ABSTRACT
Based on the daily meteorological data of 124 agricultural meteorological sites during 1977-2010 in Yunnan Province, using recommended Penman-Monteith formula by FAO, water requirement and irrigation requirement index in the growth period of flue-cured tobacco were calculated to analyze their spatial and temporal characteristics and change patterns. The results showed that water requirements of flue-cured tobacco in root extending, vigorous, mature periods and field growth period during 1977-2010 were 76.73-174.73, 247.50-386.64, 180.28-258.14 and 528.18-764.08 mm, respectively, and the water requirement of vigorous period was the highest. The average irrigation demand index of each period was -0.02, 0.38, 0.17 and 0.26, respectively. Effective precipitation could meet the demand of flue-cured tobacco in root extending period. Water requirement of flue-cured tobacco in Yunnan Province decreased annually, and the rates of water requirement under the climate change trend in the four periods abovementioned were -12. 42, -21.46, -7.17 and -47.15 mm . (10 a)-1, respectively. The smallest irrigation demand index was observed in Dehong, and the largest in Diqing. The irrigation demand indexes of Dehong, Xishuangbanna and Puer regions were negative in flue-cured tobacco field growth period. The reference crop evapotranspiration, water requirement and effective precipitation decreased, but the irrigation requirement and irrigation requirement index increased with the increase of latitude. The effective precipitation decreased, but the irrigation requirement and irrigation requirement index increased with the increase of altitude.
Subject(s)
Agricultural Irrigation , Nicotiana/physiology , Water/physiology , Altitude , China , Climate Change , Plant Roots/growth & development , Spatio-Temporal AnalysisABSTRACT
<p><b>BACKGROUND</b>The development of regenerative therapies using derivatives of embryonic stem (ES) cells would be facilitated by a non-invasive method to monitor transplanted cells in vivo, for example, magnetic resonance imaging of cells labeled with superparamagnetic iron oxide (SPIO) nanoparticles. Although ES cells have been labeled with SPIO particles, the potential adverse effects of the label have not been fully examined. The objective of this study was to determine whether SPIO labeling affects murine ES cell viability, proliferation, or ability to differentiate into functional endothelial cells (ECs).</p><p><b>METHODS</b>Cross-linked iron oxide (CLIO, an SPIO) was conjugated with human immunodeficiency virus transactivator of transcription (HIV-Tat) peptides, and murine ES cells were labeled with either CLIO-Tat, CLIO, or HIV-Tat. After labeling, ES cells were cultured for 4 days and Flk-1(+) ES cells identified and sorted by immunocytochemistry and fluorescence activated cell sorting (FACS). Flk-1(+) cells were replated on fibronectin-coated dishes, and ECs were obtained by culturing these for 4 weeks in endothelial cell growth medium supplemented with vascular endothelial growth factor (VEGF). ES cell viability was determined using trypan blue exclusion, and the proportion of SPIO(+) cells was evaluated using Prussian blue staining and transmission electron microscopy. After differentiation, the behavior and phenotype of ECs were analyzed by reverse transcription-polymerase chain reaction, flow cytometry, immunocytochemistry, DiI-labeled acetylated low-density lipoprotein (AcLDL) uptake, and Matrigel tube formation assay.</p><p><b>RESULTS</b>CLIO-Tat was a highly effective label for ES cells, with > 96% of cells incorporating the particles, and it did not alter the viability of the labeled cells. ECs derived from CLIO-Tat(+) ES cells were very similar to murine aortic ECs in their morphology, expression of endothelial cell markers, ability to form vascular-like channels, and scavenging of AcLDL from the culture medium.</p><p><b>CONCLUSIONS</b>CLIO-Tat is a highly effective label for ES cells and does not adversely affect cell viability, differentiation, or behavior. CLIO-Tat could be a useful marker for the non-invasive monitoring of transplanted stem cells.</p>
