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61.
Mitton-Fry RM Anderson EM Hughes TR Lundblad V Wuttke DS 《Science (New York, N.Y.)》2002,296(5565):145-147
The essential Cdc13 protein in the yeast Saccharomyces cerevisiae is a single-stranded telomeric DNA binding protein required for chromosome end protection and telomere replication. Here we report the solution structure of the Cdc13 DNA binding domain in complex with telomeric DNA. The structure reveals the use of a single OB (oligonucleotide/oligosaccharide binding) fold augmented by an unusually large loop for DNA recognition. This OB fold is structurally similar to OB folds found in the ciliated protozoan telomere end-binding protein, although no sequence similarity is apparent between them. The common usage of an OB fold for telomeric DNA interaction demonstrates conservation of end-protection mechanisms among eukaryotes. 相似文献
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Krause O Rieke GH Birkmann SM Le Floc'h E Gordon KD Egami E Bieging J Hughes JP Young ET Hinz JL Quanz SP Hines DC 《Science (New York, N.Y.)》2005,308(5728):1604-1606
Two images of Cassiopeia A obtained at 24 micrometers with the Spitzer Space Telescope over a 1-year time interval show moving structures outside the shell of the supernova remnant to a distance of more than 20 arc minutes. Individual features exhibit apparent motions of 10 to 20 arc seconds per year, independently confirmed by near-infrared observations. The observed tangential velocities are at roughly the speed of light. It is likely that the moving structures are infrared echoes, in which interstellar dust is heated by the explosion and by flares from the compact object near the center of the remnant. 相似文献
64.
The evolution of worker behavior in the social insects is usually explained by kin selection: although workers do not produce offspring, they do reproduce their genes by aiding the reproduction of relatives. The most difficult case for kin selection theory would be species in which workers are fully capable of reproducing but instead opt to rear brood of low relatedness. These conditions are perhaps best fulfilled by the swarm-founding wasps because they have little caste differentiation and their colonies usually have multiple queens, which should lower relatedness. Estimates of within-colony relatedness for three species in this group confirm that it is sometimes (but not always) very low. Inbreeding is negligible in these species, so the hypothesis that inbreeding may raise relatedness is not supported. The maintenance of worker behavior in such species is a significant challenge for kin selection theory. 相似文献
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Hughes CE 《Science (New York, N.Y.)》1925,61(1567):24-26
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