Species-dependent effects of the phenolic herbicide ioxynil with potential thyroid hormone disrupting activity: modulation of its cellular uptake and activity by interaction with serum thyroid hormone-binding proteins

Ioxynil, a phenolic herbicide, is known to exert thyroid hormone (TH) disrupting activity by interfering with TH-binding to plasma proteins and a step of the cellular TH-signaling pathway in restricted animal species. However, comparative studies are still lacking on the TH disruption.We investigated the interaction of [¹²⁵I]ioxynil with serum proteins from rainbow trout, bullfrog, chicken, pig, rat, and mouse, using native polyacrylamide gel electrophoresis. Candidate ioxynil-binding proteins, which included lipoproteins, albumin and transthyretin (TTR), differed among the vertebrates tested. Rainbow trout and bullfrog tadpole serum had the lowest binding activity for ioxynil, whereas the eutherian serum had the highest binding activity. The cellular uptake of, and response to, ioxynil were suppressed by rat serum greater than by tadpole serum. The cellular uptake of [¹²⁵I]ioxynil competed strongly with phenols with a single ring, but not with THs. Our results suggested that ioxynil interferes with TH homeostasis in plasma and with a step of cellular TH-signaling pathway other than TH-uptake system, in a species-specific manner.     

Water at interfaces

Electrolyte cations and anions in aqueous solutions are hydrogen bond breaker. We found that most of anions are strong hydrogen bond breaker whereas cations are not. Further, the electro-reduction of Mg(H₂O)₆²⁺ to Mg(OH)₂ and the growth of the Mg(OH)₂ were observed on Au electrode surface at negative electrode potential. Water molecules in an electric double layer exhibit an ordered and a disordered structure at negative and pzc (point of zero charge) potentials, respectively. Therefore, electrode potential polarization (negative or pzc potential application) from an equilibrium potential operates an electrified interface to cause increased or decreased ordering, orientation and charge transfer of water molecules as well as dissociation of water on the electrode surface.     

基于2H&18O和水化学成分的永定河流域地下水循环特征解析

运用环境同位素和水化学成分作为水循环研究的示踪剂, 揭示了永定河流域中下游地下水 循环特征。通过现场调查并对浅层和深层地下水采样, 进行室内水化学和氢氧同位素组成测定, 分 析了流域内深层和浅层地下水的氢氧同位素和水化学组成的空间分布规律和演化趋势, 揭示了流 域地下水循环特征。结果表明, 降水是山前地下水的主要补给源, 地下水在接受降水的补给后经过 了不同程度的蒸发作用, 山区受蒸发影响较小, 平原区较大, 尤其是平原区浅层地下水呈现出强烈 的蒸发浓缩作用; 水化学特征表现为自西部山区到山前平原至滨海平原, 自浅层到深层, 地下水的 矿化度逐渐升高; 平原区浅层和深层地下水含水层之间存在明显的越流补给现象; 沿海地区未发现 海水入侵现象。     

芦竹抑藻物质的初步分离及抑制铜绿微囊藻的效果

采用乙酸乙酯提取芦竹(Arundo donax Linn.)得到高效抑藻粗提物,其对产毒铜绿微囊藻的半效应抑制浓度(EC50.6d)为50mg·1-1.粗提物经溶剂萃取分离得到中/碱性物质及酸性物质.活性分析表明,酸性物质有显著抑制铜绿微囊藻的活性.通过酸性氧化铝柱层析进一步分离酸性物质,得到三组弱极性抑藻物质及一组强极性抑藻物质.培养3d后,四组抑藻物质在10mg·1-1时的抑藻率分别为82%,83%,100%以及70%.     

Prospects for a self-sustainable sewage treatment system: a case study on full-scale UASB system in India's Yamuna River Basin

The government of India decided to launch a project to implement 16 full-scale Upflow Anaerobic Sludge Blanket (UASB) reactors (with a total capacity of 598,000 m(3)/d) in the Yamuna River basin under its Yamuna Action Plan (YAP). A polishing pond called the Final Polishing Unit (FPU) was utilized for post-treatment. This paper evaluates the sewage treatment efficiency of the combined system of full-scale UASB reactors and polishing ponds under Indian climatic conditions. Results have shown that the effluent from the sewage treatment plants (STPs) investigated failed to comply with applicable discharge standards in terms of BOD, SS, and fecal coliform removal. Therefore, it is proposed that such proper operation and maintenance as removing excess sludge and scum be conducted in order to increase treatment efficiency. Moreover, trained and experienced workers are also required to operate and maintain the systems, along with a scientific approach.     

Reaction hazards of triethylaluminum under closed conditions

We evaluate the reaction hazards of triethylaluminum (TEA) under closed conditions for safe treatment of aluminum alkyls. The explosive reactions of TEA are difficult to be estimated using thermal analysis because the estimate reactions are too slow under these conditions. The results of our closed vessel tests and chemical equilibrium calculations show that the TEA and water system mixture in closed conditions decomposes into lower-molecular-weight compounds than the products by using well-known hydrolysis of TEA. The present work also demonstrates that large temperature and pressure increases could occur because of the existence of TEA and aluminum hydroxide. Since aluminum hydroxide contains water as alumina hydrates, aluminum hydroxide could have been the source of water at high temperatures and could have contributed to the mixed reaction between TEA and water.     

Changes in methylmercury accumulation in the brain of rat offspring throughout gestation and during suckling

Higher methylmercury (MeHg) accumulation and susceptibility to toxicity in the fetus than in the mother at parturition is well known. However, the degree of MeHg accumulation in the brain during the late pregnancy period when the human brain is most vulnerable is not clear. In addition, changes in MeHg accumulation in the developing rat tissues with consecutive exposure throughout gestation and lactation periods have not been well studied. The purposes of this study were to evaluate the changes in MeHg accumulation in the brain and other tissues of the offspring, based on constant and consecutive doses of MeHg to mothers throughout gestation and lactation. Adult female rats were given a diet containing 5?ppm?Hg (as MeHg) for 8 weeks. Then they were mated and subsequently given the same diet throughout gestation and lactation. On embryonic days 18, 20, 22 and at parturition, the concentrations of Hg in the brains of the offspring were approximately 1.5–2.0 times higher than those in the mothers. On the other hand, during the suckling period Hg concentrations in the brain rapidly declined to about 1/10 of that during late pregnancy. Changes in MeHg accumulation in the blood and liver after parturition were similar to those in the brain. Thus, although mothers are subjected to constant and prolonged MeHg exposure throughout both the gestation and lactating periods, the risk to the offspring may be especially high throughout the late gestation period but rapidly decreases during the suckling period