Differential salt stress resistance in male and female Salix linearistipularis plants: insights from transcriptome profiling and the identification of the 4-hydroxy-tetrahydrodipicolinate synthase gene.

MAIN CONCLUSION: Lysine plays an essential role in the growth differences between male and female S. linearistipularis plants under salt stress. Furthermore, SlDHDPS is identified as a vital gene contributing to the differences in saline-alkali tolerance between male and female plants of S. linearistipularis. Soil salinization is a significant problem that severely restricts agricultural production worldwide. High salinity and low nutrient concentrations consequently prevent the growth of most plant species. Salix linearistipularis is the only woody plant (shrub) naturally distributed in the saline-alkali lands of the Songnen Plain in Northeast China, and it is one of the few plants capable of thriving in soils with extremely high salt and alkaline pH (>9.0) levels. However, insufficient attention has been given to the interplay between salt and nitrogen in the growth and development of S. linearistipularis. Here, the male and female plants of S. linearistipularis were subjected to salt stress with nitrogen-starvation or nitrogen-supplement treatments, and it was found that nitrogen significantly affects the difference in salt tolerance between male and female plants, with nitrogen-starvation significantly enhancing the salt stress tolerance of female plants compared to male plants. Transcriptional analyses showed 66 differentially expressed nitrogen-responsive genes in female and male roots, with most of them showing sexual differences in expression patterns under salinity stress. RNA-seq and RT-qPCR analysis demonstrated that six genes had an opposite salt-induced expression pattern in female and male roots. The expression of the 4-hydroxy-tetrahydrodipicolinate synthase encoding gene (SlDHDPS) in female roots was higher than that in male roots. Further treatment with exogenous lysine could significantly alleviate the inhibitory effect of salt stress on the growth of female and male plants. These results indicate that the SlDHDPS in the nitrogen metabolism pathway is involved in the resistance of S. linearistipularis to salt stress, which lays a foundation for further exploring the mechanism of nitrogen on salt tolerance of S. linearistipularis, and has a significant reference value for saline-alkali land management and sustainable agricultural development.

Genome-wide identification and expression analysis of Ubiquitin-specific protease gene family in maize (Zea mays L.).

BACKGROUND: Ubiquitin-specific proteases (UBPs) are a large family of deubiquitinating enzymes (DUBs). They are widespread in plants and are critical for plant growth, development, and response to external stresses. However, there are few studies on the functional characteristics of the UBP gene family in the important staple crop, maize (Zea mays L.). RESULTS: In this study, we performed a bioinformatic analysis of the entire maize genome and identified 45 UBP genes. Phylogenetic analysis indicated that 45 ZmUBP genes can be divided into 15 subfamilies. Analysis of evolutionary patterns and divergence levels indicated that ZmUBP genes were present before the isolation of dicotyledons, were highly conserved and subjected to purifying selection during evolution. Most ZmUBP genes exhibited different expression levels in different tissues and developmental stages. Based on transcriptome data and promoter element analysis, we selected eight ZmUBP genes whose promoters contained a large number of plant hormones and stress response elements and were up-regulated under different abiotic stresses for RT-qPCR analysis, results showed that these genes responded to abiotic stresses and phytohormones to varying degrees, indicating that they play important roles in plant growth and stress response. CONCLUSIONS: In this study, the structure, location and evolutionary relationship of maize UBP gene family members were analyzed for the first time, and the ZmUBP genes that may be involved in stress response and plant growth were identified by combining promoter element analysis, transcriptome data and RT-qPCR analysis. This study informs research on the involvement of maize deubiquitination in stress response.

Effect of nitrilotriacetic acid and tea saponin on the phytoremediation of Ni by Sudan grass (Sorghum sudanense (Piper) Stapf.) in Ni-pyrene contaminated soil.

Phytoremediation is commonly used in the remediation of soils co-contaminated by heavy metals and polycyclic aromatic hydrocarbons (PAHs) because of its economy and effectiveness. Sudan grass (Sorghum sudanense (Piper) Stapf.) has well-developed roots and strong tolerance to heavy metals, so it has been widely concerned. In this study, nitrilotriacetic acid (NTA) and tea saponin (TS) were used as enhancers and combined with Sudan grass for improving the remediation efficiency of Ni-pyrene co-contaminated soil. The results of the pot experiment in soils showed that enhancers promoted the enrichment of Ni in plants. With the function of enhancers, more inorganic and water-soluble Ni were converted into low-toxic phosphate-bonded and residual Ni, so as to reinforce the tolerance of Sudan grass to Ni. In the pot experiment based on vermiculite, it was found that enhancers increased the accumulation of Ni in cell wall by 49.71-102.73%. Enhancers also had the positive effect on the relative abundance of Proteobacteria, Patescibacteria and Bacteroidetes that could tolerate heavy metals at phylum level. Simultaneously, the study found that pyrene reduced the exchangeable Ni in soils. More Ni entered the organelles and transfer to more high-toxic forms in Sudan grass when pynere coexisted. The study manifested that enhancers improved the phytoremediation effect of Ni significantly, yet the co-existence of pyrene weakened the process. Our results provided meaningful references for remediating actual co-contaminated soil of heavy metals and PAHs.

Household concentrations and personal exposure of PM2.5 among urban residents using different cooking fuels.

Exposure to PM2.5 is a leading environmental risk factor for many diseases and premature deaths, arousing growing public concerns. In this study, indoor and outdoor PM2.5 concentrations were investigated during the heating and non-heating seasons in an urban area in northwest China. Personal inhalation exposure levels among different age groups were evaluated, and the difference attributable to different cooking fuels including coal, gas and electricity, was discussed. The average concentrations of PM2.5 in the kitchen and the bedroom were 125±51 and 119±64µg/m(3) during the heating season, and 80±67 and 80±50µg/m(3) during the non-heating season, respectively. Indoor PM2.5, from indoor combustion sources but also outdoor penetration, contributed to about 75% of the total PM2.5 exposure. Much higher indoor concentrations and inhalation exposure levels were found in households using coal for cooking compared to those using gas and electricity. Changing from coal to gas or electricity for cooking could result in a reduction of PM2.5 in the kitchen by 40-70% and consequently lower inhalation exposure levels, especially for children and women.

Health risk assessment of various metal(loid)s via multiple exposure pathways on children living near a typical lead-acid battery plant, China.

Manufacture of lead-acid batteries is of widespread interest because of its emissions of heavy metals and metalloids into environment, harming environmental quality and consequently causing detrimental effects on human health. In this study, exposure pathways and health risks of children to heavy metal(loid)s (Pb, Cd, As, etc) were investigated based on field sampling and questionnaire. Pb was one of the most abundant elements in children's blood, with an elevated blood lead level of 12.45 µg dL(-1). Soil/dust and food were heavily polluted by targeted metal(loid)s. Food ingestion accounted for more than 80% of the total exposure for most metal(loid)s. The non-cancer risks to children were 3-10 times higher than the acceptable level of 1, while the cancer risks were 5-200 times higher than the maximum acceptable level of 1.0 × 10(-4). The study emphasized the significance of effective environmental management, particularly to ensure food security near battery facilities.

Levels and source apportionment of children's lead exposure: could urinary lead be used to identify the levels and sources of children's lead pollution?

As a highly toxic heavy metal, the pollution and exposure risks of lead are of widespread concern for human health. However, the collection of blood samples for use as an indicator of lead pollution is not always feasible in most cohort or longitudinal studies, especially those involving children health. To evaluate the potential use of urinary lead as an indicator of exposure levels and source apportionment, accompanying with environmental media samples, lead concentrations and isotopic measurements (expressed as (207)Pb/(206)Pb, (208)Pb/(206)Pb and (204)Pb/(206)Pb) were investigated and compared between blood and urine from children living in the vicinities of a typical coking plant and lead-acid battery factory. The results showed urinary lead might not be a preferable proxy for estimating blood lead levels. Fortunately, urinary lead isotopic measurements could be used as an alternative for identifying the sources of children's lead exposure, which coincided well with the blood lead isotope ratio analysis.

Isotopic ratio based source apportionment of children's blood lead around coking plant area.

Lead exposure in the environment is a major hazard affecting human health, particularly for children. The blood lead levels in the local children living around the largest coking area in China were measured, and the source of blood lead and the main pathways of lead exposure were investigated based on lead isotopic ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) in blood and in a variety of media, including food, airborne particulate matter, soil, dust and drinking water. The children's blood lead level was 5.25 (1.59 to 34.36 as range) µg dL(-1), lower than the threshold in the current criteria of China defined by the US Centers for Disease Control (10 µg dL(-1)). The isotopic ratios in the blood were 2.111±0.018 for (208)Pb/(206)Pb and 0.864±0.005 for (207)Pb/(206)Pb, similar to those of vegetables, wheat, drinking water, airborne particulate matter, but different from those of vehicle emission and soil/dust, suggesting that the formers were the main pathway of lead exposure among the children. The exposure pathway analysis based on the isotopic ratios and the human health risk assessment showed that dietary intake of food and drinking water contributed 93.67% of total exposed lead. The study further indicated that the coal used in the coking plant is the dominant pollution source of lead in children's blood.

[Effect of leptin on lung fibrosis of silicosis rats and the correlation between leptin and HIF-1α expressions].

OBJECTIVE: To observe the expression of leptin (LP) and its influence on pulmonary fibrosis in experimental rats with silicosis and the correlation between the expressions of leptin and HIF-1α. METHODS: A total of 120 male Sprague-Dawley rats were randomly divided into normal control group, silicosis model group, LP intervention groups (consisting of LP5, LP10 and LP20 groups according to the concentration of LP). The rats in the normal control group were intratracheally administered 1 mL normal sodium, and the ones in the other groups were intratracheally given 1 mL SiO2(40 mg/mL) suspension. The rats in LP intervention groups were intraperitoneally injected with leptin 5, 10, 20 ng/kg.d respectively from the first day. Six rats in each group were sacrificed on the 7th, 14th, 21th and 28th day. The expression of LP on the 7th, 14th, 21th and 28th day and the hydroxyproline content on the 28th day in rat lung tissues were measured by ELISA, and the expressions of HIF-1α and LP proteins in the lung tissues of the silicosis model group were measured by Western blotting. RESULTS: There were significant differences in the expression of LP in the lung tissues at each time point (7th, 14th, 21th and 28th day) among the five groups (F=669.18, 948.67, 1 172.00, 521.55, P<0.05). The LP content in the silicosis model group was significantly higher than that in the normal control group (P<0.05) and the expression of LP in the LP intervention groups were significantly elevated at each time point (P<0.05) as compared with the silicosis model group. Hydroxyproline content on 28th day was (0.89 ± 0.16), (3.14 ± 0.40), (3.78 ± 0.27), (4.35 ± 0.13), (4.87 ± 0.16) mg/g in normal control group, silicosis model group, LP5, LP10 and LP20 intervention groups, respectively. Compared with the normal control group, hydroxyproline content in the silicosis model group significantly increased (P<0.05), and compared with the silicosis model group, hydroxyproline content in LP intervention groups were significantly raised (P<0.05). The significant positive correlations were noted between the expressions of HIF-1α and LP (r=0.876, 0.796, 0.859 and 0.854 at each time, P<0.05). CONCLUSION: The expression of LP goes up significantly in the lung tissues of rats with silicosis. Addition of exogenous leptin can increase the collagen deposition in the lung tissues; meanwhile leptin has a positive correlation with HIF-1α.