Environmental and management controls of soil carbon storage in grasslands of southwestern China.

In order to predict the effects of climate change on the global carbon cycle, it is crucial to understand the environmental factors that affect soil carbon storage in grasslands. In the present study, we attempted to explain the relationships between the distribution of soil carbon storage with climate, soil types, soil properties and topographical factors across different types of grasslands with different grazing regimes. We measured soil organic carbon in 92 locations at different soil depth increments, from 0 to 100 cm in southwestern China. Among soil types, brown earth soils (Luvisols) had the highest carbon storage with 19.5 ±â€¯2.5 kg m-2, while chernozem soils had the lowest with 6.8 ±â€¯1.2 kg m-2. Mean annual temperature and precipitation, exerted a significant, but, contrasting effects on soil carbon storage. Soil carbon storage increased as mean annual temperature decreased and as mean annual precipitation increased. Across different grassland types, the mean carbon storage for the top 100 cm varied from 7.6 ±â€¯1.3 kg m-2 for temperate desert to 17.3 ±â€¯2.9 kg m-2 for alpine meadow. Grazing/cutting regimes significantly affected soil carbon storage with lowest value (7.9 ±â€¯1.5 kg m-2) recorded for cutting grass, while seasonal (11.4 ±â€¯1.3 kg m-2) and year-long (12.2 ±â€¯1.9 kg m-2) grazing increased carbon storage. The highest carbon storage was found in the completely ungrazed areas (16.7 ±â€¯2.9 kg m-2). Climatic factors, along with soil types and topographical factors, controlled soil carbon density along a soil depth in grasslands. Environmental factors alone explained about 60% of the total variation in soil carbon storage. The actual depth-wise distribution of soil carbon contents was significantly influenced by the grazing intensity and topographical factors. Overall, policy-makers should focus on reducing the grazing intensity and land conversion for the sustainable management of grasslands and C sequestration.

Biochar-amended potting medium reduces the susceptibility of rice to root-knot nematode infections.

BACKGROUND: Biochar is a solid coproduct of biomass pyrolysis, and soil amended with biochar has been shown to enhance the productivity of various crops and induce systemic plant resistance to fungal pathogens. The aim of this study was to explore the ability of wood biochar to induce resistance to the root-knot nematode (RKN) Meloidogyne graminicola in rice (Oryza sativa cv. Nipponbare) and examine its histochemical and molecular impact on plant defense mechanisms. RESULTS: A 1.2 % concentration of biochar added to the potting medium of rice was found to be the most effective at reducing nematode development in rice roots, whereas direct toxic effects of biochar exudates on nematode viability, infectivity or development were not observed. The increased plant resistance was associated with biochar-primed H2O2 accumulation as well as with the transcriptional enhancement of genes involved in the ethylene (ET) signaling pathway. The increased susceptibility of the Ein2b-RNAi line, which is deficient in ET signaling, further confirmed that biochar-induced priming acts at least partly through ET signaling. CONCLUSION: These results suggest that biochar amendments protect rice plants challenged by nematodes. This priming effect partially depends on the ET signaling pathway and enhanced H2O2 accumulation.

Real-time in vivo distal margin selection using confocal laser endomicroscopy in transanal total mesorectal excision for rectal cancer.

BACKGROUND: Transanal total mesorectal excision (TaTME) allows patients with ultralow rectal cancer to be treated with sphincter-saving surgery. However, accurate delineation of the distal resection margin (DRM), which is essential to achieve R0 resection for low rectal cancer in TaTME, is technically demanding. AIM: To assess the feasibility of optical biopsy using probe-based confocal laser endomicroscopy (pCLE) to select the DRM during TaTME for low rectal cancer. METHODS: A total of 43 consecutive patients who were diagnosed with low rectal cancer and scheduled for TaTME were prospectively enrolled from January 2019 to January 2021. pCLE was used to determine the distal edge of the tumor as well as the DRM during surgery. The final pathological report was used as the gold standard. The diagnostic accuracy of pCLE examination was calculated. RESULTS: A total of 86 pCLE videos of 43 patients were included in the analyses. The sensitivity, specificity and accuracy of real-time pCLE examination were 90.00% [95% confidence interval (CI): 76.34%-97.21%], 86.96% (95%CI: 73.74%-95.06%) and 88.37% (95%CI: 79.65%-94.28%), respectively. The accuracy of blinded pCLE reinterpretation was 86.05% (95%CI: 76.89%-92.58%). Furthermore, our results show satisfactory interobserver agreement (κ = 0.767, standard error = 0.069) for the detection of cancer tissue by pCLE. There were no positive DRMs (≤ 1 mm) in this study. The median DRM was 7 mm [interquartile range (IQR) = 5-10 mm]. The median Wexner score was 5 (IQR = 3-6) at 6 mo after stoma closure. CONCLUSION: Real-time in vivo pCLE examination is feasible and safe for selecting the DRM during TaTME for low rectal cancer (clinical trial registration number: NCT04016948).

Thiamine-induced priming against root-knot nematode infection in rice involves lignification and hydrogen peroxide generation.

Thiamine (vitamin B1, VB1) can act as a plant defence trigger, or priming agent, leading to a rapid counterattack on pathogen invasion. In this study, the priming effect of thiamine on rice (Oryza sativa cv. Nipponbare) and its activity against root-knot nematode (Meloidogyne graminicola) infection were evaluated. Thiamine treatment and subsequent nematode inoculation activated hydrogen peroxide (H2O2) accumulation and lignin deposition in plant roots, and this correlated with enhanced transcription of OsPAL1 and OsC4H, two genes involved in the phenylpropanoid pathway. The number of nematodes in rice roots was slightly but significantly reduced, and the development of the nematodes was delayed, whereas no direct toxic effects of VB1 on nematode viability and infectivity were observed. The combined application of thiamine with l-2-aminooxy-3-phenylpropionic acid (AOPP), an inhibitor of phenylalanine ammonia-lyase (PAL), significantly hampered the VB1-priming capacity. These findings indicate that thiamine-induced priming in rice involves H2O2 and phenylpropanoid-mediated lignin production, which hampers nematode infection. Further cellular and molecular studies on the mechanism of thiamine-induced defence will be useful for the development of novel nematode control strategies.

The effects of nitrogen fertilization on N2O emissions from a rubber plantation.

To gain the effects of N fertilizer applications on N2O emissions and local climate change in fertilized rubber (Hevea brasiliensis) plantations in the tropics, we measured N2O fluxes from fertilized (75 kg N ha(-1) yr(-1)) and unfertilized rubber plantations at Xishuangbanna in southwest China over a 2-year period. The N2O emissions from the fertilized and unfertilized plots were 4.0 and 2.5 kg N ha(-1) yr(-1), respectively, and the N2O emission factor was 1.96%. Soil moisture, soil temperature, and the area weighted mean ammoniacal nitrogen (NH4(+)-N) content controlled the variations in N2O flux from the fertilized and unfertilized rubber plantations. NH4(+)-N did not influence temporal changes in N2O emissions from the trench, slope, or terrace plots, but controlled spatial variations in N2O emissions among the treatments. On a unit area basis, the 100-year carbon dioxide equivalence of the fertilized rubber plantation N2O offsets 5.8% and 31.5% of carbon sink of the rubber plantation and local tropical rainforest, respectively. When entire land area in Xishuangbanna is considered, N2O emissions from fertilized rubber plantations offset 17.1% of the tropical rainforest's carbon sink. The results show that if tropical rainforests are converted to fertilized rubber plantations, regional N2O emissions may enhance local climate warming.

Spironolactone lowers portal hypertension by inhibiting liver fibrosis, ROCK-2 activity and activating NO/PKG pathway in the bile-duct-ligated rat.

OBJECTIVE: Aldosterone, one of the main peptides in renin angiotensin aldosterone system (RAAS), has been suggested to mediate liver fibrosis and portal hypertension. Spironolactone, an aldosterone antagonist, has beneficial effect on hyperdynamic circulation in clinical practice. However, the mechanisms remain unclear. The present study aimed to investigate the role of spionolactone on liver cirrhosis and portal hypertension. METHODS: Liver cirrhosis was induced by bile duct ligation (BDL). Spironolactone was administered orally (20 mg/kg/d) after bile duct ligation was performed. Liver fibrosis was assessed by histology, Masson's trichrome staining, and the measurement of hydroxyproline and type I collagen content. The activation of HSC was determined by analysis of alpha smooth muscle actin (α-SMA) expression. Protein expressions and protein phosphorylation were determined by immunohistochemical staining and Western blot analysis, Messenger RNA levels by quantitative real time polymerase chain reaction (Q-PCR). Portal pressure and intrahepatic resistance were examined in vivo. RESULTS: Treatment with spironolactone significantly lowered portal pressure. This was associated with attenuation of liver fibrosis, intrahepatic resistance and inhibition of HSC activation. In BDL rat liver, spironolactone suppressed up-regulation of proinflammatory cytokines (TNFα and IL-6). Additionally, spironolactone significantly decreased ROCK-2 activity without affecting expression of RhoA and Ras. Moreover, spironolactone markedly increased the levels of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS and the activity of NO effector-protein kinase G (PKG) in the liver. CONCLUSION: Spironolactone lowers portal hypertension by improvement of liver fibrosis and inhibition of intrahepatic vasoconstriction via down-regulating ROCK-2 activity and activating NO/PKG pathway. Thus, early spironolactone therapy might be the optional therapy in cirrhosis and portal hypertension.

[Effects of shading on photosynthesis characteristics of Photinia x frasery and Aucuba japonica var. variegata].

This paper studied the effects of different shading (light transmittance 20%, 40%, 60%, and 100%) on the photosynthesis characteristics of two ornamental foliage plants Photinia x frasery and Aucuba japonica var. variegata. After shading for six weeks, the net photosynthesis rates of two plants measured ex situ under natural light enhanced, compared to those measured in situ, and, with the increase of shading degree, the net photosynthetic rates had an increasing trend, with the maximum being 9.7 micromol x m(-2) x s(-1) for Photinia x frasery and 8.3 micromol x m(-2) x s(-1) for Aucuba japonica var. variegata. In the meantime, the transpiration rates of the two plants increased significantly. Shading increased the chlorophyll a, b, and a+b contents and the chlorophyll/carotenoids ratio, decreased the chlorophyll a/b, but less affected the carotenoids content. The phenotypic plasticity index (PPI) of net photosynthesis rate and transpiration rate of Photinia x frasery and Aucuba japonica var. variegate was 2.08 and 3.21, and 0.55 and 1.60, respectively. The chlorophyll and carotenoids contents of the two plants were relatively stable, indicating the minor influence of external environment factors on pigments. Aucuba japonica var. variegata had a higher shading tolerance than Photinia x frasery.

Soluble intercellular adhesion molecule-1, D-lactate and diamine oxidase in patients with inflammatory bowel disease.

AIM: To study the levels of serum soluble intercellular adhesion molecule-1 (sICAM-1), plasma D-lactate and diamine oxidase (DAO) in patients with inflammatory bowel disease (IBD), and the potential clinical significance. METHODS: Sixty-nine patients with IBD and 30 healthy controls were included in this study. The concentration of sICAM-1 was detected with enzyme-linked immunosorbent assay, the level of D-lactate and DAO was measured by spectroscopic analysis, and the number of white blood cells (WBC) was determined by routine procedure. RESULTS: The levels of sICAM-l, DAO, and WBC in IBD patients were significantly higher than those in the control group (P < 0.01). sICAM-l in IBD patients was found to be closely related to the levels of DAO and D-lactate (212.94 +/- 69.89 vs 6.35 +/- 2.35, P = 0.000), DAO 212.94 +/- 69.89 vs 8.65 +/- 3.54, P = 0.000) and WBC (212.94 +/- 69.89 vs 7.40 +/- 2.61, P = 0.000), but no significant difference was observed between patients with ulcerative colitis and patients with Crohn's disease. The post-treatment levels of sICAM-l, D-lactate and WBC were significantly lower than before treatment (sICAM-l 206.57 +/- 79.21 vs 146.21 +/- 64.43, P = 0.000), (D-lactate 1.46 +/- 0.94 vs 0.52 +/- 0.32, P = 0.000) and (WBC 7.24 +/- 0.2.33 vs 5.21 +/- 3.21, P = 0.000). CONCLUSION: sICAM-1, D-lactate and DAO are closely related to the specific conditions of IBD, and thus could be used as a major diagnostic index.

[Effects of Changyanqing decoction on the expressions of interleukin-10 and intercellular adhesion molecule-1 in rats with ulcerative colitis].

OBJECTIVE: To investigate the effect of Changyanqing decoction, a traditional Chinese medicinal preparation, on the expressions of interleukin-10 (IL-10) and intercellular adhesion molecule-1 (ICAM-1) in the colon mucosa of rats with ulcerative colitis. METHODS: The rats with ulcerative colitis induced by trinitrobenzene sulphonic acid and ethanol enema were randomly divided into 3 groups, namely the model group, sulfasalazine (SASP) group, and Changyanqing decoction group. Daily treatment with intragastric administration and enema of normal saline, SASP (100 mg/kg), and Changyanqing decoction (39.75 mg/kg), respectively, were administered 24 h after the establishment of colitis till the end of the experiment. Another group of rats was used as the normal control group. The disease activity index (DAI) and colon mucosa damage index (CMDI) of the rats were calculated. The activity of myeloperoxidase (MPO) was measured by biochemical method, and the expressions of IL-10 and ICAM-1 protein were measured by ELISA and immunohistochemistry, respectively. RESULTS: Compared with the normal group, the model group showed significantly increased DAI, CMDI, HS score and MPO activity in the colon tissues (P < 0.01), with also significantly increased expression of ICAM-1 (P < 0.01) and decreased expression of IL-10 in the rat colon mucosa (P < 0.01). Treatment with Changyanqing decoction resulted in a significant reduction in DAI, CMDI, HS score and MPO activity (P < 0.01), and decreased the expression of ICAM-1 (P < 0.01) and increased the expression of IL-10 (P < 0.01) in the colon mucosa. The expression of ICAM-1 in the colon mucosa was positively correlated to that of IL-10 (r = 0.927, P < 0.01) and the activity of MPO (r = 0.621, P < 0.01). CONCLUSIONS: Changyanqing decoction has protective effect against rat ulcerative colitis, mediated probably by enhancement of IL-10 expression and reduction in ICAM-1 expression and neutrophil infiltration.