[Soluble Uric Acid Activates NLRP3 Inflammasome in Myocardial Cells Through Down-regulating UCP2].

OBJECTIVE: To determine the H9C2 cell damage and NLRP3 inflammasome activation trigged by soluble uric acid (UA). METHODS: H9C2 cells were treated with UA. The cellular damage was examined after 12 h, 24 h and 48 h of treatment using MTS and lactic dehydrogenase (LDH). The apoptosis of H9C2 cells was analyzed by flow cytometry (FCM). NLRP3 inflammasome activation was reflected by the protein levels of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC) and Caspase-1 detected by Western blot. The mitochondria and cytoplasm were separated and the release of cytochrome C was detected by Western blot to analyze the damage of mitochondria. The impacts of NAC, a ROS inhibitor, on the cell viability and NLRP3 inflammasome activation were analyzed. The expression of UCP2 was detected by Western blot and immunofluorescence (IF). RESULTS: Dose response and time dependent effects of UA on cellular damage and cell apoptosis was observed. UA up-regulated the expression of NLRP3 inflammasome-related molecules. UA damaged the mitochondria. NAC improved the cell viability and inhibited NLRP3 inflammasome activation. UA down-regulated the expression of UCP2. CONCLUSION: Soluble UA can down-regulate the expression of UCP2, damage the mitochondria and activate NLRP3 inflammasome, resulting in cellular damage of H9C2 cells.

[Characteristics of humidity and temperature variations and CO2 exchange of mobile dunes at different space-time scales in Horqin sandy land, China].

Terrestrial carbon cycle plays a key role in driving climate change and ecosystem carbon balance. Understanding the variations of humidity and temperature and CO2 exchanges are meaningful to reveal the law and mechanism of regional carbon cycles in deserts. We examined the near surface humidity, temperature variations, and CO2 exchanges by eddy covariance and Bowen ratio systems in a typical mobile dune of Horqin sandy land. We analyzed the relationships between water-heat and CO2 exchanges of 0 to 10 m vertical height at daily and seasonal scales were analyzed. The results showed that the vertical variations of near surface temperature ranged from 0.4 ℃ to 2 ℃ and decreased with the increases of height from April to September, but with an opposite pattern in other months. The seasonal variation of air relative humidity was greater than 40%. During the growing season of 2018, the averaged daily net ecosystem carbon exchange (NEE) was -0.02 mg·m-2·s-1. The annual averaged daily NEE was 0.003 mg·m-2·s-1, indicating that the mobile dunes were carbon sources at the whole year scale. The vertical differences of temperature and humidity well fitted the NEE. The inflexion points of the fitting curve were at 10% humidity and 0.5 ℃ temperature, respectively. At the scalem of the year, the NEE fitting result of temperature was better than that of humidity, with the inflexion points at 17 ℃ and 65% humidity, respectively. In the growing season, the near surface vertical temperature difference was negative, which would inhibit CO2 absorption of mobile dunes. The circumstances of high humidity would promote the absorption of atmospheric CO2. Across different time and vertical height, the variations of humidity and temperature were closely related to CO2 exchanges, which affected carbon sink and source of mobile dunes. Carbon budget was more sensitive to temperature than humidity.

[Deep water leakage from semi-mobile dunes in semi-arid regions and its response to rainfall patterns]. / åŠå¹²æ—±åœ°åŒºåŠæµåŠ¨æ²™ä¸˜æ°´åˆ†æ·±å±‚æ¸—æ¼é‡åŠå ¶å¯¹é™é›¨æ ¼å±€çš„å“åº”.

As the main source of soil moisture supply in desertified areas, rainfall has a profound impact on soil moisture changes and plays an important role in deep soil moisture replenishment. Based on the Hydrus-1D model with optimized parameters, we analyzed the dynamic change process of the leakage in the 200 cm deep layer of the semi-mobile dunes in Horqin Sandy Land and its response to the rainfall patterns. The results showed that the averaged leakage replenishment of semi-mobile dunes was 254.31 mm from April to October each year during 2016 to 2019, accoun-ting for 61.8% of the rainfall in the same period. Deep leakage mainly occurred from June to August, accounting for 72.8% of the total. The leakage rate was distributed between 0.03-2.70 mm·h-1, with the maximum leakage rate occurring under heavy rainfall and frequent rainfall events. The deep soil water supplied by rainfall infiltration was affected by the amount of rainfall, rainfall intensity, duration of precipitation and soil moisture content in the earlier period. Precipitation events with long duration and small rainfall intensity were more conducive to deep water lea-kage, with a significant positive correlation between the leakage and rainfall (R2=0.85). 16-18 mm rainfall was the threshold for the leakage of 200 cm soil depth. The high-frequency rainfall event usually reached peak after 17-38 hours, with the entire leakage process being more than 164 hours. Accurate estimation of deep leakage has theoretical and practical significance for water resource assessment and ecological construction in desertified areas.

Simulation of evapotranspiration for the mobile and semi-mobile dunes in the Horqin Sandy Land using the Shuttleworth-Wallace model.

Terrestrial evapotranspiration (ET) plays a crucial role in climate regulation and the maintenance of regional water balance. Quantitative estimation of ET and its partitioning are important for revealing the eco-hydrological processes in arid and semi-arid areas. Using the in situ data sampled by the meteorological monitoring system, the Shuttleworth-Wallace (S-W) model was applied to simulate and partition ET in the mobile and semi-mobile dunes of the Horqin sandy land during the growing season in 2017. The eddy covariance system was used to verify the simulated ET. The results were as follows: the simulated ET (308 mm) was very close to the eddy covariance observed ET (296 mm) during the whole growing season, indicating the applicability of the S-W model for ET estimation in this area. The ET rate at the vigorous growth stage (192 mm) was larger than those at the late and early growth stages (71 and 45 mm, respectively) which accounted for 62.3%, 23.1%, and 14.6% of the total, respectively. The simulated ET was close to the eddy covariance observed ET at the daily time-scale. The simulation performance of the S-W model for clear days was better than for cloudy or rainy days. The simulated ET rate was always smaller than the eddy covariance observed ET in the cloudy or rainy days. According to the model, the evaporation (E) from soil was 176 mm and the transpiration (T) from plants was 132 mm, accounting for 57.1% and 42.9% of the ET, respectively, suggesting that water use efficiency of the sand dune was low. The characteristics of ET varied substantially under the sustained drought and precipitation events. Compared to T from plants, E from soil was more sensitive to precipitation.

[Characteristics of soil greenhouse gas flux and its driving factors in Horqin sand dune-mea-dow wetland cascade ecosystems.] / 科尔沁沙丘-è‰ç”¸æ¢¯çº§ç”Ÿæ€ç³»ç»ŸåœŸå£¤æ¸©å®¤æ°”ä½“é€šé‡ç‰¹å¾åŠå ¶å½±å“å› ç´ .

Using the static chamber-GC technique, greenhouse gas (CO2, CH4, N2O) fluxes of sand dunes and meadow wetlands were measured in a typical sand dune-meadow cascade ecological zone of Horqin. The dynamics of the greenhouse gas fluxes and driving factors were analyzed. The results showed that soil CH4 flux underwent absorption during the growing season, with average CH4 fluxes of semi-mobile dunes and meadow wetlands were -52.7 µg·m-2·h-1 and -34.7 µg·m-2·h-1, respectively, ranging from -176.1 to 49.8 µg·m-2·h-1. The peak of CH4 absorption in the growing season occurred at August 22nd, 2017. In August and September, the months with heavy rainfall, the CH4 flux in meadow wetlands showed continuous emission, being significantly different from that in semi-mobile dunes. The peak of N2O flux during the growing season was at July 21st. The monthly average N2O flux in semi-mobile dunes was following the order of July > August > September > June > May. Soil temperature and moisture were the key factors affecting CO2 and CH4 fluxes, whereas the N2O flux was mainly affected by soil temperature. The soil temperature sensitivity (Q10) showed the sequence of semi-mobile dune (1.009) < meadow wetland (1.474). The water stress rendered the greenhouse gas fluxes in semi-mobile dunes being less sensitive to soil temperature change than that in meadow wetlands.

[Effects of temperature and moisture on net ecosystem CO2 exchange over a meadow wetland in the Horqin, China.] / 温度和水分对科尔沁草甸湿地净生态系统碳交换量的影响.

Using the eddy covariance technique, the Bowen-ratio meteorological and soil monitoring system, we analyzed the CO2 flux dynamics and its responses to temperature and moisture over a meadow wetland in the Horqin during the growing season (from May to September) in 2016. The results showed that the accumulated net ecosystem CO2 exchange (NEE) was -766.18 g CO2·m-2 during the growing season. The gross primary productivity (GPP) and ecosystem respiration (Re) were 3379.89 and 2613.71 g CO2·m-2, respectively. The ratio of Re to GPP was 77.3%, indicating that this ecosystem was an obvious carbon sink. The average diurnal variation of NEE exhibited a single peak U-shaped curve with an absorption of CO2 from May to mid August and a release of CO2 from late August to September. Daytime NEE well fitted with the photosynthetically active radiation (PAR) by a rectangular hyperbolic function. Meanwhile, the relationship was affected by the environmental factors, including vapor pressure deficit (VPD), soil water content (SWC) and air temperature (Ta). Regression analysis showed that the VPD and SWC for the maximum daytime NEE were 1.75 kPa and 35.5%, respectively. Daytime NEE increased with Ta, and with no inhibitory effect on the daytime NEE when it reached the maximum. Nighttime NEE had an exponential relationship with soil temperature (Ts). During the entire growing season, the temperature sensitivity of the ecosystem respiration (Q10) was 2.4, which was negatively related to SWC. The nighttime NEE was controlled by both Ts and SWC.