Development of enzyme-linked immunosorbent assays for plasma vitellogenin in Chinese rare minnow (Gobiocypris rarus).

Due to the wide occurrence of endocrine disrupting chemicals in the environment, it is much of importance to develop high throughput screening method for the analysis of this kind of pollutants. Using anion-exchange membrane chromatography, vitellogenin (VTG) from the plasma of 17ß-estradiol (E(2)) treated Chinese rare minnow was rapidly purified within 15 min. Both polyclonal antibody (PcAb) and monoclonal antibody (McAb) against rare minnow VTG (R-VTG) were prepared in rabbit and Balb/c mice, respectively. The competitive enzyme-linked immunosorbent assays (ELISA) based on either PcAb or McAb were developed to identify and quantify R-VTG in the plasma, and these two methods showed similar characteristics. The detection limits of both assays were lower than 3 ng mL(-1) with the working ranges covering three magnitudes. The recovery efficiencies of PcAb and McAb based ELISA were 104.2% and 102.6%, respectively; and the intra-assay and inter-assay of these two assays were 6.2% and 9.2%, 8.6% and 12.8%, respectively. These results indicated that the described competitive ELISA methods were sensitive and valuable tools for quantifying vitellogenin in rare minnow plasma. These methods were then applied to measure R-VTG concentrations in plasma of male fish exposed to a series of E(2) concentrations. When E(2) levels were less than 10 ng L(-1), R-VTG levels in plasma were comparable to that in solvent control, while R-VTG levels significantly increased 15-folds and 350-folds, respectively when E(2) exposure concentrations were controlled at 10 and 50 ng L(-1). The high sensitivity of Chinese rare minnow to E(2) was demonstrated, making it a valuable model species to study environmental estrogens.

Sorption to dissolved humic acid and its impacts on the toxicity of imidazolium based ionic liquids.

Two typical ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride ([C4MIM]Cl) and 1-octyl-3-methylimidazolium chloride ([C8MIM]Cl), are demonstrated to associate strongly with dissolved organic matter (DOM) with distribution coefficients (KDOC) in the range of 10(4.2) to 10(4.6) for Aldrich humic acid (used as model DOM). With the increase of humic acid concentration to 11 µg/mL DOC (dissolved organic carbon), the free fraction (ratio of freely dissolved to total concentration) of [C4MIM]Cl and [C8MIM]Cl reduced to about 0.85 and 0.79, respectively. This reduction of freely dissolved concentration gave rise to remarkable reduction of bioavailability and toxicity of the two ILs. MTT assay with HepG2 cell lines showed that the EC50 values were 459 µmol/L for [C4MIM]Cl and 12 µmol/L for [C8MIM]Cl, respectively, and the cell viability increased about 50% in the presence of trace amount of humic acid (1 µg/mL DOC). The SOS/umu test indicated mutagenicity for [C4MIM]Cl at levels above 664 µmol/L, and the genotoxicity was diminished with the addition of trace humic acid (0.00000374-0.374 µg/mL DOC). The studied ILs showed acute toxicity toward model fish medaka with a 96 h median lethal concentration (LC50) of 2254 µmol/L for [C4MIM]Cl and 366 µmol/L for [C8MIM]Cl. The addition of humic acid (5.49 µg/mL DOC for [C8MIM]Cl, 1.37 µg/mL DOC for [C4MIM]Cl) to IL solutions reduced the death rate of medaka to a minimum value of ∼25% of that at zero DOC. Our results suggest that DOM may play an important role in determining the environmental fate and toxicity of imidazolium-based ILs, and its effects should be taken into account in assessing the environmental risk of ILs.

Metal cation mediated-capillary electrophoresis of nucleic acids.

Nucleic acid electrophoresis separation heavily depends upon gel or nongel sieving matrix. Here we propose a metal ion mediated-capillary electrophoresis (MCE-CE) by utilizing the nonspecific interactions of Mg(2+) and Ca(2+) and demonstrate the size, conformation, or sequence based separation and characterization of versatile nucleic acid molecules in free solution. Mg(2+) and Ca(2+) can induce DNA separation at the concentrations as low as 100 and 50 muM, respectively. Noteworthy, the two naturally occurring polymorphisms of one base substitution that may change the secondary folding structure or base stacking can be discriminated by MCM-CE, showing its unique capability of resolving length-identical but conformation-different ssDNA. Benefiting from the achieved separation, we further demonstrate that the folding conformation of oligomers and its change caused by single base substitution can be promptly sensed by online coupled fluorescence polarization. We anticipate that this method will be applicable in length polymorphism analysis, single-strand polymorphism analysis, hybridization analysis, microRNA analysis, and study of protein-nucleic acid interactions and the conformation-function relationship.

Interacting effects of tributyltin and 17beta-estradiol in male Chinese loach (Misgurnus anguillicaudatus).

In this study, male Chinese loaches in a semistatic waterborne exposure system were used to study the effects of tributyltin (TBT) on vitellogenin (Vtg) production induced by 17beta-estradiol (E2), TBT accumulation and distribution in tissues, and the effects of E2 on the distribution of TBT. The results demonstrate that TBT does not induce the synthesis of Vtg in male Chinese loach and that TBT could significantly inhibit Vtg production induced by E2, after exposure to binary mixtures of E2 and TBT for 14 days. TBT was found to accumulate in the liver, kidney, gills, intestines, and muscles of male Chinese loach, wherein the liver, kidney, gills, and intestines were found to have the most TBT accumulation. The existence of E2 did not significantly affect tissue distribution of TBT.

Elemental selenium particles at nano-size (Nano-Se) are more toxic to Medaka (Oryzias latipes) as a consequence of hyper-accumulation of selenium: a comparison with sodium selenite.

Recent studies have shown that elemental selenium particles at nano-size (Nano-Se) exhibited comparable bioavailability and less toxicity in mice and rats when compared to sodium selenite, selenomethinine and methylselenocysteine. However, little is known about the toxicity profile of Nano-Se in aquatic animals. In the present study, toxicities of Nano-Se and selenite in selenium-sufficient Medaka fish were compared. Selenium bioaccumulation and subsequent clearance in fish livers, gills, muscles and whole bodies were examined after 10 days of exposure to Nano-Se and selenite (100 microg Se/L) and again after 7 days of depuration. Both forms of selenium exposure effectively increased selenium concentrations in the investigated tissues. Surprisingly, Nano-Se was found to be more hyper-accumulated in the liver compared to selenite with differences as high as sixfold. Selenium clearance of both Nano-Se and selenite occurred at similar ratios in whole bodies and muscles but was not rapidly cleared from livers and gills. Nano-Se exhibited strong toxicity for Medaka with an approximately fivefold difference in terms of LC(50) compared to selenite. Nano-Se also caused larger effects on oxidative stress, most likely due to more hyper-accumulation of selenium in liver. The present study suggests that toxicity of nanoparticles can largely vary between different species and concludes that the evaluation of nanotoxicology should be carried out on a case-by-case basis.