Dazhou Chen

Publications (4)15.94 Total impact

• Source

  Available from: Kang Chong

  Article: Overexpression of a homopeptide repeat-containing bHLH protein gene (OrbHLH001) from Dongxiang Wild Rice confers freezing and salt tolerance in transgenic Arabidopsis.

  Fei Li, Siyi Guo, Yuan Zhao, Dazhou Chen, Kang Chong, Yunyuan Xu
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  ABSTRACT: Dongxiang Wild Rice (Oryza rufipogon) is the northernmost wild rice in the world known to date and has extremely high cold tolerance and many other adversity-resistant properties. To identify the genes responsible for the high stress tolerance, we isolated and characterized a basic helix-loop-helix (bHLH) protein gene OrbHLH001 from Dongxiang Wild Rice. The gene encodes an ICE1-like protein containing multiple homopeptide repeats. Expression of OrbHLH001 is induced by salt stress and is predominant in the shoots of wild rice seedlings. Overexpression of OrbHLH001 enhanced the tolerance to freezing and salt stresses in transgenic Arabidopsis. Examination of the expression of cold-responsive genes in transgenic Arabidopsis showed that the function of OrbHLH001 differs from that of ICE1 and is independent of a CBF/DREB1 cold-response pathway.
  Plant Cell Reports 09/2010; 29(9):977-86. · 2.27 Impact Factor
• Article: Transport of semivolatile organic compounds to the Tibetan plateau: spatial and temporal variation in air concentrations in mountainous Western Sichuan, China.

  Wenjie Liu, Dazhou Chen, Xiande Liu, Xiaoyan Zheng, Wen Yang, John N Westgate, Frank Wania
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  ABSTRACT: The distribution of organochlorine pesticides and polychlorinated biphenyls in air along an altitudinal transect on Balang Mountain in western China was measured by deploying XAD-2 resin based passive air samplers in duplicate at seven sites with elevations ranging from 1242 to 4485 m above sea level for five consecutive six-month periods between 2005 and 2008. Analyzed by gas chromatography-high resolution mass spectrometry, concentrations of hexachlorobenzene were highest, followed by hexachlorocyclohexanes, DDT-related compounds and PCB congeners 28 and 52. Except for hexachlorobenzene, which had largely uniform concentrations in space and time, there were clear seasonal variations with concentrations in summer being higher than in winter. With a few exceptions, concentrations that vary little with altitude suggest that the presence of these chemicals in the area is almost entirely due to atmospheric transport, most likely from the Chengdu plain. This is supported by similarities in the relative abundance of different compounds and in the differences between summer and winter concentrations measured in the city of Chengdu and in the mountains. Furthermore, air mass trajectories during the sampling period often originate to the East, passing over the Western part of the Sichuan basin, including the Chengdu plain, prior to arriving at the sampling sites. Higher summer time values in the mountains are due to more contaminated air being blown into the region, presumably due either to higher pesticide usage in summer or due to higher temperatures leading to higher evaporation in source regions. Air and soil from the region are in equilibrium with respect to alpha-HCH, gamma-HCH, and HCB, whereas a situation of net deposition prevails for p,p'-DDE and p,p'-DDT.
  Environmental Science and Technology 02/2010; 44(5):1559-65. · 5.23 Impact Factor
• Article: Spatial and seasonal variations of organochlorine compounds in air on an urban-rural transect across Tianjin, China.

  Xiaoyan Zheng, Dazhou Chen, Xiande Liu, Qunfang Zhou, Yue Liu, Wen Yang, Guibin Jiang
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  ABSTRACT: The spatial and seasonal variations of atmospheric organochlorine compounds (OCs) concentrations was investigated at six sites on an urban-rural transect in Tianjin, China from July 2006 to June 2008 using XAD-based passive air samplers. The samplers were deployed for six time periods. Hexachlorocyclohexanes (HCHs) air concentrations were highest at Tanggu and Tuanbowa and decreased dramatically further away from these two sites. The maximum proportion of beta-HCH compared to SigmaHCHs (12.1-32.2%) was found in Hangu, suggesting its persistence. The alpha/gamma-HCH ratio was between 1.26 and 5.79 which signified the combined influence of technical HCHs and lindane. Dichlorodiphenyltrichloroethane related compounds (DDTs) were higher at Hangu compared with other sites which was attributed to its continuing production there. Low p,p'-DDE/p,p'-DDT in Hangu and Tanggu were found, reflecting the fresh input of DDTs while the relatively high o,p'-DDT/p,p'-DDT ratios indicated the agricultural application of dicofol. Polychlorinated biphenyls distribution elucidated that the urban area could be their emission source. Hexachlorobenzene, with the highest concentrations in Tanggu, showed the smallest industrial/urban-rural gradient ( approximately 4-9 times) than those of other chemicals (approximately 17-49 for SigmaHCHs, approximately 10-77 for SigmaDDTs), but comparable with PCBs (PCB28 and PCB52) (approximately 3-10). Seasonal variations of OCPs were featured by higher concentration in spring and summer and lower in winter. This was likely associated with (i) their temperature-driven re-volatilization and (ii) application of dicofol in late spring and summer and DDT-containing antifouling paints for fishing ships in summer. However seasonality of PCBs concentrations was site-specific on the Tianjin scale.
  Chemosphere 11/2009; 78(2):92-8. · 3.21 Impact Factor
• Article: Cold-trapping of persistent organic pollutants in the mountain soils of western Sichuan, China.

  Dazhou Chen, Wenjie Liu, Xiande Liu, John N Westgate, Frank Wania
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  ABSTRACT: In the Chinese province of Sichuan steep mountains rise from the very densely populated and intensely cultivated Chengdu basin more than 4000 elevational meters to the Tibetan Plateau. This steep physical gradient is exceptionally well suited to investigate the transport of persistent pesticides and other organic contaminants from low to high elevations. In spring and autumn 2006, 25 soil samples were taken at five elevations ranging from 2636 to 4479 m along the East-facing slope of Balang Mountain in Wolong Nature Reserve. Analysis of soil extracts was done by gas chromatography-high resolution mass spectrometry. Whereas hexachlorobenzene (HCB), hexachlorocyclohexanes (HCH), and dichlorodibenzotrichloroethane and its degradation products (DDTs) were present at levels of a few ng/g, only two light PCB congeners were detected at levels below 1 ng/g in soil. Soil concentration for all analytes increased significantly and exponentially with altitude. The rate of concentration increase, expressed quantitatively through the slope of the linear regression between the logarithm of the concentrations and altitude, increases along the sequence HCB < PCB < HCH < or = DDT. This trend is consistent with, and therefore lends additional observational support to, a mountain cold-trapping mechanism based on the temperature dependence of precipitation scavenging.
  Environmental Science and Technology 01/2009; 42(24):9086-91. · 5.23 Impact Factor