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排序方式: 共有793条查询结果,搜索用时 31 毫秒
91.
Pascal AA Liu Z Broess K van Oort B van Amerongen H Wang C Horton P Robert B Chang W Ruban A 《Nature》2005,436(7047):134-137
In order to maximize their use of light energy in photosynthesis, plants have molecules that act as light-harvesting antennae, which collect light quanta and deliver them to the reaction centres, where energy conversion into a chemical form takes place. The functioning of the antenna responds to the extreme changes in the intensity of sunlight encountered in nature. In shade, light is efficiently harvested in photosynthesis. However, in full sunlight, much of the energy absorbed is not needed and there are vitally important switches to specific antenna states, which safely dissipate the excess energy as heat. This is essential for plant survival, because it provides protection against the potential photo-damage of the photosynthetic membrane. But whereas the features that establish high photosynthetic efficiency have been highlighted, almost nothing is known about the molecular nature of the dissipative states. Recently, the atomic structure of the major plant light-harvesting antenna protein, LHCII, has been determined by X-ray crystallography. Here we demonstrate that this is the structure of a dissipative state of LHCII. We present a spectroscopic analysis of this crystal form, and identify the specific changes in configuration of its pigment population that give LHCII the intrinsic capability to regulate energy flow. This provides a molecular basis for understanding the control of photosynthetic light-harvesting. 相似文献
92.
93.
Batourina E Tsai S Lambert S Sprenkle P Viana R Dutta S Hensle T Wang F Niederreither K McMahon AP Carroll TJ Mendelsohn CL 《Nature genetics》2005,37(10):1082-1089
Removal of toxic substances from the blood depends on patent connections between the kidney, ureters and bladder that are established when the ureter is transposed from its original insertion site in the male genital tract to the bladder. This transposition is thought to occur as the trigone forms from the common nephric duct and incorporates into the bladder. Here we re-examine this model in the context of normal and abnormal development. We show that the common nephric duct does not differentiate into the trigone but instead undergoes apoptosis, a crucial step for ureter transposition controlled by vitamin A-induced signals from the primitive bladder. Ureter abnormalities occur in 1-2% of the human population and can cause obstruction and end-stage renal disease. These studies provide an explanation for ureter defects underlying some forms of obstruction in humans and redefine the current model of ureter maturation. 相似文献
94.
Ross AJ May-Simera H Eichers ER Kai M Hill J Jagger DJ Leitch CC Chapple JP Munro PM Fisher S Tan PL Phillips HM Leroux MR Henderson DJ Murdoch JN Copp AJ Eliot MM Lupski JR Kemp DT Dollfus H Tada M Katsanis N Forge A Beales PL 《Nature genetics》2005,37(10):1135-1140
The evolutionarily conserved planar cell polarity (PCP) pathway (or noncanonical Wnt pathway) drives several important cellular processes, including epithelial cell polarization, cell migration and mitotic spindle orientation. In vertebrates, PCP genes have a vital role in polarized convergent extension movements during gastrulation and neurulation. Here we show that mice with mutations in genes involved in Bardet-Biedl syndrome (BBS), a disorder associated with ciliary dysfunction, share phenotypes with PCP mutants including open eyelids, neural tube defects and disrupted cochlear stereociliary bundles. Furthermore, we identify genetic interactions between BBS genes and a PCP gene in both mouse (Ltap, also called Vangl2) and zebrafish (vangl2). In zebrafish, the augmented phenotype results from enhanced defective convergent extension movements. We also show that Vangl2 localizes to the basal body and axoneme of ciliated cells, a pattern reminiscent of that of the BBS proteins. These data suggest that cilia are intrinsically involved in PCP processes. 相似文献
95.
Zarnecki JC Leese MR Hathi B Ball AJ Hagermann A Towner MC Lorenz RD McDonnell JA Green SF Patel MR Ringrose TJ Rosenberg PD Atkinson KR Paton MD Banaszkiewicz M Clark BC Ferri F Fulchignoni M Ghafoor NA Kargl G Svedhem H Delderfield J Grande M Parker DJ Challenor PG Geake JE 《Nature》2005,438(7069):792-795
The surface of Saturn's largest satellite--Titan--is largely obscured by an optically thick atmospheric haze, and so its nature has been the subject of considerable speculation and discussion. The Huygens probe entered Titan's atmosphere on 14 January 2005 and descended to the surface using a parachute system. Here we report measurements made just above and on the surface of Titan by the Huygens Surface Science Package. Acoustic sounding over the last 90 m above the surface reveals a relatively smooth, but not completely flat, surface surrounding the landing site. Penetrometry and accelerometry measurements during the probe impact event reveal that the surface was neither hard (like solid ice) nor very compressible (like a blanket of fluffy aerosol); rather, the Huygens probe landed on a relatively soft solid surface whose properties are analogous to wet clay, lightly packed snow and wet or dry sand. The probe settled gradually by a few millimetres after landing. 相似文献
96.
Levskaya A Chevalier AA Tabor JJ Simpson ZB Lavery LA Levy M Davidson EA Scouras A Ellington AD Marcotte EM Voigt CA 《Nature》2005,438(7067):441-442
We have designed a bacterial system that is switched between different states by red light. The system consists of a synthetic sensor kinase that allows a lawn of bacteria to function as a biological film, such that the projection of a pattern of light on to the bacteria produces a high-definition (about 100 megapixels per square inch), two-dimensional chemical image. This spatial control of bacterial gene expression could be used to 'print' complex biological materials, for example, and to investigate signalling pathways through precise spatial and temporal control of their phosphorylation steps. 相似文献
97.
Lobov IB Rao S Carroll TJ Vallance JE Ito M Ondr JK Kurup S Glass DA Patel MS Shu W Morrisey EE McMahon AP Karsenty G Lang RA 《Nature》2005,437(7057):417-421
Macrophages have a critical role in inflammatory and immune responses through their ability to recognize and engulf apoptotic cells. Here we show that macrophages initiate a cell-death programme in target cells by activating the canonical WNT pathway. We show in mice that macrophage WNT7b is a short-range paracrine signal required for WNT-pathway responses and programmed cell death in the vascular endothelial cells of the temporary hyaloid vessels of the developing eye. These findings indicate that macrophages can use WNT ligands to influence cell-fate decisions--including cell death--in adjacent cells, and raise the possibility that they do so in many different cellular contexts. 相似文献
98.
Microarray analysis shows that some microRNAs downregulate large numbers of target mRNAs 总被引:11,自引:0,他引:11
Lim LP Lau NC Garrett-Engele P Grimson A Schelter JM Castle J Bartel DP Linsley PS Johnson JM 《Nature》2005,433(7027):769-773
99.
100.
J Sulston Z Du K Thomas R Wilson L Hillier R Staden N Halloran P Green J Thierry-Mieg L Qiu 《Nature》1992,356(6364):37-41
The long-term goal of this project is the elucidation of the complete sequence of the Caenorhabditis elegans genome. During the first year methods have been developed and a strategy implemented that is amenable to large-scale sequencing. The three cosmids sequenced in this initial phase are surprisingly rich in genes, many of which have mammalian homologues. 相似文献