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27 results on '"Xu, Xiangqin"'

13. The concentration, flux and occurrence process of total phosphorus in Dahuofang reservoir and Suggestions for environmental optimal operation

Author

Li Xinghua, Dai Dan, Xu Xiangqin, Huang Guoxian, Sun Mingdong, Wang Tong, and Yuan Honggang

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

Dahuofang reservoir is one of the most important drinking water sources in Liaoning province, China. Dynamics of total phosphorus (TP) concentration, flux and related retention processes in this reservoir are very important to the water quality management and drinking water safety. Based on the monitoring data of meteorology, hydrology, water quality and sediment from the main stations during 1992-2017, this paper analysed the TP fluxes in the different boundaries and the stocking process in both the overlying water and the active surface sediment layer using the mass balance method. This study revealed the TP accumulation variation in the overlying water and the surface sediment layer and the controlling mechanism of TP concentration in overlying water under different hydrological conditions. The results showed that the combination of flood and dry hydrological rhythms is important to maintain the dynamic balance of TP in the reservoir. Based on these results, to reduce the TP retention rate and accumulated TP in the active surface sediment layer, we put forward suggestions on environmental optimization operations during the early days of large flood and subsequent small flood season by opening the deep flood discharging holes of the reservoir and lowering upstream water level. These results provide an improved understanding and new eyesight of the nutrient control of large reservoirs in the north China.

Published
2018
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21. Effect of Solidago canadensis invasions on soil nematode communities in Hangzhou Bay

Author

Lu Qiang, Xu Xiangqin, Chen Huili, Wang Yingying, and Lin Zhihua

Subjects
Ecology, Soil biodiversity, Soil biology, Plant community, Soil carbon, Biology, Native plant, Solidago canadensis, biology.organism_classification, complex mixtures, Plant ecology, Agronomy, Ecosystem, Ecology, Evolution, Behavior and Systematics, Nature and Landscape Conservation
Abstract

Ecologists are increasingly focusing on the effects of biological invasions on soil biodiversity and ecosystem functioning. We compared soil nematodes under plant communities dominated by invasive Solidago canadensis and native plant Phragmites australis at 6 sites (Zhenhai, Fengxian, Pinghu, Haiyan, Cixi and Hangzhou) in Hangzhou Bay to assess the effects of S. canadensis invasions on soil nematode communities. The total number of genera and diversity of soil nematode did not differ between S. canadensis and P. australis communities. Trophic diversity, most of the proportions of trophic groups and nematode community structure varied between the two plant communities. These results suggested that the invasion of S. canadensis changed soil community structure and functioning in Hangzhou Bay. Compared to P. australis communities, the proportion of fungivores tended to increase in soil under S. canadensis communities, suggesting that the invasion might modify soil nutrient cycling. The proportion of herbivores decreased in soil dominated by S. canadensis, suggesting that the exotic S. canadensis is less vulnerable to parasitic nematodes than the native P. australis. Interactions between plant community type and site were significant for nematode diversity and community structure, which indicated that site was an important factor in determining the impact of the invasive plant on soil fauna. Soil grain composition, soil carbon and soil nitrogen were identified as the most important factors in shaping nematode communities.

Published
2011

27. CXCR4 inhibitor attenuates allergen-induced lung inflammation by down-regulating MMP-9 and ERK1/2.

Author

Chen H, Xu X, Teng J, Cheng S, Bunjhoo H, Cao Y, Liu J, Xie J, Wang C, Xu Y, and Xiong W

Subjects
Allergens, Animals, Asthma enzymology, Asthma immunology, Benzylamines, Bronchi enzymology, Bronchi immunology, Cell Line, Chemokine CXCL12 metabolism, Cyclams, Disease Models, Animal, Down-Regulation, Enzyme Activation, Epithelial Cells enzymology, Epithelial Cells immunology, Female, Humans, Interleukin-13 metabolism, Mice, Inbred BALB C, Ovalbumin, Pneumonia enzymology, Pneumonia immunology, Receptors, CXCR4 immunology, Receptors, CXCR4 metabolism, Signal Transduction drug effects, Time Factors, Anti-Asthmatic Agents pharmacology, Anti-Inflammatory Agents pharmacology, Asthma drug therapy, Bronchi drug effects, Epithelial Cells drug effects, Heterocyclic Compounds pharmacology, Matrix Metalloproteinase 9 metabolism, Mitogen-Activated Protein Kinase 1 metabolism, Mitogen-Activated Protein Kinase 3 metabolism, Pneumonia drug therapy, Receptors, CXCR4 antagonists & inhibitors
Abstract

Chemokine (C-X-C motif) ligand 12 (CXCL12) and its receptor chemokine receptor 4 (CXCR4) have been recognized to play a crucial role in the pathogenesis of bronchial asthma, but the underlying molecular mechanisms are yet to be fully addressed. In the present report we demonstrated that CXCL12/CXCR4 signaling mediates allergic airway inflammation through induction of matrix metalloproteinase 9 (MMP-9) in a murine asthmatic model. We noted that administration of AMD3100, a specific CXCR4 antagonist, significantly attenuated OVA-induced asthmatic responses along with reduced epithelial MMP-9 expression. Our studies in a bronchial epithelial cell line, 16HBE cells, further revealed that CXCL12/CXCR4 signaling synergizes with IL-13 to enhance epithelial MMP-9 expression. Our mechanistic studies demonstrated that CXCL12/CXCR4 enhances epithelial MMP-9 expression by inducing ERK1/2 expression and activation. Together, these studies would bring novel insight into the understanding for the role of CXCL12/CXCR4 signaling in asthmatic responses during the course of bronchial asthma development.

Published
2015

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