Evaluation and prediction of water conservation of the Yellow river basin in Sichuan Province, China, based on Google Earth Engine and CA-Markov.

The Yellow River Basin in China has the world's most serious soil erosion problem. The Yellow River Basin in Sichuan Province (YRS), as the upper reaches of the Yellow River, and its water conservation (WC) capacity greatly affects the ecological environment of the downstream basin. In recent years, YRS has received more and more attention, and numerous policies have been developed to improve local WC. However, there is a vacancy in the long-term research of WC in the YRS due to the lack of in-situ data. This study quantitatively evaluated the WC of YRS from 2001 to 2020 through Google Earth Engine (GEE) and analyzed the spatio-temporal variations of WC and land cover (LC). CA-Markov predicted the LC and WC in 2025 under three scenarios to assess the contribution of different scenarios to WC. The WC in YRS fluctuated from 1.93 to 6.77 billion m3. The climate is the dominant factor of WC change, but the effect of LC on WC is also evident. The WC capacity increases with vegetation coverage and height. The WC capacity of forests per km2 exceeds 600 mm, while that of grasslands is about 250 mm, and barren can cause around 300 mm of WC loss. In 2025, the WC in YRS may exceed 7.5 billion m3, but the past ecological management mode should be transformed. Improving the quality of land use and converting grasslands to forests is better than reducing cropland to improve WC.

Enhanced biological S0 accumulation by using signal molecules during simultaneous desulfurization and denitrification.

A high rate of elemental sulfur (S0) accumulation from sulfide-containing wastewater has great significance in terms of resource recovery and pollution control. This experimental study used Thiobacillus denitrificans and denitrifying bacteria incorporated with signal molecules (C6 and OHHL) for simultaneous sulfide (S2-) and nitrate (NO3-) removal in synthetic wastewater. Also, the effects on S0 accumulation due to changes in organic matter composition and bacteria proportion through signal molecules were analyzed. The 99.0% of S2- removal and 99.3% of NO3- was achieved with 66% of S0 accumulation under the active S2- removal group. The S0 accumulation, S2- and NO3- removal mainly occurred in 0-48 h. The S0 accumulation in the active S2- removal group was 2.0-6.3 times higher than the inactive S2- removal groups. In addition, S0/SO42- ratio exhibited that S0 conversion almost linearly increased with reaction time under the active S2- removal group. The proportion of Thiobacillus denitrificans and H+ consumption showed a positive correlation with S0 accumulation. However, a very high or low ratio of H+/S0 is not suitable for S0 accumulation. The signal molecules greatly increased the concentration of protein-I and protein-II, which resulted in the high proportion of Thiobacillus denitrificans. Therefore, high S0 accumulation was achieved as Thiobacillus denitrificans regulated the H+ consumption and electron transfer rate and provided suppressed oxygen environment. This technology is cost-effective and commercially applicable for recovering S0 from wastewater.

Mechanistic insight into cost-effective dedicated oxidation of alkanes by inactivating soil organic matter with FeOOH formed in situ.

Modified Fenton technique has been widely used to remediate soils contaminated with crude oil but significantly limited to soil organic matter (SOM) consuming oxidants. In this study, soils with developed SOM inactivation by FeOOH formed in situ were created and spiked with crude oil (total petroleum hydrocarbons (TPH): 19453 mg/kg), then treated by modified Fenton reagents. The reaction activity of hydroxyl radicals (•OH) relative to TPH (K) notably increased to 0.65 when the degree of developed inactivation of the SOM (ß) was 100% (DIS-100), which was 1.45, 2.03 and 2.83-fold than that of DIS-50, DIS-15 and control (CK), respectively. Meanwhile, the higher the K, the more •OH transferred, which realized the efficient oriented oxidation of TPH. Moreover, improving the transfer of •OH from SOM to TPH was more important than increasing •OH production in soil remediation. With the ß increasing to 100%, the ratio of invalid H2O2 decomposition to produce O2 decreased to 22%, equal to 25% reduction compared to CK. Therefore, when ß was 100%, the utilization efficiency of H2O2 was improved to 1.48 mg/mmol, which was approximately 1.39, 3.35 and 5.43-fold higher than the efficiency got by DIS-50, DIS-15 and CK, respectively, achieving the cost-effective dedicated oxidation of TPH. In addition, the FeOOH cross-linked with SOM via Fe-O-C and Fe-N bonds to develop inactivation of SOM. In general, this study highlighted a new insight into the effect of developed inactivation of SOM on soil remediation.

Efficient biodegradation of chlortetracycline in high concentration from strong-acidity pharmaceutical residue with degrading fungi.

Chlortetracycline (CTC) pharmaceutical residue with strong acidity and in high CTC concentration is a hazardous solid waste. There is a huge attention but few studies on whether and how the CTC raw residue (CRR) can be degraded in microbiological way. In this study, three self-screened fungi, LJ245, LJ302 and LJ318, were used and thoroughly investigated to remove CTC, strong acidity and biotoxicity in CRR. The result disclosed that the concentration of CTC decreased rapidly in the first seven days and declined slowly subsequently, and the decreasing curve was similar to "L" shape. the corresponding degradation ratios of three strains were 95.73%, 98.53% and 98.07%, respectively. Meanwhile, numerous intermediates in degradation appeared in early days and gradually reduced, and eventually disappeared once the degradation time was long enough, among which eleven intermediates from CTC were identified. Moreover, the strong acidity of CRR declined dramatically using this biological method along with the CTC being metabolized, the pH value increased from 2.30 to 8.32 in the first 7 days. The toxicity of CRR was significantly reduced by LJ302 with inhibition rate from 96.02% to no inhibition effect to Micrococcus luteus. Therefore, CTC, strong acidity and biotoxicity of CRR could be effectively removed simultaneously through a biodegradation process driven with proposed strains.

Fast biodegradation of long-alkanes by enhancing bacteria performance rate by per-oxidation.

The long-alkanes biodegradation rate was generally found slow during widely used pre-oxidation combined with biodegradation for oil contamination treatment, resulting in long and unsustainable removal. In this study, different chitosan content was used to produce iron catalysts for pre-oxidation, and nutrients were added for the long-alkanes biodegradation experiment. Mechanism of Fenton pre-oxidation and improvement in the biodegradation rate of long-alkanes were studied by analyzing the change in organic matter and bacterial community structure, the amount and activity of bacteria in the biological stage, and the degradation amount long-alkanes hydrocarbon before and after pre-oxidation. Results showed that the destruction of bacteria greatly reduced when hydroxyl radical intensity decreased to 4.40 a.u.. Also, the proportion of humic acid-like was high (40.88%), and the community structure was slightly changed with the pre-oxidation for the fast biodegradation (FB) group. In the subsequent biodegradation, it was found that the degradation rate of each long-alkanes in the FB group increased significantly (C30: 4.18-8.32 mg/(kg·d)) with the increase of the degradation of long-alkanes (10-50%). Further studies showed that the high nutrient dynamics (6.05 mg/(kg·d)) of the FB group resulted in high bacteria performance rate (0.53 mol CO2 × log CFU/(104 g2 d)), which further accelerated the substrate transformation(41%). Therefore, the biodegradation rate of long-alkanes was increased (43.8 mg/(kg·d)) with the removal rate of long-alkanes of 76%. The half-life of long-alkanes for the FB group (64 d) was 33 d shorter than the slow biodegradation group (99 d). These results exhibited that pre-oxidation regulation can shorten the bioremediation cycle by improving the biodegradation rate of long-alkanes. This research has good engineering application value.

Stimulated biodegradation of all alkanes in soil.

This study aim to investigate the biodegradation of all alkanes in soil by adding stimulater and indigenous bacteria. The experiments were carried out by adding native bacteria and the stimulater to the soil S1 (total petroleum hydrocarbon (TPH) = 22,745 mg/kg) and soil S2 (TPH = 13,833 mg/kg) to explored the effect and mechanism of the stimulated biodegradation of all alkanes in soil. The results showed that most alkanes were used as the main carbon source of TPH in the late stimulation stage, so that all alkanes could be biodegraded by stimulating. The biodegradation of C10 - C19 (4527 mg/kg) and C20 - C30 (8530 mg/kg) were much higher than the stimulated biodegradation of partial alkanes, which indicated that the biodegradation effect of TPH was greatly improved. In addition, for the stimulated biodegradation of all alkanes group, the relative activity of TPH (TPH biodegradation/DOC consumption) was nearly 5 times that of the stimulated biodegradation of partial alkanes group in the late stimulation stage. The amount of ammonia allocated to TPH in the late stimulation stage was nearly 10 times that of DOC, and the organic matter components changed greatly in the early stimulation stage, but there was basically no change in the later stage. It showed that the hydrocarbon degraders in the stimulated biodegradation of all alkanes group used DOC as the main carbon source in the early stimulation stage and mainly degrade TPH in the later stage, which improved the biodegradation efficiency of petroleum hydrocarbons.

Synthesis of a slow-release fertilizer composite derived from waste straw that improves water retention and agricultural yield.

To enhance waste straw utilization and improve fertilizer efficiency, a novel semi-interpenetrating polymer network fertilizer (CMCK-g-PAA/PDMUP) was prepared from straw cellulose and linear polymer by solution polymerization. Polydihydroxymethyl-urea potassium phosphate (PDMUP) was included to supply nitrogen, phosphorus, and potassium nutrients. Characterization of CMCK-g-PAA/PDMUP with FTIR, XPS, XRD, and SEM techniques provided evidence for semi-interpenetrating polymer networks (semi-IPNs) and component interactions. The prepared product exhibited excellent water absorbency (681.3 g/g) and enhanced the soil's water-retention capacity. Cumulative release of N, P, and K was 56.1%, 64.3%, and 74.1%, respectively, after 40 days-meeting a Committee of European Normalization (CEN) standard. Agricultural application of CMCK-g-PAA/PDMUP promoted wheat growth. Desirable water retention, slow-release properties, and wheat growth effects highlight the product's potential for improving agriculture.

Endoplasmic reticulum stress-related neuroinflammation and neural stem cells decrease in mice exposure to paraquat.

Paraquat (PQ), a widely used herbicide, could cause neurodegenerative diseases, yet the mechanism remains incompletely understood. This study aimed to investigate the direct effect of PQ on NSC in vivo and its possible mechanism. Adult C57BL/6 mice were subcutaneously injected with 2 mg/kg PQ, 20 mg/kg PQ or vehicle control once a week for 2 weeks, and sacrificed 1 week after the last PQ injection. Furthermore, extra experiments with Tauroursodeoxycholic Acid (TUDCA) intervention were performed to observe the relationship between ER stress, neuroinflammation and the neural stem cell (NSC) impairment. The results showed that 20 mg/kg PQ caused the NSC number decrease in both subgranular zones (SGZ) and subventricular zone (SVZ). Further analysis indicated that the 20 mg/kg PQ suppressed the proliferation of NSC, without affecting the apoptosis. Moreover, 20 mg/kg PQ also induced ER stress in microglia and caused neuroinflammation in SGZ and SVZ. Interestingly, the ER stress inhibitor could simultaneously ameliorate the neuroinflammation and NSC reduction. These data suggested that increased ER stress in microglia might be a possible pathway for PQ-induced neuroinflammation and NSC impairment. That is a previously unknown mechanism for PQ neurotoxicity.

Inhibited effect of biochar application on N2O emissions is amount and time-dependent by regulating denitrification in a wheat-maize rotation system in North China.

Biochar application is considered an effective method of reducing nitrous oxide (N2O) emissions in soil. However, the mechanism and temporal effect of different doses of biochar on N2O emissions is still obscure. Here, we conducted a two-year field experiment to test the effects of different input amounts and frequencies of biochar on soil N2O emissions in North China. Biochar was applied in six different treatments in a winter wheat and summer maize rotation system: applications of 0 t/ha biochar (C0), 2.25 t/ha biochar (C1), 4.5 t/ha biochar (C2), 9 t/ha biochar (C3), and 13.5 t/ha biochar (C4) each year, and a single application of 13.5 t/ha biochar (CS) in the first year. The results showed that biochar could inhibit N2O emissions, reaching 20.6% to 60.1% in the wheat season and 18.1% to 39.4% in the maize season. The inhibitory effect of biochar on soil N2O emissions was dependent on amount and time. C3 had the best results in the wheat season, although its inhibitory effect in the maize season was not as good relative to C4 due to the lower biochar application. In addition, CS significantly reduced (27.7%) the cumulative N2O emissions in the first year, although the inhibitory effect disappeared in the second year. Biochar increased the nosZ gene copy numbers and promoted a reduction of N2O in the soil via the denitrification process. In conclusion, the inhibition of N2O emissions during denitrification is an important factor for reducing soil N2O emissions by biochar, and the inhibition of biochar is influenced by the input amount and time.

Structural and optical properties of penicillamine-protected gold nanocluster fractions separated by sequential size-selective fractionation.

Polydisperse water-soluble gold nanoclusters (AuNCs) protected by penicillamine have been synthesized in this work. The sequential size-selective precipitation (SSSP) technique has been applied for the size fractionation and purification of the monolayer-protected AuNCs. Through continuously adding acetone to a crude AuNC aqueous solution and controlling the volume percentage of acetone, we successfully separated the polydisperse AuNCs with diameters ranging from 0.5 to 5.4 nm into four different fractions sequentially. High-resolution transmission electron microscopy (HRTEM) shows that the four fractions are well-dispersed spherical particles of diameter 3.0 ± 0.6, 2.3 ± 0.5, 1.7 ± 0.4, and 1.2 ± 0.4 nm. Proton nuclear magnetic resonance spectroscopy suggests that disulfide, excess ligands and gold(I) complexes were removed from the AuNCs fractions. These results demonstrate the considerable potential of the SSSP technique for size-based separation and purification of AuNCs, achieving not only the isolation of larger nanoclusters (NCs) from small NCs in a continuous fashion, but also for the removal of small-molecule impurities. Based on the results from the mass spectrometry and thermogravimetric analysis, the average composition of the four fractions can be represented by Au38(SR)18, Au28(SR)15, Au18(SR)12, and Au11(SR)8, respectively. This indicates that the SSSP separation is mainly dependent on the core size and the ratio of Au atoms to ligands of AuNCs. X-ray photoelectron spectroscopy (XPS) has also been applied to observe the molecular dependence on the gold and sulfur chemical state of organosulfur monolayers of the fractions. The photoluminescence spectra of these AuNCs in the range of 900-790 nm was investigated at room temperature. The results show that the peak emission energy of the size-selected AuNCs undergoes a blue shift when the size is decreased, which can be attributed to the quantum confinement effect.

Developmental exposure to mercury chloride impairs social behavior in male offspring dependent on genetic background and maternal autoimmune environment.

To date, the connection between inorganic mercury (Hg) and social behavior remains incompletely understood. The aim of this study was to investigate the influence of maternal autoimmunity by inorganic Hg (Hg2+) exposure on social behavior of offspring. Wild-type (WT) and immunoglobulin deficient (Ig-/-) B10.S dams fertilized by male WT B10.S or SJL mice were treated with 50 µM Hg chloride (HgCl2). Non-pregnant female WT B10.S mice were used to investigate factors regulating HgCl2-induced autoimmunity to brain. HgCl2 selectively impaired social behavior in male offspring, but not female offspring from WT B10.S dams × male SJL, in that only male offspring displayed reduced time distribution with the stranger mouse, decreased sniffing to the stranger mouse and increased self-grooming. HgCl2 did not disrupt social behavior of male or female offspring from WT B10.S dams × male WT B10.S or Ig-/- B10.S dams × male SJL. The offspring from WT and Ig-/- B10.S dams × male SJL had equivalent autoimmunity to brain antigens during HgCl2 exposure, indicating that maternal, but not offspring-derived anti-brain antibodies (Ab) impaired social behavior of the offspring. Non-pregnant WT B10.S mice treated with HgCl2 had increased anti-brain Ab dependent on increase in CD4 T cell activation and IFNγ signaling to macrophages. IFNγ interaction with macrophages drove B cells and plasma cells to produce IgG. Therefore, HgCl2 selectively impaired social behavior in males with certain genetic background via maternally derived anti-brain Ab production, thus providing a novel insight into our current understanding of Hg toxicity.

Recent Progress on Gold-Nanocluster-Based Fluorescent Probe for Environmental Analysis and Biological Sensing.

Gold nanoclusters (AuNCs) are one of metal nanoclusters, which play a pivotal role in the recent advances in the research of fluorescent probes for their fluorescence effect. They are favored by most researchers due to their strong stability in fluorescence and adjustability in fluorescence wavelength when compared to traditional organic fluorescent dyes. In this review, we introduce various synthesis strategies of gold-nanocluster-based fluorescent probes and summarize their application for environmental analysis and biological sensing. The use of gold-nanocluster-based fluorescent probes for the analysis of heavy metals and inorganic and organic pollutants is covered in the environmental analysis while biological labeling, imaging, and detection are presented in biological sensing.

Cadmium Activates Noncanonical Wnt Signaling to Impair Hematopoietic Stem Cell Function in Mice.

Cadmium (Cd) is a toxic heavy metal that impairs the development of hematopoietic stem cells (HSCs) in mice, yet the mechanism of how Cd influences HSC remains elusive. Herein, we show that Cd activated non-canonical Wnt signaling pathway to impair HSC function in mice. After exposure to 10 ppm Cd chloride (CdCl2) via drinking water for 3 months, C57BL/6 mice displayed aberrant HSC function, in that HSC from Cd-treated mice were less efficient in rescue of lethally irradiated hosts and less competitive under mixed chimeric condition. Further analyses indicated that the small GTPase cdc42 was activated and its distribution pattern was depolarized in HSC by Cd exposure, and inhibition of cdc42 by casin, a selective chemical inhibitor, recovered the HSC capacity in rescue assay and their potential for lymphopoiesis under competitive mixed chimeric assay. Cd interaction with HSC was sufficient to promote noncanonical Wnt signaling pathway, but not canonical Wnt signaling pathway, to drive cdc42 activation and further increase the expression of C/EBPα and decrease the expression of Hhex. Moreover, Cd-induced activation of non-canonical Wnt signaling pathway in HSC did not persist long-termly in the presence of a normal niche without Cd, in that the elevated non-canonical Wnt signaling by Cd was diminished in HSC in the BM of normal recipients receiving purified HSC from Cd-treated mice after 6 months posttransplantation. Taken together, our study suggests that Cd activates cdc42 of noncanonical Wnt signaling pathway to impair HSC function, a previously unknown mechanism for Cd toxicity on HSC.

Improved crop yield and reduced nitrate nitrogen leaching with straw return in a rice-wheat rotation of Ningxia irrigation district.

Field experiments were conducted in rice-wheat rotation under conventional management to determine the effects of straw return ((half straw return, HS) and (total straw return, TS)) on crop yield, N uptake, soil properties and soil NO3--N leaching. We found that straw return significantly increased crop yield and N uptake. TS significantly increased soil SOM at depths of 20 cm and 30 cm. Straw return had significantly increased soil NO3--N leaching at a depth of 10 cm, whereas significantly decreased soil NO3--N leaching at depths of 30 cm and 90 cm in the rice season. In wheat season, HS and TS performed better than conventional fertilization management without straw return in reducing soil NO3--N leaching at depth of 90 cm. Soil NO3--N leaching was significantly decreased through enhancing total N uptake, improving soil aggregation and decreasing soil NO3--N concentration. Our results indicated that total straw return has the potential to increase crop yield, improve soil aggregation and decrease soil NO3--N concentration, thus increasing total N uptake and reducing soil NO3--N leaching in the rice-wheat rotation system of Ningxia Yellow river irrigation district. In the future, the long-term observation of crop yield and nitrate nitrogen leaching are necessary to identify the environmentally friendly straw return practices for rice-wheat rotation.

Mercury impact on hematopoietic stem cells is regulated by IFNγ-dependent bone marrow-resident macrophages in mice.

Although immunotoxic effects of mercury (Hg) have been extensively investigated, the influence of Hg on hematopoietic stem cells (HSC) remains elusive. The aim of this study was to investigate the effects of Hg on HSC. B10.S (H-2s) and DBA/2 mice (H-2d) were treated with Hg chloride (25, 50 or 100 µM HgCl2) or methyl Hg (1.25, 3.75 or 6.25 µM MeHg) via drinking water for 4 weeks, and thereafter, HSC in the bone marrow (BM) were evaluated. The number of HSC in B10.S mice was increased after treatment with 50 µM HgCl2 and decreased after treatment with 100 µM HgCl2; the number of HSC in DBA/2 mice was reduced after treatment with 50 µM HgCl2 and unaffected after treatment with 25 µM HgCl2. These effects from the HgCl2 treatments were associated with alterations of HSC proliferation, IFNγ expression and BM-resident macrophages. In vivo neutralization of IFNγ diminished the HgCl2-driven HSC proliferation, and in vivo replenishment of recombinant IFNγ eliminated the HgCl2 suppression of HSC proliferation and allowed HgCl2 enhancement of proliferation, suggesting a pivotal role of IFNγ in HSC proliferation regulated by HgCl2. In vivo depletion of macrophages and an in vitro co-culture assay indicated that BM-resident macrophages promoted HSC proliferation during HgCl2 exposure. Furthermore, the induction of BM-resident macrophages was critically dependent on IFNγ. In contrast, MeHg did not influence HSC in B10.S or DBA/2 mice. Collectively, HgCl2, but not MeHg, affects HSC through regulating IFNγ-dependent BM-resident macrophages in mice. These findings reveal a previously unknown toxicity of Hg.

Phenotypic and Functional Evaluation of Hematopoietic Stem and Progenitor Cells in Toxicology of Heavy Metals.

All blood cells are differentiated from hematopoietic stem and progenitor cells (HSPCs), a process known as hematopoiesis that can be influenced by a variety of environmental factors. In this unit, we introduce a couple of protocols including phenotypic analysis, mixed bone marrow (BM) chimera and rescue assays, colony-forming unit (CFU), and in vitro OP9 stromal cell differentiation assays for evaluating HSPCs in the BM of mice, and provide some examples of their implications in mouse models treated with heavy metals. The protocols for evaluating hematopoietic stem cells (HSCs) comprise phenotypic analysis and functional transplantation assays. The protocols for assessing hematopoietic progenitor cells (HPCs) consist of phenotypic analysis and in vitro differentiation assays. The main techniques applied in these protocols include flow cytometry (phenotypic analysis and sorting), irradiation, transplantation, and cell culture. © 2018 by John Wiley & Sons, Inc.

Effects of straw application on nitrate leaching in fields in the Yellow River irrigation zone of Ningxia, China.

A five-year field experiment was conducted to investigate the effects of straw application on nitrate leaching loss. Treatments included soil that was not treated (control), soil treated with straw at a low rate (4,500 kg ha-2, T1) and soil treated with straw at a high rate (9,000 kg ha-2, T2). Nitrate-nitrogen leaching in the 10, 20, 30, 60, and 90 cm soil layers was measured using the resin-core method. The results indicated that straw application could reduce soil nitrate leaching losses in the 0-30 cm layer. In this layer, the nitrate leaching values for T1 (13.76 kg ha-2) and T2 (13.74 kg ha-2) were both significantly lower than those of the control (15.76 kg ha-2) (P < 0.05); the soil nitrate leaching losses decreased by 12.71% and 12.84% for those two treatments, respectively. However, no significant differences in losses were observed (P > 0.05) between T1 and T2. The effects of straw application were apparent only in the ploughing layer (30 cm-depth soil layer). In the deeper layers (60 and 90 cm), no significant differences were observed between the treatments and the control, and the same results were observed in the topsoil layers (10 and 20 cm).

Effect of Nitrate Leaching Caused by Swine Manure Application in Fields of the Yellow River Irrigation Zone of Ningxia, China.

A five-year swine manure application trial and a study of nitrate leaching losses have been conducted. There were three treatments: traditional without manure (CK), traditional matched manure 4500 kg ha-2 (T1) and traditional matched manure 9000 kg ha-2 (T2). Nitrate nitrogen leaching losses at the 30-, 60-, and 90-cm soil layers were measured using the resin core method. The results indicate that the swine manure application did not noticeably increase soil nitrate leaching losses in the 30-cm layer. T1 (16.85 ± 0.40 kg ha-2) and T2 (17.01 °C0.46 kg ha-2) were not significantly different than CK (15.96 ± 0.41 kg ha-2) (P < 0.05), which was also the case at the 60-cm layer. However, there are significant differences between the treatments and CK at the 90-cm layer, although there were no significant differences between T1 and T2 in that layer. The application of manure can increase soil organic matter (SOM) and total nitrogen (TN). The SOM of T1 and T2 were increased to 0.95 g kg-1 and 1.41 g kg-1, respectively. The TN values of CK, T1 and T2 were 0.72, 0.78 and 0.88 g kg-1, respectively, in the 0 to 30 cm layer, and were improved by 7.72% and 22.04%.

Lead Transiently Promotes Granulocyte-Macrophage Progenitor Differentiation and Subsequently Suppresses Common Myeloid Progenitor Differentiation.

Lead (Pb) is a toxic heavy metal affecting human health; it is known to be harmful to various organs or systems, yet the mechanisms by which Pb influences immune cell development remain to be defined. In this study, we show that Pb exposure (1250 ppm via drinking water) selectively impacted the development of myeloid cells (myelopoiesis). After Pb treatment of adult C57BL/6 mice, the numbers of granulocyte-macrophage progenitors (GMP) were consistently reduced, whereas the numbers of myeloid cells were increased at week (wk) 1 and decreased at wk8 after initiating the Pb exposure. Functional assays indicate that Pb accelerated GMP differentiation in a reactive oxygen species-dependent manner after treatment for 1 week and inhibited common myeloid progenitor differentiation by upregulating interferon regulatory factor 8 (IRF8) expression after treatment for 8 weeks. Consistent with the distinct Pb influences on myeloid cells observed at wk1 and wk8, Pb caused an inflammatory environment in vivo at wk8, but not at wk1. Furthermore, like the observations in mice during the Pb exposure, bloods from humans occupationally exposed to Pb had their numbers of monocytes, neutrophils and GMP negatively associated with the Pb concentration, whereas IRF8 expression in common myeloid progenitor, but not GMP, was positively correlated with the Pb concentration. These data suggest an occupationally relevant level of Pb exposure preferentially influences myelopoiesis involving reactive oxygen species and IRF8, which may contribute to the current understanding of the hematopoietic toxicology of Pb.

Biochar amendment reduces paddy soil nitrogen leaching but increases net global warming potential in Ningxia irrigation, China.

The efficacy of biochar as an environmentally friendly agent for non-point source and climate change mitigation remains uncertain. Our goal was to test the impact of biochar amendment on paddy rice nitrogen (N) uptake, soil N leaching, and soil CH4 and N2O fluxes in northwest China. Biochar was applied at four rates (0, 4.5, 9 and13.5 t ha-1 yr-1). Biochar amendment significantly increased rice N uptake, soil total N concentration and the abundance of soil ammonia-oxidizing archaea (AOA), but it significantly reduced the soil NO3--N concentration and soil bulk density. Biochar significantly reduced NO3--N and NH4+-N leaching. The C2 and C3 treatments significantly increased the soil CH4 flux and reduced the soil N2O flux, leading to significantly increased net global warming potential (GWP). Soil NO3--N rather than NH4+-N was the key integrator of the soil CH4 and N2O fluxes. Our results indicate that a shift in abundance of the AOA community and increased rice N uptake are closely linked to the reduced soil NO3--N concentration under biochar amendment. Furthermore, soil NO3--N availability plays an important role in regulating soil inorganic N leaching and net GWP in rice paddies in northwest China.