Transfer and effects of cadmium in an experimental food chain involving the snail Helix aspersa and the predatory carabid beetle Chrysocarabus splendens

The transfer and the toxic effects of Cd were studied in an experimental food chain involving the snail Helix aspersa as prey organism and one of its natural predators, the carabid beetle Chrysocarabus splendens. Juvenile snails were fed plant-based food enriched with 0, 10, 50 and 100 microg g(-1) of Cd, then were offered as prey to beetle larvae from egg hatching to pupation stage. Cd concentrations in snail tissues increased with increasing Cd concentration in food and with duration of exposure. Bioaccumulation factors ranged from 1.87 to 3.39, showing that H. aspersa snails, even in their early life stages, belong to macroconcentrator species for Cd. No significant reduction of snail consumption by beetles was found in exposed groups. Cd concentrations in beetle larvae remained very low (lower than 1 microg g(-1) for all groups), demonstrating a very effective regulation capacity in beetle larvae. However, Cd concentrations in highest exposed groups were higher than those found in control groups. Cd contents in adult beetles were lower than in larvae, showing a loss of Cd during metamorphosis. Despite the low Cd concentrations found in beetles, their exposure to Cd contaminated snails led to 31% of mortality, which occurred only during pupation and for the highest exposure level. No clear sublethal effects were found. These results showed that snails inhabiting heavily polluted areas may represent a risk of secondary poisoning for predatory invertebrates and provided quantitative data on the transfer of Cd between two compartments of a terrestrial food chain.     

Anomalies on capture nets of Hydropsyche slossonae larvae (Trichoptera; Hydropsychidae) following a sublethal chronic exposure to cadmium

A laboratory study on the sublethal effects of cadmium (Cd) on the net-spinning process of the larvae of Hydropsyche slossonae was conducted in order to assess the potential of net anomalies as an indicator of chronic exposure to Cd. Two major anomalies with different frequency levels were identified after chronic exposure to 0.37, 1.2, 11.6, 21.4 and 43.3 microg l(-1) of Cd. The first was a distortion of the midline meshes where the diamond-shape structure is disrupted and the meshes are separated by extra strands (called 'midline' anomaly). The second aberration consisted of a distortion of the rectilinear structure of net opening by strands being fused or added over the meshes (called 'crossover' anomaly). The midline distortion may be linked to a physiological stress caused by Cd, which can affect the control of the net-spinning process. It was not possible to relate the crossover aberrations to a specific toxic action of Cd, but data indicated that both anomalies are independent from each other and that two modes of action could be implicated. Protein analyses of capture nets have revealed silk polypeptide modifications at the highest Cd concentration tested, indicating a possible effect of Cd interaction with silk proteins. However, neither a gradient-concentration nor a time-dependent response could be established with both aberration frequencies. Silk protein modifications would rather play a secondary role in the appearance of both net anomalies, and mostly at a high concentration level. Finally, the toxicity curves (EC(50)) show that the sensitivity threshold for both types of aberration ranged from 1 to 5 microg l(-1) which is highly sensitive compared with other sublethal effects of Cd on other macroinvertebrate species. Hence, the use of capture-net anomalies of hydropsychid larvae would represent a valuable indicator of sublethal toxicity induced by Cd and possibly by other metals in running waters.     

Short-term physiological responses to a severe acid stress in three macroinvertebrate species: a comparative study

The present study focuses on the sensitivity among freshwater invertebrate species to acidic stress. Three common macroinvertebrate species in the Vosges Mountains (North-Eastern France), Gammarus fossarum (Amphipoda), Hydropsyche pellucidula (Trichoptera) and Dinocras cephalotes (Plecoptera) were exposed for 24, 72 and 120 h to natural acidified water (pH=4.73+/-0.08, [Ca2+]=39.1+/-0.6 micromol l(-1), [Al(tot)]=28.4+/-1 micromol l(-1)). Short-term exposure to acid stress caused significant decreases both in survival rate and haemolymph ions ([Cl-] and [Na+]). The relative sensitivity to a natural acidic stress slightly differed among the species and was in the following order: G. fossarum, as the most sensitive, then H. pellucidula and D. cephalotes. Results of this study confirm the interest of in situ tests to assess the toxicity of short-term acid exposure. Finally, our results reinforce the hypothesis that transient acidification can offset the recovery of sensitive species of macroinvertebrates in streams chemically recovering from acidification either through liming or declining deposition.     

The interference of 2-chloro-5-oxo-3-hexene diacyl chloride (COHC) in the detection of strong mutagen MX

Laboratory experiments were conducted to examine the impact of cadmium (Cd) on survival of Diplostomum sp. cercariae. Freshly emerged cercariae were exposed to Cd solutions at concentrations ranging between 0.2 and 200 microg/l. The mortality patterns and mean survival times (MSTs) of the exposed parasites were determined by the Kaplan-Meier estimator and were compared (Log-Rank test) to corresponding patterns and estimators of the unexposed controls. Cd concentrations >20 microg/l caused statistically significant changes in the mortality pattern of Diplostomum sp. cercariae and reduced MST by at least five hours compared to the control group, where MST was 52 h. The results show that longevity of the free-living Diplostomum sp. cercariae can be reduced by direct exposure to heavy metals. Cd contamination of aquatic habitats thus potentially can have an impact on parasite populations and communities.     

Effects of cadmium on glutathione synthesis in hepatopancreas of freshwater crab, Sinopotamon yangtsekiense

Cadmium (Cd) is one of the most deleterious heavy metals in aquatic systems that could promote oxidative damage. To explore the effects of Cd exposure of a freshwater crab (Sinopotamon yangtsekiense) on hepatopancreatic glutathione (GSH) synthesis, crabs were exposed to the reagent with a dose range of 7.25-116.00 mg L(-1) for 48 h. The concentrations of GSH, oxidized glutathione (GSSG), NADPH and NADP(+), as well as the activities of enzymes involved in GSH synthesis, i.e. glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD), gamma-glutamylcysteine synthetase (gamma-GCS) were determined. Progressive depletion of cellular GSH content was observed with the increasing of Cd concentrations, while the level of GSSG remained constant. In response to Cd exposure, crabs showed significant induction of G6PD and NADPH, however, only up to moderate exposures. GR activity remained at a steady level at all exposure concentrations. The activity of gamma-GCS was significantly positively correlated with the Cd concentration. These results suggested that GSH synthesis could be activated against reactive oxygen species induced by lower Cd exposure; under the higher Cd exposure conditions, an inhibition of NADPH-dependant redox cycling and de novo GSH synthesis led to significant decrease in GSH content.     

Lethal effects on different marine organisms, associated with sediment�Cseawater acidification deriving from CO2 leakage

CO(2) leakages during carbon capture and storage in sub-seabed geological structures could produce potential impacts on the marine environment. To study lethal effects on marine organisms attributable to CO(2) seawater acidification, a bubbling CO(2) system was designed enabling a battery of different tests to be conducted, under laboratory conditions, employing various pH treatments (8.0, 7.5, 7.0, 6.5, 6.0, and 5.5). Assays were performed of three exposure routes (seawater, whole sediment, and sediment elutriate). Individuals of the clam (Ruditapes philippinarum) and early-life stages of the gilthead seabream, Sparus aurata, were exposed for 10?days and 72?h, respectively, to acidified clean seawater. S. aurata larvae were also exposed to acidified elutriate samples, and polychaete organisms of the specie Hediste diversicolor and clams R. philippinarum were also exposed for 10?days to estuarine whole sediment. In the fish larvae elutriate test, 100?% mortality was recorded at pH?6.0, after 48?h of exposure. Similar results were obtained in the clam sediment exposure test. In the other organisms, significant mortality (p?相似文献   

Metal bioaccumulation and metallothionein concentrations in larvae of Crassostrea gigas

Larval stages of bivalve molluscs are highly sensitive to pollutants. Oysters from a hatchery from Normandy (English Channel) were induced to spawn, and fertilized eggs were exposed to copper or cadmium for 24 h. Metal accumulation (from 0.125 to 5 microg Cu L(-1) and from 25 to 200 microg Cd L(-1)) and MT concentrations were measured in larvae. Compared to controls, larvae accumulated copper and cadmium with an increase in MT concentrations particularly with cadmium (i.e. 130.96 ng Cu (mg protein)(-1) and 12.69 microg MT (mg protein)(-1) at 1 microg Cu L(-1) versus 23.19 ng Cu (mg protein)(-1) and 8.92 microg MT (mg protein)(-1) in control larvae; 334.3 ng Cd (mg protein)(-1) and 11.70 microg MT (mg protein)(-1) at 200 microg Cd L(-1) versus 0.87 ng Cd (mg protein)(-1) and 4.60 microg MT (mg protein)(-1) in control larvae). Larvae were also obtained from oysters of a clean area (Arcachon Bay) and a polluted zone (Bidassoa estuary) and exposed to copper in the laboratory, their MT concentration was measured as well as biomarkers of oxidative stress. Biomarker responses and sensitivity to copper for the larvae from Arcachon oysters were higher than for those from Bidassoa.     

Chronic effects of Cd on reproduction of Polypedilum nubifer (Chironomidae) through water and food

Chronic effects of Cd on reproduction of Polypedilum nubifer (Chironomidae) were investigated by Cd-exposure from the egg stage using a flow-through aquarium. No significant effect of Cd on reproduction was observed in the midge larvae which had been exposed to 10 or 20 microg Cd litre(-1). Emergence of the Cd-exposed larvae peaked several days before that of the control, although growth was impaired in 1st and/or 2nd instars. The percentage emergence success decreased to about 46% of the control at 40 microg Cd litre(-1). However, other reproductive processes (adult sex ratio, oviposition success and egg hatchability) were not impaired. The emergence success decreased to less than 3% of the control at 80 microg Cd litre(-1). The emergence success of midge larvae which had been fed Cd-contaminated food with 220 or 1800 microg Cd g(-1) decreased to nearly 60% of the control. However, other reproductive processes were not impaired. Emergence success of larvae exposed to food containing 22 microg Cd g(-1) was unaffected.     

Metal accumulation in the polychaete Hediste japonica with emphasis on interaction between heavy metals and petroleum hydrocarbons

The accumulation of cadmium (Cd) and copper (Cu) in the polychaete Hediste japonica exposed to the mixture of Cd (or Cu) and petroleum hydrocarbons (PHCs) was investigated and compared with that exposed to single Cd (or Cu). The increased bioavailability of Cd or Cu with exposure concentrations resulted in an increase in the accumulation and net accumulation rate of Cd or Cu during single metal exposure. The net accumulation rate of Cd increased, but the net accumulation rate of Cu decreased with exposure time during single metal exposure, suggesting that H. japonica could actively regulate Cu burden in their body by inhibition of absolute uptake or promotion of excretion. The interactions between Cd (or Cu) and PHCs had complicated influences on the net accumulation rate of Cd and Cu in H. japonica under the condition of the binary mixture, which are dependent on their concentration combinations and exposure time.     

Effects of episodic sedimentation on the net-spinning caddisflies Hydropsyche betteni and Ceratopsyche sparna (Trichoptera: Hydropsychidae)

Net-spinning caddisflies commonly inhabit the chronically sedimented waters of midwestern agricultural catchments despite the presumed costs of sedimentation-induced gill-and net-fouling. We conducted a laboratory experiment to determine whether larval growth and survival of Hydropsyche betteni and Ceratopsyche sparna are affected by daily exposure to moderate levels of sedimentation. Sedimentation did not alter the relative growth rate of either species although slight losses by H. betteni and gains by C. sparna produced significant differences between species. H. betteni had a decreased likelihood of survival in sedimentation treatments relative to controls, but significantly outperformed C. sparna overall. Larval C. sparna are reportedly more sensitive than H. betteni to the instream effects of agricultural land use; however, the results of this experiment suggest that this differential sensitivity is probably not caused by episodic increases in suspended sediment concentration.     

Proteomic analysis in the lichen Physcia adscendens exposed to cadmium stress

This work was undertaken to explore the potential of proteomics to dissect parallel and consecutive events of cadmium stress response in the lichen Physcia adscendens (Fr.) H. Olivier. Thalli were exposed to 0 (control) and 36 μM Cd for 6, 18, 24 and 48 h. Two-dimensional electrophoresis and mass spectrometry analyses showed an 80-85% spot identity between 6 and 18 h vs. 24 and 48 h of Cd exposure. Putative heat-shock proteins and glutathione S-transferase generally increased their expression all over the Cd treatments. By contrast, ABC transporters were underexpressed after 6-18 h, but in some cases induced after 24-48 h of Cd exposure. The cytochrome P450 appeared to have a variable expression pattern over time. Overall these data suggest that a considerable importance in the response of P. adscendens thalli to Cd stress can be assumed by differential expression of various protein families.     

Different compensatory mechanisms in two metal-accumulating aquatic macrophytes exposed to acute cadmium stress in outdoor artificial lakes

Mechanisms underlying cadmium (Cd) detoxification were compared in two aquatic macrophytes commonly used in phytoremediation, namely Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms. To simulate Cd pollution in the open environment, plants growing in outdoor artificial lakes were exposed for 21d to either 25 or 100microM Cd, in two consecutive years. Toxicity symptoms were absent or mild in both species. Metal accumulation was much higher in the roots of P. stratiotes, whereas in E. crassipes a comparatively higher fraction was translocated to the leaves. In both species, Cd was neither included in phenolic polymers or Ca-oxalate crystals, nor altered the levels of Cd-complexing organic acids. Glutathione levels were constitutively remarkably higher and much more responsive to Cd exposure in P. stratiotes than in E. crassipes. Abundant phytochelatin synthesis occurred only in P. stratiotes, both in roots and in leaves. In E. crassipes, on the other side, the constitutive levels of some antioxidant enzymes and ascorbate were higher and more responsive to Cd than in P. stratiotes. Thus, in these two aquatic plants grown in the open, different detoxification mechanisms might come into play to counterbalance Cd acute stress.     

Comparison of two wild rodent species as sentinels of environmental contamination by mine tailings

Background

Contamination with heavy metals is among the most hazardous environmental concerns caused by mining activity. A valuable tool for monitoring these effects is the use of sentinel organisms. Particularly, small mammals living inside mine tailings are an excellent study system because their analysis represents a realistic approach of mixtures and concentrations of metal exposure.

Purpose

We analyzed metal tissue concentrations and DNA damage levels for comparison between genders of a sentinel (Peromyscus melanophrys) and a nonsentinel (Baiomys musculus) species. Also, the relationship between DNA damage and the distance from the contamination source was evaluated.

Methods

This study was conducted in an abandoned mine tailing at Morelos, Mexico. Thirty-six individuals from both species at the exposed and reference sites were sampled. Metal concentrations in bone and liver of both species were analyzed by atomic absorption spectrophotometry, and DNA damage levels were assayed using the alkaline comet assay.

Results

In general, concentrations of zinc, nickel, iron, and manganese were statistically higher in exposed individuals. A significant effect of the organ and the site on all metal tissue concentrations was detected. Significant DNA damage levels were registered in the exposed group, being higher in B. musculus. Females registered higher DNA damage levels than males. A negative relationship between distance from the mine tailing and DNA damage in B. musculus was observed.

Conclusions

We consider that B. musculus is a suitable species to assess environmental quality, especially for bioaccumulable pollutants??such as metals??and recommend that it may be considered as a sentinel species.     

First and second line mechanisms of cadmium detoxification in the lichen photobiont Trebouxia impressa (Chlorophyta)

“First line” defence mechanisms, such as phytochelatin biosynthesis, and “second line” mechanisms, such as stress protein induction, were investigated in cadmium-exposed cells of Trebouxia impressa Ahmadjian, a green microalgal species that is a common photobiont of the lichen Physcia adscendens (Fr.) H. Olivier. When T. impressa cells were exposed to 0, 9 and 18 μM Cd for 6, 18 and 48 h, glutathione and phytochelatins efficiently protected the cells against Cd damage. By contrast, the highest Cd concentration (36 μM) at the longest exposure-time (48 h) caused marked drops in glutathione and phytochelatin content, several types of ultrastructural damage, and decreases in cell density and total chlorophyll concentration. In this case, induction of stress proteins was observed, but only long after the induction of phytochelatins. Thus, stress proteins could represent a “second line” mechanism to counteract Cd stress, activated when there is a decline in the “first line” mechanism of Cd detoxification given by phytochelatins.     

Reproductive impairment of sea urchins upon chronic exposure to cadmium. Part I: Effects on gamete quality

Successful reproduction is a determining factor for species survival. Pollution may impair reproductive success of adults through effects on gamete quality. Reproductive impairment of the sea urchin Anthocidaris crassispina upon chronic (4 weeks) exposure to 0.01 and 0.1 mg l-1 Cd2+ was investigated. Criteria used for assessing gamete quality included sperm motility, egg morphology, fertilization rate and dynamics of first cleavage. A dose-response relationship was found between Cd2+ levels and changes in sperm motility, and percentage fertilization. Sperm motility, measured by computer-assisted sperm analysis, indicated that percent motile sperm, velocities, and percent sperm with normal trajectory were significantly affected by chronic exposure to > or = 0.1 mg l-1 Cd2+. A decline in sperm motility was also accompanied by a decrease in fertilization success of sea urchin sperm. Width/height ratio of sea urchin eggs was not affected by cadmium, but larger egg sizes were found when sea urchins were exposed to 0.1 mg l-1 Cd2+. Male sea urchins exposed to Cd2+ produced poorer quality sperm, as indicated by a lower percent fertilization and lower cleavage rate, implying that male sea urchins were more sensitive than females to chronic Cd2+ exposure. Results of the present study provide an explanation of reproductive impairment in marine invertebrates upon chronic exposure to Cd2+.     

Assimilation efficiencies of Cd and Zn in the common carp (Cyprinus carpio): effects of metal concentration, temperature and prey type

The impact of several factors on the assimilation efficiency (AE) of Cd and Zn from food in the common carp (Cyprinus carpio) was studied. Tested prey species were midge larvae (Chironomus riparius), zebra mussels (Dreissena polymorpha) and oligochaetes (Tubifex tubifex). The Cd load of the larvae did not affect the Cd AE in the carp. The Zn AE however, was negatively related to the Zn load of the prey. Food quantity and starvation of the carp did not significantly affect the Cd AE. For Zn, a significant decrease in AE was found when carp were fed ad libitum. Decreasing the temperature from 25 degrees C to 15 degrees C did not influence the Cd AE, while for Zn a significant decrease of the AE was measured. Carp assimilated Cd from both zebra mussels and oligochaetes with a significantly lower efficiency in comparison to the midge larvae, although Zn AEs was prey independent.     

Cadmium effect on the ovarian structure in earthworm Dendrobaena veneta (Rosa)

Cadmium effects on the ovary structure and oocytes were tested in earthworms Dendrobaena veneta exposed to 10 and 50 mg Cd kg(-1) in soil after 10 and 20 days of the experiment. In both experimental doses cadmium caused damage to the structure of the ovary but the effects were different in each group. At 10 mg Cd kg(-1) concentration in soil, young stages of oocytes and trophocytes were most sensitive to cadmium deleterious effects whereas somatic cells in the ovarian stroma were only slightly affected. Cadmium. at a concentration of 50 mg Cd kg(-1) in soil caused most damage in the somatic cells leading to the occurrence of unnaturally swollen elements and desmosomes destruction. At both experimental concentrations cadmium induced degenerative changes in cell nuclei and an increase in number of cell organelles (RER and Golgi complex elements) in the cytoplasm of oocytes and trophocytes. These also proved to be more active. No ultrastructural changes were manifested in oogonia. In both experimental groups degenerative changes occurred as early as after 10 days of Cd exposure.     

Cadmium accumulation and its influence on lipid peroxidation and antioxidative system in an aquatic plant, Bacopa monnieri L

Bacopa monnieri L. plants exposed to 10, 50, 100 and 200 microM cadmium (Cd) for 48, 96 and 144 h were analysed with reference to the accumulation of metal and its influence on various enzymatic and non-enzymatic antioxidants, thiobarbituric acid reactive substances (TBARS), photosynthetic pigments and protein content. The accumulation of Cd was found to be increased in a concentration and duration dependent manner with more Cd being accumulated in the root. TBARS content of the treated roots and leaves increased with increase in Cd concentration and exposure periods, indicating the occurrence of oxidative stress. Induction in the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and guiacol peroxidase (GPX) was recorded in metal treated roots and leaves of B. monnieri. In contrast, a significant reduction in catalase activity in Cd treated B. monnieri was observed. An increase was also noted in the levels of cysteine and non-protein thiol contents of the roots of B. monnieri followed by a decline. However, in leaves, cysteine and non-protein thiol contents were found to be enhanced at all the Cd concentrations and exposure periods. A significant reduction in the level of ascorbic acid was observed in a concentration and duration dependent manner. The total chlorophyll and protein content of B. monnieri decreased with increase in Cd concentration at all the exposure periods. Results suggest that toxic concentrations of Cd caused oxidative damage as evidenced by increased lipid peroxidation and decreased chlorophyll and protein contents. However, B. monnieri is able to combat metal induced oxidative injury involving a mechanism of activation of various enzymatic and non-enzymatic antioxidants.     

Formetanate toxicity and changes in antioxidant enzyme system of <Emphasis Type="Italic">Apis mellifera</Emphasis> larvae

Substantial percentage of world food production depends on pollinating service of honeybees that directly depends on their health status. Among other factors, the success of bee colonies depends on health of developed larvae. The crucial phase of larval development is the first 6 days after hatching when a worker larva grows exponentially and larvae are potentially exposed to xenobiotics via diet. In the present study, we determined the lethal concentration LC₅₀ (72 h) following single dietary exposure of honeybee larvae to formetanate under laboratory conditions, being also the first report available in scientific literature. Activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) were also measured in the homogenates of in vitro reared honeybee larvae after single formetanate exposure. Decreased specific activity of SOD and increased activities of CAT and GST suggest the induction of oxidative stress. Higher levels of thiobarbituric reactive species in all samples supported this fact. Comparing determined larval toxicity (LC₅₀ of 206.01 mg a.i./kg diet) with adult toxicity data, we can suppose that the larvae may be less sensitive to formetanate than the adult bees.