28 research outputs found

    Soil organic carbon dynamics under long-term fertilizations in arable land of northern China

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    Soil carbon sequestration is a complex process influenced by agricultural practices, climate and soil conditions. This paper reports a study of long-term fertilization impacts on soil organic carbon (SOC) dynamic from six long-term experiments. The experiment sites are located from warm-temperate zone with a double-cropping system of corn (Zea mays L.) - wheat (Triticum Aestivium L.) rotation, to mild-temperate zones with mono-cropping systems of continuous corn, or a three-year rotation of corn-wheat-wheat. Mineral fertilizer applications result in an increasing trend in SOC except in the arid and semi-arid areas with the mono-cropping systems. Additional manure application is important to maintain SOC level in the arid and semi-arid areas. Carbon conversion rate is significant lower in the warm-temperate zone with double cropping system (6.8%-7.7%) than that in the mild-temperate areas with mono-cropping systems (15.8%-31.0%). The conversion rate is significantly correlated with annual precipitation and active accumulative temperature, i.e., higher conversion rate under lower precipitation and/or temperature conditions. Moreover, soil high in clay content has higher conversion rate than soils low in clay content. Soil carbon sequestration rate ranges from 0.07 to 1.461 t ha(-1) year(-1) in the upland of northern China. There is significantly linear correlation between soil carbon sequestration and carbon input at most sites, indicating that these soils are not carbon-saturated thus have potential to migrate more CO2 from atmosphere

    Expression of the novel gene embryo implantation factor 2 (EMO2) in the mouse uterus at the implantation sites

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    Objective: The aim of this study was to identify a novel implantation-related molecule and to examine EMO2 expression in the mouse uterus during the peri-implantation period. Design: Experimental study. Setting: Research laboratory. Animal(S): Adult ICR mice aged 6-8 weeks. Intervention(S): Adult female mice were mated with fertile males to achieve pregnancy. Implantation was delayed by ovariectomizing pregnant mice on day 4 and administering P during days 5-7; implantation was then initiated by administering E-2. Pseudopregnant mice were obtained by mating females with vasectomized males. Main Outcome Measure(s): The tissue distribution of EMO2 mRNA was detected by reverse transcriptase-polymerase chain reaction, and the uterine expression pattern of the EMO2 protein was determined by immunohistochemistry. Result(s): The full cDNA sequence of EMO2 was registered in GenBank (AY372183). EMO2 mRNA expression was observed in all mouse tissues tested. The expression of the EMO2 protein was predominately localized in decidual cells at the implantation site during days 5-6 of pregnancy, and its expression was induced by the active blastocyst and artificially induced decidualization. Conclusion(s): Our data indicate that EMO2 may play a key role in the mouse embryo implantation process. (Fertil Steril (R) 2009;91:2116-22. (C)2009 by American Society for Reproductive Medicine.)National Basic Research Program of China [2006CB504005]; National Natural Science Foundation of China [30672247
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