Gut morphology and metallothionein immunoreactivity inLiza auratafrom different heavy metal polluted environments

Effescts of acute diclofenac exposure on intestinal histology, antioxidant defense, and microbiota in freshwater crayfish (Procambarus clarkii)

In the present study, we exposed Procambarus clarkii to different doses (0, 1, and 10 mg/L) of diclofenac (DCF). Meanwhile, we investigated the effects of exposure to DCF on intestinal histology, antioxidant defense, and microbial communities in P. clarkii. The results showed DCF caused histological changes in the intestines. Additionally, DCF induced significant changes in the expression of antioxidant genes including Mn-sod, cat, gst, and gpx. High-throughput sequencing of 16 S rRNA gene revealed DCF changed the diversity, richness, and composition of intestinal microbial communities. The relative abundances of the predominant phyla Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria showed significant changes at the phylum level after treatment with DCF. At the genus level, the most predominant genera with marked differences in abundance were Lucibacterium, Shewanella, Bacteroides, Anaerorhabdus, Aeromonas, Acinetobacter, Clostridium XlVb, Arcobacter, Bosea, and so on. To conclude, treatment with DCF could cause intestinal histological damage, induce significant changes of the expression of intestinal antioxidant genes, and impact the composition of intestinal microbiota in P. clarkii. This research will provide novel insights into the toxic effects of DCF on aquatic crustaceans.

Growth, antioxidant capacity, intestinal morphology, and metabolomic responses of juvenile Oriental river prawn (Macrobrachium nipponense) to chronic lead exposure

Understanding the mechanisms of metal toxicity to organisms farmed for food may suggest mitigation strategies. We determined the 24-, 48-, 72-, and 96-h median lethal concentrations of lead in juvenile oriental river prawn (Macrobrachium nipponense). The prawns were then exposed to sub-lethal concentrations (13.13 and 26.26 μg/L) of lead for 60 days and growth, antioxidant enzyme activity, intestinal morphology, and metabolite profiles were assessed. Prawns exposed to 26.26 μg/L but not to 13.13 μg/L lead exhibited lower weight gain than controls. The lead burden in muscle was 0.067 and 0.25 μg/g of dry weight exposed to 13.13 and 26.26 μg/L, respectively. Levels of glutamic oxaloacetic transaminase and glutamic-pyruvic transaminase were not altered following exposure. Exposure increased malondialdehyde activity in the hepatopancreas and decreased superoxide dismutase and glutathione peroxidase activities. Catalase activity first increased and then decreased as lead concentrations increased. Some intestinal epithelial cells disassociated from the basement membrane in prawns exposed to 13.13 μg/L lead. Intestinal epithelial cells in prawns exposed to 26.26 μg/L lead separated completely from the basement membrane. Gas chromatography-mass spectrometry metabolomics assays showed the 13.13-μg/L exposure did not elicit significant metabolic alterations. Exposure to 26.26 μg/L lead differentially up-regulated 58 metabolites and down-regulated 21 metabolites. The metabolites identified were involved in galactose, purine, glutathione, and carbon metabolism, biosynthesis of amino acids and steroids, and neuroactive ligand-receptor interaction. These data indicate that chronic lead exposure can adversely affect growth, increase accumulation in muscle, impair intestinal morphology, and induce oxidant stress or neurotoxicity-related effects in M. nipponense.

Evaluation of architectural and histopathological biomarkers in the intestine of brown trout (Salmo trutta Linnaeus, 1758) challenged with environmental pollution

In the present study novel histopathological approach, using fish intestine as a sensitive bioindicator organ of pollution impact in the freshwater ecosystem, was proposed. Histopathological alterations were compared between native brown trout (Salmo trutta Linnaeus, 1758) from the reference (Krka River spring) and pollution impacted location (influence of technological/municipal wastewaters and agricultural runoff near the Town of Knin) of the karst Krka River in Croatia. In brown trout from both locations, severe parasitic infestation with acanthocephalan species Dentitruncus trutae was found, enabling evaluation of acanthocephalan infestation histopathology, which indicated parasite tissue reaction in a form of inflammatory, necrotic and hyperplastic response that extended throughout lamina epithelialis mucosae, lamina propria, and lamina muscularis mucosae. New semi-quantitative histological approach was proposed in order to foresee alterations classified in three reaction patterns: control tissue appearance, moderate (progressive) tissue impairment and severe (regressive and inflammatory) tissue damage. The most frequent progressive alteration was hyperplasia of epithelium on the reference site, whereas the most frequent regressive alterations were atrophy and necrosis seen on the polluted site. Furthermore, histopathological approach was combined with micromorphological and macromorphological assessment as an additional indicator of pollution impact. Among 15 observed intestinal measures, two biomarkers of intestinal tissue damage were indicated as significant, height of supranuclear space (hSN) and number of mucous cells over 100 μm fold distance of intestinal mucosa (nM), which measures were significantly lower in fish from polluted area compared to the reference site. Obtained results indicated that combined histological and morphological approach on fish intestinal tissue might be used as a valuable biological tool for assessing pollution impact on aquatic organisms. Therefore, semi quantitative scoring and multiparametric morphological assessment of intestinal tissue lesion magnitude should become a common approach to handle environmental pollution impact.

Metallothioneins and heat shock proteins 70 in Armadillidium vulgare (Isopoda, Oniscidea) exposed to cadmium and lead

The heavy metals bioaccumulation capability in Armadillidium vulgare feeded with chestnut leaves contaminated with various sublethal concentrations of Cd and Pb, was evaluated under laboratory conditions. The metal concentration found in the hepatopancreas of treated animals, as measured by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), affected the expression and localization of MT and HSP70 as shown by immunohistochemical and western blotting analysis. The Cd content of the animals treated with the various concentrations of the metal has been always higher than that of chestnut leaves contaminated. The accumulation of Pb was, instead, always modest compared to the content of the chestnut leaves. The immunohistochemical investigation in hepatopancreas tissue of animals treated with increasing concentrations of Cd and Pb, by using the anti-MT and anti-HSP70 antibodies, has provided a response clearly positive even if differentiated in relation to the metal and concentration tested. In particular, a positive response to anti-MT antibody was detected in B and S cells nuclei and S cells cytoplasm; the localization of HSP70 was particularly intense at the cell surface. Western blotting analysis showed significant up-regulation of the expression (about 2.6 fold) of HSP70 proteins in the hepatopancreas of animals exposed to highest Pb concentrations respect to control. Moreover, samples exposed to higher Cd and Pb concentrations showed a higher expression of MT (3.2 fold and 4 fold respectively) compared to control. In summary, our data beyond to clearly demonstrate for the first time the expression of MT in terrestrial isopods, suggest that A. vulgare would be a suitable organism for assessing Cd and Pb exposure in environments threatened by metal pollution as suggested by the modulation of the biomarkers MT and HSP70.

Impact of environmental pollution on caged mussels Mytilus galloprovincialis using NMR-based metabolomics

Metabolic responses to environmental pollution, mainly related to Hg and PAHs, were investigated in mussels. Specimens of Mytilus galloprovincialis, sedentary filter-feeders, were caged in anthropogenic-impacted and reference sites along the Augusta coastline (Sicily, Italy). The gills, mainly involved in nutrient uptake, digestion and gas exchange, were selected as target organ being the first organ to be affected by pollutants. Severe alterations in gill tissue were observed in mussels from the industrial area compared with control, while gill metabolic profiles, obtained by (1)H NMR spectroscopy and analyzed by multivariate statistics, exhibited significant changes in amino acids, energy metabolites, osmolytes and neurotransmitters. Overall, the morphological changes and metabolic disturbance detected in gill tissues may suggest that the mussels transplanted to the contaminated field site were suffering from adverse environmental condition. The concurrent morphological and metabolomic investigations as applied here result effective in assessing the environmental influences on health status of aquatic organisms.

Antioxidant responses versus DNA damage and lipid peroxidation in golden grey mullet liver: a field study at Ria de Aveiro (Portugal)

The present work aimed to investigate golden grey mullet (Liza aurata) liver protection versus damage responses at a polluted coastal lagoon, Ria de Aveiro (Portugal), as a tool to evaluate the human impacts on environmental health at five critical sites in Ria de Aveiro (Portugal) in comparison to a reference site (Torreira; TOR). Protection was evaluated by measuring non-enzymatic [total glutathione (GSHt) and non-protein thiols (NPT)] and enzymatic [catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GR)] antioxidant defenses. Damage was assessed as DNA integrity loss and lipid peroxidation (LPO). No significant differences were found between sites in terms of non-enzymatic defenses (GSHt and NPT). CAT did not display significant differences among sites. However, GPx at Barra (BAR, associated with naval traffic), Gafanha (GAF, harbor and dry-dock activities area), Laranjo (LAR, metal contaminated associated with chlor-alkali plant), and Vagos (VAG, contaminated by polycyclic aromatic hydrocarbons) was significantly lower than the reference site. GST was lower at GAF, Rio Novo do Príncipe (RIO, pulp mill effluent area), LAR, and VAG, whereas GR was lower at RIO. The loss of antioxidant defenses was paralleled by higher LPO levels only at GAF and VAG. However, no DNA integrity loss was found. Results highlight the importance of the adopted multibiomarkers as applied in the liver of L. aurata in coastal water pollution monitoring. The integration of liver antioxidant defense and damage responses can improve the aquatic contamination assessment.

Contamination assessment of a coastal lagoon (Ria de Aveiro, Portugal) using defence and damage biochemical indicators in gill of Liza aurata--an integrated biomarker approach

Fish gill importance in toxicants uptake, bioconcentration and excretion allied to meagre knowledge on branchial damage/protection responses substantiate this study. Five critical sites in Ria de Aveiro (Portugal) were assessed in comparison with a reference site (Torreira), focusing on Liza aurata gill antioxidant defences versus damage (oxidative and genetic). Only in Barra fish displayed damage (lipid peroxidation) though no differences were found in antioxidants. In all other sites, except Rio, antioxidant alterations were found. Thus, fish from Gafanha, Laranjo and Vagos showed higher total glutathione, glutathione peroxidase and catalase. Higher glutathione reductase and glutathione S-transferase activity was also found in the first and the last sites, respectively. In Laranjo, metallothionein levels were higher though lower in Gafanha and Vagos. In general, damage was not accompanied by defences weakening confirming that predicting damage based on antioxidants depletion is not straightforward. The integrated biomarker response index ranked sites as: Gafanha>Barra>Laranjo>Vagos>Rio>Torreira.

Histo-cytological responses of Dicentrarchus labrax (L.) following mercury exposure

This work deals with the damaging effects of mercury (Hg concentrations 251, 355, 501 microgl(-1)) on the structure and ultrastructure of gills, liver, intestine and kidney of farmed European sea bass (Dicentrarchus labrax L., 1758) acutely treated for 24 and 48 h. The histoarchitecture of the gills of exposed fish was highly modified due to severe oedema, telangiectasia and secondary lamellar fusion. In hepatocytes and enterocytes hydropic cell swelling, alterations to the endoplasmic reticulum and mitochondria were noted, in addition to an abundance of myelinoid bodies which were frequently encountered following treatment. In the intestine and renal tubules of exposed European sea bass, rodlet cells (RCs) displayed ultrastructural modifications. Statistical analyses were conducted on the number and the size of selected cell types and structures. Following exposure to mercury for 24 and 48 h, the number of chloride cells, RCs and macrophage aggregates were found to have increased significantly in the gills, the intestine and the head kidney.