Use of intestinal Pseudomonas aeruginosa in fish to detect the environmental pollutant benzo[a]pyrene

Lead induced structural and functional damage and microbiota dysbiosis in the intestine of crucian carp (Carassius auratus)

Lead (Pb) is a hazardous pollutant in water environments that can cause significant damage to aquatic animals and humans. In this study, crucian carp (Carassius auratus) were exposed to waterborne Pb for 96 h; then, histopathological analysis, quantitative qPCR analysis, and 16S high-throughput sequencing were performed to explore the effects of Pb on intestinal bioaccumulation, structural damage, oxidative stress, immune response, and microbiota imbalance of C. auratus. After Pb exposure, the intestinal morphology was obviously damaged, including significantly increasing the thickness of the intestinal wall and the number of goblet cells and reducing the depth of intestinal crypts. Pb exposure reduced the mRNA expressions of Claudin-7 and villin-1 while significantly elevated the level of GST, GSH, CAT, IL-8, IL-10, IL-1, and TNF-α. Furthermore, 16S rRNA analysis showed that the Shannon and Simpson indices decreased at 48 h after Pb exposure, and the abundance of pathogenic bacteria (Erysipelotrichaceae, Weeksellaceae, and Vibrionaceae) increased after Pb exposure. In addition, the correlation network analysis found that Proteobacteria were negatively correlated with Firmicutes and positively correlated with Bacteroidetes. Functional prediction analysis of bacteria speculated that the change in intestinal microbiota led to the PPAR signaling pathway and peroxisome function of the intestine of crucian carp was increased, while the immune system and membrane transport function were decreased. Finally, canonical correlation analysis (CCA) found that there were correlations between the intestinal microbiota, morphology, antioxidant factors, and immune factors of crucian carp after Pb exposure. Taken together, our results demonstrated that intestinal flora dysbiosis, morphological disruption, oxidative stress, and immune injury are involved in the toxic damage of Pb exposure to the intestinal structure and function of crucian carp. Meanwhile, Pb exposure rapidly increased the abundance of pathogenic bacteria, leading to intestinal disorders, further aggravating the damage of Pb to intestinal structure and function. These findings provide us a basis for the link between gut microbiome changes and heavy metal toxicity, and gut microbiota can be used as biomarkers for the evaluation of heavy metal pollution in future.

Are the tourist beaches safe for swimming? A case study of health risks of polycyclic aromatic hydrocarbons (PAHs) in tourist beaches of Bushehr City

The aims of the present research were to evaluate the health risk of long-term exposure to polycyclic aromatic hydrocarbons (PAHs) concerning the human, ecotoxicological risk for marine biota, and identify their possible sources. Surface sediment bioassay samples were collected from 15 stations of tourist beaches surrounding Bushehr City and analyzed using high performance liquid chromatography (HPLC). The results indicated the concentrations of ∑PAH ranged from 193.5 to 725.5 ng g^-1 with mean value of 351.1 ± 155.2 ng g^-1, which could be considered as moderate level of pollution. Measured levels of PAH in sediments were compared with sediment quality guidelines (SQGs), indicating low to medium ecotoxicological risk on marine organisms. Moreover, mean ERM quotient (M-ERM-Q) and mean PEL quotient (M-PEL-Q) were implemented, demonstrating potentially biological adverse effects. A preliminary evaluation of human health risk using incremental lifetime cancer risk (ILCR) and toxic equivalent quotient (TEQ^carc) indicated that PAH-contaminated sediment in some stations of touristic beaches of Bushehr City would induce potential carcinogenic effects especially for children. Composition and diagnostic analysis indicated that PAHs originated from both pyrogenic and petrogenic, with higher portion of incomplete combustion PAHs.

Formation and weathering assessment of oil-suspended sediment aggregates through a laboratory investigation

Formation of oil-suspended sediment aggregates (OSAs) is believed to be one of the natural cleaning processes in the marine environment. In this study, we have investigated the formation processes of OSAs under different mixing periods (continuous mixing and with the addition of sediments in between), oil-sediment ratios (1:1, 1:2 and 2:1) and crude oils (Arabian Light (AL), Kuwait (KW) and Murban (MB)). The results revealed that size of OSAs significantly increased (up to ≈ 1.41 mm) with the addition of sediments. Aggregates (total 36) were extracted for n-alkanes and polycyclic aromatic hydrocarbons to quantify and assess their weathering and toxic levels. The maximum n-alkane depletion was 84% (111-02), 94% (212-02) and 84% (321-02) and PAH depletion was ≈ 72% (111-02), 79% (212-02) and 81% (311-03) for the OSAs of AL, KW and MB crude oils, respectively, for the different samples considered, indicating that n-alkanes were depleted relatively higher than the PAHs. The highest depletion of both n-alkane and PAHs has occurred in OSAs of 10-h continuous mixing. The depletion of both n-alkane and PAHs reduced after the addition of sediments, however, escalated the growth of OSAs, resulting in bigger size OSAs. The concentration of PAHs of all 36 OSAs is greater than 5000 ng/g, indicating very high PAH pollution. Though the formation of OSAs helps in cleaning the spill sites, the carcinogenic threat to the marine ecosystem caused by these OSAs cannot be ignored.

Differential responses of gut microbiota of male and female fathead minnow (Pimephales promelas) to a short-term environmentally-relevant, aqueous exposure to benzo[a]pyrene

In addition to aiding in digestion of food and uptake of nutrients, microbiota in guts of vertebrates are responsible for regulating several beneficial functions, including development of an organism and maintaining homeostasis. However, little is known about effects of exposures to chemicals on structure and function of gut microbiota of fishes. To assess effects of exposure to polycyclic aromatic hydrocarbons (PAHs) on gut microbiota, male and female fathead minnows (Pimephales promelas) were exposed to environmentally-relevant concentrations of the legacy PAH benzo[a]pyrene (BaP) in water. Measured concentrations of BaP ranged from 2.3 × 10^-3 to 1.3 μg L^-1. The community of microbiota in the gut were assessed by use of 16S rRNA metagenetics. Exposure to environmentally-relevant aqueous concentrations of BaP did not alter expression levels of mRNA for cyp1a1, a "classic" biomarker of exposure to BaP, but resulted in shifts in relative compositions of gut microbiota in females rather than males. Results presented here illustrate that in addition to effects on more well-studied molecular endpoints, relative compositions of the microbiota in guts of fish can also quickly respond to exposure to chemicals, which can provide additional mechanisms for adverse effects on individuals.

Hydrocarbon-Oxidizing Bacteria in the Digestive System of Fish as an Indicator of Coastal Pollution

Assessment of pollution of marine environment and biota with hydrocarbons is of particular importance, since oil products are among the priority pollutants of many seas. Development of new environmental toxicological biomarkers is one of the promising methods of integrated assessment of pollution effects. Here, the first investigation on the abundance of hydrocarbon-oxidizing bacteria in the digestive system of coastal fish (stickleback, dace, white bream, common bleak, perch, gudgeon, and roach) from the eastern Gulf of Finland, Baltic Sea has been performed. The results reflect changes occurring in the environment and indicate contamination of water and sediments with oil and oil products. The relative abundance of hydrocarbon-oxidizing bacteria in the digestive tract of fish is an effective, sensitive, and low-cost indicator of environmental pollution that can be used in monitoring and environmental impact assessment of the aquatic ecosystems.

Co-inertia multivariate approach for the evaluation of anthropogenic impact on two commercial fish along Tyrrhenian coasts

Aliphatic hydrocarbon levels were determined by the GC/MS technique in fish livers of Engraulis encrasicolus (Ee) and Trachurus trachurus (Tt), collected from a particular area of the Mediterranean Sea, called GSA 10, which is located exactly in Tyrrhenian Sea between Campania coast and North Sicily coast. The aim was to evaluate their potential use as specific bioindicators towards this class of contaminants. Both Tt and Ee are considered to be pollution monitoring bioindicators, due to their dominance in marine communities and economic fishing interest. Ee showed a higher tendency to bioaccumulate TAHs, due to the lower quantity of fatty acids in liver tissues with respect to Tt. The area under study has been characterised a) chemically with the acquisition of temperature, oxygen and salinity profiles along the water column, and b) ecologically with the determination of amino acid contents in fish eyes, in order to gain information on the adaptation to environmental changes. Moreover, specific activities of two hydrolytic enzymes, such as alkaline phosphatase and peroxidase in fish epidermal mucus, together with lactate in blood plasma and cortisol levels, have been investigated for the first time, in order to obtain insights into the effects of hydrocarbons on animal welfare. A multiple co-inertia analysis was also applied to chemical and environmental parameters, in order to explore any possible correlation between different variables. The multivariate approach showed a clear spatial distribution between environmental and chemical variables in Ee, whilst there was an absence of a spatial trend in Tt. Moreover, the chemometric analysis showed a very high correlation between amino acid profiles and environmental variables for both species, confirming the possibility of being used as ecological welfare indices for short-term environmental variations.

Seasonal variability of anthropogenic indices of PAHs in sediment from the Kuala Selangor River, west coast Peninsular Malaysia

Rapid increase in industrialization and urbanization in the west coast of Peninsular Malaysia has led to the intense release of petroleum and products of petroleum into the environment. Surface sediment samples were collected from the Selangor River in the west coast of Peninsular Malaysia during four climatic seasons and analyzed for PAHs and biomarkers (hopanes). Sediments were soxhlet extracted and further purified and fractionated through first and second step column chromatography. A gas chromatography-mass spectrometry (GC-MS) was used for analysis of PAHs and hopanes fractions. The average concentrations of total PAHs ranged from 219.7 to 672.3 ng g^-1 dw. The highest concentrations of PAHs were detected at 964.7 ng g^-1 dw in station S5 in the mouth of the Selangor River during the wet inter-monsoonal season. Both pyrogenic and petrogenic PAHs were detected in the sediments with a predominance of the former. The composition of hopanes was homogeneous showing that petroleum hydrocarbons share an identical source in the study area. Diagnostic ratios of hopanes indicated that some of the sediment samples carry the crankcase oil signature.

Distribution, source apportionment and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in intertidal sediment of Asaluyeh, Persian Gulf

Surface sediment samples were collected from intertidal zone of Asaluyeh, Persian Gulf, to investigate distribution, sources and health risk of sixteen polycyclic aromatic hydrocarbons (PAHs). Total PAH concentrations ranged from 1.8 to 81.2 μg kg^-1 dry weight, which can be categorized as low level of pollution. Qualitative and quantitative assessments showed that PAHs originated from both petrogenic and pyrogenic sources with slight pyrogenic dominance. Source apportionment using principal component analysis indicated that the main sources of PAHs were fossil fuel combustion (33.59%), traffic-related PAHs (32.77%), biomass and coal combustion (18.54%) and petrogenic PAHs (9.31%). According to the results from the sediment quality guidelines, mean effects range-median quotient (M-ERM-Q) and benzo[a]pyrene toxic equivalents (BaP_eq), low negative ecological risks related to PAH compounds would occur in the intertidal zone of Asaluyeh. The total benzo[a]pyrene (BaP) toxic equivalent quotient (TEQ^carc) for carcinogenic compounds ranged from 0.01 to 7 μg kg^-1-BaP_eq, indicating low carcinogenic risk. The human health risk assessment of PAH compounds via ingestion and dermal pathways suggests low and moderate potential risk to human health, respectively.

Bioavailability of polycyclic aromatic hydrocarbons (PAHs) to short-neck clam (Paphia undulata) from sediment matrices in mudflat ecosystem of the west coast of Peninsular Malaysia

The bioaccumulation and bioavailability of polycyclic aromatic hydrocarbons (PAHs) were characterized in sediment and Paphia undulata (short-neck clam) from six mudflat areas in the west coasts of Peninsular Malaysia. The concentrations of total PAHs varied from 357.1 to 6257.1 and 179.9 ± 7.6 to 1657.5 ± 53.9 ng g ^-1 dry weight in sediment and short-neck clam samples, respectively. PAHs can be classified as moderate to very high level of pollution in sediments and moderate to high level of pollution in short-neck clams. The diagnostic ratios of individual PAHs and principal component analysis indicate both petrogenic and pyrogenic sources with significant dominance of pyrogenic source. The first PAHs biota-sediment accumulation factors and relative biota-sediment accumulation factors data for short-neck clam were obtained in this study, indicating a preferential accumulation of lower molecular weight PAHs. Evaluation of PAH levels in sediments and short-neck clams indicates that short-neck clam could be introduced as a good biomonitor in mudflats. The results also demonstrated that under environmental conditions, the sedimentary load of hydrocarbons appears to be one of the factors controlling their bioavailability to biota.

Nanoporous Gold Films Prepared by a Combination of Sputtering and Dealloying for Trace Detection of Benzo[a]pyrene Based on Surface Plasmon Resonance Spectroscopy

A wavelength-interrogated surface plasmon resonance (SPR) sensor based on a nanoporous gold (NPG) film has been fabricated for the sensitive detection of trace quantities of benzo[a]pyrene (BaP) in water. The large-area uniform NPG film was prepared by a two-step process that includes sputtering deposition of a 60-nm-thick AuAg alloy film on a glass substrate and chemical dealloying of the alloy film in nitric acid. For SPR sensor applications, the NPG film plays the dual roles of analyte enrichment and supporting surface plasmon waves, which leads to sensitivity enhancement. In this work, the as-prepared NPG film was first modified with 1-dodecanethiol molecules to make the film hydrophobic so as to improve BaP enrichment from water via hydrophobic interactions. The SPR sensor with the hydrophobic NPG film enables one to detect BaP at concentrations as low as 1 nmol·L^-1. In response to this concentration of BaP the sensor produced a resonance-wavelength shift of Δλ_R = 2.22 nm. After the NPG film was functionalized with mouse monoclonal IgG1 that is the antibody against BaP, the sensor's sensitivity was further improved and the BaP detection limit decreased further down to 5 pmol·L^-1 (the corresponding Δλ_R = 1.77 nm). In contrast, the conventional SPR sensor with an antibody-functionalized dense gold film can give a response of merely Δλ_R = 0.9 nm for 100 pmol·L^-1 BaP.

A comparison of biomarker responses in juvenile diploid and triploid African catfish, Clarias gariepinus, exposed to the pesticide butachlor

Influence of waterborne butachlor (BUC), a commonly used pesticide, on morphometric, biochemical, and molecular biomarkers was evaluated in juvenile, full sibling, diploid and triploid African catfish (Clarias gariepinus). Fish were exposed for 21 days to one of three concentrations of BUC [mean measured µg/L: 22, 44 or 60]. Unexposed (control) triploids were heavier and longer and had higher visceral-somatic index (VSI) than diploids. Also, they had lighter liver weight (HSI) and showed lower transcript levels of brain gonadotropin-releasing hormone (GnRH), aromatase (cyp191b) and fushi tarazu-factor (ftz-f1), and plasma testosterone levels than diploids. Butachlor treatments had no effects, in either diploid or triploid fish, on VSI, HSI, weight or length changes, condition factor (CF), levels of plasma testosterone, 17-β estradiol (E2), cortisol, cholesterol, or mRNA levels of brain tryptophan hydroxylase (tph2), forkhead box L2 (foxl2), and 11 β-hydroxysteroid dehydrogenase type 2 (11β-hsd2). Expressions of cyp191b and ftz-f1 in triploids were upregulated by the two highest concentrations of BUC. In diploid fish, however, exposures to all BUC concentrations decreased GnRH transcription and the medium BUC concentration decreased ftz-f1 transcription. Substantial differences between ploidies in basal biomarker responses are consistent with the reported impaired reproductive axis in triploid C. gariepinus. Furthermore, the present study showed the low impact of short term exposure to BUC on reproductive axis in C. gariepinus.

Virgin microplastics cause toxicity and modulate the impacts of phenanthrene on biomarker responses in African catfish (Clarias gariepinus)

Despite the ubiquity of microplastics (MPs) in aquatic environments and their proven ability to carry a wide variety of chemicals, very little is known about the impacts of virgin or contaminant-loaded MPs on organisms. The primary aim of this study was to investigate the impacts of virgin or phenanthrene (Phe)-loaded low-density polyethylene (LDPE) fragments on a suite of biomarker responses in juvenile African catfish (Clarias gariepinus). Virgin LDPE (50 or 500µg/L) were preloaded with one of two nominal Phe concentrations (10 or 100µg/L) and were exposed to the fish for 96h. Our findings showed one or both Phe treatments significantly increased the degree of tissue change (DTC) in the liver while decreased the transcription levels of forkhead box L2 (foxl2) and tryptophan hydroxylase2 (tph2) in the brain of C. gariepinus. Exposure to either levels of virgin MPs increased the DTC in the liver and plasma albumin: globulin ratio while decreased the transcription levels of tph2. Moreover, MPs modulated (interacted with) the impact of Phe on the DTC in the gill, plasma concentrations of cholesterol, high-density lipoprotein (HDL), total protein (TP), albumin, and globulin, and the transcription levels of fushi tarazu-factor 1 (ftz-f1), gonadotropin-releasing hormone (GnRH), 11 β-hydroxysteroid dehydrogenase type 2 (11β-hsd2), and liver glycogen stores. Results of this study highlight the ability of virgin LDPE fragments to cause toxicity and to modulate the adverse impacts of Phe in C. gariepinus. Due to the wide distribution of MPs and other classes of contaminants in aquatic environments, further studies are urgently needed to elucidate the toxicity of virgin or contaminant-loaded MPs on organisms.

Basin-Scale Study on the Multiphase Distribution, Source Apportionment and Risk Assessment of PAHs in the Hai River Water System

As a systematic research at basin scale, this study explored the composition and concentration characteristics of 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediments, water, and suspended particulate matter (SPM) in the water systems (rivers, lakes, and reservoirs) in the Hai River Basin through literature review. The sources and the ecosystem risks of PAHs in the sediments in the entire basin were specially discussed with diagnostic ration, PAHs composition, and an improved risk quotient method. Results showed that the total concentration of PAHs varied from 99.65 to 25,303 ng g(-1) dry weight in sediments, from 51.0 to 559.1 ng L(-1) in water, and from 4528 to 51,080 ng g(-1) dry weight in SPM, respectively. The dominant PAHs in the three examined phases were 2-3 rings in most waterbodies. PAHs in the rivers were from mixed sources (petrogenic and pyrolytic inputs), whereas those in lakes and reservoirs were mainly from biomass combustion and petroleum combustion. PAHs in the entire basin exhibited moderate to high ecological risk, and the rivers (especially Hai River, Jiyun River, Chaobai River, and Beiyun River) suffered higher ecological risk than reservoirs and lakes. Most of the rivers with higher PAHs risk flow through or around megacity Beijing and Tianjin.

Alterations in juvenile diploid and triploid African catfish skin gelatin yield and amino acid composition: Effects of chlorpyrifos and butachlor exposures

Skin is a major by-product of the fisheries and aquaculture industries and is a valuable source of gelatin. This study examined the effect of triploidization on gelatin yield and proximate composition of the skin of African catfish (Clarias gariepinus). We further investigated the effects of two commonly used pesticides, chlorpyrifos (CPF) and butachlor (BUC), on the skin gelatin yield and amino acid composition in juvenile full-sibling diploid and triploid African catfish. In two separate experiments, diploid and triploid C. gariepinus were exposed for 21 days to graded CPF [mean measured: 10, 16, or 31 μg/L] or BUC concentrations [Mean measured: 22, 44, or 60 μg/L]. No differences in skin gelatin yield, amino acid or proximate compositions were observed between diploid and triploid control groups. None of the pesticide treatments affected the measured parameters in diploid fish. In triploids, however, gelatin yield was affected by CPF treatments while amino acid composition remained unchanged. Butachlor treatments did not alter any of the measured variables in triploid fish. To our knowledge, this study is the first to investigate changes in the skin gelatin yield and amino acid composition in any animal as a response to polyploidization and/or contaminant exposure.

Diploid and triploid African catfish (Clarias gariepinus) differ in biomarker responses to the pesticide chlorpyrifos

The impacts of environmental stressors on polyploid organisms are largely unknown. This study investigated changes in morphometric, molecular, and biochemical parameters in full-sibling diploid and triploid African catfish (Clarias gariepinus) in response to chlorpyrifos (CPF) exposures. Juvenile fish were exposed to three concentrations of CPF (mean measured μg/L (SD): 9.71 (2.27), 15.7 (3.69), 31.21 (5.04)) under a static-renewal condition for 21days. Diploid control groups had higher hepatosomatic index (HSI), plasma testosterone (T), and brain GnRH and cyp19a2 expression levels than triploids. In CPF-exposed groups, changes in HSI, total weight and length were different between the diploid and triploid fish. In contrast, condition factor did not alter in any of the treatments, while visceral-somatic index (VSI) changed only in diploids. In diploid fish, exposure to CPF did not change brain 11β-hsd2, ftz-f1, foxl2, GnRH or cyp19a2 mRNA levels, while reduced tph2 transcript levels compared to the control group. In contrast, 11β-hsd2 and foxl2 expression levels were changed in triploids following CPF exposures. In diploids, plasma T levels showed a linear dose-response reduction across CPF treatments correlating with liver weight and plasma total cholesterol concentrations. In contrast, no changes in plasma cholesterol and T concentrations were observed in triploids. Plasma cortisol and 17-β estradiol (E2) showed no response to CPF exposure in either ploidy. Results of this first comparison of biomarker responses to pesticide exposure in diploid and polyploid animals showed substantial differences between diploid and triploid C. gariepinus.

Acute phenanthrene toxicity to juvenile diploid and triploid African catfish (Clarias gariepinus): Molecular, biochemical, and histopathological alterations

Information on the biological responses of polyploid animals towards environmental contaminants is scarce. This study aimed to compare reproductive axis-related gene expressions in the brain, plasma biochemical responses, and the liver and gill histopathological alterations in diploid and triploid full-sibling juvenile African catfish (Clarias gariepinus). Fish were exposed for 96 h to one of the two waterborne phenanthrene (Phe) concentrations [mean measured (SD): 6.2 (2.4) and 76 (4.2) μg/L]. In triploids, exposure to 76 μg/L Phe increased mRNA level of fushi tarazu-factor 1 (ftz-f1). Expression of tryptophan hydroxylase2 (tph2) was also elevated in both ploidies following the exposure to 76 μg/L Phe compared to the solvent control. In triploids, 76 μg/L Phe increased plasma alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels compared to the other Phe-exposed group. It also elevated lactate and glucose contents relative to the other groups. In diploids, however, biochemical biomarkers did not change. Phenanthrene exposures elevated glycogen contents and the prevalence of histopathological lesions in the liver and gills of both ploidies. This study showed substantial differences between diploids and triploids on biochemical and molecular biomarker responses, but similar histopathological alterations following acute Phe exposures.

Ploidy-, gender-, and dose-dependent alteration of selected biomarkers in Clarias gariepinus treated with benzo[a]pyrene

Naturally-occurring and artificially-induced polyploids have been documented in various fish species but to date no comparison has been reported of the impacts of ploidy on fish biomarker responses to organic pollutants. This study describes effects of ploidy, gender, and dose on biliary fluorescent aromatic compound (FAC) concentrations, hepatic ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities in one of the most commonly cultured warm-water species, the African catfish Clarias gariepinus. Recently matured male and female diploid and triploid fish were intraperitoneally (i.p.) injected with 0, 5 or 25mg/kg benzo[a]pyrene (BaP) and liver and gallbladder were sampled 48hr later. No significant differences were found between ploidies in bile concentrations of 7,8 dihydrodiolbenzo[a]pyrene (7,8D BaP), 1-hydroxybenzo[a]pyrene (1-OH BaP) or 3-hydroxybenzo[a]pyrene (3-OH BaP). However, concentrations of the biliary FACs did differ between males and females at different dose of injection with generally higher concentrations in females at the low dose of BaP and higher concentrations in males at the higher BaP concentration. Hepatic EROD activity did not exhibit gender-dependent difference, whereas it was significantly higher in triploids than diploids. GST activities were not significantly influenced by any of the tested factors. This work advanced our understanding of the role of ploidy, gender, and dose in biotransformation of pollutants in fish.

Glutathione S-transferase activities in African catfish injected with β-naphthoflavone: effects of ploidy, gender, dose, and sampling time

Glutathione S-transferases (GST) are considered among the most controversial biomarkers of water pollutants in fish with little known about factors influencing their activities. The objective of this study was to investigate how gender, dose, ploidy, and sampling time alter hepatic GST activities in African catfish (Clarias gariepinus) following β-naphthoflavone (β-NF) injection. Newly matured male and female diploid and triploid fish were intraperitoneally (i.p.) injected with 0, 15, or 75 mg/kg of β-NF, and livers were excised 24, 48, and 72 h post-injection. Results showed that hepatic GST activities were significantly inhibited by both doses of β-NF. Inhibition was greater in females than males, but no significant differences were observed between diploid and triploid fish. Enzymatic activities differed over time with lowest levels 72 h post-injection. These results extend our understanding of GST activity in fish and highlight the necessity of considering confounding factors when comparing different studies.

Evaluation of waterborne exposure to heavy metals in innate immune defences present on skin mucus of gilthead seabream (Sparus aurata)

Aquatic animals are continuously exposed to chemical pollutants but the effects evoked in skin surfaces, which receive the most direct contact with them, are poorly investigated. Terminal carbohydrate composition and immunological components present in skin mucus of gilthead seabream (Sparus aurata L.) specimens exposed to waterborne sublethal dosages of heavy metals [arsenic (As2O3), cadmium (CdCl2) and mercury (CH3HgCl) at 5, 5 and 0.04 μM, respectively for 2, 10 and 30 days were analysed. Moreover, the presence of a fucose binding lectin (FBL) was evaluated by western blot and the protein profiles were by SDS-PAGE and HPLC. Results showed little effects of heavy metals in the presence of several terminal carbohydrates with few increments or decrements. Most of the enzyme activities related to immune responses were increased upon heavy metal exposure in the skin mucus including bactericidal activity. Methylmercury produced the most dramatic changes increasing all the activities. Moreover, the FBL was undetected in any of the control fish skin mucus but was evident in all the heavy metal exposed fish. In addition, As and Cd produced a clear change in the protein profile as evidenced by the lack of a protein band of around 12 kDa which is absent. These protein changes were more evident with the HPLC study showing the presence of different peaks and differences in intensity. The present results could be useful for better understanding the role and their behaviour of the mucosal immunity in skin as a key component of the innate immune system against pollutants.

Distributions and source apportionment of sediment-associated polycyclic aromatic hydrocarbons (PAHs) and hopanes in rivers and estuaries of Peninsular Malaysia

In this study, the distributions and sources of sediment-associated polycyclic aromatic hydrocarbons (PAHs) and hopanes in the Malaysian rivers and estuaries were evaluated. The concentrations of 16 USEPA PAHs varied from 225.5 to 293.9 (Perlis River), 195.2 to 481.2 (Kedah River), 791.2 to 1995.4 (Merbok River), 231.2 to 426.7 (Perak River), and 3803.2 to 7442.7 ng g(-1) (Klang River) dry weight. PAHs can be classified as moderate in the Perlis, Kedah, and Perak Rivers, moderate to high in the Merbok River, and high to very high in the Klang River. The comparison of PAHs with sediment quality guidelines (SQGs) indicates that occasionally adverse biological effects may occur from total PAHs, low molecular weight (LMW), and high molecular weight (HMW) PAHs at stations 1, 2, and 3 of the Klang River and from total PAHs at station 2 of the Merbok River. The diagnostic ratios of individual PAHs indicate both petrogenic and pyrogenic origin PAHs with significant dominance of pyrogenic sources in the study areas. The results suggest that Malaysian sediments had hopane ratios (C29/C30) similar to MECO suggesting MECO as a major source of the petroleum hydrocarbons found in the sediments, which is consistent with results reported in previous studies. These findings demonstrate that effective and improved environmental regulations in Malaysia have shifted the source of petroleum hydrocarbons from petrogenic to pyrogenic origin.

Baseline distributions and sources of Polycyclic Aromatic Hydrocarbons (PAHs) in the surface sediments from the Prai and Malacca Rivers, Peninsular Malaysia

In this study, the surface sediments of the Malacca and Prai Rivers were analyzed to identify the distributions, and sources of Polycyclic Aromatic Hydrocarbons (PAHs). The total PAH concentrations varied from 716 to 1210 and 1102 to 7938 ng g(-1)dw in the sediments of the Malacca and Prai Rivers, respectively. The PAH concentrations can be classified as moderate and high level of pollution in the sediments of the Malacca and Prai Rivers, respectively. The comparison of PAHs with the Sediment Quality Guidelines (SQGs) indicates that the PAHs in the sediments of the Malacca and Prai Rivers may have the potential to cause adverse toxicity effects on the sampled ecosystems. The diagnostic ratios of individual PAHs indicate both petrogenic- and pyrogenic-origin PAHs with dominance of pyrogenic source in both rivers. These findings demonstrate that the environmental regulations in Malaysia have effectively reduced the input of petrogenic petroleum hydrocarbons into rivers.