Susceptibility of the freshwater pulmonate snail Lymnea luteola L. to copper oxide nanoparticle

Copper oxide nanoparticles (CuONP) are among the most widely used engineered nanoparticles and thus likely to permate the environment predominantly in sediments. The present study was designed to examine the adverse effects of CuONP in freshwater snail Lymnea luteola L. (L. luteola) exposed for 5 days. Induction of oxidative stress in digestive gland was evidenced by a decrease in reduced glutathione (GSH) levels, and activities of glutathione peroxidase (GPx) and glutathione-S-transferase (GST) whereas lipid peroxidation levels were increased at CuONP 7 or 21 µg/L. Superoxide dismutase activity was numerically higher at lower concentration of CuONP at 1 day but significantly decreased at 5 days. Catalase activity was reduced at 2 days but elevated at lower concentration of CuONP at 5 days. DNA impairment was noted in L. luteola based upon comet assay findings and expressed in terms of % tail DNA and olive tail moment. Results indicate that interaction of CuONP with snail produces toxicity, which is mediated by oxidative stress.     

Evaluation of environmental stress by comet assay on freshwater snail Lymnea luteola L. exposed to titanium dioxide nanoparticles

The use of aquatic organisms to monitor for contamination is well-established. Therefore, this study was designed to assess the adverse effects of titanium dioxide nanoparticles (TiO₂NP) in freshwater snail Lymnea luteola L. (L. luteola). For TiO₂NPs ecotoxicity tests, snails were exposed for seven days. A dose and time-response relationship was observed for TiO₂NP-induced genotoxicity. Induction of oxidative stress in digestive gland was observed by a decrease in glutathione and gluthathions-S-transferase levels accompanied by elevated malondialdehyde levels at TiO₂NP (9 and 28 µg/mL). Superoxide dismutase activities were markedly reduced at TiO₂NP (9 and 28 µg/mL) at days 1 and 3, but not at day 7. Catalase activities were decreased at days 1 and 3 but increased at higher concentration of TiO₂NP at day 7. DNA fragmentation occurring in L. luteola due to ecotoxic impact TiO₂NP was further substantiated by alkaline single-cell gel electrophoresis assay and expressed in terms of percent tail DNA and olive tail moment. The results indicate that the interaction of these TiO₂NP with snail influences the toxicity, which is mediated by oxidative stress in a dose- and time-dependent manner. The measurement of DNA integrity in L. luteola thus provides an early warning signal of contamination of the aquatic ecosystem by TiO₂NP. Data suggest the freshwater snail L. luteola is a potential biomonitor organism.     

Effects of benzo(k)fluoranthene,a polycyclic aromatic hydrocarbon on DNA damage,lipid peroxidation and oxidative stress in marine gastropod Morula granulata

Benzo(k)fluoranthene [B(k)F] is one of the widespread priority pollutants of polycyclic aromatic hydrocarbons that has been scarcely studied for exposure assessment. With studies reporting a high amount B(k)F in sediments and water samples around the world, it has become vital to study its effects on aquatic organisms. In this connection, this study is conducted to study the effect of different concentrations of B(k)F (1, 10, 25 and 50?µg/L) in marine gastropod Morula granulata exposed in vivo for 96?h. A concentration-dependent increase in percentage tail DNA (TDNA) as measured by comet assay was observed in snails exposed to B(k)F. Exposure concentrations above 1?µg/L B(k)F showed significant increase in superoxide dismutase (SOD) activity and lipid peroxidation value in snails. After 96?h, SOD activity was found to be doubled for 50?µg/L B(k)F in comparison to control. A significant increase in catalase and glutathione S-transferase activity was observed at all exposure conditions at the end of the exposure time. Our study showed that B(k)F induces oxidative stress in snails which further lead to genotoxic damage. To our knowledge, this is the first study on oxidative stress and genotoxic damage in gastropods exposed to B(k)F.     

Oxidative stress in the freshwater cyprinid crucian carp (Carassius carassius L.) upon chronic exposure to endosulfan

Oxidative stress and antioxidant responses of crucian carp, upon chronic exposure to endosulfan, were evaluated in vivo. The lethal concentration (LC_50–96?h) was 70 μg L^?1; on its basis, the fish were exposed to endosulfan at 20, 35, and 50 μg L^?1 and autopsy was done on days 1, 2, 3, 4, 7, 14, 21, 28, and 35. Lipid peroxidation was induced in a concentration-dependent manner, being highest at 50 μg L^?1 (3/4 LC_{50–96 h}, sub-lethal concentration-I, SL-I) on day 4 (720% versus control), followed in its extent (490%) at 30 μg L^?1 (1/2 LC_{50–96 h}, sub-lethal concentration-II, SL-II) on day 7 and lowest (260%) at 10 μg L^?1 (1/4 LC_{50–96 h}, sub-lethal concentration-III, SL-III) on day 14. Glutathione showed a concentration- and time-dependent elevation in the initial phase, with highest level on day 4 (180%) at SL-I, but showed significant reduction in all test concentrations from day 21 of post-exposure. Superoxide dismutase was decreased significantly throughout the study, with highest reduction (63%) on day 4 at SL-I; catalase increased in all test concentrations up to day 14 but showed a significant decrease from the day 28 of post-exposure. The potential role of these parameters as indicators of pesticide pollution in aquatic systems is discussed.     

三氯生和三氯卡班对人体肝细胞DNA损伤的研究

三氯生（TCS）和三氯卡班（TCC）作为优良的抗菌和消毒剂,在药物和个人护理用品中广泛使用。近几年来,TCS和TCC在各种环境介质和生物体中被频繁检出,并引起国内外环境科学工作者的重点关注。目前,有关TCS和TCC对水生生物的毒性研究已有大量的报道,其对人体健康危害的报道仍较少。为了评估TCS和TCC对人体的遗传毒性,利用彗星实验研究两种污染物对正常人肝细胞（L02）DNA的损伤效应。结果发现：三氯生和三氯卡班皆能引起人体肝细胞的DNA损伤,并呈现显著的剂量-效应关系和时间效应关系。相比于TCS而言,L02细胞对TCC更为敏感,在低暴露剂量（2.38μmol.L-1）下就可以引起DNA断裂损伤。该结果有助于进一步揭示TCS和TCC对人体毒害的机制,更全面的评估两种污染物对人体健康的风险。     

Genotoxicity biomarkers in the amphipod Gammarus elvirae exposed in vivo to mercury and lead,and basal levels of DNA damage in two cell types

The present work deals with the application of genotoxicity biomarkers by means of the Comet assay in haemocytes and spermatozoa of the crustacean Gammarus elvirae exposed in vivo to heavy metals. Furthermore, a basal levels (BLs) study of DNA damage in the two cell types considered for two different gammarids species, G. elvirae and Echinogammarus veneris, was carried out. It is important to identify factors that influence the outcome of the assay in order to obtain reliable and reproducible results usable for risk assessment purposes. Our results highlight that the Italian legal limits for Hg and Pb, respectively, 0.5 and 50?µg/L, are inadequate for establishing safety thresholds in the aquatic environment. Furthermore, the freshwater invertebrate G. elvirae, used for the first time to measure the effect of genotoxicants, is a good candidate for evaluating the genotoxicity damage induced by heavy metals. Our results concerning spermatozoa show excessively variable responses and high BLs.     

Lysosomal,genetic and chromosomal damage in haemocytes of the freshwater bivalve (Unio pictorum) exposed to polluted sediments from the River Cecina (Italy)

The response to chemical disturbance of an Italian river (Cecina River) characterised by high levels of trace metals was assessed in the sentinel species freshwater painter’s mussel (Unio pictorum). We exposed U. pictorum in the laboratory to metal, metalloid and other trace element polluted river sediments in order to evaluate genetic and cellular biomarkers. Bivalves exposed to sediments taken from all the impacted sites of the river basin exhibited a significant impairment at the DNA, chromosomal and lysosomal levels. The lysosomal membrane stability of circulating haemocytes, assessed by the Neutral Red Retention Time, was found to be higher in specimens from Lake Maggiore and Berignone, while exhibited a significant decrease in specimens exposed to Ponteginori sediments. An increase of DNA migration in specimens exposed to the two contaminated sites in comparison with controls was found. Moreover, higher micronucleated haemocytes frequencies were observed in bivalves exposed to sediments collected at Possera 1 site. This study suggested that biomarkers evaluating cellular impairment, genetic and chromosomal damages, are highly sensitive and suitably applied to laboratory experiments. The painter’s mussel was confirmed to be an appropriate sentinel species for quality assessment in metal-contaminated freshwater environments.     

Thimerosal in childhood vaccines contributes to accumulating mercury toxicity in the kidney

Mercury (Hg) is a hazardous chemical that accumulates in many cells and tissues, thereby producing toxicity. The kidney is a key target organ for Hg accumulation and toxicity. The contributing factors to Hg accumulation in humans include: (1) elemental and inorganic Hg exposure, often occurring by inhalation of Hg vapors; (2) exposure to methyl Hg (meHg), for example, through contaminated seafood; and (3) exposure to ethyl mercury (etHg) via thimerosal-containing vaccines. Systematic investigations on the toxic effects of etHg/thimerosal on the nervous system were carried out, and etHg/thimerosal emerged as a possible risk factor for autism and other neurodevelopmental disorders. There is, however, little known about the mechanisms and molecular interactions underlying toxicity of etHg/thimerosal in the kidney, which is the focus of the current review. Susceptible populations such as infants, pregnant women, and the elderly are exposed to etHg through thimerosal-containing vaccines, and in-depth study of the potential adverse effects on the kidney is needed. In general, toxicity occurring in association with different forms of Hg is related to: intracellular thiol metabolism and oxidative stress reactions; mitochondrial function; intracellular distribution and build-up of calcium; apoptosis; expression of stress proteins; and also interaction with the cytoskeleton. Available evidence for the etHg-induced toxicity in the kidney was examined, and the main mechanisms and molecular interactions of cytotoxicity of etHg/thimerosal exposure in kidney described. Such accumulating knowledge may help to indicate molecular pathways that, if modulated, may better handle Hg-mediated toxicity.     

Implications of oxidative stress in occupational exposure to lead on a cellular level

The aim of this study was to determine oxidative alterations leading to cellular dysfunctions in Pb-exposed subjects by evaluating damage to all major classes of biomolecules in the cell, lipid peroxidation, protein and DNA damage and determine relationships between parameters of Pb toxicity and specific biomarkers of oxidative damage.

Analysis was conducted of smelter workers with high blood Pb and urine aminolevulinic acid levels and slightly elevated values of coproporphyrin and erythrocyte protoporphyrin IX. Significant decreases of thiol groups and increases in carbonyl groups as protein degradation end products, and of nitrite were detected. Elevated rates of lipid peroxidation and rises in the activities of the antioxidant enzymes Cu–Zn superoxide dismutase and catalase were also observed. Both enzymes showed positive correlations with the blood lead levels and urine coproporphyrin, while thiol groups correlated negatively with the same indices. The genotoxic potential of lead was manifested through an increased number of DNA-damaged cells. Increased activities of serum lactate dehydrogenase isoenzymes indicated cellular damage in the lungs, kidneys, and liver. These lead-induced impairments should be taken into consideration in the assessment of Pb-related health hazards.     

Influence of hypothyroidism on oxidative stress,c-Fos expression,cell cycle,and apoptosis in rats testes

The molecular basis of male reproduction for cross-regulation between androgen and thyroid hormone axes is still rudimentary. This study aims to define a possible mechanism of hypothyroidism-induced reproductive influence with respect to sex hormone, mineral, sperm motility, oxidative stress, c-Fos expression, cell cycle, and apoptosis in rat testes. The Wistar rats were randomly divided into control group (NS) and hypothyroidism group [1 ml/100g BW/day, 0.1% propylthiouracil (PTU)] by intragastric gavage for 60 days. Blood samples were collected to measure the serum levels. The epididymis was excised to measure sperm motility and testes were excised to measure mineral, oxidative stress, c-Fos expression, cell cycle, and apoptosis. After 60 days, body weight, relative testes weight, triiodothyronine, and total thyroxine were all significantly decreased, whereas thyroid stimulating hormone was increased in the hypothyroidism group. A significant increase in sex hormone level of estradiol (E2) and significant decreases in testosterone (T) and T/E2 ratio were observed following PTU treatment. And sperm quality was also significantly changed. There were significant decreases in the contents of calcium (Ca²⁺) and zinc (Zn²⁺). On the other hand, malondialdehyde and hydrogen peroxide contents significantly increased, whereas the activity of superoxide dismutase, catalase and nitric oxide synthase and nitric oxide content significantly decreased in hypothyroid rats. The mRNA and protein expressions of c-Fos decreased significantly. The cell percentage in G0/G1 phase increased significantly, whereas decreased significantly in S and G2/M phases. Also, a significant increase in testicular cell apoptosis was observed in hypothyroid-treated rats. These results suggested that hypothyroidism could affect reproductive function in the form of changed sex hormone levels, sperm motility and testicular Ca²⁺ and Zn²⁺, and enhanced oxidative stress leading to c-Fos abnormal expression and increased apoptosis.     

Neurotoxicity and oxidative stress induced by permethrin in gills of the freshwater mussel Unio ravoisieri

Pyrethroids are contaminants found in the aquatic environment, and their toxicological effects on aquatic organisms have received extensive attention. However, the impact on freshwater bivalve of exposure to these chemicals is still largely unknown. Freshwater mussels Unio ravoisieri were exposed to two nominal permethrin (PM) concentrations C1?=?50?µg/L and C2?=?100?µg/L during 7 days. The measured concentrations of PM using gas chromatography (GC/ECD) in the treated aquariums were, respectively, 28.7–62.3?µg/L. Catalase (CAT), Glutathione-S-transferase (GST), and Acetylcholinesterase (AChE) activities, Glutatione (GSH) and Malondialdehyde (MDA) levels were determined in gills of U. ravoisieri. Significant increase in CAT activity by the lowest concentration and decrease by highest concentration were observed. Additionally, GST activity was increased in a concentration-dependent manner. However, statistically significant decrease in GSH levels (about 39%) was observed only at high concentration of this compound (100?µg/L). PM generated an increase in MDA levels reaching the highest value at the high concentration. AChE activity of mussel ranging from 51% inhibition at lowest concentration 50?µg/L to 89% inhibition at highest concentration 100?µg/L. The results indicated that oxidative stress and cell damage might be one of the main mechanisms of PM toxicity to freshwater mussels.     

Effects of subchronic exposure to carbofuran on antioxidant defence system and malondialdehyde levels in common carp (Cyprinus carpio L.)

The present study focused on the assessment of oxidative stress induction by pesticides such as carbamates which are widely used as insecticides and nematicides and contaminate aquatic ecosystems on certain biomarkers in liver of common carp (Cyprinus carpio L.). Biomarkers selected for stress monitoring were malondialdehyde (MDA), an index of lipid peroxidation, and antioxidant defence system enzymes, mainly catalase (CAT), glutathione reductase (GR), and glutathione-S-transferase (GST) activities in liver of fish exposed to 0, 10, 50, or 100?µg?L^?1 of carbofuran for 4, 15, or 30 days. Oxidative stress was found in liver of common carp exposed to carbofuran which was manifested by a decrease in CAT and GR activities after 4 and 30 days of exposure. An adaptive response was probably produced since at day 15 no modifications in the CAT activity and increased GR activity were observed. In addition, a decrease in MDA content with the highest concentration of carbofuran used was found after 30 days of exposure. However, no significant changes were found in GST activity showing a varied response. The results concerning oxidative and antioxidant profiles indicate that subchronic exposure to the insecticide carbofuran is capable of inducing oxidative stress in fish.     

Physiological responses of Cladophora glomerata to cyanotoxins: a potential new phytoremediation species for the Green Liver Systems

Due to increased pollution of potable water sources as a consequence of eutrophication and anthropogenic xenobiotics, sustainable water purification is an essential concern. Therefore, the Green Liver System, a natural, economic and sustainable water purification system employing the biotransformation capabilities of aquatic plants, was developed. To expand the capacities and applications of this system, new aquatic plants are continually evaluated for their potential to remediate various aquatic pollutants. In this study, the potential of Cladophora glomerata to internalize cyanotoxins, microcystins (MCs) and anatoxin-a, and consequently its ability to cope with the subsequent oxidative stress associated with toxin-uptake were investigated. C. glomerata was able to take up all three of the tested MC congeners as well as anatoxin-a, similarly to previous toxin internalizations reported for aquatic plants such as Ceratophyllum demersum, Myriophyllum spicatum and Hydrilla versiculata. The antioxidative stress defense of C. glomerata proved to efficiently endure the toxin-uptake with no adverse effects. Subsequently, the uptake potential of C. glomerata was investigated at lab-scale by exposure to the three MC congeners and anatoxin-a collectively. After a period of seven days, 95–97% of the MCs and 100% of anatoxin-a were removed from the exposure media. C. glomerata therefore, is a suitable candidate to be incorporated in future Green Liver Systems.     

狼尾草根系对阿特拉津长期胁迫的氧化应激响应

通过盆栽实验研究了抗性植物狼尾草根部丙二醛(MDA)、脯氨酸(Pro)、抗坏血酸(As A)含量及超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)等氧化应激生理指标对不同浓度阿特拉津长期(48 d)胁迫的响应规律。结果表明:当阿特拉津胁迫浓度分别高于20 mg·kg~(-1)和50 mg·kg~(-1)时,狼尾草根系的MDA与Pro含量较对照组显著升高(P0.05);随着阿特拉津胁迫浓度的增加,狼尾草根部SOD和GR活性呈先升高后降低的趋势,其中当阿特拉津胁迫浓度为20 mg·kg~(-1)时,SOD和GR活性达到最大值;供试植物根系中As A含量与阿特拉津胁迫浓度呈正相关。综上,中低浓度(≤20 mg·kg~(-1))阿特拉津处理没有对狼尾草的根系产生明显的氧化胁迫效应,狼尾草根系的上述抗氧化应激生理指标对于发挥阿特拉津抗性起着重要的作用。     

The plausibility of a role for mercury in the etiology of autism: a cellular perspective

Autism is defined by a behavioral set of stereotypic and repetitious behavioral patterns in combination with social and communication deficits. There is emerging evidence supporting the hypothesis that autism may result from a combination of genetic susceptibility and exposure to environmental toxins at critical moments in development. Mercury (Hg) is recognized as a ubiquitous environmental neurotoxin and there is mounting evidence linking it to neurodevelopmental disorders, including autism. Of course, the evidence is not derived from experimental trials with humans but rather from methods focusing on biomarkers of Hg damage, measurements of Hg exposure, epidemiological data, and animal studies. For ethical reasons, controlled Hg exposure in humans will never be conducted. Therefore, to properly evaluate the Hg-autism etiological hypothesis, it is essential to first establish the biological plausibility of the hypothesis. This review examines the plausibility of Hg as the primary etiological agent driving the cellular mechanisms by which Hg-induced neurotoxicity may result in the physiological attributes of autism. Key areas of focus include: (1) route and cellular mechanisms of Hg exposure in autism; (2) current research and examples of possible genetic variables that are linked to both Hg sensitivity and autism; (3) the role Hg may play as an environmental toxin fueling the oxidative stress found in autism; (4) role of mitochondrial dysfunction; and (5) possible role of Hg in abnormal neuroexcitory and excitotoxity that may play a role in the immune dysregulation found in autism. Future research directions that would assist in addressing the gaps in our knowledge are proposed.     

The role of root organic acids in the tolerance of Festuca rubra to zinc,lead and cadmium

Abstract

Festuca rubra L. plants are pseudometallophytes colonizing abandoned Pb/Zn mine areas, successfully employed in phytostabilization. To study the contribution of low-molecular weight organic acids to metal tolerance, F. rubra plants were grown for three months in hydroponics with Cd (1.8, 18 and 36 µmol?L^?1), Pb (50, 250 and 500?µmol?L^?1) and Zn (0.3, 3 and 6?mmol?L^?1), separately, and in ternary combination (18?µmol?L^?1 Cd + 250?µmol?L^?1 Pb + 0.3?mmol?L^?1 Zn). The roots retained most of the metals but their distribution from shoot to root was altered when the plants were treated with the ternary combination. The main organic acids in roots were citrate and malate. At the lowest concentrations, the metals caused small reductions in biomass, had no effects on photosynthetic pigments nor on malondialdehyde, but led to increases in root organic acids. At higher concentrations, phytotoxic responses were observed, associated with a decline of citrate and malate in the roots.     

Lead and copper in the sclerotium of the mushroom Pleurotus tuber-regium (Osu): assessment of contribution to dietary intake in southeastern Nigeria

The concentrations of lead and copper in sclerotium of the mushroom Pleurotus tuber-regium widely consumed in Southeastern Nigeria were determined. The specimens purchased from different markets were mineralized with H₂SO₄ and H₂O₂ and analyzed using flame atomic absorption spectrophotometer. The concentrations of Pb ranged from 0.2?±?0.1?mg?kg^?1 to 0.8?±?0.5?mg?kg^?1 with approximately 91% of the results being below 1?mg?kg^?1. The concentrations of Cu ranged from 0.5?±?0.2?mg?kg^?1 to 1.2?±?0.6?mg?kg^?1 with 78% of the results below 1?mg?kg^?1. The results were compared with the literature and levels set by regulatory authorities, with the conclusion that the consumption of sclerotium does not pose a toxicological risk. The low Pb content of the studied products would contribute to only about 1% of the provisional tolerable weekly intake of Pb. The Cu contents would contribute to nutritional intake of the metal in the general population. It is recommended that the outer layers of the sclerotia be properly scrapped before use to reduce metal contamination from exogenous sources.     

Antipredator responses of California ground squirrels to rattlesnakes and rattling sounds: the roles of sex,reproductive parity,and offspring age in assessment and decision-making rules

California ground squirrels (Spermophilus beecheyi) and northern Pacific rattlesnakes (Crotalus viridus oreganus) have an adversarial relationship. Adults are partially protected by venom resistance and harass rattlesnakes in part to defend their more vulnerable offspring. Larger, warmer snakes are more dangerous than smaller colder snakes, and in escalated conflict squirrels could benefit from risk assessment strategies. Rattlesnakes often rattle at harassing squirrels and rattling sounds produce cues related to body size and temperature. In study 1 we played back rattling sounds from snakes that varied in dangerousness and evaluated the roles of sex and parity in squirrel risk assessment strategies. In general, squirrels tail flagged and stood bipedally more, and were slower to reapproach the playback speaker following playbacks of rattling sounds from more dangerous snakes. In comparison with males and nonmothers, mothers were most responsive to rattling sounds and more sensitive to variation in snake dangerousness. Mothers tail flagged more than males and nonmothers, and this behavior tracked variation in snake dangerousness most closely, perhaps reflecting the effects of snake size and temperature on pup vulnerability. These findings suggest that many aspects of squirrel antisnake behavior are governed by their effects on descendant kin. In study 2 we tested the effects of offspring age on mothers responses to live rattlesnakes and rattling sounds. According to the offspring value hypothesis, mothers should take more risks in defense of older offspring because they are more likely to survive to reproductive age. By contrast, under the offspring vulnerability hypothesis, older offspring are less vulnerable to predators and thus mothers should take fewer risks. Risk-taking, as measured by behaviors that bring the squirrel close to the snakes strike range, was either unaffected by or negatively correlated with offspring age. Thus, our findings suggest that whereas offspring value is unimportant in squirrel antisnake behavior, offspring vulnerability may affect maternal defense. We suggest that offspring vulnerability in mammals, in comparison with birds, may play a larger role in parental defense against predators.Communicated by P.A. BednekoffAn erratum to this article can be found at