Cytotoxic and morphological effects of microcystin‐LR,cylindrospermopsin, and their combinations on the human hepatic cell line HepG2

Cylindrospermopsin (CYN) and Microcystin‐LR (MC‐LR) are toxins produced by different cyanobacterial species, which are found mainly in freshwater reservoirs. Both of them can induce, separately, toxic effects in humans and wildlife. However, little is known about the toxic effects of the combined exposure, which could likely happen, taking into account the concomitant occurrence of the producers. As both cyanotoxins are well known to induce hepatic damage, the human hepatocellular HepG2 cell line was selected for the present study. Thus, the cytotoxicity of both pure cyanotoxins alone (0–5 μg/mL CYN and 0–120 μg/mL MC‐LR) and in combination for 24 and 48 h was assayed, as long as the cytotoxicity of extracts from CYN‐producing and nonproducing cyanobacterial species. The potential interaction of the combination was evaluated by the isobologram or Chou–Talalay's method, which provides a combination index as a quantitative measure of the two cyanotoxins interaction's degree. Moreover, a morphological study of the individual pure toxins and their combinations was also performed. Results showed that CYN was the most toxic pure cyanotoxin, being the mean effective concentrations obtained ≈4 and 90 μg/mL for CYN and MC‐LR, respectively after 24 h. However, the simultaneous exposure showed an antagonistic effect. Morphologically, autophagy, at low concentrations, and apoptosis, at high concentrations were observed, with affectation of the rough endoplasmic reticulum and mitochondria. These effects were more pronounced with the combination. Therefore, it is important to assess the toxicological profile of cyanotoxins combinations in order to perform more realistic risk evaluations.     

Effects of the fungicide pyrimethanil on biofilm and organic matter processing in outdoor lentic mesocosms

The effect of the fungicide pyrimethanil (0.7 mg L^?1) on biofilm development and alder leaf litter decomposition in aquatic ecosystems was assessed in outdoor lentic mesocosms immediately and 274 days after pyrimethanil application. Pyrimethanil decreased ergosterol concentrations (an indicator of fungal biomass) and the abundance and richness of the macroinvertebrate community associated with decomposing leaves. However, because neither fungi nor macroinvertebrates were main factors contributing to decomposition in this particular system, organic matter processing rates were not affected. After 274 days, pyrimethanil concentration in the water column was ≤0.004 mg L^?1 but richness, biomass and composition of the invertebrate community associated with decomposing leaf-litter still showed the effect. The comparison of ergosterol (a molecule existing on both algae and fungal cell membranes), with chlorophyll (an indicator of algal biomass) associated with biofilm suggests that pyrimethanil may decrease fungal biomass and alter the relative abundance of algae and fungi on biofilm developing in control- and treated-mesocosms.     

Ecotoxicity studies of the levulinate ester series

The increasing interest in the development of novel green solvents has led to the synthesis of benign alternative products with minimized environmental impacts. However, most of published studies on green solvents focus primarily on their physicochemical properties, with limited emphasis on absence of ecotoxicological assessment. In this study, we evaluated the acute ecotoxicity of four levulinates (levulinic acid, methyl levulinate, ethyl levulinate and butyl levulinate) on freshwater algae (Chlamydomonas reinhardtii), bacteria (Vibrio fischeri), daphnids (Daphnia magna) and earthworms (Eisenia foetida) using various dose–response tests. As a general trend, the toxicity of levulinate esters in aquatic exposure (assessed as the EC₅₀) increased as a function of increasing alkyl chain length; accordingly, the most toxic compound for the aquatic organisms was butyl levulinate, followed by ethyl levulinate and methyl levulinate. The most toxic compound for E. foetida (terrestrial exposure) was methyl levulinate, followed by ethyl levulinate, butyl levulinate and levulinic acid; in this case, we observed an inverse relationship between toxicity and alkyl chain length. Based on both the lowest EC₅₀ found in the aquatic media and the ratio between predicted environmental concentration and the predicted no-effect concentration, we have estimated the maximum allowable values in the environment for these chemicals to be 1.093 mg L^?1 for levulinic acid, 2.761 mg L^?1 for methyl levulinate, 0.982 mg L^?1 for ethyl levulinate and 0.151 mg L^?1 for butyl levulinate.     

Photosynthetic sensitivity of phytoplankton to commonly used pharmaceuticals and its dependence on cellular phosphorus status

Recently pharmaceuticals have become significant environmental pollutants in aquatic ecosystems, that could affect primary producers such as microalgae. Here we analyzed the effect of pharmaceuticals on the photosynthesis of microalgae commonly found in freshwater—two species of Chlorophyceae and a member of the Eustigmatophyceae, via PAM fluorometry. As pharmaceuticals, three medicines often consumed in households were chosen: (i) fluoxetine, an antidepressant, (ii) propranolol, a β-blocker and (iii) ibuprofen, an anti-inflammatory and analgesic medicine. The EC₅₀ for the quantum yield of photosystem II in phytoplankton acclimated to inorganic phosphorus (P_i)-replete and P_i-limited conditions was estimated. Acute toxicity experiments over a 5 h exposure revealed that Nannochloropsis limnetica was the least sensitive to pharmaceuticals in its photosynthetic yield out of all species tested. Although the estimation of sub-lethal effects can be vital in contrast to that of LC₅₀s, the EC₅₀ values in all species and for all medicines were orders of magnitude higher than concentrations found in polluted surface water. Chlamydomonas reinhardtii was the most sensitive to fluoxetine (EC₅₀ of 1.6 mg L^?1), and propranolol (EC₅₀ of 3 mg L^?1). Acutodesmus obliquus was most sensitive to ibuprofen (EC₅₀ of 288 mg L^?1). Additionally, the sensitivity to the pharmaceuticals changed under a P_i-limitation; the green algae became less sensitive to fluoxetine and propranolol. In contrast, P_i-limited algal species were more sensitive to ibuprofen. Our results suggest that the sensitivity of algae to pharmaceuticals is (i) highly compound- and species-specific and (ii) dependent on the cellular P status.     

Presence and bioaccumulation of microcystins and cylindrospermopsin in food and the effectiveness of some cooking techniques at decreasing their concentrations: A review

Microcystins (MCs) and cylindrospermopsin (CYN) are among the cyanotoxins which occur naturally, produced by different cyanobacteria species when they grow or proliferate under favorable environmental conditions. From a toxicological point of view, their relevance is due to the deleterious effects that they have been reported to induce in a wide range of organisms, including humans. Cyanotoxins intake from contaminated water and food is an important source of human exposure. Various edible aquatic organisms, plants, and food supplements based on algae, can bioaccumulate these toxins. A thorough review of the scientific data available on this topic is provided, the studies on MCs being much more numerous than those focused on CYN. The scientific literature suggests that these cyanotoxins can be accumulated at concentrations higher than their respective recommended tolerable daily intake (TDI). Finally, the influence of different cooking procedures on their levels in food has been considered. In this regard, again studies on the matter dealing with CYN have been not yet raised. MCs contents have been reported to be reduced in muscle of fish after boiling, or cooking in a microwave-oven, although the effect of other traditional cooking processes such as frying, roasting or grilling have not been demonstrated.     

Canadian water quality guidelines for chromium

Canadian Water Quality Guidelines (CWQG) are numerical or narrative limits that protect designated water uses. Development of CWQG is based on review of chromium's properties, uses, fate in the environment, ambient levels, accumulation in biota, and toxicity. Chromium's principal uses and entry into the environment include electroplating, production of paints and pigments, tanning, wood preservation, chromium chemicals production, metal smelting, and pulp and paper production. Concentrations of chromium in Canada range between 1 and 545,000 ng·m⁻³ in air, 0.001 and 0.165 mg·L⁻¹ in water, nondetectable and 31,000 mg·kg⁻¹ in sediments, 10 and 5000 mg·kg⁻¹ in soils, 0.006 and 18 mg·kg⁻¹ in plants, and 0.03 and 1.6 mg·kg⁻¹ in animals. In nature, trivalent chromium sorbs to various ligands and forms insoluble entities becoming unavailable for uptake by biota. Hexavalent chromium forms many soluble salts that can enter body membranes and induce a toxic response. Estimates of toxicity of hexavalent chromium to aquatic life range from 0.0006 mg·L⁻¹ (reduction in algal growth) to 1000 mg·L⁻¹ (decrease in rest time of Chironomus tentans). For trivalent chromium the toxicity ranges from 0.002 mg·L⁻¹ (reduction in filtering rate of Perna perna) to 937 mg·L⁻¹ (48-h LC₅₀ of Asellus aquaticus). Plants are affected by the concentrations of hexavalent chromium ranging from 0.16 mg·L⁻¹ (growth reduction in lettuce) to 75 mg·L⁻¹ (no effects in sweet orange). For trivalent chromium the toxicity ranges between 0.104 mg·L⁻¹ (reduction in root growth of oats) and 50 mg·L⁻¹ (stunted growth of corn and tomato). Terrestrial animals such as the beagle dog can be affected by concentrations exceeding 62.7 mg·L⁻¹ (Cr VI). Mice can tolerate 100 mg·L⁻¹ of hexavalent chromium. Trivalent chromium has adverse effects on rats and mice at 28.0 mg·L⁻¹. For freshwater life, guidelines of 0.001 (Cr VI; full) and 0.008 (Cr III; interim) mg·L⁻¹ are recommended. For marine life, guidelines of 0.001 (Cr VI; draft) and 0.05 (Cr III; interim) mg·L⁻¹ are recommended. Irrigation guidelines are set at 0.008 (Cr VI) and 0.005 (Cr III). A guideline of 0.05 mg·L⁻¹ is recommended for drinking and livestock waters. © 1997 by John Wiley & Sons, Inc. Environ Toxicol Water Qual 12: 123–183, 1997     

Comparative bioaccumulation and effects of purified and cellular extract of cylindrospermopsin to freshwater fish Hoplias malabaricus

Many tropical freshwater ecosystems are impacted by cyanobacteria blooms increasing the risk of cyanotoxins exposure to aquatic organisms while human populations may be exposed by eating fish, drinking water, or dermal swimming. However, few toxicological data are available on the influence of cyanobacteria blooms in particular, cylindrospermopsin (CYN) on Brazilian neotropical fish. A number of studies demonstrated the ability of CYN to bioaccumulate in freshwater organisms and consequently enter the human food chain. The aim of the current study was to examine the effects of CYN following single intraperitoneal injection (50 µg/kg) of purified CYN (CYNp) or aqueous extract of CYN-producing cyanobacteria extract (CYNex) after 7 or 14 days. Biomarkers such as histopathology (liver), oxidative stress (liver and brain), and acetylcholinesterase (AChE) activity (muscle and brain) were utilized in order to assess the influence of CYN on Hoplias malabaricus. In terms of AChE activity, administration of CYNex and CYNp both muscle and brains were used as target tissues. In brain an increase of glutathione S-transferase (GST) activity and lipid peroxidation (LPO) levels was noted suggesting an imbalance in redox cycling. The majority of biomarkers did not present significant alterations in liver, but an elevation in superoxide dismutase (SOD) and glucose 6 phosphate dehydrogenase (G6PDH) activities was found. Different profiles of GST activity were observed in both studied groups (CYNex and CYNp) while LPO (CYNex and CYNp) and protein carbonylation (PCO) (CYNp) levels increased after exposure to CYN. The incidence of necrosis, melanomacrophages centers, and free melanomacrophages were detected as evidence of cell death and immune responses. Nonprotein thiols (NPT) levels were not markedly affected in both exposed groups. Data demonstrated that in vivo exposure to CYN produced biochemical and morphological disturbances in liver and brain of H. malabaricus.     

Toxicity of phthalate esters exposure to carp (Cyprinus carpio) and antioxidant response by biomarker

To study the toxic effects of phthalate esters on the aquatic creatures, carps were exposed to dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) of six different concentrations for 96 h-LC₅₀ measurements. It shows that the 96 h-LC₅₀ is 16.30 and 37.95 mg L^?1, thus the safe concentration (1/10LC₅₀) is 1.63 mg L^?1. The activities of xanthine oxidase (XOD) and catalase (CAT) were measured in liver to carp exposure for single or combinations of DBP and DEHP. The quantity of malonic dialdehyde (MDA) was also measured in the same way. XOD, CAT and MDA had shown an evident change while exposure time and concentration increased, combined exposure can aggravate this change. They might be used as early warning indicators and monitors, and have potentials in the ecological risk assessment.     

Oxidation of Cylindrospermopsin by Fenton Process: A Bench-Scale Study of the Effects of Dose and Ratio of H2O2 and Fe(II) and Kinetics

The cyanotoxin cylindrospermopsin (CYN) has become a significant environmental and human health concern due to its high toxicological potential and widespread distribution. High concentrations of cyanotoxins may be produced during cyanobacterial blooms. Special attention is required when these blooms occur in sources of water intended for human consumption since extracellular cyanotoxins are not effectively removed by conventional water treatments, leading to the need for advanced water treatment technologies such as the Fenton process to produce safe water. Thus, the present study aimed to investigate the application of the Fenton process for the degradation of CYN at bench-scale. The oxidation of CYN was evaluated by Fenton reaction at H₂O₂/Fe(II) molar ratio in a range of 0.4 to 4.0, with the highest degradation of about 81% at molar ratio of 0.4. Doubling the concentrations of reactants for the optimized H₂O₂/Fe(II) molar ratio, the CYN degradation efficiency reached 91%. Under the conditions studied, CYN degradation by the Fenton process followed a pseudo-first-order kinetic model with an apparent constant rate ranging from 0.813 × 10⁻³ to 1.879 × 10⁻³ s⁻¹.     

Congo red dye affects survival and reproduction in the cladoceran <Emphasis Type="Italic">Ceriodaphnia dubia</Emphasis>. Effects of direct and dietary exposure

Nearly 7?00000 tons of dyes are produced annually throughout the world. Azo dyes are widely used in the textile and paper industries due to their low cost and ease of application. Their extensive use results in large volumes of wastewater being discharged into aquatic ecosystems. Large volume discharges constitute a health risk since many of these dyes, such as Congo Red, are elaborated with benzidine, a known carcinogenic compound. Information regarding dye toxicity in aquatic ecosystems is limited. Therefore, the aim of the present study was to evaluate the effect of Congo Red on survival and reproduction of Ceriodaphnia dubia. We determined the 48?h median lethal concentration (LC₅₀) and evaluated the effects of sublethal concentrations in subchronic exposures by using as food either fresh algae or algae previously exposed to the dye. LC₅₀ was 13.58?mg?L^?1. In subchronic assays, survival was reduced to 80 and 55?%, and fertility to 40 and 70?%, as compared to the control, in C. dubia fed with intoxicated cells or with the mix of intoxicated?+?fresh algae, respectively, so the quantity and type of food had a significant effect. We determined that Congo Red is highly toxic to C. dubia since it inhibits survival and fertility in concentrations exceeding 3?mg?L^?1. Our results show that this dye produces negative effects at very low concentrations. Furthermore, our findings warn of the risk associated with discharging dyes into aquatic environments. Lastly, the results emphasize the need to regulate the discharge of effluents containing azo dyes.     

Cadmium induced oxidative damage and apoptosis in the hepatopancreas of <Emphasis Type="Italic">Meretrix meretrix</Emphasis>

Even trace amounts of cadmium (Cd), a non-essential metal, are known to be toxic to aquatic organisms. Here we investigated the relationship between cadmium ion (Cd²⁺) exposure and oxidative damage and apoptosis in the hepatopancreas of the clam Meretrix meretrix. Clams were exposed to different concentrations of Cd²⁺ (0, 1.5, 3, 6 and 12 mg L^?1) for 5 days. We monitored both antioxidant enzyme activity, including that of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), and levels of malondialdehyde (MDA), glutathione (GSH) and glutathione disulfide (GSSG). Apoptosis of hepatopancreatic cells was detected by DNA laddering and AO/EB double fluorescent staining. The results show that the rate of apoptotis, MDA levels, and caspase-3 activity, increased with Cd²⁺ concentration, whereas GPx activity and the ratio of GSH/GSSG, decreased. SOD and CAT enzyme activity first increased, then decreased, with increasing Cd²⁺ concentration; peak activity of these enzymes was recorded in the 3 mg L^?1 Cd²⁺-treatment group. These results show that Cd-induced oxidative damage can both induce, and aggravate, apoptosis in the hepatopancreatic cells of clams, even at Cd²⁺ concentrations far below the semi-lethal dose for adult clams. The observed changes in caspase-3 activity enhanced significantly at lower Cd²⁺ concentrations, indicating that caspase-3 is a suitable biomarker for heavy metal pollution, especially cadmium pollution, in marine organisms.     

Chronic exposure of river sediments to environmentally relevant levels of tetracycline affects bacterial communities but not denitrification rates

The effects of tetracycline (TC) at chronic sub-inhibitory exposure concentrations on benthic denitrification rates and bacterial communities were explored. River sediments were continuously exposed to different TC concentrations (0.5, 20 and 10,000 μg L^?1) for 2 weeks in flow-through reactors allowing denitrification and bacterial growth conditions. Bacterial communities were fingerprinted by Denaturing Gradient Gel Electrophoresis of 16S rRNA gene amplification products. Cultivable denitrifiers enriched from the sediment were tested for TC resistance (2–128 mg L^?1). Denitrification rates were unaffected by exposure to TC, regardless of concentration. In contrast, the bacterial community composition changed significantly from sub-inhibitory (ng-μg L^?1) to therapeutic (mg L^?1) exposure concentrations. Furthermore the cultivable denitrifiers showed a high TC sensitivity (<4 mg L^?1). Maintenance of efficient benthic denitrification rates, even at the highest level of TC exposure most likely originated from an adaptation of the autochthonous bacterial community where dominant species become those that acquire, or already have resistance to antibiotics.     

Organophosphorous insecticides as herbicide synergists on the green algae <Emphasis Type="Italic">Pseudokirchneriella subcapitata</Emphasis> and the aquatic plant <Emphasis Type="Italic">Lemna minor</Emphasis>

Models proposed for risk assessment of chemical mixtures assume no interactions between the chemicals. There are, however, studies indicating that some organophosporous insecticides can inhibit the detoxification of other chemicals in plants thereby enhancing their effect. The present study investigates whether interactions between selected organophosporous insecticides and herbicides can take place in the aquatic algae Pseudokirchneriella subcapitata and the aquatic macrophyte Lemna minor. For both species binary mixtures of the organophosphate insecticides: malathion, endosulfan and chlorpyrifos were tested together with the herbicides metsulfuron-methyl, terbutylazine and bentazone. For mixtures with malathion on algae, dose-response surfaces were made and the results tested against the model of concentration addition (CA) and independent action (IA). The Lemna minor tests showed no indication of synergy for any of the combinations, on the contrary, significant antagonism was found for several of the mixtures. The response surface analysis showed antagonism in relation to both concentration addition and independent action for mixtures between malathion and metsulfuron-methyl and terbuthylazine, while the mixtures with bentazone could be explained with CA. The study shows no indications of synergistic interactions between the tested pesticides, confirming the applicability of CA as a reference model predicting mixture effects of pesticides for aquatic plants and algae.     

Individual and combined effects of cadmium and copper on the growth response of Chlorella vulgaris

The individual and combined effects of cadmium and copper on the growth response of the green alga, Chlorella vulgaris, were examined. The effects of pH alone, and in combination with copper were also evaluated. An increase in cadmium and copper concentrations caused a significant reduction in the growth of C. vulgaris cells, and the corresponding EC₅₀ values were 1.02 and 4.01 mg L⁻¹, respectively. For a pH range of 2–7, the inhibitory effect due to increased copper concentrations (coupled with the resulting drop in pH) was significantly higher than the impact due to increased acidity (by addition of HCl) alone. At lower metal concentrations (5 mg L⁻¹ Cu + < 2 mg L⁻¹ Cd or 2.5 mg L⁻¹ Cd + < 4 mg L⁻¹ Cu), a combination of copper and cadmium appeared to have a stronger inhibitory effect on cell growth than that of a single metal. In contrast, at higher metal concentrations (5 mg L⁻¹ Cu + > 2 mg L⁻¹ Cd or 2.5 mg L⁻¹ Cd + > 4 mg L⁻¹ Cu), the effect of a single metal exhibited a significantly stronger effect compared to a combination of the two metals. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 347–353, 1999     

Impact of multiple anthropogenic stressors on freshwater: how do glyphosate and the invasive mussel <Emphasis Type="Italic">Limnoperna fortunei</Emphasis> affect microbial communities and water quality?

The study of the joint effect of multiple anthropogenic stressors is important because the emerging consequences are often unpredictable on the basis of knowledge of single effects. We explored the joint impact of glyphosate and the invasive golden mussel Limnoperna fortunei on freshwater phytoplankton, bacterioplankton and periphyton, and on the physical and chemical properties of the water. We manipulated both stressors simultaneously in a 25-day experiment using outdoor mesocosms; we assayed technical-grade glyphosate acid at four concentrations: 0, 1, 3 and 6 mg gly L^?1 under scenarios with and without mussels. The addition of the glyphosate significantly increased total phosphorus according to the concentration used; the high clearance rate of L. fortunei significantly decreased phytoplanktonic abundance leading to low values of turbidity. The mussel significantly stimulated the development of filamentous green algae (metaphyton). Interestingly, the combined effect revealed that L. fortunei accelerated the dissipation of glyphosate, which showed a 4-fold decrease in its half-life; this promoted the rapid bioavailability of glyphosate-derived phosphorus in the water. The interaction had a synergistic effect on soluble reactive phosphorus concentrations and was directly dependent on the concentration of glyphosate. A synergistic effect was also observed on bacterioplankton, water turbidity and metaphyton, thus inducing enhanced and rapid eutrophication. The ability of mussels to reduce glyphosate in water may be valued as positive, but our results allow us to predict that the invasion of Limnoperna fortunei in natural freshwater systems contaminated by glyphosate will accelerate the negative impact of the herbicide associated with eutrophication.     

New evidences of Roundup® (glyphosate formulation) impact on the periphyton community and the water quality of freshwater ecosystems

Argentina is the second largest world producer of soybeans (after the USA) and along with the increase in planted surface and production in the country, glyphosate consumption has grown in the same way. We investigated the effects of Roundup^® (glyphosate formulation) on the periphyton colonization. The experiment was carried out over 42 days in ten outdoor mesocosms of different typology: “clear” waters with aquatic macrophytes and/or metaphyton and “turbid” waters with great occurrence of phytoplankton or suspended inorganic matter. The herbicide was added at 8 mg L^?1 of the active ingredient (glyphosate) in five mesocosms while five were left as controls (without Roundup^® addition). The estimate of the dissipation rate (k) of glyphosate showed a half-life value of 4.2 days. Total phosphorus significantly increased in treated mesocosms due to Roundup^® degradation what favored eutrophication process. Roundup^® produced a clear delay in periphytic colonization in treated mesocosms and values of the periphytic mass variables (dry weight, ash-free dry weight and chlorophyll a) were always higher in control mesocosms. Despite the mortality of algae, mainly diatoms, cyanobacteria was favored in treated mesocosms. It was observed that glyphosate produced a long term shift in the typology of mesocosms, “clear” turning to “turbid”, which is consistent with the regional trend in shallow lakes in the Pampa plain of Argentina. Based on our findings it is clear that agricultural practices that involve the use of herbicides such as Roundup^® affect non-target organisms and the water quality, modifying the structure and functionality of freshwater ecosystems.     

氟伏沙明和CYP1A2*1F基因多态性对血清奥氮平浓度的影响

目的研究氟伏沙明与细胞色素P450酶1A2(cytochromeP4501A2,CYP1A2)基因*1F位点多态性对精神分裂症患者血清奥氮平浓度的影响。方法入组精神分裂症患者单用奥氮平者(奥氮平组)92例以及奥氮平联用氟伏沙明者(联合组)103例,采集血液,测定CYP1A2*1F基因型以及血清奥氮平浓度,比较2组以及CYP1A2*1F各个基因型间的血清奥氮平浓度差异。结果奥氮平组血清奥氮平浓度(3.39±2.70)mg·L-1·mg-1显著低于联合组(5.14±3.06)mg·L-1·mg-1(t=4.23,P=0.000)。AA型血清奥氮平浓度比CC型低[奥氮平组:(2.46±1.64)mg·L-1·mg-1 vs(4.42±2.88)mg·L-1·mg-1,P<0.05;联合组:(4.06±2.65)mg·L-1·mg-1 vs(6.86±3.25)mg·L-1·mg-1,P<0.01],但是CA型与CC型的差异无统计学显著意义。结论氟伏沙明可升高血清奥氮平浓度;不同基因型个体,血清奥氮平浓度不同;应根据氟伏沙明使用情况和CYP1A2*1F基因型个体化给药。     

The effects of the pharmaceutical carbamazepine on life history characteristics of flat-headed mayflies (Heptageniidae) and aquatic resource interactions

Pharmaceutical pollutants are commonly detected in freshwater ecosystems around the world and have biological effects on aquatic organisms. However, current understanding of the influence this contaminant class has on freshwater communities and ecosystems is lacking. Recently the scientific community has called for research focusing on certain pharmaceuticals due to their ubiquity and potential toxicity. Carbamazepine is one of these pharmaceuticals. To better understand the effect carbamazepine has on life history characteristics of aquatic organisms and consumer-resource interactions, we quantified the influence of carbamazepine on the development, growth and behavior of mayfly nymphs (Stenonema sp.) and the alterations in food consumer-resource interactions between Stenonema and algae (Chaetophora). Microcosms were assembled in a factorial design containing algae and mayfly nymphs native to central Indiana and dosed with environmentally relevant concentrations of carbamazepine. From this ecotoxicological experiment we were able to infer that carbamazepine at 2,000 ng/L influenced the development and behavior of Stenonema nymphs and the body dimensions of adult individuals. However, it appears that carbamazepine does not influence consumer-resource interactions at concentrations found in surface waters. The pharmaceutical carbamazepine may influence the behavior, growth and development of mayflies, which could have significant consequences at the population, community and ecosystem level.     

Effect of butyl paraben on the development and microbial composition of periphyton

Parabens are extensively used as preservatives and bactericides in personal care and other consumer products, and are commonly found in wastewater and surface water as contaminants. However, few data are currently available on the ecotoxicity of parabens. Periphyton biofilm, a widely distributed microbial aggregate of ecological importance in aquatic environment, is frequently used for water quality monitoring, ecological restoration, and toxicity assessment. In this work, the effects of butyl paraben on the development and microbial composition of periphyton biofilm was studied in a laboratory experiment for 32 days using flow through channels. No effect was observed at the environmental relevant concentration level (0.5 μg L^?1) during the experiment. At the highest tested concentration level (5000 μg L^?1), following effects were noted: (1) inhibition on algae growth at the end of the experiment as indicated by the chlorophyll a and total biovolume; (2) inhibition of photosynthetic efficiency on day 24 as suggested by the maximal Photosystem II quantum yield (Fv/Fm); (3) decrease of the algal diversity on day 24 and 32 as reflected by the Pielou and Shannon-Weiner indices. Bacteria were less sensitive than algae in the periphyton biofilm, which showed no difference at all tested concentration levels as illustrated by the Biolog EcoPlates? analysis. Therefore, we conclude that environmental residues of butyl paraben have a very low risk to periphyton in aquatic ecosystems.     

Oxidative stress as a mechanism for toxicity of 2,4-dichlorophenoxyacetic acid (2,4-D): studies with goldfish gills

The effects of exposure to the widely used herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), at environmentally permitted (1 mg L^?1), slightly toxic (10 mg L^?1), and highly toxic (100 mg L^?1) concentrations were analyzed in gills of goldfish, Carassius auratus, a popular fish model for ecotoxicological research. Fish were exposed to the pesticide in water for 96 h and an additional group of fish were treated by the highest 2,4-D concentration and then allowed to recover for further 96 h. Among markers of oxidative stress, goldfish exposure to 2,4-D did not affect carbonyl protein levels in the gills, but fish exposure to 100 mg L^?1 of 2,4-D enhanced lipid peroxide concentrations (by 58 %) and oxidized glutathione levels (by 49 %), the latter also significantly increasing (by 33 %) oxidized/total glutathione ratio. Activities of three enzymes of antioxidant defence also increased under 2,4-D exposure: superoxide dismutase (by 29–35 %), catalase (by 41 %), and glutathione peroxidase (by 19–33 %). Activities of other antioxidant associated enzymes as well as other potential markers of stress (e.g. aminotransferase enzymes, acetylcholinesterase, lactate metabolism) showed little or no response in gills to 2,4-D exposure. However, virtually all affected parameters returned to control values during recovery period. A combination of selected indices of oxidative stress and antioxidant defence, measured in fish gills, may provide to be effective biomarkers to assess environmental hazards of 2,4-D to freshwater ecosystems.