[Effects of vegetation and topography features on ecological stoichiometry of soil and soil microbial biomass in the hilly-gully region of the Loess Plateau, China.] / 黄土丘陵区植被与地形特征对土壤和土壤微生物生物量生态化学计量特征的影响.

The objectives of this study were to explore the effects of vegetation type, topographic features and their combined effects on soil microbial biomass stoichiometry, so as to better understand the interaction of soil, soil microbes and nutrient cycling under different vegetation types in the hilly-gully region of the Loess Plateau. Soils from three vegetation zones (forest zone, forest-steppe and steppe) and five slope positions (south/north backslope, south/north shoulder and summit) were chosen and the effects of vegetation types and topography features on soil and C:N:P ratios in soil microbial biomass were investigated in this study. The results showed that, among the five slope positions, the highest concentrations of soil and soil microbial biomass C, N, P were found at the backslope position and the north-facing slope. The effects of vegetation types on soil and soil microbial biomass C, N and P in the two soil layers were significantly different, whereas the effects of slope aspect and positions were only numerically different. As for different soil layers, the topsoil (0-10 cm) was more affected by slope aspect, while the subsoil (10-20 cm) was more influenced by slop position. While the effects of vegetation type on soil C:N, C:P and N:P and soil microbial biomass C:N, C:P were significant, slope aspect and slope position only influenced soil C:P and N:P. Consequently, on the Loess Plateau, the effects of vegetation type on soil and soil microbial biomass C, N, P were stronger than those of the topographic features. The standardized major axis tests showed that C:N:P stoichiometry in soil microbes was well-constrained, especially in the steppe zone. The soil microbial biomass N:P might be used as a useful tool to assess nutrient limitation of ecosystem processes in terrestrial ecosystems. If combined with plant leaf N:P, they could provide more accurate information to estimate the nutrient limitation of fragile ecosystem in hilly-gully region of the Loess Plateau.

[Comparison of effects of Wujia Bugu decoction) and alendronate sodium on protection the bone loss of hindlimb unloaded rats].

OBJECTIVE: To compare the effects of Wujia Bugu decoction and Alendronate sodium on protecting bone and muscle loss of hindlimb unloaded rats lasting three weeks. METHODS: March to May, 2009, 40 male Wistar rats with age of 6-week, were randomized divided to four groups (10 rats in each group): hindlimb unloaded group treated with Chinese medicine (HUC), hindlimb unloaded group treated with alendronate sodium (HUA), control group (CON), as well as hindlimb unloaded group (HU). During the experiment, rats of HUC was given Wujia Bugu decoction (including the Ciwujia, Shudihuang, Huainiuxi, Muli, etc. with the concentration of 0.704 g/ml) 10 ml/kg weight once a day, HUA was given quantitative alendronate sodium slice dissolve suspension (0.9 mg/ml) once a week. CON and HU were given double-distilled water. The experiment lasted 4 weeks,from the second to the forth week, rats in HU, HUC, HUA were hindlimb unloaded. All rats were sacrificed at the fourth weekend, the content of Ca, P and the activation of ALP in serum, Bone mineral density (BMD) of humerus and femurs, Biomechanical property of tibia and humerus, as well as the weight index of biceps and sural muscles were measured. RESULTS: Compared with CON, serum Ca of HU was significantly increased (P < 0.05), BMD, mechanical properties, muscle index of hindlimb were significantly reduce (P < 0.01), the serum Ca of HUA significantly increased (P < 0.05). Serum ALP of HUC was significantly higher than other three groups (P < 0.01). Compared with HU, femoral BMD of HUC and HUA significantly increased, tibial maximum load, maximum deflection and elastic load had increased tendency; calf muscle atrophy of HUC and HUA was alleviate 50% and 12.5% respectively (P > 0.05), humeral BMD had no significant difference, while the maximum deflection (P < 0.01) and elastic deflection (P < 0.05) in humerus of HUA were significantly lower. CONCLUSION: Herbal prescription and alendronate sodium can effectively protect the bone and muscle loss of hindlimb unloaded rats, improve its mechanical structure. Herbal prescription has advantages of relieving mechanical properties change. The effects of Wujia Bugu decoction and alendronate sodium are similar in treating space weightlessness bone loss.

[Effect of a Chinese herbal prescription on collagen I in rat's femur under simulated weightlessness].

OBJECTIVE: To investigate the effect of a Chinese herbal prescription on collagen I in rat's femur under simulated weightlessness. METHODS: Thirty Wistar rats were randomly divided into 3 groups: blank control group (10 rats), tail suspension group (TS, 10 rats), TS with Chinese medicine group (10 rats). Rats in TS with Chinese medicine group took a Chinese herbal prescription (contains Radix Rehmanniae Praeparata, Radix Achyranthis Bidentatae, Radix Astragali, Radix Angelicae Sinensis, Concha Ostreae prepared by acetic acid)by oral administration. After 1 week adaption and 3 weeks tail suspending, rat's left femur was colleced, and collagen I in femur neck was detected by immunohistochemical method. RESULTS: Counts and integral optical density (IOD) of collagen I coloration decreased significantly in TS group (P < 0.001), but no significant change in TS with Chinese medicine group (P > 0.05), as compared with control group. CONCLUSION: Generation of collagen I become weaken under simulated weightlessness, while the Chinese herbal prescription is effective to prevent the change, thus biochemistry environment of bone calcium deposition may be improved by this Chinese herbal prescription under simulated weightlessness.