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Summary Our knowledge of copy number evolution during the expansion of primary breast tumors is limited 1 , 2 . To investigate this process, we developed a single cell, single-molecule DNA sequencing method and performed copy number analysis of 16,178 single cells from 8 triple-negative breast cancers (TNBCs) and 4 cell lines. Our data shows that breast tumors and cell lines are comprised of a large milieu of subclones (7–22) that are organized into a few (3–5) major superclones. Evolutionary analysis suggests that after clonal TP53 mutations, multiple LOH events and genome doubling, there was a period of transient genomic instability followed by ongoing copy number evolution during the primary tumor expansion. By subcloning single daughter cells in culture, we show that tumor cells re-diversify their genomes and do not retain isogenic properties. These data show that TNBCs continue to evolve chromosome aberrations and maintain a reservoir of subclonal diversity during primary tumor growth.

No other country has undergone health care reforms as dramatic as China's. Starting in 1978, China reformed its health system from a governmental, centrally planned, and universal system to a heavily market-based one. Now, three decades later, the Chinese government openly acknowledges that the reforms failed and seeks new directions. This paper adds to the literature by examining China's health care from a system perspective, describing its health services delivery, access, outcomes, and population health in the post-reform era. It also identifies the main issues in the current system and highlights the key lessons learned from China's reform process.

The formation and release of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) from the incineration of electronic wastes (e-waste) that contain brominated flame retardants (BFRs) are a concern. However, studies on the determination of PBDD/Fs in environmental samples collected from e-waste recycling facilities are scarce. In this study, 11 2,3,7,8-substituted PBDD/Fs and 10 polybrominated diphenyl ether (PBDE) congeners were determined in electronic shredder waste, workshop-floor dust soil, and leaves (of plants on the grounds of the facility) from a large-scale e-waste recycling facility and in surface soil from a chemical-industrial complex (comprising a coke-oven plant, a coal-fired power plant, and a chlor-alkali plant) as well as agricultural areas in eastern China. Total PBDD/F concentrations in environmental samples were in the range of 113-818 pg/g dry wt (dw) for leaves, 392-18500 pg/g dw for electronic shredder residues, 716-800000 pg/g dw for soil samples, and 89600-pg/g dw for workshop-floor dust from the e-waste recycling facility and in a range from nondetect (ND) to 427 pg/g dw in soil from the chemical-industrial complex. The highest mean concentrations of total PBDD/Fs were found in soil samples and workshop-floor dust from the e-waste recycling facility. The dioxin-like toxic equivalent (measured as TEQ) concentrations of PBDD/Fs were greater than the TEQs of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) reported in our previous study for the same set of samples. The concentrations of PBDFs were several orders of magnitude higher than the concentrations of PBDDs in samples from the e-waste facility or from soil from the chemical-industrial complex. A significant correlation was found between the concentrations of sigmaPBDD/Fs and sigmaPBDEs (r = 0.769, p < 0.01) and between sigmaPBDD/Fs and the previously reported sigmaPCDD/F concentrations (r = 0.805, p < 0.01). The estimated daily human intakes of TEQs contributed by PBDD/Fs via soil/dust ingestion and dermal exposures in e-waste recycling facilities were higher than the intakes of TEQs contributed by PCDD/ Fs, calculated in our previous study.

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Environmental pollution arising from electronic waste (e-waste) disposal and recycling has received considerable attention in recent years. Treatment, at low temperatures, of e-wastes that contain polyvinylchloride and related polymers can release polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Although several studies have reported trace metals and polybrominated diphenyl ethers (PBDEs) released from e-waste recycling operations, environmental contamination and human exposure to PCDD/Fs from e-waste recycling operations are less well understood. In this study, electronic shredder waste and dust from e-waste facilities, and leaves and surface soil collected in the vicinity of a large scale e-waste recycling facility in Taizhou, Eastern China, were analyzed for total PCDD/ Fs including 2,3,7,8-substituted congeners. We also determined PCDD/Fs in surface agricultural soils from several provinces in China for comparison with soils from e-waste facilities. Concentrations of total PCDD/Fs were high in all of the matrices analyzed and ranged from 30.9 to 11400 pg/g for shredder waste, 3460 to 9820 pg/g dry weight for leaves, 2560 to 148000 pg/g dry weight for workshop-floor dust, and 854 to 10200 pg/g dry weight for soils. We also analyzed surface soils from a chemical industrial complex (a coke-oven plant, a coal-fired power plant, and a chlor-alkali plant) in Shanghai. Concentrations of total PCDD/Fs in surface soil (44.5-531 pg/g dry wt) from the chemical industrial complex were lower than the concentrations found in soils from e-waste recycling plants, but higher than the concentrations found in agricultural soils. Agricultural soils from six cities in China contained low levels (3.44-33.8 pg/g dry wt) of total PCDD/Fs. Profiles of dioxin toxic equivalents (TEQs) of 2,3,7,8-PCDD/Fs in soils from e-waste facilities in Taizhou differed from the profiles found in agricultural soils. The estimated daily intakes of TEQs of PCDD/ Fs via soil/dust ingestion and dermal exposure (2.3 and 0.363 pg TEQ/kg bw/day for children and adults, respectively) were 2 orders of magnitude higher in people at e-waste recycling facilities than in people at the chemical industrial site (0.021 and 0.0053 pg TEQ/kg bw/day for children and adults, respectively), implying greater health risk for humans from dioxin exposures at e-waste recycling facilities. The calculated TEQ exposures for e-waste workers from dust and soil ingestion alone were 2-3 orders of magnitude greater than the exposures from soils in reference locations.

Water availability is the most influential factor affecting plant carbon (δ 13C) and nitrogen (δ 15N) isotope composition in arid and semi-arid environments. However, there are potential differences among locations and/or species in the sensitivity of plant δ 13C and δ 15N to variation in precipitation, which are important for using stable isotope signatures to extract paleo-vegetation and paleo-climate information. We measured δ 13C and δ 15N of plant and soil organic matter (SOM) samples collected from 64 locations across a precipitation gradient with an isotherm in northern China. δ 13C and δ 15N for both C3 and C4 plants decreased significantly with increasing mean annual precipitation (MAP). The sensitivity of δ 13C to MAP in C3 plants (-0.6±0.07‰/100 mm) was twice as high as that in C4 plants (−0.3±0.08‰/100 mm). Species differences in the sensitivity of plant δ 13C and δ 15N to MAP were not observed among three main dominant plants. SOM became depleted in 13C with increasing MAP, while no significant correlations existed between δ 15N of SOM and MAP. We conclude that water availability is the primary environmental factor controlling the variability of plant δ 13C and δ 15N and soil δ 13C in the studied arid and semi-arid regions. Carbon isotope composition is useful for tracing environmental precipitation changes. Plant nitrogen isotope composition can reflect relative openness of ecosystem nitrogen cycling.

Abstract:Survival of desert riparian vegetation along the middle and lower reaches of the Tarim River in China depends almost entirely on groundwater. The aim of this project was to study the effect of various water table levels on desert riparian forest vegetation and to determine the groundwater threshold under which desert riparian forest vegetation can grow normally. Using data collected from 2 years (2006)(2007) of monitoring (groundwater, vegetation plots, and soil profiles) of the middle and lower reaches of the Tarim River, the relationship between vegetation and environmental factors was analysed using detrended canonical correspondence analysis (DCCA). The average depth of the groundwater table at the study sites was divided into six ranges (0-2, 2-4, 4-6, 6-8, 8-10, and >10 m) to compare the influence of groundwater level on species diversity. Using the ecological suitability theory and data from previous studies of several major plant species in the study area, a logarithm normal distribution relation model was built between the growth of plants and the depth of groundwater. The results of DCCA ordination indicated that groundwater depth (GWD) and soil moisture are the crucial environmental factors affecting the distribution of plants. Species diversity was the highest at the 2-4 m level, followed by the 4-6 m level, and then the 0-2 m level. When the groundwater level dropped to below 6 m, species diversity decreased greatly, and the slope of Hill's index (diversity ordering) tended to level off. Thus, the optimum groundwater level for major plant growth is 2-4 m and the threshold GWD is about 6 m. To restore the vegetation and ecosystem of the lower reaches of the Tarim River, the water table must be kept at a minimum of 6 m in depth. It should also be maintained at 2-4 m in the vicinity of the water way and at 4-6 m for the rest of this arid area.