Acute Copper Exposure Research Articles

Metabolic responses of golden trout (Oncorhynchus mykiss aguabonita) after acute exposure to waterborne copper.

Despite the broad knowledge of copper-induced stress and toxicity, data on the physiological responses to acute copper exposure and the correlation of those activities to a generalized stress response are still limited. The present study aimed to assess the physiological responses of golden trout to overcome copper stress at concentrations of 60µg/L and 120µg/L after 96h, respectively. The activities of glucose-6-phosphate dehydrogenase (G6PD) phosphoenolpyruvate carboxykinase (PEPCK) and NADPH/NADP+ ratio were significantly increased, and metabolites including glucose 6-phosphate, fructose 1-phosphate and fatty acids significantly accumulated in fish liver, indicating that gluconeogenesis, the pentose-phosphate pathway, as well as alteration of the membrane fatty acid composition were activated to serve as a defense mechanism against 60µg/L of copper after 96h. After exposure to 120µg/L of copper for 96h, the NAD+ and ATP contents, the activities of enzymes in the glycolytic pathway (phosphofructokinase, PFK and pyruvate kinase, PK) and mitochondrial respiratory chain complex I decreased significantly in fish liver. In addition, carbohydrates and MDA accumulated in golden trout after 120µg/L copper treatment. These results indicated that 120µg/L of copper exposure may induce a metabolic stress in golden trout after 96h. The multi-marker approach allows us to reach a greater understanding of the effects of copper on physiological responses of golden trout.

Short communication: Effects of acute copper exposure on ionic regulation of the freshwater crab Aegla castro

Aeglids are unique freshwater decapods whose habitats are being impacted by metallic compounds, such as copper (Cu). Thus, we investigated the effects of acute Cu exposure on ionic regulation of Aegla castro. For this, male specimens in intermolt were collected from a reference stream and acclimated for 5 days in laboratory. After which, crabs were exposed to 11 μg L−1 Cu (Cu11) or only to water (CTR) for 24 h. Hemolymph samples were withdrawn for the determination of Na+, K+, Ca2+, and Mg2+ concentrations and the posterior gills removed for the analysis of Na+/K+-ATPase, Ca2+-ATPase, H+-ATPase, and carbonic anhydrase (CA) activities. Increased Ca2+ and Mg2+ hemolymph concentrations were observed in animals from Cu11, when compared with CTR group. In addition, decreased activity of CA was observed in animals exposed to Cu. In the current study, alterations in Ca2+ and Mg2+concentrations probably indicate that animals activated exoskeleton reabsorption mechanisms, characteristic of the premolt. Therefore, increased Ca2+ and Mg2+ concentrations in hemolymph may indicate that a biochemical signal associated with the molting cycle was triggered by Cu exposure. Despite the known harmful effects of Cu on osmoregulatory enzymes, here we observed decreased activity only in CA. However, decreased activity of CA could trigger both acid-base imbalance and ionic disruption, since CA provides H+ and HCO3− for intracellular pH maintenance, and underpins Na+ and Cl− for ionic regulation. Therefore, understanding how aeglids respond to metal contamination in laboratory conditions is crucial to assess their potential as an alternative biological model for aquatic ecotoxicology.

Alleviative effects of dietary microbial floc on copper-induced inflammation, oxidative stress, intestinal apoptosis and barrier dysfunction in Rhynchocypris lagowski Dybowski

The heavy metal poisoning in humans and fish represents a significant global problem. Copper (Cu), as an essential micronutrient in human and animal metabolism, often accumulates excessively in aquatic environment. The microbial floc is rich in a variety of probiotics and bioactive compounds, which has been documented to have the functions of antioxidant and immunoenhancement. A 64-day experiment was conducted to investigate the protective effects and potential mechanisms of dietary supplementation of microbial floc and Cu exposure on inflammatory response, oxidative stress, intestinal apoptosis and barrier dysfunction in Rhynchocypris lagowski Dybowski. A total of four hundred fifty R. lagowski were fed five experimental diets containing graded levels of microbial floc from 0% to 16% (referred to as B0, B4, B8, B12 and B16, respectively) in the first 60 days, and 96 h of acute copper exposure test was carried out in the last four days. The results showed that microbial floc exerted significant alleviative effects by preventing alterations in the levels of bioaccumulation, caspase3, caspase8, caspase9, malondialdehyde and interleukin-6, improving the activities of lysozyme, complement C3, complement C4, immunoglobulin M, alkaline phosphatase, heat shock protein 70, heat shock protein 90 and glutathione peroxidase, catalase, superoxide dismutase, total antioxidant capacity. In addition, microbial floc assisted in regulating the expression of NF-κB/Nrf2 signaling molecule genes, including NF-κB, TNF-α, IL-1β, IL-8, IL-10, TGF-β, Keap1, Nrf2, Maf, HO-1, CAT, CuZn-SOD, GCLC and GPX. Overall, our results suggest that dietary supplementation with of microbial floc can alleviate copper-induced inflammation, oxidative stress, intestinal apoptosis and barrier dysfunction in R. lagowski. A suitable supplementation level of approximately 12% microbial floc is recommended in the present study.

Alternative splicing is highly variable among Daphnia pulex lineages in response to acute copper exposure

BackgroundDespite being one of the primary mechanisms of gene expression regulation in eukaryotes, alternative splicing is often overlooked in ecotoxicogenomic studies. The process of alternative splicing facilitates the production of multiple mRNA isoforms from a single gene thereby greatly increasing the diversity of the transcriptome and proteome. This process can be important in enabling the organism to cope with stressful conditions. Accurate identification of splice sites using RNA sequencing requires alignment to independent exonic positions within the genome, presenting bioinformatic challenges, particularly when using short read data. Although technological advances allow for the detection of splicing patterns on a genome-wide scale, very little is known about the extent of intraspecies variation in splicing patterns, particularly in response to environmental stressors. In this study, we used RNA-sequencing to study the molecular responses to acute copper exposure in three lineages of Daphnia pulex by focusing on the contribution of alternative splicing in addition to gene expression responses.ResultsBy comparing the overall gene expression and splicing patterns among all 15 copper-exposed samples and 6 controls, we identified 588 differentially expressed (DE) genes and 16 differentially spliced (DS) genes. Most of the DS genes (13) were not found to be DE, suggesting unique transcriptional regulation in response to copper that went unnoticed with conventional DE analysis. To understand the influence of genetic background on gene expression and alternative splicing responses to Cu, each of the three lineages was analyzed separately. In contrast to the overall analysis, each lineage had a higher proportion of unique DS genes than DE genes suggesting that genetic background has a larger influence on DS than on DE. Gene Ontology analysis revealed that some pathways involved in stress response were jointly regulated by DS and DE genes while others were regulated by only transcription or only splicing.ConclusionsOur findings suggest an important role for alternative splicing in shaping transcriptome diversity in response to metal exposure in Daphnia, highlighting the importance of integrating splicing analyses with gene expression surveys to characterize molecular pathways in evolutionary and environmental studies.

Bioflocs protects copper-induced inflammatory response and oxidative stress in Rhynchocypris lagowski Dybowski through inhibiting NF-κB and Nrf2 signaling pathways

Copper (Cu) is an essential element in the metabolic process of humans and animals, but it can cause toxicity at high concentrations of exposure. Bioflocs has been proved to have antioxidant, immune-enhancing and anti-inflammatory properties. Here, the purpose of this study was to evaluate potential mechanisms and protective effects of bioflocs and Cu exposure on inflammatory response, oxidative stress and immune-related genes and protein expression in Rhynchocypris lagowski Dybowski. 360 healthy R. lagowski were irregularly distributed among 12 tanks (3 tanks per group, 30 fish per tank). The experiment was divided into two parts: the feeding experiment was carried out in the first eight weeks, followed by acute copper exposure for 96 h. Then we selected the stressed fish for experimental analysis. The results provided evidences that bioflocs protected the R. lagowski by inhibiting the accumulation of copper, the activity of immune enzymes and the expression of NF-κB signaling pathway related genes and proteins, and the activity of antioxidant enzymes and the expression of Nrf2 signaling pathway related genes. Overall, these findings suggest that bioflocs could regulate the activation of Nrf2 and protect acute copper exposure induced inflammatory response by inhibiting the NF-κB signaling pathway in R. lagowski.

Changes on plasmatic electrolytes and behavior of freshwater fish, Luciobarbus bocagei, as a function of acute copper exposure

Copper is continuously increasing in water and its toxic effects on aquatic organisms arise, among others, from biochemical interactions. In Northeastern Portugal, different watercourses are suffering negative impacts, namely in the Portelo stream, affected by collapse and continuous input of mining deposits, including Cu content. Therefore, the impact of sub-lethal Cu concentrations on fish Na+, K+ and Ca2+ plasma concentrations was evaluated to assess osmoregulatory adverse effects. Also, the same evaluations were conducted after fish were changed to clean water, to assess fish ability to revert electrolytes levels. Acute toxicity tests were conducted, using barbels (Luciobarbus bocagei) under two different copper concentrations. Fish behavior and Condition Factor (K) were also evaluated. Barbels under Cu exposition showed several changes at physiological and behavioral levels, such as ion imbalance, lowere aerobic scope and mortality and reduced K. According to our results, plasma K+ and Ca2+ levels may increase, while Na+ levels may decrease in fish exposed to Cu, allowing fish to an osmotic adjustment and reduced susceptibility to Cu, in an attempt to survive under environmental stress. Under the conditions of these experiments, fish also showed a capacity to reverse levels of electrolytes, when they cease to be exposed to Cu; however, that depends upon exposure concentration.

Assessment of Cu sub-lethal toxicity (LC50) in the cold-water gorgonian Dentomuricea meteor under a deep-sea mining activity scenario

Previous aquaria-based experiments have shown dissolution and leaching of metals, especially copper (Cu), from the simulated sediment plumes generated during mining activities resulting in a pronounced increase of Cu contamination in the surrounding seawater. Metals are bioavailable to corals with food, through ingestion (particulate phase) and through tissue-facilitated transport (passive diffusion). With corals being particularly vulnerable to metal contamination, resuspension of metal-bearing sediments during mining activities represents an important ecological threat. This study was undertaken to evaluate the impact of acute copper exposure (LC50;96 h) on the survival of the cold-water octocoral Dentomuricea aff. meteor. The experimental design was divided in two stages. In stage one, a Cu range-finding toxicity test was performed using Cu dilutions in filtered seawater with concentrations of 0 (control); 60; 150; 250; 450; 600 μg/L. Coral mortality was investigated visually based on the percent surface area of tissue changing from natural yellow colour to black colour indicative of tissue necrosis and death. In stage two, we used the results obtained in the range-finding experiment, to define sub-lethal Cu exposure treatments and exposed D. meteor to Cu concentration of 0 (control); 50; 100; 150; 200; 250 μg/L for 96 h. The corals physical conditions were inspected daily and seawater conditions recorded. Corals were considered dead when all of their tissue turned black. The LC50 value was calculated with regression analysis following Probits methodology. Our results indicate that Cu LC50;96 h for the octocoral D. meteor is 137 μg/L.

Time does matter! Acute copper exposure abolishes rhythmicity of clock gene in Danio rerio

The circadian clock is a key cellular timing system that coordinates physiology and behavior. Light is a key regulator of the clock mechanism via its activation of Per and Cry clock gene expression. Evidence points to a key role of reactive oxygen species (ROS) in resetting this process. In this context, the aim of the present study was to explore copper as a ROS generator, using an innovative approach investigating its effects on circadian timing. Liver and brain from Danio rerio specimens exposed to 0, 5, 25 and 45 μg/L copper concentrations were obtained. Daily oscillations of superoxide dismutase (SOD) and catalase (CAT) enzymatic activity and their correlations both with clock genes (per1, per2, and cry1a) and with organism energy cost were determined. CAT expression correlates with per2 and cry1a and, thus, provides data to support the hypothesis of hydrogen peroxide production by a phototransducing flavin-containing oxidase. Higher SOD activity is correlated with higher intracellular ATP levels. Copper disturbed the daily oscillation of antioxidant enzymes and clock genes, with disturbed per1 rhythmicity in both the brain and liver, while cry1a rhythmicity was abolished in the liver at 25 μg/L copper. Coordination between the SOD and the CAT enzymes was lost when copper concentrations exceeded the limits established by international laws. These results indicate that organism synchronization with the environment may be impaired due to acute copper exposure.

Effects of Acute Copper Exposure on Physiological and Cytological Responses in Liver of GIFT Tilapia (Oreochromis niloticus)

This study was designed to evaluate the physiological and cytological responses in liver of GIFT tilapia (Oreochromis niloticus) to acute copper exposure. Fish were exposed to three Cu treatments at the following concentrations: 0 (control), 1.96 mg/L and 3.92 mg/L, and liver samples were collected after 96h of exposure. Observation of oil red O staining showed that acute copper exposure increased lipid accumulation in liver, which may due to changes of hepatic enzyme activities (malic enzyme, lipoprotein lipase, hepatic lipase, fatty acid synthetase, carnitine palmitoyltransferases l) and lesions of some organelles such as mitochondria and swollen rough endoplasmic reticulum of hepatocytes. This study indicated that acute copper exposure induced hepatic lipid metabolic disturbances and damaged hepatic organelle in GIFT tilapia.

Hydrostatic pressure and temperature affect the tolerance of the free-living marine nematode Halomonhystera disjuncta to acute copper exposure

Potential deep-sea mineral extraction poses new challenges for ecotoxicological research since little is known about effects of abiotic conditions present in the deep sea on the toxicity of heavy metals. Due to the difficulty of collecting and maintaining deep-sea organisms alive, a first step would be to understand the effects of high hydrostatic pressure and low temperatures on heavy metal toxicity using shallow-water relatives of deep-sea species. Here, we present the results of acute copper toxicity tests on the free-living shallow-water marine nematode Halomonhystera disjuncta, which has close phylogenetic and ecological links to the bathyal species Halomonhystera hermesi. Copper toxicity was assessed using a semi-liquid gellan gum medium at two levels of hydrostatic pressure (0.1MPa and 10MPa) and temperature (10°C and 20°C) in a fully crossed design. Mortality of nematodes in each treatment was assessed at 4 time intervals (24 and 48h for all experiments and additionally 72 and 96h for experiments run at 10°C). LC50 values ranged between 0.561 and 1.864mg Cu2+L−1 and showed a decreasing trend with incubation time. Exposure to high hydrostatic pressure significantly increased sensitivity of nematodes to copper, whereas lower temperature resulted in an apparently increased copper tolerance, possibly as a result of a slower metabolism under low temperatures. These results indicate that hydrostatic pressure and temperature significantly affect metal toxicity and therefore need to be considered in toxicity assessments for deep-sea species. Any application of pollution limits derived from studies of shallow-water species to the deep-sea mining context must be done cautiously, with consideration of the effects of both stressors.

The Effects of Temperature and Hydrostatic Pressure on Metal Toxicity: Insights into Toxicity in the Deep Sea

Mineral prospecting in the deep sea is increasing, promoting concern regarding potential ecotoxicological impacts on deep-sea fauna. Technological difficulties in assessing toxicity in deep-sea species has promoted interest in developing shallow-water ecotoxicological proxy species. However, it is unclear how the low temperature and high hydrostatic pressure prevalent in the deep sea affect toxicity, and whether adaptation to deep-sea environmental conditions moderates any effects of these factors. To address these uncertainties we assessed the effects of temperature and hydrostatic pressure on lethal and sublethal (respiration rate, antioxidant enzyme activity) toxicity in acute (96 h) copper and cadmium exposures, using the shallow-water ecophysiological model organism Palaemon varians. Low temperature reduced toxicity in both metals, but reduced cadmium toxicity significantly more. In contrast, elevated hydrostatic pressure increased copper toxicity, but did not affect cadmium toxicity. The synergistic interaction between copper and cadmium was not affected by low temperature, but high hydrostatic pressure significantly enhanced the synergism. Differential environmental effects on toxicity suggest different mechanisms of action for copper and cadmium, and highlight that mechanistic understanding of toxicity is fundamental to predicting environmental effects on toxicity. Although results infer that sensitivity to toxicants differs across biogeographic ranges, shallow-water species may be suitable ecotoxicological proxies for deep-sea species, dependent on adaptation to habitats with similar environmental variability.

Characterization and response of antioxidant systems in the tissues of the freshwater pond snail (Lymnaea stagnalis) during acute copper exposure

The response of enzymatic (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX and glutathione reductase, GR) and non-enzymatic responses (glutathione, GSH, oxidized glutathione, GSSG and GSH/GSSG) against acute Cu toxicity (2–90μg/mL for 48h) in different tissues of Lymnaea stagnalis were measured. Incubation conditions for enzymatic activity measurements were optimized for L. stagnalis tissues. Three examined tissues, the hepatopancreas, the foot muscle and the mantle, exhibited variable responses in antioxidant parameters as a function of Cu concentrations. The most responsive antioxidant enzymes were GPX and CAT while GR appeared less sensitive. In general antioxidant enzymes at higher Cu concentrations though GSH levels at lower Cu concentrations exhibited the greatest changes in hepatopancreas and foot muscle, respectively. All antioxidant enzymes except GR increased after exposure to the highest Cu concentration in mantle. Total and reduced GSH increased in hepatopancreas but decreased with GSH/GSSG ratios at all Cu concentrations in foot muscle. The present results show that antioxidants respond to acute Cu exposure at concentrations as low as 2μg Cu/L in adult L. stagnalis with variable responses in different tissues. Antioxidants both including enzymatic and non-enzymatic parameters may account, in part, for the high tolerance to acute metal exposure observed in adult L. stagnalis and could form suited biomarkers to evaluate the metal exposure and toxicity in aquatic environment even at relatively low level short term exposure.

Quantifying Fish Swimming Behavior in Response to Acute Exposure of Aqueous Copper Using Computer Assisted Video and Digital Image Analysis

Behavioral responses of aquatic organisms to environmental contaminants can be precursors of other effects such as survival, growth, or reproduction. However, these responses may be subtle, and measurement can be challenging. Using juvenile white sturgeon (Acipenser transmontanus) with copper exposures, this paper illustrates techniques used for quantifying behavioral responses using computer assisted video and digital image analysis. In previous studies severe impairments in swimming behavior were observed among early life stage white sturgeon during acute and chronic exposures to copper. Sturgeon behavior was rapidly impaired and to the extent that survival in the field would be jeopardized, as fish would be swept downstream, or readily captured by predators. The objectives of this investigation were to illustrate protocols to quantify swimming activity during a series of acute copper exposures to determine time to effect during early lifestage development, and to understand the significance of these responses relative to survival of these vulnerable early lifestage fish. With mortality being on a time continuum, determining when copper first affects swimming ability helps us to understand the implications for population level effects. The techniques used are readily adaptable to experimental designs with other organisms and stressors.

Quantifying Fish Swimming Behavior in Response to Acute Exposure of Aqueous Copper Using Computer Assisted Video and Digital Image Analysis.

Behavioral responses of aquatic organisms to environmental contaminants can be precursors of other effects such as survival, growth, or reproduction. However, these responses may be subtle, and measurement can be challenging. Using juvenile white sturgeon (Acipenser transmontanus) with copper exposures, this paper illustrates techniques used for quantifying behavioral responses using computer assisted video and digital image analysis. In previous studies severe impairments in swimming behavior were observed among early life stage white sturgeon during acute and chronic exposures to copper. Sturgeon behavior was rapidly impaired and to the extent that survival in the field would be jeopardized, as fish would be swept downstream, or readily captured by predators. The objectives of this investigation were to illustrate protocols to quantify swimming activity during a series of acute copper exposures to determine time to effect during early lifestage development, and to understand the significance of these responses relative to survival of these vulnerable early lifestage fish. With mortality being on a time continuum, determining when copper first affects swimming ability helps us to understand the implications for population level effects. The techniques used are readily adaptable to experimental designs with other organisms and stressors.

Impaired regulation of divalent cations with acute copper exposure in the marine clam Mesodesma mactroides

The mechanism of copper (Cu) toxicity in marine invertebrates remains unclear. Therefore, marine clams (Mesodesma mactroides) were exposed (96h) to a concentration of dissolved Cu (1.6μmolL−1) inducing 10% mortality in sea water (30ppt). After in vivo exposure, tissue Cu accumulation (hemolymph, gill and digestive gland); hemolymph ionic (Na+, K+, Mg2+ and Ca2+) and osmotic concentrations; tissue (gill and digestive gland) ionic concentration, enzyme (Na+,K+-ATPase and carbonic anhydrase) activity, and oxygen consumption; and whole-body oxygen consumption were analyzed. Succinate dehydrogenase activity was evaluated in mitochondria isolated from gills and digestive gland and exposed (1h) in vitro to different concentrations of dissolved Cu (0.8, 7.7 and 78.7μmolL−1). In vivo exposure induced Cu accumulation in hemolymph, gills and digestive gland; increased Mg2+ and decreased Ca2+ concentration in hemolymph; decreased Mg2+ concentration, increased Na+,K+-ATPase activity and reduced carbonic anhydrase activity in gills; decreased Mg2+ concentration, increased Ca2+ concentration and increased Na+,K+-ATPase activity in digestive gland; and reduced gill, digestive gland and whole-body oxygen consumption. Succinate dehydrogenase activity was inhibited after in vitro exposure to 78.7μmolL−1 Cu. These findings indicate that Cu is an ionoregulatory toxicant in the marine clam M. mactroides. However, toxicity is related to disturbances in regulation of divalent cations (Mg2+ and Ca2+) without effect on regulation of major monovalent cations (Na+ and K+), as opposed to that observed in osmoregulating invertebrates exposed to Cu. However, other mechanism(s) of toxicity cannot be ruled out. Future studies must be performed to evaluate the consequence of the Cu-induced respiratory disturbances observed in M. mactroides.

The oxidative stress response in freshwater-acclimated killifish (Fundulus heteroclitus) to acute copper and hypoxia exposure

Aquatic organisms face multiple stressors in natural ecosystems. Here we examine the effects of moderate hypoxia and low-level copper (Cu) on freshwater (FW)-acclimated killifish. Both Cu and hypoxia can affect oxidative stress in fish, but it is unclear if in combination these two stressors would act synergistically. We exposed killifish for 96h to Cu in normoxia (total 23.4±0.9μg CuL−1), or either no Cu (2.33±0.01mg O2 L−1) or with Cu in hypoxia (23.6±0.8μg Cu L−1; 2.51±0.04mg O2 L−1), and compared them to normoxic controls with no added Cu (0.7±0.1μg Cu L−1; 9.10±0.00mg O2 L−1) at a hardness of 140mgL−1 as CaCO3 equivalents. Gills showed significant Cu accumulation with both excess waterborne Cu in normoxia and in hypoxia. This was accompanied by increases in gill catalase (CAT) activity but with no significant changes in either protein carbonyls or lipid peroxidation (TBARS). Hypoxia alone decreased gill protein carbonyls. Liver showed no change in Cu load, but a significant decline in CAT activity occurred with Cu in normoxia. Liver showed an increase in TBARS with Cu in normoxia. Cu when combined with hypoxia caused a significant decline in cytochrome c oxidase (COX) and citrate synthase (CS) activity in gill and liver. Thus, low waterborne levels of Cu and moderate hypoxia both affected gill and liver phenotypes. However, killifish are tolerant of Cu and hypoxia, and there was no evidence of a synergistic response to exposure to the two stressors combined compared to each stressor alone.

Acute Copper Toxicity and Acclimation to Copper Using the Behavioral Endpoint of Shoaling, in the Least Killifish (Heterandria formosa)

While copper is known to be neurotoxic, effects on behavior and especially on group behavior have received much less attention. Yet such behavioral effects can have important ecological consequences. This study determined whether shoaling behavior could be used as an indicator of acute copper toxicity and as an endpoint in studying acclimation in the least killifish (Heterandria formosa). For acute toxicity, least killifish were exposed to 0, 25, 50, or 100 μg/L of Cu for a 2-h duration and then tested for changes in shoaling behavior. The occurrence of copper acclimation was tested by pre-exposing fish to either 0 or 15 μg/L of Cu for a 7-day duration, then exposing them to 25, 50, or 100 μg/L of Cu to assess whether the two pre-exposure groups differed in their behavioral responses to high Cu levels. Behavioral responses were tested in a subdivided aquarium, with one side containing a group of conspecific fish and the other side the focal fish whose behavior was recorded for 3 min. Shoaling was based on the proximity of the focal fish to the divider separating it from the group of conspecific fish. Acute copper exposure resulted in significant decreases in both the time to first shoaling and in the total amount of time spent shoaling. Experiments assessing the occurrence of copper acclimation using shoaling as the toxicity endpoint did not detect a difference between the pre-exposure groups. Overall, this study demonstrated that acute copper exposure can alter shoaling behavior. However, least killifish shoaling behavior appears to be relatively insensitive as an endpoint to assess copper acclimation.

Alterations in Growth Related Genes (GH-I, IGF-I and IGF-II) Expression with Acute Copper Exposure in Rainbow Trout

Alterations in Growth Related Genes (GH-I, IGF-I and IGF-II) Expression with Acute Copper Exposure in Rainbow Trout

Acute responses of brown mussel ( Perna perna) exposed to sub-lethal copper levels: Integration of physiological and cellular responses

This study examined the effect of sub-lethal copper levels on selected physiological and cellular responses of the marine bivalve Perna perna. Animals were exposed to five environmentally relevant concentrations of 12.5, 25.0, 37.5 and 50.0 μg L −1 copper and metal accumulation was found to be significantly increased at the two higher copper concentrations after 24 h of exposure. Physiological responses found to increase during acute copper exposure included mucus secretion rate (at 25 and 50 μg L −1 copper), nitrogen excretion rates and oxygen consumption rates (both at 25 and 50 μg L −1 copper). Perna perna changed its substrate utilisation at 25, 37.5 and 50 μg L −1 copper in favour of protein-based metabolism. A higher degree of ROS induced DNA damage was observed at acute exposure to 37.5 and 50 μg L −1 copper. Filtration rate was unchanged during acute copper exposure. A model is proposed that integrates cellular and physiological responses to copper during short-term acute and long-term chronic exposures.

Effect of Acute Copper Sulfate Exposure on Olfactory Responses to Amino Acids and Pheromones in Goldfish (Carassius auratus)

Exposure of olfactory epithelium to environmentally relevant concentrations of copper disrupts olfaction in fish. To examine the dynamics of recovery at both functional and morphological levels after acute copper exposure, unilateral exposure of goldfish olfactory epithelia to 100 microM CuSO(4) (10 min) was followed by electro-olfactogram (EOG) recording and scanning electron microscopy. Sensitivity to amino acids (l-arginine and l-serine), generally considered food-related odorants, recovered most rapidly (three days), followed by that to catecholamines (3-O-methoxytyramine), bile acids (taurolithocholic acid) and the steroid pheromone, 17,20beta-dihydroxy-4-pregnen-3-one 20-sulfate, which took 28 days to reach full recovery. Sensitivity to the postovulatory pheromone prostaglandin F(2alpha) had not fully recovered even at 28 days. These changes in sensitivity were correlated with changes in the recovery of ciliated and microvillous receptor cell types. Microvillous cells appeared largely unaffected by CuSO(4) treatment. Cilia in ciliated receptor neurones, however, appeared damaged one day post-treatment and were virtually absent after three days but had begun to recover after 14 days. Together, these results support the hypothesis that microvillous receptor neurones detect amino acids whereas ciliated receptor neurones were not functional and are responsible for detection of social stimuli (bile acids and pheromones). Furthermore, differences in sensitivity to copper may be due to different transduction pathways in the different cell types.