Biomarkers In Fish Research Articles

Fish biomarker responses to perturbation by drought in streams

ABSTRACT Drought can be viewd as a perturbation in running waters and fish are often trapped in isolated pools, where deterioration of water quality may be stressful. We investigated how this extreme condition influences response of oxidative stress biomarkers. The response of the characid Astyanax elachylepis was assessed during the dry and rainy seasons in intermittent and perennial (control) sites in streams from Brazilian savannah (Cerrado). We predicted that the biomarkers would be enhanced in the dry season in intermittent streams only due the environmentally harsh conditions in the few isolated pools that remain filled with water. As predicted, fish from the intermittent stream in the dry season presented higher gill MDA values, indicating greater stress. In the liver, MDA values were higher in the dry season for both intermittent and perennial streams, suggesting a generalized seasonal response. As expected, some antioxidant response enzymes changed in the intermittent sites during the dry season. Therefore, oxidative stress biomarkers vary seasonally, with greater increase in intermittent sites. These evidences contribute for the understanding of the spatio-temporal variation of the fish responses and fish resistance to perturbations by drought in tropical environments.

Ecotoxicological effects of microplastics and adsorbed contaminants on aquatic organisms

Microplastic (< 5 mm) pollution have raised concern on behalf of the scientific community and the general public. Microplastic occurrence in aquatic environments and organisms have been well documented. However, it is in recent years that the ecotoxicological effects of microplastics have begun to be studied. The aim of the present study was to review, evaluate and discuss the current state of art regarding microplastic and related contaminants ecotoxicological effects in microalgae, crustaceans, molluscs and fish. The results of previous studies have proven growth inhibition and chlorophyll-a decrease in microalgae. Ingestion by small crustaceans and population reduction have been evidenced. Biomarkers in bivalves and fish have shown neurotoxic effects and oxidative stress, along with abnormal behavior. The current state of art lacks realistic parameters and microplastic concentrations to assess environmental pollution. The need for further research was discussed.

Associations of plasma, RBCs, and hair carbon and nitrogen isotope ratios with fish, meat, and sugar-sweetened beverage intake in a 12-wk inpatient feeding study

Naturally occurring carbon and nitrogen stable isotope ratios [13C/12C (CIR) and 15N/14N (NIR)] are promising dietary biomarkers. As these candidate biomarkers have long tissue residence times, long-term feeding studies are needed for their evaluation. Our aim was to evaluate plasma, RBCs, and hair CIR and NIR as biomarkers of fish, meat, and sugar-sweetened beverage (SSB) intake in a 12-wk dietary intervention. Thirty-two men (aged 46.2±10.5 y; BMI: 27.2±4.0 kg/m2) underwent a 12-wk inpatient dietary intervention at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) in Phoenix, Arizona. The effects of fish, meat, and SSB intake on CIR and NIR were evaluated using a balanced factorial design, with each intake factor at 2 levels (present/absent) in a common, background diet (50% carbohydrate, 30% fat, 20% protein). Fasting blood samples were taken biweekly from baseline, and hair samples were collected at baseline and postintervention. Data were analyzed using multivariable regression. The postintervention CIR of plasma was elevated when diets included meat (β=0.89, 95% CI: 0.73,1.05) and SSBs (β=0.48, 95% CI: 0.32, 0.64). The postintervention NIR of plasma was elevated when diets included fish (β=0.85, 95% CI: 0.64, 1.05) and meat (β=0.61, 95% CI: 0.42, 0.8). Results were similar for RBCs and hair. Postintervention RBC CIR and NIR had strong associations with baseline, suggesting that turnover to the intervention diets was incomplete after 12 wk. Estimates of isotopic turnover rate further confirmed incomplete turnover of RBCs. CIR was associated with meat and SSBs, and more strongly with meat. NIR was associated with fish and meat, and more strongly with fish. Overall, CIR and NIR discriminated between dietary fish and meat, and to a lesser extent SSBs, indicating their potential utility as biomarkers of intake in US diets. Approaches to make these biomarkers more specific are needed. This trial was registered at clinicaltrials.gov as NCT01237093.

Metalloproteomic approach of mercury-binding proteins in liver and kidney tissues of Plagioscion squamosissimus (corvina) and Colossoma macropomum (tambaqui) from Amazon region: Possible identification of mercury contamination biomarkers

Fish is an important source of protein, vitamins, and minerals. However, this food is also a major source of human exposure to toxic contaminants such as mercury. Thus, this paper aimed to evaluate mercury-binding proteins for possible application as biomarkers of mercury contamination in hepatic and renal tissues of Plagioscion squamosissimus (carnivorous fish) and Colossoma macropomum (omnivorous fish) from the Amazon region using metalloproteomic approach. The proteome of hepatic and renal tissues of fish species was separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and the mercury concentrations in protein spots were determined by graphite furnace atomic absorption spectrometry (GFAAS). Finally, the protein spots associated to mercury were characterized by electrospray ionization mass spectrometry (ESI-MS/MS). The activity of antioxidant enzymes (SOD, CAT, GPx, and GST) and lipid peroxidation (LPO) were also determined. The results showed that the highest concentrations of mercury were found in the carnivorous species (P. squamosissimus) and that the accumulation pattern of this metal was higher in hepatic tissues than in renal tissues for both species. A tendency was observed for greater enzymatic activity in the hepatic and renal tissues of P. squamosissimus, the species with the highest concentration of mercury. Only GPx activity in the kidney and GST in the liver were lower for the P. squamosissimus species, and this finding can be explained by the interaction of mercury with these enzymes. The data obtained by ESI-MS/MS allowed for the characterization of the protein spots associated to mercury, revealing proteins involved in energy metabolism, biomolecules transport, protein synthesis and degradation, cell differentiation, gene regulation, and the antioxidant system. The results obtained in the present study can contribute to understanding the physiological processes underlying mercury toxicity and have provided new perspectives on possible candidates for mercury contamination biomarkers in fish.

Identifying adverse outcome pathways (AOP) for Amsterdam city fish by integrated field monitoring

The European City Fish project aimed to develop a generic methodology for ecological risk assessment for urban rivers. Since traditional methods only consider a small fraction of substances present in the water cycle, biological effect monitoring is required for a more reliable assessment of the pollution status. A major challenge for environmental risk assessment (ERA) is the application of adverse outcome pathways (AOP), i.e. the linking of pollutant exposure via early molecular and biochemical changes to physiological effects and, ultimately, effects on populations and ecosystems.We investigated the linkage between responses at these different levels. Many AOP aspects were investigated, from external and internal exposure to different classes of micropollutants, via molecular key events (MKE) the impacts on organs and organisms (fish physiology), to changes in the population dynamics of fish. Risk assessment procedures were evaluated by comparing environmental quality standards, bioassay responses, biomarkers in caged and feral fish, and the impact on fish populations. Although no complete AOP was observed, indirect relationships linking pollutant exposure via MKE to impaired locomotion were demonstrated at the most polluted site near a landfill for chemical waste. The pathway indicated that several upstream key events requiring energy for stress responses and toxic defence are likely to converge at a single common MKE: increased metabolic demands. Both fish biomarkers and the bioanalytical SIMONI strategy are valuable indicators for micropollutant risks to fish communities.

Towards Non-Invasive Methods in Measuring Fish Welfare: The Measurement of Cortisol Concentrations in Fish Skin Mucus as a Biomarker of Habitat Quality.

Simple SummaryThe analysis of circulating cortisol has been by far the most common method used as a means to assess fish stress responses and, thus, animal welfare. To avoid many of the drawbacks inherent to blood sampling, cortisol can be less-invasively detected in fish skin mucus. The measurement of cortisol in skin mucus however, has, to date, only been demonstrated as suitable for farm fish, although its application to free-ranging animals would offer many advantages. The present study was therefore designed to evaluate the applicability of skin mucus cortisol analysis as a potential tool to assess habitat quality. To that end, wild fish residing in environments of different habitat quality were sampled for blood and skin mucus. First, several physiological endpoints typically used as indicators of exposure to pollutants were accurately related to the habitat quality in the Catalan chub (Squalius laietanus). Second, cortisol levels in blood were also compared between habitats, and they were successfully correlated to skin mucus cortisol concentrations. Finally, we contrasted the patterns of response of all the endpoints assessed to skin mucus cortisol levels across the sites. The strong linkages detected in this study provide new evidence that the measurement of cortisol in skin mucus could be potentially used as a biomarker of habitat quality in freshwater fish. Cortisol levels in fish skin mucus have shown to be good stress indicators in farm fish exposed to different stressors. Its applicability in free-ranging animals subject to long-term environmental stressors though remains to be explored. The present study was therefore designed to examine whether skin mucus cortisol levels from a wild freshwater fish (Catalan chub, Squalius laietanus) are affected by the habitat quality. Several well-established hematological parameters and cortisol concentrations were measured in blood and compared to variations in skin mucus cortisol values across three habitats with different pollution gradient. Fluctuations of cortisol in skin mucus varied across the streams of differing habitat quality, following a similar pattern of response to that detected by the assessment of cortisol levels in blood and the hematological parameters. Furthermore, there was a close relationship between cortisol concentrations in skin mucus and several of the erythrocytic alterations and the relative proportion of neutrophils to lymphocytes. Taken together, results of this study provide the first evidence that skin mucus cortisol levels could be influenced by habitat quality. Although results should be interpreted with caution, because a small sample size was collected in one studied habitat, the measurement of cortisol in skin mucus could be potentially used as a biomarker in freshwater fish.

Principles of problem-based learning for training and professional practice in ecotoxicology

Problem-based learning (PBL) is a protagonist of constructivism widely used successfully in higher education. PBL is a learner-centered instructional and curricular approach that can use real problems for the development of the teaching and learning process. On the other hand, the complexity of knowledge of Ecotoxicology, as well as the importance of this field for Environmental Health and society demand reflections and proposals for the training of professionals who work in this field. Therefore, in accordance with the principles of PBL, this strategy can effectively contribute to the training and professional practice of ecotoxicologists. We report herein the importance of the principles of PBL for the training of ecotoxicologists, including the discussion of a case study using fish biomarkers for the development of this teaching strategy. Teaching ecotoxicology through PBL principles allowed students to develop several advantages for Ecotoxicology training through the discussion of an authentic, real life problem that engaged them in its discussion, functioning as a stimulus for learning. The students were able to develop laboratory skills, group work competences, understand basic concepts and fundamentals of Ecotoxicology and become empowered regarding skills and competences for future practice.

Effects of industrial pollution on the reproductive biology of Squalius laietanus (Actinopterygii, Cyprinidae) in a Mediterranean stream (NE Iberian Peninsula).

Mediterranean rivers are severely affected by pollutants from industry, agriculture and urban activities. In this study, we examined how industrial pollutants, many of them known to act as endocrine disruptors (EDCs), could disturb the reproduction of the Catalan chub (Squalius laietanus). The survey was conducted throughout the reproductive period of S. laietanus (from March to July 2014) downstream an industrial WWTP located in the River Ripoll (NE Iberian Peninsula). Eighty fish (28 females and 52 males) were caught by electrofishing upstream and 77 fish (33 females and 44 males) downstream a WWTP. For both sexes, the gonadosomatic index (GSI) and gonadal histology were examined and related to water chemical analysis and fish biomarkers. Female fecundity was assessed using the gravimetric method. Fish from the polluted site showed enhanced biomarker responses involved in detoxification. Also, in the polluted site, lower GSI values were attained in both sexes and females displayed lower numbers of vitellogenic oocytes. Gonadal histology showed that all maturation stages of testicles and ovaries were present at the two study sites but fish males from the polluted site had smaller diameter seminiferous tubules. Water chemical analysis confirmed greater presence of EDCs in the river downstream the industrial WWTP. The chemicals benzotriazole and benzothiazole could be partially responsible for the observed alterations in the reproductive biology of S. laietanus.

Ecological Risk Assessment of Urban Streams Using Fish Biomarkers of DNA Damage and Physiological Responses

Ecological Risk Assessment of Urban Streams Using Fish Biomarkers of DNA Damage and Physiological Responses

Multiple biomarkers response in a Neotropical fish exposed to paralytic shellfish toxins (PSTs)

The Alagados Reservoir (Southern Brazil) is used as water supply, and since 2002 there have been reports with a presence of cyanobacterial blooms and cyanotoxins. In order to assess the water quality and the ecological integrity of the reservoir, we evaluated biochemical, genotoxic and osmoregulatory biomarkers in the freshwater cichlid fish (Geophagus brasiliensis) that were exposed to PSTs. The fish were sampled in the Alagados Reservoir in February 2016 (Summer) and were divided in three groups: 1) Reservoir group (RES): fish were collected immediately after sampling; 2) Depuration group (DEP): fish were submitted to the depuration experiment for 90 days in the laboratory; and 3) Reproduction group (REP): fish were kept in the laboratory until the fertilization and the chemical analyses were performed on the offspring (F1 generation). In the RES and DEP the blood, brain, muscle, liver and gills were collected for biochemical, genotoxic and osmoregulatory biomarkers analysis. Our results showed that the fish from the Alagados Reservoir (RES) presented oxidative stress and DNA damage; and after 90 days (DEP), the antioxidant system and DNA damage were recovered. Although PSTs were considered a risk to the ecological integrity of this water body; PSTs concentrations were not found in the tissues of the F1 generation. In addition, the biomarkers used were useful tools to evaluate the effects of environment contamination.Therefore, it is necessary to develop new technologies and monitoring programs in order to reduce cyanobaterial blooms, cyanotoxins and human activities that cause the contamination in aquatic environments.

Single and joint effects of chronic exposure to chlorpyrifos and glyphosate based pesticides on structural biomarkers in Cnesterodon decemmaculatus

Worldwide freshwater bodies that cross agricultural or urban areas are exposed to mixtures of xenobiotics. In particular, pesticides are usually part of these mixtures and could come into direct or indirect contact with biota and therefore, organisms have to cope with this altered scenario and the detrimental effects of these substances. Commercial formulations of chlorpyrifos and glyphosate, and their mixtures were evaluated using a set of biomarkers in the native fish C. decemmaculatus exposed to relevant environmentally pesticides concentrations. The biomarkers measured were: histopathological indices and tissue ultrastructure in liver and nuclear abnormalities and micronuclei in erythrocytes. During 42 days adult females were exposed to the following concentrations of Clorfox and Roundup Max (chlorpyrifos and glyphosate, respectively): 0.84 nl/l and 8.4 nl/l of Clorfox (CF), 0.2 and 2 mg/l of Roundup Max (RM) and all the combinations of these concentrations. Being the low concentrations of both pesticides environmentally relevant. Nuclear abnormalities of erythrocytes were registered under CF, RM and only one mixture. Histological inflammatory alterations increased in individuals exposed to CF and two mixtures. Finally, some pesticide combinations increased the circulatory alterations in liver. Ultrastructural changes in hepatocytes were registered at all the pesticide treatments. The different biomarker responses showed in the mixtures treatments reflected complex interactions, showing the mixture of the low concentrations of both pesticides (the environmentally relevant), potentiated effects. According to our results the presence of these substances in freshwaters could impose important risks for natural populations by causing deleterious effects on the native fish species C. decemmaculatus.

Water quality monitoring of the Sinos River Basin, Southern Brazil, using physicochemical and microbiological analysis and biomarkers in laboratory-exposed fish

The aim of this study was to monitor the water quality of three rivers of the Sinos River Basin (SRB), southern Brazil. Five sites were selected to evaluate physicochemical and microbiological parameters and genotoxic and histopathological effects in the fish species Astyanax jacuhiensis. Eight water samples were collected from March 2012 to May 2013 at sites located in the upper, middle and lower sections of the SRB. After collection, 35 water quality parameters were analyzed and fish were exposed to water samples under laboratory conditions. Five-day biochemical oxygen demand (BOD5), thermotolerant coliforms, ammoniacal nitrogen, dissolved oxygen, aluminum, iron and manganese values exceeded the permissible limits in some samples of the three sections and the cluster analysis showed three distinct groups composed by sites located in the same section of SRB. The micronuclei (MN) and other nuclear abnormalities (NA) frequencies did not differ from the control group in any sample. Higher frequencies of lamellae with alterations, such as hypertrophy and hyperplasia of epithelial cells, epithelial lifting, aneurysm, edema and necrosis were observed in fish exposed to some water samples of the five sites. The most frequent histopathological alteration was hypertrophy of epithelial cells. Therefore, in this study, the analysis of gill histopathological alterations showed higher sensitivity than the MN test under the conditions studied. The physicochemical and microbiological parameters and histopathological analysis indicate deterioration of water quality at sites located in the three sections of the Sinos River Basin.

Polycyclic aromatic hydrocarbons levels and potential biomarkers in a native South American marine fish

Polycyclic aromatic hydrocarbons (PAHs) cause adverse effects on ecosystems and organisms from aquatic environments due to their toxicity, persistence, and bioaccumulation characteristics. Furthermore, PAH exposure in fish can induce hepatic damage and physiological/biochemical disorders. The use of biomarkers can be a useful diagnostic tool to measure the health of an ecosystem, detecting alterations in organisms that can serve as early warning indicators of pollution. The present study assesses the levels of 17 PAHs in sediments and muscle of a wild fish (Cynoscion guatucupa) from the Bahia Blanca Estuary (BBE), Argentina. The concentrations of PAHs found in fish were correlated to lipid peroxidation (thiobarbituric acid reactive substances, TBARs), the activity of metabolic enzymes (alanine aminotransferase [ALT], aspartate transaminase [AST], and lactate dehydrogenase [LDH]) in liver and muscle tissues, and the condition factor (CF) to test their usefulness as integrated biomarkers of PAH pollution in field samples. Results showed most frequency of 2–3 ring PAHs and higher concentrations of 4 ring PAHs; total PAHs ranged from 11.27 to 52.80 ng.g−1 (w.w) for fish and 37.5 to 380.5 ng.g−1 (d.w) for sediments. Total PAHs in fish positively correlated to muscle TBAR levels (p<0.05), suggesting that lipid peroxidation could be produced by the pollutants. Moreover, total PAHs in fish muscle correlated positively with muscle LDH activity (p<0.01) and negatively with liver AST and ALT activities, suggesting a shift to anaerobic metabolism under stress conditions and possible hepatic damage in C. guatucupa, respectively. The minimum CF and the maximum growing coefficient were observed with maximum concentrations of total PAHs in muscle. According to the methods and data presented, we can propose TBARs, LDH, AST/ALT, and CF as integrated early warning tools to assess PAH pollution effects in the native commercial fish Cynoscion guatucupa in South American marine environments.

An integrated approach in subtropical agro-ecosystems: Active biomonitoring, environmental contaminants, bioaccumulation, and multiple biomarkers in fish

Aquatic contamination in agricultural areas is a global problem, characterized by a complex mixture of organic and inorganic pollutants whose effects on biota are unpredictable and poorly investigated. In this context, in the present study, the Neotropical fish Prochilodus lineatus was confined in situ for 120 days in two sites with different levels of anthropic impact: 1) a fish hatchery station, within the State University of Londrina (reference site - REF) and 2) an agro-ecosystem area in one of the most productive regions of southern Brazil (experimental site - EXP). We evaluated multiple biomarkers at different levels of biological organization, such as biotransformation and antioxidant enzymes, oxidative damages, DNA damages and liver histopathology. We also evaluated the occurrence of 22 organochlorine pesticides (OCPs) and 6 trace metals in water and sediment; and 33 current-use pesticides (CUPs) in the water; besides the presence of OCPs in the liver and metals in different tissues of the confined fish. The chemical analysis confirmed that the two environments presented different levels of contamination. We verified a distribution gradient of data in the principal component analysis (PCA), separating the REF fish to one side and the fish at the agricultural area (EXP) to the other side. In general, the biomarker responses were more altered in fish from the EXP than fish from the hatchery station; and this fish presented a greater accumulation of endosulfan (an increase of 18× compared to basal value) and showed oxidative, genetic, and histological damage. Through the Biomarkers Response Index (BRI), we found that the EXP fish demonstrated a decrease in health status compared with the REF fish during the confinement time, due to their exposure to a higher concentration of contaminants. In conclusion, the use of multiple biomarkers at different response levels is an important tool for environmental monitoring.

De Novo Hepatic Transcriptome Assembly and Systems Level Analysis of Three Species of Dietary Fish, Sardinops sagax, Scomber japonicus, and Pleuronichthys verticalis.

The monitoring of marine species as sentinels for ecosystem health has long been a valuable tool worldwide, providing insight into how both anthropogenic pollution and naturally occurring phenomena (i.e., harmful algal blooms) may lead to human and animal dietary concerns. The marine environments contain many contaminants of anthropogenic origin that have sufficient similarities to steroid and thyroid hormones, to potentially disrupt normal endocrine physiology in humans, fish, and other animals. An appropriate understanding of the effects of these endocrine disrupting chemicals (EDCs) on forage fish (e.g., sardine, anchovy, mackerel) can lead to significant insight into how these contaminants may affect local ecosystems in addition to their potential impacts on human health. With advancements in molecular tools (e.g., high-throughput sequencing, HTS), a genomics approach offers a robust toolkit to discover putative genetic biomarkers in fish exposed to these chemicals. However, the lack of available sequence information for non-model species has limited the development of these genomic toolkits. Using HTS and de novo assembly technology, the present study aimed to establish, for the first time for Sardinops sagax (Pacific sardine), Scomber japonicas (Pacific chub mackerel) and Pleuronichthys verticalis (hornyhead turbot), a de novo global transcriptome database of the liver, the primary organ involved in detoxification. The assembled transcriptomes provide a foundation for further downstream validation, comparative genomic analysis and biomarker development for future applications in ecotoxicogenomic studies, as well as environmental evaluation (e.g., climate change) and public health safety (e.g., dietary screening).

Metabolic effects on carbon isotope biomarkers in fish

Carbon stable isotopes (δ13C) in animal tissues are a powerful tool for tracking biological and environmental change. However, carbon isotope signatures can be altered by both physiological and environmental factors which can cloud interpretation in their use as biomarkers. We investigated metabolic effects (by varying temperatures) on δ13C of three fish tissues (otolith, muscle and liver) and the proportional contributions of environmental water (dissolved inorganic carbon; DIC) and diet (metabolic sources). Juvenile Australasian snapper (Chrysophrys auratus) were laboratory-reared at four temperatures for up to two months and then δ13C in otolith, liver and muscle were measured using isotope-ratio mass spectrometry (IRMS). Temperature significantly altered δ13C signatures in all tissues. δ13C in otoliths reflected carbon signatures from diet and water DIC, with values and variation of proportional contributions influenced by temperature. In muscle and liver, we found differences in δ13C between tissues and across temperature treatments with concurrent high diet-to-tissue fractionation. We conclude that metabolic effects influenced carbon incorporation for all tissues, with otolith carbon providing valuable insights into field metabolic rates. However, metabolic effects complicated the use of soft-tissue to track diet. This study deepens our understanding of internal and external drivers of carbon isotopic signatures in fish tissues and enhances their utility as a biomarker in the field. Improved insight into biomarkers facilitates more accurate predictions of ecological and environmental change for better understanding and management of wild populations.

Mass spectrometry based detection of common vitellogenin peptides across fish species for assessing exposure to estrogenic compounds in aquatic environments

The identification of myriad of chemicals in the environment that mimic hormones and affect the endocrine functions of exposed organism is a daunting analytical challenge for environmental scientists and engineers. Many of these endocrine disrupting chemicals (EDCs) are present at very low concentrations in the aquatic systems, but yet affect the metabolic, developmental, and reproductive functions in exposed fish and wildlife. Vitellogenin (VTG) protein is a widely used biomarker in fish for assessing exposure to EDCs, and is commonly measured using species-specific immunochemical techniques. In this study, we developed a liquid chromatography tandem mass spectrometry (LC-MS/MS) method that can measure common peptides from digested VTG in multiple fish species. In the initial experiments using high resolution mass spectrometry, two peptides (ALHPELR and FIELIQLLR) were identified as common fragments in the digested VTG protein isolated from three different fish species (Pimephales promelas, Micropterus salmoides, and Fundulus heteroclitus). Then, a quantitative analysis using LC-MS/MS under selected reaction monitoring mode was developed for the detection of these two peptides in trypsin-digested plasma from female fish (positive control), estrogen-exposed male fish (test sample), and unexposed male fish (negative control) using two of the same species used for identifying the common peptides (P. promelas, and M. salmoides) and one new species (Ameiurus nebulosus) that was not included during the selection of peptides. Results from this study demonstrate the potential of LC-MS/MS as an effective cross-species method to detect VTG in fish, which can be an alternative analytical technique for assessing endocrine disruption in multiple fish species.

Biomarker responses in fish exposed to polycyclic aromatic hydrocarbons (PAHs): Systematic review and meta-analysis

Biomarkers of antioxidant and biotransformation systems are commonly used to assess polycyclic aromatic hydrocarbons (PAHs) pollution in fish. Despite their extensive application of biomarkers, contradictory results are vastly reported in the literature, even for the same species in similar contamination scenarios. This study aims to verify response patterns of biomarkers in fish exposed to PAHs. Through systematic reviews and meta-analyses, we were able to evaluate: (i) overall magnitude of PAHs effects on biotransformation and oxidative stress biomarkers; (ii) patterns of response among experimental approaches (laboratory, field and active biomonitoring), environment (marine and freshwater) and fish habitat (pelagic, demersal, etc.); (iii) effects of exposure route, time and concentration of PAHs; and (iv) which biomarkers respond best to PAHs exposure. Overall, biomarker responses were significantly affected by PAHs exposure. The activities of ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GPx) and levels of oxidized glutathione (GSSG) and lipid peroxide (LPO) significantly increased in fish exposed to PAHs, whereas catalase (CAT) and glutathione reductase (GR) activities and levels of reduced glutathione (GSH) were not affected. Amongst responsive biomarkers, EROD and GST activities significantly differed among approaches and between marine and freshwater environments, but were not affected by fish habitat. GSSG levels were higher in fish from laboratory bioassays compared to the field, but did not differ between environments nor habitats. Exposure route played a major role only for GST and GPx responses. Finally, increasing PAHs concentration and exposure time had a significant effect on all assessed biomarkers, except for CAT. We conclude that EROD and GST are robust biomarkers to assess PAHs effects in fish. Contrarily, CAT is an inadequate biomarker of PAHs exposure since no significant response was observed. Our study also highlighted some research gaps in PAHs contamination studies, such as a clear lack of active biomonitoring experiments.

Acute toxicity and effects of Roundup Original® on pintado da Amazônia.

The toxicity of Roundup Original® (GLY), a glyphosate-based herbicide widely used in crops in Mato Grosso state, was determined in hybrid fish jundiara or pintado da Amazônia. The 96h-LC50 of GLY was 13.57mgL-1. Moreover, exposure to sublethal concentrations of GLY (0, 0.37, 0.75, 2.25, 4.5, 7.5mgL-1) has not altered the survival rate (100% for all treatments). In fish liver, protein carbonyl (PC) levels as well as glutathione-S-transferase (GST) activity, reduced glutathione (GSH), and ascorbic acid (ASA) contents increased when compared to control group. Superoxide dismutase (SOD) activity was reduced and catalase (CAT) has not changed. PC content has grown in muscle and brain, and thiobarbituric acid-reactive species (TBARS) levels also increased in muscle, but in the brain, they remained unaltered. Acetylcholinesterase (AChE) activity reduced in muscle but increased in brain when compared to control group. Our results suggest that short-term exposure to GLY induced alterations in the oxidative stress biomarkers in fish and can be interfering with their survival in natural environment; besides, these findings may be considered of high ecotoxicological relevance.

Plasma biomarkers in juvenile marine fish provide evidence for endocrine modulation potential of organotin compounds

Organotin compounds, such as tributyltin (TBT) and triphenyltin (TPT), have been widely used to control marine fouling. Here, we show that organotin stimulation reduces the hormone levels in the plasma of two economically important aquaculture fish. Blood plasma samples were collected from juvenile red seabream and black rockfish exposed to environmentally realistic concentrations of TBT and TPT for 14 days. The levels of two plasma biomarkers, namely the yolk protein precursor vitellogenin (VTG) and the sex steroid 17β-estradiol (E2), were measured to determine the endocrine disrupting potential of the organotin compounds. Both organotin compounds were dose-dependently accumulated in the blood of two fish. Exposure to waterborne TBT and TBT significantly decreased the plasma VTG levels in both the juvenile fish in a dose-dependent manner. In contrast, the treatment with E2, a well-known VTG inducer, significantly increased the plasma VTG levels in both the fish. In addition, the mRNA levels of vtg were also downregulated in the liver tissues of both the fish at 100 and/or 1000 ng L−1 of TBT or TPT exposure. The plasma E2 titers were significantly suppressed at 100 and/or 1000 ng L−1 of TBT or TPT exposure for 14 days compared to their titer in the control. Since estrogen directly regulates vtg gene expression and VTG synthesis, our results reveal the endocrine disrupting potential of organotin compounds, and subsequently the endocrine modulation at early stage of fish can trigger further fluctuations in sexual differentiation, maturation, sex ration or egg production. In addition, the results demonstrate their effects on non-target organisms, particularly on animals reared in aquaculture and fisheries.