Showing papers in "Environmental Toxicology in 2007"
TL;DR: Cd exposure induces oxidative stress in Camellia sinensis and the upregulation in transcript levels of glutathione metabolic genes except GST have suggested the role of these enzymes in the protection of plants from high level Cd exposure.
Abstract: Glutathione, a tripeptide with sulfhydryl (-SH) group is a very crucial compound primarily
involved in redox balance maintenance of the cellular environment. In this study, we monitored the influence
of Cd exposure on the transcript levels of glutathione metabolic genes in bud tissues, the youngest
leaf, of Camellia sinensis L. In addition, some physiochemical parameters were also studied. Cd exposure
decreased chlorophyll and protein contents, while increase was observed in lipid peroxidation upon Cd
treatments. These changes were found to be concentration and duration dependent, indicating the occurrence
of oxidative stress upon Cd exposure. The transcript levels of glutathione biosynthetic genes viz. �-
glutamylcysteine synthetase (�-ECS) and glutathione synthetase (GSHS) increased upon Cd exposure.
Furthermore, transcript levels of glutathione reductase (GR), an enzyme involved in reduction of oxidized
glutathione (GSSG) to reduced glutathione (GSH), also showed upregulation on Cd exposure. However,
the transcript levels of glutathione-S-transferase (GST), an enzyme involved in forming metal–GSH complex
and help in sequestration of high levels of metal ions to vacuole, did not show any change on Cd
treatment. This study document that Cd exposure induces oxidative stress in Camellia sinensis and the
upregulation in transcript levels of glutathione metabolic genes except GST have suggested the role of
these enzymes in the protection of plants from high level Cd exposure. # 2007 Wiley Periodicals, Inc. Environ
Toxicol 22: 368–374, 2007.
177 citations
TL;DR: A difference in lung pathological lesions induced by instilled MWCNTs and inhaled ones is demonstrated, which may be due to the different size and distribution of aggregations of M WCNTs in lung.
Abstract: The pathological lesions induced by multiwalled carbon nanotubes (MWCNTs) in bronchi and alveoli of mice were studied by intratracheal instillation and inhalation. In instillation groups, the dose was 0.05 mg MWCNTs/mouse. Similar size clumps of MWCNTs were distributed in bronchi and alveoli. The clumps led to inflammation to the lining wall of bronchi and severe destruction to alveolar netted structure around them. In the inhalation groups, the mice were exposed to aerosolized MWCNTs with mean concentration of 32.61 mg/m(3), the intralung deposition dose were roughly 0.07, 0.14, and 0.21 mg in the 8-day group, 16-day group, and 24-day group, respectively. Most of aggregations of MWCNTs in the alveoli were smaller than that in bronchi. The aggregations induced proliferation and thickening of alveolar walls. With the exception of these moderate pathological lesions, the general alveolar structure was still remained. The preliminary study demonstrated a difference in lung pathological lesions induced by instilled MWCNTs and inhaled ones, which may be due to the different size and distribution of aggregations of MWCNTs in lung. (C) 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 415-421, 2007.
171 citations
TL;DR: The uptake of two microcystins (MC‐LR and MC‐LF) as well as MC‐LR within a cyanobacterial crude extract in several important agricultural plants is presented and good correlation was shown between toxin uptake and lipid peroxidation in the seedlings.
Abstract: Plants used for agriculture may come into contact with cyanobacterial toxins via spray irrigation when surface water bodies containing cyanobacteria are used as the water source. As many of the bloom forming cyanobacteria are known to produce a variety of toxins, the possibility of uptake of toxins in these plants seems possible. With this study the uptake of two microcystins (MC-LR and MC-LF) as well as MC-LR within a cyanobacterial crude extract in several important agricultural plants is presented. Especially high uptake values in roots of alfalfa and wheat, using an ELISA kit for microcystin detection, is shown. In general, concentrations in the shoot occur at a much lower level than in the root. The amount of toxin is correlated with cellular damage in the seedlings using lipid peroxidation as an indicator. Good correlation was shown between toxin uptake and lipid peroxidation in the seedlings. The exposure of agriculturally important crop plants to cyanobacterial toxins via spray irrigation or watering is a potential concern for human health, as these toxins may accumulate in plant tissues and may therefore be carried through the food chain.
118 citations
TL;DR: It is demonstrated that it is essential to assess the toxicity of the metabolites formed to complete a more comprehensive study of the environmental impact of a polluting agent.
Abstract: The potential toxicity of several herbicides-alachlor, diuron and its photo and biotransformation products, glyphosate and its metabolite aminomethyl phosphonic acid (AMPA)-to nontarget cells was assessed using two microorganisms frequently used in ecotoxicology, Vibrio fischeri and Tetrahymena pyriformis. Toxicity assays involved the Microtox® test, the T. pyriformis population growth impairment test employing three different processes (flasks, tubes, microplates), and the T. pyriformis nonspecific esterase activities test. Several IC50 or EC50 values are reported for each molecule. Alachlor exerted a toxic effect on the two nontarget cells used. The results for diuron and its photo and biotransformation products indicated that most of the metabolites presented nontarget toxicity higher than that of diuron. Glyphosate and AMPA had a less negative effect on T. pyriformis than on V. fischeri. Nevertheless, in all cases, glyphosate was found to be more toxic than AMPA. Comparison analysis of the sensitivity of the different tests showed that, in general, tests using the eukaryotic cell (7: pyriformis} were more sensitive than test using the prokaryotic cell (V. fischeri), and that a population growth criterion is more sensitive than an enzymatic criterion. The three different processes that could be used to evaluate effects on population growth rate were equally sensitive for the herbicides tested. A significant correlation between toxicity data and the hydrophobicity of the chemicals could only be established with the growth population test. This study demonstrates that it is essential to assess the toxicity of the metabolites formed to complete a more comprehensive study of the environmental impact of a polluting agent.
115 citations
TL;DR: Lead toxicity was dosage dependent and become evident in gross morphological malformations, followed by histopathological changes, and early life stages of the African catfish C. gariepinus are a very sensitive bioassay for aquatic lead pollution.
Abstract: The effect of lead exposure (100, 300, and 500 μg/L lead nitrate) on embryos of the African catfish Clarias gariepinus were examined by gross morphology and histopathology. Exposition to lead nitrate caused a progressively longer delay in hatching and also reduced the percentage of embryos, which successfully completely hatch from 75% in the control group to 40% in the group exposed to 500 μg/L lead. Categories of gross morphological abnormalities comprised four major ones (irregular head shape, pericardial edema, yolk sac edema, and notochordal defect) and two minor deformations (finfold defect and reduction of pigmentation). The frequencies of recorded morphological malformations increased significantly (P < 0.05) with increasing lead concentration in all stages. Four histopathological categories comprising notochordal defect, gill malformation, eye malformation, and detached skin were recorded. All these malformations were recorded only in the embryos exposed to 300 and 500 μg/L lead. The degrees of histological lesions increased with increasing lead concentration and with length of exposure time. Mean concentrations of lead in the whole embryos were measured and the lowest concentrations of lead were recorded in the control groups (0.3–1.0 μg/g wet wt). Accumulated lead increased significantly (P < 0.05) with increasing dose in all stages. Accumulation of lead in the chorion suggests that the chorion acts as an effective barrier protecting the embryo. Low impact of lead on prehatching stages may be related to both the protective capacity of the chorion and the ability of the perivitelline fluid to concentrate lead. The present results show that (i) lead toxicity was dosage dependent and become evident in gross morphological malformations, followed by histopathological changes, and (ii) early life stages of the African catfish C. gariepinus are a very sensitive bioassay for aquatic lead pollution. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 375–389, 2007.
106 citations
TL;DR: It is suggested that CYN may be an important cyanobacterial toxin in German water bodies and that further data are needed to assess this, and analyses of phytoplankton data suggest Aphanizomenon sp.
Abstract: Received 15 February 2006; revised 12 June 2006; accepted 20 July 2006ABSTRACT: The frequent occurrence of the cyanobacterial toxin cylindrospermopsin (CYN) in the (sub)-tropics has been largely associated with cyanobacteria of the order Nostocales of tropical origin, in partic-ular Cylindrospermopsis raciborskii. C. raciborskii is currently observed to spread northwards into temper-ate climatic zones. In addition, further cyanobacteria of the order Nostocales typically inhabiting waterbodies in temperate regions are being identified as CYN-producers. Therefore, data on the distribution ofCYN in temperate regions are necessary for a first assessment of potential risks due to CYN in water usedfor drinking and recreation. A total of 127 lakes situated in the north-eastern part of Germany were investi-gated in 2004 for the presence of the toxin CYN and the phytoplankton composition. The toxin could bedetected in half of the lakes (n ¼ 63) and in half of 165 samples (n ¼ 88). Concentrations reached up to73.2 g CYN/g DW. CYN thus proved more widely distributed than previously demonstrated. The analysesof phytoplankton data suggest Aphanizomenon sp. and Anabaena sp. as important CYN producers inGermany, and confirm recent findings of Aphanizomenon flos-aquae as CYN-producing species fre-quently inhabiting water bodies in temperate climatic regions. The data shown here suggest that CYNmay be an important cyanobacterial toxin in German water bodies and that further data are needed toassess this.
98 citations
TL;DR: This study evaluated the acute toxicity sensitivity profile of Tigriopus japonicus against 12 common toxic substances including six endocrine disrupting chemicals (EDCs), three biocides and three trace metals and found that T. Japonicus was particularly sensitive to most of the EDCs, but relatively less sensitive to molinate (a thiocarbate herbicide).
Abstract: Marine copepods have recently been recognized as important organisms in ecotoxicity testing for regulatory purposes. The harpacticoid copepod Tigriopus japonicus has a wide geographical distribution along the coast in the Western Pacific including Japan, South Korea, Taiwan, and Hong Kong. This study evaluated the acute toxicity sensitivity profile of Tigriopus japonicus against 12 common toxic substances including six endocrine disrupting chemicals (EDCs), three biocides and three trace metals. Through standard acute toxicity test procedures, toxicity endpoints LC(50), LC(10), and no observed effect concentration (NOEC) of each chemical were obtained. Although T. japonicus depicted different sensitivities towards different chemicals, a dose-response relationship was consistent in all cases. T. japonicus was particularly sensitive to most of the EDCs, but relatively less sensitive to molinate (a thiocarbate herbicide). Across all tested chemicals, tributyltin (TBT) was the most toxic to the copepod with the LC(50), LC(10), and NOEC of 0.05, 0.03, and 0.02 mg/L, respectively. A comparison made with available data on acute toxicities of these chemicals to other marine copepod species revealed that T. japonicus is generally more sensitive to EDCs and in particular to TBT. We, therefore, strongly advocate that T. japonicus shall be adopted as a benchmark marine species for routine ecotoxicity testing and ecotoxicological studies in Western Pacific coasts.
94 citations
TL;DR: Heavy metal concentrations in Mytilus galloprovincialis are suitable biomonitors to investigate the contamination levels of heavy metals pollution face a different human activity in this coastal area of the Atlantic coast.
Abstract: Heavy metal concentrations of mercury, cadmium, lead, zinc, cooper, nickel, manganese, and chromium in Mytilus galloprovincialis were investigated to provide information on pollution of Safi coastal area, since these metals have the highest toxic potential. The concentration of Hg and Pb was determined by AFS and ICP-MS methods, respectively, whilst the remaining metals (Cd, Cr, Cu, Mn, Zn, and Ni) were quantified by AAS. High lead, cadmium, chromium, and mercury levels were registered in tissue samples collected from two stations near the Jorf Lihoudi and Safi city, while elevated concentration of manganese and zinc (14.70-25.30 mg kg(-1) and 570-650 mg kg(-1) dry wt, respectively) were found in mussel specimens from Cap Cantin. The high levels of nickel found respectively in the areas near the industrial area being of concern in terms of environmental health need frequent monitoring. The metal concentrations recorded at the clean stations may be considered as useful background levels to which to refer for comparison within the Atlantic coast. M. galloprovincialis are suitable biomonitors to investigate the contamination levels of heavy metals pollution face a different human activity in this coastal area of the Atlantic coast.
87 citations
TL;DR: It is suggested that ingestion of boron in the drinking water decreases the incidence of cervical cancer‐related histopathological findings, and these findings should be validated by other researchers.
Abstract: Recent evidence indicates that boron and borates may have anticarcinogenic properties. In this study, we have investigated the incidence of adverse cytological findings in cervical smears and the micronucleus (MN) frequency in women living in boron-rich and boron-poor regions. Cervical smears were prepared from 1059 women with low socioeconomic status; 472 of the women lived in relatively boron-rich rural areas, while 587 lived in relatively boron-poor regions. The average and standard deviation values for the age of the women screened with the cervical Pap smear test were 41.55 +/- 8.38. The mean dietary intake of boron was 8.41 mg/day for women from the boron-rich regions, and 1.26 mg/day for women living in the boron-poor regions (P 0.05). Also, there were no significant correlations between age and MN frequency for women from both the boron-rich (r = 0.133, P = 0.48, P > 0.05) and boron-poor (r = -0.033, P = 0.861, P > 0.05) regions. The results suggest that ingestion of boron in the drinking water decreases the incidence of cervical cancer-related histopathological findings. There was no correlation between the pathological findings from the cervical smears and buccal cell MN frequency suggesting that the two study populations were exposed equally to gentotoxic agents. Nonetheless, cervical cancer-related histopathological findings should be validated by other researchers.
85 citations
TL;DR: It was concluded that due to high metal accumulation coupled with defense potential, the plant appears to have a potential for its use as phytoremediator species of aquatic environments.
Abstract: To evaluate the biological effects of wastewater samples containing heavy metals, the effects of metal Cd (II) and As (V) were studied on Spirodela polyrrhiza L. The plants were exposed at metal concentrations 0.1, 0.5, 1, 2 microM of Cd (II) and 1, 5, 10, 20 microM of As (V) for a period of 1, 4, 7 d (day) alone and in combination of both. Plants accumulated 1855 mg kg(-1) dw (dry weight) Cd and 1230 mg kg(-1) dw As after 7 d in alone, whereas it was 885 mg kg(-1) dw Cd and 865 mg kg(-1) dw As in combination. The toxicological parameters such as fresh biomass, photosynthetic pigments, and total protein contents increased up to 2 microM of Cd (II) after 1 d and 10 microM of As (V) after 4 d with respect to control (Hormesis effect), followed by gradual decline at higher concentrations and duration. In case of Cd (II) a maximum decrease of 58% in protein content, 62% in fresh biomass, and 78% in total chlorophyll was observed at 2 microM, whereas, with As (V) 38% decrease in protein content, 34% in fresh biomass, and 52% in total chlorophyll was shown at 20 microM after 7 d. The metal tolerance strategy against metal induced reactive oxygen species adopted by the plants was investigated with reference to nonprotein thiols (NP-SH), cysteine, and ascorbic acid. The results of combined treatment revealed reduced toxicity at the level of fresh biomass, protein content, and chlorophyll; however, the amount of nonenzymatic antioxidant did not significantly (P = 0.172) increase as compared to alone treatment. Finally, it was concluded that due to high metal accumulation coupled with defense potential, the plant appears to have a potential for its use as phytoremediator species of aquatic environments.
85 citations
TL;DR: It is plausible to infer that cadmium in the presence of hydrogen peroxide causes DNA damage probably by the formation of hydroxyl ions, as shown in the conversion of covalently closed circular double‐stranded pBR 322 DNA.
Abstract: Cadmium is an environmental toxicant, which causes cancer in different organs. It was found that it damages DNA in the various tissues and cultured cell lines. To investigate the mechanism of DNA damage, we have studied the effect of cadmium-induced DNA damage in plasmid pBR322 DNA, and the possible ameliorative effects of antioxidative agents under in vitro conditions. It was observed that cadmium alone did not cause DNA damage. However, it caused DNA damage in the presence of hydrogen peroxide, in a dose dependent manner, because of production of hydroxyl radicals. Findings from this study show the conversion of covalently closed circular double-stranded pBR 322 DNA to the open circular and linear forms of DNA when treated with 10 μM cadmium and various concentrations of H2O2. The conversion was due to nicking in DNA strands. The observed rate of DNA strand breakage was dependent on H2O2 concentration, temperature, and time. Metallothionein I failed to prevent cadmium-induced DNA nicking in the presence of H2O2. Of the two antioxidant enzymes (catalase and superoxide dismutase) studied, only catalase conferred significant (50–60%) protection. EDTA and DMSO exhibited protection similar to catalase, while mannitol showed only about 20% protection against DNA damage. Ethyl alcohol failed to ameliorate cadmium-induced DNA strands break. From this study, it is plausible to infer that cadmium in the presence of hydrogen peroxide causes DNA damage probably by the formation of hydroxyl ions. These results may indicate that cadmium in vivo could play a major role in the DNA damage induced by oxidative stress. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 144–151, 2007.
TL;DR: Monitoring of Mediterranean drinking water reservoirs needs to be intensified during winter, a season usually considered to be less prone to the formation of cyanobacterial blooms.
Abstract: Sicilian reservoirs constitute the most important water resources available on the island. Dur- ing summer 2001, the intense water utilization of Lake Arancio reservoir reduced the water level signifi- cantly, which coincided with the formation of intense blooms formed by the microcystin (MC)-producing cyanobacterium Microcystis aeruginosa. During summer 2003, Lake Arancio was continuously filled and the vertical stratification of the water column was maintained resulting in five to sixfold lower cell numbers of M. aeruginosa. For both years, a significant relationship between MC net production and Microcysytis cell growth was observed, implying that Microcystis cell numbers can be used to infer MC concentrations in water. Unexpectedly, dense blooms of the MC-producing cyanobacterium Planktothrix rubescens occurred during winter 2005/2006 in the reservoirs Lake Pozzillo, Prizzi, Nicoletti, and Garcia but have not been reported earlier. In this season, MC concentrations higher than those recorded in summer were measured, implying that monitoring of Mediterranean drinking water reservoirs needs to be intensified during winter, a season usually considered to be less prone to the formation of cyanobacterial blooms.
TL;DR: The results of this study show that flavanoids, quercetin, silybin, and morin could reverse the hepatotoxic effects of MC‐LR in vivo.
Abstract: Toxic cyanobacteria (blue-green algae) water blooms have become a serious problem in several industrialized areas of the world. Microcystin-LR (MC-LR) is a cyanobacterial heptapeptide that represents acute and chronic hazards to animal and human health. Identification of suitable chemprotectants against microcystin is essential considering human health hazards. In the present study, we have evaluated the protective efficacy of three flavanoids namely quercetin (200 mg/kg), silybin (400 mg/kg), and morin (400 mg/kg)] pretreatment against microcystin toxicity (0.75 LD(50), 57.5 microg/kg) in mice. Various biochemical variables were measured to study the recovery profile of protected animals at 1- and 3-days post-toxin treatment. The serum alanine amino transferase (ALT) shows 17-fold increase in MC-LR treated animals compared with control group at 1 day. The silybin and quercetin group showed a decrease in level of ALT compared with MC-LR group but still higher than control group. No significant protection was observed with aspartate aminotransaminase (AST) and lactate dehydrogenase (LDH) levels in flavanoid-treated groups at 1-day post-treatment. But at 3 days, the serum levels of AST and ALT were normalized to control values, but the serum LDH levels were still significantly higher than the control group. No significant changes were observed in glutathione peroxidase and reduced glutathione levels at both 1- and 3-day postexposure. The catalase activity shows a significant decrease in quercetin-treated animals at 3-day postexposure. The protein phosphatase was significantly inhibited in MC-LR group compared to control. The silybin pretreated group showed recovery after 1 day. At 3 days, the PPAse activity was reversed to control values in all the flavanoid-treated groups. Immunoblotting analysis showed microcystin-PPAse adduct in liver tissues of toxin-treated as well as flavanoid-treated mice even after 3 days. The results of this study show that flavanoids, quercetin, silybin, and morin could reverse the hepatotoxic effects of MC-LR in vivo.
TL;DR: It is suggested that hyperthyroidism can cause a change in the expression level of PPAR‐r in testes, and may increase the levels of oxidative damage induced by the metabolic activation of DBP.
Abstract: This study compared the effects of di(n-butyl) phthalate (DBP) on the oxidative damage and antioxidant enzymes activity in testes of hyperthyroid rats. Hyperthyroidism was induced in pubertal male rats by intraperitoneal injection of triiodothyronine (T3, 10 microg/kg body weight) for 30 days. An oral dose of DBP (750 mg/kg) was administered simultaneously to normal or hyperthyroid (T3) rats over a 30-day period. No changes in body weight were observed in the hyperthyroid groups (T3, T3 + DBP) compared with controls. There were significantly higher serum T3 levels observed in the hyperthyroid rats than in the control, but the serum thyroid stimulating hormone levels were markedly lower in the hyperthyroid rats. DBP significantly decreased the weight of the testes in the normal (DBP) and hyperthyroid (T3 + DBP) groups. The serum testosterone concentrations were significantly lower in only DBP group. DBP significantly increased the 8-hydroxy-2-deoxyguanosine (8-OHdG) level in the testes, whereas the DBP-induced 8-OHdG levels were slightly higher in T3 + DBP group. Superoxide dismutase and glutathione peroxidase activities were significantly higher in the testes of the DBP or T3 + DBP groups. Catalase (CAT) activity was significantly higher in the DBP treatment group, but the T3 + DBP group showed slightly lower DBP-induced CAT activity. The testicular expression of thyroid hormone receptor alpha-1 (TRalpha-1) was significantly higher in the DBP groups, and androgen receptor (AR) expression was not detected in the DBP treatment group. In addition, DBP significantly increased the peroxisome proliferator-activated receptor-r (PPAR-r) levels in the testis. These results suggest that hyperthyroidism can cause a change in the expression level of PPAR-r in testes, and may increase the levels of oxidative damage induced by the metabolic activation of DBP.
TL;DR: The accumulation of nodularin (NOD), a cyanobacterial pentapeptide hepatotoxin, in sediments, blue mussels, and flounders from the Gulf of Gdańsk was studied by enzyme‐linked immunosorbent assay (ELISA) and the presence of NOD in sediment, mussel, and fish samples was confirmed.
Abstract: In the Gulf of Gdansk, as in other parts of the Baltic Sea, toxic blooms of Nodularia spumigena are an annual phenomenon. In the present work, the accumulation of nodularin (NOD), a cyanobacterial pentapeptide hepatotoxin, in sediments, blue mussels, and flounders from the Gulf of Gdansk was studied by enzyme-linked immunosorbent assay (ELISA). In the surface layers of the sediments NOD concentration ranged from 2.3 ng/g dry weight (dw) several months after cyanobacterial bloom to 75 ng/g dw during the bloom. The highest toxin content in mussels was 139 ng/g dw. In two sampling stations situated in the coastal waters of the Gulf of Gdansk the concentrations of NOD in sediments and mussels were significantly lower than those measured in the Gulf of Finland. In sediments and mussels collected in the Gulf of Gdansk, the toxin was also detected in March when N. spumigena did not occur. In flounder, NOD accumulated in the liver (489 ng/g dw), guts (21 ng/g dw), and gonads (21 ng/g dw). Hybride quadrupole-time-of-flight liquid chromatography/mass spectrometry/mass spectrometry (TOF-LC/MS/MS) confirmed the presence of NOD in sediment, mussel, and fish samples. Additionally, other NOD analogues, ([DMAdda3]NOD and [dhb5]NOD), were detected in sediments and mussel tissue. No NOD conjugates with reduced glutathione or cysteine were found in fish and mussels. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 101–111, 2007.
TL;DR: In amphibians, the CA appears to be a sensitive and suitable method for detecting genotoxicity such as that caused by Cd.
Abstract: The toxic and genotoxic potential of Cadmium (CdCl2) were evaluated by the micronucleus test (MNT) and comet assay (CA) using amphibian larvae (Xenopus laevis and Pleurodeles waltl). Acute toxicity results showed that Cd is toxic to Xenopus larvae exposed from 2 to 50 mg/L and to Pleurodeles from 5 to 50 mg/L, depending on the nature of the water (reconstituted water containing mineral salts or mineral water MW (Volvic 1 )). The MNT results obtained in MW showed that Cd (2 mg/L) is genotoxic to Xenopus, whereas it was not genotoxic to Pleurodeles at all concentrations tested. The CA established that the genotoxicity of Cd to Xenopus and Pleurodeles larvae depends on the concentration, the expo- sure times, and the comet parameters (Tail DNA, ETM, OTM, and TL). The CA and MNT results were compared for their ability to detect genotoxic effects, considering the concentrations of Cd applied and the exposure time. The CA showed Cd to be genotoxic from the first day of exposure. In amphibians, the CA appears to be a sensitive and suitable method for detecting genotoxicity such as that caused by Cd.
TL;DR: Algae grown in standard culture media are generally no more sensitive to metals than algae grown in a metal‐enriched medium, which supports the continued use of current laboratory bioassays with microalgae, as part of a suite of tests for assessing metal bioavailability, for use in ecological risk assessments and for providing data for the derivation of water quality guidelines.
Abstract: Current toxicity tests with microalgae are often criticized as being overly sensitive to metals because algae are cultured in metal-deficient media. If such bioassays overestimate copper toxicity in surface waters, the relevance of water quality guidelines derived from these tests is questionable. In this study, the effect of acclimation to copper at environmentally relevant concentrations, on the sensitivity of the marine diatom Nitzschia closterium and the freshwater green alga Chlorella sp. to copper and zinc was examined. N. closterium was acclimated in culture medium containing 5 or 25 μg Cu L−1 for 200 days, while Chlorella sp. was acclimated in medium containing 2 μg Cu L−1 for 100 days. Changes in algal growth rates and copper and zinc tolerance were monitored using standard growth inhibition toxicity tests in minimal medium over 72 h. Neither of the two acclimated N. closterium cultures had increased zinc or copper tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. Similarly, no changes in copper tolerance or control growth rates were observed for the acclimated Chlorella sp. culture. This was supported by measurements of intracellular and extracellular copper which confirmed that there were no differences in copper accumulation in either acclimated or nonacclimated algae. These results suggest that these algae grown in standard culture media are generally no more sensitive than algae grown in a metal-enriched medium. This supports the continued use of current laboratory bioassays with microalgae, as part of a suite of tests for assessing metal bioavailability, for use in ecological risk assessments and for providing data for the derivation of water quality guidelines. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 234–244, 2007.
TL;DR: The compounds producing hydroxyl radical species seems to be more promising to treat cyanobacterial blooms than the compounds producing the singlet oxygen.
Abstract: This study explores the use of photosensitizers and reactive oxygen species (ROS) to limit growth of cyanobacteria. We chose 12 phthalocyanines, tetraphenol porphyrine, and methylene blue as compounds producing singlet oxygen. Hydrogen peroxide was chosen as another source of ROS. These compounds were tested using algal toxicity tests in microplates on three cultures of green algae (Pseudokirchneriella subcapitata, Scenedesmus quadricauda, and Chlorella kessleri) and on three cultures of cyanobacteria (Synechococcus nidulans, Microcystis incerta, and Anabaena sp.). Results indicate that photosensitizers and singlet oxygen could be highly toxic for some selected phytoplankton species. Green alga Scenedesmus quadricauda was highly sensitive (EC50 = 0.07 mg/L) to compounds producing singlet oxygen, although it was not sensitive to hydrogen peroxide, which was about 10 times more toxic for cyanobacteria. We conclude that the compounds producing hydroxyl radical species seems to be more promising to treat cyanobacterial blooms than the compounds producing the singlet oxygen.
TL;DR: Serum concentrations of free microcystins were consistently lower than MMPB quantification of total microCystins: free micro Cystins as measured by ELISA were only 8–51% of totalMicrocystin concentrations as detected by the GC/MS method, while after intravenous exposure episodes, they found evidence of microcyStins in human serum in free and protein‐bound forms, though the nature of the protein‐ bound forms is uncertain.
Abstract: Microcystins are among the most commonly detected toxins associated with cyanobacteria blooms worldwide. Two episodes of intravenous microcystin exposures occurred among kidney dialysis patients during 1996 and 2001. Analysis of serum samples collected during these episodes suggests that microcystins are detectable as free and bound forms in human serum. Our goal was to characterize the biochemical evidence for human exposure to microcystins, to identify uncertainties associated with interpretation of these observed results, and to identify research needs. We analyzed serum samples using enzyme-linked immunosorbent assay (ELISA) methods to detect free microcystins, and gas chromatography/mass spectrometry (GC/MS) to detect 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB). MMPB is derived from both free and protein-bound microcystins by chemical oxidation, and it appears to represent total microcystins present in serum. We found evidence of free microcystins in patient serum for more than 50 days after the last documented exposure. Serum concentrations of free microcystins were consistently lower than MMPB quantification of total microcystins: free microcystins as measured by ELISA were only 8-51% of total microcystin concentrations as detected by the GC/MS method. After intravenous exposure episodes, we found evidence of microcystins in human serum in free and protein-bound forms, though the nature of the protein-bound forms is uncertain. Free microcystins appear to be a small but variable subset of total microcystins present in human serum. Research is needed to elucidate the human toxicokinetics of microcystins, in part to determine how observed serum concentrations can be used to estimate previous microcystin exposure.
TL;DR: This finding suggests that first of all an algicidal effect of phenols was probably the reason of the cyanobacterial biomass decreasing, and the mechanism of the growth inhibition could involve both the inhibition of the photosynthetic system and the alkaline phosphatase activity.
Abstract: Plant-producing phenols could strongly inhibit the growth of toxic cyanobacteria genera, but the ecological consequences of this action are still unknown. In this work, the activity of selected phenols in relation to the strain Microcystis aeruginosa was investigated. We have found that the mechanism of the growth inhibition could involve both the inhibition of the photosynthetic system and the alkaline phosphatase activity. The excretion of a high amount of microcystin-LR to the environment was observed as a final result of the application of phenols to the cyanobacterial culture. This finding suggests that first of all an algicidal effect of phenols was probably the reason of the cyanobacterial biomass decreasing.
TL;DR: The transmission electron microscopic analysis revealed that the 7 day exposure group had more severe effect in tissue alterations than the 24 h exposure group, and tissue regeneration was also observed in the 48 h recovery group.
Abstract: The present study investigated the accumulation of copper in various tissues and ultrastructural alterations in butterfish, Poronotus triacanthus. In acute toxicity test, butterfish were exposed to 250 μg/L copper for 24 h. In subacute toxicity test, fish were exposed to 25 μg/L copper for 7 days and then returned to normal water for 48 h. The levels of copper accumulation in the tissues were determined by using an atomic absorption spectrometer. After the 7 day exposure, the highest level of copper was found in the liver, followed by kidney, gills, and muscle tissues (3.64, 0.62, 0.59, and 0.34 μg/L, respectively). The recovery group has shown some reduction in copper level in these tissues when compared with those of the 7 day exposure group (3.09, 0.34, 0.30, and 0.27 μg/L, respectively). In gills, the major changes such as filament cell proliferation, increase in intercellular spaces, epithelial lifting, and thickening of the filament and lamellar epithelium were observed. In liver, the major changes such as swollen mitochondria, fragmented in rough endoplasmic reticulum, increases in number and size of lysosomes and lipid droplets. Infiltration of leukocytes, increasing hepatocyte size with pyknotic nuclei, and presence of vacuoles were also observed. In kidney, the changes included alterations of the first proximal tubules, as well as vacuolization of the cytoplasm, proliferation of lysosomes and mitochondria, dilation of endoplasmic reticulum, and finally, cell necrosis. The transmission electron microscopic analysis revealed that the 7 day exposure group had more severe effect in tissue alterations than the 24 h exposure group. Tissue regeneration was also observed in the 48 h recovery group. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 92–100, 2007.
TL;DR: The photocytotoxicity of 16 polycyclic aromatic hydrocarbons (PAHs) on the priority pollutant list of the United States Environmental Protection Agency were tested in human skin HaCaT keratinocytes and correlates well with several of their excited state properties: light absorption, excited singlet‐ state energy, excited triplet‐state energy, and HOMO‐LUMO energy gap.
Abstract: The photocytotoxicity of 16 polycyclic aromatic hydrocarbons (PAHs) on the priority pollutant list of the United States Environmental Protection Agency (US EPA) were tested in human skin HaCaT keratinocytes. A selected PAH was mixed with HaCaT cells and irradiated with a solar simulator lamp for a dose equivalent to 5 min of outdoor sunlight and the cell viability was determined immediately and also after 24 h of incubation. For the cells without incubation after the treatments, it is found that all PAHs with three rings or less, except anthracene, are not photocytotoxic, while the four or five-ring PAHs (except chrysene), benz[a]anthracene, dibenzo[a,h]anthracene, benzo[ghi]perylene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, benzo[b]fluorenthene, fluorenthene, and pyrene, are photocytotoxic to the human skin HaCaT keratinocytes. If the cells were incubated for 24 h after the treatments, the photocytotoxic effect of the PAHs was greatly amplified in comparison to the nonincubated cells. For the 24 h incubated cells, all PAHs except naphthalene exhibit photocytotoxicity to some extent. Exposure to 5 μM of the 4- and 5-ring PAHs (except chrysene) and 3-ring anthracene more than 80% of the cells lose viability. The photocytotoxicity of the PAHs correlates well with several of their excited state properties: light absorption, excited singlet-state energy, excited triplet-state energy, and HOMO-LUMO energy gap. All the photocytotoxic PAHs absorb light at >300 nm, in the solar UVB and UVA region. There is a threshold for each of the three excited state descriptors of a photocytotoxic PAH: singlet energy <355 kJ/mol (corresponding to 337 nm light), triplet energy <230 kJ/mol (corresponding to 520 nm light), HOMO-LUMO gap <3.6 eV (corresponding to 344 nm light) obtained at the Density Functional Theory B3LYP/6-31G(d) level.
TL;DR: There is a good correlation between the exposure concentrations and •OH generation and a possible mechanism of oxidative stress induced by HC Orange No. 1 on fish.
Abstract: HC Orange No. 1 (CAS No. 54381-08-7, 2-nitro-4'-hydroxydiphenylamine) is used as a color additive in hair dyes. In this study, laboratory experiment was carried out to determine HC Orange No. 1 bioaccumulation and oxidative stress in the liver of freshwater fish, goldfish Carassius auratus. Fish were exposed to different concentrations (0.05, 0.1, 0.2, 0.5, and 1.0 mg/L) of HC Orange No. 1 for 10 days, with one group assigned as control. The accumulation of HC Orange No. 1 in liver increased with the exposure concentration (R(2) = 0.94). A secondary spin trapping technique was used followed by electron paramagnetic resonance (EPR) analysis to study the reactive oxygen species (ROS) production. On the basis of the hyperfine splitting constants and shape of the EPR spectrum, the ROS generated in fish liver after exposure was identified as hydroxyl radical (*OH). There is a good correlation between the exposure concentrations and *OH generation (R(2) = 0.92). The *OH signal intensity of the EPR spectrum showed a significant increase (P < 0.05) when the HC Orange No. 1 concentration was 1.0 mg/L, compared with that of the control. A good positive relationship (R(2) = 0.95) was found between the *OH formation and accumulation level of HC Orange No. 1 in liver. The changes of the activities of catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and contents of reduced glutathione (GSH) were also detected. These observations indicated a possible mechanism of oxidative stress induced by HC Orange No. 1 on fish.
TL;DR: The MolDarT assay is characterized and shown its applicability for effect screening of compounds and both atrazine and cyproconazol showed no effect on relative Vtg1 abundance.
Abstract: The MolDarT is a novel short-term assay for testing mechanism-based molecular effects in developing zebrafish embryos. The objective of this study was to evaluate the inducibility of vitellogenin1 mRNA (Vtg1) by the estrogenically active compounds 17β-Estradiol (E2), 17α-Ethinylestradiol (EE2), Nonylphenol (NP), Bisphenol A (BPA), Cyproconazol, and the suspected xeno-estrogen Atrazin in the MolDarT. Freshly fertilized zebrafish eggs were exposed semistatically for 120 h. Using reverse transcription real-time PCR, the relative abundance of Vtg1 was measured. For EE2 a dose-response relationship was established with EC50 = 60.7 ng/L (205 pM). Induction of Vtg1 was significant at concentrations of 84 pM EE2 (25 ng EE2/L) and above, 10 nM E2 (2.7 μg E2/L), 100 nM E2 (27 μg E2/L), 10 μM BPA (2280 μg BPA/L), and 15 μM BPA (3420 μg BPA/L). At NP concentrations of 0.75 μM (165 μg NP/L) and 1.5 μM (330 μg NP/L) Vtg1 was significantly down-regulated. Both atrazine and cyproconazol showed no effect on relative Vtg1 abundance. With this study we further characterize the MolDarT assay and show its applicability for effect screening of compounds. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 185–193, 2007.
TL;DR: An enzyme‐linked immunosorbent assay analysis was used to test for the presence of the hepatotoxin microcystin‐LR in G. echinulata collected from an oligotrophic lake in central New Hampshire, USA, and found that it contained MC‐LR at mean concentrations of 97.07 ± 7.78 (1 s.e.) ng MC‐ LR g−1 dry wt colonies.
Abstract: Gloeotrichia echinulata is a bloom-forming cyanobacterium that is common in eutrophic lakes, and less prevalent but increasing in oligotrophic lakes. We used an enzyme-linked immunosorbent assay analysis to test for the presence of the hepatotoxin microcystin-LR (MC-LR) in G. echinulata collected from an oligotrophic lake in central New Hampshire, USA. We found that G. echinulata contained MC-LR at mean concentrations of 97.07 +/- 7.78 (1 s.e.) ng MC-LR g(-1) dry wt colonies. This suggests that recent outbreaks of G. echinulata in oligotrophic lakes used as water sources throughout New England (USA) may pose a health concern. The toxicity of G. echinulata reported here suggests the need for future monitoring of microcystins in oligotrophic lakes.
TL;DR: The histopathological changes observed were aneurisms, hyperplasia, lifting, and vasodilation, which were among the most recognized responses to environmental stressors, namely heavy metals.
Abstract: The histopathological changes are among the most recognized responses to environmental stressors, namely heavy metals. Liza saliens were sampled, in the Portuguese Esmoriz-Paramos coastal lagoon to assess their gill histopathological response to Cu and Zn contaminated sediments. A lesion prevalence index, severity, and extension scores of each lesion, as well as an assessment value (severity x extension), were determined to evaluate the effect of environmental heavy metal exposure. The main histopathological changes observed were aneurisms, hyperplasia, lifting, and vasodilation. A high prevalence for each lesion (65-85%) was found, in addition to a high number of simultaneous lesions. Vasodilation and hyperplasia were the lesions that showed higher prevalence indexes. Lifting, followed by hyperplasia, were the lesions with highest assessment value. The prevalence of the number of the lesions found in L. saliens collected from the Esmoriz-Paramos lagoon was high when compared with mullet caught in the sea. A previous work revealed that fish collected in the lagoon showed elevated Cu and Zn levels in their gills, in a positive correlation with age. However, no positive correlation was observed between assessment value and gill metal levels.
TL;DR: Assessment of the association between infrasound exposure of 5 Hz at 130 dB and changes of cardiac ultrastructure and function in rats found changes of [Ca2+]i and SERCA2 play an important role in the secondary cardiac damage.
Abstract: Recent interest in adverse effects of infrasound on organisms arises from health concerns. We assessed the association between infrasound exposure of 5 Hz at 130 dB and changes of cardiac ultrastructure and function in rats. Thirty-two Sprague-Dawley rats were randomized into control, 1, 7, and 14 days groups for 2 h of infrasound once daily according to planned schedules. Changes of cardiac ultrastructure, hemodynamics indices, intracellular Ca(2+) concentrations ([Ca(2+)](i)), and sarcoplasmic reticulum Ca(2+)-ATPase 2 (SERCA2) were detected. Heart rates in 1 day group were significantly increased compared with control group and no significant changes in other groups. Left ventricular systolic pressures were significantly increased with time. Left ventricular diastolic end pressure and maximum rising rates of left ventricular pressure (+dl/dt) were significantly increased in 7 and 14 days groups and not changed in 1 day group, compared with control group. Maximum dropping rates of left ventricular pressure (-dl/dt) were significantly decreased in 7 and 14 days groups and not changed in 1 day group, compared with control group. In heart cells, there were several swelled mitochondria in 1 day group, more swelled mitochondria in 7 days group, platelet aggregation in the intercellular substance in 14 days group. [Ca(2+)](i) were significantly increased with time. There was a significant increase in SERCA2 in 1 day group, while a significant decrease in 7 and 14 days groups, compared with control group. Infrasound of 5 Hz at 130 dB can damage cardiac ultrastructure and function. Changes of [Ca(2+)](i) and SERCA2 play an important role in the secondary cardiac damage.
TL;DR: The influence of phosphate on the toxicity of uranium to Lemna gibba G3 was tested in semicontinuous culture with synthetic mine water developed as an analogue of surface water of two abandoned uranium mining and ore processing sites in Saxony, Germany, showing significant inhibition of specific growth rates.
Abstract: The influence of phosphate on the toxicity of uranium to Lemna gibba G3 was tested in semicontinuous culture with synthetic mine water developed as an analogue of surface water of two abandoned uranium mining and ore processing sites in Saxony, Germany. Six concentrations of uranium were investigated under five different supply regimes of PO(4) (3-) at constant pH (7.0 +/- 0.5) and alkalinity (7.0 +/- 1.6 mg L(-1) total CO(3) (2-)). The results showed significant inhibition of specific growth rates in cultures exposed to the highest uranium concentrations (3500 and 7000 microg U L(-1)) at lowest PO(4) (3-) supply of 0.01 mg L(-1). An increase of phosphate concentration from 0.01 to 8.0 mg L(-1) resulted in an increase of EC(50) from 0.9 +/- 0.2 to 7.4 +/- 1.9 mg L(-1) (significant with Student's t test, P > 0.05). The accumulation of uranium in L. gibba increased exponentially with the increase in uranium concentration in cultures with 0.01 and 0.14 mg PO(4) (3-) L(-1). Accumulation also increased significantly when PO(4) (3-) supply was increased from 0.14 to 1.36 mg PO(4) (3-) L(-1) for all uranium concentrations. However, as the supply of PO(4) (3-) gradually increased from 1.36 to 8.0 mg PO(4) (3-) L(-1), uranium bioaccumulation increased slightly but insignificantly before leveling off. Uranium speciation modeling with PhreeqC geochemical code predicted increases in the proportions of uranyl phosphate species when PO(4) (3-) concentrations increase in the media. Most of these uranyl phosphate species have a high probability of precipitation [saturation indices (SI) > 0.93]. Therefore, the alleviation of uranium toxicity to L. gibba with phosphates is due to interactions among components of the media, mainly uranyl and phosphate which results in precipitation. Consequently, bioavailable fractions of uranium to L. gibba are reduced. This might explain lack of consistent EC(50) values for uranium to most aquatic organisms.
TL;DR: These are the first reported survival and developmental data for an aquatic insect exposed to MeHg and Se‐MeHg mixtures.
Abstract: Pollutants rarely occur alone in the natural environment, and few studies have focused on the potential interactions between metals or metalloids. In this study an aquatic insect, the southern house mos- quito (Culex quinquefasciatus: Diptera), was used to test the individual and joint effects of dissolved sodium selenate (Se) and methyl mercury chloride (MeHg). We conducted ovipositional preference tests and 14-day chronic toxicity studies to determine lethal and sublethal responses of C. quinquefasciatus to a range of Se and MeHg concentrations and mixtures. No evidence was found for female ovipositional preference in field trials using artificial ponds. Larvae were more sensitive to MeHg than Se, with LC50 values of 30 � g/L (CI ¼ 28-31 � g/L) and 11 mg/L (CI ¼ 10-12 mg/L) respectively. In addition, larval survival was significantly reduced at concentrations as low as 25 � g/L of MeHg and 8 mg/L of Se. A synergistic interaction was observed in the toxicity of the Se-MeHg mixtures to C. quinquefasciatus larvae. Larval mosquito survival was significantly reduced at 7.5 � g/L MeHg þ 2.75 mg/L Se and an LC50 value of 9 � g/L MeHg þ 3.4 mg/L Se was deter- mined for a fixed ratio mixture. The rate of growth of the larvae was analyzed using a Growth Index that pro- vided a sensitive measure of the developmental effects of toxicant exposure. Sodium selenate at concentra- tions as low as 2 mg/L caused a significant decrease in growth between larvae in treatment versus control solutions after only 4 days. Similarly, MeHg at concentrations as low as 25 � g/L and a Se-MeHg mixture of 3 � g/L MeHg plus 1.1 mg/L Se caused significant growth reductions after only 2 and 3 days, respectively. These are the first reported survival and developmental data for an aquatic insect exposed to MeHg and
TL;DR: In this paper, male mice were exposed to OP at two different developmental stages, and the expression of steroidogenic enzymes and testosterone production were evaluated Juvenile (15-day-old) and adult (8-week-old)-male mice were injected with 2, 20, or 200 mg/kg of OP or 02 microg/ kg of estradiol valerate for 5 days Testosterone concentration was measured by radioimmunoassay and the expressions of the testicular genes were determined by RT-PCR analysis and immunohistochemistry
Abstract: 4-tert-octylphenol (OP) is known to disrupt testicular development and reduce male fertility In the present study, male mice were exposed to OP at two different developmental stages, and the expression of steroidogenic enzymes and testosterone production were evaluated Juvenile (15-day-old) and adult (8-week-old) male mice were injected with 2, 20, or 200 mg/kg of OP or 02 microg/kg of estradiol valerate for 5 days Testosterone concentration was measured by radioimmunoassay and the expressions of the testicular genes were determined by RT-PCR analysis and immunohistochemistry In the animals exposed with 20 mg/kg of OP during juvenile stage, histochemical analysis of the testis showed that number of pyknotic germ cells inside the tubule was increased, while the number of oil red O positive Leydig cells was decreased Moreover, the lumen formation was remarkably delayed A reduced serum testosterone concentration and down-regulated expressions of the mRNAs for steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (P450scc), and 17alpha-hydroxylase/C(17-20) lyase (P450(17alpha)) were also observed after juvenile exposure to OP Immunohistochemical staining for P450scc was mainly detected in interstitial Leydig cells, and a slightly reduced expression of P450scc protein was observed in the testis exposed to 20 mg/kg of OP during juvenile stage The present study demonstrates that juvenile exposure to OP inhibits steroidogenesis by decreasing the expressions of steroidogenic enzymes in the testis Diminished lipid content in Leydig cells and reduced transcriptional expression of the cholesterol transport gene, StAR, also support altered cholesterol metabolism and/or transport as a potential mechanism for the decreased testosterone production following exposure to OP Altogether, the alteration of steroidogenesis by exposure to OP may adversely affect the normal development of the testis and spermatogenesis