Reduction and methylation of mercury in the terrestrial isopod Porcellio scaber (Crustacea) and its environment

Reduction and methylation of inorganic mercury in Porcellio scaber (Isopoda, Crustacea) and its environment were studied, using a purpose-built experimental setup where Hg cycling was followed using 203Hg2+ tracer in experiments without and with isopods. In experiment without isopods, daily reduction of 203Hg2+ to 203Hg0 under sterile and nonsterile conditions was measured for three weeks to assess the contribution of bacteria to this process. In experiments with isopods, daily release of 203Hg0 was measured for two weeks. Total mercury (T203Hg) and monomethylmercury (Me203Hg) in whole animals, gut, digestive glands (hepatopancreas), food (hazelnut leaves), and feces were measured to obtain the assimilation and distribution of mercury in the animals, to investigate the origin and fate of Me203Hg, and, finally, to assess the mass balance of mercury in the experimental system. Experiment without isopods showed the important role of bacteria in reduction of 203Hg2+ to 203Hg0, especially in the first day of the experiment. Experiments with isopods showed that formation of 203Hg0 depended on the 203Hg2+ concentration in the food. The contribution of the isopod's digestive flora in reduction of 203Hg2+ to 203Hg0 was negligible. Approximately 3% of T203Hg and 2% of Me203Hg consumed was assimilated by the animals. Methylation of 203Hg2+ occurred already in the leaves before they were consumed by the isopods. Assimilation of Me203Hg from the food surprisingly was low. Also, a loss of Me203Hg was noticed when comparing assimilated and excreted Me203Hg versus consumed Me203Hg. This may be explained by the assumption that demethylation of MeHg prevailed over methylation of Hg2+ in the animal's digestive system, leading to excretion of ingested mercury as Hg2+.     

Physiological effect of anatase TiO(2) nanoparticles on Lemna minor

Manufactured metal oxide nanoparticles (NPs) are being used on a large scale, and these particles will inevitably reach a body of water through wastewater and urban runoff. The ecotoxicological study of these NPs on hydrophyte is limited at present. Lemna minor was exposed to media with different concentrations of titanium dioxide (TiO(2) ) NPs or bulk TiO(2) for 7 d. The changes in plant growth, chlorophyll, antioxidant defense enzymes (peroxidase [POD], catalase [CAT], and superoxide dismutase [SOD] activities), and malondialdehyde (MDA) content were measured in the present study. The particle size of TiO(2) NPs and the zeta potential of TiO(2) NPs and of bulk TiO(2) in the culture media were also analyzed to complementally study the toxicity of these materials on duckweed. The results showed that the effect of TiO(2) NPs on plant growth was more obvious than bulk TiO(2.) Titanium dioxide NPs stimulated plant growth in low concentrations, but inhibited plant growth at high concentrations. The POD, SOD, and CAT activity of Lemna minor increased when TiO(2) NP concentration was lower than 200?mg/L to eliminate accumulated reactive oxygen species in plant cells. The SOD activity decreased when the TiO(2) NP concentration was higher than 200?mg/L, and the plant cell membrane encountered serious damage from 500?mg/L TiO(2) NP concentration in the culture media. Environ. Toxicol. Chem. 2012; 31: 2147-2152. ? 2012 SETAC.     

Uptake and elimination of benzo[a]pyrene in the terrestrial isopod Porcellio scaber

In isopods from contaminated sites relatively low levels of high molecular weight polycyclic aromatic hydrocarbons (PAHs) have been observed, which may be caused by either a low bioavailability or a high elimination rate. To shed light on this, the uptake and elimination rates of benzo[a]pyrene were estimated for the isopod Porcellio scaber. The isopod was fed contaminated food (100 g benzo[a]pyrene/g dwt) for seven weeks followed by four weeks of untreated food. The hindguts of the animals were removed prior to analysis to exclude food material from the body. Benzo[a]pyrene concentrations were log-normally distributed among the individuals. The high inter-individual variation in benzo[a]pyrene content could not be explained from differences in sex, the estimated amount of food in the hindgut, or the body weight. A one-compartment model fitted to the isopod concentrations estimated an assimilation rate of 2.9 g benzo[a]pyrene/g dwt day, an elimination rate constant of 1.1/day and an equilibrium concentration of 2.5 g benzo[a]pyrene/g dwt. According to the model 68% of the isopod population had an equilibrium concentration between 1.0 and 7.2 g benzo[a]pyrene/g dwt day with a benzo[a]pyrene half-life ranging between 0.4 and 1.3 days. The assimilation efficiency was estimated at 20 to 40% of the ingested benzo[a]pyrene. The tissue distribution of benzo[a]pyrene was investigated in a separate experiment. Trace levels of benzo[a]pyrene were detected in haemolymph samples, demonstrating absorption and transport of the compound in the isopod. It is concluded that dietary benzo[a]pyrene is available for uptake to the isopod and that low residues of the compound observed in field isopods are the result of a high elimination rate rather than a reduced bioavailability. As PAHs from soil appear to be available to soil invertebrates, the widespread contamination of the soil from atmospheric emissions is of some concern, especially since the observed elimination may be linked to metabolic activation of PAHs.     

Lysosomal membrane stability in laboratory- and field-exposed terrestrial isopods Porcellio scaber (Isopoda, Crustacea)

Two established methods for assessment of the cytotoxicity of contaminants, the lysosomal latency (LL) assay and the neutral red retention (NRR) assay, were successfully applied to in toto digestive gland tubes (hepatopancreas) of the terrestrial isopod Porcellio scaber (Isopoda, Crustacea). In vitro exposure of isolated gland tubes to copper was used as a positive control to determine the performance of the two methods. Lysosomal latency and the NRR assay were then used on in vivo (via food) laboratory-exposed animals and on field populations. Arbitrarily selected criteria for determination of the fitness of P. scaber were set on the basis of lysosomal membrane stability (LMS) as assessed with in toto digestive gland tubes. Decreased LMS was detected in animals from all polluted sites, but cytotoxicity data were not in agreement with concentrations of pollutants. Lysosomal membrane stability in the digestive gland tubes of animals from an environment in Idrija, Slovenia that was highly polluted with mercury (260 microg/g dry wt food and 1,600 microg/g dry wt soil) was less affected than LMS in laboratory animals fed with 5 and 50 microg Hg/g dry weight for 3 d. This probably indicates tolerance of P. scaber to mercury in the mercury-polluted environment and/or lower bioavailability of environmental mercury. In animals from the vicinity of a thermal power plant with environmental mercury concentrations three to four orders of magnitude lower than those in Idrija, LMS was severely affected. In general, the LL assay was more sensitive than the NRR assay. The LMS assay conducted on digestive gland tubes of terrestrial isopods is highly recommended for integrated biomarker studies.     

Removal of Copper (VI) from Aqueous Solution by Ag/TiO2 Photocatalysis

No abstract available.     

Fate of benzo(a)pyrene in the digestive tract. 2. Appearance of metabolites

The degradation of the B(a)P - mainly by oxidative way - began in the stomach and greatly developed in the intestine. The quinones and other hydrosoluble derivatives were the main metabolites of the B(a)P digestive tractus. The quinones predominated in stomach tissue, but the most hydrosoluble metabolites also were present in this wall. In the intestinal content, these hydrosoluble metabolites were very abundant; they seemed easily absorbable by the intestinal wall. Conversely, the quinones were excreted in faeces. A reduced metabolite was formed in intestinal and faecal contents.     

Fe3+/TiO2-xNx太阳光下降解亚甲基蓝的研究

目的:采用溶胶-凝胶法制备一系列不同Fe3 掺杂量的复合纳米Fe3 /TiO2-xNx光催化剂,建立以太阳为光源高效降解亚甲基蓝的反应体系。方法:利用UV-V is-DR s和XRD对其光谱学特征进行研究。以亚甲基蓝(MB)的光催化降解反应为模型,研究Fe3 /TiO2-xNx光催化剂的催化活性及其影响因素,探讨了采用太阳光为光源降解MB的可行性。结果:x(Fe3 )为0.4%,光催化剂用量为2 g/L,初始MB浓度为1×10-6mol/L,初始pH值为8,初始H2O2浓度为6 mmol/L,采用太阳光照射4 h,MB降解率可达87%。结论:自制光催化剂能有效利用太阳光,高效降解水中亚甲基蓝。     

Effects of X-ray and carbon ion beam irradiation on membrane permeability and integrity in Saccharomyces cerevisiae cells

Saccharomyces cerevisiae has served as a eukaryotic model in radiation biology studies of cellular responses to ionizing radiation (IR). Research in this field has thus far mainly been focused on DNA strand breaks, DNA base damage, or inhibition of protein activity. However, the effects of IR on S. cerevisiae cell membranes have barely been studied. Here, we investigated the changes in the permeability and integrity of S. cerevisiae cell membranes induced by high–linear energy transfer carbon ion (CI) beam or low–linear energy transfer X-ray. After CI exposure, protein elution and nucleotide diffusion were more pronounced than after X-ray treatment at the same doses, although these features were most prevalent following irradiation doses of 25–175 Gy. Flow cytometry of forward scatter light versus side scatter light and double-staining with fluorescein diacetate and propidium iodide showed that CI and X-ray irradiation significantly affected S. cerevisiae cell membrane integrity and cellular enzyme activity compared with untreated control cells. The extent of lesions in CI-irradiated cells, which exhibited markedly altered morphology and size, was greater than that in X-ray-irradiated cells. The relationships between permeabilized cells, esterase activity, and non-viable cell numbers furthermore indicated that irradiation-induced increases in cell permeabilization and decreases in esterase activity are dependent on the type of radiation and that these parameters correspond well with cell viability. These results also indicate that the patterns of cell inactivity due to X-ray or CI irradiation may be similar in terms of cell membrane damage.     

Cell killing and radiosensitization by caffeic acid phenethyl ester (CAPE) in lung cancer cells

Caffeic acid phenethyl ester (CAPE) is a biologically active ingredient of honeybee propoplis. The cytotoxicity and radiation sensitization effects of CAPE were evaluated in human lung cancer A549 cells and normal lung fibroblast WI-38 cells. A549 cells treated with 6 microg/ml CAPE showed marked growth inhibition (60%) at 48 hr after treatments. During the same time, the number of viable cells decreased to 46% of the control value. In contrast, WI-38 cells showed 20% growth inhibition with no change in the number of viable cells under the same treatment conditions. At 72 hr after CAPE treatment (6 microg/ml), the percentage of apoptotic cells in A549 cultures increased significantly to 67% and an S/G2 arrest was also detected in the culture. Furthermore, there was a significant decrease in the level of intracellular glutathione and hydrogen peroxide contents within one hr after CAPE treatment, and the expression of cyclin B1 was reduced 6 hr after treatment. The radiation sensitization effect of CAPE on A549 cells was determined from the clonogenic survival curves, and the results showed a small but significant difference in radiation survival between cells treated with or without CAPE. Taken together, our results suggest that the effects of CAPE on differential cytotoxicity, apoptosis, and radiosensitization are associated with glutathione depletion that occurred shortly after treatments.     

用细胞转移法研究苯并（a）芘损伤机理

ＢＡＬＡ／Ｃ雌性小鼠一次腹腔注射２００ｍｇ／ｋｇ体重的苯并（ａ）芘（Ｂ（ａ）ｐ）．体液免疫功能受到明显的抑制，脾ＩｇＭ—ＰＦＣ和ＩｇＧ－ＰＦＣ抑制率分别为４４％和６４％．如果给Ｂ（ａ）ｐ染毒小鼠输入正常小鼠的Ｔ细胞或Ｂ细胞，可使受Ｂ（ａ）ｐ抑制的小鼠免疫功能恢复到接近对照组的水平．说明Ｂ（ａ）Ｐ可同时作用于Ｔ细胞和Ｂ细胞．     

The manifestations of toxicity of nanoparticles (a review)

The analysis of the data available in the literature has shown that nanoparticles (NP) have a high toxicity than usual microparticles, can penetrate unchanged across the cell barriers, the blood-brain barrier into the central nervous system, circulate and accumulate in the organs and tissues, by inducing more significant pathomorphological lesions in the visceral organs, and have a long elimination half-life. The toxicity of HPs is determined by their shape and sizes; moreover, minute fusiform particles cause more destructive effects than similar spherical particles; upon exposure, there is a clear dose-effect relationship. According to exposure to NPs, the classical target organs for the latter are the lung, liver, kidney, brain, gastrointestinal tract.     

不同粒径纳米Fe2O3的细胞毒性及氧化作用

目的 从细胞半数抑制浓度ICso和氧化作用的角度探讨不同粒径Fe2O3纳米粒子细胞毒性的差异。方法 将8，13和37nm3个不同尺寸的Fe2O3纳米粒子以不同剂量、时间作用于中国仓鼠肺成纤维细胞(CHL)，用活细胞计数法求得不同尺寸粒子的IC50并绘制细胞生长抑制曲线。硫代巴比妥酸法测定丙二醛(MDA)含量，黄嘌呤氧化酶法测定超氧化歧化酶(SOD)活性。结果 (1)3种尺寸的纳米粒子在一定浓度范围内，剂量与细胞抑制率呈现剂量-反应关系，而超过这一范围后，量效关系消失。(2)在量效相关的浓度范围内，3种尺寸纳米粒子的IC50分别为IC50(8nm)=279．585μg／ml，IC50(13nm)=254．739μg/ml，IC50(37nm)=561．237μg/ml。(3)Fe2O3纳米粒子可引起CHL细胞的氧化应激反应，且与作用时间有关。但MDA、SOD值变化与纳米粒子尺才、作用剂量之间无明显的量效关系。结论 不同粒径的Fe2O3纳米粒子在细胞毒性上表现出一定的差异，Fe2O3纳米粒子可引起CHL细胞的氧化应激反应，从时效性分析推论其细胞毒性与氧化性存在一定的关联。     

Immunity to Chlamydia pneumoniae induced by vaccination with DNA vectors expressing a cytoplasmic protein (Hsp60) or outer membrane proteins (MOMP and Omp2)

Immune responses induced by intramuscular DNA immunization with Chlamydia pneumoniae genes coding for the major outer membrane protein (MOMP), cysteine-rich outer membrane protein 2 (Omp2) or the heat shock protein 60 (Hsp60) were studied. BALB/c mice were vaccinated intramuscularly three times at 3-week intervals and challenged intranasally 2 weeks after the last injection. Immunization with pmomp or phsp60 showed 1.2-1.5 log reduction in the mean lung bacterial counts after the challenge. Specific antibodies were detected only in sera of the mice immunized with pomp2 and phsp60. Although immunization with pomp2 resulted in a strong serum antibody response against Omp2 protein, it failed to protect the mice. Immunization with any of the three vaccines did not reduce the severity of histologically assessed pneumonia, but resulted in significantly higher lymphoid reaction in the lung indicating immunological memory.