Measurement of Carboxylesterase ( CES ) Activities

The ecotoxicological effects of diclofenac and gentamicin on Mytilus galloprovincialis: What does in vivo reveal that in vitro fails to show?

This study investigated the toxicological effects of diclofenac (DIC) and gentamicin (GEN) on the gills (G) and digestive gland (DG) of Mytilus galloprovincialis through in vitro and in vivo assays. Biochemical markers related to oxidative stress, metabolic capacity, and neurotoxicity were evaluated at the end of each assay. For both assays, principal coordinates analysis (PCO) highlighted distinct biochemical profiles between G and DG, mostly related to higher basal values for several biomarkers in DG.The Integrated Biomarker Response (IBR) index revealed the highest scores in G for the in vitro assay, especially after exposure to GEN. In the in vivo assay, instead, the highest scores were recorded in DG, particularly in response to DIC. The distinct responses of G and DG underscore their respective roles in respiration and detoxification, with G being more sensitive to acute stress and DG exhibiting greater adaptive capacity over time. Furthermore, GEN appeared to cause the greatest impact on G in the in vitro assay, while DIC had the most significant effect on DG following the in vivo experiment. In vitro assays demonstrated limited oxidative stress and cellular damage, while in vivo results highlighted substantial metabolic depression and biomarker variability under prolonged exposure. When analyzed individually, the in vitro assay showed a clearer distinction between the two contaminants, particularly in DG. The findings underscore the differential vulnerability and adaptive capacities of G and DG, attributed to their distinct physiological functions. These results emphasize the complementary nature of in vitro and in vivo approaches, with the former providing mechanistic insights and the latter reflecting systemic organismal responses. This study highlights the importance of a multi-dimensional approach, combining both in vitro and in vivo methodologies, to better understand tissue-specific toxicity and the broader ecological consequences of pharmaceutical contamination.

Transcriptomic and biochemical analysis of Procambarus clarkii upon exposure to pesticides: Population-specific responses as a sign of pollutant resistance?

The effects that anthropogenic stressors may have on modulating species' plasticity has been relatively unexplored; however, it represents a scientific frontier that may offer insights into their ability to colonize new habitats. To explore the advantage that inhabiting polluted environments may offer to invasive species, we selected the crayfish Procambarus clarkii, a species that can colonize and thrive in a wide range of aquatic environments, including heavily polluted ones. Here, we studied the molecular and physiological responses of crayfish when experimentally exposed to a pesticide mix of azoxystrobin and oxadiazon at sublethal concentrations. We compared these responses in three isolated crayfish populations in Southern France that are established in areas with different pollution levels: i) Camargue, seasonally affected by pesticide pollution; ii) Bages-Sigean, impacted all year-round by domestic effluents and; iii) Salagou, a more pristine site. Gene expression analyses revealed that the response to the pesticide mix was the strongest in the Camargue crayfish. In this population, a total of 88 differentially expressed genes (DEGs) were identified in hepatopancreas and 78 in gills between exposed and control laboratory groups. Among genes that were differentially expressed and successfully annotated, those involved in stress response, DNA repair, immune response, and translation and transcription processes stand out. Interestingly, the hepatopancreas responded mainly with up-regulation, while the gills showed down-regulation. Our results demonstrate population-specific responses to pesticide stress in populations with different life-history of exposure to pollutants. The high regulation of the aforementioned mechanisms indicates that they play a crucial role in the adaptation of this invasive species to polluted environments.

Revealing hidden risks: in vitro analysis of PFAS hazards in Mytilus galloprovincialis gills and digestive gland

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals known for their persistence and bioaccumulation, leading to widespread environmental contamination. Despite their recognised environmental risks, particularly to aquatic wildlife, including marine invertebrates, detailed impact studies are limited. PFAS can be categorised according to the length of the compound chain, with short-chain PFAS announced as a safer alternative to the more commonly used long-chain PFAS. However, recent evidence suggests that also short-chain PFAS pose significant environmental risks. The present study evaluated the adverse effects of six PFAS compounds-two short-chain (PFHxA, 6:2 FTA) and four long-chain (PFUnDA, PFDoA, PFTriDA, PFTeDA)- on the digestive gland and gills of mussels, Mytilus galloprovincialis, using in vitro assays. The results showed organ-specific responses: the digestive gland was more sensitive to PFHxA, with increased catalase activity and decreased total antioxidant capacity, and cellular damage was observed only at higher concentrations of PFTriDA. Gills were more affected by PFDoA and PFTeDA, with inhibited antioxidant enzyme activity and increased oxidative stress. PFHxA and PFTriDA also showed inhibition of acetylcholinesterase activity. 6:2 FTA had the lowest effects for both organs, while PFHxA was the most harmful. These findings underscore the need for thorough risk assessments of PFAS, considering both chain length and organ-specific effects.

Could Mussel Populations Be Differentially Threatened by the Presence of Microplastics and Related Chemicals?

Mussels serve as indicators of anthropogenic chemical pollution; however, the effects of microplastics and plastic-related chemicals on their health performance remain an emerging issue. In this study, mussels were exposed to a polyamide (PA; 5 μg/L) and tricresyl phosphate (TCP; 1 μg/L) for 28 days. The exposures to the two contaminants were performed independently or in combination and lasted 28 days. The results showed that the independent exposure altered enzyme activities more significantly than the combined one. Exposure to the PA significantly (p < 0.05) inhibited the antioxidant enzyme catalase (CAT) by 43.5% and the neurotransmitter enzyme acetylcholinesterase (AChE) by 40.6%, while TCP specifically inhibited carboxylesterase (CE) activity by 38.5%, all in respect to the solvent control. When both pollutants were combined, most biomarker responses were similar to control levels. To further investigate if the mussels' response to contaminants (here, chemical compounds only) could be population-specific, a comparative study between Atlantic and Mediterranean mussels was included. Firstly, baseline detoxification defenses were contrasted in the digestive glands of each mussel population, followed by an assessment of in vitro responses to a wide range of plastic additives. The results revealed that Mediterranean mussels expressed higher baseline activities for most detoxification enzymes, although the in vitro sensitivity to the targeted chemicals was similar in both populations. Of all the plastic additives tested, TCP significantly inhibited CE activity both in vivo and in vitro. The in vitro screening also indicated that other plastic additives could act as strong inhibitors of CE. However, additional in vivo exposures in mussels are needed to confirm CE suitability as a biomarker of these chemical exposures. All together, these results also suggest critical population-level differences in susceptibility to microplastic pollution, highlighting a need for targeted conservation efforts.

Sediment contamination in two German estuaries: A biomarker-based toxicity test with the ragworm Hediste diversicolor under intermittent oxygenation

Toxicity testing is an important tool for risk assessment of sediment contamination in estuaries. However, there has been a predominant focus on fitness parameters as toxic endpoints and on crustaceans as test organisms, while effects at the sub-organismal level and on other benthic taxa have received less attention. Also, interactions between sediment contamination and natural stressors such as oxygen are often neglected in traditional toxicity tests. Here we conducted a toxicity test of sediments from the Elbe and Oder (Odra) estuaries under three weeks of continuous and intermittent oxygenation, using biomarkers in an annelid, the ragworm Hediste diversicolor. Contaminated sediments affected worm survival and some biomarkers of antioxidant defense, electrophilic stress, and energy status with response ratios of above 20%. Toxic effects were most pronounced in sediments from the upper Elbe estuary, which contained high levels of heavy metals and organic chemicals. Oxygen regimes hardly changed the sediment effects, suggesting the robustness of the biomarker-based toxicity test with ragworms.

Interplay of UV-filter pollution and temperature rise scenarios on Mytilus galloprovincialis health: Unveiling sperm quality and adult physiology, biochemistry, and histology insights

Addressing the impacts of emerging contaminants within the context of climate change is crucial for understanding ecosystem health decline. Among these, the organic UV-filters 4-methylbenzylidenecamphor (4-MBC) and benzophenone-3 (BP-3) are widely used in cosmetics and personal care products. Their unique physico-chemical properties, along with their growing commercialization and consumption, have made them ubiquitous in aquatic environments through both direct and indirect releases, raising significant concerns about their potential threats to inhabiting biota. Additionally, increasing surface water temperatures exacerbate ecological risks, making it imperative to understand the implications for non-target species at different biological levels. This study investigated the short- and long-term effects of UV-filters 4-MBC or BP-3, at ecologically relevant concentrations, combined with current and predicted warming scenarios, on the performance and male reproductive health of Mytilus galloprovincialis mussel populations. Using biomarkers across sub-cellular, cellular, tissue, and individual levels, the study revealed significant physiological and biochemical impairments in both sperm cells and adults exposed to UV-filters. Temperature emerged as the primary driver influencing mussel responses and modulating the impacts of 4-MBC/BP-3, emphasizing their sensitivity to temperatures outside the optimal range and interactive effects between stressors. Specifically, sperm motility declined with increasing UV-filter concentrations, while temperature alone influenced ROS production, leading to compromised mitochondrial activity and DNA damage in the presence of combined stressors, indicative of potential reproductive impairments. Adults exhibited high UV-filter bioconcentration potential in whole tissues, compromised physiological status, morphophysiological changes in digestive glands, oxidative stress, and alterations in metabolic capacity, antioxidant defences, and biotransformation mechanisms, correlating with UV-filter exposure and temperature increase. Among the UV-filters tested, 4-MBC was the most detrimental, especially when combined with warming. Overall, this study underscores the vulnerability of M. galloprovincialis to cumulative stressors and highlights the importance of employing a multi-biomarker approach to assess and mitigate the impacts of stressors on coastal ecosystems.

Evaluating the impact of gadolinium contamination on the marine bivalve Donax trunculus: Implications for environmental health

Gadolinium (Gd), commonly used in contrast agents for medical imaging, has been detected in hospital wastewater and aquatic environments, raising environmental concerns. This study examined the accumulation and cellular impacts of Gd in the clam species Donax trunculus, commonly used as bioindicator of contamination. Gadolinium accumulation in clams increased with exposure and over time. Biological responses varied with Gd levels: low concentrations (10 and 50 µg/L) led to low metabolic activity and glycogen content, but high antioxidant activities and lipid peroxidation levels (LPO); high concentrations (250 and 500 µg/L) resulted in increased metabolic activity, while antioxidant enzyme activity was inhibited and LPO levels were the lowest. Metabolic activity decreased after two weeks, suggesting limited long-term metabolic resilience. The study underscores D. trunculus as an effective early warning species for Gd pollution and highlights the ecological risks of rising Gd levels, emphasizing the need for environmental monitoring and regulation.

Stress indicators in conservative tissues of Humboldt penguin under captivity

Humboldt penguins (Spheniscus humboldti) from the Barcelona zoo (n=9) were followed to assess their physiological stress status using conservative protocols. Corticosterone levels were measured in feathers and plasma as indicative of chronic and acute physiological stress, respectively. Other markers: B-esterases, potentially indicative of xenobiotic exposure were measured in plasma of these same individuals and reported for the first time in this species. The sensitivity to chemicals of environmental concern, employed as plastic additives, was assessed in vitro with plasma of this species using the inhibition of carboxylesterase (CE) and acetylcholinesterase enzymatic measurements. Among the tested additives, the organophosphorus flame retardants displayed the highest in vitro inhibitory potential on basal CE activity, suggesting their potential utility as biomarkers of this particular chemical class. Additionally, enzymatic measurements in plasma are determined for the first time in Humboldt penguin and can be regarded as baseline values for a potential field monitoring application.

Veterinary fluoroquinolones as emerging contaminants in marine environments: In vitro study of biochemical responses in subcellular fractions of the Mediterranean mussel (Mytilus galloprovincialis)

Fluoroquinolone antibiotics (FQs) are emerging pollutants frequently detected in aquatic environments. However, their impact on marine invertebrates remains underexplored. This study investigated the responses at subcellular level in the Mediterranean mussel (Mytilus galloprovincialis) exposed to three veterinary FQs, marbofloxacin (MARB), sarafloxacin (SARA), and difloxacin (DI), at concentrations considered relevant to environmental conditions. The assessment focused on the digestive gland and gills, employing in vitro assays to evaluate antioxidant defenses, biotransformation, and neurotransmission enzyme activities, as well as their effects on membrane lipids, proteins, and DNA integrity. Results revealed a general decline in antioxidant defenses and compromised DNA integrity in both tissues. Additionally, exposure to MARB and DI led to an alteration in detoxification capacity in the gills, along with an increased content of carbonylated proteins. Conversely, the digestive gland exhibited a significant inhibition of acetylcholinesterase activity. These findings suggest potential neurotoxic and genotoxic impacts of these antibiotics on non-target species, as well as an associated oxidative effect.

Therapeutic deep eutectic solvent with saponin, optimized through response surface methodology, exert potent in vivo antimicrobial effects against Pseudomonas aeruginosa

Therapeutic deep eutectic solvents (THEDES) are a type of deep eutectics that can be used as active pharmaceutical ingredients (APIs) by enhancing the drug bioavailability, by increasing the solubility of APIs in aqueous solutions or by increasing their permeability through biological barriers. In this study, we demonstrate the utility of designer THEDES, based on Quillaja Saponin (SAP), a triterpene natural product to unravel the antimicrobial potential of such THEDES. THEDES were prepared by gently mixing and heating five different α- hydroxy acids- malic, citric, tartaric, glycolic, lactic acids and SAP with water as a third component in the THEDES. The antimicrobial assays were performed with the as-prepared SAP-THEDES and among the panel of bacterial strains, saponin-malic acid THEDES [SMA-THEDES] displayed potent activity in disassembling PA biofilms, demonstrating that the SMA-THEDES can serve as therapeutic antibacterial biomaterials. To further optimize, a Box-Behnken- response surface methodology (RSM) experimental design was done and at the optimum conditions of SAP (1.014 m.mol), Malic acid (1.003 m.mol), Water (0.117 m.mol), SMA-THEDES exhibited maximum MIC of P. aeruginosa with the minimum absorbance at 590 nm of 0.105. The effectiveness of SMA-THEDES as antibiofilm agents on P. aeruginosa with the mechanism studies have been explored. The colony count from the in vivo infection zebrafish model in the treatment group showed a decline of > 2 fold for SMA-THEDES. Toxicity studies did not reveal any abnormality in liver and brain enzyme levels. Liver morphology images show no severe cytological alterations when treated with SMA-THEDES and were almost similar to the normal liver.

Mytilus galloprovincialis: A valuable bioindicator species for understanding the effects of diclofenac under warming conditions

Drugs are chemical compounds used to treat and improve organic dysfunctions caused by diseases. These include analgesics, antibiotics, antidepressants, and antineoplastics. They can enter aquatic environments through wastewater streams, where their physico-chemical properties allow metabolites to distribute and accumulate. Current climate change and associated extreme weather events may significantly impact these substances' toxicity and aquatic organisms' sensitivity. Among the chemicals present in aquatic environments is the non-steroidal anti-inflammatory drug diclofenac (DIC), which the EU monitors due to its concentration levels. This study investigated the influence of temperature (control at 17 °C vs. 21 °C) on the effects of DIC (0 μg/L vs. 1 μg/L) in the mussel species Mytilus galloprovincialis. Significant results were observed between 17 and 21 °C. Organisms exposed to the higher temperature showed a decrease in several parameters, including metabolic capacity and detoxification, particularly with prolonged exposure. However, in some parameters, after 21 days, the M. galloprovincialis showed no differences from the control, indicating adaptation to the stress. The results of this study confirm that DIC concentrations in the environment, particularly when combined with increased temperatures, can produce oxidative stress and adversely affect M. galloprovincialis biochemical and physiological performance. This study also validates this species as a bioindicator for assessing environmental contamination with DIC. Beyond its direct impact on aquatic organisms, the presence of pharmaceuticals like DIC in the environment highlights the interconnectedness of human, animal, and ecosystem health, underscoring the One Health approach to understanding and mitigating environmental pollution.

Assessing combined effects of long-term exposure to copper and marine heatwaves on the reef-forming serpulid Ficopomatus enigmaticus through a biomarker approach

Sessile benthic organisms can be affected by global changes and local pressures, such as metal pollution, that can lead to damages at different levels of biological organization. Effects of exposure to marine heatwaves (MHWs) alone and in combination with environmentally relevant concentration of copper (Cu) were evaluated in the reef-forming tubeworm Ficopomatus enigmaticus using a multi-biomarker approach. Biomarkers of cell membrane damage, enzymatic antioxidant defences, metabolic activity, neurotoxicity, and DNA integrity were analyzed. The exposure to Cu alone did not produce any significant effect. Exposure to MHWs alone produced effects only on metabolic activity (increase of glutathione S-transferase) and energy reserves (decrease in protein content). MHWs in combination with copper was the condition that most influenced the status of cell homeostasis of exposed F. enigmaticus. The combination of MHWs plus Cu exposure induced increase of protein carbonylation and glutathione S-transferase activity, decrease in protein/carbohydrate content and carboxylesterase activity. This study on a reef-forming organism highlighted the additive effect of a climate change-related stressor to metals pollution of marine and brackish waters.

Exploring toxicological interactions in a changing sea: The case of the alkaloids caffeine and caulerpin

The bisindolic alkaloid caulerpin (CAU) is a bioactive compound isolated from green algae of the genus Caulerpa that are highly invasive in the Mediterranean Sea. On the other side, the purine alkaloid caffeine (CAF) is one of the most globally consumed psychoactive substances and a widespread anthropogenic water pollutant. Both compounds display a large panel of biological properties and are well known to accumulate in the tissues of aquatic organisms and, in certain circumstances, co-occur in the human diet. On this premise, the present study aimed to investigate possible synergistic interactions between CAU and CAF by using the bivalve Mytilus galloprovincialis as a model organism. Mussels were exposed to CAF via medium while they were fed with food enriched with CAU. After treatments, biochemical analysis confirmed the toxic potential of CAF, with increased AChE activity and lipid peroxidation. Also, histopathological alterations were observed in the gills and digestive tubules. The NMR-based metabolomics analysis detected higher levels of free amino acids under CAF treatments. Conversely, the food administration of CAU did not affect the above toxicological biomarkers. In addition, we did not observe any cumulative effect between CAF and CAU toward increased cellular damage and neurotoxicity. On the other hand, a possible action of CAU in decreasing CAF toxicity could be hypothesized based on our results. This hypothesis is supported by the activity of CAU as an agonist of peroxisome proliferator-activated receptors (PPARs). PPARs mediate xenobiotic detoxification via cytochromes P450, which is involved in CAF metabolism. Overall, the results obtained not only rule out any cumulative adverse effects of CAF and CAU but also encourage further research to evaluate the possible use of CAU, a compound easily obtained through the valorization of biomass from invasive species, as a food additive to improve the clearance of xenobiotics.

Thermoregulatory response in juvenile Hippocampus erectus: Effect of magnitude and rate of thermal increase on metabolism and antioxidative defence

Behavioural, physiological and biochemical mechanisms constitute the adaptive capacities that allow marine ectotherms to explore the environment beyond their thermal optimal. Limitations to the efficiency of these mechanisms define the transition from moderate to severe thermal stress, and serve to characterise the thermoregulatory response in the zone of thermal tolerance. We selected a tropical population of Hippocampus erectus to describe the timing of the physiological and biochemical mechanisms in response to the following increments in water temperature: (i) 4°C abrupt (26-30°C in <5 min); (ii) 7°C abrupt (26-33°C); (iii) 4°C gradual (1°C every 3 h) and (iv) 7°C gradual (1.5°C every 3 h). The routine metabolic rate (Rrout) of juvenile H. erectus was measured immediately before and after 0.5, 12 and 28 h of being exposed to each thermal treatment. Samples of muscle and abdominal organs were taken to quantify indicators of aerobic and anaerobic metabolism and antioxidant enzymes and oxidative stress at each moment throughout exposure. Results showed a full thermoregulatory response within 0.5 h: Rrout increased in direct correspondence with both the magnitude and rate of thermal increase; peroxidised lipids rapidly accumulated before the antioxidant defence was activated and early lactate concentrations suggested an immediate, yet temporary, reduction in aerobic scope. After 12 h, Rrout had decreased in sea horses exposed to 30°C, but not to 33°C, where Rrout continued high until the end of trials. Within 28 h of thermal exposure, all metabolite and antioxidant defence indicators had been restored to control levels (26°C). These findings testify to the outstanding thermal plasticity of H. erectus and explain their adjustment to rapid fluctuations in ambient temperature. Such features, however, do not protect this tropical population from the deleterious effects of chronic exposure to temperatures that have been predicted for the future.

Comparative subcellular responses to pharmaceutical exposures in the mussel Mytilus galloprovincialis: An in vitro study

Pharmaceutical active compounds (PhACs) have raised concerns in the last decade due to their increased consumption and inadequate elimination during discharge, resulting in their introduction into water systems and potential significant threats to non-target organisms. However, few studies have investigated the sublethal impacts of PhAC exposure on marine invertebrates. Thus, the present study aimed to assess tissue-specific responses in Mytilus galloprovincialis to sodium lauryl sulfate (SLS), salicylic acid (SA), and caffeine (CAF) (4.0 mg/L, 4.0 mg/L and 2.0 μg/L, respectively). Short-term in vitro exposures with mussel digestive gland and gill tissues were conducted and biochemical responses related to antioxidant and detoxification capacity, cellular damage and neurotoxicity were assessed. The present results clearly showed significant differences in tissue sensitivity and biochemical responses to the contaminants tested. This study highlights the suitability of filter-feeder species as valuable model organisms for studying the sublethal effects of unintended environmental exposures to PhACs.

Benzophenone-3 does not Cause Oxidative Stress or B-esterase Inhibition During Embryo Development of Octopus maya (Voss and Solís Ramírez, 1966)

Benzophenone-3 (BP-3) is an active ingredient in sunscreen lotions and personal-care products that protects against the damaging effects of ultraviolet rays. Given its worldwide dissemination, it has been linked with harmful effects on aquatic biota; however, its impact is not fully understood calling for further studies. To understand the impacts on an important economically and ecologically species, we evaluated the toxicity of BP-3 during the embryonic development of Octopus maya. Embryos were exposed to increasing concentrations of up to 500 µg BP-3/L until hatching. Antioxidant enzyme activities, oxidative-stress indicators, and B-esterases activities were measured at different developmental phases (organogenesis, activation, and growth). There were no significant differences between treatments, suggesting the lack of production of toxic metabolites that may be related to a protective chorion, an underdeveloped detoxification system, and the experimental conditions that limited phototoxicity.

Subcellular tissues-specific responses of Mytilus galloprovincialis to fluoroquinolone antibiotics

The study aimed to investigate the in vitro effects of the fluoroquinolone antibiotics (FQs) Ciprofloxacin (CIP), Enrofloxacin (ENR) and Danofloxacin (DAN) on the mussel Mytilus galloprovincialis exposed to environmentally relevant concentrations. In vitro exposure was performed on subcellular fractions of the digestive gland and gills through a multi-biomarker approach, which included the assessment of cellular damage, antioxidant and biotransformation enzyme activities, neurotoxicity, and DNA single-strand breaks (DNAssb). Results showed a decrease in protein carbonyl content in the gills when exposed to all concentrations of ENR. A significant overall decrease in the enzymatic activity of antioxidant defences was observed in the digestive gland exposed to the highest concentration of DAN and CIP, with a similar trend observed in the gills. Neurotoxicity was observed in the digestive gland at all tested concentrations of all FQs, but no effects were detected in the gills. DNAssb was evident in both tissues at all higher FQ concentrations.

BBD optimized antioxidants of Crotalaria candicans and its nanoconjugates, exert potent in vivo anti-biofilm effects against MRSA

Crotalaria genus is extensively dispersed in tropical and subtropical provinces, and it is found to harbor antioxidant flavonoids. Response surface methodology-based optimization was carried out for the purpose of efficient extraction involving a suitable solvent which can maximize the yield along with higher total phenolic content and total flavonoid content (TFC). Optimization conditions for extraction of C.candicans flavonoids (CCF) based on variables such as solvent, solid-solvent ratio and extraction temperature were evaluated. The optimized conditions were found as Solvent i.e., Aqueous-ethanol (53.42%), Solid-solvent ratio (1:15.83 w/v) and temperature (44.42 °C) and resulted to obtain the TFC as 176.23 mg QRET/g C. candicans extract with the yield 27.42 mg CCF/g (C. candicans dry weight). LC-MS analysis of CCF, revealed the presence of seven major flavonoids. The antioxidant flavonoids were further used to functionalize the zero-valent silver (ZVAgF) and copper (ZVCuF) nanoparticles. The ZVAgF and ZVCuF were investigated using UV-Vis spectrophotometry, FT-IR spectroscopy and X-ray diffractometry to confirm the presence of the zero valent metals and possible functional groups which capped the elemental metal. Further transmission electron microscopy, dynamic light scattering method and zeta-potential studies were done to understand their respective structural and morphological properties. The efficacy of the as-prepared ZVAgF/ZVCuF as antibiofilm agents on Methicillin-resistant Staphylococcus aureus (MRSA) with the mechanism studies have been explored. The MRSA-colony count from the infection zebrafish (in vivo) model, portrayed a reduction of > 1.9 fold for ZVCuF and > twofold for ZVAgF, with no alteration in liver morphology when treated with ZVAgF, implying that the nanoparticles were safe and biocompatible.

Ecotoxicological impacts of metals in single and co-exposure on mussels: Comparison of observable and predicted results

Used in high-tech and everyday products, mercury (Hg), cobalt (Co), and nickel (Ni) are known to be persistent and potentially toxic elements that pose a serious threat to the most vulnerable ecosystems. Despite being on the Priority Hazardous Substances List, existing studies have only assessed the individual toxicity of Co, Ni and Hg in aquatic organisms, with a focus on the latter, ignoring potential synergistic effects that may occur in real-world contamination scenarios. The present study evaluated the responses of the mussel Mytilus galloprovincialis, recognized as a good bioindicator of pollution, after exposure to Hg (25 μg/L), Co (200 μg/L) and Ni (200 μg/L) individually, and to the mixture of the three metals at the same concentration. The exposure lasted 28 days at 17 ± 1 °C, after which metal accumulation and a set of biomarkers related to organisms' metabolic capacity and oxidative status were measured. The results showed that the mussels could accumulate metals in both single- and co-exposure conditions (bioconcentration factors between 115 and 808) and that exposure to metals induced the activation of antioxidant enzymes. Although Hg concentration in organisms in the mixture decreased significantly compared to single exposure (9.4 ± 0.8 vs 21 ± 0.7 mg/kg), the negative effects increased in the mixture of the three elements, resulting in depletion of energy reserves, activation of antioxidants and detoxification enzymes, and cellular damage, with a hormesis response pattern. This study underscores the importance of risk assessment studies that include the effects of the combination of pollutants and demonstrates the limitations of applying models to predict metal mixture toxicity, especially when a hormesis response is given by the organisms.

B-esterase measurements and other blood related biomarkers in loggerhead sea turtles (Caretta caretta) as indicators of health status

The loggerhead sea turtle (Caretta caretta) has been selected as sentinel species by the Marine Strategy Framework Directive (MSFD) descriptor 10 in relation to marine litter. In this, and other protected species, there is a need to develop conservative pollution biomarkers equally informative of chemical exposures to those traditionally carried out in metabolic organs, such as the liver. With this aim, plasma from turtles undergoing rehabilitation at the Fundació Oceanogràfic rescue centre (Arca del Mar) were selected and tested for B-esterase measurements. Hydrolysis rates of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and carboxylesterases (CEs) using four commercial substrates were undertaken on 191 plasma samples. Results indicated that acetylthiocholine was the most adequate substrate of cholinesterases and butyrate esters for CE measures. The correlation of these parameters with well-established blood biochemistry measurements was analysed. B-esterase measures in wild specimens were discussed in relation to age group, pathology on admission to the rescue centre and season; moreover, contrasts with long-term resident turtles were also made. Although this study provides baseline data on B-esterase measures in a large sample size for this species, more complementary information is still needed in terms of population genetics, chemical exposures, and in relation to other biochemical parameters before they can be confidently applied in wild specimens within the regulatory MSFD.

Are Lithium batteries so eco-friendly? Ecotoxicological impacts of Lithium in estuarine bivalves

Lithium (Li) is now widely used in green energies/clean technologies, although its inefficient recycling and treatment means it is an emerging contaminant in aquatic systems. Bivalves, such as clams, are considered good bioindicators of pollution, hence we evaluated the biochemical effects of Li in the clam Venerupis corrugata. Clams were exposed (14 days) to an increasing Li gradient (0, 200, 400, 800µg/L). Bioconcentration capacity tended to decrease with increasing Li exposure possibly due to efforts to eliminate Li from the cells, to avert damage. No influences on the clams' metabolic capacity and protein content were observed. Antioxidant and detoxification defences were activated, especially at 400 and 800µg/L of Li, avoiding lipid damage while protein injuries were observed at higher concentrations. Furthermore, a loss of redox balance was observed. This study highlights the importance of preventing and regulating Li discharges into the environment, avoiding adverse consequences to aquatic ecosystems.

Will warmer summers increase the impact of UV filters on marine bivalves?

Marine organisms are constantly exposed to multiple stressors including pollutants released into the environment, such as personal care products (PCPs), and climate change-derived factors, namely warming, which are aggravated by anthropogenic drivers and pose increasing pressure on coastal ecosystems. Avobenzone (AVO) is one of the most used ultraviolet (UV) filters in PCPs which have been increasingly used and, thereby, identified in aquatic environments. However, data regarding the influence of warming on the impacts caused by AVO in bivalves is lacking. Mussels are considered good bioindicators thus being often employed in ecotoxicology studies. Hence, the present study aimed to evaluate the toxic effects of an environmentally relevant concentration of AVO (0.5 μg/L) and warming (21 °C), acting alone or in combination, on sperm and adults of the Mediterranean mussel species Mytilus galloprovincialis, through in vitro and in vivo tests, respectively. AVO and warming effects were evaluated by assessing oxidative status, viability, genotoxicity, motility, and kinetics in sperm, together with the quantification of energy content, metabolic capacity, biological defence mechanisms, cellular damage, and neurotoxicity in adults. AVO induced genotoxicity and increased respiration rate in sperm while enhancing the biotransformation enzymes' activity in adults. Exposure to warming led to an increase in respiration rate, ROS overproduction, cellular damage, and viability decrease in sperm whereas metabolic capacity increased in adults. AVO combined with warming caused oxidative stress, cellular damage, genotoxicity, and decreased motility in sperm, while only antioxidant enzymes' activity was enhanced in adults. Overall, the present study demonstrated that when acting in combination the effects of both stressors were more prominent. Furthermore, considering the multiple-stressor scenario tested, major toxic effects occurred in male gametes in comparison to adults.

Toxic effects of a mixture of pharmaceuticals in Mytilus galloprovincialis: The case of 17α-ethinylestradiol and salicylic acid

The impact of pharmaceuticals on marine invertebrates has been a topic of rising concern, with an increasing number of studies regarding the impacts on bivalves. However, very few investigated the toxicity of mixtures of pharmaceuticals. This knowledge gap was investigated in the present study, where the toxicity of 17α-ethinylestradiol (EE2) and salicylic acid (SA) mixture was evaluated. To this end, Mytilus galloprovincialis mussels were chronically subjected to both pharmaceuticals, acting alone and in combination, and the effects at the cellular level were measured. The Independent Action (IA) model was performed aiming to compare obtained with predicted responses. The integrated biomarker response (IBR) index was used to assess the overall biochemical response given by mussels. The results obtained revealed that the most stressful condition was caused by the combined effect of EE2 and SA, with the highest metabolic capacity, antioxidant (catalase activity) and biotransformation (carboxylesterases activity) activation and cellular damage in organisms exposed to the mixture of both drugs in comparison to responses observed when each drug was acting alone. Predicted responses obtained from the IA model indicate that caution should be paid as frequent deviations to observed responses were found. This study highlights the need for future studies considering the mixture of pollutants, mimicking the actual environmental conditions.

Heavy metal(loid) effect on multi-biomarker responses in apex predator: Novel assays in the monitoring of white stork nestlings

The goal of the present study was to investigate differences in biomarker responses related to metal(loid)s in white stork (Ciconia ciconia) nestling's blood from continental Croatia. To achieve this, a battery of biomarkers that can be affected by environmental pollutants, including metal(loid)s, was assessed (esterase activity, fluorescence-based oxidative stress biomarkers, metallothionein levels, glutathione-dependent enzyme activity). The research was conducted during the white stork breeding season in diverse areas (a landfill, industrial and agricultural sites, and an unpolluted area). White storks' nestlings near the landfill exhibited reduced carboxylesterase (CES) activity, elevated glutathione (GSH) concentration, as well as high Pb content in the blood. Increased As and Hg concentrations in blood were attributable to environmental contamination in agricultural area and an assumed unpolluted area, respectively. Furthermore, agricultural practices appeared to affect CES activity, as well as elevate Se levels. In addition to the successful implementation of biomarkers, present research showed that agricultural areas and a landfill are areas with increased metal(loid) levels possibly causing adverse effects on the white storks. This first-time heavy metal and metalloid analyses in the white stork nestlings from Croatia point to the necessary monitoring and future assessments of pollution impact to prevent irreversible adverse effects.

First report on the toxicity of SARS-CoV-2, alone and in combination with polyethylene microplastics in neotropical fish

The COVID-19 pandemic has caused unprecedented negative impacts in the modern era, including economic, social, and public health losses. On the other hand, the potential effects that the input of SARS-CoV-2 in the aquatic environment from sewage may represent on non-target organisms are not well known. In addition, it is not yet known whether the association of SARS-CoV-2 with other pollutants, such as microplastics (MPs), may further impact the aquatic biota. Thus, we aimed to evaluate the possible ecotoxicological effects of exposure of male adults Poecilia reticulata, for 15 days, to inactivated SARS-CoV-2 (0.742 pg/L; isolated SARS.CoV2/SP02.2020.HIAE.Br) and polyethylene MP (PE MPs) (7.1 × 10⁴ particles/L), alone and in combination, from multiple biomarkers. Our data suggest that exposure to SARS-CoV-2 induced behavioral changes (in the open field test), nephrotoxic effect (inferred by the increase in creatinine), hepatotoxic effect (inferred by the increase in bilirubin production), imbalance in the homeostasis of Fe, Ca, and Mg, as well as an anticholinesterase effect in the animals [marked by the reduction of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity]. On the other hand, exposure to PE MPs induced a genotoxic effect (assessed by the comet assay), as well as an increase in enzyme activity alpha-amylase, alkaline phosphatase, and carboxylesterases. However, we did not show synergistic, antagonistic, or additive effects caused by the combined exposure of P. reticulata to SARS-CoV-2 and PE MPs. Principal component analysis (PCA) and values from the "Integrated Biomarker Response" index indicate that exposure to SARS-CoV-2 was determinant for a more prominent effect in the evaluated animals. Therefore, our study sheds light on the ecotoxicity of the new coronavirus in non-target organisms and ratifies the need for more attention to the impacts of COVID-19 on aquatic biota.

Effects of Phenanthrene Exposure on the B-esterases Activities of Octopus maya (Voss and Solís Ramírez, 1996) Embryos

No ecotoxicological information exists on phenanthrene (Phe) exposure in cephalopods, animals of commercial and ecological importance. This study investigated the effect of Phe on two B-esterases, Acetylcholinesterase (AChE) and Carboxylesterases (CbE), in Octopus maya embryos. Octopus embryos were exposed to different treatments: control (seawater), solvent control (seawater and DMSO 0.01%), 10 and 100 µg/L of Phe. AChE and CbE activities were measured at different developmental stages (blastula, organogenesis, and growth). B-esterase activities increased in control and solvent control as the embryos developed, showing no statistically significant differences between them. On the other hand, the embryos exposed to Phe had significant differences from controls, and between the high and low concentrations. Our results indicate that B-esterases are sensitive biomarkers of exposure to Phe in O. maya. Still, complementary studies are needed to unravel the toxicodynamics of Phe and the implications of the found inhibitory effect in hatched organisms.

How will different scenarios of rising seawater temperature alter the response of marine species to lithium?

Marine ecosystems are suffering from the gradual rise in temperature due to climate change. Warming scenarios and the intensification of extreme climate events, such as marine heatwaves (MHWs), have been negatively affecting marine organisms. In addition, they are also threatened by anthropogenic pollution. Lithium (Li) is an emerging pollutant that has become a major concern due to its increasing use in a variety of applications. Understanding its influence on marine environments in combination with warming scenarios is crucial, as very little is known about its impact on marine organisms, especially when also considering the increasingly concerning impacts of climate change. With this in mind, this research aimed to assess how different scenarios of increasing temperature may affect the response of Mytilus galloprovincialis to Li. Mussels bioaccumulation levels, as well as physiological and biochemical biomarkers were analyzed after 28 days of exposure to Li under different temperature scenarios (control - 17 °C; warming - 21 °C and marine heatwave - MHW). The results indicate that mussels accumulated Li, independently of the temperature scenario. The respiration rate was higher in contaminated mussels than in the non-contaminated ones, with no differences among temperature scenarios. Furthermore, the metabolic rate decreased in non-contaminated mussels exposed to 21 °C and MHW, while mussels exposed to the combination of Li and MHW presented the highest metabolic rate. The mussels exposed to MHW and Li evidenced the highest cellular damage but Li was not neurotoxic in M. galloprovincialis. This study highlighted that MHW + Li was the most stressful condition, inducing clear negative effects in this species that can impair the growth and reproduction of an entire population. In general, the presented results highlight the importance of future studies in which it is necessary to combine the effects of pollutants and climate change scenarios, namely extreme weather events such as MHWs.

Moderate hypoxia mitigates the physiological effects of high temperature on the tropical blue crab Callinectes sapidus

Dissolved oxygen (DO) and water temperature vary in coastal environments. In tropical regions, the ability of aquatic ectotherms to cope with hypoxia and high-temperature interactive effects is fundamental for their survival. The mechanisms underlying both hypoxia and thermal tolerance are known to be interconnected, therefore, the idea of cross-tolerance between both environmental stressors has been put forward. We investigated the combined role of hypoxia and temperature changes on the physiological responses of blue crab Callinectes sapidus living in the southern Gulf of Mexico. We measured oxygen consumption, plasmatic biochemical indicators, total hemocyte count (THC), and antioxidant activity biomarkers in muscle and gill tissues of blue crab acclimated to moderate hypoxia or normoxia and exposed to a thermal fluctuation or a constant temperature, the former including a temperature beyond the optimum range. Animals recovered their routine metabolic rate (RMR) after experiencing thermal stress in normoxia, reflecting physiological plasticity to temperature changes. In hypoxia, the effect of increasing temperature was modulated as reflected in the RMR and plasmatic biochemical indicators concentration, and the THC did not suggest significant alterations in the health status. In both DO, the antioxidant defense system was active against oxidative (OX) damage to lipids and proteins. However, hypoxia was associated with an increase in the amelioration of OX damage. These results show that C. sapidus can modulate its thermal response in a stringent dependency with DO, supporting the idea of local acclimatization to tropical conditions, and providing insights into its potential as invasive species.

Gone with sunscreens: Responses of blue mussels (Mytilus edulis) to a wide concentration range of a UV filter ensulizole

Organic UV filters have emerged as a new threat to marine organisms, but ecotoxicological studies have so far focused on only a few substances despite the chemical diversity of these synthetic sunscreen agents. Here we examined the responses of blue mussels Mytilus edulis to ensulizole, a non-lipophilic UV filter commonly found in the Baltic Sea. Mussels were exposed for three weeks to five ensulizole concentrations of 10, 10², 10³, 10⁴, and 10⁵ ng/L. Stress on stress response was evaluated by subjecting mussels to air exposure. A battery of biomarkers related to detoxification and antioxidant defense, oxidative stress damage, energy reserves and metabolism, autophagy, apoptosis, inflammation, and DNA damage was measured in the gills and the digestive gland. In general, ensulizole affected the antioxidant response, energy storage, and cell death-related processes in mussel tissues. Mussels exposed to low, environmentally relevant concentrations of ensulizole had a shorter air survival time than the control. Ensulizole often showed the non-monotonic concentration-response curves, suggesting the complex effects of this UV filter at molecular, biochemical, and organismal levels.

Characterisation of plasmatic B-esterases in bottlenose dolphins (Tursiops truncatus) and their potential as biomarkers of xenobiotic chemical exposures

A total of 164 blood samples from 16 clinically healthy bottlenose dolphins (Tursiops truncatus), were obtained from an aquarium in Spain between 2019 and 2020, as part of their preventive medicine protocol. In addition to conventional haematological and biochemical analyses, plasmatic B-esterase activities were characterised to determine the potential application of such analyses in wild counterparts. The hydrolysis rates for the substrates of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and carboxylesterase (CE) activity in plasma were measured, the last using two commercial substrates, p-nitrophenyl acetate (pNPA) and p-nitrophenyl butyrate (pNPB). Activity rates (mean ± SEM in nmol/min/mL plasma) were (in descending order): AChE (125.6 ± 3.8), pNPB-CE (65.0 ± 2.2), pNPA-CE (49.7 ± 1.1) and BuChE (12.8 ± 1.3). These values for dolphins are reported in here for the first time in this species. Additionally, the in vitro sensitivity of two B-esterases (AChE and pNPB-CE) to chemicals of environmental concern was determined, and the protective role of plasmatic albumin assessed. Out of the B-esterases measured in plasma of dolphin, AChE activity was more responsive in vitro to pesticides, while CEs had a low response to plastic additives, likely due to the protective presence of albumin. However, the clear in vitro interaction of these environmental chemicals with purified AChE from electric eels and recombinant human hCEs (hCE1 and hCE2) and albumin, predicts their impact in other tissues that require in vivo validation. A relationship between esterase-like activities and health parameters in terrestrial mammals has already been established. Thus, B-esterase measures could be easily included in marine mammal health assessment protocols for dolphins as well, once the relationship between these measures and the animal's fitness has been established.

In vitro spermiotoxicity and in vivo adults' biochemical pattern after exposure of the Mediterranean mussel to the sunscreen avobenzone

Avobenzone (AVO) is one of the most frequent ultraviolet (UV) filters in personal care products (PCPs). The Mediterranean mussel Mytilus galloprovincialis is a bioindicator often used for ecotoxicological research. Since UV filters reach higher peaks during summer in aquatic bodies, coincident with mussels' spawning period, and bivalves are sessile, both male gametes and adults of this species were used in this experiment. Therefore, the present study aimed to assess how AVO affects M. galloprovincialis at different biological levels. In vitro experiments on sperms (30 min-exposure) and in vivo experiments on adults (28 days-exposure) were carried out at 0.1, 1.0 and 10.0 μg/L of AVO concentrations. The oxidative and physiological status together with genotoxicity in exposed sperms were assessed. Several biochemical parameters related to enzymatic antioxidant defences, biotransformation enzymes, cell membrane damage, energy reserves, and neurotoxicity were evaluated in adult mussels. Results of in vitro sperm exposure to AVO showed significant overproduction of superoxide anions and DNA damages in all treatments and decrease in sperm viability at 1.0 and 10.0 μg/L. AVO exposure also led to complete inhibition of motility of sperms at the highest concentration, while a significant increase of curvilinear velocity and decrease of wobble occurred at 1.0 μg/L. In vivo exposed adults exhibited a significant decrease in metabolic capacity at 0.1 μg/L, a significant increase in the total protein content and enzymatic turnover as superoxide dismutase (antioxidant defence) at 10 μg/L. This study revealed an ecological concern related to the high sensitivity of sperms respectively to adults under environmentally relevant concentrations of AVO, underpinning an hypothesis of male reproductive function impairments.

Plasmatic B-esterases as potential biomarkers of exposure to marine plastics in loggerhead turtles

Sea turtles are particularly vulnerable to plastic exposures, and the associated chemical additives, due to their feeding strategies. The species Caretta caretta is a proposed sentinel of plastic pollution worldwide. Thus, there is a need to find adequate biomarkers of plastic exposure through non-invasive protocols for this IUCN protected species. Plasmatic acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and carboxylesterase (CE) which participate in xenobiotic and endogenous metabolic reactions could all serve as biomarkers, as they are responsive to plasticizers and have already proved adequate for identifying organophosphorus esters exposures. Here we measured plasmatic B-esterases in wild specimens captured as accidental by-catch. Measurements were taken in each individual either at entry into the rehabilitation program or immediately before release after a recovery period. For CE measurements, 4 commercial substrates were used as potentially indicative of distinct enzyme isoforms. Increased activity was seen with the butyrate-derived substrates. Plasmatic CE activities were over one order of magnitude higher than AChE and BuChE substrates. Moreover, an in vitro protocol with the inclusion of plastic additives such as tetrabromobisphenol A (TBBPA), bisphenol A and some of its analogues was considered a proxy of enzymatic interactions. A clear inhibition by TBBPA was found when using commercially purified AChE and recombinant CE proteins. Overall, from in vitro and in vivo evidences, CEs in plasma are sensitive and easily measurable and have been shown to significantly increase after turtles have been rehabilitated in rescue centres. Nevertheless, the inclusion of plastic (or plasticizers) characterisation would help to confirm its association with plasmatic enzyme modifications before they can be adopted as biomarkers of plastic contamination.

Polyphagous insect Olepa sps. feeding on cardenolide rich Calotropis gigantea (L.) leaves and detoxification mechanism involving GST

Cardenolides, a group of cardiac glycosides are potent inhibitors of Na⁺/K⁺ ATPase pump in mammals, animals including insects. Some insects can circumvent the toxicity of cardenolides by mechanisms like target site resistance and metabolic resistance resulting in enhanced tolerance or adaptation. In this paper, we report an intriguing observation of a polyphagous feeder feeding gregariously on the leaves of Calotropis gigantea (L.) without any apparent adverse effect. No choice feeding assay showed higher larval biomass and reduced number of days to develop on C. gigantea leaves compared to Ricinus and banana. We found the activity of GST higher in C. gigantea fed larva and HR LC-MS analysis of Olepa sps. revealed the presence of glutathione-strophanthidin conjugate in larval body tissue. In silico molecular simulation results confirmed strong interaction between delta variant GST and glutathione-strophanthidin complex. The sequestration site and cost benefit of glutathione-strophanthidin sequestration in body tissues of Olepa sps. needs further investigation.

Biochemical alterations caused by lanthanum and gadolinium in Mytilus galloprovincialis after exposure and recovery periods

The increasing use of rare earth elements (REEs) in electric and electronic equipment has been associated with the presence of these elements in aquatic systems. The present study aimed to evaluate the toxicity of two REEs, Lanthanum (La) and Gadolinium (Gd), towards the mussel species Mytilus galloprovincialis. For this, the toxicity was assessed after a short-term exposure (14 days) to an environmentally relevant concentration of each element (10 μg/L), followed by a recovery period (14 days) in the absence of any contaminant. The measured biomarkers included energy-related parameters, activity of antioxidant and biotransformation enzymes, indicators of oxidative damage, levels of oxidized glutathione and neurotoxicity. After exposure mussels accumulated more La (0.54 μg/g) than Gd (0.15 μg/g). After recovery higher concentration decrease was observed for Gd (≈40% loss) compared to La exposed mussels (≈30% loss) which may be associated with lower detoxification capacity of mussels previously exposed to La. Mussels increased their metabolism (i.e., higher electron transport system activity) only after the exposure to Gd. Exposure to La and Gd resulted into lower energy expenditure, while when both elements were removed glycogen and protein concentrations decreased to values observed in non-contaminated mussels. Antioxidant and biotransformation capacity was mainly increased in the presence of Gd. This defense response avoided the occurrence of cellular damage but still loss of redox balance was found regardless the contaminant, which was re-established after the recovery period. Neurotoxicity was only observed in the presence of Gd with no effects after the recovery period. Results showed that a short-term exposure to La and especially to Gd can exert deleterious effects that may compromise specific biochemical pathways in aquatic species, such as M. galloprovincialis, but under low concentrations organisms can be able to re-establish their biochemical status to control levels after a recovery period.

B-esterases characterisation in the digestive tract of the common octopus and the European cuttlefish and their in vitro responses to contaminants of environmental concern

Cephalopods are a group of marine invertebrates that have received little attention as sentinel species in comparison to other molluscs, such as bivalves. Consequently, their physiological and biochemical xenobiotic metabolism responses are poorly understood. Here we undertake a comparative analysis of the enzymatic activities involved in detoxification reactions and neural transmission in the digestive tract of two commercial cephalopods: the Common octopus, Octopus vulgaris, and the European cuttlefish, Sepia officinalis. For methodological purposes, several common B-esterases (five carboxylesterase (CE) substrates and three cholinesterase (ChE) determinations) were assayed as a proxy of metabolic and neuronal activities, respectively. Four components of the digestive tract in each species were considered: salivary glands, the stomach, the digestive gland and the caecum. The in vitro responses of digestive gland homogenates to model chemicals and contaminants of environmental concern were contrasted between both cephalopod species. The baseline biochemical activities in the four digestive tract components were also determined. Moreover, in order to validate the protocol, purified proteins, recombinant human CE (CE1 and CE2) and purified eel acetylcholinesterase (AChE) were included in the analysis. Overall, carboxylesterase activities were higher in octopus than in cuttlefish, with the activity quantified in the digestive tract components in the following order: digestive gland ≈ caecum > stomach ≈ salivary glands, with higher hydrolysis rates reached with naphthyl-derived substrates. In contrast, cuttlefish hydrolysis rates with ChE substrates were higher than in octopus. This trend was also reflected in a higher sensitivity to CE inhibitors in octopus and to AChE inhibitors in cuttlefish. Given the detoxification character of CEs and its protective role preventing AChE inhibition, octopus could be regarded as more efficiently protected than cuttlefish from neurotoxic exposures. A full characterisation of B-esterases in the digestive tract of the two common cephalopods is also provided.

Blood biomarkers in white stork (Ciconia ciconia) nestlings show different responses in several areas of Croatia

White stork nestlings can provide quantitative data on the quality of the environment, as they are dependent on their parents that provide locally foraged food. Blood was sampled from the brachial vein (n = 109) and the sampling was performed in parallel with ringing during breeding season 2020 from five areas in eastern Croatia: Lonjsko polje, Jelas polje, Slavonski Brod-east, Podunavlje, and Donje Podravlje. In the present study, for the first time in Croatia, the following enzymatic biomarkers were assessed in white stork nestlings: activities of acetylcholinesterase (AChE), carboxylesterase (CES), glutathione S-transferase (GST), and glutathione reductase (GR), as well as nonenzymatic biomarkers: levels of glutathione (GSH) and reactive oxygen species (ROS). All endpoints were measured in two blood fractions: plasma and a postmitochondrial fraction (S9). Nestlings from Podunavlje and Donje Podravlje, areas known for intensive agriculture, showed lower AChE and CES activity when compared to the other investigated areas, indicating the presence of inhibitory xenobiotics. Higher oxidative stress was observed in Slavonski Brod-east, an area surrounded by metal and engineering industry, and Podunavlje compared to the other sampling areas. Hence, this study shows the impact of pollutants from the surrounding metal, petroleum, and agricultural industry might have on the biomarkers in white stork nestlings, which are often seen as early-warning signals.

Two types of microplastics (polystyrene-HBCD and car tire abrasion) affect oxidative stress-related biomarkers in earthworm Eisenia andrei in a time-dependent manner

Microplastics are small plastic fragments that are widely distributed in marine and terrestrial environments. While the soil ecosystem represents a large reservoir for plastic, research so far has focused mainly on the impact on aquatic ecosystems and there is a lack of information on the potentially adverse effects of microplastics on soil biota. Earthworms are key organisms of the soil ecosystem and are due to their crucial role in soil quality and fertility a suitable and popular model organism in soil ecotoxicology. Therefore, the aim of this study was to gain insight into the effects of environmentally relevant concentrations of microplastics on the earthworm Eisenia andrei on multiple levels of biological organization after different exposure periods. Earthworms were exposed to two types of microplastics: (1) polystyrene-HBCD and (2) car tire abrasion in natural soil for 2, 7, 14 and 28d. Acute and chronic toxicity and all subcellular investigations were conducted for all exposure times, avoidance behavior assessed after 48 h and reproduction after 28d. Subcellular endpoints included enzymatic biomarker responses, namely, carboxylesterase, glutathione peroxidase, acetylcholinesterase, glutathione reductase, glutathione S-transferase and catalase activities, as well as fluorescence-based measurements of oxidative stress-related markers and multixenobiotic resistance activity. Multiple biomarkers showed significant changes in activity, but a recovery of most enzymatic activities could be observed after 28d. Overall, only minor effects could be observed on a subcellular level, showing that in this exposure scenario with environmentally relevant concentrations based on German pollution levels the threat to soil biota is minimal. However, in areas with higher concentrations of microplastics in the environment, these results can be interpreted as an early warning signal for more adverse effects. In conclusion, these findings provide new insights regarding the ecotoxicological effects of environmentally relevant concentrations of microplastics on soil organisms.

Metal nanoparticles functionalized with nutraceutical Kaempferitrin from edible Crotalaria juncea, exert potent antimicrobial and antibiofilm effects against Methicillin-resistant Staphylococcus aureus

Kaempferitrin (KF), a flavonol glycoside, was isolated from the edible plant Crotalaria juncea. Optimization for the synthesis of silver (AgNPs) and copper (CuNPs) nanoparticles using C. juncea extract and kaempferitrin were attempted for the first time. A detailed study on size and stability analysis have been reported. Efficacy of KF@AgNPs and KF@CuNPs against biofilm formation and planktonic mode of growth on methicillin-resistant Staphylococcus aureus (MRSA) along with possible mechanisms has been explored. Release of Cu(II) upon prolonged treatment with KF@CuNPs in the presence of MRSA was quantified through Alizarin red test, indicating the antibacterial effect is initiated by the CuNPs itself. Time kill curve depicted both the NPs have similar kill kinetics to curtail the pathogen and imaging with Crystal violet assay, Fluorescent live dead imaging and SEM analysis revealed a 60% reduction in biofilm formation at the Sub-MIC concentration of KF@AgNPs and KF@CuNPs. Furthermore, the membrane permeability and cell surface hydrophobicity were altered in the presence of both the NPs. The colony count from the in vivo infection zebrafish model in the treatment group showed a decline of > 1.8 fold for KF@AgNPs and > two fold for KF@CuNPs. Toxicity studies did not reveal any abnormality in liver and brain enzyme levels. Liver morphology images show no severe cytological alterations when treated with KF@AgNPs and were almost similar to the normal liver. Thus, KF@AgNPs was nontoxic and caused significant reduction in biofilm formation in MRSA, also reduced bacterial bioburden in the infected zebrafish, which has the potential to be explored in higher animal models.

Behavioral, physiological and biochemical responses and differential gene expression in Mytilus galloprovincialis exposed to 17 alpha-ethinylestradiol and sodium lauryl sulfate

Mixture of contaminants often determine biological responses of marine species, making difficult the interpretation of toxicological data. The pharmaceutical 17 alpha-ethinylestradiol (EE2) and the surfactant Sodium Lauryl Sulfate (SLS) commonly co-occur in the marine environment. This study evaluated the effects of EE2 (125.0 ng/L) and SLS (4 mg/L), acting individually and combined, in the mussel Mytilus galloprovincialis. Contaminated mussels closed their valves for longer periods than control ones, especially in the presence of both contaminants, with longer closure periods immediately after spiking compared to values obtained one day after spiking. Nevertheless, males and females increased their metabolism when in the presence of both contaminants (males) and SLS (females), and independently on the treatment males and females were able to activate their antioxidant and biotransformation defences. Although enhancing defences mussels still presented cellular damage and loss of redox balance, especially noticed in the presence of EE2 for males and SLS for females. Histopathological damage was found at mussel's gills in single and mixture exposure, and qPCR analysis revealed a clear estrogen receptor expression with no additive effect due to combined stressors. The results obtained highlight the harmful capacity of both contaminants but further research on this matter is needed, namely considering different climate change scenarios.

Assessment of the impact of aquaculture facilities on transplanted mussels (Mytilus galloprovincialis): Integrating plasticizers and physiological analyses as a biomonitoring strategy

The growing plastic production and its continuous use is a significant problem. In addition, aquaculture practices have experienced a considerable growth and plastic is widely used in these activities, hence plasticizers must be considered due to their potential ecotoxicological impacts on species. Mussels placed inside an Integrated Multi-Trophic Aquaculture (IMTA) system and at two control locations were employed to quantify the ingestion of anthropogenic particles and associated chemical plasticizers, such as bisphenol A (BPA) jointly to bisphenol F (BPF) and bisphenol S (BPS), and phthalates represented by diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). In addition, some metabolism and oxidative stress related parameters were measured in mussels' whole soft tissue. Anthropogenic particle ingestion of mussels increased over time at the three locations and the following order of abundance of pollutants was observed: BPA> BPF> DEHP> DBP> BPS> DEP. Even though no differences according to location were found for pollutants' occurrence, time trends were evidenced for BPA and DEHP. On the other hand, a location effect was observed for biomarkers with highest values detected in mussels located at the vicinities of the aquaculture facility. In addition, a reduced detoxification activity was observed over time parallel to BPA decrease.

Application of Non-Destructive Methods: Biomarker Assays in Blood of White Stork (Ciconia ciconia) Nestlings

White stork (Ciconia ciconia) nestlings can provide quantitative information on the quality of the surrounding environment by indicating the presence of pollutants, as they depend on locally foraged food. This study represents the first comparison of biomarkers in two fractions of white stork nestling blood: plasma and S9 (the post-mitochondrial fraction). The aim of this study was to evaluate acetylcholinesterase (AChE), carboxylesterase (CES), glutathione S-transferase (GST), and glutathione reductase (GR), as well as to establish a novel fluorescence-based method for glutathione (GSH) and reactive oxygen species (ROS) detection in plasma and S9. Considering the enzymatic biomarkers, lower variability in plasma was detected only for AChE, as CES, GST, and GR had lower variability in S9. Enzyme activity was higher in plasma for AChE, CES, and GST, while GR had higher activity in S9. Regarding the fluorescence-based method, lower variability was detected in plasma for GSH and ROS, although higher GSH detection was reported in S9, and higher ROS was detected in plasma. The present study indicated valuable differences by successfully establishing protocols for biomarker measurement in plasma and S9 based on variability, enzyme activity, and fluorescence. For a better understanding of the environmental effects on nestlings' physiological condition, biomarkers can be measured in plasma and S9.

Biomarker responses in earthworm coelomocyte extract - Noninvasively collected sample for pesticide effect assessment

Earthworms are often used as model organisms in ecotoxicological research because of their natural habitat where they can be exposed to many different pollutants, including pesticides. Since a number of them has to be sacrificed for sample collection, it would be useful to develop non-invasive methods and techniques suitable for the analysis of target parameters. The aim of this study is to determine whether the coelomocyte extract, obtained by the non-invasive method, can be used to measure responses of biochemical biomarkers and to establish if it can be used in assessing the effects of pesticides already known to have a negative impact on the earthworms. In the present study Eisenia andrei earthworms were exposed for 48 h to organophosphates dimethoate and pirimiphos-methyl using the filter paper contact test. Following exposure, coelomocyte extracts were prepared and acetylcholinesterase (AChE) and carboxylesterase (CES) activities were measured. The percentage of inhibition of the measured enzymes in the coelomocyte extract was compared with the inhibition of the same enzyme activities in the samples obtained from the whole body homogenate. AChE and CES inhibition was observed at all concentrations for both pesticides in different types of samples. Compared to the coelomocyte extract, the level of AChE inhibition was slightly stronger in the whole body homogenate. Inhibition of CES at the same concentrations in different types of samples did not always coincide, especially in the case of dimethoate, however significant inhibition of CES in coelomocyte extract was recorded. This study indicates the possibility of using the coelomocyte extract for measurement of biochemical biomarkers and assessment of pesticide effects.

Maturation trade-offs in octopus females and their progeny: energy, digestion and defence indicators

Sexual maturation and reproduction influence the status of a number of physiological processes and consequently the ecology and behaviour of cephalopods. Using Octopus mimus as a study model, the present work was focused in the changes in biochemical compound and activity that take place during gonadal maturation of females and its consequences in embryo and hatchlings characteristics. To do that, a total of 31 adult females of O. mimus were sampled to follow metabolites (ovaries and digestive gland) and digestive enzyme activities (alkaline and acidic proteases) during physiological and functional maturation. Levels of protein (Prot), triacylglyceride (TG), cholesterol (Chol), glucose (Glu), and glycogen (Gly) were evaluated. Groups of eggs coming from mature females were also sampled along development and after hatching (paralarvae of 1 and 3 days old) to track metabolites (Prot, TG, Glu, Gly, TG, Chol), digestive enzymes activity (Lipase, alkaline proteases, and acidic proteases), and antioxidant/detoxification defence indicators with embryos development. Based on the data obtained, we hypothesized that immature females store Chol in their ovaries, probably from the food they ingested, but switch to TG reserves at the beginning of the maturation processes. At the same time, results suggest that these processes were energetically supported by Glu, obtained probably from Gly breakdown by gluconeogenic pathways. Also, was observed that embryos metabolites and enzyme activities (digestive and antioxidant/detoxification enzymes) where maintained without significant changes and in a low activity during the whole organogenesis, meaning that organogenesis is relatively not energetically costly. In contrast, after organogenesis, a mobilization of nutrients and activation of the metabolic and digestive enzymes was observed, together with increments in consumption of yolk and Gly, and reduction in lipid peroxidation. Derived from our results, we also have the hypothesis that reactive oxygen species (ROS) were produced during the metabolic processes that occurs in ovarian maturation. Those ROS may be in part transferred to the egg provoking a ROS charge to the embryos. The elimination of ROS in embryos started when the activity of the heart and the absorption of the yolk around stages XIV and XV were evident. Altogether, these processes allowed the paralarvae to hatch with buffered levels of ROS and with the antioxidant defence mechanisms ready to support further ROS production derived from paralarvae higher life stage requirements (feeding and metabolic demands).

Behavioral, molecular and physiological responses of embryo-larval zebrafish exposed to types I and II pyrethroids

Pyrethroids are potent neurotoxicants that may elicit multiple pathways of toxicity in non-target organisms. Comparative studies on the mechanistic and developmental effects of types I and II pyrethroids against non-target aquatic species are limited. This study assessed the effects of the two pyrethroid types against embryo-larval zebrafish (Danio rerio) at environmentally relevant and laboratory concentrations. Zebrafish embryos were exposed to type-I (permethrin, bifenthrin) and type-II (deltamethrin, λ-cyhalothrin, fenvalerate, esfenvalerate) pyrethroids at 1000, 10, 0.1, 0.01, 0.0 μg/L, starting at 5-h post-fertilization (hpf) through 5-d post-fertilization (dpf) under static exposure conditions. Swimming behavior (distance traveled and velocity) was assessed at 5-dpf. The relative expression of Nrf2a, GST, Casp-9 and p53 mRNA transcripts, carboxyl esterase (CES) activity and total reactive oxygen species (ROS) were measured. The stability of the pyrethroids across 5 days was analyzed. Bifenthrin-(10 μg/L) and esfenvalerate-(1000 μg/L) significantly (p < 0.05) reduced total distance traveled by larvae while 1000 μg/L deltamethrin and λ-cyhalothrin were lethal causing body axis curvature and pericardial edema. At environmentally relevant concentrations-(μg/L) compared to control, permethrin-(0.122) upregulated Nrf2a and Casp-9 expressions while λ-cyhalothrin-(0.053) downregulated Nrf2a and fenvalerate-0.037 downregulated GST. At laboratory concentrations-(μg/L), permethrin-(1000) upregulated Nrf2a, Casp-9 and p53 expressions, bifenthrin-(10) upregulated Casp-9 while fenvalerate-(0.1) and esfenvalerate-(1000) downregulated GST. There was concentration dependent increase in CES activity which correlated positively with total ROS. Pyrethroid concentrations decreased significantly by day 5. This study showed disparity in the mechanistic effects across the pyrethroids types and their instability in aqueous media may underestimate toxicity against non-target aquatic species when exposed in their natural environment.

An in vitro screening with emerging contaminants reveals inhibition of carboxylesterase activity in aquatic organisms

Pharmaceuticals and personal care products (PPCPs) form part of the new generation of pollutants present in many freshwater and marine ecosystems. Although environmental concentrations of these bioactive substances are low, they cause sublethal effects (e.g., enzyme inhibition) in non-target organisms. However, little is known on metabolism of PPCPs by non-mammal species. Herein, an in vitro enzyme trial was performed to explore sensitivity of carboxylesterase (CE) activity of aquatic organisms to fourteen PPCPs. The esterase activity was determined in the liver of Mediterranean freshwater fish (Barbus meridionalis and Squalius laietanus), coastal marine fish (Dicentrarchus labrax and Solea solea), middle-slope fish (Trachyrhynchus scabrus), deep-sea fish (Alepocephalus rostratus and Cataetix laticeps), and in the digestive gland of a decapod crustacean (Aristeus antennatus). Results showed that 100μM of the lipid regulators simvastatin and fenofibrate significantly inhibited (30-80% of controls) the CE activity of all target species. Among the personal care products, nonylphenol and triclosan were strong esterase inhibitors in most species (36-68% of controls). Comparison with literature data suggests that fish CE activity is as sensitive to inhibition by some PPCPs as that of mammals, although their basal activity levels are lower than in mammals. Pending further studies on the interaction between PPCPs and CE activity, we postulate that this enzyme may act as a molecular sink for certain PPCPs in a comparable way than that described for the organophosphorus pesticides.

Hepatic biotransformation and antioxidant enzyme activities in Mediterranean fish from different habitat depths

Marine fish are threatened by anthropogenic chemical discharges. However, knowledge on adverse effects on deep-sea fish or their detoxification capabilities is limited. Herein, we compared the basal activities of selected hepatic detoxification enzymes in several species (Solea solea, Dicentrarchus labrax, Trachyrhynchus scabrus, Mora moro, Cataetix laticeps and Alepocehalus rostratus) collected from the coast, middle and lower slopes of the Blanes Canyon region (Catalan continental margin, NW Mediterranean Sea). The xenobiotic-detoxifying enzymes analysed were the phase-I carboxylesterases (CbEs), and the phase-II conjugation activities uridine diphosphate glucuronyltransferase (UDPGT) and glutathione S-transferase (GST). Moreover, some antioxidant enzyme activities, i.e., catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR), were also included in this comparative study. Because CbE activity is represented by multiple isoforms, the substrates α-naphthyl acetate (αNA) and ρ-nitrophenyl acetate (ρNPA) were used in the enzyme assays, and in vitro inhibition kinetics with dichlorvos were performed to compare interspecific CbE sensitivity. Activity of xenobiotic detoxification enzymes varied among the species, following a trend with habitat depth and body size. Thus, UDPGT and some antioxidant enzyme activities decreased in fish inhabiting lower slopes of deep-sea, whereas UDPGT and αNA-CbE activities were negatively related to fish size. A trend between CbE activities and the IC50 values for dichlorvos suggested S. solea and M. moro as potentially more sensitive to anticholinesterasic pesticides, and T. scabrus as the most resistant one. A principal component analysis considering all enzyme activities clearly identified the species but this grouping was not related to habitat depth or phylogeny. Although these results can be taken as baseline levels of the main xenobiotic detoxification enzymes in Mediterranean fish, further research is needed to evaluate their response to environmental contaminant exposure.

Effects of selected xenobiotics on hepatic and plasmatic biomarkers in juveniles of Solea senegalensis

In recent years, Solea senegalensis has increasingly been used in pollution monitoring studies. In order to assess its response to some particular widespread pollutants, juveniles of S. senegalensis were administered an intraperitoneal injection of the model aryl hydrocarbon receptor agonist β-naphtoflavone (βNF) and chemicals of environmental concern, such as the fungicide ketoconazole (KETO), the lipid regulator gemfibrozil (GEM), the surfactant nonylphenol (NP) and the synthetic hormone ethinylestradiol (EE2). Two days after injection, the effect of these chemicals was followed up as alterations of hepatic microsomal activities of the cytochrome P450 (CYPs) and associated reductases, carboxylesterases (CbEs) and the conjugation enzyme uridine diphosphate glucuronyltransferase (UDPGT). In the cytosolic fraction of the liver, the effect on CbEs, glutathione S-transferase (GST) and antioxidant activities was also considered. Alterations on the endocrine reproductive system were evaluated by plasma levels of vitellogenin (VTG) and the sex steroids estradiol (E2), testosterone (T), 11-ketotestosterone (11KT) and the progestin 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P). Injection with the model compound βNF induced the hydrolysis rate of the seven CYP substrates assayed. The xenobiotic GEM induced three CYP-related activities (e.g. ECOD) and UDPGT, but depressed antioxidant defenses. EE2 induced four CYPs, more significantly ECOD and BFCOD activities. The xenoestrogens NP and EE2 altered the activities of CbE in microsomes and catalase, and were the only treatments that induced de novo VTG synthesis. In addition, the progestin 17,20β-P, was induced in NP-injected fish. None of the treatments caused statistically significant effects on steroid plasma levels. In conclusion, the CYP substrates assayed responded specifically to treatments and juveniles of S. senegalensis appear good candidates for assessing xenobiotics exposure.

Application of microcosmic system for assessment of insecticide effects on biomarker responses in ecologically different earthworm species

Earthworms from different ecological categories--epigeic Eisenia andrei and Lumbricus rubellus, endogeic Octolasion lacteum and anecic Lumbricus terrestris--were exposed in a microcosmic system to three commonly used insecticides. The effects of the insecticides were evaluated by measuring the following molecular biomarkers-the activities of AChE, CES, CAT, GST and the concentration of GSH. The results showed that environmentally relevant doses of organophosphates dimethoate and pirimiphos-methyl significantly affected the measured biomarkers, whereas pyrethroid deltamethrin did not affect the earthworms at the recommended agricultural dose. Considering the ecological category of earthworms, the results were inhomogeneous and species-specific differences in the biomarker responses were recorded. Since the biomarker responses of the investigated earthworm species were different after exposure to organophosphates in a microcosm compared to the exposure via standardized toxicity tests, two types of species sensitivity should be distinguished-physiological and environmental sensitivity. In addition, the hormetic effect of organophosphates on AChE and CES activities was recorded. The detection of hormesis in a microcosm is of great importance for future environmental research and soil biomonitoring, since in a realistic environment pollutants usually occur at low concentrations that could cause a hormetic effect. The results demonstrate the importance of the application of microcosmic systems in the assessment of the effects of environmental pollutants and the necessity of taking into account the possible differences between physiological and environmental species sensitivity.

Multiple resistances and complex mechanisms of Anopheles sinensis mosquito: a major obstacle to mosquito-borne diseases control and elimination in China

Malaria, dengue fever, and filariasis are three of the most common mosquito-borne diseases worldwide. Malaria and lymphatic filariasis can occur as concomitant human infections while also sharing common mosquito vectors. The overall prevalence and health significance of malaria and filariasis have made them top priorities for global elimination and control programmes. Pyrethroid resistance in anopheline mosquito vectors represents a highly significant problem to malaria control worldwide. Several methods have been proposed to mitigate insecticide resistance, including rotational use of insecticides with different modes of action. Anopheles sinensis, an important malaria and filariasis vector in Southeast Asia, represents an interesting mosquito species for examining the consequences of long-term insecticide rotation use on resistance. We examined insecticide resistance in two An. Sinensis populations from central and southern China against pyrethroids, organochlorines, organophosphates, and carbamates, which are the major classes of insecticides recommended for indoor residual spray. We found that the mosquito populations were highly resistant to the four classes of insecticides. High frequency of kdr mutation was revealed in the central population, whereas no kdr mutation was detected in the southern population. The frequency of G119S mutation in the ace-1 gene was moderate in both populations. The classification and regression trees (CART) statistical analysis found that metabolic detoxification was the most important resistance mechanism, whereas target site insensitivity of L1014 kdr mutation played a less important role. Our results indicate that metabolic detoxification was the dominant mechanism of resistance compared to target site insensitivity, and suggests that long-term rotational use of various insecticides has led An. sinensis to evolve a high insecticide resistance. This study highlights the complex network of mechanisms conferring multiple resistances to chemical insecticides in mosquito vectors and it has important implication for designing and implementing vector resistance management strategies.