Cholinergic regulation of vascular endothelial function by human ChAT+ T cells.

Endothelial dysfunction and impaired vasodilation are linked with adverse cardiovascular events. T lymphocytes expressing choline acetyltransferase (ChAT), the enzyme catalyzing biosynthesis of the vasorelaxant acetylcholine (ACh), regulate vasodilation and are integral to the cholinergic antiinflammatory pathway in an inflammatory reflex in mice. Here, we found that human T cell ChAT mRNA expression was induced by T cell activation involving the PI3K signaling cascade. Mechanistically, we identified that ChAT mRNA expression was induced following the attenuation of RE-1 Silencing Transcription factor REST-mediated methylation of the ChAT promoter, and that ChAT mRNA expression levels were up-regulated by GATA3 in human T cells. In functional experiments, T cell-derived ACh increased endothelial nitric oxide-synthase activity, promoted vasorelaxation, and reduced vascular endothelial activation and promoted barrier integrity by a cholinergic mechanism. Further, we observed that survival in a cohort of patients with severe circulatory failure correlated with their relative frequency of ChAT +CD4+ T cells in blood. These findings on ChAT+ human T cells provide a mechanism for cholinergic immune regulation of vascular endothelial function in human inflammation.

Antidepressant-relevant concentrations of the ketamine metabolite (2R,6R)-hydroxynorketamine do not block NMDA receptor function.

Preclinical studies indicate that (2R,6R)-hydroxynorketamine (HNK) is a putative fast-acting antidepressant candidate. Although inhibition of NMDA-type glutamate receptors (NMDARs) is one mechanism proposed to underlie ketamine's antidepressant and adverse effects, the potency of (2R,6R)-HNK to inhibit NMDARs has not been established. We used a multidisciplinary approach to determine the effects of (2R,6R)-HNK on NMDAR function. Antidepressant-relevant behavioral responses and (2R,6R)-HNK levels in the extracellular compartment of the hippocampus were measured following systemic (2R,6R)-HNK administration in mice. The effects of ketamine, (2R,6R)-HNK, and, in some cases, the (2S,6S)-HNK stereoisomer were evaluated on the following: (i) NMDA-induced lethality in mice, (ii) NMDAR-mediated field excitatory postsynaptic potentials (fEPSPs) in the CA1 field of mouse hippocampal slices, (iii) NMDAR-mediated miniature excitatory postsynaptic currents (mEPSCs) and NMDA-evoked currents in CA1 pyramidal neurons of rat hippocampal slices, and (iv) recombinant NMDARs expressed in Xenopus oocytes. While a single i.p. injection of 10 mg/kg (2R,6R)-HNK exerted antidepressant-related behavioral and cellular responses in mice, the ED50 of (2R,6R)-HNK to prevent NMDA-induced lethality was found to be 228 mg/kg, compared with 6.4 mg/kg for ketamine. The 10 mg/kg (2R,6R)-HNK dose generated maximal hippocampal extracellular concentrations of ∼8 µM, which were well below concentrations required to inhibit synaptic and extrasynaptic NMDARs in vitro. (2S,6S)-HNK was more potent than (2R,6R)-HNK, but less potent than ketamine at inhibiting NMDARs. These data demonstrate the stereoselectivity of NMDAR inhibition by (2R,6R;2S,6S)-HNK and support the conclusion that direct NMDAR inhibition does not contribute to antidepressant-relevant effects of (2R,6R)-HNK.

[Currency Survey and Influencing Factors Analysis on the Knowledge and Behavior Related to Brucellosis among Occupational Workers in Jianyang City].

OBJECTIVE: To investigate the status and influencing factors of the knowledge and behavior related to brucellosis among occupational workers in Jianyang city, and to provide basic information for developing regional specific strategies for brucellosis prevention and control. METHODS: With multistage cluster random sampling, occupational workers aged ≥18 yr. who had been in contact with sheep and their products were interviewed through a questionnaire about demographic characteristic, knowledge, and behavior related to brucellosis. The knowledge and practice scores were described as frequency and percentage, and the awareness rate of knowledge about brucellosis was calculated. Unconditional logistic regression model was used to analyze the influencing factors of knowledge and behavior related to brucellosis. RESULTS: In total, 378 workers were recruited. The minority (25.1%) of the workers had heard of brucellosis, and the awareness rate of brucellosis was 22.0%. Occupational protective behaviors were poor, and the scoring rates of wearing protective clothes, mask and gloves were 58.7%, 76.5%, 71.7% respectively. The results of multivariate logistic regression analysis revealed that the awareness rate of knowledge about brucellosis decreased with age, while the low educational level was found to be associated with low awareness of knowledge about brucellosis, and occupation type had association with the awareness rate of knowledge. Besides, the awareness of knowledge about brucellosis was a protective factor and occupation type were associated with the behavior related to brucellosis. CONCLUSIONS: The knowledge and behavior related to brucellosis are poor among occupational workers in Jianyang. It is necessary to continuously implement targeted health education and health promotion programs in this region, and the people with low education level and livestock farmers should be paid special attention to.

Residue behavior and risk assessment of mixed formulation of imidacloprid and chlorfenapyr in chieh-qua under field conditions.

A simple and rapid method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the simultaneous determination of imidacloprid and chlorfenapyr residues in chieh-qua. Field trials were designed to investigate the dissipation and terminal residue behavior of the mixed formulation of imidacloprid and chlorfenapyr in chieh-qua in Guangzhou and Nanning areas. Risk assessment was performed by calculating the risk quotient (RQ) values. The developed analytical method exhibited recoveries of 89.9-110.3% with relative standard deviations (RSDs) of 2.8-12.5% at the spiked levels of 0.01, 0.10, and 1.00 mg/kg. The limit of detection (LOD) was 0.003 mg/kg, and the limit of quantification (LOQ) was 0.01 mg/kg for both imidacloprid and chlorfenapyr. It was found that the half-lives of imidacloprid in chieh-qua under field conditions were 3.3 and 3.5 days in Guangzhou and Nanning at a dose of 180 g ai/ha, while the half-lives of chlorfenapyr were 3.3 and 2.6 days, respectively. The terminal residues of imidacloprid and chlorfenapyr were from 0.01 to 0.21 mg/kg and from 0.01 to 0.46 mg/kg, respectively. Results of dietary exposure assessment showed that the RQ values were much lower than 1, indicating that the risk of imidacloprid and chlorfenapyr applied in chieh-qua was negligible to human health under recommended dosage and good agricultural practices. The proposed study would provide guidance for safe and reasonable use of imidacloprid and chlorfenapyr in chieh-qua cultivation in China.

Esmolol increases the fecal abundance of Lactobacillus in a rat model of sepsis.

BACKGROUND: Disorders of the gut microbiome could be responsible for the progression of multiple organ dysfunction syndrome. In this study, we examined the effect of esmolol on the gut microbiome in a rat model of sepsis induced by cecal ligation and puncture (CLP). METHODS: The animals (n = 32) were randomly divided into 3 groups: Sham group (sham operation + normal saline treatment, n = 8), CLP group (cecal ligation and puncture + normal saline treatment, n = 12), and CLP + ESM group (cecal ligation and puncture + esmolol treatment, n = 12). After 24 h, feces in the colon were collected for 16S rRNA gene sequencing and nitric oxide analysis. In addition, colon was removed for immunohistochemical staining of inducible nitric oxide synthase (iNOS). RESULTS: Four rats in the CLP group and two rats in the CLP + ESM group died. The abundance of Lactobacillus in the CLP + ESM group was higher than CLP group (P = 0.048). In the linear discriminant analysis effect size analysis, Norank f Muribaculaceae, Escherichia-Shigella and Lactobacillus were the predominant bacteria in the Sham group, CLP group and CLP + ESM group, respectively. The iNOS expression in colonocytes stained by brown in the CLP group were much more than Sham group (P = 0.001). Compared to CLP group, the iNOS expression in colonocytes reduced after esmolol treatment (P = 0.013). The concentration of nitric oxide in colon feces was different in Sham group, CLP group and CLP + ESM group (1.31 ± 0.15µmmol/l vs. 1.98 ± 0.27µmmol/l vs. 1.51 ± 0.14µmmol/l, P = 0.001). In addition, the concentration of nitric oxide in CLP group was higher than Sham group (P = 0.001) or CLP + ESM group (P = 0.001). CONCLUSIONS: Esmolol increased the fecal abundance of Lactobacillus in a rat model of sepsis. Moreover, esmolol reduced the iNOS expression of colonocytes and the nitric oxide concentration of colon feces.

Soil threshold values of total and available cadmium for vegetable growing based on field data in Guangdong province, South China.

BACKGROUND: Human exposure to cadmium (Cd) is largely attributed to consumption of vegetables grown in polluted soils. In China, guidelines set for Cd in soils are uniform for different crops and diverse soil types, but not risk based. A high-density sampling of 711 paired soil and vegetables was carried out across Guangdong, South China. We aimed to model the transfer of Cd from soil to leafy, rootstalk and fruit vegetables, and to set regional guidelines of Cd [total and diethylenetriaminepentaacetic acid (DTPA) -extractable] in soil for vegetable safe production. RESULTS: Both total and DTPA-extractable Cd concentrations in soil were good predictors for Cd in vegetables. The transfer of Cd in soil to vegetables could be estimated by nonlinear models, with better fit when using DTPA-extractable Cd than total Cd in soil. The calculated thresholds of soil total Cd were 2.42, 0.94 and 1.57 mg kg(-1) whereas those of soil DTPA-extractable Cd were 1.08, 0.33 and 0.63 mg kg(-1) for leafy, rootstalk and fruit vegetable fields in Guangdong, respectively, all higher than the national soil Cd threshold. CONCLUSION: Cadmium-contaminated risk for vegetable production in Guangdong province might have been over-estimated according to the Chinese Environmental Quality Standard for Soil.

[Analysis of the difference in free influenza vaccination rates between old people in urban and rural areas in Beijing].

OBJECTIVE: To assess the status of free influenza vaccination rates for the elderly in Beijing. METHODS: A questionnaire survey was carried out among 1 000 old people in Beijing. Random sampling method was employed. Descriptive analysis and Chi square test were used for statistical analysis, and Logistic regression model was used to analyze the difference in free influenza vaccination rates between the urban and rural areas. RESULTS: The continuous influenza vaccination rate of the elderly from 2007 to 2010 was 46.4%, which was higher in the rural (70.9%) than in the urban (38.3%). The vaccination rate in the rural was 3.859 times that in the urban, after other variables were controlled. CONCLUSION: The vaccination rate among the elderly in Beijing has been raised after the implementation of free influenza vaccination policy in 2007, especially for the rural people. In the urban areas, concerning about the safety of the vaccine is one of the reasons why people chose not to take free influenza vaccination; while in the rural, the insufficient knowledge about the flu and influenza vaccine plays an important role.

[Mitomycin C related complications shouldn't be neglected in the pterygium surgery].

Mitomycin C (MMC), as it could reduce tissue adhesions and scar formation, has been widely adopted in pterygium surgery to lower the recurrence rate.Upon a certain therapeutic effect obtained, a variety of ocular complications was combined and always occupies a quite long time after MMC application.once occurred, it was tough to cure. Compared to autologous limbal-conjunctival grafts, MMC has no apparent advantage to reduce reoccurrence of pterygium. Therefore, it is advised to abandon the use of MMC in pterygium surgery.

Nasal Endoscopic Incision and Drainage Transnasal Retropterygoid Approach to Upper Parapharyngeal Abscess: A Novel Technique.

Parapharyngeal infection is a well-known disease of otorhinolaryngologists. Rapid onset, short duration, severe symptoms, and manifestations such as sore throat and dysphagia are common characteristics treated primarily by surgical incision and drainage. Traditional surgical approaches encompass endoscopic transoral/nasal, transparotid, transcervical, or a combination thereof. We report a novel technique of nasal endoscopic incision and drainage transnasal retropterygoid approach to an upper parapharyngeal abscess. This report presents a case of a 14-year-old man presented with severe right neck and head pain, who was found to have an upper parapharyngeal abscess during a nasal endoscopic parapharyngeal exploration via a retropterygoid approach. The intraoperative frozen section revealed chronic mucosal inflammation and mild to moderate dysplasia of the squamous epithelium, but no carcinoma.

Decreased axonal transport rates in the Tg2576 APP transgenic mouse: improvement with the gamma-secretase inhibitor MRK-560 as detected by manganese-enhanced MRI.

Neuropil deposition of beta-amyloid (Aß) peptides is believed to be a key event in the neurodegenerative process of Alzheimer's disease (AD). An early and consistent clinical finding in AD is olfactory dysfunction with associated pathology. Interestingly, transgenic amyloid precursor protein (Tg2576) mice also show early amyloid pathology in olfactory regions. Moreover, a recent study indicates that axonal transport is compromised in the olfactory system of Tg2576 mice, as measured by manganese-enhanced magnetic resonance imaging (MEMRI). Here we tested whether the putative axonal transport deficit in the Tg2576 mouse model improves in response to a selective gamma-secretase inhibitor, N-[cis-4-[(4-chlorophenyl)-sulfonyl]-4-(2,5-difluorophenyl)cyclohexyl]-1,1,1-trifluoromethanesulfonamide (MRK-560). Tg2576 mice or wild-type (WT) littermates were treated daily with MRK-560 (30 µmol/kg) or vehicle for 4 (acute) or 29 days (chronic). The subsequent MEMRI analysis revealed a distinct axonal transport dysfunction in the Tg2576 mice compared with its littermate controls. Interestingly, the impairment of axonal transport could be fully reversed by chronic administration of MRK-560, in line with the significantly lowered levels of both soluble and insoluble forms of Aß found in the brain and olfactory bulbs (OBs) following treatment. However, no improvement of axonal transport was observed after acute treatment with MRK-560, where soluble but not insoluble forms of Aß were reduced in the brain and OBs. The present results show that axonal transport is impaired in Tg2576 mice compared with WT controls, as measured by MEMRI. Chronic treatment in vivo with a gamma-secretase inhibitor, MRK-560, significantly reduces soluble and insoluble forms of Aß, and fully reverses the axonal transport dysfunction.

An Investigation of Toxic Metal Levels (Pb, Cd, Cr, As, Hg) in Dried Porphyra and Laminaria Collected from Coastal Cities, China.

This investigation was aimed at determining the concentration levels of five toxic heavy metals (lead, cadmium, chromium, arsenic, and mercury) in dried Porphyra and Laminaria samples from coastal city of China. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for determination of lead, cadmium and total arsenic. Atomic fluorescence spectrometry was used for mercury, and liquid chromatography coupled with ICP-MS was used for arsenic speciation. The mean concentrations of lead, cadmium, chromium, total arsenic, and mercury were 0.96 ± 0.03 mg/kg, 2.62 ± 0.07 mg/kg, 1.64 ± 0.08 mg/kg, 36.67 ± 0.53 mg/kg, and 7.56 ± 0.42 µg/kg for Porphyra samples and 0.61 ± 0.03 mg/kg, 0.48 ± 0.02 mg/kg, 3.78 ± 0.56 mg/kg, 43.85 ± 1.42 mg/kg, and 46.61 ± 2.02 µg/kg for Laminaria samples. The results were comparable with previous similar research. The potential health risk assessment was conducted by comparing the calculated weekly intakes of toxic metals from Porphyra and Laminaria with provisional tolerable weekly intake. Consumption of these seaweeds does not seem to pose a risk for the consumers' health regarding their content of heavy metals. However, the potential health risk of cadmium should not be overlooked for consumers with high intake of Porphyra.

Preferential Effects of Cariprazine on Counteracting the Disruption of Social Interaction and Decrease in Extracellular Dopamine Levels Induced by the Dopamine D3 Receptor Agonist, PD-128907 in Rats: Implications for the Treatment of Negative and Depressive Symptoms of Psychiatric Disorders.

The negative and cognitive symptoms of schizophrenia and related disorders may be due to reduced dopaminergic tone in cortical brain areas. Alteration in the function of dopamine (DA) D3 receptors may play a role in this cortical hypofunctionality and underlie the deficits in social behaviors and cognitive functions in schizophrenia. Cariprazine is a potent DA D3-preferring D3/D2 receptor partial agonist that is approved for the treatment of schizophrenia and bipolar disorder. The objective of the study was to compare the abilities of cariprazine, aripiprazole (another DA receptor partial agonist with more D2 receptor preference), and ABT-925 (a selective DA D3 antagonist) to counteract the social deficit and neurochemical alterations induced by the D3 receptor-preferring agonist (+)-PD 128907 (PD) in rats. Administration of PD (0.16 mg/kg; s.c.) induced a marked (-72%) but short-lasting disruption of the defensive social aggregation behavior (huddling) in the first 10-min period. Cariprazine at all doses (0.1, 0.3, 1 mg/kg; p.o.) almost completely abolished the PD-induced disruption of huddling. Likewise, ABT-925 (3 mg/kg; p.o.) and to a lesser extent aripiprazole (20 mg/kg; p.o.) were effective in blocking the PD-induced disruption of huddling. As measured by microdialysis, the highest dose of cariprazine prevented a PD-induced decrease in DA levels (40-80 min post PD dose) in the medial prefrontal cortex (mPFC), whereas aripiprazole did not have a significant effect. ABT-925 significantly counteracted the effect of PD at 80 min post-dose. In the nucleus accumbens (nAcc) shell, the highest dose of cariprazine, as well as ABT-925 and aripiprazole, significantly reversed the PD-induced decrease in DA levels. Taken together, these data provide behavioral and in vivo neurochemical evidence for the preferential DA D3 receptor action of cariprazine in the rat. This property of cariprazine may offer therapeutic benefits against the cognitive deficits and negative/depressive symptoms of schizophrenia and related disorders.

[Response of Soil Organic Carbon Content in Different Slope Positions to Fertilization Management in Purple Soil Sloping Fields].

The purple soil sloping field is the main cultivated land type in the Three Gorges area, and the soil fertility directly determines crop yield. In order to explore the effects of different fertilization treatments on the soil organic carbon content at different slope positions, field experiments were carried out at the Three Gorges Reservoir Test Station of Chengdu Institute of Mountain and Disasters, Chinese Academy of Sciences. A total of five treatments were set up:no fertilization(CK), conventional fertilization(T1), optimum fertilization(T2), biochar combined with 85% of T2(T3), and straw combined with 85% of T2(T4), to study the differences in soil aggregate composition, soil total organic carbon, soluble organic carbon, and microbial carbon content at different slope positions under different fertilization treatments. The results showed that:①Fertilization increased the content of soil mass and improved the organic carbon content of soil, especially with T3 and T4 treatments. ②The sequence of distribution of soil organic carbon content with CK, T1, and T2 treatments in different slope positions was downslope position>middle slope position>upslope position, while the soil organic carbon content of T3 and T4 treatments was the highest at the middle slope position. ③With the decrease of slope, the soluble organic carbon content of CK, T1, T2, and T3 treated soil showed an increasing trend; the carbon content of CK, T1, T2, and T4 treated soil microorganisms increased; while the distribution of T3 treated soil microbial carbon on the slope was highest at the middle slope followed by the lower slope. In general, both biochar and straw treatments can significantly increase soil carbon content and delay the migration of soil carbon on slopes, which provides guidance for improving the soil quality and reducing water pollution of purple soil dry slopes in the Three Gorges reservoir area.

[Characteristics of Dissolved Organic Carbon Loss in Purple Soil Sloping Fields with Different Fertilization Treatments].

The characteristics of dissolved organic carbon loss with different fertilization treatments were examined to derive the best nutrient management method for sloping farmland in the Three Gorges Reservoir area where maintaining the soil carbon balance and reducing environmental pollution caused by carbon loss is crucial. Experimental runoff plots were set up at the Experimental Station for Soil and Water Conservation and Environmental Research in the Three Gorges Reservoir Region, Chinese Academy of Sciences, involving the following five treatments:No fertilization (CK), conventional fertilization (conventional), optimum fertilization (optimum), biochar combined with 85% optimum fertilizer (biochar), and straw combined with 85% optimum fertilizer (straw). The effects of the five treatments on runoff flux, sediment yield, and soil organic carbon flux were monitored and evaluated. Results show that:①Subsurface flow accounted for 52.84%-92.23% of the runoff (both surface and subsurface flow) and the loss flux of dissolved organic carbon (DOC) in the subsurface accounted for 43.64%-87.35% of the total loss flux. Thus, in this sloping farmland, subsurface flow was the main pathway of runoff and dominated dissolved organic carbon transport. ②Compared with the optimum treatment, straw treatment reduced the surface runoff flux, sediment yield, surface loss flux of DOC, and loss flux of organic carbon in the sediment by 30.39%, 39.41%, 28.71%, and 23.97%, respectively, but increased the subsurface runoff flux and loss flux of DOC. Compared with the optimum treatment, the biochar treatment significantly increased the surface and subsurface runoff flux, sediment yield, loss flux of DOC in the surface and subsurface, and the loss flux of organic carbon in the sediment. ③The loss flux of DOC accounted for 99.31%-99.94% of the loss flux of soil organic carbon, and DOC was the major species of organic carbon in the organic carbon loss in this type of sloping farmland. The loss flux of DOC under the different fertilization treatments was ranked biochar > optimum > straw > conventional > CK. ④Compared to the optimum treatment, the straw treatment and biochar treatment increased the soil organic carbon (SOC) content by 95.79% and 32.16%, respectively. Based on these results, straw combined with 85% of optimum fertilizer is the best nutrient management method for this sloping farmland as it can reduce surface runoff flux, sediment yield, and the loss flux of soil organic carbon while increasing the soil organic carbon content.

Percutaneous fixation of neonatal humeral physeal fracture: A case report and review of the literature.

BACKGROUND: Neonatal distal humeral physeal fractures are rare and difficult to diagnose. Thus, missed diagnoses and delayed healing are possible. Few studies have reported surgical treatment, because a callus may develop at the fracture site 5 d after the fracture, resulting in difficult reduction, and reduction of the limb may cause further physeal injury. Other surgical challenges include the provision of adequate anesthesia and complexity of the operation. However, without appropriate reduction and fixation, a varus elbow deformity may develop. Manual reduction and percutaneous pin fixation are ideal treatment options. CASE SUMMARY: A 4-day-old neonate with left elbow pain accompanied by limited movement for 4 d was admitted, and diagnosed with delayed physeal fracture of the distal humerus based on physical examination, ultrasonography, and magnetic resonance imaging. The patient was treated by manual reduction combined with percutaneous pin fixation under arthrography. Postoperatively, the reduction was successful. The upper limbs could have been lifted and the fingers could have been moved freely on the second day after the operation. CONCLUSION: The techniques of manual reduction and percutaneous pin fixation, to treat neonatal distal humeral physeal fractures, are safe and reliable.

[Effects of Fertilizer Reduction and Application of Organic Fertilizer on Soil Nitrogen and Phosphorus Nutrients and Crop Yield in a Purple Soil Sloping Field].

The reduction in chemical fertilizers combined with organic fertilizers is a national strategy to achieve environmental friendliness and maintain the quality of cultivated land. It is of great significance for the prevention and control of soil pollution and the sustainable development of agriculture. In this study, purple soil and sloping land in the Three Gorges Reservoir area was studied. The field experiment method was used to study the control, conventional fertilization, optimized fertilization, biochar (fertilizer combined with biochar), and straw under rapeseed/corn rotation mode. The effects of five treatments on soil nitrogen/phosphorus form, crop nitrogen and phosphorus content, fertilizer utilization rate, and crop yield were studied in the field (fertilizer reduction combined with straw returning). The results showed that the soil ammonium nitrogen content was the highest in the rapeseed season, which was 4.51 mg·kg-1. The contents of ammonium nitrogen and alkali nitrogen in the treated corn season were significantly higher than those in the rape season. The reduction in chemical fertilizers can guarantee and increase the total nitrogen content of the soil. Among them, the total nitrogen content in the rapeseed and corn seasons treated with straw was the highest (0.56 g·kg-1 and 0.60 g·kg-1, respectively). The soil treated with straw in the rapeseed season had the highest available phosphorus content (0.76 mg·kg-1). Compared with conventional treatment, the reduction of chemical fertilizers combined with organic fertilizer did not significantly reduce the total phosphorus content of soil. The reduction of fertilization combined with organic fertilizer showed a slight increase in yield but showed the highest yield of rapeseed treated by biochar (2328 kg·hm-2) and the highest yield of conventionally treated maize (5838 kg·hm-2). However, there was no significant difference in each treatment (P>0.05). Regardless of the rapeseed season or the corn season, the reduction of fertilization treatment generally improved the agronomic utilization rate of nitrogen fertilizer and phosphate fertilizer. In the purple soil area, the combination of chemical fertilizer reduction and biochar and straw returning were beneficial to improve soil nutrients, improve fertilizer utilization, and reduce the effects of nitrogen fertilizer and phosphate fertilizer application on crop yield.

[Effects of Different Forest Vegetation Types on Soil Nitrogen-Related Microbial Communities and Functions in Jinyun Mountain].

To clarify the response of a nitrogen-related microbial community and function to different vegetation types in subtropical forest, soil samples were collected for analysis from the topsoil of five vegetation types in the Jinyun Mountain National Nature Reserve, i.e., coniferous forest, broadleaf forest, mixed broadleaf-coniferous forest, P. pubescen forest, and grassland. To analyze the microbial abundance, community, and function discrepancy between different vegetation soils, multiple molecular techniques, such as terminal restriction fragment length polymorphism (T-RFLP) and quantitative polymerase chain reaction (qPCR) analysis, and nitrogen-related microbial enzyme activity procedures were used. The results showed:① The denitrifying enzyme activity was much higher than nitrifying potential in Jinyun Mountain National Nature Reserve, and the two enzyme activities were much lower in coniferous forest soil than in the other vegetation soils (P<0.05). In addition, dissolved organic carbon, soil water content, and total nitrogen were the key environmental factors controlling enzyme activity. ② The qPCR data showed that the abundance of nitrogen-related microbes was highest in P. pubescen forest, whereas it was lowest in coniferous forest. The abundances of the three nitrogen-related microbes were all significantly correlated with dissolved organic carbon, total nitrogen, available nitrogen, total potassium, and available potassium (P<0.01). ③ Based on T-RFLP data, the α-diversity of nitrogen-related microbes was highest in broadleaf forest, whereas it was lowest in P. pubescen forest. Principal co-ordinates analysis (PCoA) showed that the community structure of ammonia-oxidizing archaea responded significantly to different vegetations, and the community structure of nitrogen-related microbes showed the most difference in coniferous forest. In addition, distance-based redundancy analysis (db-RDA) showed that the community structure of nitrogen-related microbes was mainly shaped by dissolved organic carbon (P<0.001), available nitrogen (P<0.002), and soil water content (P<0.001). ④ Soil-denitrifying enzyme activity was mainly affected by the abundance of nirS-denitrifiers, ammonia-oxidizing archaea, and the community structure of nitrogen-related microbes, whereas nitrifying potential was only controlled by the abundance of ammonia-oxidizing archaea. Above all, subtropical forest vegetation significantly affects the abundance and community structure of soil nitrogen-related microbes, thereby changing their function of controlling the soil nitrogen cycle. This study can provide basic data for the coupling mechanism between soil microbes and N2O release in subtropical forests in China.

[Distribution of Organic Carbon in Soil Aggregates from Four Kinds of Forest Vegetation on Jinyun Mountain].

This study was intended to explore the distribution and stability of soil aggregates and the organic carbon for different forest types and to provide a scientific basis for the efficient management of soil carbon pools in subtropical forest ecosystems. Four subtropical forest types, including bamboo forest, broad-leaf forest, coniferous forest, and a mixed coniferous and broad-leaf forest on Jinyun Mountain (Chongqing Municipality), were selected as research subjects to explore the distribution of soil aggregates and organic carbon in different layers (depths of 0-20, 20-40, 40-60, and 60-100 cm). The results showed:The content of >2 mm aggregates and mean weight diameter (MWD), geometric mean diameter (GMD), and >0.25 mm aggregate content (R0.25) in broad-leaf forests decreased with soil depth, while other forests did not have a similar distribution pattern. In each soil layer, bamboo forest soils were mainly composed of >2 mm fractions of aggregates, which made up 30.73%-53.08% of the total content; The content of 2-0.25 mm particle size aggregates of broad-leaf and mixed forest soils was higher than that for other sizes, and its content ranged from 36.27% to 44.67% and 48.69% to 52.44%, respectively. The 2-0.25 mm and <0.053 mm fractions of aggregates dominated conifer soils. In general, the MWD, GMD, and R0.25 of bamboo aggregates were higher than for other stands in each soil layer, and the fractal dimension (D) was lower than for other stands. This indicated that the soil aggregates of bamboo forest have better stability. As the soil layer deepened, the organic carbon content of soil aggregates in forest types, except for coniferous forest, gradually decreased. Among them all, bamboo forest aggregates had the highest organic carbon content, and this was significantly higher than that of coniferous forest and mixed forest. In the whole soil profile, as far as different aggregate size is concerned, there was no obvious regularity about organic carbon in the four forest types soil aggregates; the organic carbon content of the 2-0.25 mm and <0.053 mm fractions of aggregates was high in every soil layer. There was a significant difference in the relative contribution of organic carbon in soil aggregates for different forest stands, among these contributions, the contribution rate of organic carbon in the <0.053 mm fraction of aggregates in the coniferous forest was the highest. The organic carbon contribution rate of the >2 mm fraction of bamboo forest aggregates was as high as 27.44%-53.47%. Broad-leaf forests and mixed forests had the highest contribution to the organic carbon of the 2-0.25 mm fractions of soil aggregates. Among the four forest types on Jinyun Mountain, the soil aggregates in bamboo forest have better stability, but the stability of aggregates in coniferous forests is poor. In each soil layer, the content of bamboo forest organic carbon in the various aggregates was the highest, and that of coniferous forest was the lowest.

[Effects of Land Use Type on the Content and Stability of Organic Carbon in Soil Aggregates].

The distribution and stability of soil aggregates under different land use types, and the distribution of organic carbon in various aggregates, were explored in order to provide a basis for the improvement of soil structure and the maintenance and improvement of soil organic carbon in Chongqing. Focusing on six representative subtropical land use types in the Beibei District of Chongqing (coniferous and broadleaf mixed forest, bamboo forest, orchard, dryland, paddy field, and waste grassland), soils were sorted using the wet sieving method and the six soil types were compared and analyzed. The distribution of aggregates and their organic carbon content were determined at soil profile depths of 0-20, 20-40, 40-60, and 60-100 cm for each land use type. The results showed that there were significant differences in soil structure and fertility levels under the different land use types. Among the particle size aggregates of the 0-100 cm soil layer, the aggregate particle size of the six land use types was mainly >0.25 mm; the content of >0.25 mm aggregate fraction of bamboo forest soil is the highest, followed by the grassland soil, and the dryland and orchard soils is the lowest. Granular aggregates in the size class 0.25-2 mm were mainly distributed in the 0-20 cm soil layers (28.78%-50.08%), while the aggregate size fractions 0.053-0.25 mm and<0.053 mm were mainly concentrated in the 40-60 cm soil layers. Across the entire profile depth, the aggregate MWD and GMD of the bamboo forest and barren grassland soils were higher than the other land use types, i. e., the soil aggregates in these soils were more stable. The stability of soil aggregates was significantly positively correlated with soil aggregate organic carbon content (r=0.569, P<0.01). In the 0-100 cm soil layer, the organic carbon content of soil aggregates was higher for the 0.25-2 mm and<0.053 mm fractions, with an average content of 56.54 g·kg-1 in the 0.25-2 mm fraction. Except for the organic carbon content of the soil aggregates with different particle size of dryland was the highest in the 20-40 cm soil layer, while under the other land use types, the organic carbon content in soil aggregates decreased with depth, showing significant surface enrichment. Overall, under the six different land use types, the soil aggregates in bamboo forest soils and waste grassland soils showed good stability, and at each soil depth, the organic carbon content of aggregates was highest in the bamboo forest soil.