Contact electrification between water and a solid surface is crucial for physicochemical processes at water–solid interfaces. However, the nature of the involved processes remains poorly understood, especially in the initial stage of the interface formation. Here we report that H 2 O 2 is spontaneously produced from the hydroxyl groups on the solid surface when contact occurred. The density of hydroxyl groups affects the H 2 O 2 yield. The participation of hydroxyl groups in H 2 O 2 generation is confirmed by mass spectrometric detection of 18 O in the product of the reaction between 4-carboxyphenylboronic acid and 18 O–labeled H 2 O 2 resulting from 18 O 2 plasma treatment of the surface. We propose a model for H 2 O 2 generation based on recombination of the hydroxyl radicals produced from the surface hydroxyl groups in the water–solid contact process. Our observations show that the spontaneous generation of H 2 O 2 is universal on the surfaces of soil and atmospheric fine particles in a humid environment.

DNA methylation has been proven to be a critical epigenetic mark important for various cellular processes. Here, we report that redox-active quinones, a ubiquitous class of chemicals found in natural products, cancer therapeutics and environment, stimulate the conversion of 5mC to 5hmC in vivo, and increase 5hmC in 5751 genes in cells. 5hmC increase is associated with significantly altered gene expression of 3414 genes. Interestingly, in quinone-treated cells, labile iron-sensitive protein ferritin light chain showed a significant increase at both mRNA and protein levels indicating a role of iron regulation in stimulating Tet-mediated 5mC oxidation. Consistently, the deprivation of cellular labile iron using specific chelator blocked the 5hmC increase, and a delivery of labile iron increased the 5hmC level. Moreover, both Tet1/Tet2 knockout and dimethyloxalylglycine-induced Tet inhibition diminished the 5hmC increase. These results suggest an iron-regulated Tet-dependent DNA demethylation mechanism mediated by redox-active biomolecules.

Information on placental transfer and adverse outcomes of short-chain per- and polyfluoroalkyl substance (PFASs) is limited, and factors responsible for PFAS placental transfer are still unclear. In the present study, concentrations of 21 PFASs were analyzed in 132 paired maternal and cord serum samples collected from residents in Beijing, China, and the placental transfer efficiency (PTE) of each PFAS was calculated. PTEs of short-chain perfluoroalkyl acids (PFAAs), including PFBA (146%), PFBS (97%), PFPeA (118%), and PFHxA (110%), were first reported, and a complete U-shaped trend of PTEs from C4 to C13 of perfluoroalkyl carboxylic acids (PFCAs) was obtained. Positive association between maternal weight and PTE of perfluorooctanesulfonate (PFOS) (p < 0.05) and negative association between maternal PFBA concentration and birth length (p < 0.01) were observed. Using in vitro experiments, we further determined equilibrium dissociation constants (K ds) of human serum albumin (HSA)–PFAS complexes (K d‑HP), serum proteins–PFAS complexes (K d‑SP), and liver-fatty acid binding protein (L-FABP)–PFAS complexes (K d‑LP) and found that they were all significantly correlated with PTEs of PFASs. The correlation coefficient was 0.92, 0.89, and 0.86, respectively (p < 0.01 in all three tests), suggesting that K ds of protein (serum)–PFAS complexes can play an important role in trans-placental transfer of PFASs in human and K d‑HP plays a pivotal role.

Extensive use of bisphenol A and its analogues has caused increasing concern over the potential adverse health impacts of these chemicals. In this study, the presence and profiles of 13 bisphenols (BPs) were investigated in 52 municipal sewage sludge samples collected from 30 cities in China. Tetrabromobisphenol A was the most frequently observed analogue (geometric mean: 20.5 ng/g dw). Bisphenol A (4.69 ng/g dw), bisphenol S (3.02 ng/g dw), and bisphenol F (3.84 ng/g dw) were found with similar frequency. Other BP analogues such as tetrachlorobisphenol A, bisphenol AF, bisphenol E, and dihydroxybiphenyl were identified for the first time in sewage sludge in China. Significant correlations were found among BP concentrations, but no relationships were found with wastewater treatment plant characteristics. Profiles of the relative estradiol equivalents suggested that the estrogenic potential of BP mixtures may be associated with the occurrence and contributions of specific analogues.

a b s t r a c tGraphene oxide (GO) has been extensively explored as a promising nanomaterial for applications in biology because of its unique properties. Therefore, systematic investigation of GO toxicity is essential to determine its fate in the environment and potential adverse effects. In this study, acute toxicity, oxidative stress and immunotoxicity of GO were investigated in zebrafish. No obvious acute toxicity was observed when zebrafish were exposed to 1, 5, 10 or 50 mg/L GO for 14 days. However, a number of cellular alterations were detected by histological analysis of the liver and intestine, including vacuolation, loose arrangement of cells, histolysis and disintegration of cell boundaries. As evidence for oxidative stress, malondialdehyde levels and superoxide dismutase and catalase activities were increased and glutathione content was decreased in the liver after treatment with GO. GO treatment induced an immune response in zebrafish, as demonstrated by increased expression of tumor necrosis factor ␣, interleukin-1 ␤, and interleukin-6 in the spleen. Our findings demonstrated that GO administration in an aquatic system can cause oxidative stress and immune toxicity in adult zebrafish. To our knowledge, this is the first report of immune toxicity of GO in zebrafish.

A high-resolution physical map targeting a cluster of yield-related QTLs on the long arm of rice chromosome 9 has been constructed across a 37.4 kb region containing seven predicted genes. Using a series of BC3F4 nearly isogenic lines (NILs) derived from a cross between the Korean japonica cultivar Hwaseongbyeo and Oryza rufipogon (IRGC 105491), a total of seven QTLs for 1,000-grain weight, spikelets per panicle, grains per panicle, panicle length, spikelet density, heading date and plant height were identified in the cluster (P

Novel per-and polyfluoroalkyl substances (PFASs) in various environmental media have attracted increasing attention; however, the information regarding PFASs exposure in pregnant women and fetuses is insufficient. In this study, we built and applied suspect and nontarget screening strategies based on the mass difference of the CF 2 , CF 2 O, and CH 2 CF 2 units to select potential novel PFASs from 117 paired maternal and cord sera. In total, 10 legacy PFASs and 19 novel PFASs from 10 classes were identified to be above confidence levels 3, among which 14 were not previously reported in human serum. Novel PFASs accounted for a considerable percentage of total PFASs in pregnant women and can be transferred to fetuses at non-negligible concentrations (i.e., 27.9% and 30.3% of total PFAS intensities in maternal and cord sera, respectively). The transplacental transfer efficiency (TTE) of PFASs showed a U-shape trend in the series of perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonic acids, and unsaturated perfluorinated alcohols. The TTE of novel PFASs is suggested to be structure-dependent, based on a flexible docking experiment. This study provides comprehensive TTE information on legacy and novel PFASs for the first time, and additional toxicity studies are needed to evaluate the risk of novel PFASs further.

A quantitative trait locus (QTL) for grain weight (GW) was detected near SSR marker RM210 on chromosome 8 in backcross populations derived from a cross between the Korean japonica cultivar Hwaseongbyeo and Oryza rufipogon (IRGC 105491). The O. rufipogon allele increased GW in the Hwaseongbyeo background despite the fact that O. rufipogon was the small-seeded parent. Using sister BC(3)F(3) near-isogenic lines (NILs), gw8.1 was validated and mapped to a 6.1 cM region in the interval between RM42 and RM210 (P < or = 0.0001). Substitution mapping with eight BC(3)F(4) sub-NILs further narrowed the interval containing gw8.1 to about 306.4 kb between markers RM23201.CNR151 and RM30000.CNR99. A yield trial using homozygous BC(3)F(4) sister sub-NILs and the Hwaseongbyeo recurrent parent indicated that the NIL carrying an O. rufipogon chromosome segment across the entire gw8.1 target region out-yielded its sister NIL (containing Hwaseongbyeo chromosome in the RM42-RM210 interval) by 9% (P=0.029). The higher-yielding NIL produced 19.3% more grain than the Hwaseongbyeo recurrent parent (P=0.018). Analysis of a BC(3)F(4) NIL indicated that the variation for GW is associated with variation in grain shape, specifically grain length. The locus, gw8.1 is of particular interest because of its independence from undesirable height and grain quality traits. SSR markers tightly linked to the GW QTL will facilitate cloning of the gene underlying this QTL as well as marker-assisted selection for variation in GW in an applied breeding program.