[Biomass allocations and their response to environmental factors for grass species in an arid-hot valley]. / å¹²çƒ­æ²³è°·è‰æœ¬æ¤ç‰©ç”Ÿç‰©é‡åˆ†é åŠå ¶å¯¹çŽ¯å¢ƒå› å­çš„å“åº”.

The effects of water supply frequency, nutrient addition and clipping on biomass allocations among roots, stems and leaves as well as their allometric scaling relationships for six grass species from an arid-hot valley were investigated. The results showed that the fraction of leaf biomass significantly increased from 25.1% to 31.2% and the faction of stem biomass decreased from 43.7% to 34.2% under clipping treatment. Fertilization significantly decreased the faction of root biomass from 34.0% to 30.8%. Water treatments had no significant effect on biomass allocations. Species identity significantly affected biomass allocations among roots, stems and leaves. Species adapted to infertile soils allocated more biomass into leaves and roots and less into stems. There were significant interactions between species and environmental factors, suggesting that the effects of environmental factors on biomass allocations differed among species. Allometric constants and scaling exponents of leaf-stem for species adapted to infertile soils were greater than those for other species. Allometric constants and scaling exponents of stem-root for species adapted to infertile soils were lower than those for other species. In total, nutrient addition significantly increased allometric constants of leaf-stem and leaf-root while clipping significantly reduced scaling exponents of stem-root. The frequency of water supply had no significant effects on the allometric scaling relationships among different organs. The effects of environmental factors on the allometric scaling relationships between different organs differed among species. The differences in biomass allocations and their responses to environmental factors among different species might affect plant adaptations to environmental changes.

[Element concentration in leaves and nutrient resorption efficiency on dry-red soil and vertisols in dry and hot valley in Yuanmou, China.] / å ƒè°‹å¹²çƒ­æ²³è°·ç‡¥çº¢åœŸå’Œå˜æ€§åœŸä¸Šæ¤ç‰©å¶ç‰‡çš„å ƒç´ å«é‡åŠå ¶é‡å¸æ”¶æ•ˆçŽ‡.

By performing a pot experiment, the study compared leaf and litter element concentration between the dry-red soil and vertisols, and analyzed the interactive effects of soil types and species on leaf nutrient concentration and nutrient resorption efficiency. The results showed that the soil type significantly affected the concentrations of N, P, Ca, Mg, Cu, Zn, Fe and N:P in leaves as well as the concentrations of N, P, Mn and N:P in leaf litters. Concentrations of N, Mn and N:P in leaves and litters derived from the dry-red soil were significantly higher than those from the vertisols. In contrast, concentrations of P, Ca, Mg, Fe, Cu and Zn in leaves and concentration of P in litters derived from the dry-red soil were significantly lower than those from the vertisols. Leaf N concentration was 34.8% higher, and leaf P concentration was 40.0% lower from the dry-red soil compared with those from the vertisols. N, P and K showed net resorption while the other elements showed accumulating patterns when leaf was senesced. Accumulation of Ca, Mg and Mn of senesced leaves was significantly higher on the dry-red soil than on the vertisols. Species identities only significantly affected leaf N concentration. Interactions of species and soil taxonomy significantly affected nutrient concentration neither in leaves nor in leaf litters, indicating that soil taxonomy influenced plant nutrient concentration in a similar way across multiple species. The influences of soil types on plant element concentration could have further effects on litter decomposition, plant-soil nutrient feedback and biogeochemical cycle in this dry and hot valley.

[Changes of plant leaf N, P, and K concentrations and species dominance in an arid-hot valley after ecosystem restoration].

Taking the arid-hot valley of Jinsha River, Southwest China as the object, a comparative study was made on the plant leaf N, P, and K concentrations and ratios as well as their relationships with species dominance in the restoration area and disturbed area, aimed to understand the effects of ecosystem restoration on the plant leaf stoichoimetric characteristics. Ecosystem restoration decreased the plant leaf N and P concentrations and P/K ratio significantly, but had lesser effects on the plant leaf K concentration. In restoration area, the plant leaf N, P, and K concentrations were averagely 10. 405, 0. 604, and 9. 619 g kg-1, being 16. 9% , 34. 9% , and 4. 7% lower than those in disturbed area, respectively. In restoration area, species dominance was significantly negatively correlated with plant leaf P concentration; while the species dominance in disturbed area had a significant negative correlation with plant leaf K concentration. Ecosystem restoration altered the slope and intercept of the scaling relationships among the plant leaf N, P, and K. No significant differences were observed in the leaf N, P, and K concentrations of the same plant species between restoration area and disturbed area, suggesting that the changes of plant leaf stoichiometric characteristics were mainly driven by the shift of species composition in the plant community.

[IL-18 expression in whole blood cell cultures from active lupus nephritis and the inhibitory effects of FK506, cyclosporin A and dexamethasone].

AIM: To explore the expression of IL-18 in patients with active lupus nephritis(LN) and the inhibitory effects of immunosupressive agents FK506, cyclosporin A (CsA) and dexamethasone(DEX). METHODS: Peripheral blood samples were collected from 16 LN patients and 10 health volunteers and cultured with or without PHA/LPS, PHA/LPS+FK506, PHA/LPS+CsA and PHA/LPS+DEX for 24 hours. The IL-18 level in cultured supernatants and the IL-18 mRNA expression in cultured whole blood cells were detected by ELISA and semi-quantitative RT-PCR respectively, and the inhibitory effects of FK506, CsA and DEX on IL-18 expression were investigated. RESULTS: The expression levels of IL-18 mRNA and its protein in whole blood cell cultures from LN patients were higher than those in normal control group (P<0.01) either spontaneously or after stimulation with LPS/PHA. FK506, CsA and DEX suppressed significantly the expressions of IL-18 mRNA and its protein (P<0.001) in LPS/PHA-stimulated whole blood cell from LN patients. The inhibitory effects of FK506, CsA and DEX on the IL-18 protein expression in LN patients were stronger than that in normal control group (P<0.01 or P<0.05). CONCLUSION: IL-18 may play an important role in the pathogenesis of LN and inhibition of IL-18 production may be an useful way to treat LN.