Cystathionine γ-lyase-derived H2S negatively regulates thymic egress via allosteric inhibition of sphingosine-1-phosphate lyase.

Thymic egress is a crucial process for thymocyte maturation, strictly regulated by sphingosine-1-phosphate lyase (S1PL). Recently, cystathionine γ-lyase (CSE), one of the enzymes producing hydrogen sulfide (H2S), has emerged as a vital immune process regulator. However, the molecular connection between CSE, H2S and thymic egress remains largely unexplored. In this study, we investigated the regulatory function of CSE in the thymic egress of immune cells. We showed that genetic knockout of CSE or pharmacological inhibition by CSE enzyme inhibitor NSC4056 or D,L-propargylglycine (PAG) significantly enhanced the migration of mature lymphocytes and monocytes from the thymus to the peripheral blood, and this redistribution effect could be reversed by treatment with NaHS, an exogenous donor of H2S. In addition, the CSE-generated H2S significantly increased the levels of S1P in the peripheral blood, thymus and spleen of mice, suppressed the production of proinflammatory cytokines and rescued pathogen-induced sepsis in cells and in vivo. Notably, H2S or polysulfide inhibited S1PL activity in cells and an in vitro purified enzyme assay. We found that this inhibition relied on a newly identified C203XC205 redox motif adjacent to the enzyme's active site, shedding light on the biochemical mechanism of S1PL regulation. In conclusion, this study uncovers a new function and mechanism for CSE-derived H2S in thymic egress and provides a potential drug target for treating S1P-related immune diseases.

[Thinking from Horqin Grassland to Horqin Sandy Land]. / 从科尔沁草原到科尔沁沙地的思考.

We systematically elaborated and compared the spatial scope and landscape changes of Horqin Grassland and Horqin Sand Land from their definitions and ranges. Horqin Grassland is an area with geographical units named after Mongolian tribes, but the boundary is unclear. Horqin Sand Land is also an area that borrows tribal names, but has independent topographic and geomorphic units, and clear boundaries. Horqin Grassland and Horqin Sand Land belong to two spatial regions that are both cross and different. The area and range of Horqin Grassland are larger than that of Horqin Sand Land which has obvious regional characteristics, and is a typical and research object area to study the development and restoration of aeolian desertification. Based on those cognition, we summarized the technologies and example models of comprehensive land management and desertification controlling over the years, and finally sorted out what should be focused on in the future to serve the annihilation war against desertification for Horqin Sand Land.

[Research on the clinical application of drainage tube after the operation of percutaneous endoscopic lumbar discectomy].

OBJECTIVE: To investigate the clinical significance and related factors of drainage tube after percutaneous endoscopic lumbar discectomy(PELD). METHODS: The clinical data of 151 patients with lumbar disc herniation who underwent PELD from January 2019 to September 2019 was retrospectively analyzed. According to whether the drainage tube was used after operation, the patients were divided into drainage tube group and non drainage tube group. The placement time and total drainage volume were recorded. The characteristics of patients, such as age, gender, body mass index, lumbar disc herniation segment, smoking history, basic diseases and whether taking anticoagulants, were analyzed by single factor and multiple factor. RESULTS: Drainage tubes were used in 32 patients after PELD. There were statistical differences in visual analogue scale(VAS) and Japanese Orthopaedic Assiciation(JOA) scores between postoperative and preoperative of that in two groups(P<0.05). There were statistical differences in VAS and JOA scores at discharge between two groups(P<0.05), while there were no statistical differences at other time points(P>0.05). Univariate analysis showed that age, basic diseases and whether taking anticoagulants were related to the use of drainage tube, but gender, body mass index, lumbar disc herniation segment and smoking history were not significantly related to the use of drainage tube. Multivariate analysis showed that elderly patients, complicated with hypertension and diabetes, taking anticoagulants were related to the use of drainage tube. CONCLUSION: The use of drainage tube after percutaneous endoscopic lumbar discectomy can improve the symptoms of lumbar and leg pain in early stage. For elderly patients with hypertension, diabetes and taking anticoagulants drugs, drainage tube can be considered after transforaminal endoscopy.

Increased pollinator service and reduced pollen limitation in the fixed dune populations of a desert shrub.

Evaluations of restoration success usually focus on the structural aspects of ecosystems. Pollination, as an important functional aspect, is often overlooked. Here, the shifts in pollinator assemblage and pollen limitation in the desert shrub Caragana microphylla were examined along a restoration gradient in Horqin Sand Land, northern China. We identified seven species of bees; however, only four bee species were found to be effective pollinators, with Xanthosaurus remota dominating in the fixed dunes, and with no bee species or only a single species, X. remota, being observed in the semi-fixed and mobile dunes. Flower visitation rate was nearly ten times higher in the fixed dunes than in the mobile and semi-fixed dunes. Experimental floral manipulations revealed that the fixed dune populations experienced less pollen limitation, along with the increase in pollinator availability. Between the mobile and semi-fixed dune populations, pollen limitation was severe and at similar levels. The intensity of pollen limitation was negatively related to pollinator abundance and richness. Overall, the dependence on pollinators for reproduction may be an important constraint that limits persistence in this system. Increased pollinator service during the restoration process may ameliorate pollen limitation, benefiting the restoration of vegetation in this semiarid sandy area.

Earlier flowering did not alter pollen limitation in an early flowering shrub under short-term experimental warming.

In animal pollinated plants, phenological shifts caused by climate change may have important ecological consequences. However, no empirical evidence exists at present on the consequences that flowering phenology shifts have on the strength of pollen limitation under experimental warming. Here, we investigated the effects of experimental warming on flowering phenology, flower density, reproductive success, and pollen limitation intensity in Caragana microphylla and evaluated whether earlier flowering phenology affected plant reproduction and the level of pollen limitation using warmed and unwarmed open top chambers in the Horqin Sandy Land of Inner Mongolia, northern China. The results of this study indicated that artificial warming markedly advanced flower phenology rather than extending the duration of the flowering. Additionally, warming was found to significantly reduce flower density which led to seed production reduction, since there were insignificant effects observed on fruit set and seed number per fruit. Experimental floral manipulations showed that warming did not affect pollen limitation. These results revealed the negative effects of advanced phenology induced by warming on flower density and reproductive output, as well as the neutral effects on reproductive success and pollen limitation intensity of long surviving plants.

[Structural characteristics of Artemisia frigid community at different succession stages in Horqin Sandy Land].

Taking space as a substitute for time, this paper studied the species composition and species diversity of Artemisia frigid community at three succession stages in Horqin Sandy Land. The three succession stages were Periploca sepium-A. frigida community, Periploca sepium-A. frigida+A. halodendron community, and A. frigida-Cleistogenes squarrosa community, all dominated by the plants of Compositae, Chenopodiaceae and Gramineae. The species number and family number in the communities and the species number of Gramineae decreased with succession, while the percentages of Compositae and Gramineae species increased. The species diversity of the communities was in the order of P. sepium-A. frigida+A. halodendron > P. sepium-A. frigida >A. frigida-C. squarrosa. No obvious difference was observed in the species composition among the three communities. In the three communities, A. frigida had the highest coverage, and the coverage increased with succession.

[Leaf nitrogen and phosphorus stoichiometry in typical desert and desertified regions, north China].

Characteristics of leaf nitrogen and phosphorus stoichiometry at regional scale is key factors to understand spatial pattern, forecast change trends and reveal responses of terrestrial ecosystem to global change. In this study, pattern of leaf nitrogen and phosphorus of 214 plants was investigated to elucidate their relationships with rainfall and temperature in typical desert and desertified regions of northern China. The results showed that average leaf nitrogen concentration, average leaf phosphorus concentrations, and leaf N/P of 214 species are (24.45 +/- 8.1) mg/g, (1.74 +/- 0. 88) mg/g, 15.77 +/- 7.5 in these regions of northern China, respectively. Compared with other studies at global, national or regional scale, leaf nitrogen and phosphorus concentrations are significantly higher in this study (p < 0.001). However, leaf N/P didn't show any significant differences with other studies. This implies that leaf N/P is generally well-constrained. One-way ANOVA analysis showed that leaf N, P, and N/P varied significantly among trees, shrubs, graminoids, and forbs. Leaf N concentration in shrubs, forbs and leaf P concentration in forbs are averagely higher than those in other life-forms, respectively. This implies that nutrient use strategies are significantly different among plant life-forms. There are no significant differences in leaf nitrogen concentration among each typically desert and desertified region. However, Leaf phosphorus concentration and leaf N/P are significantly different among each typically desert and desertified regions. Leaf phosphorus concentrations are relatively high in Kerqin Sand Land and Mowuso Sand Land. Leaf N/P of most species in Talimu basin, Zhunger Basin, and Alashan is higher than 16, and lower than 14 of most species in Kerqin Sand land. This means that nutrient constraining in different regions varies greatly. Correlations analysis showed that leaf N, P, and N/P are significantly correlated with annual precipitation, but not significantly correlated with annual mean temperature in desert and desertified regions of northern China.

[Spatial heterogeneity of soil organic carbon and total nitrogen of sandy grassland in the restoration of degraded vegetation in Horqin Sandy Land, northern China].

Based on the field investigation and lab analysis, we used geostatistics method to examine the spatial heterogeneity of soil organic carbon and total nitrogen in a 0-year fenced mobile dune (MD11), an 11-year fenced mobile dune (MD11) and a 20-year fenced mobile dune (MD20) in Horqin Sandy Land. The results showed that the average values of vegetation cover, species number and diversity, soil organic carbon and total nitrogen (0-20 cm) contents increased with the increase in fenced age of mobile dunes. Geostatistical analysis showed that the proportions of relative structural variance C/(C0 + C) of soil organic carbon and total nitrogen in each dune were over 65% , which suggested that they had obvious spatial autocorrelation. Calculated ranges of spatial autocorrelation for soil organic carbon and total nitrogen were 58.39 m and 91.00 m (MDO), 28.59 m and 23.61 m (MD11) and 63.31 m and 61.05 m (MD20), respectively. The analysis from semivariance calculated parameters and spatial distributed maps showed that the spatial heterogeneity of soil organic carbon and total nitrogen firstly increased from MDO to MD11 then decreased from MD11 to MD20. Correlation analysis indicated that there were significantly positive correlations among vegetation cover, species richness and diversity index, soil organic carbon and total nitrogen (p < 0.01) . The analyzed results indicate that the spatial distributions of soil organic carbon and total nitrogen are most strongly related the topography features and vegetation changes in sand dune ecosystems prone to wind erosion. The accumulation and spatial haterogeniety of soil organic carbon and total nitrogen in the restoration of dune degraded vegetation are greatly affected by vegetation restoration succession.

Deposition of atmospheric (137)Cs in Japan associated with the Asian dust event of March 2002.

Considerable deposition of (137)Cs was observed in the northwestern coastal area of Japan in March 2002. Since there were no nuclear explosions or serious nuclear accidents in the early 2000s, transport of previously contaminated dust appears to be the only plausible explanation for this event. In March 2002, there was a massive sandstorm on the East Asian continent, and the dust raised by the storm was transported across the sea to Japan. This dust originated in Mongolia and northeastern China, in an area distant from the Chinese nuclear test site at Lop Nor or any other known possible sources of (137)Cs. Our radioactivity measurements showed (137)Cs enrichment in the surface layer of grassland soils in the area of the sandstorm, which we attributed to accumulation as a result of past nuclear testing. We suggest that the grassland is a potential source of (137)Cs-bearing soil particles. Since the late 1990s, this area has experienced drought conditions, resulting in a considerable reduction of vegetation cover. We attribute the prodigious release of (137)Cs-bearing soil particles into the atmosphere during the sandstorm and the subsequent deposition of (137)Cs in Japan to this change.

[Characteristics of Caragana microphylla sap flow and water consumption under different weather conditions on Horqin sandy land of northeast China].

Employing heat balance Dynamax packaged sap flow measuring system and automatic weather recording system, the sap flow of artificial Caragana microphylla community on Horqin sandy land of northeast China was monitored consecutively in 2006, and the photosynthetically effective radiation, air temperature, relative humidity and wind velocity were measured synchronously. According to the manual records of weather conditions, four most representative weather conditions were gathered up to analyze the relationships of C. microphylla sap flow and its single branch water consumption with test meteorological factors. The results showed that under high air temperature and intense radiation on sunny days, the diurnal variation of C. microphylla sap flow appeared a broad peak curve, so as to adapt the circumstance of drought and water shortage via lower transpiration. The diurnal variations of sap flow and its dominant affecting factors differed with weather conditions, and photosynthetically effective radiation was always the dominant factor affecting the sap flow. The variation of the sap flow was the result of comprehensive effects of multi-meteorological factors, and the overall variation trend of water consumption of single branch was declined in the order of sunny days > cloudy days > windy days > rainy days, with the mean value being 459, 310, 281 and 193 mg x d(-1), respectively.

The relative importance of pre- and post-germination determinants for recruitment of an annual plant community on moving sandy land.

BACKGROUND AND AIMS: The relative importance of pre- and post-germination determinants for recruitment of natural plant communities is rarely explored. An annual plant community on moving sandy land was chosen for a case study. Answers to the following questions were sought: (a) Does recruitment of new individuals within the community of annual plants differ in time and space? (b) Is there spatial concordance between seed deposition, seedling emergence, survival and recruitment? (c) What are the direct and indirect effects of pre- and post-germination determinants on plant recruitment. METHODS: An integrative approach combining investigation of natural recruitment processes with regression, correlation and path analyses was adopted. Data on seed deposition and seedling recruitment were collected by monitoring the number of seeds deposited in the top 5 cm of the soil and the numbers of seedlings emerged and recruited from all annual plants at sites to a range of distances from the existing shrub Artemisia halodendron (Asteraceae) in eight compass directions for two consecutive growing seasons. KEY RESULTS: Community-level recruitment was strongly affected by inter-annual rainfall variation and was highly site- and density-dependent. Low recruitment rate in this system was due to low emergence rate and low post-emergence survival rate. Of the pre- and post-germination determinants studied, it was the number of seedlings which emerged and the post-emergence survival rate that had the greatest direct effects on recruitment, with a combination of both variables explaining the majority of the variance (97 %) in recruitment. CONCLUSIONS: This study suggests that post-germination determinants (emergence and survival) rather than pre-germination determinants (seed deposition) substantially determined the final pattern of recruitment. Although the density of seeds deposited did not have a significant direct effect on recruitment, it contributed to observed variation in recruitment indirectly through density-dependent emergence of seedlings.

Changes in soil properties after establishment of Artemisia halodendron and Caragana microphylla on shifting sand dunes in semiarid Horqin Sandy Land, northern China.

In the semiarid Horqin sandy land of northern China, establishment of artificial sand-fixing shrubs on desertified sandy lands is an effective measure to control desertification and improve the regional environment. Caragana microphylla Lam. and Artemisia halodendron Turcz. ex Bess. are two of the dominant native shrub species, which are adapted well to windy and sandy environments, and thus, are widely used in revegetation programs to control desertification in Horqin region. To assess the effects of artificially planting these two shrub species on restoration of desertified sandy land, soil properties and plant colonization were measured 6 years after planting shrubs on shifting sand dunes. Soil samples were taken from two depths (0-5 cm and 5-20 cm) under the shrub canopy, in the mid-row location (alley) between shrub belts, and from nonvegetated shifting sand dune (as a control). Soil fine fractions, soil water holding capacity, soil organic C and total N have significantly increased, and pH and bulk density have declined at the 0-5-cm topsoil in both C. microphylla and A. halodendron. At the 5-20 cm subsurface soil, changes in soil properties are not significant, with exception of bulk density and organic C concentration under the canopy of A. halodendron and total N concentration under the canopy of C. microphylla. Soil amelioration processes are initiated under the shrub canopies, as higher C and N concentrations were found under the canopies compared with alleys. At the same time, the establishment of shrubs facilitates the colonization and development of herbaceous species. A. halodendron proved to have better effects in fixing the sand surface, improving soil properties, and restoring plant species in comparison to C. microphylla.