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191.
Wen JD Lancaster L Hodges C Zeri AC Yoshimura SH Noller HF Bustamante C Tinoco I 《Nature》2008,452(7187):598-603
We have followed individual ribosomes as they translate single messenger RNA hairpins tethered by the ends to optical tweezers. Here we reveal that translation occurs through successive translocation--and-pause cycles. The distribution of pause lengths, with a median of 2.8 s, indicates that at least two rate-determining processes control each pause. Each translocation step measures three bases--one codon-and occurs in less than 0.1 s. Analysis of the times required for translocation reveals, surprisingly, that there are three substeps in each step. Pause lengths, and thus the overall rate of translation, depend on the secondary structure of the mRNA; the applied force destabilizes secondary structure and decreases pause durations, but does not affect translocation times. Translocation and RNA unwinding are strictly coupled ribosomal functions. 相似文献
192.
193.
Warren WC Hillier LW Marshall Graves JA Birney E Ponting CP Grützner F Belov K Miller W Clarke L Chinwalla AT Yang SP Heger A Locke DP Miethke P Waters PD Veyrunes F Fulton L Fulton B Graves T Wallis J Puente XS López-Otín C Ordóñez GR Eichler EE Chen L Cheng Z Deakin JE Alsop A Thompson K Kirby P Papenfuss AT Wakefield MJ Olender T Lancet D Huttley GA Smit AF Pask A Temple-Smith P Batzer MA Walker JA Konkel MK Harris RS Whittington CM Wong ES Gemmell NJ Buschiazzo E Vargas Jentzsch IM Merkel A 《Nature》2008,453(7192):175-183
We present a draft genome sequence of the platypus, Ornithorhynchus anatinus. This monotreme exhibits a fascinating combination of reptilian and mammalian characters. For example, platypuses have a coat of fur adapted to an aquatic lifestyle; platypus females lactate, yet lay eggs; and males are equipped with venom similar to that of reptiles. Analysis of the first monotreme genome aligned these features with genetic innovations. We find that reptile and platypus venom proteins have been co-opted independently from the same gene families; milk protein genes are conserved despite platypuses laying eggs; and immune gene family expansions are directly related to platypus biology. Expansions of protein, non-protein-coding RNA and microRNA families, as well as repeat elements, are identified. Sequencing of this genome now provides a valuable resource for deep mammalian comparative analyses, as well as for monotreme biology and conservation. 相似文献
194.
Gómez-Consarnau L González JM Coll-Lladó M Gourdon P Pascher T Neutze R Pedrós-Alió C Pinhassi J 《Nature》2007,445(7124):210-213
Proteorhodopsins are bacterial light-dependent proton pumps. Their discovery within genomic material from uncultivated marine bacterioplankton caused considerable excitement because it indicated a potential phototrophic function within these organisms, which had previously been considered strictly chemotrophic. Subsequent studies established that sequences encoding proteorhodopsin are broadly distributed throughout the world's oceans. Nevertheless, the role of proteorhodopsins in native marine bacteria is still unknown. Here we show, from an analysis of the complete genomes of three marine Flavobacteria, that cultivated bacteria in the phylum Bacteroidetes, one of the principal components of marine bacterioplankton, contain proteorhodopsin. Moreover, growth experiments in both natural and artificial seawater (low in labile organic matter, which is typical of the world's oceans) establish that exposure to light results in a marked increase in the cell yield of one such bacterium (Dokdonia sp. strain MED134) when compared with cells grown in darkness. Thus, our results show that the phototrophy conferred by proteorhodopsin can provide critical amounts of energy, not only for respiration and maintenance but also for active growth of marine bacterioplankton in their natural environment. 相似文献
195.
淡水豚类mtDNA 16S rRNA基因的系统发生 总被引:8,自引:0,他引:8
mtDNA 16S rRNA基因我分析支持将现生淡水豚4个属归入不同的科,即白暨豚科(Lipotiidae)、恒河豚科(Platanistidae)、亚河豚科(Iniidae)和弗西豚科(Pontoporidae)。基于邻接法的系统发生分析显示淡水豚类由白暨豚+恒河豚和弗西豚+亚河豚两个单系组成,但两个单系之间并无姊妹关系。淡水豚类是并系的。16S rRNA基因的系统发生树与mtDNA细胞色素b基 相似文献
196.
The genome of Theobroma cacao 总被引:2,自引:0,他引:2
Argout X Salse J Aury JM Guiltinan MJ Droc G Gouzy J Allegre M Chaparro C Legavre T Maximova SN Abrouk M Murat F Fouet O Poulain J Ruiz M Roguet Y Rodier-Goud M Barbosa-Neto JF Sabot F Kudrna D Ammiraju JS Schuster SC Carlson JE Sallet E Schiex T Dievart A Kramer M Gelley L Shi Z Bérard A Viot C Boccara M Risterucci AM Guignon V Sabau X Axtell MJ Ma Z Zhang Y Brown S Bourge M Golser W Song X Clement D Rivallan R Tahi M Akaza JM Pitollat B Gramacho K D'Hont A Brunel D Infante D Kebe I Costet P 《Nature genetics》2011,43(2):101-108
We sequenced and assembled the draft genome of Theobroma cacao, an economically important tropical-fruit tree crop that is the source of chocolate. This assembly corresponds to 76% of the estimated genome size and contains almost all previously described genes, with 82% of these genes anchored on the 10 T. cacao chromosomes. Analysis of this sequence information highlighted specific expansion of some gene families during evolution, for example, flavonoid-related genes. It also provides a major source of candidate genes for T. cacao improvement. Based on the inferred paleohistory of the T. cacao genome, we propose an evolutionary scenario whereby the ten T. cacao chromosomes were shaped from an ancestor through eleven chromosome fusions. 相似文献
197.
The central nervous system (CNS) is considered an immune-privileged organ that maintains an adaptable immune surveillance
system. Dysregulated immune function within the CNS contributes to the development of brain tumor growth, and robust immune
activation results in excessive inflammation. Human lymphocyte antigen-G (HLA-G) proteins with tolerogenic immunoreactivity
have been implicated in various pathophysiological processes including immune surveillance, governing homeostasis and immune
regulation. In this review, we describe the wealth of evidence for the involvement of HLA-G in the CNS under physiological
and pathological conditions. Further, we review regulatory functions that may be applicable as beneficial strategies in the
therapeutic manipulation of immune-mediated CNS immune responses. Additionally, we try to understand how this molecule cooperates
with other CNS-resident cells to maintain normal immune homeostasis, while still facilitating the development of the appropriate
immune responses. 相似文献
198.
Laura Pellegrini Andrea Wetzel Simone Grannó George Heaton Kirsten Harvey 《Cellular and molecular life sciences : CMLS》2017,74(3):409-434
Cytoskeletal homeostasis is essential for the development, survival and maintenance of an efficient nervous system. Microtubules are highly dynamic polymers important for neuronal growth, morphology, migration and polarity. In cooperation with several classes of binding proteins, microtubules regulate long-distance intracellular cargo trafficking along axons and dendrites. The importance of a delicate interplay between cytoskeletal components is reflected in several human neurodegenerative disorders linked to abnormal microtubule dynamics, including Parkinson’s disease (PD). Mounting evidence now suggests PD pathogenesis might be underlined by early cytoskeletal dysfunction. Advances in genetics have identified PD-associated mutations and variants in genes encoding various proteins affecting microtubule function including the microtubule-associated protein tau. In this review, we highlight the role of microtubules, their major posttranslational modifications and microtubule associated proteins in neuronal function. We then present key evidence on the contribution of microtubule dysfunction to PD. Finally, we discuss how regulation of microtubule dynamics with microtubule-targeting agents and deacetylase inhibitors represents a promising strategy for innovative therapeutic development. 相似文献
199.
Transgenic expression and activation of PGC-1α protect dopaminergic neurons in the MPTP mouse model of Parkinson’s disease 总被引:1,自引:1,他引:0
200.
Ikram MA Fornage M Smith AV Seshadri S Schmidt R Debette S Vrooman HA Sigurdsson S Ropele S Taal HR Mook-Kanamori DO Coker LH Longstreth WT Niessen WJ DeStefano AL Beiser A Zijdenbos AP Struchalin M Jack CR Rivadeneira F Uitterlinden AG Knopman DS Hartikainen AL Pennell CE Thiering E Steegers EA Hakonarson H Heinrich J Palmer LJ Jarvelin MR McCarthy MI Grant SF St Pourcain B Timpson NJ Smith GD Sovio U;Early Growth Genetics Consortium Nalls MA Au R Hofman A Gudnason H van der Lugt A Harris TB 《Nature genetics》2012,44(5):539-544
During aging, intracranial volume remains unchanged and represents maximally attained brain size, while various interacting biological phenomena lead to brain volume loss. Consequently, intracranial volume and brain volume in late life reflect different genetic influences. Our genome-wide association study (GWAS) in 8,175 community-dwelling elderly persons did not reveal any associations at genome-wide significance (P < 5 × 10(-8)) for brain volume. In contrast, intracranial volume was significantly associated with two loci: rs4273712 (P = 3.4 × 10(-11)), a known height-associated locus on chromosome 6q22, and rs9915547 (P = 1.5 × 10(-12)), localized to the inversion on chromosome 17q21. We replicated the associations of these loci with intracranial volume in a separate sample of 1,752 elderly persons (P = 1.1 × 10(-3) for 6q22 and 1.2 × 10(-3) for 17q21). Furthermore, we also found suggestive associations of the 17q21 locus with head circumference in 10,768 children (mean age of 14.5 months). Our data identify two loci associated with head size, with the inversion at 17q21 also likely to be involved in attaining maximal brain size. 相似文献