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191.
Three monofluorocinnamoylchymotrypsins have been examined at pH 4 by fluorine NMR spectroscopy. Protein-induced fluorine chemical shifts are quite large (~7 ppm) when fluorine is present at the para position but nearly zero for ortho fluorine. The shifts roughly parallel those observed in complexes formed between the enzyme and the analogous N-acetylfluorophenylalanines, suggesting a similarity in molecular environment for the aromatic ring in both systems. Little correlation is found, however, between the shifts for the acylenzymes and those of the corresponding enzyme-cinnamate complexes, indicating that the environment for the aromatic ring in the complexes is dissimilar from that experienced by the aromatic group in the acylated enzyme. Solvent isotope effects () on the fluorine chemical shifts for the fluorocinnamoylchymotrypsins are small and downfield. Fluorine NMR observations suggest that the presence of the fluorocinnamoyl group greatly stabilizes the enzyme toward denaturation in 8 m urea. 相似文献
192.
Bayesian analysis of factorial experiments by mixture modelling 总被引:3,自引:0,他引:3
193.
194.
Bart Janssen Julian Sampson Mieke van der Est Wout Deelen Senno Verhoef Ian Daniels Arjenne Hesseling Phillip Brook-Carter Mark Nellist Dick Lindhout Lodewijk Sandkuijl Dicky Halley 《Human genetics》1994,94(4):437-440
Tuberous sclerosis (TSC) is a heterogeneous trait. Since 1990, linkage studies have yielded putative TSC loci on chromosomes 9, 11, 12 and 16. Our current analysis, performed on 14 Dutch and British families, reveals only evidence for loci on chromosome 9q34 (TSC1) and chromosome 16p13 (TSC2). We have found no indication for a third locus for TSC, linked or unlinked to either of these chromosomal regions. The majority of our families shows linkage to chromosome 9. We have refined the candidate region for TSC1 to a region of approximately 5 cM between ABL and ABO. 相似文献
195.
The endogenous mechanism that determines vertebrate body length is unknown but must involve loss of chordo-neural-hinge (CNH)/axial stem cells and mesoderm progenitors in the tailbud. In early embryos, Fibroblast growth factor (FGF) maintains a cell pool that progressively generates the body and differentiation onset is driven by retinoid repression of FGF signalling. This raises the possibility that FGF maintains key tailbud cell populations and that rising retinoid activity underlies cessation of body axis elongation. Here we show that sudden loss of the mesodermal gene (Brachyury) from CNH and the mesoderm progenitor domain correlates with FGF signalling decline in the late chick tailbud. This is accompanied by expansion of neural gene expression and a similar change in cell fate markers is apparent in the human tailbud. Fate mapping of chick tailbud further revealed that spread of neural gene expression results from continued ingression of CNH-derived cells into the position of the mesoderm progenitor domain. Using gain and loss of function approaches in vitro and in vivo, we then show that attenuation of FGF/Erk signalling mediates this loss of Brachyury upstream of Wnt signalling, while high-level FGF maintains Brachyury and can induce ectopic CNH-like cell foci. We further demonstrate a rise in endogenous retinoid signalling in the tailbud and show that here FGF no longer opposes retinoid synthesis and activity. Furthermore, reduction of retinoid signalling at late stages elevated FGF activity and ectopically maintained mesodermal gene expression, implicating endogenous retinoid signalling in loss of mesoderm identity. Finally, axis termination is concluded by local cell death, which is reduced by blocking retinoid signalling, but involves an FGFR-independent mechanism. We propose that cessation of body elongation involves loss of FGF-dependent mesoderm identity in late stage tailbud and provide evidence that rising endogenous retinoid activity mediates this step and ultimately promotes cell death in chick tailbud. 相似文献
196.
Lövei GL Lewinsohn TM Dirzo R Elhassan EF Ezcurra E Freire CA Gui FR Halley JM Tibazarwa JM Jiang MX Katebaka R Kinyamario J Kymanywa S Liu FQ Liu SS Liu WX Liu YQ Lu BR Minot EO Qiang S Qiu BL Shen H Soberon J Sujii ER Tang JW Uludag A Vitule JR Wan FH Wang FH Yang GQ Zhang XY You MS;Biological Invasions in Megadiverse Regions Network 《Trends in ecology & evolution》2012,27(1):2-3
197.
Identification and molecular mapping of two QTLs with major effects for resistance to Fusarium head blight in wheat 总被引:1,自引:0,他引:1
Chu C Niu Z Zhong S Chao S Friesen TL Halley S Elias EM Dong Y Faris JD Xu SS 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,123(7):1107-1119
Fusarium head blight (FHB) is a devastating disease of wheat worldwide. Novel sources of resistance are critical for improving
FHB resistance levels in wheat. From a large-scale evaluation of germplasm for reactions to FHB, we identified one wheat accession
(PI 277012) that consistently showed a high level of resistance in both greenhouse and field experiments. To characterize
the FHB resistance in this accession, we developed a doubled haploid (DH) mapping population consisting of 130 lines from
the cross between PI 277012 and the hard red spring wheat cultivar ‘Grandin’. The DH population was then evaluated for reactions
to FHB in three greenhouse seasons and five field environments. Based on a linkage map that consisted of 340 SSR markers spanning
2,703 cM of genetic distance, two major quantitative trait loci (QTLs) for FHB resistance were identified on chromosome arms
5AS and 5AL, with each explaining up to 20 and 32% of the variation in FHB severity, respectively. The two QTLs also showed
major effects on reducing the percentage of Fusarium damaged kernels (FDK) and deoxynivalenol (DON) accumulation in seeds.
FHB resistance has not previously been reported to be associated with this particular genomic region of chromosome arm 5AL,
thus indicating the novelty of FHB resistance in PI 277012. Plant maturity was not associated with FHB resistance and the
effects of plant height on FHB resistance were minor. Therefore, these results suggest that PI 277012 is an excellent source
for improving FHB resistance in wheat. The markers identified in this research are being used for marker-assisted introgression
of the QTLs into adapted durum and hard red spring wheat cultivars. 相似文献
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199.
A comprehensive physical contig of yeast artificial chromosomes (YACs) and cosmid clones between ZNF21 and DXS255 has been constructed, spanning 2 Mb within the region Xp11.23–p11.22. As a portion of the region was found to be particularly unstable in yeast, the integrity of the contig is dependent on additional information provided by the sequence-tagged site (STS) content of cosmid clones and DNA marker retention in conventional and radiation hybrids. The contig was formatted with 43 DNA markers, including 19 new STSs from YAC insert ends and an internalAlu-PCR product. The density of STSs across the contig ranges from one marker every 20 kb to one every 60 kb, with an average density of one marker every 50 kb. The relative order of previously known genes and expressed sequence tags in this region is predicted to be Xpter–ZNF21–DXS7465E (MG66)–DXS7927E (MG81)–WASP, DXS1011E, DXS7467E (MG21)–DXS- 7466E (MG44)–GATA1–DXS7469E (Xp664)–TFE3–SYP (DXS1007E)–Xcen. This contig extends the coverage in Xp11 and provides a framework for the future identification and mapping of new genes, as well as the resources for developing DNA sequencing templates. 相似文献
200.