lmmunofluorescence microscopy and in situ hybridization were used to examine the expression of genes encoding C4 photosynthetic enzymes during early leaf development in the C4 dicotyledonous grain plant amaranth. During early developmental stages, the chloroplast-encoded large subunit and nuclear-encoded small subunit genes of ribulose-1,8bisphosphate carboxylase/oxygenase (RuBPCase) were expressed in both bundle sheath and mesophyll cells in a C3-type pattern. The RuBPCase proteins and mRNAs became specifically localized to bundle sheath cells in the characteristic Cctype pattern as the leaves continued to expand and develop. Changes in the localization of the RuBPCase proteins corresponded closely with changes in the localization of their mRNAs, indicating that the cell-specific expression of genes encoding RuBPCase is controlled, at least in part, at the level of transcript accumulation. Genes encoding pyruvate orthophosphate dikinase were expressed specifically in mesophyll cells at all developmental stages examined. lmmunolocalization with antibodies raised against phosphoenolpyruvate carboxylase (PEPCase) showed that this enzyme is present only in leaf mesophyll cells, even though RNA sequences with homology to PEPCase gene sequences were present in both bundle sheath and mesophyll cells. These results suggest that the regulation of genes encoding PEPCase in amaranth is complex and could involve the differential expression of divergent PEPCase genes or possibly regulation at the post-transcriptional level.
The volatility of a stock returns can be decomposed into market and firm-specific volatility, with the former commonly known as systematic risk and the later as idiosyncratic risk. This study examines the relevance of idiosyncratic risk in explaining the monthly cross-sectional returns of REIT stocks. Contrary to the CAPM theory, a significant positive relationship is found between idiosyncratic volatility and the cross-sectional returns. This suggests that firm-specific risk matters in REIT pricing. The regression results further show that once idiosyncratic risk is controlled for in the asset-pricing model, the size and book-to-market equity ratio factors ceased to be significant. The explanatory power of the momentum effect remains robust in the presence of idiosyncratic risk. Copyright Springer Science+Business Media, LLC 2009Idiosyncratic risk, Asset pricing, REIT stocks,
Six-arm star-shaped poly(e-caprolactone) (sPCL) was successfully synthesized via the ring-opening polymerization of e-caprolactone with a commercial dipentaerythritol as the initiator and stannous octoate (SnOct 2 ) as the catalyst in bulk at 120 8C. The effects of the molar ratios of both the monomer to the initiator and the monomer to the catalyst on the molecular weight of the polymer were investigated in detail. The molecular weight of the polymer linearly increased with the molar ratio of the monomer to the initiator, and the molecular weight distribution was very low (weight-average molecular weight/number-average molecular weight ¼ 1.05-1.24). However, the molar ratio of the monomer to the catalyst had no apparent influence on the molecular weight of the polymer. Differential scanning calorimetry analysis indicated that the maximal melting point, cold crystallization temperature, and degree of crystallinity of the sPCL polymers increased with increasing molecular weight, and crystallinities of different sizes and imperfect crystallization possibly did not exist in the sPCL polymers. Furthermore, polarized optical microscopy analysis indicated that the crystallization rate of the polymers was in the order of linear poly(e-caprolactone) (LPCL) > sPCL5 > sPCL1 (sPCL5 had a higher molecular weight than both sPCL1 and LPCL, which had similar molecular weights). Both LPCL and sPCL5 exhibited a good spherulitic morphology with apparent Maltese cross patterns, whereas sPCL1 showed a poor spherulitic morphology. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: [5449][5450][5451][5452][5453][5454][5455][5456][5457] 2005
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