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41.
Motor disorder in Huntington's disease begins as a dysfunction in error feedback control 总被引:14,自引:0,他引:14
A steady progression of motor dysfunction takes place in Huntington's disease (HD). The origin of this disturbance with relation to the motor control process is not understood. Here we studied reaching movements in asymptomatic HD gene-carriers (AGCs) and subjects with manifest HD. We found that movement jerkiness, which characterizes the smoothness and efficiency of motion, was a sensitive indicator of presymptomatic HD progression. A large fraction of AGCs displayed elevated jerk even when more than seven years remained until predicted disease onset. Movement termination was disturbed much more than initiation and was highly variable from trial to trial. Analysis of this variability revealed that the sensitivity of end-movement jerk to subtle, self-generated early-movement errors was greater in HD subjects than in controls. Additionally, we found that HD corrective responses to externally-generated force pulses were greatly disturbed, indicating that HD subjects display aberrant responses to both external and self-generated errors. Because feedback corrections are driven by error and are delayed such that they predominantly affect movement termination, these findings suggest that a dysfunction in error correction characterizes the motor control deficit in early HD. This dysfunction may be observed years before clinical disease onset and grows worse as the disease progresses. 相似文献
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During meiosis, cohesins--protein complexes that hold sister chromatids together--are lost from chromosomes in a step-wise manner. Loss of cohesins from chromosome arms is necessary for homologous chromosomes to segregate during meiosis I. Retention of cohesins around centromeres until meiosis II is required for the accurate segregation of sister chromatids. Here we show that phosphorylation of the cohesin subunit Rec8 contributes to step-wise cohesin removal. Our data further implicate two other key regulators of meiotic chromosome segregation, the cohesin protector Sgo1 and meiotic recombination in bringing about the step-wise loss of cohesins and thus the establishment of the meiotic chromosome segregation pattern. Understanding the interplay between these processes should provide insight into the events underlying meiotic chromosome mis-segregation, the leading cause of miscarriages and mental retardation in humans. 相似文献
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Deciphering the evolution and metabolism of an anammox bacterium from a community genome 总被引:15,自引:0,他引:15
Strous M Pelletier E Mangenot S Rattei T Lehner A Taylor MW Horn M Daims H Bartol-Mavel D Wincker P Barbe V Fonknechten N Vallenet D Segurens B Schenowitz-Truong C Médigue C Collingro A Snel B Dutilh BE Op den Camp HJ van der Drift C Cirpus I van de Pas-Schoonen KT Harhangi HR van Niftrik L Schmid M Keltjens J van de Vossenberg J Kartal B Meier H Frishman D Huynen MA Mewes HW Weissenbach J Jetten MS Wagner M Le Paslier D 《Nature》2006,440(7085):790-794
Anaerobic ammonium oxidation (anammox) has become a main focus in oceanography and wastewater treatment. It is also the nitrogen cycle's major remaining biochemical enigma. Among its features, the occurrence of hydrazine as a free intermediate of catabolism, the biosynthesis of ladderane lipids and the role of cytoplasm differentiation are unique in biology. Here we use environmental genomics--the reconstruction of genomic data directly from the environment--to assemble the genome of the uncultured anammox bacterium Kuenenia stuttgartiensis from a complex bioreactor community. The genome data illuminate the evolutionary history of the Planctomycetes and allow us to expose the genetic blueprint of the organism's special properties. Most significantly, we identified candidate genes responsible for ladderane biosynthesis and biological hydrazine metabolism, and discovered unexpected metabolic versatility. 相似文献
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Landscape of transcription in human cells 总被引:3,自引:0,他引:3
S Djebali CA Davis A Merkel A Dobin T Lassmann A Mortazavi A Tanzer J Lagarde W Lin F Schlesinger C Xue GK Marinov J Khatun BA Williams C Zaleski J Rozowsky M Röder F Kokocinski RF Abdelhamid T Alioto I Antoshechkin MT Baer NS Bar P Batut K Bell I Bell S Chakrabortty X Chen J Chrast J Curado T Derrien J Drenkow E Dumais J Dumais R Duttagupta E Falconnet M Fastuca K Fejes-Toth P Ferreira S Foissac MJ Fullwood H Gao D Gonzalez A Gordon H Gunawardena C Howald S Jha R Johnson P Kapranov B King 《Nature》2012,489(7414):101-108
Eukaryotic cells make many types of primary and processed RNAs that are found either in specific subcellular compartments or throughout the cells. A complete catalogue of these RNAs is not yet available and their characteristic subcellular localizations are also poorly understood. Because RNA represents the direct output of the genetic information encoded by genomes and a significant proportion of a cell's regulatory capabilities are focused on its synthesis, processing, transport, modification and translation, the generation of such a catalogue is crucial for understanding genome function. Here we report evidence that three-quarters of the human genome is capable of being transcribed, as well as observations about the range and levels of expression, localization, processing fates, regulatory regions and modifications of almost all currently annotated and thousands of previously unannotated RNAs. These observations, taken together, prompt a redefinition of the concept of a gene. 相似文献
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Functions and malfunctions of the tau proteins 总被引:9,自引:1,他引:8
The tau proteins belong to the family of microtubule-associated proteins. They are mainly expressed in neurons where they
play major regulatory roles in the organization and integrity of the cytoskeleton network. Neurofibrillary changes of abnormally
hyperphosphorylated tau are a key lesion in Alzheimer's disease and a number of other tauopathies. However, despite an ever-increasing
body of data on the changes which tau undergoes in disease, its role regarding the fundamental disease process is still unclear.
Moreover, conceptions of tau functions continue to evolve, which complicates an understanding of its role in the disease process.
This review attempts to summarize data on the role of tau proteins in the context of both normal cellular function and dysfunction.
Furthermore, we try to develop a mechanistic framework for the involvement of tau during the disease process. The review closes
with a look towards various approaches to elucidate the functions and malfunctions of tau.
Received 21 June 2002; received after revision 24 July 2002; accepted 29 July 2002
RID="*"
ID="*"Corresponding author. 相似文献
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I. Brandt A. Bergman C. A. Wachtmeister 《Cellular and molecular life sciences : CMLS》1976,32(4):497-498
Summary Autoradiography showed that labelled polychlorinated biphenyls with chlorine in positions 2, 41, 5 and hydrogen in positions 3, 31, 6, 61 in the molecule are accumulated in the mouse bronchial mucosa. Further testing of this observation showed that 2, 21, 4, 51-tetrachlorbiphenyl-14C, but not biphenyl-14C, was taken up in the bronchi of mice.This investigation was supported by the National Swedish Environment Protection Board. 相似文献
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Muscle contraction: the effect of ionic strength 总被引:15,自引:0,他引:15