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991.
Imprinted microRNA genes transcribed antisense to a reciprocally imprinted retrotransposon-like gene 总被引:18,自引:0,他引:18
Seitz H Youngson N Lin SP Dalbert S Paulsen M Bachellerie JP Ferguson-Smith AC Cavaillé J 《Nature genetics》2003,34(3):261-262
MicroRNAs (miRNAs) are an abundant class of RNAs that are approximately 21-25 nucleotides (nt) long, interact with mRNAs and trigger either translation repression or RNA cleavage (RNA interference, RNAi) depending on the degree of complementarity with their targets. Here we show that the imprinted mouse distal chromosome 12 locus encodes two miRNA genes expressed from the maternally inherited chromosome and antisense to a retrotransposon-like gene (Rtl1) expressed only from the paternal allele. 相似文献
992.
993.
Hypotrichosis simplex of the scalp is associated with nonsense mutations in CDSN encoding corneodesmosin 总被引:6,自引:0,他引:6
Levy-Nissenbaum E Betz RC Frydman M Simon M Lahat H Bakhan T Goldman B Bygum A Pierick M Hillmer AM Jonca N Toribio J Kruse R Dewald G Cichon S Kubisch C Guerrin M Serre G Nöthen MM Pras E 《Nature genetics》2003,34(2):151-153
We have identified nonsense mutations in the gene CDSN (encoding corneodesmosin) in three families suffering from hypotrichosis simplex of the scalp (HSS; OMIM 146520). CDSN, a glycoprotein expressed in the epidermis and inner root sheath (IRS) of hair follicles, is a keratinocyte adhesion molecule. Truncated CDSN aggregates were detected in the superficial dermis and at the periphery of hair follicles. Our findings suggest that CDSN is important in normal scalp hair physiology. 相似文献
994.
Genomic islands, such as pathogenicity islands, contribute to the evolution and diversification of microbial life. Here we report on the Widespread Colonization Island, which encompasses the tad (tight adherence) locus for colonization of surfaces and biofilm formation by the human pathogen Actinobacillus actinomycetemcomitans. At least 12 of the 14 genes at the tad locus are required for tenacious biofilm formation and synthesis of bundled Flp pili (fibrils) that mediate adherence. The pilin subunit, Flp1, remains inside the cell in tad-locus mutants, indicating that these genes encode a secretion system for export and assembly of fibrils. We found tad-related regions in a wide variety of Bacterial and Archaeal species, and their sequence characteristics indicate possible horizontal transfer. To test the hypothesis of horizontal transfer, we compared the phylogeny of the tad locus to a robust organismal phylogeny using statistical tests of congruence and tree reconciliation techniques. Our analysis strongly supports a complex history of gene shuffling by recombination and multiple horizontal transfers, duplications and losses. We present evidence for a specific horizontal transfer event leading to the establishment of this region as a determinant of disease. 相似文献
995.
Inada N Oguri M Pindor B Hennawi JF Chiu K Zheng W Ichikawa S Gregg MD Becker RH Suto Y Strauss MA Turner EL Keeton CR Annis J Castander FJ Eisenstein DJ Frieman JA Fukugita M Gunn JE Johnston DE Kent SM Nichol RC Richards GT Rix HW Sheldon ES Bahcall NA Brinkmann J Ivezić Z Lamb DQ McKay TA Schneider DP York DG 《Nature》2003,426(6968):810-812
Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures (that is, clusters of galaxies and even larger assemblies) predicts the existence of quasars gravitationally lensed by concentrations of dark matter so massive that the quasar images would be split by over 7 arcsec. Numerous searches for large-separation lensed quasars have, however, been unsuccessful. All of the roughly 70 lensed quasars known, including the first lensed quasar discovered, have smaller separations that can be explained in terms of galaxy-scale concentrations of baryonic matter. Although gravitationally lensed galaxies with large separations are known, quasars are more useful cosmological probes because of the simplicity of the resulting lens systems. Here we report the discovery of a lensed quasar, SDSS J1004 + 4112, which has a maximum separation between the components of 14.62 arcsec. Such a large separation means that the lensing object must be dominated by dark matter. Our results are fully consistent with theoretical expectations based on the cold-dark-matter model. 相似文献
996.
Burgay M D'Amico N Possenti A Manchester RN Lyne AG Joshi BC McLaughlin MA Kramer M Sarkissian JM Camilo F Kalogera V Kim C Lorimer DR 《Nature》2003,426(6966):531-533
The merger of close binary systems containing two neutron stars should produce a burst of gravitational waves, as predicted by the theory of general relativity. A reliable estimate of the double-neutron-star merger rate in the Galaxy is crucial in order to predict whether current gravity wave detectors will be successful in detecting such bursts. Present estimates of this rate are rather low, because we know of only a few double-neutron-star binaries with merger times less than the age of the Universe. Here we report the discovery of a 22-ms pulsar, PSR J0737-3039, which is a member of a highly relativistic double-neutron-star binary with an orbital period of 2.4 hours. This system will merge in about 85 Myr, a time much shorter than for any other known neutron-star binary. Together with the relatively low radio luminosity of PSR J0737-3039, this timescale implies an order-of-magnitude increase in the predicted merger rate for double-neutron-star systems in our Galaxy (and in the rest of the Universe). 相似文献
997.
Price PA Fox DW Kulkarni SR Peterson BA Schmidt BP Soderberg AM Yost SA Berger E Djorgovski SG Frail DA Harrison FA Sari R Blain AW Chapman SC 《Nature》2003,423(6942):844-847
Past studies of cosmological gamma-ray bursts (GRBs) have been hampered by their extreme distances, resulting in faint afterglows. A nearby GRB could potentially shed much light on the origin of these events, but GRBs with a redshift z 相似文献
998.
The phytochromes are a family of plant photoreceptor proteins that control several adaptive developmental strategies. For example, the phytochromes perceive far-red light (wavelengths between 700 and 800 nm) reflected or scattered from the leaves of nearby vegetation. This provides an early warning of potential shading, and triggers a series of 'shade-avoidance' responses, such as a rapid increase in elongation, by which the plant attempts to overgrow its neighbours. Other, less immediate, responses include accelerated flowering and early production of seeds. However, little is known about the molecular events that connect light perception with increased growth in shade avoidance. Here we show that the circadian clock gates this rapid shade-avoidance response. It is most apparent around dusk and is accompanied by altered expression of several genes. One of these rapidly responsive genes encodes a basic helix-loop-helix protein, PIL1, previously shown to interact with the clock protein TOC1 (ref. 4). Furthermore PIL1 and TOC1 are both required for the accelerated growth associated with the shade-avoidance response. 相似文献
999.
Little is known about the origins of globular clusters, which contain hundreds of thousands of stars in a volume only a few light years across. Radiation pressure and winds from luminous young stars should disperse the star-forming gas and disrupt the formation of the cluster. Globular clusters in our Galaxy cannot provide answers; they are billions of years old. Here we report the measurement of infrared hydrogen recombination lines from a young, forming super star cluster in the dwarf galaxy NGC5253. The lines arise in gas heated by a cluster of about one million stars, including 4,000-6,000 massive, hot 'O' stars. It is so young that it is still enshrouded in gas and dust, hidden from optical view. The gases within the cluster seem bound by gravity, which may explain why the windy and luminous O stars have not yet blown away those gases. Young clusters in 'starbursting' galaxies in the local and distant Universe may also be gravitationally confined and cloaked from view. 相似文献
1000.
REE geochemistry of suspended sediments from the rivers around the Yellow Sea and provenance indicators 总被引:11,自引:0,他引:11
YANGShouye LICongxian C.B.Lee T.K.Na 《科学通报(英文版)》2003,48(11):1135-1139
Rare earth element (REE) compositions of the suspended sediments from the rivers around the Yellow Sea were different in that Korean river sediments (Han, Keum and Yeongsan Rivers) yield stronger fractionations than Chinese river sediments (Changjiang, Huanghe and Yalujiang), shown by obvious enrichments of LREE (light rare earth element) relative to UCC (upper continental crust).Variations of source rock compositions in the drainage basins are responsible for the differences of REE compositions between the river sediments. REE fractionation parameters including (La/Yb)ucc and (Gd/Yb)ucc as well as the ratios of La/Sc and Th/Sc can be treated as proper proxies for identifying the Chinese river sediments from those Korean river matters, and furthermore, for studying the provenances and paleoenvironmental changes of the marginal seas of China. 相似文献