mixtures in Daphnia magna at different biological levels of organization. Survival, reproduction and biochemical markers (cholinesterase (ChE), catalase (CAT) and lipid peroxidation (LPO)) were some of the endpoints evaluated. Total proteins and lipids were also studied together with energy consumption (Ec). D. magna neonates were exposed for 96 h to Kraft (2, 4, and 6 ng a.i./L) and Score (12.5, 25, and 50 µg a.i./L) for the biochemical experiments, and for 15 days to abamectin (1-5 ng a.i./L) and to difenoconazole (3.12-50 µg a.i./L) to assess possible changes in reproduction. Exposures of organisms to both single compounds did not cause effects to antioxidant and detoxifying enzymes, except for LPO occurring at the highest concentration of difenoconazole tested. For ChE and CAT there was enzymatic induction in mixture treatments organisms, occurring at minor pesticides concentrations for CAT and at the two highest concentrations for ChE. There were no significant differences for total protein in D. magna but lipids showed an increase at the highest concentrations of pesticide mixture combinations. There was a significant increase of Ec in individuals of all treatments tested. In the chronic test, increased fecundity occurred for D. magna under difenoconazole exposures and mixtures. This study demonstrated that mixtures of these pesticides caused greater toxicity to D. magna than when tested individually, except for Ec. Therefore, effects of mixtures are very hard to predict only based on information from single compounds, which most possibly is the result of biological complexity and redundancy in response pathways, which need further experimentation to become better known.

Evaluation of interactive effects of phosphorus-32 and copper on marine and freshwater bivalve mollusks

PURPOSE

Contaminants seldom occur in isolation in the aquatic environment. While pollution of coastal and inland water bodies has received considerable attention to date, there is limited information on potential interactive effects between radionuclides and metals. Whether by accidental or controlled release, such contaminants co-exist in aquatic ecosystems and can pose an enhanced threat to biota. Using a range of biological responses, the study aimed to evaluate relative interactive effects on representative freshwater and marine bivalve species.

METHODS

An integrated, multi-biomarker approach was adopted to investigate response to copper (Cu, 18 μg L^-1), a known environmentally relevant genotoxic metal and differing concentrations of phosphorus-32 (³²P; 0.1 and 1 mGy d^-1), alone and in combination in marine (Mytilus galloprovincialis) and freshwater (Dreissena polymorpha) mussels. Genetic and molecular biomarkers were determined post-exposure and included DNA damage (as measured by the comet assay), micronuclei (MN) formation, γ-H2AX foci induction and the expression of key stress-related genes (i.e. hsp70/90, sod, cat, gst).

RESULTS

Overall, using a tissue-specific (i.e. gill and digestive gland) approach, genotoxic response was reflective of exposures where Cu had a slight additive effect on ³²P-induced damage across the species (but not all), cell types and dose rates. Multivariate analysis found significant correlations between comet and γ-H2AX assays, across both the tissues. Transcriptional expression of selected genes were generally unaltered in response to contaminant exposures, independent of species or tissues.

CONCLUSIONS

Our study is the first to explore the interactive effects of ionizing radiation (IR) and Cu on two bivalve species representing two ecological habitats. The complexity of IR-metal interactions demonstrate that extrapolation of findings obtained from single stressor studies into field conditions could be misrepresentative of real-world environments. In turn, environmental protective strategies deemed suitable in protecting biota from a single, isolated stressor may not be wholly adequate.

Assessment of copper, chromium, and lead toxicity in fish (Ctenopharyngodon idella Valenciennes, 1844) through hematological biomarkers

Hematological variances were seen in Ctenopharyngodon idella when exposed to (LC50 and LC85) copper, chromium, and lead concentration groups. The metal-exposed blood samples after collection were analyzed for comparative analysis of hematological alterations in the reference and treated groups at the different exposure hours. A significant reduction (p < 0.05) in hemoglobin, RBC, hematocrit, total leucocyte, and lymphocyte counts was observed with the increase in metal concentrations, whereas a significant incline (p < 0.05) in granulocyte and monocyte counts was observed with the administered doses of selected toxic metals as compared with the values obtained from the reference group. More pronounced changes in hematological indices both for the red and white blood cells were noticed at the highest dose of LC85-administered metal groups. The induced hematological changes were independent of the exposed duration pattern. The present investigation has significantly contributed in knowledge assessment of metal toxicity based on inclusive evaluation of dose-response relationships.

Lysosomes, Autophagy, and Hormesis in Cell Physiology, Pathology, and Age-Related Disease

Autophagy has been strongly linked with hormesis, however, it is only relatively recently that the mechanistic basis underlying this association has begun to emerge. Lysosomal autophagy is a group of processes that degrade proteins, protein aggregates, membranes, organelles, segregated regions of cytoplasm, and even parts of the nucleus in eukaryotic cells. These degradative processes are evolutionarily very ancient and provide a survival capability for cells that are stressed or injured. Autophagy and autophagic dysfunction have been linked with many aspects of cell physiology and pathology in disease processes; and there is now intense interest in identifying various therapeutic strategies involving its regulation. The main regulatory pathway for augmented autophagy is the mechanistic target of rapamycin (mTOR) cell signaling, although other pathways can be involved, such as 5'-adenosine monophosphate-activated protein kinase. Mechanistic target of rapamycin is a key player in the many highly interconnected intracellular signaling pathways and is responsible for the control of cell growth among other processes. Inhibition of mTOR (specifically dephosphorylation of mTOR complex 1) triggers augmented autophagy and the search is on the find inhibitors that can induce hormetic responses that may be suitable for treating many diseases, including many cancers, type 2 diabetes, and age-related neurodegenerative conditions.

PVC Does Not Influence Cadmium Uptake or Effects in the Mussel (Mytilus edulis)

Microplastics have become a global concern in recent years. In this study, we studied (i) whether the presence of polyvinyl chloride (PVC) microparticles may affect cadmium (Cd) uptake in mussel (Mytilus edulis); and (ii) the biological effects of PVC microparticles exposure alone or in combination with Cd. Significant Cd uptake in digestive gland was observed following Cd exposure. However, PVC did not significantly increase Cd uptake compared with Cd alone treatment. In terms of biological impacts, significantly lower neutral red retention (NRR) time and elevated expression of Metallothionein isoform 20-IV (MT-20) were observed in mussels exposed to Cd alone, or combined with microplastics, yet there was no significant difference between them. catalase (CAT) expression only showed a significant increase in mussels exposed to Cd alone. This work provides an insight into the relationship on resulting biological impacts between these two contaminants.

The Toxicity of Nanoparticles to Organisms in Freshwater

Nanotechnology is a rapidly growing industry yielding many benefits to society. However, aquatic environments are at risk as increasing amounts of nanoparticles (NPs) are contaminating waterbodies causing adverse effects on aquatic organisms. In this review, the impacts of environmental exposure to NPs, the influence of the physicochemical characteristics of NPs and the surrounding environment on toxicity and mechanisms of toxicity together with NP bioaccumulation and trophic transfer are assessed with a focus on their impacts on bacteria, algae and daphnids. We identify several gaps which need urgent attention in order to make sound decisions to protect the environment. These include uncertainty in both estimated and measured environmental concentrations of NPs for reliable risk assessment and for regulating the NP industry. In addition toxicity tests and risk assessment methodologies specific to NPs are still at the research and development stage. Also conflicting and inconsistent results on physicochemical characteristics and the fate and transport of NPs in the environment suggest the need for further research. Finally, improved understanding of the mechanisms of NP toxicity is crucial in risk assessment of NPs, since conventional toxicity tests may not reflect the risks associated with NPs. Behavioural effects may be more sensitive and would be efficient in certain situations compared with conventional toxicity tests due to low NP concentrations in field conditions. However, the development of such tests is still lacking, and further research is recommended.

Presence of pharmaceutical compounds, levels of biochemical biomarkers in seafood tissues and risk assessment for human health: Results from a case study in North-Western Spain

This study assessed the presence of 27 pharmaceutically active compounds belonging to common therapeutic groups (cardiovascular, antiashmatic, psychoactive, diuretic, analgesic/anti-inflammatory, and antibiotic drugs) in the tissues of representative seafood species of bivalves, cephalopods, arthropods, and fish of high economic importance and consumption rates in North-Western Spain. Four pharmaceutical compounds, out of the 27 analyzed, were detected in the collected samples. The benzodiazepine citalopram was detected in the tissues of common octopus (14.1 ng g^-1 dry weight) and pod razor (9.4 ng g^-1 dw). The anxiolytic venlafaxine was detected in the tissues of common cockle (2.9 ng g^-1 dw). The veterinary antiparasitic ronidazole was found in pod razor (2.3 ng g^-1 dw) and, finally, the psychoactive compound alprazolam was also measured in common octopus (0.3 ng g^-1 dw). Hazard quotients were calculated to assess the hazard posed by the consumption of the sampled seafoods. Octopus and pod razor tissues containing citalopram and alprazolam exceeded our chosen hazard limits (HQ > 0.1) for toddlers who are high consumers of seafood (HQ values between 0.18 and 0.27). A battery of biochemical biomarkers of effects (acetylcholinesterase, glutathione S-transferase; catalase, glutathione peroxidase and glutathione reductase enzymes activities and reduced/oxidized glutathione and malondialdehyde levels) was applied to samples of the study species with the aim of characterizing their basal levels and evaluating their suitability as a tool in the monitoring chronic exposure to environmental contaminants such as those analyzed in this study. According to the measured biomarkers, pod razor and cockles have the potential to be good bioindicator species, based on the observed among-site differences detected on acetylcholinesterase, glutathione S-transferase, catalase, glutathione peroxidase activities; reduced/oxidized glutathione and malondialdehyde levels.

Effects of Five Substances with Different Modes of Action on Cathepsin H, C and L Activities in Zebrafish Embryos

Cathepsins have been proposed as biomarkers of chemical exposure in the zebrafish embryo model but it is unclear whether they can also be used to detect sublethal stress. The present study evaluates three cathepsin types as candidate biomarkers in zebrafish embryos. In addition to other functions, cathepsins are also involved in yolk lysosomal processes for the internal nutrition of embryos of oviparous animals until external feeding starts. The baseline enzyme activity of cathepsin types H, C and L during the embryonic development of zebrafish in the first 96 h post fertilisation was studied. Secondly, the effect of leupeptin, a known cathepsin inhibitor, and four embryotoxic xenobiotic compounds with different modes of action (phenanthrene-baseline toxicity; rotenone-an inhibitor of electron transport chain in mitochondria; DNOC (Dinitro-ortho-cresol)-an inhibitor of ATP synthesis; and tebuconazole-a sterol biosynthesis inhibitor) on in vivo cathepsin H, C and L total activities have been tested. The positive control leupeptin showed effects on cathepsin L at a 20-fold lower concentration compared to the respective LC50 (0.4 mM) of the zebrafish embryo assay (FET). The observed effects on the enzyme activity of the four other xenobiotics were not or just slightly more sensitive (factor of 1.5 to 3), but the differences did not reach statistical significance. Results of this study indicate that the analysed cathepsins are not susceptible to toxins other than the known peptide-like inhibitors. However, specific cathepsin inhibitors might be identified using the zebrafish embryo.

Comparative study of esterase activities in different tissues of marine fish species Trachurus trachurus, Merluccius merluccius and Trisopterus luscus

Pesticides are one of the most frequently anthropogenic xenobiotics detected in water. Among these, the organophosphorus pesticides (OPs) are very widely used in agriculture due to their broad spectrum of activity and their low price, but they also have high potent effects as neurotoxic compounds in non-target organisms. The aim of this study was to evaluate biomarkers acetylcholinesterase (AChE), butyrylcholinesterase (BChE), propionylcholinesterase (PChE) and carboxylesterase (CbE) in the representative Atlantic fish species Trachurus trachurus, Merluccius merluccius and Trisopterus luscus from "Rías Gallegas", a traditional Spanish fishing area. These esterase activities were evaluated in the brain, muscle and liver to determine the most adequate tissue to measure such enzymatic activities. The sensitivity of AChE and CbE activities from different tissues the widely used organophosphorus insecticide chlorpyrifos (CP), and its toxic metabolite (CP-oxon) was also tested. AChE activity was predominant in all tissues of the analysed species (particularly in brain constituting from 78.33%, 89.83% and 88.43% of total ChEs in Trachurus trachurus, Merluccius merluccius and Trisopterus luscus, respectively). Under in vitro exposure, esterases were shown to be highly sensitive to CP and especially to CP-oxon. Moreover, a similar effect observed on AChE and CbE activities could suggest that CbE activity might contribute efficiently against the toxic effects of CP, especially in muscle and the liver. The presence of BChE, PChE and upper CbE activities in muscle and the liver and their OP-sensibilities can be used to study their function in the pesticide biochemical detoxification pathways with a prominent role as a safeguarding mechanism against pesticide toxicity.

Endophytic bacteria of desert cactus (Euphorbia trigonas Mill) confer drought tolerance and induce growth promotion in tomato (Solanum lycopersicum L.)

Endophytic bacteria isolated from cactus were characterized and assessed for their capability to induce drought tolerance and growth promotion in tomato. A total of 191-bacteria representing 13-genera and 18-species were isolated from wild cactus, Euphorbia trigonas. Bacillus (58), Lysinibacillus (36), Enterobacter (29), Stenotrophomonas (18), Lelliottia (12) and Pseudomonas (12) were the most represented genera. 16S rDNA sequence (>1400-bp) comparison placed the bacterial isolates with Bacillus xiamenensis; Bacillus megaterium; Bacillus cereus; Bacillus amyloliquefaciens; Bacillus velezensis; Brevibacillus brevis; Lysinibacillus fusiformis; Enterobacter cloacae; Lelliottia nimipressuralis; Proteus penneri; Sphingobacterium multivorum; Klebsiella pneumoniae; Pseudomonas putida; Pseudomonas aeruginosa; Stenotrophomonas maltophilia; Citrobacter freundii; Chryseobacterium indologenes and Paracoccus sp. Bacillus xiamenensis was identified for the first time as plant endophyte. Upon bacterization, the endophytes triggered germination and growth promotion in tomato as indicated by 118 % and 52 % more root-biomass under drought-free and drought-induced conditions, respectively. Bacillus amyloliquefaciens CBa_RA37 and B. megaterium RR10 displayed broad spectrum endophytism in tomato. Bacterization of tomato with cactus endophyte showed altered oxidative status, stomatal and photosystem II functioning, internal leaf temperature and relative water content suggestive of physiological de-stressing from moisture stress. Activity of oxidative stress enzymes such as guaiacol peroxidase and catalase was also indicative of endophyte assisted de-stressing of tomato. Re-irrigation on 20-days of drought infliction showed 86.9% recovery of B. amyloliquefaciens CBa_RA37 primed tomato when non-primed plantlets succumbed. The cactus endophytic bacterial strain B. amyloliquefaciens CBa_RA37 showed promise for low-cost, efficient and environmentally friendly bio-inoculant technology to mitigate drought in arid zones of Asian and African continents.

Neurotoxicity of organophosphate pesticides could reduce the ability of fish to escape predation under low doses of exposure

Biomarkers are frequently used in ecotoxicology as they allow to study toxicant effects happening at low concentrations of exposure. However, most sublethal studies only evaluate cellular biomarkers which lack evident ecological relevance. We used a multibiomarker approach to estimate the toxic effects of ethoprophos, an organophosphate insecticide commonly used in banana plantations, on the tropical fish Astyanax aeneus (Characidae). We measured biomarkers at sub-individual (cellular) and individual (metabolism, behavior) levels and examined relationships among these responses. A sublethal exposure to ethoprophos caused a significant (54%) reduction of brain Cholinesterase (ChE) activity, reflecting the pesticide's high neurotoxicity. However, other biomarkers like oxidative stress, biotransformation reactions, and resting metabolic rate were not affected. Exposure to ethoprophos modified antipredator behaviors such as escape response and detection avoidance (light/dark preference): exposed fish escaped slower from a simulated attack and preferred brighter areas in a novel tank. The relationship between ChE activity and reaction time suggests that pesticide-induced ChE inhibition reduces escape ability in fish. Our results provide evidence that impacts of organophosphate pesticides on fish ecological fitness can occur even with short exposures at very low concentrations.

Biochemical and molecular responses of cyprinids in two Mediterranean lacustrine ecosystems: Opportunities for ecological assessment and biomonitoring

Lacustrine ecosystems have been altered by accelerating pollution, excessive nutrient and organic load, water abstraction, and are susceptible to climate change. Hence, suggesting sensitive and reliable biomarkers for early assessments of their status is of urgent need. In this study, two freshwater commercial fish species, Cyprinus carpio (carp) and Carassius gibelio (prussian carp) from two lakes (i.e. Koronia and Volvi, Northern Greece) with different anthropogenic pressures were used and a battery of biochemical and molecular biomarkers related to stress response were analyzed in fish gills and liver. In parallel, water physicochemical parameters (T, DO, pH, conductivity, salinity), BOD₅ and nutrient (N-NO₃, N-NO₂, N-NH₄, P-PO₄) concentrations were measured. Results showed that Lake Koronia had higher conductivity and salinity values and N-NO₂ concentrations. Levels of Heat Shock Response (HSR), MAPK phosphorylation, protein carbonylation, lipid peroxidation products, Bax/Bcl-2 ratio, ubiquitination and caspases were increased in gills and liver of both fish species sampled from Lake Koronia in relation to those of Lake Volvi. Likewise, liver lipid content was increased in both fish species sampled from Lake Koronia compared to those sampled from Lake Volvi. The results indicate and reflect the higher environmental degradation that prevails in Lake Koronia ecosystem in comparison to that of Lake Volvi. The fish species studied showed different susceptibility depending on the biomarkers examined. In addition, our results from both examined species provide insight into the mechanisms involved in acclimatization to stressful environments and support the role of the studied biomarkers as sensitive and reliable tools for ecological assessments of lake ecosystems in biomonitoring studies.

Evaluation of 4-nonylphenol and bisphenol A toxicity using multiple molecular biomarkers in the water flea Daphnia magna

Alkylphenols are well-known endocrine disruptors and may cause developmental and reproductive disorders in aquatic organisms. Daphnia magna is commonly used in ecotoxicological studies as a promising model species to investigate the effects of endocrine distruptors. In the present study, transcriptional modulation of eleven potential molecular indicators related to detoxification, antioxidant, development, and cellular stress was analyzed in D. magna exposed to different concentrations of bisphenol A (BPA) and 4-nonylphenol (4-NP) for 24 h and 48 h, using real-time qPCR. A hierarchical clustering analysis was applied to investigate relations among molecular markers depending on the compound, exposure duration, and concentration. Our findings suggested that GSH-related systems and stress proteins may be involved in cellular defense against BPA and 4-NP-mediated toxicity with different modes of action. Furthermore, these compounds may interrupt molting and reproduction in daphnids. In particular, D. magna GSH-related genes seem to be strongly affected by 4-NP exposure, indicating their potential as molecular biomarkers.

Microalgal whole-cell biomarkers as sensitive tools for fast toxicity and pollution monitoring of urban wet weather discharges

Urban wet weather discharge (UWWD) management is an important issue. UWWD often represents a significant source of pollution in all aquatic bodies. The occurrence of this pollution is difficult to predict due to the variability of storm events and the unknown contents of urban watershed leached out by rain. Previous studies have tried to demonstrate the ecotoxic impact of UWWD. However, most of them merely highlight the limitations of classic monospecific bioassays, given the high dilution of micropollutants or the presence of nutrients masking toxic effects. Overcoming this problem is therefore of great interest. In this study, we demonstrated the utility of a battery of biomarkers (e.g. membrane permeability, chlorophyll fluorescence, esterase and alkaline phosphatase activities) on the microalgae Chlorella vulgaris to detect the toxic effects of 7 UWWD samples after short exposures (2 and 24 h). These biomarkers are linked to microalgal life traits. Complementarily, monospecific bioassays were carried on Pseudokirchneriella subcapitata, Chlorella vulgaris, Daphnia magna and Heterocypris incongruens to compare their sensitivity to the UWWD samples. No toxic effect was detected in any of the bioassays. Yet, algal biomarkers indicated a disturbance in microalgae physiology, and particularly a perturbation of chlorophyll fluorescence, which was observed in all of the samples tested. While algal membrane permeability was affected by only one UWWD, these two enzymatic activities were stimulated or inhibited depending on the sample. Finally, this study demonstrates the sensitivity of algal biomarkers and the need to develop new, fruitful approaches to characterizing UWWD toxicity.

What is the relationship between the bioaccumulation of chemical contaminants in the variegated scallop Mimachlamys varia and its health status? A study carried out on the French Atlantic coast using the Path ComDim model

Increasing activity along the French Atlantic coast has led to chronic pollution with, in particular, mixtures of contaminants such as hydrocarbons, phytosanitary products, PCBs and heavy metals. Based on previous research, pollution biomarkers were used in this study as they can indicate health status when monitoring the impact of pollutants on coastal species such as the marine bivalve Mimachlamys varia. Mollusc bivalves were sampled in March 2016, in open and semi-open areas (a harbour zone), from thirteen sites which differed in terms of their level of pollution, and were located along the Atlantic coast from Brittany down to the Nouvelle-Aquitaine region. First, analyses of heavy metals and organic contaminants (e.g. pesticides, polycyclic aromatic hydrocarbons, polychlorobiphenyl) in the digestive gland of bivalves were performed. Second, biochemical assays were used to study defence biomarkers: oxidative stress with Superoxide Dismutase (SOD), detoxification of organic compounds with Glutathione-S Transferase (GST), lipid peroxidation with Malondialdehyde (MDA), and immune processes with Laccase. In addition to the biochemical assays, a genetic approach was used to measure genetic diversity (haplotype and nucleotide diversity) at each site. Biomarker assays and genetic diversity were correlated with the chemical contaminants in bivalves using the Path-ComDim statistical model. Our results showed specific correlations between biochemical assays in the digestive glands with heavy metal contaminants, and between genetic diversity and organic pollution. Blocks of responses were analysed for correlations in order to develop standardized tools and guidelines that could improve our understanding of the short-term and long-term impact of contaminants on physiological parameters.

Impact of multiple stressors on biomarker responses in sympatric dreissenid populations

Dreissenid mussels, well-known invaders of the northern hemisphere, also constitute good biomonitors for freshwater quality assessment. Whereas the oldest, Dreissena polymorpha, is relatively well-known, the new invasive, Dreissena rostriformis bugensis, has been very little characterized. The aim of this study was to compare subcellular biomarker responses within these species, by taking into account inter- and intra-specific variability in biomarker responses during a multi-stress assessment. Indeed, due to local environmental conditions and genetic background, biomarker responses can be different between populations of a given species, not only between species. To evaluate these differential responses, we sampled mussels on two sites where they are both present in sympatry (plus another D. r. bugensis population), and we exposed these populations in laboratory to different stressors: thermal stress (12 or 17 °C), dietary stress (fed or unfed), contamination (nickel at 0, 20 and 500 μg L^-1) and exposure duration (0, 4 or 8 days). Results mainly evidenced strong inter-species and inter-population differences, underlining the need to discriminate correctly between the two species and to know well the populations used in biomonitoring. Results also evidenced thermal and food stress-related effects. The numerous data obtained during this multi-stress experiment also highlight the complexity of working on several stressors and analysing the associated results.

Mussel digestive gland as a model tissue for assessing xenobiotics: An overview

Control strategies and routine biomonitoring programs are commonly performed worldwide using sentinel marine invertebrates, such as mussels of the genus Mytilus, for assessing the "health status" of the aquatic environment. Those species can accumulate and tolerate xenobiotics at levels higher than those being present into the aquatic environment, thus providing accurate and reliable biological endpoints (e.g. physiological, behavioral, cellular, biochemical and molecular indices) that can be measured in their tissues. Taking under consideration the significance of bivalves for assessing the environmental hazard of xenobiotics being present into the water medium, as well as the key role of digestive gland as a target-tissue for the compounds ingested in the organism, the present study aimed to summarize available data on the effects of different categories of xenobiotic compounds, previously characterized as a potential threat for the marine ecosystems. In this context, different types of pharmaceuticals and personal care products (PPCPs), biocides, microplastics (MPs) and nanoparticles (NPs), currently investigated in mussels' digestive gland, using a battery of experimental approaches and analytical methods, as well as stress indices evaluation, are briefly described and further discussed in order to elucidate not only the presence and the toxic mode of action of xenobiotics, but also the important role of the digestive gland as a reliable target-tissue for investigating the effects of xenobiotics at cellular, biochemical, and molecular levels.

Biochemical responses of the Protaetia brevitarsis Lewis larvae to subchronic copper exposure

Copper (Cu) is one of the most commonly detected heavy metals in livestock manure pollution. Protaetia brevitarsis Lewis larvae are widely used in the decomposition of livestock manure. During decomposition, heavy metals in livestock manure can accumulate in P. brevitarsis larvae and affect normal growth and reproduction. Therefore, this research focused on characterizing the toxic effects of Cu to P. brevitarsis Lewis larvae. Larvae were exposed to Cu concentrations of 0, 100, 200, 400, and 800 mg kg^-1 in edible fungi residue for 7, 14, 21, and 28 days. Results showed that the soluble protein content was markedly increased in 200 and 400 mg kg^-1 treatment groups on day 28. Compared to the control group, superoxide dismutase (SOD) and glutathione S-transferase (GST) activities were significantly stimulated on day 7 and then decreased as exposure length was increased (e.g., after 14, 21, and 28 days). Catalase (CAT) activity was also significantly increased after 7 days of exposure. Malondialdehyde (MDA) levels were markedly increased in the 100, 200, and 400 mg kg^-1 treatment groups on day 7. However, as time and Cu concentration were increased, MDA levels gradually decreased. These results indicate that Cu has biochemical effects on P. brevitarsis Lewis larvae, and both time and dose affect this biochemical response.

Current Challenges in Plant Eco-Metabolomics

The relatively new research discipline of Eco-Metabolomics is the application of metabolomics techniques to ecology with the aim to characterise biochemical interactions of organisms across different spatial and temporal scales. Metabolomics is an untargeted biochemical approach to measure many thousands of metabolites in different species, including plants and animals. Changes in metabolite concentrations can provide mechanistic evidence for biochemical processes that are relevant at ecological scales. These include physiological, phenotypic and morphological responses of plants and communities to environmental changes and also interactions with other organisms. Traditionally, research in biochemistry and ecology comes from two different directions and is performed at distinct spatiotemporal scales. Biochemical studies most often focus on intrinsic processes in individuals at physiological and cellular scales. Generally, they take a bottom-up approach scaling up cellular processes from spatiotemporally fine to coarser scales. Ecological studies usually focus on extrinsic processes acting upon organisms at population and community scales and typically study top-down and bottom-up processes in combination. Eco-Metabolomics is a transdisciplinary research discipline that links biochemistry and ecology and connects the distinct spatiotemporal scales. In this review, we focus on approaches to study chemical and biochemical interactions of plants at various ecological levels, mainly plant⁻organismal interactions, and discuss related examples from other domains. We present recent developments and highlight advancements in Eco-Metabolomics over the last decade from various angles. We further address the five key challenges: (1) complex experimental designs and large variation of metabolite profiles; (2) feature extraction; (3) metabolite identification; (4) statistical analyses; and (5) bioinformatics software tools and workflows. The presented solutions to these challenges will advance connecting the distinct spatiotemporal scales and bridging biochemistry and ecology.

Transgenerational Effects of Toxicants: An Extension of the Daphnia 21-day Chronic Assay?

The assessment of transgenerational effects should be incorporated in standard chronic toxicity protocols for the sake of a realistic extrapolation of contaminant effects to the population level. We propose a simple add-on to the standard 21-day chronic Daphnia magna assay, allowing the assessment of the reproductive performance of the offspring (F₁ generation) born from the first clutch of the parental (F₀) generation. The extended generational assay was performed simultaneously with the standard reproduction assay. With this design, we evaluated the lethal, reproductive, and transgenerational effects of four widespread and extensively used substances: a biocide/anti-fouling (copper sulphate), an industrial oxidizing agent (potassium dichromate), a pharmaceutical (paracetamol), and a quaternary ammonium compound (benzalkonium chloride). Benzalkonium chloride was the most toxic in terms of lethality, whereas paracetamol, copper sulphate, and potassium dichromate caused deleterious effects in the reproductive performance of exposed D. magna. Adverse effects in the fitness of the daughter (F₁) generation were observed in the case of maternal exposure to paracetamol and copper sulphate, although they were not very pronounced. These findings highlight the usefulness of our approach and reinforce the view-shared by other authors-of the need for a generalised formal assessment of the transgenerational effects of pollutants.

Emergent synergistic lysosomal toxicity of chemical mixtures in molluscan blood cells (hemocytes)

The problem of effective assessment of risk posed by complex mixtures of toxic chemicals in the environment is a major challenge for government regulators and industry. The biological effect of the individual contaminants, where these are known, can be measured; but the problem lies in relating toxicity to the multiple constituents of contaminant cocktails. The objective of this study was to test the hypothesis that diverse contaminant mixtures may cause a greater toxicity than the sum of their individual parts, due to synergistic interactions between contaminants with different intracellular targets. Lysosomal membrane stability in hemocytes from marine mussels was used for in vitro toxicity tests; and was coupled with analysis using the isobole method and a linear additive statistical model. The findings from both methods have shown significant emergent synergistic interactions between environmentally relevant chemicals (i.e., polycyclic aromatic hydrocarbons, pesticides, biocides and a surfactant) when exposed to isolated hemocytes as a mixture of 3 & 7 constituents. The results support the complexity-based hypothesis that emergent toxicity occurs with increasing contaminant diversity, and raises questions about the validity of estimating toxicity of contaminant mixtures based on the additive toxicity of single components. Further experimentation is required to investigate the potential for interactive effects in mixtures with more constituents (e.g., 50-100) at more environmentally realistic concentrations in order to test other regions of the model, namely, very low concentrations and high diversity. Estimated toxicant diversity coupled with tests for lysosomal damage may provide a potential tool for determining the toxicity of estuarine sediments, dredge spoil or contaminated soil.

Acetylcholinesterase of mangrove oyster Crassostrea rhizophorae: A highly thermostable enzyme with promising features for estuarine biomonitoring

Enzyme biomarkers from several aquatic organisms have been used for assessing the exposure to contaminants at sublethal levels. Amongst them, the cholinesterases are commonly extracted from several organisms to evaluate/measure organophosphate and carbamate neurotoxic effects. Acetylcholinesterase (AChE; EC 3.1.1.7) is an enzyme of the group of serine esterases that acts on the hydrolysis of the neurotransmitter acetylcholine allowing the intermittence of the nerve impulses responsible for the neuronal communication. This enzyme is the main target for the action of some pesticides and the inhibition of its activity in bivalve mollusks may be used as biomarker due to their filter-feeding habit. In this context, the present study aimed to characterize physicochemical and kinetic parameters of the AChE extracted from gills and viscera of the oyster Crassostrea rhizophorae and investigate the in vitro effect of pesticides (dichlorvos, diazinon, chlorpyrifos, methyl-parathion, temephos, carbaryl, carbofuran, aldicarb, diflubenzuron and novaluron) in search for assessing its potential as biomarker. Specific substrates and inhibitors evidenced the predominance of AChE in both tissues. The optimum pH found for gills and viscera AChE were 8.0 and 8.5, respectively. The maximum peak of activity occurred at 70 °C for gill AChE and 75 °C for viscera AChE. The enzymes of both tissues presented remarkable thermostability. The Michaelis-Menten constant for both enzymes were 1.32 ± 0.20 mM for gills and 0.43 ± 0.12 mM for viscera. The V_max values for gills and viscera were 53.57 ± 1.72 and 27.71 ± 1.15 mU/mg, respectively. The enzymes were able to reduce the activation energy to 9.75 kcal mol^-1 (gills) and 11.87 kcal mol^-1 (viscera) obtaining rate enhancements of 3.57 × 10⁵ and 1.01 × 10⁴, respectively, in relation to non-catalyzed reactions. Among the pesticides under study, the carbamates carbaryl and carbofuran exerted the strongest inhibitory effects on the enzyme activity achieving important degrees of inhibition at concentrations below national and international current regulations. The first observation of the effects of benzoylurea pesticides (diflubenzuron and novaluron) on AChE from mollusks is reported here. The gills AChE of C. rhizophorae showed potential to be specific biomarker for the carbamate carbaryl while the viscera AChE showed it for carbofuran. According to their features, these enzymes may be proposed as promising tools for estuarine monitoring as well as biocomponent of biosensor devices.

Uptake and biological responses in land snail Cornu aspersum exposed to vaporized CdCl2

The uptake of Cd and some biomarkers of exposure and effects have been investigated in specimens of land snail Cornu aspersum exposed to vaporized CdCl₂ (10mg/L) for 7 days. The Cd levels quantified in snail's whole bodies confirmed Cd bioavailability trough vaporization and an higher accumulation in the midgut gland compared to the foot. Biological responses investigated showed a reduction of destabilization time of lysosomal membranes (NRRT) in hemocytes and an induction of catalase activities (CAT) in midgut gland. A further evidence of CdCl₂ vaporized exposure was given by an increase in MT protein content as well as induction of Cd-MT gene expression, highlighting the central role of the midgut gland in Cd detoxification. These biomarkers can thus be considered as sensitive tools for the assessment of Cd contamination in the air using land snails as bioindicators. No changes in of GST activity and MDA were observed. From the overall results, the land snail, C. aspersum, could be used as good bioindicator of air quality for pollution monitoring purposes having shown clear signs of exposure and effects due Cd exposure by air.

Role of mTOR in autophagic and lysosomal reactions to environmental stressors in molluscs

Lysosomal membrane stability (LMS) has been used in various organisms as a very sensitive biomarker of stress. However, despite the abundance of data about regulation of the autophagic process in mammals, in the invertebrates there is only limited mechanistic understanding. Marine mussels (Mytilus galloprovincialis Lam.) are bivalve molluscs, widely used as models in ecotoxicology and as environmental bioindicators of sea water quality. In order to elucidate this fundamental process, in the present study, mussels were exposed for 3 days to a "priority", ubiquitous environmental contaminant, benzo[a]pyrene (B[a]P) at different concentrations (i.e. 5, 50, 100 μg/L seawater). B[a]P accumulated in lysosomes of digestive tubule epithelial cells (digestive cells) and in enlarged lipid-rich lysosomes (autolysosomes) as detected by immunofluorescence and UV-fluorescence. B[a]P also activated the autophagic process with a marked decrease of LMS and concurrent increase in lysosomal/cytoplasmic volume ratio. Dephosphorylation of mTOR contributes to increased lysosomal membrane permeability and induced autophagy. B[a]P induced a decrease in phosphorylated (active form) mTOR. The probable role of mTOR in cell signalling and the regulation of the cellular responses to the contaminants has been also confirmed in a field study, where there was significant inactivation of mTOR in stressed animals. Statistical and network modelling supported the empirical investigations of autophagy and mTOR; and was used to integrate the mechanistic biomarker data with chemical analysis and DNA damage.

Mode of action characterization for adverse effect of propranolol in Daphnia magna based on behavior and physiology monitoring and metabolite profiling

Studies are underway to gather information about the mode of action (MOA) of emerging pollutants that could guide practical environmental decision making. Previously, we showed that propranolol, an active pharmaceutical ingredient, had adverse effects on Daphnia magna that were similar to its pharmaceutical action. In order to characterize the mode of action of propranolol in D. magna, which is suspected to be organ-specific pharmaceutical action or baseline toxicity, we performed time-series monitoring of behavior along with heart rate measurements and nuclear magnetic resonance (NMR) based metabolite profiling. Principle component analysis (PCA) and hierarchical clustering were used to categorize the mode of action of propranolol among 5 chemicals with different modes of action. The findings showed that the mode of action of propranolol in D. magna is organ-specific and vastly different from those of narcotics, even though metabolite regulation is similar between narcotic and non-narcotic candidates. The method applied in this study seems applicable to rapid characterization of the MOA of other cardiovascular pharmaceutical ingredients.

Toxicity Evaluation of Graphene Oxide and Titania Loaded Nafion Membranes in Zebrafish

The use of nanomaterials in several application fields has received in the last decades a great attention due to their peculiar properties, but also raised many doubts about possible toxicity when these materials are used for some specific applications, such as water purification. Indeed a careful investigation is needed in order to exclude possible harmful side effects related to the use of nanotechnology. Nanoparticles effects on the marine organisms may depend on their chemical composition, size, surface structure, solubility, shape and how the individual nanoparticles aggregate together. In order to make the most of their potential, without polluting the environment, many researchers are trying to trap them into some kind of matrix that keeps them active but avoids their dispersion in the environment. In this study we have tested nanocomposite membranes prepared using Nafion polymer combined with various fillers, such as anatase-type TiO2 nanoparticles and graphene oxide. The non-toxicity of these nanocomposites, already shown to be effective for water purification applications in our previous studies, was recognized by testing the effect of the different materials on zebrafish embryos. Zebrafish was considered an excellent model for ecotoxicological studies and for this motivation zebrafish embryos were exposed to different concentrations of free nanoparticles and to the nanocomposite membranes. As biomarkers of exposure, we evaluated the expression of heme-oxygenase 1 and inducible Nitric Oxide Synthases by immunohistochemistry and gene expression. Embryo toxicity test showed that nor sublethal effects neither mortality were caused by the different nanoparticles and nano-systems tested. Only zebrafish larvae exposed to free nanoparticles have shown a different response to antibodies anti-heme-oxygenase 1 and anti- inducible Nitric Oxide Synthases. The immunolocalization analysis in fact has highlighted an increase in the synthesis of these biomarkers.

A comprehensive evaluation of the environmental quality of a coastal lagoon (Ravenna, Italy): Integrating chemical and physiological analyses in mussels as a biomonitoring strategy

This study aimed at evaluating the environmental quality of a coastal lagoon (Pialassa Piomboni, NW-Adriatic, Italy) by combining analyses of biomarkers of environmental stress and bioaccumulation of contaminants in marine mussels (Mytilus galloprovincialis) transplanted for 28days to six selected sites. Assessed biomarkers encompassed lysosomal endpoints, oxidative stress and detoxification parameters, specific responses to metals, neuro- and genotoxic substances; chemical analyses focused on PAHs, metals, pesticide and pharmaceuticals. Results showed up to a 67-fold bioaccumulation of 4- to 6-ring PAHs, including pyrene, fluoranthene, chrysene and benzo(ghi)perylene in transplanted mussels compared to reference conditions (T0). A 10-fold increase of Fe, Cr and Mn was observed, while pesticides and pharmaceuticals were not or slightly detected. The onset of a significant (p<0.05) general stress syndrome occurred in exposed mussels, as outlined by a 50-57.7% decrease in haemocytes lysosomal membrane stability and an increased lysosomal volume (22.6-26.9%) and neutral lipid storage (18.9-48.8%) observed in digestive gland. Data also revealed a diffuse lipofuscin accumulation (86.5-139.3%; p<0.05) in digestive gland, occasionally associated to a catalase activity inhibition in gill, indicating an increased vulnerability toward pro-oxidant factors. Higher levels of primary DNA damage (258%; p<0.05) and PAH accumulation were found in mussels exposed along the eastern shoreline, hosting a petrochemical settlement. Bioaccumulated metals showed a positive correlation with increased metallothionein content (85-208%; p<0.05) observed in mussels from most sites. Overall, the use of physiological and chemical analyses detected chronic alterations of the mussel health status induced by specific toxicological pathways, proving a suitable approach in the framework of biomonitoring programs of coastal lagoons.

The potential acute and chronic toxicity of cyfluthrin on the soil model organism, Eisenia fetida

In this study, the acute (72h and 14 d) and chronic (28 d and 8 weeks) effects of cyfluthrin on earthworms were evaluated across different endpoints, which are mortality, growth, reproduction and enzyme activities. Cyfluthrin was rated as moderately toxic in 72-h filter paper test and low toxic in 14-day soil test. The exposure of earthworms to cyfluthrin-polluted soil for 8 weeks showed that growth of earthworms was inhibited by cyfluthrin, cocoon production and hatching were inhibited by 20-60mg/kg cyfluthrin. Moreover, 28-day soil test on the responses of enzymes associated with antioxidation and detoxification showed that the activities of catalase (CAT) and glutathione S- transferase (GST) were initially increased by cyfluthrin at 5-20mg/kg, but reduced at 30-60mg/kg, peroxidase (POD) was increased by 26-102% by cyfluthrin in the early period, except 5mg/kg on day 7, and ethoxyresorufin-O-deethylase (EROD) was increased by 29-335% by cyfluthrin after 3 days. Cyfluthrin degraded with a half-life of 24.8-34.8 d, showing the inconsistency between the continuous toxic responses of earthworms and degradation of cyfluthrin in soil. The variable responses of these indexes indicated that different level endpoints should be jointly considered for better evaluation of the environmental risk of contaminants in soil.

Proliferation, survival and cell death in fish gills remodeling: From injury to recovery

Pollutants found dispersed in water can cause irritations on the gills, challenge the immune system and prejudice the welfare of the fish. Here we investigated molecules linked to proliferation, survival, and cell death, as well as inflammatory and vascular control, in a model of fish gill remodeling, from injury to recovery. We assessed the gill histology and immunohistochemistry for PCNA, iNOS, HSP70, and Bax in Hypostomus francisci obtained from a river subjected to chronic anthropic influences and then after they were placed in water of good quality. A total of 30 H. francisci adult individuals were collected and distributed into two groups: euthanized on the day of capture (group 1) and maintained for 30 days in an aquarium (group 2). In all the fish from group 1, the primary and secondary lamellae showed hypertrophy of the respiratory epithelium, lamellar fusion, lifting of the epithelium, aneurysm, hyperemia, and vascular congestion. On the other hand, in all the fish from group 2, restoration of gill integrity was observed, and the primary and secondary lamellae showed a simple epithelium, absence of lamellar fusion, hypertrophy, and aneurysm. Gills of fish from group 1 had higher frequency of cells immunopositive for PCNA, iNOS, HSP70, and Bax than those of fish from group 2 (p < 0.05). The molecular and cellular mechanisms from injury to recovery were proposed, with a balance between survival and cell death signals being essential for determining the gill structure. In addition, the findings indicate that recovery of the structural organization of gills is possible if fishes are maintained in good-quality water, indicating the importance of the conservation of aquatic environments.

Response of the pearl oyster Pinctada margaritifera to cadmium and chromium: Identification of molecular biomarkers

This study was designed to identify in the pearl oyster Pinctada margaritifera, used as a bio-accumulator, molecular biomarkers for the presence of heavy metals in the lagoon environment. Pearl oysters were exposed to 2 concentrations (1 and 10μgL^-1) of cadmium (Cd) and chromium (Cr) compared to a control. Twelve target genes encoding proteins potentially involved in the response to heavy metal contamination with antioxidant, detoxification or apoptosis activities were selected. P. margaritifera accumulated Cd but not Cr, and mortality was related to the amount of Cd accumulated in tissues. In response to Cd-Cr contamination, metallothionein (MT) was significantly up-regulated by Cd-Cr at both concentrations, while 7 others (SOD, CAT, GPX, GSTO, GSTM, CASP, MDR) were down-regulated. Based on the development of these molecular tools, we propose that the pearl oyster, P. margaritifera, could be used as a sentinel species for heavy metal contamination in the lagoons of tropical ecosystems.

Shell fluctuating asymmetry in the sea-dwelling benthic bivalve Mytilus galloprovincialis (Lamarck, 1819) as morphological markers to detect environmental chemical contamination

Investigations on asymmetries showed that deviations from perfect bilateral symmetry are interpreted as environmental changes inducing developmental instability. Since morphological abnormalities increase with pollution, deformations may be considered indicators of the organism exposition to pollution. Therefore, the onset of asymmetry in otherwise normally symmetrical traits has been used as a measure of some stresses as well. In this context, we studied how marine pollution affects the valve morphological alterations in the mussel Mytilus galloprovincialis. We used 180 specimens (30 per site) from the aquaculture area of Goro (River Po delta, northern Adriatic Sea), translocated, and released within 50 × 50 × 50 cm cages in five sites: two disturbed and one undisturbed near Naples (eastern Tyrrhenian Sea), and one disturbed and one undisturbed near Siracusa (western Ionian Sea). Disturbed sites were stressed by heavy industrialization and heavy tankers traffic of crude and refined oil, and were defined basing on sediment contamination. In particular, by the cone-beam computed tomography we obtained 3D virtual valve surfaces to be analyzed by the geometric morphometric techniques. Specifically, we focused the levels of the shell shape fluctuating asymmetry in relation to the degrees of marine pollution in different sites of the Tyrrhenian Sea. The Mahalanobis distances (interpreted as proxy of the individual shape asymmetry deviation from the mean asymmetry) significantly regressed with the sediment contamination gradient. Indeed, although the left-right differences were normally distributed in each studied site, the individual asymmetry scores (IAS) significantly varied amongst the investigated sites. IAS showed higher values in disturbed areas than those of undisturbed ones in both Tyrrhenian and Ionian Sea. Our results are consistent with past studies on molluscans and other taxa, demonstrating some detrimental effects of chemicals on organisms, although the investigated morphological marker did not discriminate the real disturbance source. Our findings indicate that the mussels act as a prognostic tool for sea pollution levels driving detrimental effects on benthic community.