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Zacharia S. Cheruvallath Patrick D. Wheeler Douglas L. Cole Vasulinga T. Ravikumar 《Nucleosides, nucleotides & nucleic acids》2013,32(3):485-492
Abstract Investigations into the use of phenylacetyl disulfide (PADS) as an efficient sulfur transfer agent in the solid phase synthesis of oligodeoxyribonucleotide phosphorothioates showed that under suitable solvent conditions, this relatively inexpensive reagent rapidly and efficiently sulfurizes internucleotide phosphite linkages. 相似文献
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Achim H. Krotz Zacharia S. Cheruvallath Douglas L. Cole Vasulinga T. Ravikumar 《Nucleosides, nucleotides & nucleic acids》2013,32(12):2335-2338
Abstract Deprotection of 2-(diphenylmethylsilyl)ethyl (DPSE) protected (O,O,O)-and (O,O,S)-trialkyl phosphorothioates with tetrabutylammonium fluoride affords the corresponding phosphorothioate. Formation of phosphodiester linkages is not observed. 相似文献
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We have developed a gas chromatography/mass spectrometry (GC/MS) assay to measure 17beta-estradiol (E) and its biologically active metabolites 2-hydroxyestradiol (2OHE) and 4-hydroxyestradiol (4OHE), and 2-methoxyestradiol (2MEOE) and 4-methoxyestradiol (4MEOE) in rat plasma. All analytes are well separated and show a linear relationship between concentration (0.25-5 pg/microl) and signal, and coefficients of variation (CVs) are low. Intra-assay CV for the lowest quality control samples (QCs) (0.375 pg/microl) were on average for 17beta-estradiol 20.5%, for 2-hydroxyestradiol 15.6%, for 4-hydroxyestradiol 16.5%, for 2-methoxyestradiol 16.5%, and for 4-methoxyestradiol 11.5%. The inter-assay CVs for the lowest QCs were for 17beta-estradiol 12.1%, for 2-hydroxyestradiol 7.1%, for 4-hydroxyestradiol 15.5%, for 2-methoxyestradiol 16.7%, and for 4-methoxyestradiol 9.7%. The highest sensitivity for this assay was observed for hydroxyestradiols followed by the methoxyestradiols and 17beta-estradiol. In summary, we describe a convenient, sensitive, and specific assay to measure 17beta-estradiol and its biologically active metabolites. 相似文献
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Ophioglossum petiolatum . Unlike Angiopteris (Marattiales), which is monoplastidic, Ophioglossum undergoes polyplastidic meiosis like members of the fern-seed plant clade. The meiotic spindle is distinctly multipolar in
origin and is consolidated into a bipolar spindle that is variously twisted and curved to accommodate the large number of
chromosomes. Although a phragmoplast forms after first meiosis, no wall is deposited. Instead, an organelle band consisting
of intermingled plastids and mitochondria is formed in the equatorial region between the dyad domains. Following second meiosis,
a complex of phragmoplasts forms among sister and non-sister nuclei. Cell plates are deposited first between sister nuclei
and then in the region of the organelle band resulting in a tetrad of spores each with a equal allotment of organelles.
Received 30 January 2001/ Accepted in revised form 24 April 2001 相似文献
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A flux analysis of glucose metabolism in the filamentous fungus Rhizopus oryzae was achieved using a specific radioactivity curve-matching program, TFLUX. Glycolytic and tricarboxylic acid cycle intermediates labeled through the addition of extracellular [U-14C]glucose were isolated and purified for specific radioactivity determinations. This information, together with pool sizes and the rates of glucose utilization and end product production, provided input for flux maps of the metabolic network under two different experimental conditions. Based upon the flux analysis of this system, a mutant of R. oryzae with higher lactate and lower ethanol yields than the parent was sought for and found. 相似文献