Polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) monitored by tree bark in an E-waste recycling area

To investigate the environmental levels and profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), tree bark samples (n = 22) were collected from Luqiao, an E-waste recycling area, in east China in July 11-13, 2006. The average concentrations of PCDD/Fs, PBDEs, and PCBs determined by isotope dilution-high resolution gas chromatography (HRGC) coupled with high resolution mass spectrometer (HRMS) were 0.1 +/- 0.0, 1.4 +/- 0.2, and 6.5 +/- 0.8 lg g (1) lipid weight, respectively. PCDD/F-toxic equivalent (TEQ, WHO-1998), PCB-TEQs, and total dioxin-like TEQs were 1.3 +/- 0.1, 0.5 +/- 0.0, and 1.8 +/- 0.2 ng g (1) lipid weight, respectively. The profiles of these pollutants in the tree bark were also discussed. Tetra-CDFs, deca-BDE and tri-CBs were the main homologues and accounted for 47% of total PCDD/Fs, 79.3% of total PBDEs, and 33.2% of total PCBs, respectively; As for TEQs, 2,3,4,7,8-PeCDF and PCB126 were the main contributors and accounted for 36% of the total PCDD/F-TEQs and 81.2% of the total PCB-TEQs, respectively. High accumulation of PCDD/Fs, PBDEs, and PCBs detected in the tree bark indicated heavy contaminations of these pollutants in Luqiao area. (C) 2008 Elsevier Ltd. All rights reserved.

The profound effects of microcystin on cardiac antioxidant enzymes, mitochondrial function and cardiac toxicity in rat

Deaths from microcystin toxication have widely been attributed to hypovolemic shock due to hepatic interstitial hemorrhage, while some recent studies suggest that cardiogenic complication is also involved. So far, information on cardiotoxic effects of MC has been rare and the underlying mechanism is still puzzling. The present study examined toxic effects of microcystins on heart muscle of rats intravenously injected with extracted MC at two doses, 0.16LD(50) (14 mu g MC-LReq kg(-1) body weight) and 1LD(50) (87 mu g MC-LReq kg(-1) body weight). In the dead rats, both TTC staining and maximum elevations of troponin I levels confirmed myocardial infarction after MC exposure, besides a serious interstitial hemorrhage in liver. In the 1LD(50) dose group, the coincident falls in heart rate and blood pressure were related to mitochondria dysfunction in heart, while increases in creatine kinase and troponin I levels indicated cardiac cell injury. The corresponding pathological alterations were mainly characterized as loss of adherence between cardiac myocytes and swollen or ruptured mitochondria at the ultrastructural level. MC administration at a dose of 1LD(50) not only enhanced activities and up-regulated mRNA transcription levels of antioxidant enzymes, but also increased GSH content. At both doses, level of lipid peroxides increased obviously, suggesting serious oxidative stress in mitochondria. Simultaneously. complex I and III were significantly inhibited, indicating blocks in electron flow along the mitochondrial respiratory chain in heart. In conclusion, the findings of this study implicate a role for MC-induced cardiotoxicity as a potential factor that should be considered when evaluating the mechanisms of death associated with microcystin intoxication in Brazil. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Chronic effects of water-borne PFOS exposure on growth, survival and hepatotoxicity in zebrafish: A partial life-cycle test

Perfluorooctane sulfonate (PFOS) is widely distributed and persistent in the environment and wildlife. The main aim of this study was to investigate the impact of long-term exposure to low concentrations of PFOS in zebrafish. Zebrafish fry (F-0, 14d post-fertilization, dpf) were exposed via the water for 70d to 0 (control), 10, 50 and 250 mu g L-1 PFOS, followed by a further 30d to assess recovery in clean water. The effects on survival and growth parameters and liver histopathology were assessed. Although growth suppression (weight and length) was observed in fish treated with high concentrations PFOS during the exposure period, no mortality was observed throughout the 70d experiment. Embryos and larvae (F-1) derived from maternal exposure suffered malformation and mortality. Exposure to 50 and 250 mu g L-1 PFOS could inhibit the growth of the gonads (GSI) in the female zebrafish. Histopathological alterations, primary with lipid droplets accumulation, were most prominently seen in the liver of males and the changes were not reversible, even after the fish were allowed to recover for 30d in clean water. The triiodothyronine (T-3)) levels were not significantly changed in any of the exposure groups. Hepatic vitellogenin (VTG) gene expression was significantly up-regulated in both male and female zebrafish, but the sex ratio was not altered. The overall results suggested that lower concentrations of PFOS in maternal exposure could result in offspring deformation and mortality. (c) 2008 Elsevier Ltd. All rights reserved.

Changes in plasma thyroid hormones and cortisol levels in crucian carp (Carassius auratus) exposed to the extracted microcystins

The endocrine response of crucian carp injected intraperitoneally with extracted microcystins (MC) was investigated in this study. Fish were injected intraperitoneally either with 0.75% NaCl (control) and Microcystis extract corresponding to 150 and 600 mu g microcystins per kg body weight. The plasma levels of triiodothyronine (T-3), thyroxine (T-4), free triiodothyronine (FT3), free thyroxine (FT4), and cortisol were determined at 0, 1, 3, 12, 24. and 48 h post-administration of MC-containing extract. Treated fish displayed abnormal behaviors, Such as a startle response and disoriented swimming, as well as changes in ventilation rates. Plasma cortisol concentrations of fish in both dose groups significantly increased after administration of extracted MC and remained high throughout the experiment, which suggested that MC elicited a stress response in treated fish. The profiles of cortisol changes in treated fish appeared to be dose dependent, indicating that fish in the high dose group experienced greater MC-incluced disturbance. Mortality occurred after 12 h in the high dose group. Plasma levels of T-4, T-3, FT4, and FT3 did not vary significantly between the control fish. In contrast to this, fish exposed to MC-containing extract showed significant declines in T-3, FT4, and FT3 levels in a dose-depenclent manner throughout the experiment. Plasma T4 levels, however, did not vary significantly in the low dose group, whereas they decreased significantly it 48 h post injection in the high dose group. This study demonstrates that administration of microcystins-containing extract causes a stress response and reduces the plasma levels of thyroid hormones in crucian carp. These results illustrate that microcystins exerted potent effects on the endocrine system of crucian carp, through activating their hypothalamus-pituitary- interrenal axis and disturbing thyroid function. (c) 2008 Elsevier Ltd. All rights reserved.

Elevated levels of urinary 8-hydroxy-2'-deoxyguanosine in male electrical and electronic equipment dismantling workers exposed to high concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans, polybrominated diphenyl ethers, and polychlorinated biphenyls

To investigate the occupational exposure levels to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), indoor dust (n = 3) in workshops and hair samples from male workers (n = 64) were collected at two electrical and electronic equipment waste (E-waste) dismantling factories located in the LQ area in east China in July 11-13, 2006. Pre- and postworkshift urines (64 of each) were also collected from the workers to study oxidative damage to DNA using 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker. The concentrations of PCDD/Fs, PCDD/F-WHO-TEQs, PBDEs, PCBs and PCB-WHO-TEQs were (50.0 +/- 8.1) x 10(3), 724.1 +/- 249.6, (27.5 +/- 5.8) x 10(6), (1.6 +/- 0.4) x 10(9), (26.2 +/- 3.0) x 10(3) pg/g dry weight (dw) in dust, and (2.6 +/- 0.6) x 10(3), 42.4 +/- 9.3, (870.8 +/- 205.4) x 10(3), (1.6 +/- 0.2) x 10(6), 41.5 +/- 5.5 pg/g dw in hair, respectively. The homologue and congener profiles in the samples demonstrated that high concentrations of PCDD/Fs, PBDEs, and PCBs were originated from open burning of E-waste. The 8-OHdG levels were detected at 6.40 +/- 1.64 mu mol/mol creatinine in preworkshift urines. However, the levels significantly increased to 24.55 +/- 5.96 mu mol/mol creatinine in postworkshift urines (p < 0.05). Then, it is concluded that there is a high cancer risk originated from oxidative stress indicated by the elevated 8-OHdG levels in the E-waste dismantling workers exposed to high concentrations of PCDD/Fs, PBDEs, and PCBs.

Dietary phosphorus requirement of juvenile black seabream, Sparus macrocephalus

A growth trial was conducted to estimate the optimum requirement of dietary available phosphorus (P) for black seabream (Sparus macrocephalus) in indoor net cages (1.5x1.0x1.0 m). Triplicate groups of black seabream (11.45 +/- 0.02 g) were fed diets containing graded levels (0.18, 0.36, 0.54, 0.72, 0.89 and 1.07%) of available P to satiation for 8 weeks. The basal diet (diet 1), containing 0.18% available P, was supplemented with graded levels of monosodium phosphate (NaH2PO4 2H(2)O) to formulate five experimental diets. The fish were fed twice daily (08:00 h and 16:00 h) and reared in seawater (salinity, 26-29 g l(-1)) at a temperature of 28 +/- 1 degrees C. Dissolved oxygen during the experiment was above 5 mg l(-1). The specific growth rate (SGR), weight gain (WG), feed efficiency (FE) and protein efficiency ratio (PER) were all significantly improved by dietary phosphorus up to 0.54% (P<0.05) and then leveled off beyond this level. Hepatosomatic index (HSI) was inversely correlated with dietary phosphorus levels (P< 0.05). Efficiency of P utilization stabled in fish fed diets containing 0.18%-0.54% available P and then decreased dramatically with further supplementation of dietary phosphorus. Body composition analysis showed that the whole-body lipid, ash, calcium and phosphorus contents were all significantly affected by dietary available P concentration (P<0.05), however, no significance were found in whole-body calcium/phosphorus (Ca/P) ratios among all the treatments (P>0.05). Dietary phosphorus levels also affected the mineralization of vertebrae, skin and scale (P<0.05). Ca/P ratios in vertebrae and scale were not influenced by dietary P supplementation, while skin Ca/P ratio increased statistically with dietary available P levels (quadratic effect, P<0.001). The blood chemistry analysis showed that dietary available P had distinct effects on enzyme activities of alkaline phosphatase (ALP) and plasma lysozyme (LSZ), as well as contents of triacyglycerol (TG) and total cholesterol (T-CHO) (P<0.05). Broken-line analysis showed maximum weight gain (WG) was obtained at dietary available P concentrations of 0.55%. Quadratic analysis based on P contents in whole fish, vertebrae or scale indicated that the requirements were 0.81, 0.87 and 0.88%, respectively. Signs of phosphorus deficiency were characterized by poor growth, slightly reduced mineralization and an increase in body lipid content. (C) 2008 Published by Elsevier B.V.

Enzyme-linked immunosorbent assay of changes in serum levels of growth hormone (cGH) in common carps (Cyprinus carpio)

The aim of the present study was to purify the common native carp growth hormone (ncGH), produce monoclonal antibodies (mAbs) to common native carp growth hormone (ncGH), and further enhance the sensitivity of enzyme-linked immunosorbent assays (ELISA) for ncGH. Additionally, we investigated changes in serum ncGH levels in carps raised in different environmental conditions. The recombinant grass carp (Ctenopharyngodon idella) growth hormone was purified and used as antigen to immunize the rabbit. The natural ncGH was isolated from the pituitaries of common carp. SDS-PAGE and Western blot utilizing the polyclonal anti-rgcGH antibody confirmed the purification of ncGH from pituitaries. Purified ncGH was then used as an immunogen in the B lymphocyte hybridoma technique. A total of 14 hybridoma cell lines (FMU-cGH 1-14) were established that were able to stably secrete mAbs against ncGH. Among them, eight clones (FMU-cGH1-6, 12 and 13) were successfully used for Western blot while nine clones (FMU-cGH 1-7, 9 and 10) were used in fluorescent staining and immunohistochemistry. Epitope mapping by competitive ELISA demonstrated that these mAbs recognized five different epitopes. A sensitive sandwich ELISA for detection of ncGH was developed using FMU-cGH12 as the coating mAb and FMU-cGH6 as the enzyme labeled mAb. This detection system was found to be highly stable and sensitive, with detection levels of 70 pg/mL. Additionally, we found that serum ncGH levels in restricted food group and in the net cage group increased 6.9-and 5.8-fold, respectively, when compared to controls, demonstrating differences in the GH stress response in common carp under different living conditions.

Oxidative damage in unfertilized eggs of Chinese rare minnow (Gobiocypris rarus) exposed to nonylphenol

In the present study, female Chinese rare minnows (Gobiocypris rarus) were used as in vivo models and exposed to nonylphenol (NP) at concentrations of 1 to 200 mu g/L for 21 d under semistatic conditions. Molecular biomarkers of oxidative stress were measured in unfertilized eggs and included reactive oxygen species (ROS), lipid peroxidation products (thiobarbituric acid-reactive substances [TBARS] and protein carbonyl), superoxide dismutase activity, and glutathione. Cathepsin D activity as an indicator of egg viability also was assayed. Nonylphenol induced ROS formation in unfertilized eggs in all exposed groups compared to the controls. The levels of protein carbonyl and TBARS in unfertilized eggs were significantly increased (p < 0.05) at 10 to 200 and 100 to 200 mu g/L, respectively. Good positive correlations were shown between ROS induction and levels of TBARS and protein carbonyl in eggs (R = 0.918, p < 0.05 and R = 0.784, p < 0.05, respectively). Superoxide dismutase activity in eggs was significantly inhibited (p < 0.05) in the 50 to 200 mu g/L exposure groups. Glutathione levels in eggs were significantly depleted (p < 0.05) at 100 to 200 mu g/L concentrations. In addition, ROS induction resulted in oxidative damage to lipid and protein in chorions. Significant reductions (p < 0.05) of the protein and lipid contents in chorions were both found in the 50 to 200 mu g/L exposure groups. A previous study found that NP exposure could lead to chorion thinning in zebra fish. Thus, the reductions in protein and lipid contents in chorion could be the reason for chorion thinning by NP exposure. Meanwhile, cathepsin D activity was significantly inhibited (p < 0.05) in all exposure groups. The results demonstrated that NP-induced oxidative stress could damage the chorion of unfertilized eggs and lead to a decline in gamete quality in female Chinese rare minnow.

Effect of dietary carbohydrate-to-lipid ratios on growth and feed utilization in Chinese longsnout catfish (Leiocassis longirostris Gunther)

An 8-week growth trial was carried out in a semi-recirculation system at 26 +/- 0.5 degrees C to investigate the optimal dietary carbohydrate-to-lipid (CHO:L) ratio for carnivorous Chinese longsnout catfish (Leiocassis longirostris Gunther). Triplicate tanks of fish were assigned to each of five isocaloric and isonitrogenous diets with different carbohydrate-to-lipid ratios (0.75, 1.48, 1.98, 2.99 and 5.07). The results showed that a higher specific growth rate (SGR) and feed rate (FR) were observed in the fish fed diet ratios of 1.98 CHO:L (P < 0.05). Overloading dietary carbohydrate (5.07 CHO:L ratio) caused skeletal malformations. Apparent digestibility of dry matter (ADC(d)) significantly increased with dietary CHO:L ratio (P < 0.05), while significantly higher apparent digestibility of protein (ADC(p)) and apparent digestibility of energy (ACD(e)) was observed only in the 1.98 CHO:L group (P < 0.05). Whole body contents of dry matter, lipid and energy significantly increased as the CHO:L ratio decreased (P < 0.05). The hepatosomatic index (HSI) was highest at 1.98 CHO:L ratio (P < 0.05). Highest dietary CHO:L ratio resulted in lower liver glycogen, liver lipid, plasma glucose and plasma triacylglycerol (P < 0.05), whereas there was no significant difference in plasma total cholesterol (P > 0.05). High dietary CHO:L ratio caused pathological changes in fish morphology and liver histology. Based on maximum growth, the optimal carbohydrate-to-lipid ratio was 1.98 for Chinese longsnout catfish.

In situ studies on physiological and biochemical responses of four fishes with different trophic levels to toxic cyanobacterial blooms in a large Chinese lake

Physiological and biochemical responses of four fishes with different trophic levels to toxic cyanobacterial blooms were studied in a large net cage in Meiliang Bay, a hypereutrophic region of Lake Taihu. We sampled four fishes: the phytoplanktivorous Hypophthalmichthys molitrix and Aristichthys nobilis, the omnivorous Carassius auratus, and the carnivorous Culter ilishaeformis. Alterations of the antioxidant (GSH) and the major antioxidant enzymes (CAT, SOD, GPx, GST) in livers were monitored monthly, and the ultrastructures of livers were compared between the bloom and post-bloom periods. During the cyanobacterial blooms, the phytoplanktivorous fishes displayed only slight ultrastructural changes in liver, while the carnivorous fish presented the most serious injury as swollen endomembrane system and morphologically altered nuclei in hepatocytes. Biochemically, the phytoplanktivorous fishes possessed higher basal GSH concentrations and better correlations between the major antioxidant enzymes in liver, which might be responsible for their powerful resistance to MCs. This article provided physiological and toxicological evidences for the possible succession of fish communities following occurrence of toxic cyanobacterial blooms and also for the applicability of using phytoplanktivorous fish to counteract toxic cyanobacterial blooms in natural waters. (C) 2007 Elsevier Ltd. All rights reserved.

Effect of dietary supplementation of vitamins A, D-3, E, and C on yearling rice field eel, Monopterus albus: Serum indices, gonad development, and metabolism of calcium and phosphorus

The objective of this study was to determine the effect of dietary vitamins A, D-3, E, and C on the gonad development, lipid peroxidation, and immune response of yearling rice field eel, Monopterus albus. A 6-wk feeding trial was designed according to an L-16(4(5)) orthogonal design, in which four vitamins, each at four supplementation levels, were arranged. Sixteen diets were mixed with the different vitamin levels and randomly assigned to 16 groups of fish. Increasing dietary vitamin E supplementation level significantly (P <= 0.05) increased the gonadosomatic index and lowered the serum content of malondialdehyde of rice field eel. Increasing dietary vitamin A and C levels also showed similar effect, but the differences were not statistically significant. Serum immunoglobulin M content increased significantly (P <= 0.01) as dietary vitamin C supplementation levels increased. The concentrations of calcium in bones showed significant (P <= 0.05) trend with vitamin D-3 and A supplementation levels, but the bone phosphorus content was not affected by the dietary vitamin levels.

Response of growth and fatty acid compositions of Nannochloropsis sp to environmental factors under elevated CO2 concentration

Nannochloropsis sp. was grown with different levels of nitrate, phosphate, salinity and temperature with CO2 at 2,800 mu l l(-1). Increased levels of NaNO3 and KH2PO4 raised protein and polyunsaturated fatty acids (PUFAs) contents but decreased carbohydrate, total lipid and total fatty acids (TFA) contents. Nannochloropsis sp. grew well at salinities from 22 to 49 g l(-1), and lowering salinity enhanced TFA and PUFAs contents. TFA contents increased with the increasing temperature but PUFAs contents decreased. The highest eicosapentaenoic acid (EPA, 20:5 omega 3) content based on the dry mass was above 3% under low N (150 mu M NaNO3) or high N (3000 mu M NaNO3) condition. Excessive nitrate, low salinity and temperature are thus favorable factors for improving EPA yields in Nannochloropsis sp.

Responses of antioxidant system in Arabidopsis thaliana suspension cells to the toxicity of microcystin-RR

Microcystins are cyclic heptapeptide hepatoxins produced by many species of cyanobacteria. The toxic effects and mechanism of microcystins on animals have been well studied both in vivo and in vitro. It was also reported that microcystins had adverse effects on plants. However, to our knowledge, there is no information about the toxic effects and mechanism of microcystins on plant suspension cells. In this study, Arabidopsis thaliana suspension cells were exposed to a range dose of microcystin-RR. Lipid peroxidation, a main manifestation of oxidative damage, was studied and a time- and dose-dependent increase in malondiadehyde was observed. In contrast, glutathione (GSH) levels in the cells decreased after 48 h treatment with 1 and 5 mg/L of microcystin-RR. The activities of superoxide dismutase (SOD) and catalase (CAT) increased significantly after 48 h exposure to I and 5 mg/L of microcystin-RR, but glutathione S-transferase (GST) activity showed no difference compared with the control. These results clearly indicate that microcystin-RR is able to cause oxidative damage in A. thaliana suspension cells. Decrease of GSH content and increases of SOD and CAT activities reveal that the antioxidant system may play an important role in eliminating or alleviating the toxicity of microcystin-RR. The possible toxicity mechanism of microcystin-RR on the A. thaliana suspension cells is also discussed in this paper. (C) 2005 Elsevier Ltd. All rights reserved.

Effects of polyaluminum chloride and copper sulfate on phosphorus and UV254 under different anoxic levels

Experimental sediments and water from shallow, eutrophic Dianchi Lakes were treated in a controlled laboratory microcosm using different chemicals under different anoxic levels. This study revealed that the polyaluminum chloride (PAC) was able to inhibit the phosphorus release and decrease the UV254 value at any anoxic level. When the DO concentrations were between 0.76-0.95 mg(.) L-1, the UV(254)value, total phosphorus (TP), and total dissolved phosphorus (TDP) in the water column were decreased by 71.93%, 87.12% and 64.24% respectively. The UV254, TP, and TDP were also decreased by 72.94%, 70.87% and 50.76% respectively at the levels of 4.56-5.32mg(.)L(-1) of DO concentrations. The treatment effects of TP and TDP in the water column using copper sulfate however were not as efficient as the PAC treatment. The UV254 value was increased with the addition of copper sulfate at every anoxic level tested but the chlorophyll-a (Chl-a) content was decreased rapidly and efficiently by copper sulfate more than the treatment by PAC. When the DO concentrations were 0.76-0.86mg(.)L(-1) and 4.75-5.14mg(.)L(-1), the Chl-a concentrations were decreased by 84.87% and 75.07% respectively through copper sulfate treatment. With additions of PAC and copper sulfate, the phosphorus fractions in sediments were shifted forward to the favorable shapes that have little ability of release. The TP concentrations in sediments were increased after treatment via PAC and copper sulfate. Under anoxic conditions, most of the BD-P (Fe-P) to NaOH-P (Al-P) was converted using the recommended PAC dose in BD-P rich sediment. Similar to the PAC, the copper sulfate also could flocculate the exchange phosphorus from sediment to overlying water. Overall though, the effects of copper sulfate treatment were not better than that of the PAC.

Positive effects of continuous low nitrate levels on growth and photosynthesis of Alexandrium tamarense (Gonyaulacales, Dinophyceae)

The growth and photosynthesis of Alexandrium tamarense (Lebour) Balech in different nutrient conditions were investigated. Low nitrate level (0.0882 mmol/L) resulted in the highest average growth rate from day 0 to day 10 (4.58 x 10(2) cells mL(-1) d(-1)), but the lowest cell yield (5420 cells mL(-1)) in three nitrate level cultures. High nitrate-grown cells showed lower levels of chlorophyll a-specific and cell-specific light-saturated photosynthetic rate (P-m(chl a) and P-m(cell)), dark respiration rate (R-d(chl a) and R-d(cell)) and chlorophyll a-specific apparent photosynthetic efficiency (alpha(chl a)) than was seen for low nitrate-grown cells; whereas the cells became light saturated at higher irradiance at low nitrate condition. When cultures at low nitrate were supplemented with nitrate at 0.7938 mmol/L in late exponential growth phase, or with nitrate at 0.7938 mmol/L and phosphate at 0.072 mmol/L in stationary growth phase, the cell yield was drastically enhanced, a 7-9 times increase compared with non-supplemented control culture, achieving 43 540 cells mL(-1) and 52 300 cells mL(-1), respectively; however, supplementation with nitrate in the stationary growth phase or with nitrate and phosphate in the late exponential growth phase increased the cell yield by no more than 2 times. The results suggested that continuous low level of nitrate with sufficient supply of phosphate may facilitate the growth of A. tamarense.