Search

Purpose: The increasing soil microplastics (MPs) pollution and the dry–wet alternation caused by climate change occur widely. Emerging studies have shown their negative impacts on the structure of soil bacteria and plant physiology. However, there is limited research on the effects of MPs exposure under different water regimes, and the influence processes are inconclusive. Therefore, the impacts of MPs under different water regimes on the antioxidant activity of vegetable and the soil bacterial community were studied. Materials and methods: A continuous water supply and a dry–wet cycle were established to compare the effects of two types of MPs (polypropylene (PP); polyethylene terephthalate (PET)) on lettuce (Lactuca sativa L. var. longifolia) growth and soil bacterial community, determined by antioxidant enzyme activity analysis, and by high-throughput sequencing analysis, respectively. Results: The PET influenced the lettuce growth and bacterial diversity largely compared to PP. The dry–wet cycle enhanced the effects of MPs on the activity of the antioxidant enzymes in lettuce, while it reduced lettuce biomass and root activity. Proteobacteria and Actinobacteria were the dominant soil bacteria under all treatments. The addition of MPs increased the relative abundance of nutrient-related bacteria such as Proteobacteria. MPs addition increased intragroup differences in soil bacterial diversity, and the dry–wet cycle reduced intergroup differences caused by MPs. Conclusion: The polymer type of MPs influenced the antioxidant activity of lettuce roots and leaves. The dry–wet cycle intensified the exposure risk of MPs by enhancing the stimulation of MPs on the antioxidant activity of lettuce. The dry–wet cycle significantly reduced the MPs-induced differences in bacterial communities. In short, the dry–wet cycle might alter the ecological risks in plant-soil ecosystem by shifting soil bacterial lineages related to nutrient cycling and metabolic function under MPs exposure. [ABSTRACT FROM AUTHOR]

Premature ejaculation (PE) is a common male sexual dysfunction disorder, and is considered to have the genetic predisposition. However, the internal regulation mechanisms is still unclear. Hence, this study intended to explore the effects of genetic polymorphisms of CYP24A1 on the risk of PE. This case–control study genotyped three SNPs of CYP24A1 (rs2762934, rs1570669 and rs6068816) from 139 PE patients and 372 healthy men using Agena MassARRAY platform. Collected data was then processed in SPSS 18.0. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in logistic regression analysis to evaluate the associations between CYP24A1 polymorphisms and the PE risk. The results suggested that allele A of rs1570669 was significantly associated with the increased PE risk (OR=1.38, 95% CI=1.04–1.84, P=0.026). Meanwhile, we also identified rs1570669 as a risk factor of PE under the additive model (OR=1.47, 95% CI=1.02–2.11, P=0.039) by comparing the genotypic distributions between cases and controls, and genotype AA of rs1570669 was detected to be significantly related with an increased risk of PE under the codominant model (OR=2.26, 95% CI=1.06–4.83, P=0.036). This study is the first to proved that the genetic variants of CYP24A1 played essential role in affecting the susceptibility to PE in Chinese Han. [ABSTRACT FROM AUTHOR]

Ecological stoichiometry is essential for understanding the biogeochemical cycle in forest ecosystems. However, previous studies of ecological stoichiometry have rarely considered the impacts of forest origins, which could help explain why to date so much uncertainty has been reported on this subject. In this study, we tried to reduce this uncertainty by examining carbon (C), nitrogen (N) and phosphorus (P) in roots, litter and soil in both natural and plantation forests throughout China. The sampled forest sites were divided into three groups according to the identified succession stages: early (ES), middle (MS) and late (LS) stages. Our results show that soil C, N and P concentrations were significantly higher in natural (NF) than in plantation (PL) forests. As succession/growth proceeded, P concentrations significantly increased in litter, roots and soil in NF, while the opposite occurred in PL. These results indicate that NF are able to use P more efficiently than PL, especially in the LS. Furthermore, the higher root N:P ratio indicates that the growth of PL was limited by P in both MS and LS. Our results also suggest that geographical and climatic factors are not the dominant factors in the differences in P between NF and PL, and, even more clearly and importantly, that native forests with native species are more capable of conserving P than planted forests, which are frequently less diverse and dominated by fast-growing non-site native species. These results will help improve biogeochemical models and forest management throughout the world. [ABSTRACT FROM AUTHOR]

Soil phosphorus (P) loss risk and environmental impact can be assessed by different soil test indicators such as soil P storage capacity (SPSC), a site-specific and reliable measurement of soil P status. In this study, the changing trends of soil P saturation ratio (PSR) and SPSC in red soil (equivalent to Ultisol) were discussed after 10 consecutive additions of P solution with 20 mg P L−1, and the relationships between Olsen-P, CaCl2-P, and PSR, SPSC also were evaluated. Results showed that the soil PSR was increased to 0.22 at the end of P addition, and the accumulated P was high to 1625 mg kg−1. The threshold PSR of the red soil was determined to be 0.10, and the SPSC significantly decreased from 242.0 mg kg−1 to −382.1 mg kg−1 with the increase of P addition times. When SPSC = 0, the accumulated P in red soil was 487.7 mg kg−1. Therefore, there existed four stages for the soil P management in red soil according to the changes of SPSC and Olsen-P: short supply stage of soil P (SPSC>88 mg kg−1 and Olsen-P ≤ 20 mg kg−1), stable supply stage of soil P (68 mg kg−1< SPSC≤88 mg kg−1 and 20 mg kg−1< Olsen-P ≤ 40 mg kg−1); over supply stage of soil P (0< SPSC≤68 mg kg−1 and 40 mg kg−1< Olsen-P ≤ 108 mg kg−1), and the high loss risk stage of soil P (SPSC≤0 and Olsen-P > 108 mg kg−1). In the last stage, P fertilization must be stopped and environmental protection measures must be taken immediately. [ABSTRACT FROM AUTHOR]

Purpose: Elevated CO2 concentration (eCO2) may stimulate plant growth and influence the soil microbial community, but questions remain for whether microbial responses to elevated CO2 would vary by different CO2-responsive plants. We thus attempted to elaborate the changes of soil microbiome to different rice cultivars under the eCO2 condition. Materials and methods: Two rice cultivars, i.e., the CO2-tolerant cultivar, Wuyunjing23 (WYJ23), and the CO2-sensitive one, Yandao 6 (YD6), were grown under eCO2 and ambient CO2 (aCO2) conditions. The contents of dissolved organic carbon (DOC) and nitrogen (DON) in soil were measured. Real-time qualitative PCR (qPCR) and high-throughput sequencing techniques were employed to characterize the bacterial community. Furthermore, co-occurrence network analysis was applied to reveal the ecological interactions among bacterial taxa. Results and discussion: No significant differences were found among all treatments in terms of bacterial population, alpha-diversity indices, and bacterial community structure. However, the topological parameters of ecological networks highlighted the distinct co-occurrence patterns among treatments. YD6 under eCO2 led to more links, lower modularity, and greater centralization degree compared to that under aCO2. Opposite trends of those parameters were observed for WYJ23 under eCO2 compared to that under aCO2. Besides, more Proteobacteria and Acidobacteria served as keystone taxa in the CO2-sensitive cultivar treatments, compared to those in WYJ23, implying the different influences of rice cultivars on the microbial ecological network. Conclusions: Different rice cultivars under eCO2 did not influence the alpha- and beta-diversity of the soil bacterial community, but changed the co-occurrence network of the community. More attention should be paid to the assembly mechanisms of the soil microbial microbiome when evaluating the impacts of productive crops on the soil-plant ecosystem under the eCO2 condition. [ABSTRACT FROM AUTHOR]

Microcalorimetry and BIOLOG are common tools in the study of soil microbial metabolism. When used combined, they may reveal further details about soil microbial metabolic diversity than individually. Through this study, we demonstrated the advantages of such a combinatorial methodology by comparing soil samples from two locations in China, each with (OM samples) and without (control) organic fertilization. We used BIOLOG and microcalorimetry to study soil microbes' ability to metabolize different C substrates. Microcalorimetric measurements helped us further reveal the differences in the microbial growth kinetics under different BIOLOG-identified C substrates. Results showed that soils differed in the preferred C substrates, as denoted by the thermodynamic parameters. Some C substrates stimulated the active microbial biomass, while some stimulated microbial growth rate. Most interestingly, certain C substrates (e.g., l-arginine for Shandong soil and glycogen for Henan soil) showed stimulating effects on both OM and control soils, which could be attributed to the pH value and P availability in soil. Hence, we believe microcalorimetry could be potentially used to explore the soil microbial metabolic diversity by combining BIOLOG measurement, especially in determining how microbes assimilate different nutrient sources. [ABSTRACT FROM AUTHOR]

Purpose: The extract of Stevia residue is an ideal substitute for cultivation of the purple nonsulfur bacterium, like Rhodopseudomonas palustris ( R. palustris). But the influence of R. palustris grown under residue extract on its downstream application is still not well-characterized. The objective of this study was to assess the effect of foliar spray of R. palustris grown under Stevia residue extract on the plant growth and soil microbial properties. Materials and methods: A pot experiment was carried out under the greenhouse condition, consisting of four treatments varying in the sprayed substances: sterilized water (control), R. palustris grown under the chemical medium supplemented with L-tryptophan (SyT), R. palustris grown under Stevia residue extract supplemented with L-tryptophan (ExT), and R. palustris grown under Stevia residue extract supplemented with NHCl (ExT). The net photosynthesis rate of the uppermost leaves was measured with a portable photosynthesis system. Soil microbial activity was analyzed by microcalorimetry. Soil bacterial community components were determined by real-time quantitative PCR (qPCR) and high-throughput sequencing techniques. Results and discussion: Compared with SyT, the R. palustris grown under Stevia residue extract not only improved the plant biomass and the net photosynthetic rate to a large extent, but also increased soil microbial metabolic activity and altered community compositions as well. The treatments receiving R. palustris, especially ExT and ExN, increased the relative abundances of some functional guilds involved in C turnover and nutrient cycling in soil, including Acidobacteria, Actinobacteria, Proteobacteria, Gemmatimonadaetes, Nitrospirae, and Planctomycetes. Conclusions: R. palustris grown under the Stevia residue extract showed advantages over that under the chemical medium on both plant growth and soil microbial properties. One of the possible reasons could result from the increases in microbial activity and several bacterial keystone guilds involved into C and nutrient cycling, both of which potentially contribute to the improved plant growth. The results would be conducive to the downstream application of R. palustris in an economical way. [ABSTRACT FROM AUTHOR]

The interaction between cancer and its microenvironment is crucial for survival and development of cancerous cells. Tumor microenvironment is usually under hypoxia, which promotes tumor aggressiveness like growth, angiogenesis, and metastasis. How cancer cells respond to hypoxia and the resultant impact on tumorigenesis are not yet fully explored. Long noncoding RNAs (lncRNAs) have been attracting more and more attention since their functions in regulating gene expression at chromatic, transcriptional, and posttranscriptional levels were found. lncRNAs are dysregulated in cancer and act as oncogenes or tumor suppressors. Moreover, emerging evidence has been provided that the expression of lncRNAs changes with the stimulus of hypoxia and they in turn produce a significant influence on the hypoxia-inducible factor (HIF), the most common transcription regulator in response to hypoxia. In this review, we discuss the recent findings of hypoxia-responsive lncRNAs and summarize their interaction with hypoxia to further understand their roles in cancer growth, metabolism, angiogenesis, and metastasis and their potential for cancer diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Due to the ever-increasing worldwide plantation of sweet leaf Stevia rebaudiana (Bertoni), how to efficiently and effectively utilize the huge amounts of leaf residues that contain abundant nutrients after sweetener extraction becomes an eminent issue. One option is to return these residues into soil, as organic manure in the fresh or composted form, in order to both sustain soil fertility and avoid potential environmental pollution. In a field experiment, we studied if the Stevia leaf residue returning affected both plant and soil microbial growths as well as the possible change of soil microbial community composition. In doing so, four treatments were employed: (1) no chemical fertilization and no Stevia residue returning (no-fertilization control); (2) chemical N, P, and K fertilization (NPK); (3) fresh Stevia residue plus NPK (FS + NPK); and (4) composted Stevia residue plus NPK (CS + NPK). Responses of plant and soil microbial communities to Stevia residue input after 1-year fertilizations were investigated by multiple approaches, including soil enzyme assay, real-time quantitative polymerase chain reaction, and PCR-denaturing gradient gel electrophoresis. Our results showed that compared to the sole NPK and no-fertilization control, returning Stevia residues to soil stimulated the enzyme activities of dehydrogenase, invertase, and urease, except neutral phosphomonoesterase; thereby, both the Stevia leaf biomass and sweet glycoside of rebaudioside A were increased. The soil microbial community abundance was increased by the returning of Stevia residues, and their composition was shifted, evidenced by an increase of relative abundance of some genotypic groups, such as Bacillales. Further molecular analysis of Bacillus confirmed that this guild composition was positively influenced by Stevia residue returning, especially for Bacillaceae. Our results demonstrated an effective use of Stevia residues as organic manure for promoting Stevia yield and quality through stimulating soil microbial growth and enzyme activities. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM2.5) is a typical air pollutant and has adverse health effects across the world, especially in the rapidly developing China due to significant air pollution. The PM2.5 pollution varies with time and space, and is dominated by the locations owing to the differences in geographical conditions including topography and meteorology, the land use and the characteristics of urbanization and industrialization, all of which control the pollution formation by influencing the various sources and transport of PM2.5. To characterize these parameters and mechanisms, the 5-year PM2.5 pollution patterns of Jiangsu province in eastern China with high-resolution was investigated. The Kriging interpolation method of geostatistical analysis (GIS) and the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model were conducted to study the spatial and temporal distribution of air pollution at 110 sites from national air quality monitoring network covering 13 cities. The PM2.5 pollution of the studied region was obvious, although the annual average concentration decreased from previous 72 to recent 50 μg m−3. Evident temporal variations showed high PM2.5 level in winter and low in summer. Spatially, PM2.5 level was higher in northern (inland, heavy industry) than that in eastern (costal, plain) regions. Industrial sources contributed highest to the air pollution. Backward trajectory clustering and potential source contribution factor (PSCF) analysis indicated that the typical monsoon climate played an important role in the aerosol transport. In summer, the air mass in Jiangsu was mainly affected by the updraft from near region, which accounted for about 60% of the total number of trajectories, while in winter, the long-distance transport from the northwest had a significant impact on air pollution. [ABSTRACT FROM AUTHOR]