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The discovery of the basis of genetic variation has opened inroads to understanding our history as a species. It has revealed the remarkable genetic similarity we share with other individuals as well as with our closest primate relatives. To understand what make us unique, both as individuals and as a species, we need to consider the genome as a mosaic of discrete segments, each with its own unique history and relatedness to different contemporary and ancestral individuals. 相似文献
995.
Human mitochondrial tRNAs in health and disease 总被引:6,自引:0,他引:6
Florentz C Sohm B Tryoen-Tóth P Pütz J Sissler M 《Cellular and molecular life sciences : CMLS》2003,60(7):1356-1375
The human mitochondrial genome encodes 13 proteins, all subunits of the respiratory chain
complexes and thus involved in energy metabolism. These genes are translated by 22 transfer RNAs
(tRNAs), also encoded by the mitochondrial genome, which form the minimal set required for reading
all codons. Human mitochondrial tRNAs gained interest with the rapid discovery of correlations
between point mutations in their genes and various neuromuscular and neurodegenerative disorders.
In this review, emerging fundamental knowledge on the structure/function relationships of these
particular tRNAs and an overview of the large variety of mechanisms within translation, affected by
mutations, are summarized. Also, initial results on wide-ranging molecular consequences of mutations
outside the frame of mitochondrial translation are highlighted. While knowledge of mitochondrial
tRNAs in both health and disease increases, deciphering the intricate network of events leading
different genotypes to the variety of phenotypes requires further investigation using adapted
model systems.Received 3 December 2002; received after revision 14 January 2003; accepted 27 January 2003 相似文献
996.
Kamath RS Fraser AG Dong Y Poulin G Durbin R Gotta M Kanapin A Le Bot N Moreno S Sohrmann M Welchman DP Zipperlen P Ahringer J 《Nature》2003,421(6920):231-237
997.
998.
An ICE pattern crystallizes 总被引:3,自引:0,他引:3
999.
Paul A Bartels RA Tobey R Green H Weiman S Christov IP Murnane MM Kapteyn HC Backus S 《Nature》2003,421(6918):51-54
High-harmonic generation is a well-known method of producing coherent extreme-ultraviolet (EUV) light, with photon energies up to about 0.5 keV (refs 1, 2). This is achieved by focusing a femtosecond laser into a gas, and high harmonics of the fundamental laser frequency are radiated in the forward direction. However, although this process can generate high-energy photons, efficient high-harmonic generation has been demonstrated only for photon energies of the order 50-100 eV (ref. 5). Ionization of the gas prevents the laser and the EUV light from propagating at the same speed, which severely limits the conversion efficiency. Here we report a technique to overcome this problem, and demonstrate quasi-phase-matched frequency conversion of laser light into EUV. Using a modulated hollow-core waveguide to periodically vary the intensity of the laser light driving the conversion, we efficiently generate EUV light even in the presence of substantial ionization. The use of a modulated fibre shifts the energy spectrum of the high-harmonic light to significantly higher photon energies than would otherwise be possible. We expect that this technique could form the basis of coherent EUV sources for advanced lithography and high-resolution imaging applications. In future work, it might also be possible to generate isolated attosecond pulses. 相似文献
1000.
Singh N Ebrahimi FA Gimelbrant AA Ensminger AW Tackett MR Qi P Gribnau J Chess A 《Nature genetics》2003,33(3):339-341
Random monoallelic expression and asynchronous replication define an unusual class of autosomal mammalian genes. We show that every cell has randomly chosen either the maternal or paternal copy of each given autosome pair, such that alleles of these genes scattered across the chosen chromosome replicate earlier than the alleles on the homologous chromosome. Thus, chromosome-pair non-equivalence, rather than being limited to X-chromosome inactivation, is a fundamental property of mouse chromosomes. 相似文献