Biochemical defense mechanisms against copper-induced oxidative damage in the blue crab, Callinectes sapidus

The evaluations of oxidative stress and neurotoxicity in threatened endemic fish Barbus meridionalis from Osor River (Spain)

Mediterranean barbel (Barbus meridionalis) an endemic species is currently facing habitat destruction and pollution in Osor River (Spain) due to mining runoff that has severely deteriorated the water quality by metals, primarily zinc (Zn). In order to assess the potential risk of metal contamination and hydrological changes in the Osor River by using oxidative stress and neurotoxicity biomarkers via IBR analyses in the barbel, five different stations were chosen: upstream (S1: reference site and S2: hydrologically changed), mine (S3), and downstream (S4 and S5). The highest tissue metal levels were measured particularly at S3 and following downstream sites. SOD activity and the GSH system parameters (GPX, GST, and GSH) were the most sensitive oxidative stress indicators among the antioxidant system parameters. The organs with the greatest changes in antioxidant biomarkers were the liver and gill. As a sign of neurotoxicity, AChE activities significantly raised in the brain and muscle but drastically lowered in the kidney, liver, and gill particularly in the area of mine and downstream compared to reference site. Integrated biomarker response index (IBR) method was applied to visualize the affect of metal and hydrological alterations with biomarker response according to sites in the Osor River. IBR analyzes together with correlations between metal levels and oxidative stress biomarkers, emphasized that S2 and S3 have the greatest impact on the biomarker levels due to mine activity and hydrological changes highlighting the vulnerability to extinction of native fish B. meridionalis. It is also critical to assess the current data based on the multi-biomarker approach for a range of detrimental effects on fish fitness at the individual level as well as population persistence from an ecological standpoint.

Zinc is incorporated into the exoskeleton during post-ecdysial mineralization and inhibits exoskeletal calcification in the blue crab, Callinectes sapidus

Zinc is an essential but toxic metal with both natural and anthropogenic sources. Zinc has been reported to be present in crustacean exoskeleton, but it has remained unknown as to when zinc is incorporated into the shell during the molting cycle and the effects zinc has on exoskeleton properties. This study was conducted to identify a period during the molting cycle, in which zinc is incorporated into the exoskeleton of the blue crab, Callinectes sapidus, and to identify deleterious effects of zinc incorporation on the exoskeleton. It was hypothesized that zinc would be incorporated into the shell during the mineralization phase using calcium transporters, which would inhibit exoskeletal calcification. Post-ecdysial blue crabs were given two injections of zinc in the form of zinc chloride dissolved in Pantin's crustacean saline at the arthrodial membrane at three treatment levels: 0.0, 1.0 and 5.0 µg Zn/g wet weight. Exoskeletal and hemolymph samples were then analyzed for zinc, calcium, and magnesium content. Gill, muscle, and hepatopancreas samples were analyzed for zinc only. Epidermis samples were analyzed for carbonic anhydrase activity. The results showed that the injection dose of 1.0 µg Zn/g wet weight resulted in significant accumulation of zinc in the exoskeleton. There was no significant accumulation of exoskeletal zinc following 5.0 µg Zn/g wet weight injections. A significant reduction in exoskeletal calcium content in crabs treated with 1.0 or 5.0 µg Zn/g wet weight was also observed. The hypothetical model explaining zinc's incorporation into the exoskeleton and inhibition of exoskeletal calcification is proposed. Additionally, for the soft tissues examined, significant zinc accumulation was only observed in the hepatopancreas following zinc treatment. Our data points to the existence of crustacean zinc transporter. This study is the first to present evidence that zinc is deposited to the exoskeleton during post-ecdysial mineralization and inhibits exoskeletal calcification in a crustacean.

Effects of Copper Exposure on Oxidative Stress, Apoptosis, Endoplasmic Reticulum Stress, Autophagy and Immune Response in Different Tissues of Chinese Mitten Crab (Eriocheir sinensis)

High concentrations of copper (Cu²⁺) pose a great threat to aquatic animals. However, the mechanisms underlying the response of crustaceans to Cu²⁺ exposure have not been well studied. Therefore, we investigated the alterations of physiological and molecular parameters in Chinese mitten crab (Eriocheir sinensis) after Cu²⁺ exposure. The crabs were exposed to 0 (control), 0.04, 0.18, and 0.70 mg/L of Cu²⁺ for 5 days, and the hemolymph, hepatopancreas, gills, and muscle were sampled. The results showed that Cu²⁺ exposure decreased the antioxidative capacity and promoted lipid peroxidation in different tissues. Apoptosis was induced by Cu²⁺ exposure, and this activation was associated with the mitochondrial and ERK pathways in the hepatopancreas. ER stress-related genes were upregulated in the hepatopancreas but downregulated in the gills at higher doses of Cu²⁺. Autophagy was considerably influenced by Cu²⁺ exposure, as evidenced by the upregulation of autophagy-related genes in the hepatopancreas and gills. Cu²⁺ exposure also caused an immune response in different tissues, especially the hepatopancreas, where the TLR2-MyD88-NF-κB pathway was initiated to mediate the inflammatory response. Overall, our results suggest that Cu²⁺ exposure induces oxidative stress, ER stress, apoptosis, autophagy, and immune response in E. sinensis, and the toxicity may be implicated following the activation of the ERK, AMPK, and TLR2-MyD88-NF-κB pathways.

Metals and oxidative stress in aquatic decapod crustaceans: A review with special reference to shrimp and crabs

The objective of this review is to synthetize knowledge of the relationship between metals and oxidative stress in aquatic crustaceans (mainly shrimp and crabs) to analyze antioxidant responses when organisms are exposed to metals because the direct metal binding to the active site of enzymes inactivates most of the antioxidant systems. This study reviewed over 150 works, which evidenced that: (i) antioxidant defense strategies used by aquatic decapod crustaceans vary among species; (ii) antioxidant enzymes could be induced or inhibited by metals depending on species, concentration, and exposure time; and (iii) some antioxidant enzymes, as superoxide dismutase increase their activity in low metal levels and time exposures, but their activities are inhibited with higher metal concentrations and exposure time.

Temperature elevation stage-specifically increases metal toxicity through bioconcentration and impairment of antioxidant defense systems in juvenile and adult marine mysids

Metals are of serious concern due to their toxicity, persistency, and accumulation potential in aquatic animals. However, limited information is available on the combined effects of metal with temperature elevation, which is one of the future climate changes suggested for the oceans. In this study, the effect of temperature elevation was investigated by analyzing toxicity, bioconcentration, and antioxidant response in juvenile and adult marine mysids upon exposure to 20 °C and 25 °C for 48 h and 96 h. Based on LC₅₀ values, toxicity of metals was highly reliant on temperature, exposure period, and age. Elevation in temperature significantly increased the whole metal toxicity in juveniles. Bioconcentration was elevated by increasing exposure period and metal concentration. Significant elevation of malondialdehyde (MDA) and depletion of glutathione (GSH) was measured in juveniles, while significant elevation of both MDA and GSH was detected in adults. Subsequently, enzymatic activities of antioxidant enzymes in catalase (CAT) and superoxide dismutase (SOD) increased significantly in adults at 48 h and 96 h, whereas most activities were significantly lowered in juveniles at 96 h. These results suggest that the early life stage of marine mysids is more sensitive to the combined effect of metal and temperature than adult stage due to an impairment in the induction of the antioxidant defense system.

Engineered metal nanoparticles in the marine environment: A review of the effects on marine fauna

There is an increasing awareness of how damaging pollutants in the marine environment can be, however information on the effects of metal engineered nanoparticles (ENPs) on marine biota is still insufficient, despite an exponential rising in related publications in recent years. In order to provide an integrated insight on the present state of the art on metal ENP-related ecotoxicology studies on marine fauna, this review aimed to: (i) highlight the means of toxicity of metal ENPs in the marine environment, (ii) identify the principal biotic and abiotic factors that may alter metal ENP toxicity, and (iii) analyse and categorize results of these studies, including accumulation, molecular and histological biomarkers, genotoxicity and behavioural changes. Data retrieved from Scopus yielded 134 studies that met pre-established criteria. Most often, the target ENPs were titanium, zinc, copper or silver, and most studies (61.2%) focused on the phylum Mollusca. The degree of toxicity of metal ENPs was often dependent on the concentrations tested, length of exposure and the type of tissue sampled. Effects from simple tissue accumulation to DNA damage or behavioural alterations were identified, even when concentrations below environmentally available levels were used. It is proposed that other phyla besides the traditional Mollusca (and within it Bivalvia) should be used more often in this kind of studies, that exact pathways of toxicity be further explored, and lastly that co-stressors be used in order to best mimic conditions observed in nature. In this review, the current knowledge on engineered metal nanoparticles and their effects on marine fauna was summarized, highlighting present knowledge gaps. Guidelines for future studies focusing on under-developed subjects in ENP toxicology are also briefly provided.

Toxic effect of chronic waterborne copper exposure on growth, immunity, anti-oxidative capacity and gut microbiota of Pacific white shrimp Litopenaeus vannamei

Copper can be accumulated in water through excessive sewage discharge or residual algaecide to generate toxic effect to aquatic animals. In this study, the juvenile of Pacific white shrimp, Litopenaeus vannamei was exposed to 0 (control), 0.05, 0.1, 0.2, 0.5 or 1 mg Cu²⁺ L^-1 for 30 days. Growth, immune function, anti-oxidative status and gut microbiota were evaluated. Weight gain and specific growth rate of L. vannamei were significantly decreased with the increase of ambient Cu²⁺. Enlarged lumen and ruptured cells were found in the hepatopancreas of shrimp in the 0.5 or 1 mg Cu²⁺ L^-1 treatment. Total hemocyte counts of shrimp in 0.5 or 1 mg Cu²⁺ L^-1 were significantly lower than in the control. The hemocyanin concentration was also significantly increased in 0.2 or 0.5 mg Cu²⁺ L^-1. Lysozyme contents were reduced in shrimp when Cu²⁺ exceeded 0.2 mg L^-1. Meanwhile, activities of superoxide dismutase and glutathione peroxidase were increased in the hepatopancreas and the activity of Na⁺-K⁺ ATPase was decreased in the gills with increasing Cu²⁺. The mRNA expressions of immune deficiency, toll-like receptor and caspase-3 were all significantly higher in the hepatopancreas in 0.05 mg Cu²⁺ L^-1 than in the control. For the diversity of intestinal microbes, Bacteroidetes significantly decreased in 1 mg Cu²⁺ L^-1 at the phylum level. KEGG pathway analysis demonstrates that 1 mg L^-1 Cu²⁺ can significantly alter metabolism, cellular processes and environmental information processing. This study indicates that the concentration of 1 mg L^-1 Cu can negatively impact growth, hemolymph immunity, anti-oxidative capacity and gut microbiota composition of L. vannamei.

Effects of copper on larvae of the marbled crab Pachygrapsus marmoratus (Decapoda, Grapsidae): Toxicity test and biochemical marker responses

The importance of trace elements in ecotoxicological investigations is a well-known issue when monitoring polluted areas such as commercial harbors. Copper represents one of the most common metal contaminants, often detected in these areas as it is widely employed in various fields and has many sources of inflow in the marine environment. Pachygrapsus marmoratus is a widespread intertidal crab species that has been extensively studied in ecology, ethology and population genetics. Ecotoxicological studies have also been performed, exclusively on the adult stage. In the present study we investigated the mortality and biochemical (oxidative stress and neurotoxicity) responses of P. marmoratus larvae exposure to environmental relevant concentration of copper. Results showed dose-dependent responses in terms of larval mortality, with a calculated LC₅₀ value of 0.5 mg/L of Cu²⁺. The LC₅₀ concentration was used as the starting point for subsequent biochemical response evaluation. Results also demonstrated dose-dependent activation of antioxidant systems assuming a compensatory antioxidant activity to prevent higher cellular damage when larvae were exposed to the highest concentrations of copper. Moreover, a significant enhancement of neurotransmitter activities was observed, assuming a possible direct interaction of copper with the enzymes or an increase of free copper ion aliquot into the cells.

Copper oxide nanoparticles induce the transcriptional modulation of oxidative stress-related genes in Arbacia lixula embryos

Copper oxide nanoparticles (CuO NPs) are widely used in various industrial applications, i.e. semiconductor devices, batteries, solar energy converter, gas sensor, microelectronics, heat transfer fluids, and have been recently recognized as emerging pollutants of increasing concern for human and marine environmental health. Therefore, the toxicity of CuO NPs needs to be thoroughly understood. In this study, we evaluated the potential role of oxidative stress in CuO NP toxicity by exploring the molecular response of Arbacia lixula embryos to three CuO NP concentrations (0.7, 10, 20 ppb) by investigating the transcriptional patterns of oxidative stress-related genes (catalase and superoxide dismutase) and metallothionein, here cloned and characterized for the first time. Time- and concentration-dependent changes in gene expression were detected in A. lixula embryos exposed to CuO NPs, up to pluteus stage (72 h post-fertilization, hpf), indicating that oxidative stress is one of the toxicity mechanisms for CuO NPs. These findings provide new insights into the comprehension of the molecular mechanisms underlying copper nanoparticle toxicity in A. lixula sea urchin and give new tools for monitoring of aquatic areas, thus corroborating the suitability of this embryotoxicity assay for future evaluation of impacted sites.

Sub-lethal effects of waterborne exposure to copper nanoparticles compared to copper sulphate on the shore crab (Carcinus maenas)

The toxicity of soluble copper (Cu) to marine organisms is reasonably well described. However, the hazard of Cu engineered nanomaterial (ENMs) is poorly understood. The aim of the present study was to compare the toxicity of Cu ENMs to Cu as CuSO₄ in the shore crab, Carcinus maenas. The crabs were exposed via the water using a semi-static approach to 0.2 or 1mgL^-1 of Cu ENMs or 1mgL^-1 of Cu as CuSO₄. Gills, hepatopancreas, chela muscle and haemolymph were collected at days 0, 4 and 7 for the body burden of Cu, histology and biochemical analysis [thiobarbituric acid reactive substances (TBARS) and total glutathione (GSH)]. Nominal exposure concentrations of both the ENMs and the metal salt were maintained at over 80% in each treatment throughout the experiment. By day 7, 54% mortality was recorded in the 1mgL^-1 CuSO₄ treatment, compared to just 21% in the 1mgL^-1 Cu ENM-exposed crabs. The target organs for Cu accumulation were similar for both forms of Cu with highest concentrations in the gills, particularly the posterior gills; followed by the hepatopancreas, and with the lowest concentrations in the chela muscle. No changes were observed in the osmolarity of the haemolymph (ANOVA, P>0.05). TBARS were measured as an indicator of lipid peroxidation and showed the greatest change in the anterior and posterior gills and hepatopancreas of animals exposed to 1mgL^-1 Cu ENMs (ANOVA or Kruskal-Wallis, P<0.05). No statistically significant changes in total GSH were observed (ANOVA, P>0.05; n=6 crabs per treatment). Histological analysis revealed organ injuries in all treatments. The types of pathologies observed in the Cu ENM treatments were broadly similar to those of the Cu as CuSO₄ treatment. Overall, the target organs and Cu accumulation from Cu ENMs were comparable to that following exposure to Cu as CuSO₄, and although there were some differences in the sub-lethal effects, the metal salt was more acutely toxic.

Molecular cloning and characterization of a cytoplasmic manganese superoxide dismutase and a mitochondrial manganese superoxide dismutase from Chinese mitten crab Eriocheir sinensis

Superoxide dismutase (SOD) functions as the first and essential enzyme in the antioxidant system and is ubiquitously existed in both prokaryotes and eukaryotes. In the present study, both cytoplasmic and mitochondrial manganese SOD were identified from Chinese mitten crab Eriocheir sinensis (designed as EscytMnSOD and EsmtMnSOD). The complete nucleotide sequence of EscytMnSOD comprised 1349 bp and consisted of a 5' untranslated regions (UTR) of 43 bp, a 3' UTR of 445 bp and an open reading frame (ORF) of 861 bp encoding a polypeptide of 286 amino acid residues. The full-length cDNA sequence of EsmtMnSOD comprised 990 bp, containing a 5' UTR of 55 bp, a 3' UTR of 278 bp and an ORF of 657 bp encoding a polypeptide of 218 amino acid residues. The deduced amino acid sequences of EscytMnSOD and EsmtMnSOD contained highly conserved MnSOD signature and typical functional domain, and exhibited high similarity with their reported homologues. In the phylogenetic tree, EscytMnSOD and EsmtMnSOD were clustered with their homologues from the land crab Cardisoma armatum. The EscytMnSOD and EsmtMnSOD transcripts were constitutively expressed in haemocytes, muscle, heart, gill, haepatopancreas and gonad, with the highest expression level in gills and haepatopancreas, respectively. The mRNA expression levels of them were all up-regulated in haemocytes with similar profiles after the stimulation of Vibrio anguillarum, Micrococcus luteus and Pichia pastoris. The EsmtMnSOD with low basal expression level responded to invading microbes intensely, while the EscytMnSOD with high basal expression level exhibited mild responses against stimulating microbes. The purified rEscytMnSOD and rEsmtMnSOD proteins exhibited specific Mn(2+)-dependent enzymatic activities, while rEscytMnSOD with lower basic activity displayed higher stability than rEsmtMnSOD. All these results indicated that EscytMnSOD and EsmtMnSOD were efficiently antioxidant enzymes and potentially involved in the innate immune responses of E. sinensis with different roles, the former might play a routine role in the innate immune system in crabs, while the later might be involved in the immune response against invading microbes specifically.

The reproductive toxicity on the rotifer Brachionus plicatilis induced by BDE-47 and studies on the effective mechanism based on antioxidant defense system changes

2,2',4,4'-Tetrabromodiphenyl ether (BDE-47), a low-brominated Tetra-BDE that is widely distributed in the marine ecosystem, was selected to investigate the reproductive toxicity on the rotifer, Brachionus plicatilis, and the possible mechanism based on antioxidant defense system changes were studied. The results showed the following: (1) A low concentration of BDE-47 had a slight effect on the egg production of individual females and the egg production rate (EPR) of the population. In fact, BDE-47 exerted reproductive inhibition effects in a time- and concentration-dependent manner. The obtained life tables indicated that BDE-47 at a high concentration prolonged the generation time, whereas low and moderate concentrations of BDE-47 had the opposite effects. BDE-47 at a medium concentration significantly decreased the life expectancy and net reproductive rate (P<0.05). Additionally, a high concentration of BDE-47 markedly decreased the net reproductive rate and intrinsic increase rate (P<0.05). The ultra-structure of the ovary showed that BDE-47 severely damaged the ovary. (2) BDE-47 stress elevated the ROS level in B. plicatilis. The GST activity was induced significantly by the low concentration of BDE-47 and inhibited by the highest concentration tested. The GPx activity and GSH content were significant decreased in all the tested groups, and GR activity was induced. GST and GSH appeared to be sensitive to oxidative stress, and all of the glutathione-related enzymes were found to play an important role in maintaining the antioxidant/pro-oxidant balance based on Pearson's correlation analysis. The results indicated that BDE-47 causes reproductive toxicity in B. plicatilis and that the ROS-mediated pathway is responsible for the observed toxicity.

Future prospects for prophylactic immune stimulation in crustacean aquaculture - the need for improved metadata to address immune system complexity

Future expansion of the crustacean aquaculture industry will be required to ensure global food security. However, this expansion must ensure: (a) that natural resources (including habitat use and fish meal) are sustainably exploited, (b) that the socio-economic development of producing nations is safeguarded, and (c) that the challenge presented by crustacean diseases is adequately met. Conventionally, the problem of disease in crustacean aquaculture has been addressed through prophylactic administration of stimulants, additives or probiotics. However, these approaches have been questioned both experimentally and philosophically. In this review, we argue that real progress in the field of crustacean immune stimulants has now slowed, with only incremental advances now being made. We further contend that an overt focus on the immune effector response has been misguided. In light of the wealth of new data reporting immune system complexity, a more refined approach is necessary - one that must consider the important role played by pattern recognition proteins. In support of this more refined approach, there is now a much greater requirement for the reporting of essential metadata. We propose a broad series of recommendations regarding the 'Minimum Information required to support a Stimulant Assessment experiment' (MISA guidelines) to foster new progression within the field.

The essential oil from Lippia alba induces biochemical stress in the silver catfish (Rhamdia quelen) after transportation

This study investigated the effects of the essential oil (EO) from Lippia alba on biochemical parameters related to oxidative stress in the brain and liver of silver catfish (Rhamdia quelen) after six hours of transport. Fish were transported in plastic bags and divided into three treatments groups: control, 30 µL L- 1 EO from L.alba and 40 µL L-1 EO from L.alba. Prior to transport, the fish were treated with the EO from L. alba (200 µL L -1 for three minutes), except for the control group. Fish transported in bags containing the EO did not have any alterations in acetylcholinesterase, ecto -nucleoside triphosphate diphosphohydrolase and 5'nucleotidase activity in the brain or superoxide dismutase activity in the liver. The hepatic catalase (CAT), glutathione-S-transferase (GST), glutathione peroxidase (GPx), nonprotein thiol and ascorbic acid levels were significantly lower compared to the control group. However, the hepatic thiobarbituric acid- reactive substances, protein oxidation levels and the lipid peroxidation/catalase+glutathione peroxidase (LPO/CAT+GPx) ratio were significantly higher in fish transported with both concentrations of the EO, indicating oxidative stress in the liver. In conclusion, considering the hepatic oxidative stress parameters analyzed in the present experiment, the transport of previously sedated silver catfish in water containing 30 or 40 µL L-1 of EO from L. alba is less effective than the use of lower concentrations.

Effects of fish size on the response of antioxidant systems of Oreochromis niloticus following metal exposures

The size of a fish is an important factor in its physiology, and metal uptake is affected by animal physiology. In this study, small and large tilapias (Oreochromis niloticus) differing approximately twofold in length and fivefold in weight were compared for their antioxidant response. Both groups were exposed to Cu or Cr (1.0 μg/mL) in a freshwater (-80 mg CaCO3/L, conductivity 1.77 mS/cm) using 2 exposure protocols (20 μM for 48 h and 10 μM for 6 days). Following the exposures, the antioxidant enzyme activities (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX; glutathione reductase, GR and glutathione S-transferase, GST) and glutathione (GSH) levels were measured in the liver of fish. Results showed that small fish was affected from exposure conditions much more than large ones as their antioxidant parameters significantly decreased even in controls. Metal exposures of small fish caused significant increases in SOD and CAT activity in acute Cu or Cr exposures. Subchronic Cr exposure of small fish also caused significant increases in CAT, GPx and GST activities, while there was no significant change in Cu-exposed ones. Large fish, however, showed different antioxidant responses as their levels mostly decreased. This study demonstrated that the response of antioxidant system in the liver of tilapia varied in relation to fish sizes and emphasized using different size groups in environmental monitoring and also in evaluation of fish biomarkers.

Amount and metal composition of midgut gland metallothionein in shore crabs (Carcinus maenas) after exposure to cadmium in the food

Accumulation of cadmium in aquatic invertebrates may compromise human food safety and anthropogenic additions of cadmium to coastal areas cause concern. Induction of crustacean metallothionein has been suggested as a useful biomarker for contamination of the aquatic environment with cadmium. We investigated how exposure to low concentrations of cadmium in the food affects the subcellular binding of cadmium with the shore crab Carcinus maenas as model organism. Approximately 80% of the assimilated cadmium was bound in the soluble fraction of the midgut gland and of this, 82% was found in the metallothionein fraction. Metallothionein synthesis was only induced at the highest exposure level. However, the number of cadmium atoms bound per molecule of metallothionein increased linearly with exposure, from approximately 0.18 in the control group to 1.4 in a group administered food containing 5.1 μg Cd g(-1). We noted a marked interaction between the presence of copper and zinc in the midgut gland and the binding of cadmium. The usefulness of crustacean midgut gland metallothionein as a biomarker for cadmium exposure at modest levels was questioned since exposures at levels producing significant increases in the tissue contents of the metal did not result in elevated concentrations of metallothionein in the midgut gland.

Copper resistance selection and activity changes of antioxidases in the flesh fly Boettcherisca peregrina

Natural populations of Boettcherisca (Sarcophaga) peregrina Robineau-Desvoidy (Diptera: Sarcophagidae) were maintained for 20 generations and reared either on unpolluted diet or on polluted diet containing copper at a median lethal concentration (LC50) determined every five generations. This resulted in two reliable strains: the relative susceptible strain (S) and the copperresistant strain (R). The metal accumulation, growth and development, reproduction, and antioxidant enzymes were analyzed in the two strains. The results showed that compared with the S strain, the R strain showed increased metal accumulation and fecundity of female adults. Regardless of whether larvae were fed on diet with or without Cu(2+), the R strain showed higher activity of superoxide dismutase and glutathione S-transferase than the S strain, although without statistical significance. Moreover, the activity of superoxide dismutase and glutathione S-transferase increased when B. peregrina larvae were exposed to Cu(2+) at 100 µg/g but decreased when they were exposed to Cu(2+) at 800 µg/g. Larval catalase activity in the R strain was higher than in the S strain when larvae were fed on diet with or without Cu(2+), although these differences were significant only at the 100 µg/g concentration. Moreover, the activity of catalase decreased when larvae were exposed to experimental Cu(2+). Beyond all expectations, larval glutathione reductase activity was not significantly different between the two strains but changed slightly when larvae were exposed to experimental Cu(2+). These results indicate that copper resistance in B. peregrina larvae is mediated by superoxide dismutase, catalase, and glutathione S-transferase. These results also help in establishing a physiological link between antioxidase activity and the resistance level of B. peregrina to copper.

Modulation of immune-associated parameters and antioxidant responses in the crab (Scylla serrata) exposed to mercury

Organic and inorganic contaminants can suppress immune function in molluscs and crustaceans. It was postulated that metals could modulate immune function in marine crabs. To test this hypothesis, sublethal effects of mercury (Hg) on cellular immune and biochemical responses of crabs were determined. When crabs were exposed for 14 d to environmentally-relevant concentrations of Hg, changes in immune-associated parameters including, total haemocyte count, lysosomal membrane stability, phenoloxidase, super oxide generation and phagocytosis were observed. Oxidative stress, as measured by lipid peroxidation, antioxidant responses, including superoxide dismutase and catalase activities and glutathione-mediated antioxidant enzymes in serum, haemocyte lysate, gills, hepatopancreas and muscle were assessed in crabs exposed to Hg. Exposure to Hg resulted in significantly lesser immune-associated parameters in haemolymph and antioxidants in all tissues studied. Conversely, GST and phenoloxidase activity, were greater in crabs exposed to Hg. Responses of antioxidant parameters (SOD, CAT and GP(x)) were positively correlated with immune responses, including THC, superoxide and phagocytosis. These results were postulated to be due to an immediate response of antioxidant defense to oxygen radicals generated. Overall, the results suggest that 14 d exposure to environmentally realistic concentrations of Hg causes immunomodulation and potentially harmful lessened antioxidant defenses of crabs.

The involvement of metallothionein in the development of aquatic invertebrate

The many documents on metallothioneins (MTs) in aquatic organisms focus especially on their use as biomarkers in environmental monitoring programs, but there are a few papers that summarize the physiological role of MTs in aquatic organisms especially in their development. The multifaceted role of MTs include involvement in homeostasis, protection against heavy metals and oxidant damage, metabolic regulation, sequestration and/or redox control. MTs could be induced by heavy metals which are able to hinder gametogenesis, suppress embryogenesis, and hamper development. Here we pay more attention on the non-essential metal cadmium, which is the most studied heavy metal regarding MTs, and its effects on the development of aquatic invertebrates. In this paper, we have collected published information on MTs in aquatic organisms - mollusks, crustaceans, etc., and summarize its functions in aquatic invertebrates, especially those related to their development.

Efficacy of fentanyl and/or lidocaine on total antioxidants and total oxidants during craniotomy

OBJECTIVE

The aim of this study was to investigate the oxidative, hemodynamic, and analgesic effects of local lidocaine infiltration, or intravenous (IV) fentanyl injection, or a combination of lidocaine and IV fentanyl during head fixation in a 3-pin headrest in patients undergoing elective craniotomy.

DESIGN

Double-blind, randomized, placebo-controlled study.

SETTING

Gaziantep University Medical Faculty, Department of Anesthesiology and Reanimation.

METHODS

Eighty patients were randomly assigned to one of four groups. Five minutes before pin fixation, patients in group L received 1 mg/kg of lidocaine 2% for scalp infiltration (n=20), group F received 1 μg/kg of IV fentanyl (n=20), group FL received 1 mg/kg of lidocaine 2% and 1 μg/kg of fentanyl (n=20), and group P received a placebo (n=20). Following standard anesthesia, basal, pre- and post-fixational hemodynamic data were recorded. Blood samples were taken for evaluation of oxidant and antioxidant levels before and after pin fixation.

RESULTS

The total antioxidant levels after pin fixation were highest in group FL followed by group F, then group L and finally group P (ie, FL>F>L>P) (P<0.05). The mean arterial blood pressure (MAP) after pin fixation was higher than the MAP before pin fixation in groups L and P (P<0.05), but was lower in groups F and FL (P<0.05).

CONCLUSION

The combination of fentanyl and lidocaine before pin fixation is useful in preventing severe hemodynamic response to pain stimuli, such as pin fixation, and in increasing total antioxidant levels in the post-fixational period during craniotomy in adults.

Environmentally induced oxidative stress in aquatic animals

Reactive oxygen species (ROS) are an unenviable part of aerobic life. Their steady-state concentration is a balance between production and elimination providing certain steady-state ROS level. The dynamic equilibrium can be disturbed leading to enhanced ROS level and damage to cellular constituents which is called "oxidative stress". This review describes the general processes responsible for ROS generation in aquatic animals and critically analyses used markers for identification of oxidative stress. Changes in temperature, oxygen levels and salinity can cause the stress in natural and artificial conditions via induction of disbalance between ROS production and elimination. Human borne pollutants can also enhance ROS level in hydrobionts. The role of transition metal ions, such as copper, chromium, mercury and arsenic, and pesticides, namely insecticides, herbicides, and fungicides along with oil products in induction of oxidative stress is highlighted. Last years the research in biology of free radicals was refocused from only descriptive works to molecular mechanisms with particular interest to ones enhancing tolerance. The function of some transcription regulators (Keap1-Nrf2 and HIF-1α) in coordination of organisms' response to oxidative stress is discussed. The future directions in the field are related with more accurate description of oxidative stress, the identification of its general characteristics and mechanisms responsible for adaptation to the stress have been also discussed. The last part marks some perspectives in the study of oxidative stress in hydrobionts, which, in addition to classic use, became more and more popular to address general biological questions such as development, aging and pathologies.

Influences of sex, habitat, and seasonality on heavy-metal concentrations in the burrowing crab (Neohelice granulata) from a coastal lagoon in Argentina

Cadmium, chromium, copper, and manganese concentrations were determined in hepatopancreas of both sexes as well as in eggs at different embryonic development stages of the burrowing crab Neohelice granulata (Brachyura, Varunidae) from Mar Chiquita Coastal Lagoon, a biosphere reserve from Argentina, during a period of 1 year, to assess the bioaccumulation of metals associated with sex and seasonality. Furthermore, metal levels in associated superficial sediment samples were also determined. Two different "cangrejales," one in a mudflat and another one in a salt marsh, were studied. The results showed high concentrations of copper within the hepatopancreas, which was considered a strong reflection of high exposure of N. granulata to this metal. Metal accumulation in hepatopancreas from both study sites and sexes did not present significant differences, as did seasonality. In this sense, both spring and summer metal levels in hepatopancreas were the greatest. Eggs did not present differences in metal accumulation, with the exception of manganese, between sites or between crabs at different embryonic stages. For this metal, eggs from female crabs inhabiting mudflats showed higher levels than those from inhabiting salt marshes. Moreover, eggs in the late embryonic stage also showed the highest manganese concentrations. Metal levels in sediments, however, were similar in both sites. These are the first results of metal level in biota and sediments in this particular environment. Such results could be used as a baseline for the monitoring of metal levels in future studies in Mar Chiquita Coastal Lagoon.

Dietary copper effects in the estuarine crab, Neohelice (Chasmagnathus) granulata, maintained at two different salinities

We analyzed the dietary copper effects in the estuarine crab Neohelice (Chasmagnathus) granulata and its interaction with water salinity. Crabs were maintained at 2 per thousand and 30 per thousand salinity for 5 weeks and they were fed with commercial food supplemented with the green alga Scenedesmus vacuolatus previously exposed to copper. No mortalities were observed, but crabs maintained at 2 per thousand salinity accumulated on average 40% more copper compared to animals maintained at 30 per thousand salinity. At 2 per thousand salinity, superoxide dismutase (SOD) activity and reduced glutathione (GSH) levels were increased at the first and second weeks, respectively, while lipid peroxidation and protein oxidation were evident after 4 weeks of copper exposure. At 30 per thousand salinity, all measured variables increased progressively but were significantly higher only at the end of the assay (5th week), except for protein oxidation that remained unchanged throughout the experiment. The hepatosomatic index (HSI) was significantly decreased in response to copper exposure, but only in crabs acclimated to 2 per thousand. These findings have suggested that dietary copper exposure induces greater metal accumulation and larger oxidative stress responses in crabs maintained at 2 per thousand salinity.

Effects of the 1-alkyl-3-methylimidazolium bromide ionic liquids on the antioxidant defense system of Daphnia magna

This study examined the antioxidant responses of Daphnia magna following exposure to different concentrations of the ionic liquid (IL) 1-octyl-3-methylimidazolium bromide and the 50% LC(50) concentrations of methylimidazolium bromide ILs with different alkyl-chain lengths. Activities of antioxidant defense enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase) and levels of the antioxidant glutathione and the lipid peroxidation by-product malondialdehyde were measured using traditional methods or commercial kits. The concentration and the alkyl-chain length of ILs were found to strongly influence the antioxidant system of D. magna following IL exposure, and exposure to higher IL concentrations and to ILs with longer alkyl chains generally increased the enzyme activities and biomarker levels examined. Therefore, the present study suggests that oxidative stress is involved in the mechanism of IL-induced toxicity in D. magna.

Contaminant effects in shore crabs (Carcinus maenas) from Ria Formosa Lagoon

Defence and damage biomarkers signals were studied in female and male shore crabs Carcinus maenas transplanted between two sites at Ria Formosa Lagoon (South of Portugal). The cross transplantation occurred during 6 days at a hypothetical reference site (Ramalhete), and a contaminated site (Olhão). DNA unwinding technique was used for DNA integrity measurement. General enzymatic antioxidant responses in gills and hepatopancreas (catalase and gills glutathione peroxidase activities increase) showed that cross transplanted crabs (female and male) are suffering from pro-oxidant challenges at the Olhão site. Gills and hepatopancreas glutathione-S-transferase were reduced in both gender crabs transplanted from Ramalhete to Olhão. Metallothioneins induction occurred in crabs transplanted from Ramalhete to Olhão (contaminated by metals and polycyclic aromatic hydrocarbons (PAHs)). However metallothionein differences were also observed towards gender and organ specificities. High gills lipid peroxidation exist in male crabs transplanted from Ramalhete to Olhão, while in females it was the opposite. In both gender crabs from the Olhão site, gills DNA integrity decreased compared to the Ramalhete feral crabs. Moreover, hepatopancreas DNA integrity decreased in male crabs transplanted from Olhão to Ramalhete site which may be related to the environmental conditions (lower contamination levels) revealing the difficulty of selection of reference sites in field studies. Data demonstrated that female and male C. maenas antioxidant defences and damage biomarkers were sensitive to the mixture of contaminants present in these sites as well as good indicators of general stress.

The dynamics of protein and metal metabolism in acclimated and Cd-exposed freshwater crabs (Potamonautes warreni)

Climatic and man-made impacts induced dynamic molecular responses in the South African freshwater crab, Potamonautes warreni. Adult crabs exhibited MT-like protein, binding Cd (0.02micromolg(-1) wet mass+/-0.02), Cu (0.326micromolg(-1) wet mass+/-0.15), and Zn (0.534micromolg(-1) wet mass+/-0.20). The native protein binding Cd, Cu, and Zn showed a respective molecular mass (M) of 9.10kDa+/-1.74, 8.95kDa+/-1.66, and 9.32kDa+/-0.93. With exposure to 0.2mgCd(2+)l(-1) for up to 21 days in 50% of these crabs approximately 90% of Cd was bound to the MT-like protein component (8.54kDa+/-1.64), coinciding with a Zn-bound MT-like component (8.2kDa+/-1.54). Less than 10% were bound in the high M protein component, suggesting a protective function of the protein. In the remaining crabs metals were bound to protein (6.8kDa) with a predominant Cu-binding component.

Oxidative stress biomarkers of exposure in the blood of cichlid species from a metal-contaminated river

The oxidative stress biomarkers of exposure, such as reduced glutathione (GSH), activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) and the levels of lipid peroxidation (LPO), were measured in the blood of three cichlid fish (Oreochromis niloticus, Tilapia rendalli, and Geophagus brasiliensis) taken during two seasons from two sites, unpolluted and polluted by industrial effluents, to evaluate the effectiveness of these biomarkers in assessing the impact of water contamination. The LPO levels in the blood were higher in fish from the metal-contaminated site and the chronic exposure led to significant changes in GPx, CAT, and SOD activities in all three cichlid species. The considerable variation of responses in these cichlids to water contamination evidenced differences in sensitivity to the metal contamination and/or in the potential to respond to it highlighting the importance of using a set of related biomarkers to assess the impact of water contamination.

Metallothionein genes from hydrothermal crabs (Bythograeidae, Decapoda): characterization, sequence analysis, gene expression and comparison with coastal crabs

Hydrothermal vent conditions can alter DNA and hydrothermal organisms may develop detoxification mechanisms and/or genetic adaptations. Hydrothermal vent animals notably synthesize a high quantity of metallothioneins (MT). Recent studies have revealed that the levels of MT within hydrothermal crustacean tissues are higher than those found in other vent animals. To improve our understanding of the environmental impacts exerted on the vent organisms, we characterized the metallothioneins (cDNA and Mt genes) of several members of the Bythograeidae (Bythograea thermydron, Cyanagraea praedator and Segonzacia mesatlantica) which is the only endemic hydrothermal crab family. In comparison, the isolation of metallothionein cDNA was also carried out in several coastal crab families. The results showed that the hydrothermal crabs possess Mt composed of three exons and two introns presenting conserved splicing signals. The cDNA sequences isolated from distinct crabs showed multiple substitutions. In spite of the unique environmental conditions, the protein sequence analysis revealed no specific amino acid residue for the MT of the three hydrothermal crabs. However, gene expression analysis performed by real-time PCR based on S. mesatlantica (hydrothermal crab) compared to Pachygrapsus marmoratus (coastal crab) confirmed the higher metallothionein induction in hydrothermal crabs suggested by others authors.

Cloning and mRNA expression of antioxidant enzymes in the Pacific oyster, Crassostrea gigas in response to cadmium exposure

Cadmium (Cd) is one of the most toxic heavy metal pollutants in the aquatic environment and can induce the formation of reactive oxygen species (ROS) that cause oxidative stress. In present study, we cloned catalase (CAT) and glutathione peroxidase (GPX) cDNA, and investigated its time- and dose-related effects of three Cd concentrations (0.01, 0.05 or 0.1 ppm) on mRNA levels of antioxidant enzymes (superoxide dismutase (SOD), CAT, GPX) in the gill and changes enzyme levels in the hemolymph of the Pacific oyster, Crassostrea gigas. The cDNA indentified encoded proteins of 516 and 244 amino acids corresponding to CAT and GPX, respectively. BLAST analysis from other species indicated that the residues essential to the enzymatic function of CAT and GPX proteins of C. gigas are highly conserved. Cd treatment significantly increased antioxidant enzyme mRNA expression in the gill in a time- and dose-dependent manner. The mRNA expression at 0.1 ppm Cd concentration increased up to 3 days (CAT, GPX) or 7 days (SOD) and then decreased by 7 days (CAT, GPX) or 11 days (SOD). Aspartate aminotransferase, alanine amintransferase and hydrogen peroxide (H(2)O(2)) concentrations levels increased significantly with exposure to 0.05 or 0.1 ppm Cd for 7 days. These results suggest that antioxidant enzymes play important roles in the physiological changes related to metabolism and cell protection that occur in Pacific oysters exposed to Cd.

Effects of cyclic hypoxia on gene expression and reproduction in a grass shrimp, Palaemonetes pugio

Cyclic changes in dissolved oxygen occur naturally in shallow estuarine systems, yet little is known about the adaptations and responses of estuarine organisms to cyclic hypoxia. Here we examine the responses of Palaemonetes pugio, a species of grass shrimp, to cyclic hypoxia (1.5-8 mg/l dissolved oxygen; 4.20-22.42 kPa) at both the molecular and organismal levels. We measured alterations in gene expression in hepatopancreas tissue of female grass shrimp using custom cDNA macroarrays. After short-term (3-d) exposure to cyclic hypoxia, mitochondrial manganese superoxide dismutase (MnSOD) was upregulated and 70-kd heat shock proteins (HSP70) were downregulated. After 7-d exposure, nuclear genes encoding mitochondrial proteins (ribosomal protein S2, ATP synthase, very-long-chain specific acyl-CoA dehydrogenase [VLCAD]) were downregulated, whereas mitochondrial phosphoenol pyruvate carboxykinase (PEP Cbk) was upregulated. After 14 d, vitellogenin and apolipoprotein A1 were upregulated. Taken together, these changes suggest a shift in metabolism toward gluconeogenesis and lipid export. Long-term (77-d) exposure to hypoxia showed that profiles of gene expression returned to pre-exposure levels. These molecular responses differ markedly from those induced by chronic hypoxia. At the organismal level, cyclic hypoxia reduces the number of broods and eggs a female can produce. Demographic analysis showed a lower estimated rate of population growth in grass shrimp exposed to both continuous and short-term cyclic hypoxia, suggesting population-level impacts on grass shrimp.

Environmental stressors (salinity, heavy metals, H2O2) modulate expression of glutathione reductase (GR) gene from the intertidal copepod Tigriopus japonicus

Glutathione reductase (GR) plays an essential role in cell defense against reactive oxygen metabolites by sustaining the reduced status of an important antioxidant, glutathione. To address the effect of oxidative stresses on the intertidal copepod Tigriopus japonicus, we exposed specimens to hydrogen peroxide, heavy metals and different salinity levels, cloned and sequenced the oxidative stress-related GR gene. T. japonicus GR gene (Tigriopus GR) cDNA contained 1526 bp including an open reading frame (ORF) encoding 458 amino acids with a theoretical pI of 6.58 and a calculated molecular weight of 49.6 kDa. Tigriopus GR showed a high similarity to frog Xenopus laevis GR (identity 57%) and the filarial parasite, Onchocerca volvulus GR (identity 57%). Specific motifs such as flavin adenine dinucleotide-binding site (LVLGGGSGGIASARRAAEF), pyridine nucleotide-disulphide oxidoreductases class-I active site (GGTCVNVGCVP), and NADPH binding motif (GxGYIAx18Rx5R) were highly conserved in the deduced amino acid sequence of Tigriopus GR. Interestingly, its expression and enzyme characteristics were different from GR homologue of filarial parasite O. volvulus. To investigate the biochemical and enzymatic characteristics of Tigriopus GR protein, we constructed the expression vector, pCRT7/TOPO NT containing Tigriopus GR. Tigriopus pCRT7/TOPO NT/GR was expressed in Escherichia coli, and the soluble protein was purified by 6x His-tag chromatography. The recombinant Tigriopus GR enzyme was found to make homodimer complexes of approximately 108 kDa on 12% native gel electrophoresis and showed enzymatic activity with NADPH and oxidized glutathione (GSSG) as substrates. To analyze the gene expression of Tigriopus GR against different environmental stresses (hydrogen peroxide, salinity, and heavy metals), we performed real-time reverse transcriptase-polymerase chain reaction (real-time RT-PCR). Slight down-regulation in the expression of Tigriopus GR at the initial stage was observed upon exposure to hydrogen peroxide. The expression recovered in 2h, while there were significant changes upon heavy metal (Cu and Mn) exposures in a time-dependent manner. Also, Tigriopus GR expression was significantly increased with moderately high salt stress (24 and 40 ppt). In the case of low salt stress (0 and 12 ppt) the expression was found to be down-regulated. These findings provide a better understanding of cellular protection mechanisms in the intertidal copepod T. japonicus against the environmental stressors caused by non-optimal salt levels.

Biomarkers of heavy metal contamination in the red fingered marsh crab, Parasesarma erythodactyla

Variation in glutathione antioxidant biochemistry in response to metal contamination and accumulation under field conditions was examined in the brachyurid grapsid, Parasesarma erythodactyla. Significant relationships suggesting accumulation were found between sediment metals and metals in crab tissue for Pb, Cu, Cr, Zn, and Se in males and Cd, Pb, Cr Zn, As, and Se in females. Higher pH and lower organic content were associated with greater uptake of selected metals in males and females. Higher salinity was related to increased metal uptake for Cu and Zn in males and lower salinities to increased Se uptake for males and females. When examining metals, which were elevated in crabs, patterns of site discrimination were similar to sediment metal site discrimination for both males and females. In terms of biochemical responses, glutathione levels remained constant while glutathione peroxidase activity was elevated in individuals where metals were elevated. Only females with the highest levels of accumulated metals exhibited increases in lipid peroxidation products. Glutathione peroxidase activity may be a sensitive biomarker of metal exposure and biological effect and lipid peroxides as a secondary marker when accumulated metals are high.

Metallothionein, antioxidant enzymes and DNA strand breaks as biomarkers of Cd exposure in a marine crab, Charybdis japonica

Cadmium (Cd) is one of the most toxic heavy metals that are widespread in inshore sediments of China, and can induce the production of toxic hydroxyl radicals that cause cell damage. The present study investigated the effect of two Cd concentrations (the final Cd concentration of 0.025 and 0.05 mg/L, prepared with CdCl2 x 2.5H2O) on metallothioneins (MT), antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)) and DNA integrity (DNA strand breaks) for up to 15 days in the gills and hepatopancreas of the portunid crab Charybdis japonica. The result indicated that MT was significantly induced after 3 days, with a dose-response relation between MT contents and Cd concentrations in two tissues and has a time-response relation in hepatopancreas during the experimental period; SOD, CAT and GPx activities could be stimulated after 0.5 day, all attained peak value and then reduced during the experimental period, but were not inhibited at day 15, except SOD and CAT in gills. Gill was more sensitive to Cd than hepatopancreas, and the hepatopancreas was the main detoxification tissue to deal with oxyradicals. DNA strand breaks were induced after 0.5 day, and there was a positive dose-response relation between DNA damage levels and Cd concentrations in gills, rather than hepatopancreas due to higher DNA repair activities. These results suggest the mechanisms of Cd toxicity and detoxification strategies in both tissues of C. japonica; in addition, the use of the biomarkers as indices for biomonitoring potential toxic effect of Cd in situ is discussed.

Synthesis, Spectral, and Biological Properties of Copper(II) Complexes of Thiosemicarbazones of Schiff Bases Derived from 4-Aminoantipyrine and Aromatic Aldehydes

We have synthesized a novel series of Schiff bases by condensation of 4-aminoantipyrine and various aromatic aldehydes followed by reaction with thiosemicarbazide. These thiosemicarbazones are potential ligands toward transition metal ions. The reaction of copper(II) salts with 4[N-(benzalidene)amino]antipyrinethiosemicarbazone (BAAPTS), 4[N-(4′-methoxybenzalidene) amino] antipyrinethiosemicarbozone (MBAAPTS), 4[N-(4′-dimethylamino benzalidene) amino] antipyrinethiosemicarbazone (DABAAPTS), and 4[N-(cinnamalidene) amino] antipyrinethiosemicarbazone (CAAPTS) resulted in the formation of solid complexes with the general composition CuX₂ · (H₂O)(L)(X = Cl, Br,NO₃,NCS, or CH₃COO; L = BAAPTS, MBAAPTS, DABAAPTS, or CAAPTS). These complexes were characterized through elemental analysis, molecular weight, electrical conductance, infrared, electronic spectra, and magnetic susceptibilities at room temperature. Copper(II) complexes with BAAPTS and MBAAPTS were screened for antibacterial and antifungal properties and have exhibited potential activity. Thermal stabilities of two representative complexes were also investigated.

Antioxidant enzyme activities and lipid peroxidation in the freshwater cladoceran Daphnia magna exposed to redox cycling compounds

Contaminant-related changes in antioxidative processes in the freshwater crustacea Daphnia magna exposed to model redox cycling contaminant were assessed. Activities of key antioxidant enzymes including catalase, superoxide dismutase, glutathione peroxidase and glutathione S-transferases and levels of lipid peroxidation measured as thiobarbituric acid-reactive substances (TBARS) and lipofucsin pigment content were determined in D. magna juveniles after being exposed to sublethal levels of menadione, paraquat, endosulfan, cadmium and copper for 48 h. Results denoted different patterns of antioxidant enzyme responses, suggesting that different toxicants may induce different antioxidant/prooxidant responses depending on their ability to produce reactive oxygen species and antioxidant enzymes to detoxify them. Low responses of antioxidant enzyme activities for menadione and endosulfan, associated with increasing levels of lipid peroxidation and enhanced levels of antioxidant enzyme activities for paraquat, seemed to prevent lipid peroxidation, whereas high levels of both antioxidant enzyme activities and lipid peroxidation were found for copper. For cadmium, low antioxidant enzyme responses coupled with negligible increases in lipid peroxidation indicated low potential for cadmium to alter the antioxidant/prooxidant status in Daphnia. Among the studied enzymes, total glutathione peroxidase, catalase and glutathione S-transferase appeared to be the most responsive biomarkers of oxidative stress.

The effects of cadmium in feed, and its amelioration with zinc, on element balances in sheep1

The effects of feeding Cd to sheep at a level that is typical of polluted regions were investigated, as well as possible amelioration by adding Zn to the diet. Welsh Mountain ewes (n = 24) were fed herb-age and concentrate in metabolism crates, with four supplement treatments in a two-factor factorial design: no supplement, Cd supplement only, Zn supplement only, and a combination of both the Cd and Zn supplement. Cadmium (286 microg/kg of feed DMI) and Zn (8.6 mg/kg feed DMI) were added as sulfates. Food and water intakes and element balances were recorded over 20 d after 7 d dietary adaptation, and element concentrations were determined in wool samples. Neither metal affected DMI or digestibility (P > 0.15), but water intake (P = 0.001) and urine output (P = 0.03) were decreased when only the Zn supplement was added. Water retention was increased by the Cd supplement (P = 0.04). In wool, the Cd supplement greatly increased the K concentration if no Zn supplement was fed (P = 0.02), and the Zn supplement decreased Mn concentration (P = 0.02). Cadmium in feed increased the Cd balance and produced several mineral disturbances, in particular a decrease in Na balance that is typical of renal tubular disorders. Adding Zn as well as Cd to feed returned the Cd balance to a level similar to that of sheep receiving neither Cd nor Zn, which suggests that Zn status is critical in determining whether Cd in feed increases the Cd balance in sheep. Feeding Cd also increased urinary K, Fe, Mo, Cr, B, and Ca concentrations, even when supplementary Zn was fed. It is concluded that low levels of Cd in sheep feed can increase the Cd balance if adequate Zn is not provided, which can lead to subclinical mineral disturbances and changes in the mineral concentrations in wool.

Replacement of a cytosolic copper/zinc superoxide dismutase by a novel cytosolic manganese superoxide dismutase in crustaceans that use copper (haemocyanin) for oxygen transport

The blue crab, Callinectes sapidus, which uses the copper-dependent protein haemocyanin for oxygen transport, lacks the ubiquitous cytosolic copper-dependent enzyme copper/zinc superoxide dismutase (Cu,ZnSOD) as evidenced by undetectable levels of Cu,ZnSOD activity, protein and mRNA in the hepatopancreas (the site of haemocyanin synthesis) and gills. Instead, the crab has an unusual cytosolic manganese SOD (cytMnSOD), which is retained in the cytosol, because it lacks a mitochondrial transit peptide. A second familiar MnSOD is present in the mitochondria (mtMnSOD). This unique phenomenon occurs in all Crustacea that use haemocyanin for oxygen transport. Molecular phylogeny analysis suggests the MnSOD gene duplication is as old as the origin of the arthropod phylum. cytMnSOD activity in the hepatopancreas changes during the moulting cycle of the crab. Activity is high in intermoult crabs and non-detectable in postmoult papershell crabs. mtMnSOD is present in all stages of the moulting cycle. Despite the lack of cytCu,ZnSOD, crabs have an extracellular Cu,ZnSOD (ecCu,ZnSOD) that is produced by haemocytes, and is part of a large, approx. 160 kDa, covalently-linked protein complex. ecCu,ZnSOD is absent from the hepatopancreas of intermoult crabs, but appears in this tissue at premoult. However, no ecCu,ZnSOD mRNA can be detected, suggesting that the protein is recruited from the haemolymph. Screening of different taxa of the arthropod phylum for Cu,ZnSOD activity shows that those crustaceans that use haemoglobin for oxygen transport have retained cytCu,ZnSOD. It appears, therefore, that the replacement of cytCu,ZnSOD with cytMnSOD is part of an adaptive response to the dynamic, haemocyanin-linked, fluctuations in copper metabolism that occur during the moulting cycle of the crab.

The mode of action of acute and chronic concentrations of waterborne Cd in the digestive gland of the acclimated infested freshwater crab ( Potamonautes warreni)

Cadmium (Cd) uptake, transport and accumulation were investigated in the digestive gland of the freshwater crab, Potamonautes warreni, acclimated in its natural habitat to stresses, such as microbial gill infestations, Cd(2+) and NH(4)(+), and subsequently exposed to increasing concentrations of Cd in the laboratory for up to 21 days. Cd exposure (0.2 mg l(-1)) for 7-14 days led to Cd permeating cell membranes in a particulate form; it was adsorbed intracellularly to endocytotic circulating amoebocytes, lipid droplets and Golgi vesicles in R-cells. Cd also caused dissociation of the fibrillar rough endoplasmic reticulum (RER) and an increase in phagocytotic activity in F- and B-cells. After 21 days, Cd accumulated as crystal deposits on the basal membranes of cells in the haemolymph space and along the microvilli of cells lining the tubular lumen. Elevated Cd concentrations were found in the cytosol, amoebocytes, Golgi vesicles and P/Ca granules in R-cells. Chronic exposure to higher concentrations of Cd (0.5 and 1.0 mg l(-1)) increased crystal deposition, whereas concentrations of Cd, copper and iron decreased in the cell membranes and in amoebocytes and increased in Golgi vesicles. Reduced lipid content, swollen nuclei with vesiculated nucleoli and enhanced activity of RER in R-cells were also noted. Cd was stored in the P/Ca and Ca granules of B-cells. Acute exposure to Cd (2.0 mg l(-1) for 48 h) caused metal granule accumulation along cells lining the tubular lumen and cellular dissociation, with acidosis and necrosis in the cytoplasm and Cd deposits in mitochondria. Cd accumulated in the cells of the digestive gland in a time-, concentration- and cell-type-specific fashion.

Cu,Zn superoxide dismutase in Rhodotorula and Udeniomyces spp. isolated from sea water: cloning and sequencing the encoding region

The gene encoding the copper-zinc superoxide dismutase enzyme (SODC or Cu,Zn-SOD) has been cloned from several species of higher eukaryotes, but superoxide dismutase genes from moulds and yeast have not been studied extensively. Only 15 nucleotide sequences have been reported in the SwissProt, EMBL and GenBank data libraries. In general the presence of Cu,Zn-SOD in cytosol, as well as Mn-SOD in the mitochondrial matrix of yeast, has been accepted. The absence of Cu,Zn-SOD in a pigmented yeast has been accepted as a general rule. Some authors suggest that the absence of Cu,Zn-SOD in pigmented yeast is complemented by the presence of carotenoproteins that act as an extra mitochondrial antioxidant. In this report, we found that the absence of SODC is not a rule for pigmented yeast: Udeniomyces puniceus expresses an active SODC which responds to Cu(2+) induction, as has been reported previously for non-pigmented yeast. The encoding region of the sod1 gene was cloned from three species of pigmented marine yeast thorough genomic DNA PCR amplification. Fragments of 485-487 nucleotides were obtained, which contain information for theoretical products of 153-154 amino acids. In Rhodotorula mucilaginosa the deduced amino acid sequence shows that insertion of three bases (C(112), A(149) and C(166)) generates a stop codon at position 123 (TGA). For Rhodotorula graminis a single change (T for A) generates a stop codon at position 298. For both species, this non-transcription of encoding sequence correlates with the absence of peptides or active proteins in cell homogenates. For U. puniceus, the cloned nucleotide sequence contains all necessary information to produce a functional protein, which correlates with activity detected in cell homogenates, both under normal conditions and by copper induction experiments. Finally, we clearly showed that the key factor in protection against oxidative stress on pigmented yeast is related not only to the presence of protective pigments but also to their amounts and spectra, as well as the presence and activity of SODC.

Identification of 100 KDa protein in sera of mice-treated with Cu(II) complex with superoxide dismutase-mimetic activity

The protein profile of sera isolated from mice pre-treated with Cu(II) complex of Girard T with superoxide dismutase (SOD)-mimetic activity was analyzed using SDS-PAGE. This complex was intraperitoneally administered (10 mg/Kg body weight) to Swiss albino mice. The resolved polypeptides showed a new sharp band at 100 KDa against which a polyclonal antibody was raised in rabbit. Sera of rabbit anti-100 KDa protein was used as a powerful probe for the detection of 100 KDa protein isolated from sera of treated mice. Western blot assays revealed a strong reactive polypeptide band at 100 KDa in sera of the mice, but no cross reaction was observed with sera of normal mice. The identification of purified polypeptide was confirmed by different characterization experiments.

Response of antioxidant systems to copper in the gills of the clam Ruditapes decussatus

Copper (Cu) is an essential element for biological systems, however, when present in excess, is toxic. Metallothioneins can play an important role in Cu homeostasis and detoxification. Moreover, Cu can catalyse the production of toxic hydroxyl radicals that cause lipid peroxidation but defence systems in the cells can limit the oxidative damage. The present study was performed to investigate the effect of three Cu concentrations (0.5, 2.5 and 25 microg l(-1)) on the response of antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathion peroxidase and total glutathion peroxidase), total proteins, metallothioneins (MT), malondialdehyde (MDA) concentrations in the gills of the clam, Ruditapes decussatus. The activity of antioxidant enzymes and total proteins, MT and MDA concentrations were measured in the gills of the clams after 1, 3, 7, 14, 21 and 28 days of Cu exposure. Results indicate that Cu only induces an imbalance in the oxygen metabolism during the first week of Cu exposure due to a decrease in mitochondrial SOD and CAT, selenium-dependent and total glutathion peroxidase activities. Cu also causes lipid peroxidation, measured by the MDA formation, that was Cu dependent. In the gills of clams exposed to 25 microg Cu/l, the excess of Cu triggers the induction of MT synthesis after 3 days of exposure.

Relating the reproductive toxicity of five ingested metals in calanoid copepods with sulfur affinity

The sublethal toxicity of dietary Ag, Cd, Hg, Mn, and Zn to marine copepods, measured as depressed egg production, was evaluated as a function of ambient metal concentrations and metal concentrations in copepod tissues. All metals were toxic following 4-h feedings on metal-contaminated phytoplankton food, but there was a four order of magnitude difference between the inhibitory concentration in copepod tissues of the most toxic (2.4 nmol g(-1) dry wt. for Hg) and least toxic (13.4 micromol g(-1) dry wt. for Mn) metals. Metal concentrations in copepods that elicited a toxic response were about 3 times higher than background concentrations for Ag and 9 times higher for Hg, about 2 times higher for Cd, two orders of magnitude higher for Mn, and only 5% higher for Zn. Copepods exposed to lower concentrations of Zn for longer periods (1 week), resulting in tissue Zn concentrations similar to those in the short-term exposures, were not affected, suggesting that copepods were capable of adjusting to slowly increasing Zn by sequestration of this metal. Toxic metal concentrations in copepod tissues were directly proportional (r2 = 0.85) to the affinity of the metals for sulfur, as indicated by the solubility products of the metal sulfides. This relationship, together with protein analysis of eggs, published recently, suggests that metals affect egg production by binding to enzymes involved with vitellogenesis.