[Response of radial growth of different timberline species to climate change in Yading Nature Reserve, Sichuan, China]. / å››å·äºšä¸è‡ªç„¶ä¿æŠ¤åŒºä¸åŒæž—çº¿æ ‘ç§å¾„å‘ç”Ÿé•¿å¯¹æ°”å€™å˜åŒ–çš„å“åº”.

The radial growth of trees in alpine timberline is particularly sensitive to climate change. We sampled and disposed tree-ring cores of three coniferous tree species including Juniperus saltuaria, Abies forrestii, and Larix potaninii at alpine timberline in Yading Nature Reserve. The standard tree-ring chronology was used to explore the response of radial growth of different timberline species to climate change. The results showed that radial growth of L. potaninii increased after 2000, while that of A. forrestii declined after 2002, and J. saltuaria showed a significant decreasing growth trend in the past 10 years. Such results indicated divergent growth responses to climate factors among the three tree species at alpine timberline. The radial growth of J. saltuaria was sensitive to temperature, and was positively correlated with the minimum temperature from previous October to current August, the mean tempera-ture from previous November to current April and from current July to October, but was negatively associated with the relative humidity from current July to October. The radial growth of A. forrestii showed negative correlation with mean temperature and the maximum temperature from May to June in the current year, while it exhibited positive association with the relative humidity and the Palmer drought severity index from May to June in the current year. L. potaninii radial growth was positively associated with mean temperature and the maximum temperature of November-December in the previous year, the maximum temperature of current March and mean temperature of current August. The temporal stability of climate-growth relationship varied among different timberline species. The positive correlation between radial growth of A. forrestii and J. saltuaria and temperature gradually decreased, while the posi-tive relationship of L. potaninii radial growth and temperature gradually increased. Under the background of climate warming, rapid rise in surface air temperatures may promote the radial growth of L. potaninii, while inhibit that of J. saltuaria and A. forrestii, which may change the position of regional timberline.

[Response of radial growth of Pinus wallichiana to climate change in Mount Qomolangma, Tibet, China]. / è¥¿è—ç å³°åœ°åŒºä¹”æ¾å¾„å‘ç”Ÿé•¿å¯¹æ°”å€™å˜åŒ–çš„å“åº”.

Global warming would significantly impact tree growth in the Tibetan Plateau. However, the specific effects of climate change on the radial growth of Pinus wallichiana in Mount Qomolangma are still uncertain. To investigate the responses of radial growth of P. wallichiana to climate change, we analyzed tree-ring samples in Mount Qomolangma. We removed the age-related growth trends and established three chronologies by using the modified negative exponential curve, basal area index, and regional curve standardization, and conducted Pearson correlation and moving correlation analyses to examine the association between radial growth of P. wallichiana and climatic factors. The results showed that this region had experienced a significant upward trend in temperature and that the Palmer drought severity index (PDSI) indicated a decreasing trend since 1980s, while the relative humi-dity changed from a significant upward to a downward trend around 2004, implying the climate shifted toward warmer and drier. Results of Pearson correlation analysis indicated a significant and positive relationship between the radial growth of P. wallichiana and the minimum temperature of April-June and July-September, and precipitation of January-April in the current year. The radial growth of P. wallichiana was significantly and negatively associated with the relative humidity of June, July, and August in the current year. As temperature rose after 1983, the relationship between radial growth of P. wallichiana and the minimum temperature in July and September of the current year increased from a non-significant association to a significant and positive association, while the relationship between radial growth of P. wallichiana and relative humidity in August and precipitation in September of the current year changed from non-significant correlation to a significant and negative correlation. Results of the moving correlation analysis suggested that the radial growth of P. wallichiana showed a significant and stable correlation with the July-September minimum temperature of the current year. Under the background of climate warming, the rapid increases of temperature would accelerate the radial growth of P. wallichiana in Mount Qomolangma.

Propionate promotes gluconeogenesis by regulating mechanistic target of rapamycin (mTOR) pathway in calf hepatocytes.

Enhancing hepatic gluconeogenesis is one of the main modes of meeting the glucose requirement of dairy cows. This study attempted to determine whether the gluconeogenesis precursor propionate had an effect on the expression of the main genes involved in gluconeogenesis in calf hepatocytes and elucidate the associated mechanisms. Calf hepatocytes were obtained from 5 healthy calves (1 d old; 30 to 40 kg) and exposed to 0-, 1-, 2.5-, or 5-mM sodium propionate (NaP), which is known to promote the expression of genes involved in the gluconeogenesis pathway, including fructose 1,6-bisphosphatase, phosphoenolpyruvate carboxykinase, and glucose-6-phosphatase. With regard to the underlying mechanism, propionate promoted the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha, hepatocyte nuclear factor 4, and forkhead box O1 (transcription factors that regulate the expression of hepatic gluconeogenic genes) by promoting mammalian target of rapamycin complex 1 (mTORC1), but inhibiting mTORC2 activity (P < 0.01). We also established a model of palmitic acid (PA)-induced hepatic injury in calf hepatocytes and found that PA could inhibit the gluconeogenic capacity of calf hepatocytes by suppressing the expression of gluconeogenic genes, inhibiting mTORC1, and promoting the activity of mTORC2 (P < 0.01). In contrast, NaP provided protection to calf hepatocytes by counteracting the inhibitory effect of PA on the gluconeogenic capacity of calf hepatocytes (P < 0.05). Collectively, these findings indicate that NaP enhances the gluconeogenic capacity of calf hepatocytes by regulating the mTOR pathway activity. Thus, in addition to improving the glucose production potential, propionate may have therapeutic potential for the treatment of hepatic injury in dairy cows.

Effects of natural and artificial restoration on plant community characteristics of alpine cutting blank in Western Sichuan, China.

To investigate the plant community characteristics of alpine cutting blanks under different restoration approaches, we conducted a field survey on cutting blanks experienced either natural restoration (40 years) or artificial restoration (30, 40 and 50 years) in western Sichuan, with natural forests as the reference. Our results showed that after 40 years natural succession, cutting blank was replaced by the secondary shrub of Spiraea alpina, while artificial restoration plantation was dominated by Picea likiangensis var. rubescens. The similarity indices between these communities and natural forests were low (0.19) and medium (0.28-0.49), respectively. Cutting blank through natural and artificial restoration had lower species diversity in the shrub layer but higher diversity in the herb layer than that of natural forests. With the increases of recovery time, total cross-sectional area at breast height, wood volume, index of species diameter class distribution, diversity indices, and similarity indices between plantations and natural forests gradually increased, while stand density gradually decreased. Compared with natural forests, plantations were facing with problems including high stand density, unreasonable structure, pure stands of cohorts and poor regeneration.

[Phylogenetic structure of Abies georgei var. smithii community at different spatial scales in Sygera Mountains of Tibet, China]. / 不同空间尺度西藏色季拉山急尖长苞冷杉群落谱系结构特征.

We analyzed the phylogenetic structure of trees within six diameter classes (1-2, 2-4, 4-7, 7-11, 11-16, >16 cm) in quadrats with different size of 5 m×5 m,10 m×10 m, 20 m×20 m, 50 m×50 m, 100 m×100 m in a Abies georgei var. smithii community in a 4 hm2 stem-mapping plot located in subalpine dark coniferous forest of Sygera Mountains, southeast Tibet. In various spatial scales, both net relatedness index (NRI) and nearest taxon index (NTI) of the community were larger than zero, indicating a clustered phylogenetic structure with the largest clustering intensity at small spatial scale (5 m×5 m). Community of small-size classes were phylogenetically clustering. In large-size classes (DBH>7 cm) phylogenetic over dispersion became more common, with dispersion increased with increasing tree size under all spatial scales. The intensity of phylogenetic clustering in young trees increased with increasing spatial scales, while the intensity of over dispersion in large trees (DBH>7 cm) increased with spatial scale. Our results suggested that environmental filtering in small-size trees and competitive exclusion in large-size trees might be the main ecological processes driving community assembly in this region.

[Monitoring of seasonal variation of vegetation cover and evaluation of biological-control factor in orchards of China].

Biological-control factor (B) can quantitatively reflect the effect of vegetation on soil erosion. Vertical photography method was used to monitor the seasonal changes of orchard coverage in 18 small watersheds, covering all five water erosion zones in China. The canopy coverage and ground green coverage were then calculated, and the B values were estimated. The result indicated that the orchard canopy coverage varied with season and distributed with a bell shape. The trend of ground green coverage and total coverage changed with season and was affected by the land management. For the orchard where the land surface was not treated and the weeds could grow freely, the distribution of the green coverage season change for all five soil erosion zones had a bell shape. The total coverage in the Northwest Loess Plateau area changed with season with a bell shape as well. The total coverage in the other four areas did not vary with the season and almost kept constant. For the orchard where land surface was cleaned up from time to time, the green coverage and total coverage in all five water erosion areas irregularly varied with season. The average B value of orchards in Northeast black soil area was the minimum with a value of 0.0006, while that in the Northwest Loess Plateau area was the maximum (0.1212). The average orchard B values in the Northern rocky earthy area, the Southern red soil area and the Southwest rocky earthy area were not significantly different and were 0.0548, 0.0627 and 0.0639, respectively.

[Spatial point pattern analysis of Abies georgei var. smithii in forest of Sygera Mountains in southeast Tibet, China].

In this study, based on a 4 hm2 stem-mapping plot, we analyzed spatial distributions of Abies georgei var. smithii, the dominant species in forest of Sygera Mountains in southeast Tibet, China. Pair-correlation function was used to characterize univariate spatial point patterns of three size classes of the population and bivariate spatial patterns between those and different sizes of dead wood. A. georgei var. smithii population was characterized by reverse J-shaped DBH distribution, indicating an increasing population. Saplings of the population were spatially obviously aggregated at the small scales (0-7 m), and mid-sized trees and large-sized trees of the population were randomly or uniformly distributed. The aggregation intensities of A. georgei var. smithii decreased with the increasing diameter classes and spatial scales. Saplings and mid-sized trees were significantly and negatively associated with large-sized trees at the small scales (0-35 and 0-30 m), but the associations reversed at the large scales (45-100 and 80-100 m). In addition, with the increasing age difference between diameter classes of the population, the intensities of positive or negative correlations increased. Spatial associations between saplings and dead large-sized trees, and between mid-sized trees and dead large-sized trees were negative at the small scales (0-34 and 5-27 m), but positive at the large scales (49-100 and 73-100 m). This suggested that released niche space due to dead large-sized trees is not enough to weaken their negative impacts on saplings. We concluded that self-thinning effect and Janzen-Connell hypothesis may be the main mechanisms for the spatial pattern formation of A. georgei var. smithii population.

[Phenolic compounds isolated from rhizoma of Aster tataricus].

OBJECTIVE: To study the chemical constituents in root and rhizome of Aster tataricus. METHODS: Compounds were isolated and purified by silica gel and sephadex LH-20 column chromatography. Their structures were identified by physicochemical properties and spectral analysis. RESULT: Nine compounds were isolated and identified as quercetin (I), kaemferol (II), emodin (III), chrysophanol (IV), physcion (V), benzoic acid (VI), p-hydroxy-bezoic acid (VII), E-caffeic acid (VIII), E-ferulic acid hexacosyl ester (IX). CONCLUSION: Compounds IV, V, VI, VII, VIII, IX were isolated from A. tataricus for the first time.

[Determination of shionone in Radix Asteris by HPLC].

OBJECTIVE: To determine the content of shionone in Radix Aster from several different locations and markets. METHOD: The HPLC analysis was used to determine shionone directly, using Polaris C18 column and acetonitrile as the mobile phase with a flow rate of 1.0 mL.min-1, and the UV detection wavelength was 200 nm. RESULT AND CONCLUSION: The content of shionone was from 0.06% to 0.18%, depending on different locations and markets.

[The effect of human placenta-derived mesenchymal stem cells on cord blood CD8(+);T cells activation, cellcycle and secretion of IL-17].

AIM: To study the effect of human placenta-derived mesenchymal stem cells (hPMSCs) on cord blood CD8(+);T cell activation, cell cycle and secretion of IL-17, and to provide the theoretical basis for it application in the cell-based therapies. METHODS: hPMSCs were isolated from mature placenta by the method of digestion. Then hPMSCs were cultured, expanded in vitro, and were used in test after the third passage. CD8(+);T cells were sorted from cord blood with immunomagetic beads. FCM was used to analyze the expression of early activation phenotype, cell cycle of cord blood CD8(+);T cells and cytokine secretion. RESULTS: CD8(+);T cells stimulated by PHA in the presence of hPMSCs were arrested at G0/G1 phase. The expression of the early activation marker CD25 and CD69 of cord blood CD8(+);T cells was inhibited in the presence of hPMSCs. While, IL-17secretion of cord blood CD8(+);T cells stimulated by PMA was increased. CONCLUSION: hPMSCs can suppress the activation of cord blood CD8(+);T cells by altering T cell cycle; up-regulate the level of IL-17 secreted by cord blood CD8(+);T cells.