Microbial functional diversity responses to 2 years since biochar application in silt-loam soils on the Loess Plateau.

The structure and function of soil microbial communities have been widely used as indicators of soil quality and fertility. The effect of biochar application on carbon sequestration has been studied, but the effect on soil microbial functional diversity has received little attention. We evaluated effects of biochar application on the functional diversities of microbes in a loam soil. The effects of biochar on microbial activities and related processes in the 0-10 and 10-20cm soil layers were determined in a two-year experiment in maize field on the Loess Plateau in China. Low-pyrolysis biochar produced from maize straw was applied into soils at rates of 0 (BC0), 10 (BC10) and 30 (BC30)tha-1. Chemical analysis indicated that the biochar did not change the pH, significantly increased the amounts of organic carbon and nitrogen, and decreased the amount of mineral nitrogen and the microbial quotient. The biochar significantly decreased average well colour development (AWCD) values in Biolog EcoPlates™ for both layers, particularly for the rate of 10tha-1. Biochar addition significantly decreased substrate richness (S) except for BC30 in the 0-10cm layer. Effects of biochar on the Shannon-Wiener index (H) and Simpson's dominance (D) were not significant, except for a significant increase in evenness index (E) in BC10 in the 10-20cm layer. A principal component analysis clearly differentiated the treatments, and microbial use of six categories of substrates significantly decreased in both layers after biochar addition, although the use of amines and amides did not differ amongst the three treatments in the deeper layer. Maize above ground dry biomass and height did not differ significantly amongst the treatments, and biochar had no significant effect on nitrogen uptake by maize seedlings. H was positively correlated with AWCD, and negatively with pH. AWCD was positively correlated with mineral N and negatively with pH. Our results indicated that shifts in soil microbial functional diversity affected by biochar were not effective indicators of soil quality in earlier maize growth periods in this region.

Development and evaluation of a rapid RPA/CRISPR-based detection of Francisella tularensis.

Francisella tularensis is a dangerous pathogen that causes an extremely contagious zoonosis in humans named tularemia. Given its low-dose morbidity, the potential to be fatal, and aerosol spread, it is regarded as a severe threat to public health. The US Centers for Disease Control and Prevention (CDC) has classified it as a category A potential agent for bioterrorism and a Tier 1 Select Agent. Herein, we combined recombinase polymerase amplification (RPA) with CRISPR/Cas12a system to select the F. tularensis target gene (TUL4), creating a two-pronged rapid and ultrasensitive diagnostic method for detecting F. tularensis. The real-time RPA (RT-RPA) assay detected F. tularensis within 10 min at a sensitivity of 5 copies/reaction, F. tularensis genomic DNA of 5 fg, and F. tularensis of 2 × 102 CFU/ml; the RPA-CRISPR/Cas12a assay detects F. tularensis within 40 min at a sensitivity of 0.5 copies/reaction, F. tularensis genomic DNA of 1 fg, and F. tularensis of 2 CFU/ml. Furthermore, the evaluation of specificity showed that both assays were highly specific to F. tularensis. More importantly, in a test of prepared simulated blood and sewage samples, the RT-RPA assay results were consistent with RT-PCR assay results, and the RPA-CRISPR/Cas12a assay could detect a minute amount of F. tularensis genomic DNA (2.5 fg). There was no nonspecific detection with blood samples and sewage samples, giving the tests a high practical application value. For example, in on-site and epidemic areas, the RT-RPA was used for rapid screening and the RPA-CRISPR/Cas12a assay was used for more accurate diagnosis.

Analysis of Gene Expression Profiles, Cytokines, and Bacterial Loads Relevant to Alcoholic Liver Disease Mice Infected With V. vulnificus.

Patients with liver disease are susceptible to infection with Vibrio vulnificus (V. vulnificus), but the specific reasons remain elusive. Through RNA-seq, we found that when mice with alcoholic liver disease (ALD) were infected with V. vulnificus by gavage, compared with the Pair group, the small intestinal genes affecting intestinal permeability were upregulated; and the number of differentially expressed genes related to immune functions (e.g., such as cell chemotaxis, leukocyte differentiation, and neutrophil degranulation) decreased in the liver, spleen, and blood. Further analysis showed that the number of white blood cells decreased in the Pair group, whereas those in the ALD mice did not change significantly. Interestingly, the blood bacterial load in the ALD mice was about 100 times higher than that of the Pair group. After the ALD mice were infected with V. vulnificus, the concentrations of T cell proliferation-promoting cytokines (IL-2, IL-23) decreased. Therefore, unlike the Pair group, ALD mice had weaker immune responses, lower T cell proliferation-promoting cytokines, and higher bacterial loads post-infection, possibly increasing their susceptibility to V. vulnificus infection. These new findings we presented here may help to advance the current understanding of the reasons why patients with liver disease are susceptible to V. vulnificus infection and provides potential targets for further investigation in the context of treatment options for V. vulnificus sepsis in liver disease patient.

[Effects of plastic film mulching and nitrogen application rate on net global warming potential in semiarid rain-fed maize cropland]. / 地膜覆盖和施氮量对旱作春玉米农田净温室效应的影响.

A one-year field experiment was conducted to evaluate the effects of plastic film mulching (FM) and nitrogen application rates applied to rain-fed maize fields on net global warming potential (Net GWP) and greenhouse gas intensity (GHGI) at the Changwu Agricultural and Ecological Experimental Station. Both GWP and GHGI were affected by the plastic film mulching and nitrogen application rate. Under the FM treatment, maize yield ranged from 1643 to 16699 kg·hm-2, the net GWP (CO2-eq) ranged from 595 to 4376 kg·hm-2·a-1, and the GHGI (CO2-eq) ranged from 213 to 358 kg·t-1. The grain yield of maize, net GWP and GHGI for the UM (no mulching) treatment were 956 to 8821 kg·hm-2, 342 to 4004 kg·hm-2·a-1 and 204 to 520 kg·t-1, respectively. The results suggested that plastic film mulching could simultaneously improve grain yield and decrease GHGI in rain-fed cropland along with nitrogen fertilizer of 250 kg·hm-2.

Tubeimoside I attenuates inflammation and oxidative damage in a mice model of PM2.5-induced pulmonary injury.

In the present study, the effects of tubeimoside I (TBMS1) on particulate matter <2.5 µm in diameter (PM2.5)-induced pulmonary injury and its mechanisms of action were investigated. Male BALB/c mice were randomly assigned into five groups (n=10/group): Control, PM2.5, PM2.5 + TBMS1 45 mg/kg, PM2.5 + TBMS1 90 mg/kg and PM2.5 + TBMS1 180 mg/kg. The dose of the PM2.5 suspension administered to the mice was 40 mg/kg via nasal instillation. The PM2.5 + TBMS1 groups received TBMS1 daily orally for 21 consecutive days, while the mice in the control and PM2.5 groups received equivalent volumes of PBS. Subsequently, lactic dehydrogenase, acid phosphatase, alkaline phosphatase, albumin, tumor necrosis factor-α and interleukin-6 protein levels in bronchoalveolar lavage fluid were determined. Oxidative stress was evaluated by detecting the protein levels of malondialdehyde, superoxide dismutase and inducible nitric oxide synthase, and the level of nitric oxide in lung tissue. Lastly, histopathological images of lung sections were obtained to observe changes in the lung tissue with treatment. The results indicated that exposure to PM2.5 induced pathological pulmonary changes, and biofilm and parenchymal cell damage, and promoted inflammation and oxidative stress. Treatment with TBMS1 attenuated the development of PM2.5-induced pulmonary injury. Its mechanisms of action were associated with reducing cytotoxic effects, levels of inflammatory mediators and oxidative damage. In conclusion, the results of the present study indicate that TBMS1 is a potential therapeutic drug for treating PM2.5-induced pulmonary injury.

High-level expression of recombinant dengue virus type 2 envelope domain III protein and induction of neutralizing antibodies in BALB/C mice.

Dengue fever is a growing public health problem in many countries since so far no effective vaccines are available. In this study, the domain III of dengue virus type 2 envelope was expressed in Escherichia coli without fusion of any carrier protein. The recombinant protein was detected in the form of inclusion bodies, which were solubilized in 8M urea and could be purified subsequently by high-performance liquid chromatography (HPLC) on an ion exchange column. After refolding, the recombinant protein inhibited the DEN-2 plaque formation on C6/36 cells, demonstrated its function of receptor-interaction was retained. The recombinant protein was inoculated into BALB/c mice to test its immunogenicity and ability to induce neutralizing antibodies. The mice immunized with the purified protein developed high antibody titers. A neutralizing titer of 1:64 was also obtained by a cytopathogenic effect (CPE) inhibition assay in C6/36 cells. Mice challenged with lethal dose of DEN-2 in combination with sera from immunized mice were protected completely. The results suggested that these expression and purification strategies have the potential for development of an inexpensive vaccine.

Effects of biochar and maize straw on the short-term carbon and nitrogen dynamics in a cultivated silty loam in China.

Application of maize straw and biochar can potentially improve soil fertility and sequester carbon (C) in the soil, but little information is available about the effects of maize straw and biochar on the mineralization of soil C and nitrogen (N). We conducted a laboratory incubation experiment with five treatments of a cultivated silty loam, biochar produced from maize straw and/or maize straw: soil only (control), soil + 1 % maize straw (S), soil + 4 % biochar (B1), soil + 4 % biochar + 1 % maize straw (B1S), and soil + 8 % biochar + 1 % maize straw (B2S). CO2 emissions, soil organic C, dissolved organic C, easily oxidized C, total N, mineral N, net N mineralization, and microbial biomass C and N of three replicates were measured periodically during the 60-day incubation using destructive sampling method. C mineralization was highest in treatment S, followed by B2S, B1S, the control, and B1. Total net CO2 emissions suggested that negative or positive priming effect may occur between the biochar and straw according to the biochar addition rate, and biochar mineralization was minimal. By day 35, maize straw, irrespective of the rate of biochar addition, significantly increased microbial biomass C and N but decreased dissolved organic N. Biochar alone, however, had no significant effect on either microbial biomass C or N but decreased dissolved organic N. Mixing the soil with biochar and/or straw significantly increased soil organic C, easily oxidized C and total N contents, and decreased dissolved organic N content. Dissolved organic C contents showed mixed results. Notably, N was immobilized in soil mixed with straw and/or biochar, but the effect was stronger for soil mixed with straw, which may cause N deficiency for plant growth. The application of biochar and maize straw can thus affect soil C and N cycles, and the appropriate proportion of biochar and maize straw need further studies to increase C sequestration.

[Effects of sensor's laying depth for precision irrigation on growth characteristics of maturate grapes].

In order to approach the appropriate laying depth of soil moisture sensor to control irrigation amount, the sensors were laid at different soil depth to measure the soil moisture content, with the effects of definite irrigation amount on the growth characteristics of maturate grapes studied. The results showed that using the sensor laying at the soil depth 40 cm (SF40) to control irrigation amount, the biological characteristics of the grapes, including photosynthesis, grape yield, and water use efficiency were superior than those when the sensor was laid at the depth 20 cm (SF20) and under conventional furrow irrigation (CK). The grape brix degree in treatment SF40 was slightly lower than that in treatments SF20 and CK, but was still near 20%. In treatment SF40, the irrigated water could infiltrate or redistribute in the soil layers where the main roots of the grapes existed. It was suggested that laying soil moisture sensor at the depth 40 cm could better control the irrigation amount for the maturate grapes in the study area.

Protective effect of a polyphenolic rich extract from Magnolia officinalis bark on influenza virus-induced pneumonia in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Magnolia officinalis bark is used in traditional Chinese medicine for the treatment of cough, colds, fever, chronic bronchitis and stomach ailments. AIM OF THE STUDY: To investigate therapeutic effects of polyphenol rich extract from M. officinalis bark (MPE) in influenza virus A-infected mice, and to provide evidence for the inflammation response and immunomodulatory potential during infection. MATERIALS AND METHODS: Mice were infected with influenza virus A (IVA) and MPE at doses of 10 and 20mg/kg were orally administrated daily for 5 days after challenge. The levels of serum L-6 and TNF-α were determined by ELISA while protein expressions of NF-κB and TLR3 were detected by western blotting analysis. RESULTS: MPE exhibited significant therapeutical effects on reducing levels of serum NO, IL-6 and TNF-α, inhibiting pneumonia, decreasing lung viral titers and sensitizing IVA-induced apoptosis through down-regulation of NF-κB and TLR3 protein expression in the lung tissue of IVA-infected mice. CONCLUSIONS: MPE could exhibit preventive and therapeutical effects on IVA-infected mice as a suppressor of the production of inflammatory mediators, NO and pro-inflammatory cytokines, TNF-α and IL-6. These effects appeared to be mediated, at least in part, by an inhibition of TLR3 and NF-κB activation. Therefore, MPE could provide a safe and effective therapeutic approach for influenza and its subsequent viral pneumonia.

Metabolites from an endophytic fungus sphaceloma sp. LN-15 isolated from the leaves of Melia azedarach.

Two new natural compounds, a symmetrical disulfide dimer didodecyl 3,3''-dithiodipropionate (1) and a pregnane steroid 5,16-pregnadien-3beta-ol-20-one acetate (2), were isolated together with two known compounds, ergosta-4,6,8(14),22-tetraen-3-one (3) and ergosterol peroxide (4), from the ethyl acetate soluble extract of fermentation broth of an endophytic fungus, Sphaceloma sp. LN-15 isolated from the leaves of Melia azedarach L. and grown in pure culture. Their structures were determined on the basis of spectroscopic methods including 1D and 2D nuclear magnetic resonance spectroscopy (NMR) experiments and by mass spectrometric measurements (MS). These fungal metabolites were isolated for the first time from the genus Sphaceloma. The structure of 1 was also confirmed by chemical synthesis.

[Utilization rate of fertilizer N and dynamic changes of soil NO3(-)-N in summer maize field in semi-humid area of Northwest China].

A field experiment on manual loessial soil was conducted to study the dynamic changes of NO3(-)-N in soil profile, utilization rate of fertilizer N, and relationships between N application rate and soil residual N accumulation during the growth period of summer maize under different N application rates (0, 45, 90, 135, and 180 kg hm(-2)). The results showed that in the whole growth period of summer maize, the NO3(-)-N concentration in the soil profile was the highest in 0-20 cm layer, and increased with increasing N application rate. The NO3(-)-N concentration in 0-60 cm soil layer changed significantly, but no significant change was observed in 60-100 cm soil layer. In the growth season of summer maize, soil NO3(-)-N accumulation presented a fluctuated decreasing trend due to the N uptake by crop and the precipitation. The N utilization rate (NUR) increased with increasing N application rate when the application rate was less than 135 kg hm(-2), but tended to decrease when the application rate exceeded 135 kg hm(-2). With the increase of N application rate, the N agronomy efficiency (NAE) decreased but the N physiology efficiency (NPE) increased. There was a significant positive correlation between soil residual N accumulation and N application rate (R2 = 0.957**, n = 5). The grain yield under N application was significantly higher than that without N application (P <0.05), and there existed a significant positive correlation between grain yield and N application rate (R2 = 0.934**, n = 5). In our experiment, the optimal application rate of fertilizer N was 135 kg hm(-2), which could harmonize the relationship between economic benefits and environment.

[Application of purified recombinant outer membrane lipoprotein LipL32 in detecting antibodies among leptospirosis cases].

OBJECTIVE: To establish recombinant outer membrane lipoprotein LipL32-based antibody detection assays in identifying leptospirosis. METHODS: Recombinant leptospiral outer membrane protein LipL32 was obtained by genetic engineering method. This purified protein was used in the indirect and sandwich ELISA assays to test the antibodies in sera of human beings and rats, and the results were compared with those obtained by microscopy agglutination test (MAT) and imported ELISA kit. RESULTS: When the acute and convalescent phase specimens from 9 leptospiral patients were tested, the detected rates of three ELISAs were similar to the MAT. Among the 45 probable cases which MAT showed positive, 32 (71.11%) samples were positive by r32-I-ELISA, 36 (80.00%) by r32-S-ELISA, while 28.89% (13/45) samples were positive and 55.56% (25/45) were suspicious by D.A.I-ELISA. The specificity of r32-I-ELISA and r32-S-ELISA were 97.10% (67/69) for 69 specimens. 43 healthy specimens were negative by both r32-I-ELISA and r32-S-ELISA, 14 healthy specimens were negative by D.A.I-ELISA. Among 16 non-leptospirosis patients, two specimens were positive by r32-I-ELISA and r32-S-ELISA, D.A.I-ELISA and identified one positive specimen, while 12 specimens were suspicious by D.A.I-ELISA. For 10 syphilis specimens, data obtained through three ELISAs were in consistent with that by MAT. A sandwiched ELISA, using rLipL32 protein as the antigen was developed to detect rat sera. Considering MAT as standard test, the sensitivity and specificity were 86.75% (131/151), 99.19% (122/123) respectively with coincidence rate as 92.34% (253/274). CONCLUSION: The recombinant protein LipL32 had high immunoreactivity and could be used as an antigen for the detection of pathogenic leptospirosis. In summary, the novel sandwiched ELISA with rLipL32 showed similar sensitivity and specificity to that of MAT in the antibody detection of rat leptospirosis. It was suitable for large scales field sero-epidemiological studies.

[Effects of spatial coupling of watering and fertilization on winter wheat photosynthetic characteristics and grain yield].

A soil column experiment was conducted with a fertile Eum-Orthic Anthrosols to study the effects of spatial coupling of watering and nitrogen (N)- and phosphorus (P) fertilization on the photosynthetic characteristics and grain yield of winter wheat. The column consisted of three layers, each layer being 30 cm in thickness and with an underlying 2 cm layer of coarse sand to obstruct water- and nutrient exchange. The results showed that relative content of chlorophyll (SPAD), net photosynthetic rate (P(n)), and grain yield were significantly lower in the treatment of 0-30 cm soil drought and 30-90 cm soil wetness (D) than in that of 0-90 cm soil wetness (W). In these two watering treatments, a combined application of N and P got the highest SPAD, P(n) and grain yield, followed by applying P, and N. The SPAD, P(n) and grain yield were significantly higher when the fertilizer N was applied in 0-90 cm layer than in 0-30, 30-60 and 60-90 cm layers, respectively. No significant differences in SPAD, P(n) and grain yield were observed when fertilizer P was applied in 0-90 cm layer and in 0-30 cm layer. In treatment W, the SPAD, P(n) and grain yield were the highest when N and P were applied in 0-90 cm layer, had no significant differences with those when the N and P were applied in 0-30 cm layer, but were significantly higher than those when the fertilization was carried out in 30-60 and 60-90 cm layers. In treatment D, no significant difference in SPAD was observed when the N and P were applied in different layers, but P(n) and grain yield were significant higher when the N and P were applied in 0-90 cm than in 30-60 cm layer, and in 30-60 cm than in 60-90 cm layer. It was concluded that whether in treatment W or in treatment D, a combined application of N and P should be carried out in 0-30 cm soil layer.

[Effects of long-term fertilization on distribution of organic nitrogen components in soil aggregates in sub-humid agroecosystem].

A 25-year long-term fertilization experiment was conducted on a Eun-Orthic Anthrosols in the sub-humid agroecosystem on Loess Plateau to study the effects of different fertilization on the distribution of organic nitrogen components in soil aggregates. The results indicated that under long-term fertilization, the distribution of hydrolyzed ammonia N and hydrolyzed unknown N (HUN) in soil aggregates was affected most significantly, followed by that of amino acid nitrogen, and of amino sugar nitrogen, suggesting that applying chemical and organic fertilizers in long-term could promote the combination of soil aggregates with hydrolyzed ammonia N and HUN, while amino sugar nitrogen was more stable during the processes of nitrogen cycling and transformation in soil. There were significant positive correlations of soil total hydrolyzed nitrogen with soil total organic carbon, total nitrogen, and fractal dimensions of aggregates, the correlation coefficient being 0.942, 0.981 and 0.910, respectively, illustrating that soil organic nitrogen components had significant effects on the formation and characteristics of soil aggregates. Correlation analysis, indicated that soil total N and organic C had greater effects on the organic nitrogen components in 1-2 mm and 0.25-1 mm soil aggregates.

[Relationships of microbial biomass carbon and nitrogen with particle composition and nitrogen mineralization potential in calcareous soil].

Taking 25 surface soil samples of calcareous soil with greater difference in fertility on Loess Plateau as test materials, this paper studied the relationships of soil microbial biomass carbon (B(C)) and nitrogen (B(N)) with soil nitrogen mineralization potential (N(0)), total nitrogen (TN), organic carbon (OC), and particle composition. The results showed that B(C) and B(N) had significant positive correlations with TN and OC, suggesting that B(C) and B(N) were highly related with soil fertility and could be used as biological indices of soil quality. B(C) and B(N) were highly correlated with N(0), with the correlation coefficient being 0.741 and 0.665, respectively (P < 0.01). B(C), B(N), TN, OC and N(0) all had significant positive correlations with physical clay (< 0.01 mm) but negative correlations with physical sand (> 0.01 mm), and had significant positive correlations with the ratio of physical clay to physical sand, indicating that soil organic matter was mainly combined with physical clay to form soil organic-mineral complexes.

[Study on the epidemiology and etiologic agent of Dengue fever outbreaks in Fuzhou in 2004].

OBJECTIVE: To study the epidemiology and etiologic characteristics of a Dengue fever outbreak in Fuzhou from the beginning of September to the end of October in 2004 in order to understand the source of infection. METHODS: Data on descriptive epidemiology was collected to study the characteristics and related factors to the epidemic. Dengue virus was isolated through the use of C6/36 cell line while viral serotypes were identified by indirect immunofluorecent assay with type-specific monoclonal antibody. The sources of infection were traced by nucleotide sequencing. RESULTS: During the epidemic, 93 cases occured consistently with the region entomoplily growth and decay. The viruses of 6 strains isolated from 10 patients' blood specimens were identified as dengue virus type 1. Phylogenetic evidence suggested that the viral isolate had high genetic relation with the isolates from Kampuchea (DENV-1/KHM/2001; GenBank Accession No. L0904278). CONCLUSION: The epidemic was caused by introduction of patients migrating into Fuzhou.