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71.
Treatment of 2,5-anhydro-1-bromo-1-deoxy-2,3-O-isopropylidene-1-p-nitrophenylhydrazono-d-ribose with methyl acetylenecarboxylate gave methyl 3-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-1-p-nitrophenylpyrazole- (8) and 5-carboxylate (9). Amidification at C-5 of 8 was easier than at C-4 of 9. Similarly, dimethyl 3-(2,3-O-isopropylidene-β-d-erythrofuranosyl)- 1 - p-nitrophenylpyrazole-4,5-dicarboxylate gave specifically a 5-carbamoyl derivative, the structure of which was established by comparison of the 13C-n.m.r.spectrum with those of a series of glycosylpyrazoles. The correlation between the experimental values of the chemical shifts of the carbon atoms of the pyrazole ring and the values calculated by addition of the contributions of the various groups linked to the ring was better (R 0.98) than the correlations obtained by calculation by the CNDO/2 method of the total electron population (R 0.92) or of the π-electron population of each carbon atom (R 0.85). 相似文献
72.
The manner in which centromere regions of mitotic chromosomes are distributed with respect to the age of their DNA was studied. Cells of the Indian deer, Muntiacus muntjak, were grown in the presence of bromodeoxyuridine (BrdU) for two generations and stained with the fluorescent dye Hoechst 33258. Chromatids containing granddaughter DNA appear dim when compared with those containing grandparental DNA. The frequencies of the various anaphase patterns of bright and dim centromere regions were binomially distributed, indicating random distribution of chromatids with respect to the age of their DNA templates. 相似文献
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Summary Ethidium was found to be taken up by yeast cells in a process that, at certain concentrations has the main following characteristics: a) a substrate is required; b) it presents cooperative kinetics, withn, according to the Hill equation 3; c) ethidium can be concentrated more than 100-fold; d) the uptake is inhibited by Ca2+; e) the uptake of the dye is inhibited by monovalent cations with a selectivity pattern similar to that observed in their transport by yeast; f) ethidium inhibits the uptake of K+, and, at concentrations up to about 250 m produces a competitive inhibition on the uptake of Rb+; and g) ethidium produces the same effects as K+ on respiration and the extrusion of H+. It is concluded that ethidium is taken up by yeast cells in a selective way by the same transport system normally employed for monovalent cation uptake. 相似文献
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Jafar A. Mammadov Wei Chen Ruihua Ren Reetal Pai Wesley Marchione Feyruz Yalçin Hanneke Witsenboer Thomas W. Greene Steven A. Thompson Siva P. Kumpatla 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,121(3):577-588
The duplicated and the highly repetitive nature of the maize genome has historically impeded the development of true single
nucleotide polymorphism (SNP) markers in this crop. Recent advances in genome complexity reduction methods coupled with sequencing-by-synthesis
technologies permit the implementation of efficient genome-wide SNP discovery in maize. In this study, we have applied Complexity
Reduction of Polymorphic Sequences technology (Keygene N.V., Wageningen, The Netherlands) for the identification of informative
SNPs between two genetically distinct maize inbred lines of North and South American origins. This approach resulted in the
discovery of 1,123 putative SNPs representing low and single copy loci. In silico and experimental (Illumina GoldenGate (GG)
assay) validation of putative SNPs resulted in mapping of 604 markers, out of which 188 SNPs represented 43 haplotype blocks
distributed across all ten chromosomes. We have determined and clearly stated a specific combination of stringent criteria
(>0.3 minor allele frequency, >0.8 GenTrainScore and >0.5 Chi_test100 score) necessary for the identification of highly polymorphic
and genetically stable SNP markers. Due to these criteria, we identified a subset of 120 high-quality SNP markers to leverage
in GG assay-based marker-assisted selection projects. A total of 32 high-quality SNPs represented 21 haplotypes out of 43
identified in this study. The information on the selection criteria of highly polymorphic SNPs in a complex genome such as
maize and the public availability of these SNP assays will be of great value for the maize molecular genetics and breeding
community. 相似文献
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Bruno Kieffer Patrice Koehl Serge Plaue Jean-François Lefèvre 《Journal of biomolecular NMR》1993,3(1):91-112
Summary We have investigated the dynamics and structural behaviour of two antigenic peptides using 1H NMR. The two cyclic peptides mimic the antigenic site A of influenza haemagglutinin protein; they only differ in the way they were cyclized and in the size of their respective linkers. Homonuclear relaxation parameters extracted from a complete NOE matrix were interpreted in terms of local dynamics. A set of distance constraints was deduced from these parameters which allowed 3D models to be constructed using distance geometry. NOE back-calculation was used to check the validity of the final models. Strong variations of internal motion amplitude have been found in both peptides along their backbone. Motions with high amplitudes have been localized in the Gly-Pro-Gly sequence which forms a -turn in both structures.Abbreviations DSS
3-(trimethylsilyl)-1-propanesulfonic acid
- D-loop
aspartic acid loop
- ELISA
enzyme-linked immunoabsorbent assay
- f.i.d
free induction decay
- HOHAHA
homonuclear Hartmann-Hahn spectroscopy
- HPLC
high pressure liquid chromatography
- K-loop
lysine loop
- NMR
nuclear magnetic resonance
- NOE
nuclear Overhauser enhancement
- NOESY
nuclear Overhauser enhancement spectroscopy
- r.m.s.d.
root-mean-square deviation of atomic positions 相似文献