Azospirillum isscasi sp. nov., a bacterium isolated from rhizosphere soil of rice.

A Gram-negative and rod-shaped bacterium, designated C340-1T, was isolated and screened from paddy soil in Zhongshan County, Guangxi Province, PR China. This strain grew at 20-42 °C (optimum, 37 °C), pH 5.0-9.0 (optimum, pH 7.0) and 0-4 % (w/v) NaCl (optimum, 0-1 %) on Reasoner's 2A medium. The strain could fix atmospheric nitrogen and acetylene reduction activity was recorded up to 120.26 nmol ethylene h-1 (mg protein)-1. Q-10 was the only isoprenoid quinone component; phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid and an unidentified polar lipid were the major polar lipids. Summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) were the primary cellular fatty acids. The genome of strain C340-1T was 6.18 Mb, and the G+C content was 69.0 mol%. Phylogenetic tree analysis based on 16S rRNA gene and 92 core genes showed that strain C340-1T was closely related to and clustered with the type strains Azospirillum brasilense JCM 1224T, Azospirillum argentinense Az39T, Azospirillum baldaniorum Sp245T and Azospirillum formosense JCM 17639T. The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) values between strain C340-1T and the closely related type strains mentioned above were significantly lower than the threshold values for species classification (95-96 %, 95-96 % and 70 %, respectively). Based on phylogenetic, genomic, phenotypic, physiological and biochemical data, we have reason to believe that C340-1T represents a new species of the genus Azospirillum, for which the name Azospirillum isscasi sp. nov. is proposed. The type strain is C340-1T(=CCTCC AB 2023105T=KCTC 8126T).

Inhibition of miR-495-3p ameliorated sevoflurane induced damage through BDNF/ERK/CREB signaling pathways in HT22 cells.

OBJECTIVE: Sevoflurane is used in anesthesia for surgery including in organ transplantation. We investigated the role of a non-coding single-stranded microRNA, miR-495-3p, in the sevoflurane-induced neurotoxicity using a mouse hippocampal neuronal cell line (HT22). METHODS: The levels of miR-495-3p in sevoflurane-exposed mice and HT22 cells were determined via RT-qPCR. The role of miR-495-3p on cell viability and apoptosis were determined by CCK-8 and flow cytometric assay, respectively. Western blotting was explored to measure levels of Bax, Bcl-2, active caspase 3, BDNF, p-ERK/ERK and p-CREB/CREB in HT22 cells. ELISA assay was used to examine the levels of reactive oxygen species (ROS), superoxide dismutase (SOD) and glutathione peroxidase (GPX) in cells. Dual luciferase reporter assay was used to explore the interaction of miR-495-3p and BDNF. RESULTS: The level of miR-495-3p was increased sevoflurane-exposed mice and in sevoflurane-treated HT22 cells. Downregulation of miR-495-3p inhibited sevoflurane-induced apoptosis and promoted cell proliferation by upregulating the proteins of Bcl-2 and downregulating the expressions of Bax and active caspase-3 in HT22 cells. In addition, inhibition of miR-495-3p alleviated sevoflurane-induced oxidative injuries in HT22 cells via decline of ROS and upregulation of SOD and GPX. MiR-495-3p can inhibit the ERK/CREB pathway by targeting BDNF. CONCLUSION: Downregulation of miR-495-3p can decrease oxidative status in HT22 cells and alleviate sevoflurane-induced cytotoxicity through stimulating the BDNF/ERK/CREB pathway.

Ecoenzymatic stoichiometry reveals stronger microbial carbon and nitrogen limitation in biochar amendment soils: A meta-analysis.

Soil extracellular enzyme activities of microbes to acquire carbon (C), nitrogen (N) and phosphorus (P) exert great roles on soil C sequestration and N, P availability. However, a lack of biochar-induced changes of C, N and P acquisition enzyme activities hinders us from understanding if biochar application will lead to microbial C, N and P limitation based on ecoenzymatic stoichiometry. In this study, through ecoenzymatic stoichiometry, a meta-analysis was conducted to evaluate responses of microbial metabolic limitation to biochar amendment by collecting data of ecoenzymatic activities (EEAs) of the C, N and P acquisition from peer-reviewed papers. The results showed that biochar application increased activities of C, N acquisition enzymes significantly by 9.3 % and 15.1 % on average, respectively. But the influence on P acquisition enzymes activities (Acid, neutral or alkaline phosphatase, abbreviated wholly as PHOS) was not significant. Biochar increased ratio of C acquisition enzymes activities (EC) over P enzymes activities (EP) and ratio of N enzymes activities (EN) over EP, but decreased EC:EN, indicating an increased N limitation or a shift from P limitation to N limitation in microbial metabolism. Enzyme vector analysis showed that soil microbial metabolism was limited by C relative to nutrients (N and P) under biochar amendment according to the overall increased vector length (~1.5 %). Wood biochar caused the strongest microbial C limitation, followed by crop residue biochar as indicated by increased enzyme vector length of 3.6 % and 1.2 % on average, respectively. The stronger microbial C limitation was also found when initial soil total organic carbon (SOC) was <20 g·kg-1. Our results illustrated that available nitrogen and organic carbon should be provided to meet microbial stoichiometric requirements to improve plant productivity, especially in low fertile soils under biochar amendment.

Ambient climate determines the directional trend of community stability under warming and grazing.

Changes in ecological processes over time in ambient treatments are often larger than the responses to manipulative treatments in climate change experiments. However, the impacts of human-driven environmental changes on the stability of natural grasslands have been typically assessed by comparing differences between manipulative plots and reference plots. Little is known about whether or how ambient climate regulates the effects of manipulative treatments and their underlying mechanisms. We collected two datasets, one a 36-year long-term observational dataset from 1983 to 2018, and the other a 10-year manipulative asymmetric warming and grazing experiment using infrared heaters with moderate grazing from 2006 to 2015 in an alpine meadow on the Tibetan Plateau. The 36-year observational dataset shows that there was a nonlinear response of community stability to ambient temperature with a positive relationship between them due to an increase in ambient temperature in the first 25 years and then a decrease in ambient temperature thereafter. Warming and grazing decreased community stability with experiment duration through an increase in legume cover and a decrease in species asynchrony, which was due to the decreasing background temperature through time during the 10-year experiment period. Moreover, the temperature sensitivity of community stability was higher under the ambient treatment than under the manipulative treatments. Therefore, our results suggested that ambient climate may control the directional trend of community stability while manipulative treatments may determine the temperature sensitivity of the response of community stability to climate relative to the ambient treatment. Our study emphasizes the importance of the context dependency of the response of community stability to human-driven environmental changes.

A fast chemical oxidation method for predicting the long-term mineralization of biochar in soils.

Biochar stability determines the effectiveness of biochar's functions such as carbon sequestration, soil structure improvement, soil fertility enhancement and soil pollution remediation. However, a fast method for accurately predicting biochar long-term stability in soil remains elusive. Here, firstly, an incubation experiment was conducted on mineralization dynamics of different 13C-labelled biochars over 368 days to explore their actual mineralization in soils and establish their mineralization model. Thereafter, ten treatments of fast chemical oxidation methods using K2Cr2O7 (0.1 M) with different H+ concentrations and oxidation times were applied to the biochars to reveal which method best matches the mineralization of biochar in soils. Results showed that the percentage of biochar­carbon oxidized by the solution containing 0.1 M K2Cr2O7 and 0.2 M H+ at 100 °C for 2 h was in accordance with the one that potentially would be mineralized in soils at a 100-year scale (R2 > 0.99; REMS = 2.53; RD = 15.3). The results provided a chemical oxidation method that was robust, effective, low cost and highly available for measuring the long-term stability of biochar in soils.

Distinct fungal successional trajectories following wildfire between soil horizons in a cold-temperate forest.

Soil fungi represent a major component of below-ground biodiversity that determines the succession and recovery of forests after disturbance. However, their successional trajectories and driving mechanisms following wildfire remain unclear. We examined fungal biomass, richness, composition and enzymes across three soil horizons (Oe, A1 and A2) along a near-complete fire chronosequence (1, 2, 8, 14, 30, 49 and c. 260 yr) in cold-temperate forests of the Great Khingan Mountains, China. The importance of soil properties, spatial distance and tree composition were also tested. Ectomycorrhizal fungal richness and ß-glucosidase activity were strongly reduced by burning and significantly increased with 'time since fire' in the Oe horizon but not in the mineral horizons. Time since fire and soil C : N ratio were the primary drivers of fungal composition in the Oe and A1/A2 horizons, respectively. Ectomycorrhizal fungal composition was remarkably sensitive to fire history in the Oe horizon, while saprotroph community was strongly affected by time since fire in the deeper soil horizon and this effect emerged 18 years after fire in the A2 horizon. Our study demonstrates pronounced horizon-dependent successional trajectories following wildfire and indicates interactive effects of time since fire, soil stoichiometry and spatial distance in the reassembly of below-ground fungal communities in a cold and fire-prone region.

Description of Azotobacter chroococcum subsp. isscasi subsp. nov. isolated from paddy soil and establishment of Azotobacter chroococcum subsp. chroococcum subsp. nov.

Three aerobic, asymbiotic, N2-fixing bacterial strains, designated P205T, P204 and P207, were isolated from a paddy soil in Yanting County, China. Based on 16S rRNA gene sequences, the three strains were closely related to Azotobacter chroococcum IAM 12666T (=ATCC 9043T) (99.00-99.79 % similarities). Strain P205T formed an individual branch distinct from the other two newly isolated strains and other related type strains in phylogenetic analyses based on 16S rRNA gene and 92 core genes. The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) values based on genome sequences of strain P205T and A. chroococcum ATCC 9043T, P204, P207 were near or slightly higher than the thresholds for species circumscription (95-96, 95-96 and 70 %, respectively), and the dDDH values were significantly lower than the threshold for delineating subspecies (79-80 %), which strongly supported that strain P205T belonged to A. chroococcum but was a novel subspecies distinct from the type strain of A. chroococcum. This finding was further corroborated by distinct phenotypic characteristics such as growth in Luria-Bertani (LB) medium, carbon source utilization and chemical sensitivity to vancomycin. Therefore, strain P205T represents a novel subspecies of Azotobacter chroococcum, for which the name Azotobacter chroococcum subsp. isscasi subsp. nov. is proposed with the type strain P205T (=KCTC 72233T=CGMCC 1.16846T=CCTCC AB 2019080T). The subspecies Azotobacter chroococcum subsp. chroococcum subsp. nov. is created automatically with the type strain ATCC 9043T (=DSM 2286T=JCM 20725T=JCM 21503T=LMG 8756T=NBRC 102613T=NCAIM B.01391T=NRRL B-14346T=VKM B-1616T).

Downregulated spinal IRF8 and BDNF in NAC are involved in neuropathic pain-induced depression relief via pulsed radiofrequency on dorsal root ganglion in rat SNI model.

Pulsed radiofrequency (PRF) on the dorsal root ganglion (DRG), which produces remarkable analgesia through high-frequency electromagnetic energy, has become a main therapy for chronic neuropathic pain. The chronic neuropathic pain in patients is frequently accompanied by depression. However, the underlying neurophysiological mechanisms of the treatment of PRF on DRG for the neuropathic pain-induced depression remain unclear. This study was designed to explore the effect of PRF on DRG on the neuropathic pain-induced depression in rats with spared nerve injury (SNI). Here, we found that PRF on DRG or intrathecal injection of the interferon regulatory factor 8 (IRF8) siRNA prevented the increase of mechanical allodynia and depression-like behaviors of rats after receiving SNI. Meanwhile, Western blot, immunohistochemistry, and RT-PCR revealed that PRF on DRG or intrathecal injection of IRF8 siRNA inhibited IRF8 overexpression in the spinal cord and brain-derived neurotrophic factor (BDNF) in NAc. These results suggest that neuropathic pain-induced depression could be attenuated by PRF applied to DRG in SNI rats. The suppressed overexpression of the spinal IRF8 and BDNF in NAc may play an important role and contribute considerably to effectiveness of the therapy by PRF on DRG.

Impacts of Mo application on biological nitrogen fixation and diazotrophic communities in a flooded rice-soil system.

Molybdenum (Mo) deficiency in the farmland of China may limit biological nitrogen fixation (BNF), however, the impact of Mo application on BNF capacities and diazotrophic communities in rice-soil systems is unclear. In this experiment, treatments in a 6.7 atom% 15N2-labelling field-based growth chamber for 74 days and treatments in a 99 atom% 15N2-labelling microcosm experiment for 40 days combined with 16S rRNA gene sequencing and DNA-stable isotope probing (SIP) were used to investigate the impacts of Mo application on BNF and diazotrophic communities. Our results showed that under the condition that no nitrogen (N) fertilizer was applied, Mo application (500 g sodium molybdate ha-1) significantly increased N2 fixation in a rice-Inceptisol system, from 22.3 to 53.1 kg N ha-1. Mo application significantly increased the number of nifH gene copies and the relative abundance of cyanobacteria in both growth chamber and microcosm experiments. Among cyanobacteria, the relative abundances of the most abundant genera Leptolyngbya and Microcoleus were significantly increased by Mo application. 15N2-DNA-SIP further demonstrated that Leptolyngbya and Microcoleus incorporated 15N2. Mo application greatly increased BNF in Mo-deficient paddy field (≤0.068 mg kg-1) and stimulated the growth of cyanobacteria. These results indicated that Mo application in Mo-deficient paddy field could be a useful measure to increase soil N input under no N fertilization.

Pulsed Radiofrequency on Dorsal Root Ganglion Relieved Neuropathic Pain Associated with Downregulation of the Spinal Interferon Regulatory Factor 8, Microglia, p38MAPK Expression in a CCI Rat Model.

BACKGROUND: Interferon regulatory factor 8 (IRF8), which is induced by peripheral nerve injury (PNI), plays a key role in activating spinal microglia to release inflammatory cytokines in a p38-dependent way, thereafter results in formation of central sensitization. Pulsed radiofrequency (PRF) on dorsal root ganglion (DRG) alleviates neuropathic pain and inhibits the microglial activation in chronic constriction injury (CCI) rats. However, the consequences of PRF on spinal IRF8 of CCI rats remains unknown. OBJECTIVE: We explore if PRF on DRG of rats with CCI could restrain IRF8, microglia, and p38 hyperactivity in the spinal cord to alleviate neuropathic pain. STUDY DESIGN: A randomized, controlled animal study. SETTING: Department of Pain Management, Fujian Provincial Hospital, Fujian Key Laboratory of Geriatrics, Provincial Clinic College of Fujian Medical University. METHODS: The changes in pain behaviors and the expressions of IRF8, Iba1 and p-p38 in the spinal cord of CCI rats which were administrated with antisense/ mismatch oligodeoxynucleotide of IRF8 were studied. Rats in CCI+AS ODN group, CCI+MM ODN group or CCI+NS group were intrathecally treated with antisense oligodeoxynucleotide of IRF8, mismatch oligodeoxynucleotide of IRF8 or same volume 0.9% NaCl once daily respectively, beginning from the day after nerve transection 12 hours and lasting for 7 days. The effects of PRF on L4-5 DRG of rats with CCI were investigated. PRF was applied adjacent to the L4-5 DRG at an intensity of 45 V for 6 minutes after CCI, whereas the control rats were treated without radiofrequency current. The withdrawal thresholds were studied and the spinal levels of IRF8, ionized calcium-binding adapter molecule 1 (Iba1, microglia characteristic marker) and p-p38 were calculated by ELISA, western blot, RT-PCR, and immunofluorescence. RESULTS: Intrathecal administration of antisense oligodeoxynucleotide of IRF8 led to the reversal of CCI-induced allodynia, lower activation of spinal microglia and p-p38. Withdrawal thresholds were partially recovered after a single PRF treatment for 14 days. CCI-induced IRF8 upregulation, microglia hyperactivity, and p38 phosphorylation in the spinal cord were reduced due to PRF treatment. However, PRF did not alter pain behaviors and pain signals in normal rats. LIMITATIONS: In our study, one time point was selected just to assess the levels of microglia, and p-p38. The changes of IRF8, microglia, p-p38 in the ipsilateral DRG were not investigated. A more detailed study on how PRF on the DRG could further relieve NP is needed. CONCLUSIONS: Restraining IRF8, microglia and p38 hyperactivity in the spinal cord of CCI rats involved in the contribution to the long-lasting analgesia of PRF. KEY WORDS: Neuropathic pain, pulsed radiofrequency, dorsal root ganglion, microglia, p38MAPK, Interferon regulatory factor 8, chronic constriction injury of sciatic nerve.

Methane emission by plant communities in an alpine meadow on the Qinghai-Tibetan Plateau: a new experimental study of alpine meadows and oat pasture.

Recently, plant-derived methane (CH(4)) emission has been questioned because limited evidence of the chemical mechanism has been identified to account for the process. We conducted an experiment with four treatments (i.e. winter-grazed, natural alpine meadow; naturally restored alpine meadow eight years after cultivation; oat pasture and bare soil without roots) during the growing seasons of 2007 and 2008 to examine the question of CH(4) emission by plant communities in the alpine meadow. Each treatment consumed CH(4) in closed, opaque chambers in the field, but two types of alpine meadow vegetation reduced CH(4) consumption compared with bare soil, whereas oat pasture increased consumption. This result could imply that meadow vegetation produces CH(4). However, measurements of soil temperature and water content showed significant differences between vegetated and bare soil and appeared to explain differences in CH(4) production between treatments. Our study strongly suggests that the apparent CH(4) production by vegetation, when compared with bare soil in some previous studies, might represent differences in soil temperature and water-filled pore space and not the true vegetation sources of CH(4).

[Establishment of Genic Male Sterile Lines of Brassica napus by Wide Cross and Their Cytology and Morphology.].

One and three male sterile plants were found in the progenies of the intergeneric hybrids by crossing Brassica napus and Brassica juncea to Orychophragmus violaceus, respectively. After interspecific cross and full-sib crosses, four genic male sterile lines were obtained. The results of cytological observations indicated that somatic chromosome number was 38 in all types of sterile lines, which were considered as the type of B. napus. Most of pollen mother cells (PMC) in all sterile plants were observed normally for chromosome behaviour. But abnormal phenomena of chromosome, which present for chromosome lagging and bridge, were still found at each stage of meiosis in these sterile lines. These lines belonged to complete sterile type. There were distinct differences between sterile plants and normal plants in the flower morphology. Bud death at different degrees was found on anthotaxies in sterile plants. Studies on the flower growth showed that the growths of the pistils in sterile plants were gradually accelerated along with pollen sterility. At the same time there were two slowly growth stages of the pistils growth in normal plants. The prospects of these sterile lines were discussed in this paper.

[Hypoploid groups and their cytogenetic analysis in the progenies between Brassica napus and Orychophragmus violaceus].

Several groups of hypoploids were characterized in pentaploid (p) progenies of B. napus and O. violaceus. Cytological characterization of the P3 population revealed allosubstitution of one pair of B. napus chromosomes with O. violaceus chromosomes. This population had normal fertility and had three kinds of somatic cells with 36-38 chromosomes. Its somatic cells and pollen mother cells (PMC) mainly had 38 chromosomes. From a P4 population, three monosomic plants with 37 chromosomes were identified with differing morphology and fertility. One plant which grew vigorously was composed of various types of somatic cell and PMC, in which the cells with 37 chromosomes were observed mainly. The unpaired chromosome was small and with no negative effects on plant development. In the offsprings of the aneuploids (P3) with 41-44 chromosomes, there are four types of plants with 29-32 chromosomes. Except the plant with 29 chromosomes, others which appeared abnormal meiosis behavior and poor pollen fertility are mixoploid. The origin of these hypoploids and their prospects of application have been discussed.