排序方式: 共有41条查询结果,搜索用时 15 毫秒
31.
Haemoglobin Constant Spring--a chain termination mutant? 总被引:32,自引:0,他引:32
32.
Interleukin 21 and its receptor are involved in NK cell expansion and regulation of lymphocyte function 总被引:64,自引:0,他引:64
Parrish-Novak J Dillon SR Nelson A Hammond A Sprecher C Gross JA Johnston J Madden K Xu W West J Schrader S Burkhead S Heipel M Brandt C Kuijper JL Kramer J Conklin D Presnell SR Berry J Shiota F Bort S Hambly K Mudri S Clegg C Moore M Grant FJ Lofton-Day C Gilbert T Rayond F Ching A Yao L Smith D Webster P Whitmore T Maurer M Kaushansky K Holly RD Foster D 《Nature》2000,408(6808):57-63
Cytokines are important in the regulation of haematopoiesis and immune responses, and can influence lymphocyte development. Here we have identified a class I cytokine receptor that is selectively expressed in lymphoid tissues and is capable of signal transduction. The full-length receptor was expressed in BaF3 cells, which created a functional assay for ligand detection and cloning. Conditioned media from activated human CD3+ T cells supported proliferation of the assay cell line. We constructed a complementary DNA expression library from activated human CD3+ T cells, and identified a cytokine with a four-helix-bundle structure using functional cloning. This cytokine is most closely related to IL2 and IL15, and has been designated IL21 with the receptor designated IL21 R. In vitro assays suggest that IL21 has a role in the proliferation and maturation of natural killer (NK) cell populations from bone marrow, in the proliferation of mature B-cell populations co-stimulated with anti-CD40, and in the proliferation of T cells co-stimulated with anti-CD3. 相似文献
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34.
S Ottolenghi W G Lanyon J Paul R Williamson D J Weatherall J B Clegg J Pritchard S Pootrakul W H Boon 《Nature》1974,251(5474):389-392
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36.
Chloroplast DNA sequence from a miocene Magnolia species 总被引:18,自引:0,他引:18
E M Golenberg D E Giannasi M T Clegg C J Smiley M Durbin D Henderson G Zurawski 《Nature》1990,344(6267):656-658
DNA has been successfully extracted from several samples of preserved tissue, the oldest so far reported originating from a 13,000-year-old ground sloth. Both severe damage to the preserved DNA, primarily due to oxidation of the pyrimidines, has prevented the acquisition of sequence data from ancient samples except in a few cases. We report here the extraction of DNA from fossil leaf samples from the Miocene Clarkia deposit (17-20 Myr old), the amplification of an 820-base pair (bp) DNA fragment from the chloroplast gene rbcL from a fossil of the genus Magnolia, and its subsequent sequencing. The sequence was verified by comparison with published and unpublished rbcL sequences. These results extend our ability to analyse ancient DNA and may open new avenues into problems in palaeobotany, biogeography, and in the calibration of mutation rates. 相似文献
37.
Fluorescence energy transfer shows that the four-way DNA junction is a right-handed cross of antiparallel molecules 总被引:30,自引:0,他引:30
A I Murchie R M Clegg E von Kitzing D R Duckett S Diekmann D M Lilley 《Nature》1989,341(6244):763-766
The four-way junction between DNA helices is the central intermediate in recombination, and the manner of its interaction with resolvase enzymes can determine the genetic outcome of the process. A knowledge of its structure is a prerequisite to understanding the interaction with proteins, and there has been recent progress. Here we use fluorescence energy transfer to determine the relative distances between the ends of a small DNA junction, and hence the path of the strands. Our results are consistent with the geometry of an 'X'. The interconnected helices are juxtaposed so that the continuous strands of each helix generate an antiparallel alignment, and the two interchanged strands do not cross at the centre. The acute angle of the X structure is defined by a right-handed rotation of the helical axes about the axis perpendicular to the X plane, as viewed from the centre of the X. 相似文献
38.
Humphray SJ Oliver K Hunt AR Plumb RW Loveland JE Howe KL Andrews TD Searle S Hunt SE Scott CE Jones MC Ainscough R Almeida JP Ambrose KD Ashwell RI Babbage AK Babbage S Bagguley CL Bailey J Banerjee R Barker DJ Barlow KF Bates K Beasley H Beasley O Bird CP Bray-Allen S Brown AJ Brown JY Burford D Burrill W Burton J Carder C Carter NP Chapman JC Chen Y Clarke G Clark SY Clee CM Clegg S Collier RE Corby N Crosier M Cummings AT Davies J Dhami P Dunn M Dutta I Dyer LW Earthrowl ME Faulkner L 《Nature》2004,429(6990):369-374
Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection. 相似文献
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J B Clegg D J Weatherall I Contopolou-Griva K Caroutsos P Poungouras H Tsevrenis 《Nature》1974,251(5472):245-247
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Alpha-thalassaemia caused by a polyadenylation signal mutation 总被引:3,自引:0,他引:3
D R Higgs S E Goodbourn J Lamb J B Clegg D J Weatherall N J Proudfoot 《Nature》1983,306(5941):398-400